[PATCH v4] i2c: designware: platdrv: Set class based on DMI

[Ricardo Ribalda]

Current AMD's zen-based APUs use this core for some of its i2c-buses.

With this patch we re-enable autodetection of hwmon-alike devices, so
lm-sensors will be able to work automatically.

It does not affect the boot-time of embedded devices, as the class is
set based on the DMI information.

DMI is probed only on Qtechnology QT5222 Industrial Camera Platform

DocLink: https://qtec.com/camera-technology-camera-platforms/
Fixes: 3eddad96c439 ("i2c: designware: reverts "i2c: designware: Add support for AMD I2C controller"")
Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxx>
---
v2: Comments by Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
  - dmi -> DMI
  - Doclink
  - CodeStyle
  (I do not know what you meant by redundant in the dmi match list ...)


 drivers/i2c/busses/i2c-designware-platdrv.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index c2efaaaac252..630e28ef2412 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/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 +192,18 @@ 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 +280,8 @@ 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;
-- 
2.27.0