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From: egyszeregy@freemail.hu
To: wsa+renesas@sang-engineering.com,
	linux-i2c@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: =?UTF-8?q?Benjamin=20Sz=C5=91ke?= <egyszeregy@freemail.hu>
Subject: [PATCH] i2c-dev: Introduce "linux,i2c-dev-name" property for device tree of I2C controller.
Date: Sun, 19 May 2024 18:55:04 +0200
Message-Id: <20240519165504.19627-1-egyszeregy@freemail.hu>
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From: Benjamin Szőke <egyszeregy@freemail.hu>

Optionally, an I2C controller may have a "linux,i2c-dev-name" property.
This is a string which is defining a custom suffix name for I2C device
in /dev/i2c-<name> format. It helps to improve software portability between
various SoCs and reduce complexities of hardware related codes in SWs.

Signed-off-by: Benjamin Szőke <egyszeregy@freemail.hu>
---
 drivers/i2c/i2c-dev.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 8b7e599f1674..df4cec88ea59 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -651,6 +651,7 @@ static void i2cdev_dev_release(struct device *dev)
 
 static int i2cdev_attach_adapter(struct device *dev)
 {
+	const char *name;
 	struct i2c_adapter *adap;
 	struct i2c_dev *i2c_dev;
 	int res;
@@ -672,7 +673,16 @@ static int i2cdev_attach_adapter(struct device *dev)
 	i2c_dev->dev.parent = &adap->dev;
 	i2c_dev->dev.release = i2cdev_dev_release;
 
-	res = dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
+	/*
+	 * If "linux,i2c-dev-name" is specified in device tree, use /dev/i2c-<name>
+	 * in Linux userspace, otherwise use /dev/i2c-<nr>.
+	 */
+	res = device_property_read_string(&adap->dev, "linux,i2c-dev-name", &name);
+	if (res < 0)
+		res = dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
+	else
+		res = dev_set_name(&i2c_dev->dev, "i2c-%s", name);
+
 	if (res)
 		goto err_put_i2c_dev;
 
-- 
2.39.3