linux-kernel - [PATCH v3] i2c: designware: platdrv: Set class based on dmi

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Date:   Thu,  2 Jul 2020 11:38:32 +0200
From:   Ricardo Ribalda <ribalda@...nel.org>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wolfram Sang <wsa@...nel.org>
Cc:     Ricardo Ribalda <ribalda@...nel.org>
Subject: [PATCH v3] i2c: designware: platdrv: Set class based on dmi

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
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@...nel.org>
---

v3: Comment by Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
  - Add Fixes tag
  - Do not user strstr for dmidecode
  Comment by Jarkko Nikula <jarkko.nikula@...ux.intel.com>
  - Use dmi_check_system()
 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..a9f2d416b7d1 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 allow_probe[] = {
+	{
+		.ident = "Qtechnology QT5222",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Qtechnology"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "QT5222")
+		}
+	},
+
+	{ }
+};
+
 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(allow_probe) ?
+					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