Re: [PATCH v3 1/2] i2c: core: Introduce i2c_client_get_device_id helper function

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 13 Nov 2022 18:46:30 +0100
Angel Iglesias <ang.iglesiasg@gmail.com> wrote:

> 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>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 */
>  
>  /**