HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings

The low-pin-count (LPC) interface of Hip06/Hip07 accesses I/O port space of
peripherals.

Implement the LPC host controller driver which performs the I/O operations
on the underlying hardware.  We don't want to touch existing drivers such
as ipmi-bt, so this driver applies the indirect-IO introduced in the
previous patch after registering an indirect-IO node to the indirect-IO
devices list which will be searched by the I/O accessors to retrieve the
host-local I/O port.

The driver config is set as a bool instead of a tristate.  The reason here
is that, by the very nature of the driver providing a logical PIO range, it
does not make sense to have this driver as a loadable module.  Another more
specific reason is that the Huawei D03 board which includes Hip06 SoC
requires the LPC bus for UART console, so should be built in.
Tested-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Zou Rongrong <zourongrong@huawei.com>
Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>	# dts part

Documentation/devicetree/bindings/arm/hisilicon/hisilicon-low-pin-count.txt

+Hisilicon Hip06 Low Pin Count device
+  Hisilicon Hip06 SoCs implement a Low Pin Count (LPC) controller, which
+  provides I/O access to some legacy ISA devices.
+  Hip06 is based on arm64 architecture where there is no I/O space. So, the
+  I/O ports here are not CPU addresses, and there is no 'ranges' property in
+  LPC device node.
+
+Required properties:
+- compatible:  value should be as follows:
+	(a) "hisilicon,hip06-lpc"
+	(b) "hisilicon,hip07-lpc"
+- #address-cells: must be 2 which stick to the ISA/EISA binding doc.
+- #size-cells: must be 1 which stick to the ISA/EISA binding doc.
+- reg: base memory range where the LPC register set is mapped.
+
+Note:
+  The node name before '@' must be "isa" to represent the binding stick to the
+  ISA/EISA binding specification.
+
+Example:
+
+isa@a01b0000 {
+	compatible = "hisilicon,hip06-lpc";
+	#address-cells = <2>;
+	#size-cells = <1>;
+	reg = <0x0 0xa01b0000 0x0 0x1000>;
+
+	ipmi0: bt@e4 {
+		compatible = "ipmi-bt";
+		device_type = "ipmi";
+		reg = <0x01 0xe4 0x04>;
+	};
+};

drivers/bus/Kconfig

@@ -65,6 +65,14 @@ config BRCMSTB_GISB_ARB
 	  arbiter. This driver provides timeout and target abort error handling
 	  and internal bus master decoding.
 
+config HISILICON_LPC
+	bool "Support for ISA I/O space on HiSilicon Hip06/7"
+	depends on ARM64 && (ARCH_HISI || COMPILE_TEST)
+	select INDIRECT_PIO
+	help
+	  Driver to enable I/O access to devices attached to the Low Pin
+	  Count bus on the HiSilicon Hip06/7 SoC.
+
 config IMX_WEIM
 	bool "Freescale EIM DRIVER"
 	depends on ARCH_MXC

drivers/bus/Makefile

@@ -7,6 +7,7 @@
 obj-$(CONFIG_ARM_CCI)		+= arm-cci.o
 obj-$(CONFIG_ARM_CCN)		+= arm-ccn.o
 
+obj-$(CONFIG_HISILICON_LPC)	+= hisi_lpc.o
 obj-$(CONFIG_BRCMSTB_GISB_ARB)	+= brcmstb_gisb.o
 obj-$(CONFIG_IMX_WEIM)		+= imx-weim.o
 obj-$(CONFIG_MIPS_CDMM)		+= mips_cdmm.o

drivers/bus/hisi_lpc.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 Hisilicon Limited, All Rights Reserved.
+ * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
+ * Author: Zou Rongrong <zourongrong@huawei.com>
+ * Author: John Garry <john.garry@huawei.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/logic_pio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+
+#define DRV_NAME "hisi-lpc"
+
+/*
+ * Setting this bit means each IO operation will target a different port
+ * address; 0 means repeated IO operations will use the same port,
+ * such as BT.
+ */
+#define FG_INCRADDR_LPC		0x02
+
+struct lpc_cycle_para {
+	unsigned int opflags;
+	unsigned int csize; /* data length of each operation */
+};
+
+struct hisi_lpc_dev {
+	spinlock_t cycle_lock;
+	void __iomem  *membase;
+	struct logic_pio_hwaddr *io_host;
+};
+
+/* The max IO cycle counts supported is four per operation at maximum */
+#define LPC_MAX_DWIDTH	4
+
+#define LPC_REG_STARTUP_SIGNAL		0x00
+#define LPC_REG_STARTUP_SIGNAL_START	BIT(0)
+#define LPC_REG_OP_STATUS		0x04
+#define LPC_REG_OP_STATUS_IDLE		BIT(0)
+#define LPC_REG_OP_STATUS_FINISHED	BIT(1)
+#define LPC_REG_OP_LEN			0x10 /* LPC cycles count per start */
+#define LPC_REG_CMD			0x14
+#define LPC_REG_CMD_OP			BIT(0) /* 0: read, 1: write */
+#define LPC_REG_CMD_SAMEADDR		BIT(3)
+#define LPC_REG_ADDR			0x20 /* target address */
+#define LPC_REG_WDATA			0x24 /* write FIFO */
+#define LPC_REG_RDATA			0x28 /* read FIFO */
+
+/* The minimal nanosecond interval for each query on LPC cycle status */
+#define LPC_NSEC_PERWAIT	100
+
+/*
+ * The maximum waiting time is about 128us.  It is specific for stream I/O,
+ * such as ins.
+ *
+ * The fastest IO cycle time is about 390ns, but the worst case will wait
+ * for extra 256 lpc clocks, so (256 + 13) * 30ns = 8 us. The maximum burst
+ * cycles is 16. So, the maximum waiting time is about 128us under worst
+ * case.
+ *
+ * Choose 1300 as the maximum.
+ */
+#define LPC_MAX_WAITCNT		1300
+
+/* About 10us. This is specific for single IO operations, such as inb */
+#define LPC_PEROP_WAITCNT	100
+
+static int wait_lpc_idle(unsigned char *mbase, unsigned int waitcnt)
+{
+	u32 status;
+
+	do {
+		status = readl(mbase + LPC_REG_OP_STATUS);
+		if (status & LPC_REG_OP_STATUS_IDLE)
+			return (status & LPC_REG_OP_STATUS_FINISHED) ? 0 : -EIO;
+		ndelay(LPC_NSEC_PERWAIT);
+	} while (--waitcnt);
+
+	return -ETIME;
+}
+
+/*
+ * hisi_lpc_target_in - trigger a series of LPC cycles for read operation
+ * @lpcdev: pointer to hisi lpc device
+ * @para: some parameters used to control the lpc I/O operations
+ * @addr: the lpc I/O target port address
+ * @buf: where the read back data is stored
+ * @opcnt: how many I/O operations required, i.e. data width
+ *
+ * Returns 0 on success, non-zero on fail.
+ */
+static int hisi_lpc_target_in(struct hisi_lpc_dev *lpcdev,
+			      struct lpc_cycle_para *para, unsigned long addr,
+			      unsigned char *buf, unsigned long opcnt)
+{
+	unsigned int cmd_word;
+	unsigned int waitcnt;
+	unsigned long flags;
+	int ret;
+
+	if (!buf || !opcnt || !para || !para->csize || !lpcdev)
+		return -EINVAL;
+
+	cmd_word = 0; /* IO mode, Read */
+	waitcnt = LPC_PEROP_WAITCNT;
+	if (!(para->opflags & FG_INCRADDR_LPC)) {
+		cmd_word |= LPC_REG_CMD_SAMEADDR;
+		waitcnt = LPC_MAX_WAITCNT;
+	}
+
+	/* whole operation must be atomic */
+	spin_lock_irqsave(&lpcdev->cycle_lock, flags);
+
+	writel_relaxed(opcnt, lpcdev->membase + LPC_REG_OP_LEN);
+	writel_relaxed(cmd_word, lpcdev->membase + LPC_REG_CMD);
+	writel_relaxed(addr, lpcdev->membase + LPC_REG_ADDR);
+
+	writel(LPC_REG_STARTUP_SIGNAL_START,
+	       lpcdev->membase + LPC_REG_STARTUP_SIGNAL);
+
+	/* whether the operation is finished */
+	ret = wait_lpc_idle(lpcdev->membase, waitcnt);
+	if (ret) {
+		spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
+		return ret;
+	}
+
+	readsb(lpcdev->membase + LPC_REG_RDATA, buf, opcnt);
+
+	spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
+
+	return 0;
+}
+
+/*
+ * hisi_lpc_target_out - trigger a series of LPC cycles for write operation
+ * @lpcdev: pointer to hisi lpc device
+ * @para: some parameters used to control the lpc I/O operations
+ * @addr: the lpc I/O target port address
+ * @buf: where the data to be written is stored
+ * @opcnt: how many I/O operations required, i.e. data width
+ *
+ * Returns 0 on success, non-zero on fail.
+ */
+static int hisi_lpc_target_out(struct hisi_lpc_dev *lpcdev,
+			       struct lpc_cycle_para *para, unsigned long addr,
+			       const unsigned char *buf, unsigned long opcnt)
+{
+	unsigned int waitcnt;
+	unsigned long flags;
+	u32 cmd_word;
+	int ret;
+
+	if (!buf || !opcnt || !para || !lpcdev)
+		return -EINVAL;
+
+	/* default is increasing address */
+	cmd_word = LPC_REG_CMD_OP; /* IO mode, write */
+	waitcnt = LPC_PEROP_WAITCNT;
+	if (!(para->opflags & FG_INCRADDR_LPC)) {
+		cmd_word |= LPC_REG_CMD_SAMEADDR;
+		waitcnt = LPC_MAX_WAITCNT;
+	}
+
+	spin_lock_irqsave(&lpcdev->cycle_lock, flags);
+
+	writel_relaxed(opcnt, lpcdev->membase + LPC_REG_OP_LEN);
+	writel_relaxed(cmd_word, lpcdev->membase + LPC_REG_CMD);
+	writel_relaxed(addr, lpcdev->membase + LPC_REG_ADDR);
+
+	writesb(lpcdev->membase + LPC_REG_WDATA, buf, opcnt);
+
+	writel(LPC_REG_STARTUP_SIGNAL_START,
+	       lpcdev->membase + LPC_REG_STARTUP_SIGNAL);
+
+	/* whether the operation is finished */
+	ret = wait_lpc_idle(lpcdev->membase, waitcnt);
+
+	spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
+
+	return ret;
+}
+
+static unsigned long hisi_lpc_pio_to_addr(struct hisi_lpc_dev *lpcdev,
+					  unsigned long pio)
+{
+	return pio - lpcdev->io_host->io_start + lpcdev->io_host->hw_start;
+}
+
+/*
+ * hisi_lpc_comm_in - input the data in a single operation
+ * @hostdata: pointer to the device information relevant to LPC controller
+ * @pio: the target I/O port address
+ * @dwidth: the data length required to read from the target I/O port
+ *
+ * When success, data is returned. Otherwise, ~0 is returned.
+ */
+static u32 hisi_lpc_comm_in(void *hostdata, unsigned long pio, size_t dwidth)
+{
+	struct hisi_lpc_dev *lpcdev = hostdata;
+	struct lpc_cycle_para iopara;
+	unsigned long addr;
+	u32 rd_data = 0;
+	int ret;
+
+	if (!lpcdev || !dwidth || dwidth > LPC_MAX_DWIDTH)
+		return ~0;
+
+	addr = hisi_lpc_pio_to_addr(lpcdev, pio);
+
+	iopara.opflags = FG_INCRADDR_LPC;
+	iopara.csize = dwidth;
+
+	ret = hisi_lpc_target_in(lpcdev, &iopara, addr,
+				 (unsigned char *)&rd_data, dwidth);
+	if (ret)
+		return ~0;
+
+	return le32_to_cpu(rd_data);
+}
+
+/*
+ * hisi_lpc_comm_out - output the data in a single operation
+ * @hostdata: pointer to the device information relevant to LPC controller
+ * @pio: the target I/O port address
+ * @val: a value to be output from caller, maximum is four bytes
+ * @dwidth: the data width required writing to the target I/O port
+ *
+ * This function corresponds to out(b,w,l) only.
+ */
+static void hisi_lpc_comm_out(void *hostdata, unsigned long pio,
+			      u32 val, size_t dwidth)
+{
+	struct hisi_lpc_dev *lpcdev = hostdata;
+	struct lpc_cycle_para iopara;
+	const unsigned char *buf;
+	unsigned long addr;
+
+	if (!lpcdev || !dwidth || dwidth > LPC_MAX_DWIDTH)
+		return;
+
+	val = cpu_to_le32(val);
+
+	buf = (const unsigned char *)&val;
+	addr = hisi_lpc_pio_to_addr(lpcdev, pio);
+
+	iopara.opflags = FG_INCRADDR_LPC;
+	iopara.csize = dwidth;
+
+	hisi_lpc_target_out(lpcdev, &iopara, addr, buf, dwidth);
+}
+
+/*
+ * hisi_lpc_comm_ins - input the data in the buffer in multiple operations
+ * @hostdata: pointer to the device information relevant to LPC controller
+ * @pio: the target I/O port address
+ * @buffer: a buffer where read/input data bytes are stored
+ * @dwidth: the data width required writing to the target I/O port
+ * @count: how many data units whose length is dwidth will be read
+ *
+ * When success, the data read back is stored in buffer pointed by buffer.
+ * Returns 0 on success, -errno otherwise.
+ */
+static u32 hisi_lpc_comm_ins(void *hostdata, unsigned long pio, void *buffer,
+			     size_t dwidth, unsigned int count)
+{
+	struct hisi_lpc_dev *lpcdev = hostdata;
+	unsigned char *buf = buffer;
+	struct lpc_cycle_para iopara;
+	unsigned long addr;
+
+	if (!lpcdev || !buf || !count || !dwidth || dwidth > LPC_MAX_DWIDTH)
+		return -EINVAL;
+
+	iopara.opflags = 0;
+	if (dwidth > 1)
+		iopara.opflags |= FG_INCRADDR_LPC;
+	iopara.csize = dwidth;
+
+	addr = hisi_lpc_pio_to_addr(lpcdev, pio);
+
+	do {
+		int ret;
+
+		ret = hisi_lpc_target_in(lpcdev, &iopara, addr, buf, dwidth);
+		if (ret)
+			return ret;
+		buf += dwidth;
+	} while (--count);
+
+	return 0;
+}
+
+/*
+ * hisi_lpc_comm_outs - output the data in the buffer in multiple operations
+ * @hostdata: pointer to the device information relevant to LPC controller
+ * @pio: the target I/O port address
+ * @buffer: a buffer where write/output data bytes are stored
+ * @dwidth: the data width required writing to the target I/O port
+ * @count: how many data units whose length is dwidth will be written
+ */
+static void hisi_lpc_comm_outs(void *hostdata, unsigned long pio,
+			       const void *buffer, size_t dwidth,
+			       unsigned int count)
+{
+	struct hisi_lpc_dev *lpcdev = hostdata;
+	struct lpc_cycle_para iopara;
+	const unsigned char *buf = buffer;
+	unsigned long addr;
+
+	if (!lpcdev || !buf || !count || !dwidth || dwidth > LPC_MAX_DWIDTH)
+		return;
+
+	iopara.opflags = 0;
+	if (dwidth > 1)
+		iopara.opflags |= FG_INCRADDR_LPC;
+	iopara.csize = dwidth;
+
+	addr = hisi_lpc_pio_to_addr(lpcdev, pio);
+	do {
+		if (hisi_lpc_target_out(lpcdev, &iopara, addr, buf, dwidth))
+			break;
+		buf += dwidth;
+	} while (--count);
+}
+
+static const struct logic_pio_host_ops hisi_lpc_ops = {
+	.in = hisi_lpc_comm_in,
+	.out = hisi_lpc_comm_out,
+	.ins = hisi_lpc_comm_ins,
+	.outs = hisi_lpc_comm_outs,
+};
+
+/*
+ * hisi_lpc_probe - the probe callback function for hisi lpc host,
+ *		   will finish all the initialization.
+ * @pdev: the platform device corresponding to hisi lpc host
+ *
+ * Returns 0 on success, non-zero on fail.
+ */
+static int hisi_lpc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct acpi_device *acpi_device = ACPI_COMPANION(dev);
+	struct logic_pio_hwaddr *range;
+	struct hisi_lpc_dev *lpcdev;
+	resource_size_t io_end;
+	struct resource *res;
+	int ret;
+
+	lpcdev = devm_kzalloc(dev, sizeof(*lpcdev), GFP_KERNEL);
+	if (!lpcdev)
+		return -ENOMEM;
+
+	spin_lock_init(&lpcdev->cycle_lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	lpcdev->membase = devm_ioremap_resource(dev, res);
+	if (IS_ERR(lpcdev->membase))
+		return PTR_ERR(lpcdev->membase);
+
+	range = devm_kzalloc(dev, sizeof(*range), GFP_KERNEL);
+	if (!range)
+		return -ENOMEM;
+
+	range->fwnode = dev->fwnode;
+	range->flags = LOGIC_PIO_INDIRECT;
+	range->size = PIO_INDIRECT_SIZE;
+
+	ret = logic_pio_register_range(range);
+	if (ret) {
+		dev_err(dev, "register IO range failed (%d)!\n", ret);
+		return ret;
+	}
+	lpcdev->io_host = range;
+
+	/* register the LPC host PIO resources */
+	if (!acpi_device) {
+		ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
+		if (ret)
+			return ret;
+	}
+
+	lpcdev->io_host->hostdata = lpcdev;
+	lpcdev->io_host->ops = &hisi_lpc_ops;
+
+	io_end = lpcdev->io_host->io_start + lpcdev->io_host->size;
+	dev_info(dev, "registered range [%pa - %pa]\n",
+		 &lpcdev->io_host->io_start, &io_end);
+
+	return ret;
+}
+
+static const struct of_device_id hisi_lpc_of_match[] = {
+	{ .compatible = "hisilicon,hip06-lpc", },
+	{ .compatible = "hisilicon,hip07-lpc", },
+	{}
+};
+
+static struct platform_driver hisi_lpc_driver = {
+	.driver = {
+		.name           = DRV_NAME,
+		.of_match_table = hisi_lpc_of_match,
+	},
+	.probe = hisi_lpc_probe,
+};
+builtin_platform_driver(hisi_lpc_driver);