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

Pull i2c fixes from Wolfram Sang:
 "The usual driver fixes and documentation updates"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: mlxcpld: check correct size of maximum RECV_LEN packet
  i2c: add Kconfig help text for slave mode
  i2c: slave-eeprom: update documentation
  i2c: eg20t: Load module automatically if ID matches
  i2c: designware: platdrv: Set class based on DMI
  i2c: algo-pca: Add 0x78 as SCL stuck low status for PCA9665

Documentation/i2c/slave-eeprom-backend.rst

 ==============================
-Linux I2C slave eeprom backend
+Linux I2C slave EEPROM backend
 ==============================
 
-by Wolfram Sang <wsa@sang-engineering.com> in 2014-15
+by Wolfram Sang <wsa@sang-engineering.com> in 2014-20
 
-This is a proof-of-concept backend which acts like an EEPROM on the connected
-I2C bus. The memory contents can be modified from userspace via this file
-located in sysfs::
+This backend simulates an EEPROM on the connected I2C bus. Its memory contents
+can be accessed from userspace via this file located in sysfs::
 
 	/sys/bus/i2c/devices/<device-directory>/slave-eeprom
 
+The following types are available: 24c02, 24c32, 24c64, and 24c512. Read-only
+variants are also supported. The name needed for instantiating has the form
+'slave-<type>[ro]'. Examples follow:
+
+24c02, read/write, address 0x64:
+  # echo slave-24c02 0x1064 > /sys/bus/i2c/devices/i2c-1/new_device
+
+24c512, read-only, address 0x42:
+  # echo slave-24c512ro 0x1042 > /sys/bus/i2c/devices/i2c-1/new_device
+
+You can also preload data during boot if a device-property named
+'firmware-name' contains a valid filename (DT or ACPI only).
+
 As of 2015, Linux doesn't support poll on binary sysfs files, so there is no
 notification when another master changed the content.

drivers/i2c/Kconfig

@@ -113,11 +113,18 @@ config I2C_STUB
 
 config I2C_SLAVE
 	bool "I2C slave support"
+	help
+	  This enables Linux to act as an I2C slave device. Note that your I2C
+	  bus master driver also needs to support this functionality. Please
+	  read Documentation/i2c/slave-interface.rst for further details.
 
 if I2C_SLAVE
 
 config I2C_SLAVE_EEPROM
 	tristate "I2C eeprom slave driver"
+	help
+	  This backend makes Linux behave like an I2C EEPROM. Please read
+	  Documentation/i2c/slave-eeprom-backend.rst for further details.
 
 endif
 

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

@@ -314,7 +314,8 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
 			DEB2("BUS ERROR - SDA Stuck low\n");
 			pca_reset(adap);
 			goto out;
-		case 0x90: /* Bus error - SCL stuck low */
+		case 0x78: /* Bus error - SCL stuck low (PCA9665) */
+		case 0x90: /* Bus error - SCL stuck low (PCA9564) */
 			DEB2("BUS ERROR - SCL Stuck low\n");
 			pca_reset(adap);
 			goto out;

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

@@ -12,6 +12,7 @@
 #include <linux/clk-provider.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
@@ -191,6 +192,17 @@ static int dw_i2c_plat_request_regs(struct dw_i2c_dev *dev)
 	return ret;
 }
 
+static const struct dmi_system_id dw_i2c_hwmon_class_dmi[] = {
+	{
+		.ident = "Qtechnology QT5222",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Qtechnology"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "QT5222"),
+		},
+	},
+	{ } /* terminate list */
+};
+
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -267,7 +279,8 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 
 	adap = &dev->adapter;
 	adap->owner = THIS_MODULE;
-	adap->class = I2C_CLASS_DEPRECATED;
+	adap->class = dmi_check_system(dw_i2c_hwmon_class_dmi) ?
+					I2C_CLASS_HWMON : I2C_CLASS_DEPRECATED;
 	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
 	adap->dev.of_node = pdev->dev.of_node;
 	adap->nr = -1;

drivers/i2c/busses/i2c-eg20t.c

@@ -180,6 +180,7 @@ static const struct pci_device_id pch_pcidev_id[] = {
 	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_I2C), 1, },
 	{0,}
 };
+MODULE_DEVICE_TABLE(pci, pch_pcidev_id);
 
 static irqreturn_t pch_i2c_handler(int irq, void *pData);
 

drivers/i2c/busses/i2c-mlxcpld.c

@@ -337,9 +337,9 @@ static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv *priv)
 		if (priv->smbus_block && (val & MLXCPLD_I2C_SMBUS_BLK_BIT)) {
 			mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_NUM_DAT_REG,
 					      &datalen, 1);
-			if (unlikely(datalen > (I2C_SMBUS_BLOCK_MAX + 1))) {
+			if (unlikely(datalen > I2C_SMBUS_BLOCK_MAX)) {
 				dev_err(priv->dev, "Incorrect smbus block read message len\n");
-				return -E2BIG;
+				return -EPROTO;
 			}
 		} else {
 			datalen = priv->xfer.data_len;