Merge branch 'i2c/for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:

 - API for late atomic transfers (e.g. to shut down via PMIC). We have a
   seperate callback now which is called under clearly defined
   conditions. In-kernel users are converted, too.

 - new driver for the AMD PCIe MP2 I2C controller

 - large refactoring for at91 and bcm-iproc (both gain slave support due
   to this)

 - and a good share of various driver improvements anf fixes

* 'i2c/for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (57 commits)
  dt-bindings: i2c: riic: document r7s9210 support
  i2c: imx-lpi2c: Use __maybe_unused instead of #if CONFIG_PM_SLEEP
  i2c-piix4: Add Hygon Dhyana SMBus support
  i2c: core: apply 'is_suspended' check for SMBus, too
  i2c: core: ratelimit 'transfer when suspended' errors
  i2c: iproc: Change driver to use 'BIT' macro
  i2c: riic: Add Runtime PM support
  i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc()
  i2c: mux: pca954x: allow management of device idle state via sysfs
  i2c: mux: pca9541: remove support for unused platform data
  i2c: mux: pca954x: remove support for unused platform data
  dt-bindings: i2c: i2c-mtk: add support for MT8516
  i2c: axxia: use auto cmd for last message
  i2c: gpio: flag atomic capability if possible
  i2c: algo: bit: add flag to whitelist atomic transfers
  i2c: stu300: use xfer_atomic callback to bail out early
  i2c: ocores: enable atomic xfers
  i2c: ocores: refactor setup for polling
  i2c: tegra-bpmp: convert to use new atomic callbacks
  i2c: omap: Add the master_xfer_atomic hook
  ...

Documentation/ABI/testing/sysfs-bus-i2c-devices-pca954x

+What:		/sys/bus/i2c/.../idle_state
+Date:		January 2019
+KernelVersion:	5.2
+Contact:	Robert Shearman <robert.shearman@att.com>
+Description:
+		Value that exists only for mux devices that can be
+		written to control the behaviour of the multiplexer on
+		idle. Possible values:
+		-2 - disconnect on idle, i.e. deselect the last used
+		     channel, which is useful when there is a device
+		     with an address that conflicts with another
+		     device on another mux on the same parent bus.
+		-1 - leave the mux as-is, which is the most optimal
+		     setting in terms of I2C operations and is the
+		     default mode.
+		0..<nchans> - set the mux to a predetermined channel,
+		     which is useful if there is one channel that is
+		     used almost always, and you want to reduce the
+		     latency for normal operations after rare
+		     transactions on other channels

Documentation/devicetree/bindings/eeprom/at24.txt

@@ -50,6 +50,7 @@ Required properties:
 
                 "nxp,se97b" - the fallback is "atmel,24c02",
                 "renesas,r1ex24002" - the fallback is "atmel,24c02"
+                "renesas,r1ex24016" - the fallback is "atmel,24c16"
                 "renesas,r1ex24128" - the fallback is "atmel,24c128"
                 "rohm,br24t01" - the fallback is "atmel,24c01"
 

Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt

@@ -3,15 +3,12 @@ Broadcom iProc I2C controller
 Required properties:
 
 - compatible:
-    Must be "brcm,iproc-i2c"
+    Must be "brcm,iproc-i2c" or "brcm,iproc-nic-i2c"
 
 - reg:
     Define the base and range of the I/O address space that contain the iProc
     I2C controller registers
 
-- interrupts:
-    Should contain the I2C interrupt
-
 - clock-frequency:
     This is the I2C bus clock. Need to be either 100000 or 400000
 
@@ -21,6 +18,18 @@ Required properties:
 - #size-cells:
     Always 0
 
+Optional properties:
+
+- interrupts:
+    Should contain the I2C interrupt. For certain revisions of the I2C
+    controller, I2C interrupt is unwired to the interrupt controller. In such
+    case, this property should be left unspecified, and driver will fall back
+    to polling mode
+
+- brcm,ape-hsls-addr-mask:
+    Required for "brcm,iproc-nic-i2c". Host view of address mask into the
+    'APE' co-processor. Value must be unsigned, 32-bit
+
 Example:
 	i2c0: i2c@18008000 {
 		compatible = "brcm,iproc-i2c";

Documentation/devicetree/bindings/i2c/i2c-designware.txt

@@ -6,12 +6,21 @@ Required properties :
                 or "mscc,ocelot-i2c" with "snps,designware-i2c" for fallback
  - reg : Offset and length of the register set for the device
  - interrupts : <IRQ> where IRQ is the interrupt number.
+ - clocks : phandles for the clocks, see the description of clock-names below.
+   The phandle for the "ic_clk" clock is required. The phandle for the "pclk"
+   clock is optional. If a single clock is specified but no clock-name, it is
+   the "ic_clk" clock. If both clocks are listed, the "ic_clk" must be first.
 
 Recommended properties :
 
  - clock-frequency : desired I2C bus clock frequency in Hz.
 
 Optional properties :
+
+ - clock-names : Contains the names of the clocks:
+    "ic_clk", for the core clock used to generate the external I2C clock.
+    "pclk", the interface clock, required for register access.
+
  - reg : for "mscc,ocelot-i2c", a second register set to configure the SDA hold
    time, named ICPU_CFG:TWI_DELAY in the datasheet.
 

Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt

@@ -12,13 +12,16 @@ Required properties:
       "mediatek,mt7623-i2c", "mediatek,mt6577-i2c": for MediaTek MT7623
       "mediatek,mt7629-i2c", "mediatek,mt2712-i2c": for MediaTek MT7629
       "mediatek,mt8173-i2c": for MediaTek MT8173
+      "mediatek,mt8183-i2c": for MediaTek MT8183
+      "mediatek,mt8516-i2c", "mediatek,mt2712-i2c": for MediaTek MT8516
   - reg: physical base address of the controller and dma base, length of memory
     mapped region.
   - interrupts: interrupt number to the cpu.
   - clock-div: the fixed value for frequency divider of clock source in i2c
     module. Each IC may be different.
   - clocks: clock name from clock manager
-  - clock-names: Must include "main" and "dma", if enable have-pmic need include
+  - clock-names: Must include "main" and "dma", "arb" is for multi-master that
+    one bus has more than two i2c controllers, if enable have-pmic need include
     "pmic" extra.
 
 Optional properties:

Documentation/devicetree/bindings/i2c/i2c-riic.txt

 Device tree configuration for Renesas RIIC driver
 
 Required properties:
-- compatible      : "renesas,riic-<soctype>". "renesas,riic-rz" as fallback
+- compatible      :
+	"renesas,riic-r7s72100" if the device is a part of a R7S72100 SoC.
+	"renesas,riic-r7s9210" if the device is a part of a R7S9210 SoC.
+	"renesas,riic-rz" for a generic RZ/A compatible device.
 - reg             : address start and address range size of device
 - interrupts      : 8 interrupts (TEI, RI, TI, SPI, STI, NAKI, ALI, TMOI)
 - clock-frequency : frequency of bus clock in Hz

Documentation/devicetree/bindings/i2c/i2c-stm32.txt

 * I2C controller embedded in STMicroelectronics STM32 I2C platform
 
-Required properties :
-- compatible : Must be one of the following
+Required properties:
+- compatible: Must be one of the following
   - "st,stm32f4-i2c"
   - "st,stm32f7-i2c"
-- reg : Offset and length of the register set for the device
-- interrupts : Must contain the interrupt id for I2C event and then the
+- reg: Offset and length of the register set for the device
+- interrupts: Must contain the interrupt id for I2C event and then the
   interrupt id for I2C error.
 - resets: Must contain the phandle to the reset controller.
 - clocks: Must contain the input clock of the I2C instance.
@@ -14,25 +14,26 @@ Required properties :
 - #address-cells = <1>;
 - #size-cells = <0>;
 
-Optional properties :
-- clock-frequency : Desired I2C bus clock frequency in Hz. If not specified,
+Optional properties:
+- clock-frequency: Desired I2C bus clock frequency in Hz. If not specified,
   the default 100 kHz frequency will be used.
   For STM32F4 SoC Standard-mode and Fast-mode are supported, possible values are
   100000 and 400000.
-  For STM32F7 SoC, Standard-mode, Fast-mode and Fast-mode Plus are supported,
-  possible values are 100000, 400000 and 1000000.
-- i2c-scl-rising-time-ns : Only for STM32F7, I2C SCL Rising time for the board
-  (default: 25)
-- i2c-scl-falling-time-ns : Only for STM32F7, I2C SCL Falling time for the board
-  (default: 10)
+  For STM32F7, STM32H7 and STM32MP1 SoCs, Standard-mode, Fast-mode and Fast-mode
+  Plus are supported, possible values are 100000, 400000 and 1000000.
+- i2c-scl-rising-time-ns: I2C SCL Rising time for the board (default: 25)
+  For STM32F7, STM32H7 and STM32MP1 only.
+- i2c-scl-falling-time-ns: I2C SCL Falling time for the board (default: 10)
+  For STM32F7, STM32H7 and STM32MP1 only.
   I2C Timings are derived from these 2 values
-- st,syscfg-fmp:  Only for STM32F7, use to set Fast Mode Plus bit within SYSCFG
-  whether Fast Mode Plus speed is selected by slave.
-	1st cell : phandle to syscfg
-	2nd cell : register offset within SYSCFG
-	3rd cell : register bitmask for FMP bit
+- st,syscfg-fmp: Use to set Fast Mode Plus bit within SYSCFG when Fast Mode
+  Plus speed is selected by slave.
+	1st cell: phandle to syscfg
+	2nd cell: register offset within SYSCFG
+	3rd cell: register bitmask for FMP bit
+  For STM32F7, STM32H7 and STM32MP1 only.
 
-Example :
+Example:
 
 	i2c@40005400 {
 		compatible = "st,stm32f4-i2c";

Documentation/i2c/busses/i2c-amd-mp2

+Kernel driver i2c-amd-mp2
+
+Supported adapters:
+  * AMD MP2 PCIe interface
+
+Datasheet: not publicly available.
+
+Authors:
+	Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
+	Nehal Shah <nehal-bakulchandra.shah@amd.com>
+	Elie Morisse <syniurge@gmail.com>
+
+Description
+-----------
+
+The MP2 is an ARM processor programmed as an I2C controller and communicating
+with the x86 host through PCI.
+
+If you see something like this:
+
+03:00.7 MP2 I2C controller: Advanced Micro Devices, Inc. [AMD] Device 15e6
+
+in your 'lspci -v', then this driver is for your device.

Documentation/i2c/busses/i2c-piix4

@@ -15,6 +15,8 @@ Supported adapters:
     http://support.amd.com/us/Embedded_TechDocs/44413.pdf
   * AMD Hudson-2, ML, CZ
     Datasheet: Not publicly available
+  * Hygon CZ
+    Datasheet: Not publicly available
   * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
     Datasheet: Publicly available at the SMSC website http://www.smsc.com
 

MAINTAINERS

@@ -826,6 +826,14 @@ F:	drivers/gpu/drm/amd/include/vi_structs.h
 F:	drivers/gpu/drm/amd/include/v9_structs.h
 F:	include/uapi/linux/kfd_ioctl.h
 
+AMD MP2 I2C DRIVER
+M:	Elie Morisse <syniurge@gmail.com>
+M:	Nehal Shah <nehal-bakulchandra.shah@amd.com>
+M:	Shyam Sundar S K <shyam-sundar.s-k@amd.com>
+L:	linux-i2c@vger.kernel.org
+S:	Maintained
+F:	drivers/i2c/busses/i2c-amd-mp2*
+
 AMD POWERPLAY
 M:	Rex Zhu <rex.zhu@amd.com>
 M:	Evan Quan <evan.quan@amd.com>
@@ -2582,7 +2590,7 @@ F:	include/linux/dmaengine.h
 F:	include/linux/async_tx.h
 
 AT24 EEPROM DRIVER
-M:	Bartosz Golaszewski <brgl@bgdev.pl>
+M:	Bartosz Golaszewski <bgolaszewski@baylibre.com>
 L:	linux-i2c@vger.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git
 S:	Maintained
@@ -10207,7 +10215,8 @@ MICROCHIP I2C DRIVER
 M:	Ludovic Desroches <ludovic.desroches@microchip.com>
 L:	linux-i2c@vger.kernel.org
 S:	Supported
-F:	drivers/i2c/busses/i2c-at91.c
+F:	drivers/i2c/busses/i2c-at91.h
+F:	drivers/i2c/busses/i2c-at91-*.c
 
 MICROCHIP ISC DRIVER
 M:	Eugen Hristev <eugen.hristev@microchip.com>

drivers/i2c/algos/i2c-algo-bit.c

@@ -603,6 +603,23 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 	return ret;
 }
 
+/*
+ * We print a warning when we are not flagged to support atomic transfers but
+ * will try anyhow. That's what the I2C core would do as well. Sadly, we can't
+ * modify the algorithm struct at probe time because this struct is exported
+ * 'const'.
+ */
+static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[],
+			   int num)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	if (!adap->can_do_atomic)
+		dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n");
+
+	return bit_xfer(i2c_adap, msgs, num);
+}
+
 static u32 bit_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL |
@@ -615,8 +632,9 @@ static u32 bit_func(struct i2c_adapter *adap)
 /* -----exported algorithm data: -------------------------------------	*/
 
 const struct i2c_algorithm i2c_bit_algo = {
-	.master_xfer	= bit_xfer,
-	.functionality	= bit_func,
+	.master_xfer = bit_xfer,
+	.master_xfer_atomic = bit_xfer_atomic,
+	.functionality = bit_func,
 };
 EXPORT_SYMBOL(i2c_bit_algo);
 

drivers/i2c/busses/Kconfig

@@ -77,6 +77,16 @@ config I2C_AMD8111
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-amd8111.
 
+config I2C_AMD_MP2
+	tristate "AMD MP2 PCIe"
+	depends on PCI && ACPI
+	help
+	  If you say yes to this option, support will be included for the AMD
+	  MP2 PCIe I2C adapter.
+
+	  This driver can also be built as modules.  If so, the modules will
+	  be called i2c-amd-mp2-pci and i2c-amd-mp2-plat.
+
 config I2C_HIX5HD2
 	tristate "Hix5hd2 high-speed I2C driver"
 	depends on ARCH_HISI || ARCH_HIX5HD2 || COMPILE_TEST
@@ -176,6 +186,7 @@ config I2C_PIIX4
 	    AMD Hudson-2
 	    AMD ML
 	    AMD CZ
+	    Hygon CZ
 	    Serverworks OSB4
 	    Serverworks CSB5
 	    Serverworks CSB6
@@ -388,6 +399,19 @@ config I2C_AT91
 	  the latency to fill the transmission register is too long. If you
 	  are facing this situation, use the i2c-gpio driver.
 
+config I2C_AT91_SLAVE_EXPERIMENTAL
+	tristate "Microchip AT91 I2C experimental slave mode"
+	depends on I2C_AT91
+	select I2C_SLAVE
+	help
+	  If you say yes to this option, support for the slave mode will be
+	  added. Caution: do not use it for production. This feature has not
+	  been tested in a heavy way, help wanted.
+	  There are known bugs:
+	    - It can hang, on a SAMA5D4, after several transfers.
+	    - There are some mismtaches with a SAMA5D4 as slave and a SAMA5D2 as
+	    master.
+
 config I2C_AU1550
 	tristate "Au1550/Au1200/Au1300 SMBus interface"
 	depends on MIPS_ALCHEMY
@@ -425,6 +449,7 @@ config I2C_BCM_IPROC
 	tristate "Broadcom iProc I2C controller"
 	depends on ARCH_BCM_IPROC || COMPILE_TEST
 	default ARCH_BCM_IPROC
+	select I2C_SLAVE
 	help
 	  If you say yes to this option, support will be included for the
 	  Broadcom iProc I2C controller.

drivers/i2c/busses/Makefile

@@ -33,8 +33,13 @@ obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
 obj-$(CONFIG_I2C_ALTERA)	+= i2c-altera.o
+obj-$(CONFIG_I2C_AMD_MP2)	+= i2c-amd-mp2-pci.o i2c-amd-mp2-plat.o
 obj-$(CONFIG_I2C_ASPEED)	+= i2c-aspeed.o
 obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
+i2c-at91-objs			:= i2c-at91-core.o i2c-at91-master.o
+ifeq ($(CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL),y)
+	i2c-at91-objs		+= i2c-at91-slave.o
+endif
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
 obj-$(CONFIG_I2C_AXXIA)		+= i2c-axxia.o
 obj-$(CONFIG_I2C_BCM2835)	+= i2c-bcm2835.o

drivers/i2c/busses/i2c-amd-mp2-plat.c

+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * AMD MP2 platform driver
+ *
+ * Setup the I2C adapters enumerated in the ACPI namespace.
+ * MP2 controllers have 2 separate busses, up to 2 I2C adapters may be listed.
+ *
+ * Authors: Nehal Bakulchandra Shah <Nehal-bakulchandra.shah@amd.com>
+ *          Elie Morisse <syniurge@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "i2c-amd-mp2.h"
+
+#define AMD_MP2_I2C_MAX_RW_LENGTH ((1 << 12) - 1)
+#define AMD_I2C_TIMEOUT (msecs_to_jiffies(250))
+
+/**
+ * struct amd_i2c_dev - MP2 bus/i2c adapter context
+ * @common: shared context with the MP2 PCI driver
+ * @pdev: platform driver node
+ * @adap: i2c adapter
+ * @cmd_complete: xfer completion object
+ */
+struct amd_i2c_dev {
+	struct amd_i2c_common common;
+	struct platform_device *pdev;
+	struct i2c_adapter adap;
+	struct completion cmd_complete;
+};
+
+#define amd_i2c_dev_common(__common) \
+	container_of(__common, struct amd_i2c_dev, common)
+
+static int i2c_amd_dma_map(struct amd_i2c_common *i2c_common)
+{
+	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+	enum dma_data_direction dma_direction =
+			i2c_common->msg->flags & I2C_M_RD ?
+			DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+	i2c_common->dma_buf = i2c_get_dma_safe_msg_buf(i2c_common->msg, 0);
+	i2c_common->dma_addr = dma_map_single(dev_pci, i2c_common->dma_buf,
+					      i2c_common->msg->len,
+					      dma_direction);
+
+	if (unlikely(dma_mapping_error(dev_pci, i2c_common->dma_addr))) {
+		dev_err(&i2c_dev->pdev->dev,
+			"Error while mapping dma buffer %p\n",
+			i2c_common->dma_buf);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void i2c_amd_dma_unmap(struct amd_i2c_common *i2c_common)
+{
+	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
+	enum dma_data_direction dma_direction =
+			i2c_common->msg->flags & I2C_M_RD ?
+			DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+	dma_unmap_single(dev_pci, i2c_common->dma_addr,
+			 i2c_common->msg->len, dma_direction);
+
+	i2c_put_dma_safe_msg_buf(i2c_common->dma_buf, i2c_common->msg, true);
+}
+
+static void i2c_amd_start_cmd(struct amd_i2c_dev *i2c_dev)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	reinit_completion(&i2c_dev->cmd_complete);
+	i2c_common->cmd_success = false;
+}
+
+static void i2c_amd_cmd_completion(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+	union i2c_event *event = &i2c_common->eventval;
+
+	if (event->r.status == i2c_readcomplete_event)
+		dev_dbg(&i2c_dev->pdev->dev, "%s readdata:%*ph\n",
+			__func__, event->r.length,
+			i2c_common->msg->buf);
+
+	complete(&i2c_dev->cmd_complete);
+}
+
+static int i2c_amd_check_cmd_completion(struct amd_i2c_dev *i2c_dev)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+	unsigned long timeout;
+
+	timeout = wait_for_completion_timeout(&i2c_dev->cmd_complete,
+					      i2c_dev->adap.timeout);
+
+	if ((i2c_common->reqcmd == i2c_read ||
+	     i2c_common->reqcmd == i2c_write) &&
+	    i2c_common->msg->len > 32)
+		i2c_amd_dma_unmap(i2c_common);
+
+	if (timeout == 0) {
+		amd_mp2_rw_timeout(i2c_common);
+		return -ETIMEDOUT;
+	}
+
+	amd_mp2_process_event(i2c_common);
+
+	if (!i2c_common->cmd_success)
+		return -EIO;
+
+	return 0;
+}
+
+static int i2c_amd_enable_set(struct amd_i2c_dev *i2c_dev, bool enable)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_amd_start_cmd(i2c_dev);
+	amd_mp2_bus_enable_set(i2c_common, enable);
+
+	return i2c_amd_check_cmd_completion(i2c_dev);
+}
+
+static int i2c_amd_xfer_msg(struct amd_i2c_dev *i2c_dev, struct i2c_msg *pmsg)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_amd_start_cmd(i2c_dev);
+	i2c_common->msg = pmsg;
+
+	if (pmsg->len > 32)
+		if (i2c_amd_dma_map(i2c_common))
+			return -EIO;
+
+	if (pmsg->flags & I2C_M_RD)
+		amd_mp2_rw(i2c_common, i2c_read);
+	else
+		amd_mp2_rw(i2c_common, i2c_write);
+
+	return i2c_amd_check_cmd_completion(i2c_dev);
+}
+
+static int i2c_amd_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct amd_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+	int i;
+	struct i2c_msg *pmsg;
+	int err;
+
+	/* the adapter might have been deleted while waiting for the bus lock */
+	if (unlikely(!i2c_dev->common.mp2_dev))
+		return -EINVAL;
+
+	amd_mp2_pm_runtime_get(i2c_dev->common.mp2_dev);
+
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		err = i2c_amd_xfer_msg(i2c_dev, pmsg);
+		if (err)
+			break;
+	}
+
+	amd_mp2_pm_runtime_put(i2c_dev->common.mp2_dev);
+	return err ? err : num;
+}
+
+static u32 i2c_amd_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm i2c_amd_algorithm = {
+	.master_xfer = i2c_amd_xfer,
+	.functionality = i2c_amd_func,
+};
+
+#ifdef CONFIG_PM
+static int i2c_amd_suspend(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+
+	i2c_amd_enable_set(i2c_dev, false);
+	return 0;
+}
+
+static int i2c_amd_resume(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+
+	return i2c_amd_enable_set(i2c_dev, true);
+}
+#endif
+
+static enum speed_enum i2c_amd_get_bus_speed(struct platform_device *pdev)
+{
+	u32 acpi_speed;
+	int i;
+	static const u32 supported_speeds[] = {
+		0, 100000, 400000, 1000000, 1400000, 3400000
+	};
+
+	acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
+	/* round down to the lowest standard speed */
+	for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) {
+		if (acpi_speed < supported_speeds[i])
+			break;
+	}
+	acpi_speed = supported_speeds[i - 1];
+
+	switch (acpi_speed) {
+	case 100000:
+		return speed100k;
+	case 400000:
+		return speed400k;
+	case 1000000:
+		return speed1000k;
+	case 1400000:
+		return speed1400k;
+	case 3400000:
+		return speed3400k;
+	default:
+		return speed400k;
+	}
+}
+
+static const struct i2c_adapter_quirks amd_i2c_dev_quirks = {
+	.max_read_len = AMD_MP2_I2C_MAX_RW_LENGTH,
+	.max_write_len = AMD_MP2_I2C_MAX_RW_LENGTH,
+};
+
+static int i2c_amd_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct amd_i2c_dev *i2c_dev;
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	struct acpi_device *adev;
+	struct amd_mp2_dev *mp2_dev;
+	const char *uid;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return -ENODEV;
+
+	/* The ACPI namespace doesn't contain information about which MP2 PCI
+	 * device an AMDI0011 ACPI device is related to, so assume that there's
+	 * only one MP2 PCI device per system.
+	 */
+	mp2_dev = amd_mp2_find_device();
+	if (!mp2_dev || !mp2_dev->probed)
+		/* The MP2 PCI device should get probed later */
+		return -EPROBE_DEFER;
+
+	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
+	if (!i2c_dev)
+		return -ENOMEM;
+
+	i2c_dev->common.mp2_dev = mp2_dev;
+	i2c_dev->pdev = pdev;
+	platform_set_drvdata(pdev, i2c_dev);
+
+	i2c_dev->common.cmd_completion = &i2c_amd_cmd_completion;
+#ifdef CONFIG_PM
+	i2c_dev->common.suspend = &i2c_amd_suspend;
+	i2c_dev->common.resume = &i2c_amd_resume;
+#endif
+
+	uid = adev->pnp.unique_id;
+	if (!uid) {
+		dev_err(&pdev->dev, "missing UID/bus id!\n");
+		return -EINVAL;
+	} else if (strcmp(uid, "0") == 0) {
+		i2c_dev->common.bus_id = 0;
+	} else if (strcmp(uid, "1") == 0) {
+		i2c_dev->common.bus_id = 1;
+	} else {
+		dev_err(&pdev->dev, "incorrect UID/bus id \"%s\"!\n", uid);
+		return -EINVAL;
+	}
+	dev_dbg(&pdev->dev, "bus id is %u\n", i2c_dev->common.bus_id);
+
+	/* Register the adapter */
+	amd_mp2_pm_runtime_get(mp2_dev);
+
+	i2c_dev->common.reqcmd = i2c_none;
+	if (amd_mp2_register_cb(&i2c_dev->common))
+		return -EINVAL;
+	device_link_add(&i2c_dev->pdev->dev, &mp2_dev->pci_dev->dev,
+			DL_FLAG_AUTOREMOVE_CONSUMER);
+
+	i2c_dev->common.i2c_speed = i2c_amd_get_bus_speed(pdev);
+
+	/* Setup i2c adapter description */
+	i2c_dev->adap.owner = THIS_MODULE;
+	i2c_dev->adap.algo = &i2c_amd_algorithm;
+	i2c_dev->adap.quirks = &amd_i2c_dev_quirks;
+	i2c_dev->adap.dev.parent = &pdev->dev;
+	i2c_dev->adap.algo_data = i2c_dev;
+	i2c_dev->adap.timeout = AMD_I2C_TIMEOUT;
+	ACPI_COMPANION_SET(&i2c_dev->adap.dev, ACPI_COMPANION(&pdev->dev));
+	i2c_dev->adap.dev.of_node = pdev->dev.of_node;
+	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
+		 "AMD MP2 i2c bus %u", i2c_dev->common.bus_id);
+	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
+
+	init_completion(&i2c_dev->cmd_complete);
+
+	/* Enable the bus */
+	if (i2c_amd_enable_set(i2c_dev, true))
+		dev_err(&pdev->dev, "initial bus enable failed\n");
+
+	/* Attach to the i2c layer */
+	ret = i2c_add_adapter(&i2c_dev->adap);
+
+	amd_mp2_pm_runtime_put(mp2_dev);
+
+	if (ret < 0)
+		dev_err(&pdev->dev, "i2c add adapter failed = %d\n", ret);
+
+	return ret;
+}
+
+static int i2c_amd_remove(struct platform_device *pdev)
+{
+	struct amd_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_lock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);
+
+	i2c_amd_enable_set(i2c_dev, false);
+	amd_mp2_unregister_cb(i2c_common);
+	i2c_common->mp2_dev = NULL;
+
+	i2c_unlock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);
+
+	i2c_del_adapter(&i2c_dev->adap);
+	return 0;
+}
+
+static const struct acpi_device_id i2c_amd_acpi_match[] = {
+	{ "AMDI0011" },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, i2c_amd_acpi_match);
+
+static struct platform_driver i2c_amd_plat_driver = {
+	.probe = i2c_amd_probe,
+	.remove = i2c_amd_remove,
+	.driver = {
+		.name = "i2c_amd_mp2",
+		.acpi_match_table = ACPI_PTR(i2c_amd_acpi_match),
+	},
+};
+module_platform_driver(i2c_amd_plat_driver);
+
+MODULE_DESCRIPTION("AMD(R) MP2 I2C Platform Driver");
+MODULE_AUTHOR("Nehal Shah <nehal-bakulchandra.shah@amd.com>");
+MODULE_AUTHOR("Elie Morisse <syniurge@gmail.com>");
+MODULE_LICENSE("Dual BSD/GPL");

drivers/i2c/busses/i2c-amd-mp2.h

+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
+/*
+ * AMD MP2 I2C adapter driver
+ *
+ * Authors: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
+ *          Elie Morisse <syniurge@gmail.com>
+ */
+
+#ifndef I2C_AMD_PCI_MP2_H
+#define I2C_AMD_PCI_MP2_H
+
+#include <linux/i2c.h>
+#include <linux/pci.h>
+#include <linux/pm_runtime.h>
+
+#define PCI_DEVICE_ID_AMD_MP2	0x15E6
+
+struct amd_i2c_common;
+struct amd_mp2_dev;
+
+enum {
+	/* MP2 C2P Message Registers */
+	AMD_C2P_MSG0 = 0x10500,			/* MP2 Message for I2C0 */
+	AMD_C2P_MSG1 = 0x10504,			/* MP2 Message for I2C1 */
+	AMD_C2P_MSG2 = 0x10508,			/* DRAM Address Lo / Data 0 */
+	AMD_C2P_MSG3 = 0x1050c,			/* DRAM Address HI / Data 1 */
+	AMD_C2P_MSG4 = 0x10510,			/* Data 2 */
+	AMD_C2P_MSG5 = 0x10514,			/* Data 3 */
+	AMD_C2P_MSG6 = 0x10518,			/* Data 4 */
+	AMD_C2P_MSG7 = 0x1051c,			/* Data 5 */
+	AMD_C2P_MSG8 = 0x10520,			/* Data 6 */
+	AMD_C2P_MSG9 = 0x10524,			/* Data 7 */
+
+	/* MP2 P2C Message Registers */
+	AMD_P2C_MSG0 = 0x10680,			/* Do not use */
+	AMD_P2C_MSG1 = 0x10684,			/* I2C0 interrupt register */
+	AMD_P2C_MSG2 = 0x10688,			/* I2C1 interrupt register */
+	AMD_P2C_MSG3 = 0x1068C,			/* MP2 debug info */
+	AMD_P2C_MSG_INTEN = 0x10690,		/* MP2 interrupt gen register */
+	AMD_P2C_MSG_INTSTS = 0x10694,		/* Interrupt status */
+};
+
+/* Command register data structures */
+
+#define i2c_none (-1)
+enum i2c_cmd {
+	i2c_read = 0,
+	i2c_write,
+	i2c_enable,
+	i2c_disable,
+	number_of_sensor_discovered,
+	is_mp2_active,
+	invalid_cmd = 0xF,
+};
+
+enum speed_enum {
+	speed100k = 0,
+	speed400k = 1,
+	speed1000k = 2,
+	speed1400k = 3,
+	speed3400k = 4
+};
+
+enum mem_type {
+	use_dram = 0,
+	use_c2pmsg = 1,
+};
+
+/**
+ * union i2c_cmd_base : bit access of C2P commands
+ * @i2c_cmd: bit 0..3 i2c R/W command
+ * @bus_id: bit 4..7 i2c bus index
+ * @slave_addr: bit 8..15 slave address
+ * @length: bit 16..27 read/write length
+ * @i2c_speed: bit 28..30 bus speed
+ * @mem_type: bit 31 0-DRAM; 1-C2P msg o/p
+ */
+union i2c_cmd_base {
+	u32 ul;
+	struct {
+		enum i2c_cmd i2c_cmd : 4;
+		u8 bus_id : 4;
+		u32 slave_addr : 8;
+		u32 length : 12;
+		enum speed_enum i2c_speed : 3;
+		enum mem_type mem_type : 1;
+	} s;
+};
+
+enum response_type {
+	invalid_response = 0,
+	command_success = 1,
+	command_failed = 2,
+};
+
+enum status_type {
+	i2c_readcomplete_event = 0,
+	i2c_readfail_event = 1,
+	i2c_writecomplete_event = 2,
+	i2c_writefail_event = 3,
+	i2c_busenable_complete = 4,
+	i2c_busenable_failed = 5,
+	i2c_busdisable_complete = 6,
+	i2c_busdisable_failed = 7,
+	invalid_data_length = 8,
+	invalid_slave_address = 9,
+	invalid_i2cbus_id = 10,
+	invalid_dram_addr = 11,
+	invalid_command = 12,
+	mp2_active = 13,
+	numberof_sensors_discovered_resp = 14,
+	i2c_bus_notinitialized
+};
+
+/**
+ * union i2c_event : bit access of P2C events
+ * @response: bit 0..1 i2c response type
+ * @status: bit 2..6 status_type
+ * @mem_type: bit 7 0-DRAM; 1-C2P msg o/p
+ * @bus_id: bit 8..11 i2c bus id
+ * @length: bit 12..23 message length
+ * @slave_addr: bit 24-31 slave address
+ */
+union i2c_event {
+	u32 ul;
+	struct {
+		enum response_type response : 2;
+		enum status_type status : 5;
+		enum mem_type mem_type : 1;
+		u8 bus_id : 4;
+		u32 length : 12;
+		u32 slave_addr : 8;
+	} r;
+};
+
+/**
+ * struct amd_i2c_common - per bus/i2c adapter context, shared
+ *	between the pci and the platform driver
+ * @eventval: MP2 event value set by the IRQ handler
+ * @mp2_dev: MP2 pci device this adapter is part of
+ * @msg: i2c message
+ * @cmd_completion: function called by the IRQ handler to signal
+ *		    the platform driver
+ * @reqcmd: requested i2c command type
+ * @cmd_success: set to true if the MP2 responded to a command with
+ *		 the expected status and response type
+ * @bus_id: bus index
+ * @i2c_speed: i2c bus speed determined by the slowest slave
+ * @dma_buf: if msg length > 32, holds the DMA buffer virtual address
+ * @dma_addr: if msg length > 32, holds the DMA buffer address
+ */
+struct amd_i2c_common {
+	union i2c_event eventval;
+	struct amd_mp2_dev *mp2_dev;
+	struct i2c_msg *msg;
+	void (*cmd_completion)(struct amd_i2c_common *i2c_common);
+	enum i2c_cmd reqcmd;
+	u8 cmd_success;
+	u8 bus_id;
+	enum speed_enum i2c_speed;
+	u8 *dma_buf;
+	dma_addr_t dma_addr;
+#ifdef CONFIG_PM
+	int (*suspend)(struct amd_i2c_common *i2c_common);
+	int (*resume)(struct amd_i2c_common *i2c_common);
+#endif /* CONFIG_PM */
+};
+
+/**
+ * struct amd_mp2_dev - per PCI device context
+ * @pci_dev: PCI driver node
+ * @busses: MP2 devices may have up to two busses,
+ *	    each bus corresponding to an i2c adapter
+ * @mmio: iommapped registers
+ * @c2p_lock: controls access to the C2P mailbox shared between
+ *	      the two adapters
+ * @c2p_lock_busid: id of the adapter which locked c2p_lock
+ */
+struct amd_mp2_dev {
+	struct pci_dev *pci_dev;
+	struct amd_i2c_common *busses[2];
+	void __iomem *mmio;
+	struct mutex c2p_lock;
+	u8 c2p_lock_busid;
+	unsigned int probed;
+};
+
+#define ndev_pdev(ndev) ((ndev)->pci_dev)
+#define ndev_name(ndev) pci_name(ndev_pdev(ndev))
+#define ndev_dev(ndev) (&ndev_pdev(ndev)->dev)
+#define work_amd_i2c_common(__work) \
+	container_of(__work, struct amd_i2c_common, work.work)
+
+/* PCIe communication driver */
+
+int amd_mp2_rw(struct amd_i2c_common *i2c_common, enum i2c_cmd reqcmd);
+int amd_mp2_bus_enable_set(struct amd_i2c_common *i2c_common, bool enable);
+
+void amd_mp2_process_event(struct amd_i2c_common *i2c_common);
+
+void amd_mp2_rw_timeout(struct amd_i2c_common *i2c_common);
+
+int amd_mp2_register_cb(struct amd_i2c_common *i2c_common);
+int amd_mp2_unregister_cb(struct amd_i2c_common *i2c_common);
+
+struct amd_mp2_dev *amd_mp2_find_device(void);
+
+static inline void amd_mp2_pm_runtime_get(struct amd_mp2_dev *mp2_dev)
+{
+	pm_runtime_get_sync(&mp2_dev->pci_dev->dev);
+}
+
+static inline void amd_mp2_pm_runtime_put(struct amd_mp2_dev *mp2_dev)
+{
+	pm_runtime_mark_last_busy(&mp2_dev->pci_dev->dev);
+	pm_runtime_put_autosuspend(&mp2_dev->pci_dev->dev);
+}
+
+#endif

drivers/i2c/busses/i2c-at91-core.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pinctrl/consumer.h>
+
+#include "i2c-at91.h"
+
+unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
+{
+	return readl_relaxed(dev->base + reg);
+}
+
+void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
+{
+	writel_relaxed(val, dev->base + reg);
+}
+
+void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_INT_MASK);
+}
+
+void at91_twi_irq_save(struct at91_twi_dev *dev)
+{
+	dev->imr = at91_twi_read(dev, AT91_TWI_IMR) & AT91_TWI_INT_MASK;
+	at91_disable_twi_interrupts(dev);
+}
+
+void at91_twi_irq_restore(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IER, dev->imr);
+}
+
+void at91_init_twi_bus(struct at91_twi_dev *dev)
+{
+	at91_disable_twi_interrupts(dev);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+	if (dev->slave_detected)
+		at91_init_twi_bus_slave(dev);
+	else
+		at91_init_twi_bus_master(dev);
+}
+
+static struct at91_twi_pdata at91rm9200_config = {
+	.clk_max_div = 5,
+	.clk_offset = 3,
+	.has_unre_flag = true,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9261_config = {
+	.clk_max_div = 5,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9260_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9g20_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9g10_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static const struct platform_device_id at91_twi_devtypes[] = {
+	{
+		.name = "i2c-at91rm9200",
+		.driver_data = (unsigned long) &at91rm9200_config,
+	}, {
+		.name = "i2c-at91sam9261",
+		.driver_data = (unsigned long) &at91sam9261_config,
+	}, {
+		.name = "i2c-at91sam9260",
+		.driver_data = (unsigned long) &at91sam9260_config,
+	}, {
+		.name = "i2c-at91sam9g20",
+		.driver_data = (unsigned long) &at91sam9g20_config,
+	}, {
+		.name = "i2c-at91sam9g10",
+		.driver_data = (unsigned long) &at91sam9g10_config,
+	}, {
+		/* sentinel */
+	}
+};
+
+#if defined(CONFIG_OF)
+static struct at91_twi_pdata at91sam9x5_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata sama5d4_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = true,
+};
+
+static struct at91_twi_pdata sama5d2_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = true,
+	.has_alt_cmd = true,
+	.has_hold_field = true,
+};
+
+static const struct of_device_id atmel_twi_dt_ids[] = {
+	{
+		.compatible = "atmel,at91rm9200-i2c",
+		.data = &at91rm9200_config,
+	}, {
+		.compatible = "atmel,at91sam9260-i2c",
+		.data = &at91sam9260_config,
+	}, {
+		.compatible = "atmel,at91sam9261-i2c",
+		.data = &at91sam9261_config,
+	}, {
+		.compatible = "atmel,at91sam9g20-i2c",
+		.data = &at91sam9g20_config,
+	}, {
+		.compatible = "atmel,at91sam9g10-i2c",
+		.data = &at91sam9g10_config,
+	}, {
+		.compatible = "atmel,at91sam9x5-i2c",
+		.data = &at91sam9x5_config,
+	}, {
+		.compatible = "atmel,sama5d4-i2c",
+		.data = &sama5d4_config,
+	}, {
+		.compatible = "atmel,sama5d2-i2c",
+		.data = &sama5d2_config,
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
+#endif
+
+static struct at91_twi_pdata *at91_twi_get_driver_data(
+					struct platform_device *pdev)
+{
+	if (pdev->dev.of_node) {
+		const struct of_device_id *match;
+		match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node);
+		if (!match)
+			return NULL;
+		return (struct at91_twi_pdata *)match->data;
+	}
+	return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;
+}
+
+static int at91_twi_probe(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev;
+	struct resource *mem;
+	int rc;
+	u32 phy_addr;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->dev = &pdev->dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENODEV;
+	phy_addr = mem->start;
+
+	dev->pdata = at91_twi_get_driver_data(pdev);
+	if (!dev->pdata)
+		return -ENODEV;
+
+	dev->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(dev->base))
+		return PTR_ERR(dev->base);
+
+	dev->irq = platform_get_irq(pdev, 0);
+	if (dev->irq < 0)
+		return dev->irq;
+
+	platform_set_drvdata(pdev, dev);
+
+	dev->clk = devm_clk_get(dev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(dev->dev, "no clock defined\n");
+		return -ENODEV;
+	}
+	clk_prepare_enable(dev->clk);
+
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
+	i2c_set_adapdata(&dev->adapter, dev);
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_DEPRECATED;
+	dev->adapter.dev.parent = dev->dev;
+	dev->adapter.nr = pdev->id;
+	dev->adapter.timeout = AT91_I2C_TIMEOUT;
+	dev->adapter.dev.of_node = pdev->dev.of_node;
+
+	dev->slave_detected = i2c_detect_slave_mode(&pdev->dev);
+
+	if (dev->slave_detected)
+		rc = at91_twi_probe_slave(pdev, phy_addr, dev);
+	else
+		rc = at91_twi_probe_master(pdev, phy_addr, dev);
+	if (rc)
+		return rc;
+
+	at91_init_twi_bus(dev);
+
+	pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(dev->dev);
+	pm_runtime_set_active(dev->dev);
+	pm_runtime_enable(dev->dev);
+
+	rc = i2c_add_numbered_adapter(&dev->adapter);
+	if (rc) {
+		clk_disable_unprepare(dev->clk);
+
+		pm_runtime_disable(dev->dev);
+		pm_runtime_set_suspended(dev->dev);
+
+		return rc;
+	}
+
+	dev_info(dev->dev, "AT91 i2c bus driver (hw version: %#x).\n",
+		 at91_twi_read(dev, AT91_TWI_VER));
+	return 0;
+}
+
+static int at91_twi_remove(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&dev->adapter);
+	clk_disable_unprepare(dev->clk);
+
+	pm_runtime_disable(dev->dev);
+	pm_runtime_set_suspended(dev->dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+static int at91_twi_runtime_suspend(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(twi_dev->clk);
+
+	pinctrl_pm_select_sleep_state(dev);
+
+	return 0;
+}
+
+static int at91_twi_runtime_resume(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	pinctrl_pm_select_default_state(dev);
+
+	return clk_prepare_enable(twi_dev->clk);
+}
+
+static int at91_twi_suspend_noirq(struct device *dev)
+{
+	if (!pm_runtime_status_suspended(dev))
+		at91_twi_runtime_suspend(dev);
+
+	return 0;
+}
+
+static int at91_twi_resume_noirq(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+	int ret;
+
+	if (!pm_runtime_status_suspended(dev)) {
+		ret = at91_twi_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	pm_runtime_mark_last_busy(dev);
+	pm_request_autosuspend(dev);
+
+	at91_init_twi_bus(twi_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops at91_twi_pm = {
+	.suspend_noirq	= at91_twi_suspend_noirq,
+	.resume_noirq	= at91_twi_resume_noirq,
+	.runtime_suspend	= at91_twi_runtime_suspend,
+	.runtime_resume		= at91_twi_runtime_resume,
+};
+
+#define at91_twi_pm_ops (&at91_twi_pm)
+#else
+#define at91_twi_pm_ops NULL
+#endif
+
+static struct platform_driver at91_twi_driver = {
+	.probe		= at91_twi_probe,
+	.remove		= at91_twi_remove,
+	.id_table	= at91_twi_devtypes,
+	.driver		= {
+		.name	= "at91_i2c",
+		.of_match_table = of_match_ptr(atmel_twi_dt_ids),
+		.pm	= at91_twi_pm_ops,
+	},
+};
+
+static int __init at91_twi_init(void)
+{
+	return platform_driver_register(&at91_twi_driver);
+}
+
+static void __exit at91_twi_exit(void)
+{
+	platform_driver_unregister(&at91_twi_driver);
+}
+
+subsys_initcall(at91_twi_init);
+module_exit(at91_twi_exit);
+
+MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>");
+MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:at91_i2c");

drivers/i2c/busses/i2c-at91-slave.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2017 Juergen Fitschen <me@jue.yt>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
+
+#include "i2c-at91.h"
+
+static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)
+{
+	struct at91_twi_dev *dev = dev_id;
+	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
+	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
+	u8 value;
+
+	if (!irqstatus)
+		return IRQ_NONE;
+
+	/* slave address has been detected on I2C bus */
+	if (irqstatus & AT91_TWI_SVACC) {
+		if (status & AT91_TWI_SVREAD) {
+			i2c_slave_event(dev->slave,
+					I2C_SLAVE_READ_REQUESTED, &value);
+			writeb_relaxed(value, dev->base + AT91_TWI_THR);
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_TXRDY | AT91_TWI_EOSACC);
+		} else {
+			i2c_slave_event(dev->slave,
+					I2C_SLAVE_WRITE_REQUESTED, &value);
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_RXRDY | AT91_TWI_EOSACC);
+		}
+		at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);
+	}
+
+	/* byte transmitted to remote master */
+	if (irqstatus & AT91_TWI_TXRDY) {
+		i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);
+		writeb_relaxed(value, dev->base + AT91_TWI_THR);
+	}
+
+	/* byte received from remote master */
+	if (irqstatus & AT91_TWI_RXRDY) {
+		value = readb_relaxed(dev->base + AT91_TWI_RHR);
+		i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+	}
+
+	/* master sent stop */
+	if (irqstatus & AT91_TWI_EOSACC) {
+		at91_twi_write(dev, AT91_TWI_IDR,
+			       AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);
+		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
+		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &value);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int at91_reg_slave(struct i2c_client *slave)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	if (dev->slave)
+		return -EBUSY;
+
+	if (slave->flags & I2C_CLIENT_TEN)
+		return -EAFNOSUPPORT;
+
+	/* Make sure twi_clk doesn't get turned off! */
+	pm_runtime_get_sync(dev->dev);
+
+	dev->slave = slave;
+	dev->smr = AT91_TWI_SMR_SADR(slave->addr);
+
+	at91_init_twi_bus(dev);
+	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
+
+	dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);
+
+	return 0;
+}
+
+static int at91_unreg_slave(struct i2c_client *slave)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	WARN_ON(!dev->slave);
+
+	dev_info(dev->dev, "leaving slave mode\n");
+
+	dev->slave = NULL;
+	dev->smr = 0;
+
+	at91_init_twi_bus(dev);
+
+	pm_runtime_put(dev->dev);
+
+	return 0;
+}
+
+static u32 at91_twi_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm at91_twi_algorithm_slave = {
+	.reg_slave	= at91_reg_slave,
+	.unreg_slave	= at91_unreg_slave,
+	.functionality	= at91_twi_func,
+};
+
+int at91_twi_probe_slave(struct platform_device *pdev,
+			 u32 phy_addr, struct at91_twi_dev *dev)
+{
+	int rc;
+
+	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,
+			      0, dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		return rc;
+	}
+
+	dev->adapter.algo = &at91_twi_algorithm_slave;
+
+	return 0;
+}
+
+void at91_init_twi_bus_slave(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);
+	if (dev->slave_detected && dev->smr) {
+		at91_twi_write(dev, AT91_TWI_SMR, dev->smr);
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);
+	}
+}

drivers/i2c/busses/i2c-at91.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/i2c.h>
+#include <linux/platform_data/dma-atmel.h>
+#include <linux/platform_device.h>
+
+#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
+#define AT91_I2C_DMA_THRESHOLD	8			/* enable DMA if transfer size is bigger than this threshold */
+#define AUTOSUSPEND_TIMEOUT		2000
+#define AT91_I2C_MAX_ALT_CMD_DATA_SIZE	256
+
+/* AT91 TWI register definitions */
+#define	AT91_TWI_CR		0x0000	/* Control Register */
+#define	AT91_TWI_START		BIT(0)	/* Send a Start Condition */
+#define	AT91_TWI_STOP		BIT(1)	/* Send a Stop Condition */
+#define	AT91_TWI_MSEN		BIT(2)	/* Master Transfer Enable */
+#define	AT91_TWI_MSDIS		BIT(3)	/* Master Transfer Disable */
+#define	AT91_TWI_SVEN		BIT(4)	/* Slave Transfer Enable */
+#define	AT91_TWI_SVDIS		BIT(5)	/* Slave Transfer Disable */
+#define	AT91_TWI_QUICK		BIT(6)	/* SMBus quick command */
+#define	AT91_TWI_SWRST		BIT(7)	/* Software Reset */
+#define	AT91_TWI_ACMEN		BIT(16) /* Alternative Command Mode Enable */
+#define	AT91_TWI_ACMDIS		BIT(17) /* Alternative Command Mode Disable */
+#define	AT91_TWI_THRCLR		BIT(24) /* Transmit Holding Register Clear */
+#define	AT91_TWI_RHRCLR		BIT(25) /* Receive Holding Register Clear */
+#define	AT91_TWI_LOCKCLR	BIT(26) /* Lock Clear */
+#define	AT91_TWI_FIFOEN		BIT(28) /* FIFO Enable */
+#define	AT91_TWI_FIFODIS	BIT(29) /* FIFO Disable */
+
+#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
+#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
+#define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */
+
+#define	AT91_TWI_SMR		0x0008	/* Slave Mode Register */
+#define	AT91_TWI_SMR_SADR_MAX	0x007f
+#define	AT91_TWI_SMR_SADR(x)	(((x) & AT91_TWI_SMR_SADR_MAX) << 16)
+
+#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
+
+#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
+#define	AT91_TWI_CWGR_HOLD_MAX	0x1f
+#define	AT91_TWI_CWGR_HOLD(x)	(((x) & AT91_TWI_CWGR_HOLD_MAX) << 24)
+
+#define	AT91_TWI_SR		0x0020	/* Status Register */
+#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
+#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
+#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
+#define	AT91_TWI_SVREAD		BIT(3)	/* Slave Read */
+#define	AT91_TWI_SVACC		BIT(4)	/* Slave Access */
+#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
+#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
+#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
+#define	AT91_TWI_EOSACC		BIT(11)	/* End Of Slave Access */
+#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
+
+#define	AT91_TWI_INT_MASK \
+	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \
+	| AT91_TWI_SVACC | AT91_TWI_EOSACC)
+
+#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
+#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
+#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
+#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
+#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
+
+#define	AT91_TWI_ACR		0x0040	/* Alternative Command Register */
+#define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
+#define	AT91_TWI_ACR_DIR	BIT(8)
+
+#define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
+#define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
+#define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)
+#define	AT91_TWI_FMR_RXRDYM(mode)	(((mode) & 0x3) << 4)
+#define	AT91_TWI_FMR_RXRDYM_MASK	(0x3 << 4)
+#define	AT91_TWI_ONE_DATA	0x0
+#define	AT91_TWI_TWO_DATA	0x1
+#define	AT91_TWI_FOUR_DATA	0x2
+
+#define	AT91_TWI_FLR		0x0054	/* FIFO Level Register */
+
+#define	AT91_TWI_FSR		0x0060	/* FIFO Status Register */
+#define	AT91_TWI_FIER		0x0064	/* FIFO Interrupt Enable Register */
+#define	AT91_TWI_FIDR		0x0068	/* FIFO Interrupt Disable Register */
+#define	AT91_TWI_FIMR		0x006c	/* FIFO Interrupt Mask Register */
+
+#define	AT91_TWI_VER		0x00fc	/* Version Register */
+
+struct at91_twi_pdata {
+	unsigned clk_max_div;
+	unsigned clk_offset;
+	bool has_unre_flag;
+	bool has_alt_cmd;
+	bool has_hold_field;
+	struct at_dma_slave dma_slave;
+};
+
+struct at91_twi_dma {
+	struct dma_chan *chan_rx;
+	struct dma_chan *chan_tx;
+	struct scatterlist sg[2];
+	struct dma_async_tx_descriptor *data_desc;
+	enum dma_data_direction direction;
+	bool buf_mapped;
+	bool xfer_in_progress;
+};
+
+struct at91_twi_dev {
+	struct device *dev;
+	void __iomem *base;
+	struct completion cmd_complete;
+	struct clk *clk;
+	u8 *buf;
+	size_t buf_len;
+	struct i2c_msg *msg;
+	int irq;
+	unsigned imr;
+	unsigned transfer_status;
+	struct i2c_adapter adapter;
+	unsigned twi_cwgr_reg;
+	struct at91_twi_pdata *pdata;
+	bool use_dma;
+	bool use_alt_cmd;
+	bool recv_len_abort;
+	u32 fifo_size;
+	struct at91_twi_dma dma;
+	bool slave_detected;
+#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL
+	unsigned smr;
+	struct i2c_client *slave;
+#endif
+};
+
+unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);
+void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val);
+void at91_disable_twi_interrupts(struct at91_twi_dev *dev);
+void at91_twi_irq_save(struct at91_twi_dev *dev);
+void at91_twi_irq_restore(struct at91_twi_dev *dev);
+void at91_init_twi_bus(struct at91_twi_dev *dev);
+
+void at91_init_twi_bus_master(struct at91_twi_dev *dev);
+int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr,
+			  struct at91_twi_dev *dev);
+
+#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL
+void at91_init_twi_bus_slave(struct at91_twi_dev *dev);
+int at91_twi_probe_slave(struct platform_device *pdev, u32 phy_addr,
+			 struct at91_twi_dev *dev);
+
+#else
+static inline void at91_init_twi_bus_slave(struct at91_twi_dev *dev) {}
+static inline int at91_twi_probe_slave(struct platform_device *pdev,
+				       u32 phy_addr, struct at91_twi_dev *dev)
+{
+	return -EINVAL;
+}
+
+#endif

drivers/i2c/busses/i2c-axxia.c

@@ -99,6 +99,7 @@
  * @adapter: core i2c abstraction
  * @i2c_clk: clock reference for i2c input clock
  * @bus_clk_rate: current i2c bus clock rate
+ * @last: a flag indicating is this is last message in transfer
  */
 struct axxia_i2c_dev {
 	void __iomem *base;
@@ -112,6 +113,7 @@ struct axxia_i2c_dev {
 	struct i2c_adapter adapter;
 	struct clk *i2c_clk;
 	u32 bus_clk_rate;
+	bool last;
 };
 
 static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask)
@@ -324,15 +326,14 @@ static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
 		/* Stop completed */
 		i2c_int_disable(idev, ~MST_STATUS_TSS);
 		complete(&idev->msg_complete);
-	} else if (status & MST_STATUS_SNS) {
+	} else if (status & (MST_STATUS_SNS | MST_STATUS_SS)) {
 		/* Transfer done */
-		i2c_int_disable(idev, ~MST_STATUS_TSS);
+		int mask = idev->last ? ~0 : ~MST_STATUS_TSS;
+
+		i2c_int_disable(idev, mask);
 		if (i2c_m_rd(idev->msg_r) && idev->msg_xfrd_r < idev->msg_r->len)
 			axxia_i2c_empty_rx_fifo(idev);
 		complete(&idev->msg_complete);
-	} else if (status & MST_STATUS_SS) {
-		/* Auto/Sequence transfer done */
-		complete(&idev->msg_complete);
 	} else if (status & MST_STATUS_TSS) {
 		/* Transfer timeout */
 		idev->msg_err = -ETIMEDOUT;
@@ -405,6 +406,7 @@ static int axxia_i2c_xfer_seq(struct axxia_i2c_dev *idev, struct i2c_msg msgs[])
 	idev->msg_r = &msgs[1];
 	idev->msg_xfrd = 0;
 	idev->msg_xfrd_r = 0;
+	idev->last = true;
 	axxia_i2c_fill_tx_fifo(idev);
 
 	writel(CMD_SEQUENCE, idev->base + MST_COMMAND);
@@ -415,10 +417,6 @@ static int axxia_i2c_xfer_seq(struct axxia_i2c_dev *idev, struct i2c_msg msgs[])
 	time_left = wait_for_completion_timeout(&idev->msg_complete,
 						I2C_XFER_TIMEOUT);
 
-	i2c_int_disable(idev, int_mask);
-
-	axxia_i2c_empty_rx_fifo(idev);
-
 	if (idev->msg_err == -ENXIO) {
 		if (axxia_i2c_handle_seq_nak(idev))
 			axxia_i2c_init(idev);
@@ -438,9 +436,10 @@ static int axxia_i2c_xfer_seq(struct axxia_i2c_dev *idev, struct i2c_msg msgs[])
 	return idev->msg_err;
 }
 
-static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
+static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg,
+			      bool last)
 {
-	u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS;
+	u32 int_mask = MST_STATUS_ERR;
 	u32 rx_xfer, tx_xfer;
 	unsigned long time_left;
 	unsigned int wt_value;
@@ -449,6 +448,7 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 	idev->msg_r = msg;
 	idev->msg_xfrd = 0;
 	idev->msg_xfrd_r = 0;
+	idev->last = last;
 	reinit_completion(&idev->msg_complete);
 
 	axxia_i2c_set_addr(idev, msg);
@@ -478,8 +478,13 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 	if (idev->msg_err)
 		goto out;
 
-	/* Start manual mode */
-	writel(CMD_MANUAL, idev->base + MST_COMMAND);
+	if (!last) {
+		writel(CMD_MANUAL, idev->base + MST_COMMAND);
+		int_mask |= MST_STATUS_SNS;
+	} else {
+		writel(CMD_AUTO, idev->base + MST_COMMAND);
+		int_mask |= MST_STATUS_SS;
+	}
 
 	writel(WT_EN | wt_value, idev->base + WAIT_TIMER_CONTROL);
 
@@ -507,28 +512,6 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 	return idev->msg_err;
 }
 
-static int axxia_i2c_stop(struct axxia_i2c_dev *idev)
-{
-	u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC | MST_STATUS_TSS;
-	unsigned long time_left;
-
-	reinit_completion(&idev->msg_complete);
-
-	/* Issue stop */
-	writel(0xb, idev->base + MST_COMMAND);
-	i2c_int_enable(idev, int_mask);
-	time_left = wait_for_completion_timeout(&idev->msg_complete,
-					      I2C_STOP_TIMEOUT);
-	i2c_int_disable(idev, int_mask);
-	if (time_left == 0)
-		return -ETIMEDOUT;
-
-	if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
-		dev_warn(idev->dev, "busy after stop\n");
-
-	return 0;
-}
-
 /* This function checks if the msgs[] array contains messages compatible with
  * Sequence mode of operation. This mode assumes there will be exactly one
  * write of non-zero length followed by exactly one read of non-zero length,
@@ -558,9 +541,7 @@ axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	i2c_int_enable(idev, MST_STATUS_TSS);
 
 	for (i = 0; ret == 0 && i < num; ++i)
-		ret = axxia_i2c_xfer_msg(idev, &msgs[i]);
-
-	axxia_i2c_stop(idev);
+		ret = axxia_i2c_xfer_msg(idev, &msgs[i], i == (num - 1));
 
 	return ret ? : i;
 }

drivers/i2c/busses/i2c-brcmstb.c

@@ -165,7 +165,6 @@ static const struct bsc_clk_param bsc_clk[] = {
 struct brcmstb_i2c_dev {
 	struct device *device;
 	void __iomem *base;
-	void __iomem *irq_base;
 	int irq;
 	struct bsc_regs *bsc_regmap;
 	struct i2c_adapter adapter;

drivers/i2c/busses/i2c-designware-common.c

@@ -251,13 +251,27 @@ unsigned long i2c_dw_clk_rate(struct dw_i2c_dev *dev)
 
 int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare)
 {
+	int ret;
+
 	if (IS_ERR(dev->clk))
 		return PTR_ERR(dev->clk);
 
-	if (prepare)
-		return clk_prepare_enable(dev->clk);
+	if (prepare) {
+		/* Optional interface clock */
+		ret = clk_prepare_enable(dev->pclk);
+		if (ret)
+			return ret;
+
+		ret = clk_prepare_enable(dev->clk);
+		if (ret)
+			clk_disable_unprepare(dev->pclk);
+
+		return ret;
+	}
 
 	clk_disable_unprepare(dev->clk);
+	clk_disable_unprepare(dev->pclk);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_prepare_clk);

drivers/i2c/busses/i2c-designware-core.h

@@ -177,6 +177,7 @@
  * @base: IO registers pointer
  * @cmd_complete: tx completion indicator
  * @clk: input reference clock
+ * @pclk: clock required to access the registers
  * @slave: represent an I2C slave device
  * @cmd_err: run time hadware error code
  * @msgs: points to an array of messages currently being transferred
@@ -227,6 +228,7 @@ struct dw_i2c_dev {
 	void __iomem		*ext;
 	struct completion	cmd_complete;
 	struct clk		*clk;
+	struct clk		*pclk;
 	struct reset_control	*rst;
 	struct i2c_client		*slave;
 	u32			(*get_clk_rate_khz) (struct dw_i2c_dev *dev);

drivers/i2c/busses/i2c-designware-platdrv.c

@@ -344,6 +344,11 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	else
 		i2c_dw_configure_master(dev);
 
+	/* Optional interface clock */
+	dev->pclk = devm_clk_get_optional(&pdev->dev, "pclk");
+	if (IS_ERR(dev->pclk))
+		return PTR_ERR(dev->pclk);
+
 	dev->clk = devm_clk_get(&pdev->dev, NULL);
 	if (!i2c_dw_prepare_clk(dev, true)) {
 		u64 clk_khz;

drivers/i2c/busses/i2c-gpio.c

@@ -413,6 +413,8 @@ static int i2c_gpio_probe(struct platform_device *pdev)
 
 	if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
 		dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
+	else
+		bit_data->can_do_atomic = true;
 
 	bit_data->setsda = i2c_gpio_setsda_val;
 	bit_data->setscl = i2c_gpio_setscl_val;

drivers/i2c/busses/i2c-imx-lpi2c.c

@@ -639,8 +639,7 @@ static int lpi2c_imx_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int lpi2c_runtime_suspend(struct device *dev)
+static int __maybe_unused lpi2c_runtime_suspend(struct device *dev)
 {
 	struct lpi2c_imx_struct *lpi2c_imx = dev_get_drvdata(dev);
 
@@ -650,7 +649,7 @@ static int lpi2c_runtime_suspend(struct device *dev)
 	return 0;
 }
 
-static int lpi2c_runtime_resume(struct device *dev)
+static int __maybe_unused lpi2c_runtime_resume(struct device *dev)
 {
 	struct lpi2c_imx_struct *lpi2c_imx = dev_get_drvdata(dev);
 	int ret;
@@ -671,10 +670,6 @@ static const struct dev_pm_ops lpi2c_pm_ops = {
 	SET_RUNTIME_PM_OPS(lpi2c_runtime_suspend,
 			   lpi2c_runtime_resume, NULL)
 };
-#define IMX_LPI2C_PM      (&lpi2c_pm_ops)
-#else
-#define IMX_LPI2C_PM      NULL
-#endif
 
 static struct platform_driver lpi2c_imx_driver = {
 	.probe = lpi2c_imx_probe,
@@ -682,7 +677,7 @@ static struct platform_driver lpi2c_imx_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table = lpi2c_imx_of_match,
-		.pm = IMX_LPI2C_PM,
+		.pm = &lpi2c_pm_ops,
 	},
 };
 

drivers/i2c/busses/i2c-isch.c

@@ -30,7 +30,6 @@
 #include <linux/ioport.h>
 #include <linux/i2c.h>
 #include <linux/io.h>
-#include <linux/acpi.h>
 
 /* SCH SMBus address offsets */
 #define SMBHSTCNT	(0 + sch_smba)

drivers/i2c/busses/i2c-nomadik.c

@@ -1070,8 +1070,7 @@ static int nmk_i2c_remove(struct amba_device *adev)
 	/* disable the controller */
 	i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
 	clk_disable_unprepare(dev->clk);
-	if (res)
-		release_mem_region(res->start, resource_size(res));
+	release_mem_region(res->start, resource_size(res));
 
 	return 0;
 }

drivers/i2c/busses/i2c-ocores.c

@@ -26,8 +26,6 @@
 #include <linux/spinlock.h>
 #include <linux/jiffies.h>
 
-#define OCORES_FLAG_POLL BIT(0)
-
 /*
  * 'process_lock' exists because ocores_process() and ocores_process_timeout()
  * can't run in parallel.
@@ -37,7 +35,6 @@ struct ocores_i2c {
 	int iobase;
 	u32 reg_shift;
 	u32 reg_io_width;
-	unsigned long flags;
 	wait_queue_head_t wait;
 	struct i2c_adapter adap;
 	struct i2c_msg *msg;
@@ -403,11 +400,7 @@ static int ocores_xfer_polling(struct i2c_adapter *adap,
 static int ocores_xfer(struct i2c_adapter *adap,
 		       struct i2c_msg *msgs, int num)
 {
-	struct ocores_i2c *i2c = i2c_get_adapdata(adap);
-
-	if (i2c->flags & OCORES_FLAG_POLL)
-		return ocores_xfer_polling(adap, msgs, num);
-	return ocores_xfer_core(i2c, msgs, num, false);
+	return ocores_xfer_core(i2c_get_adapdata(adap), msgs, num, false);
 }
 
 static int ocores_init(struct device *dev, struct ocores_i2c *i2c)
@@ -447,8 +440,9 @@ static u32 ocores_func(struct i2c_adapter *adap)
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
-static const struct i2c_algorithm ocores_algorithm = {
+static struct i2c_algorithm ocores_algorithm = {
 	.master_xfer = ocores_xfer,
+	.master_xfer_atomic = ocores_xfer_polling,
 	.functionality = ocores_func,
 };
 
@@ -673,13 +667,13 @@ static int ocores_i2c_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq == -ENXIO) {
-		i2c->flags |= OCORES_FLAG_POLL;
+		ocores_algorithm.master_xfer = ocores_xfer_polling;
 	} else {
 		if (irq < 0)
 			return irq;
 	}
 
-	if (!(i2c->flags & OCORES_FLAG_POLL)) {
+	if (ocores_algorithm.master_xfer != ocores_xfer_polling) {
 		ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
 				       pdev->name, i2c);
 		if (ret) {

drivers/i2c/busses/i2c-omap.c

@@ -269,6 +269,8 @@ static const u8 reg_map_ip_v2[] = {
 	[OMAP_I2C_IP_V2_IRQENABLE_CLR] = 0x30,
 };
 
+static int omap_i2c_xfer_data(struct omap_i2c_dev *omap);
+
 static inline void omap_i2c_write_reg(struct omap_i2c_dev *omap,
 				      int reg, u16 val)
 {
@@ -648,15 +650,28 @@ static void omap_i2c_resize_fifo(struct omap_i2c_dev *omap, u8 size, bool is_rx)
 			(1000 * omap->speed / 8);
 }
 
+static void omap_i2c_wait(struct omap_i2c_dev *omap)
+{
+	u16 stat;
+	u16 mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
+	int count = 0;
+
+	do {
+		stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
+		count++;
+	} while (!(stat & mask) && count < 5);
+}
+
 /*
  * Low level master read/write transaction.
  */
 static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
-			     struct i2c_msg *msg, int stop)
+			     struct i2c_msg *msg, int stop, bool polling)
 {
 	struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
 	unsigned long timeout;
 	u16 w;
+	int ret;
 
 	dev_dbg(omap->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 		msg->addr, msg->len, msg->flags, stop);
@@ -680,7 +695,8 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
 	w |= OMAP_I2C_BUF_RXFIF_CLR | OMAP_I2C_BUF_TXFIF_CLR;
 	omap_i2c_write_reg(omap, OMAP_I2C_BUF_REG, w);
 
-	reinit_completion(&omap->cmd_complete);
+	if (!polling)
+		reinit_completion(&omap->cmd_complete);
 	omap->cmd_err = 0;
 
 	w = OMAP_I2C_CON_EN | OMAP_I2C_CON_MST | OMAP_I2C_CON_STT;
@@ -732,8 +748,18 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
 	 * REVISIT: We should abort the transfer on signals, but the bus goes
 	 * into arbitration and we're currently unable to recover from it.
 	 */
-	timeout = wait_for_completion_timeout(&omap->cmd_complete,
-						OMAP_I2C_TIMEOUT);
+	if (!polling) {
+		timeout = wait_for_completion_timeout(&omap->cmd_complete,
+						      OMAP_I2C_TIMEOUT);
+	} else {
+		do {
+			omap_i2c_wait(omap);
+			ret = omap_i2c_xfer_data(omap);
+		} while (ret == -EAGAIN);
+
+		timeout = !ret;
+	}
+
 	if (timeout == 0) {
 		dev_err(omap->dev, "controller timed out\n");
 		omap_i2c_reset(omap);
@@ -772,7 +798,8 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
  * to do the work during IRQ processing.
  */
 static int
-omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+omap_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg msgs[], int num,
+		     bool polling)
 {
 	struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
 	int i;
@@ -794,7 +821,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 		omap->set_mpu_wkup_lat(omap->dev, omap->latency);
 
 	for (i = 0; i < num; i++) {
-		r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)));
+		r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)),
+				      polling);
 		if (r != 0)
 			break;
 	}
@@ -813,6 +841,18 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	return r;
 }
 
+static int
+omap_i2c_xfer_irq(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	return omap_i2c_xfer_common(adap, msgs, num, false);
+}
+
+static int
+omap_i2c_xfer_polling(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	return omap_i2c_xfer_common(adap, msgs, num, true);
+}
+
 static u32
 omap_i2c_func(struct i2c_adapter *adap)
 {
@@ -1035,10 +1075,8 @@ omap_i2c_isr(int irq, void *dev_id)
 	return ret;
 }
 
-static irqreturn_t
-omap_i2c_isr_thread(int this_irq, void *dev_id)
+static int omap_i2c_xfer_data(struct omap_i2c_dev *omap)
 {
-	struct omap_i2c_dev *omap = dev_id;
 	u16 bits;
 	u16 stat;
 	int err = 0, count = 0;
@@ -1056,7 +1094,8 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
 
 		if (!stat) {
 			/* my work here is done */
-			goto out;
+			err = -EAGAIN;
+			break;
 		}
 
 		dev_dbg(omap->dev, "IRQ (ISR = 0x%04x)\n", stat);
@@ -1165,14 +1204,25 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
 		}
 	} while (stat);
 
-	omap_i2c_complete_cmd(omap, err);
+	return err;
+}
+
+static irqreturn_t
+omap_i2c_isr_thread(int this_irq, void *dev_id)
+{
+	int ret;
+	struct omap_i2c_dev *omap = dev_id;
+
+	ret = omap_i2c_xfer_data(omap);
+	if (ret != -EAGAIN)
+		omap_i2c_complete_cmd(omap, ret);
 
-out:
 	return IRQ_HANDLED;
 }
 
 static const struct i2c_algorithm omap_i2c_algo = {
-	.master_xfer	= omap_i2c_xfer,
+	.master_xfer	= omap_i2c_xfer_irq,
+	.master_xfer_atomic	= omap_i2c_xfer_polling,
 	.functionality	= omap_i2c_func,
 };
 

drivers/i2c/busses/i2c-piix4.c

@@ -19,6 +19,7 @@
 	Serverworks OSB4, CSB5, CSB6, HT-1000, HT-1100
 	ATI IXP200, IXP300, IXP400, SB600, SB700/SP5100, SB800
 	AMD Hudson-2, ML, CZ
+	Hygon CZ
 	SMSC Victory66
 
    Note: we assume there can only be one device, with one or more
@@ -289,7 +290,9 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
 	     PIIX4_dev->revision >= 0x41) ||
 	    (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD &&
 	     PIIX4_dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS &&
-	     PIIX4_dev->revision >= 0x49))
+	     PIIX4_dev->revision >= 0x49) ||
+	    (PIIX4_dev->vendor == PCI_VENDOR_ID_HYGON &&
+	     PIIX4_dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS))
 		smb_en = 0x00;
 	else
 		smb_en = (aux) ? 0x28 : 0x2c;
@@ -361,7 +364,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
 		 piix4_smba, i2ccfg >> 4);
 
 	/* Find which register is used for port selection */
-	if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD) {
+	if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD ||
+	    PIIX4_dev->vendor == PCI_VENDOR_ID_HYGON) {
 		switch (PIIX4_dev->device) {
 		case PCI_DEVICE_ID_AMD_KERNCZ_SMBUS:
 			piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_KERNCZ;
@@ -794,6 +798,7 @@ static const struct pci_device_id piix4_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_HUDSON2_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
 		     PCI_DEVICE_ID_SERVERWORKS_OSB4) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
@@ -904,11 +909,13 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
 	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
 	     dev->revision >= 0x40) ||
-	    dev->vendor == PCI_VENDOR_ID_AMD) {
+	    dev->vendor == PCI_VENDOR_ID_AMD ||
+	    dev->vendor == PCI_VENDOR_ID_HYGON) {
 		bool notify_imc = false;
 		is_sb800 = true;
 
-		if (dev->vendor == PCI_VENDOR_ID_AMD &&
+		if ((dev->vendor == PCI_VENDOR_ID_AMD ||
+		     dev->vendor == PCI_VENDOR_ID_HYGON) &&
 		    dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
 			u8 imc;
 

drivers/i2c/busses/i2c-rcar.c

@@ -85,6 +85,7 @@
 /* ICFBSCR */
 #define TCYC17	0x0f		/* 17*Tcyc delay 1st bit between SDA and SCL */
 
+#define RCAR_MIN_DMA_LEN	8
 
 #define RCAR_BUS_PHASE_START	(MDBS | MIE | ESG)
 #define RCAR_BUS_PHASE_DATA	(MDBS | MIE)
@@ -398,7 +399,7 @@ static void rcar_i2c_dma_callback(void *data)
 	rcar_i2c_dma_unmap(priv);
 }
 
-static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
+static bool rcar_i2c_dma(struct rcar_i2c_priv *priv)
 {
 	struct device *dev = rcar_i2c_priv_to_dev(priv);
 	struct i2c_msg *msg = priv->msg;
@@ -412,9 +413,9 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	int len;
 
 	/* Do various checks to see if DMA is feasible at all */
-	if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE) ||
-	    (read && priv->flags & ID_P_NO_RXDMA))
-		return;
+	if (IS_ERR(chan) || msg->len < RCAR_MIN_DMA_LEN ||
+	    !(msg->flags & I2C_M_DMA_SAFE) || (read && priv->flags & ID_P_NO_RXDMA))
+		return false;
 
 	if (read) {
 		/*
@@ -434,7 +435,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	dma_addr = dma_map_single(chan->device->dev, buf, len, dir);
 	if (dma_mapping_error(chan->device->dev, dma_addr)) {
 		dev_dbg(dev, "dma map failed, using PIO\n");
-		return;
+		return false;
 	}
 
 	sg_dma_len(&priv->sg) = len;
@@ -448,7 +449,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	if (!txdesc) {
 		dev_dbg(dev, "dma prep slave sg failed, using PIO\n");
 		rcar_i2c_cleanup_dma(priv);
-		return;
+		return false;
 	}
 
 	txdesc->callback = rcar_i2c_dma_callback;
@@ -458,7 +459,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	if (dma_submit_error(cookie)) {
 		dev_dbg(dev, "submitting dma failed, using PIO\n");
 		rcar_i2c_cleanup_dma(priv);
-		return;
+		return false;
 	}
 
 	/* Enable DMA Master Received/Transmitted */
@@ -468,6 +469,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 		rcar_i2c_write(priv, ICDMAER, TMDMAE);
 
 	dma_async_issue_pending(chan);
+	return true;
 }
 
 static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
@@ -478,6 +480,10 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
 	if (!(msr & MDE))
 		return;
 
+	/* Check if DMA can be enabled and take over */
+	if (priv->pos == 1 && rcar_i2c_dma(priv))
+		return;
+
 	if (priv->pos < msg->len) {
 		/*
 		 * Prepare next data to ICRXTX register.
@@ -488,13 +494,6 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
 		 */
 		rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
 		priv->pos++;
-
-		/*
-		 * Try to use DMA to transmit the rest of the data if
-		 * address transfer phase just finished.
-		 */
-		if (msr & MAT)
-			rcar_i2c_dma(priv);
 	} else {
 		/*
 		 * The last data was pushed to ICRXTX on _PREV_ empty irq.
@@ -921,6 +920,9 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 	struct i2c_timings i2c_t;
 	int irq, ret;
 
+	/* Otherwise logic will break because some bytes must always use PIO */
+	BUILD_BUG_ON_MSG(RCAR_MIN_DMA_LEN < 3, "Invalid min DMA length");
+
 	priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

drivers/i2c/busses/i2c-riic.c

@@ -43,6 +43,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 
 #define RIIC_ICCR1	0x00
 #define RIIC_ICCR2	0x04
@@ -112,12 +113,10 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 {
 	struct riic_dev *riic = i2c_get_adapdata(adap);
 	unsigned long time_left;
-	int i, ret;
+	int i;
 	u8 start_bit;
 
-	ret = clk_prepare_enable(riic->clk);
-	if (ret)
-		return ret;
+	pm_runtime_get_sync(adap->dev.parent);
 
 	if (readb(riic->base + RIIC_ICCR2) & ICCR2_BBSY) {
 		riic->err = -EBUSY;
@@ -150,7 +149,7 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	}
 
  out:
-	clk_disable_unprepare(riic->clk);
+	pm_runtime_put(adap->dev.parent);
 
 	return riic->err ?: num;
 }
@@ -281,20 +280,18 @@ static const struct i2c_algorithm riic_algo = {
 
 static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
 {
-	int ret;
+	int ret = 0;
 	unsigned long rate;
 	int total_ticks, cks, brl, brh;
 
-	ret = clk_prepare_enable(riic->clk);
-	if (ret)
-		return ret;
+	pm_runtime_get_sync(riic->adapter.dev.parent);
 
 	if (t->bus_freq_hz > 400000) {
 		dev_err(&riic->adapter.dev,
 			"unsupported bus speed (%dHz). 400000 max\n",
 			t->bus_freq_hz);
-		clk_disable_unprepare(riic->clk);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	rate = clk_get_rate(riic->clk);
@@ -332,8 +329,8 @@ static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
 	if (brl > (0x1F + 3)) {
 		dev_err(&riic->adapter.dev, "invalid speed (%lu). Too slow.\n",
 			(unsigned long)t->bus_freq_hz);
-		clk_disable_unprepare(riic->clk);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	brh = total_ticks - brl;
@@ -378,9 +375,9 @@ static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
 
 	riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
 
-	clk_disable_unprepare(riic->clk);
-
-	return 0;
+out:
+	pm_runtime_put(riic->adapter.dev.parent);
+	return ret;
 }
 
 static struct riic_irq_desc riic_irqs[] = {
@@ -439,28 +436,36 @@ static int riic_i2c_probe(struct platform_device *pdev)
 
 	i2c_parse_fw_timings(&pdev->dev, &i2c_t, true);
 
+	pm_runtime_enable(&pdev->dev);
+
 	ret = riic_init_hw(riic, &i2c_t);
 	if (ret)
-		return ret;
-
+		goto out;
 
 	ret = i2c_add_adapter(adap);
 	if (ret)
-		return ret;
+		goto out;
 
 	platform_set_drvdata(pdev, riic);
 
 	dev_info(&pdev->dev, "registered with %dHz bus speed\n",
 		 i2c_t.bus_freq_hz);
 	return 0;
+
+out:
+	pm_runtime_disable(&pdev->dev);
+	return ret;
 }
 
 static int riic_i2c_remove(struct platform_device *pdev)
 {
 	struct riic_dev *riic = platform_get_drvdata(pdev);
 
+	pm_runtime_get_sync(&pdev->dev);
 	writeb(0, riic->base + RIIC_ICIER);
+	pm_runtime_put(&pdev->dev);
 	i2c_del_adapter(&riic->adapter);
+	pm_runtime_disable(&pdev->dev);
 
 	return 0;
 }

drivers/i2c/busses/i2c-stm32f7.c

@@ -476,8 +476,12 @@ static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
 
 					list_add_tail(&v->node,
 						      &solutions);
+					break;
 				}
 			}
+
+			if (p_prev == p)
+				break;
 		}
 	}
 

drivers/i2c/busses/i2c-stu300.c

@@ -328,12 +328,6 @@ static int stu300_start_and_await_event(struct stu300_dev *dev,
 {
 	int ret;
 
-	if (unlikely(irqs_disabled())) {
-		/* TODO: implement polling for this case if need be. */
-		WARN(1, "irqs are disabled, cannot poll for event\n");
-		return -EIO;
-	}
-
 	/* Lock command issue, fill in an event we wait for */
 	spin_lock_irq(&dev->cmd_issue_lock);
 	init_completion(&dev->cmd_complete);
@@ -380,13 +374,6 @@ static int stu300_await_event(struct stu300_dev *dev,
 {
 	int ret;
 
-	if (unlikely(irqs_disabled())) {
-		/* TODO: implement polling for this case if need be. */
-		dev_err(&dev->pdev->dev, "irqs are disabled on this "
-			"system!\n");
-		return -EIO;
-	}
-
 	/* Is it already here? */
 	spin_lock_irq(&dev->cmd_issue_lock);
 	dev->cmd_err = STU300_ERROR_NONE;
@@ -846,6 +833,13 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	return num;
 }
 
+static int stu300_xfer_todo(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	/* TODO: implement polling for this case if need be. */
+	WARN(1, "%s: atomic transfers not implemented\n", dev_name(&adap->dev));
+	return -EOPNOTSUPP;
+}
+
 static u32 stu300_func(struct i2c_adapter *adap)
 {
 	/* This is the simplest thing you can think of... */
@@ -853,8 +847,9 @@ static u32 stu300_func(struct i2c_adapter *adap)
 }
 
 static const struct i2c_algorithm stu300_algo = {
-	.master_xfer	= stu300_xfer,
-	.functionality	= stu300_func,
+	.master_xfer = stu300_xfer,
+	.master_xfer_atomic = stu300_xfer_todo,
+	.functionality = stu300_func,
 };
 
 static const struct i2c_adapter_quirks stu300_quirks = {

drivers/i2c/busses/i2c-tegra-bpmp.c

@@ -207,7 +207,8 @@ static int tegra_bpmp_i2c_msg_len_check(struct i2c_msg *msgs, unsigned int num)
 
 static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
 				   struct mrq_i2c_request *request,
-				   struct mrq_i2c_response *response)
+				   struct mrq_i2c_response *response,
+				   bool atomic)
 {
 	struct tegra_bpmp_message msg;
 	int err;
@@ -222,7 +223,7 @@ static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
 	msg.rx.data = response;
 	msg.rx.size = sizeof(*response);
 
-	if (irqs_disabled())
+	if (atomic)
 		err = tegra_bpmp_transfer_atomic(i2c->bpmp, &msg);
 	else
 		err = tegra_bpmp_transfer(i2c->bpmp, &msg);
@@ -230,8 +231,9 @@ static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
 	return err;
 }
 
-static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
-			       struct i2c_msg *msgs, int num)
+static int tegra_bpmp_i2c_xfer_common(struct i2c_adapter *adapter,
+				      struct i2c_msg *msgs, int num,
+				      bool atomic)
 {
 	struct tegra_bpmp_i2c *i2c = i2c_get_adapdata(adapter);
 	struct mrq_i2c_response response;
@@ -253,7 +255,7 @@ static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
 		return err;
 	}
 
-	err = tegra_bpmp_i2c_msg_xfer(i2c, &request, &response);
+	err = tegra_bpmp_i2c_msg_xfer(i2c, &request, &response, atomic);
 	if (err < 0) {
 		dev_err(i2c->dev, "failed to transfer message: %d\n", err);
 		return err;
@@ -268,6 +270,18 @@ static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
 	return num;
 }
 
+static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
+			       struct i2c_msg *msgs, int num)
+{
+	return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, false);
+}
+
+static int tegra_bpmp_i2c_xfer_atomic(struct i2c_adapter *adapter,
+				      struct i2c_msg *msgs, int num)
+{
+	return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, true);
+}
+
 static u32 tegra_bpmp_i2c_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
@@ -276,6 +290,7 @@ static u32 tegra_bpmp_i2c_func(struct i2c_adapter *adapter)
 
 static const struct i2c_algorithm tegra_bpmp_i2c_algo = {
 	.master_xfer = tegra_bpmp_i2c_xfer,
+	.master_xfer_atomic = tegra_bpmp_i2c_xfer_atomic,
 	.functionality = tegra_bpmp_i2c_func,
 };
 

drivers/i2c/i2c-mux.c

@@ -310,12 +310,18 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 		else
 			priv->algo.master_xfer = __i2c_mux_master_xfer;
 	}
+	if (parent->algo->master_xfer_atomic)
+		priv->algo.master_xfer_atomic = priv->algo.master_xfer;
+
 	if (parent->algo->smbus_xfer) {
 		if (muxc->mux_locked)
 			priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
 		else
 			priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
 	}
+	if (parent->algo->smbus_xfer_atomic)
+		priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer;
+
 	priv->algo.functionality = i2c_mux_functionality;
 
 	/* Now fill out new adapter structure */

include/linux/i2c-algo-bit.h

@@ -33,6 +33,7 @@ struct i2c_algo_bit_data {
 				   minimum 5 us for standard-mode I2C and SMBus,
 				   maximum 50 us for SMBus */
 	int timeout;		/* in jiffies */
+	bool can_do_atomic;	/* callbacks don't sleep, we can be atomic */
 };
 
 int i2c_bit_add_bus(struct i2c_adapter *);