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From:   Angel Iglesias <ang.iglesiasg@gmail.com>
To:     linux-iio@vger.kernel.org
Cc:     =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>, linux-kernel@vger.kernel.org,
        Angel Iglesias <ang.iglesiasg@gmail.com>,
        =?UTF-8?q?Nuno=20S=C3=A1?= <noname.nuno@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Wolfram Sang <wsa@kernel.org>, linux-i2c@vger.kernel.org
Subject: [PATCH v3 1/2] i2c: core: Introduce i2c_client_get_device_id helper function
Date:   Sun, 13 Nov 2022 18:46:30 +0100
Message-Id: <a844cc7c85898b40abbdcb1f068338619c6010eb.1668361368.git.ang.iglesiasg@gmail.com>
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Introduces new helper function to aid in .probe_new() refactors. In order
to use existing i2c_get_device_id() on the probe callback, the device
match table needs to be accessible in that function, which would require
bigger refactors in some drivers using the deprecated .probe callback.

This issue was discussed in more detail in the IIO mailing list.

Link: https://lore.kernel.org/all/20221023132302.911644-11-u.kleine-koenig@pengutronix.de/
Suggested-by: Nuno Sá <noname.nuno@gmail.com>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Angel Iglesias <ang.iglesiasg@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index b4edf10e8fd0..9aa7b9d9a485 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2236,6 +2236,20 @@ int i2c_get_device_id(const struct i2c_client *client,
 }
 EXPORT_SYMBOL_GPL(i2c_get_device_id);
 
+/**
+ * i2c_client_get_device_id - get the driver match table entry of a device
+ * @client: the device to query. The device must be bound to a driver
+ *
+ * Returns a pointer to the matching entry if found, NULL otherwise.
+ */
+const struct i2c_device_id *i2c_client_get_device_id(const struct i2c_client *client)
+{
+	const struct i2c_driver *drv = to_i2c_driver(client->dev.driver);
+
+	return i2c_match_id(drv->id_table, client);
+}
+EXPORT_SYMBOL_GPL(i2c_client_get_device_id);
+
 /* ----------------------------------------------------
  * the i2c address scanning function
  * Will not work for 10-bit addresses!
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index f7c49bbdb8a1..d84e0e99f084 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -189,6 +189,7 @@ s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
 					      u8 *values);
 int i2c_get_device_id(const struct i2c_client *client,
 		      struct i2c_device_identity *id);
+const struct i2c_device_id *i2c_client_get_device_id(const struct i2c_client *client);
 #endif /* I2C */
 
 /**
-- 
2.38.1