On Wed, Mar 13, 2019 at 05:55:25PM +0100, Wolfram Sang wrote:
> From: Heiner Kallweit <hkallwe...@gmail.com>
> 
> i2c_new_dummy is typically called from the probe function of the
> driver for the primary i2c client. It requires calls to
> i2c_unregister_device in the error path of the probe function and
> in the remove function.
> This can be simplified by introducing a device-managed version.
> 
> Note the changed error case return value type:
> i2c_new_dummy returns NULL whilst devm_new_i2c_dummy returns an ERR_PTR.
> 
> Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
> [wsa: rename new functions to 'errptr' style and fix minor kdoc issues]
> Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>

Reviewed-by: Simon Horman <horms+rene...@verge.net.au>

> ---
>  Documentation/driver-model/devres.txt |  3 +++
>  drivers/i2c/i2c-core-base.c           | 44 
> +++++++++++++++++++++++++++++++++++
>  include/linux/i2c.h                   |  3 +++
>  3 files changed, 50 insertions(+)
> 
> diff --git a/Documentation/driver-model/devres.txt 
> b/Documentation/driver-model/devres.txt
> index b277cafce71e..e36dc8041857 100644
> --- a/Documentation/driver-model/devres.txt
> +++ b/Documentation/driver-model/devres.txt
> @@ -266,6 +266,9 @@ GPIO
>    devm_gpio_request_one()
>    devm_gpio_free()
>  
> +I2C
> +  devm_i2c_new_dummy_errptr()
> +
>  IIO
>    devm_iio_device_alloc()
>    devm_iio_device_free()
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index bbca2e8bb019..7f20c6b8857f 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -921,6 +921,50 @@ struct i2c_client *i2c_new_dummy(struct i2c_adapter 
> *adapter, u16 address)
>  }
>  EXPORT_SYMBOL_GPL(i2c_new_dummy);
>  
> +struct i2c_dummy_devres {
> +     struct i2c_client *client;
> +};
> +
> +static void devm_i2c_release_dummy(struct device *dev, void *res)
> +{
> +     struct i2c_dummy_devres *this = res;
> +
> +     i2c_unregister_device(this->client);
> +}
> +
> +/**
> + * devm_i2c_new_dummy_errptr - return a new i2c device bound to a dummy 
> driver
> + * @dev: device the managed resource is bound to
> + * @adapter: the adapter managing the device
> + * @address: seven bit address to be used
> + * Context: can sleep
> + *
> + * This is the device-managed version of @i2c_new_dummy. It returns the new 
> i2c
> + * client or an ERR_PTR in case of an error.
> + */
> +struct i2c_client *devm_i2c_new_dummy_errptr(struct device *dev,
> +                                          struct i2c_adapter *adapter,
> +                                          u16 address)
> +{
> +     struct i2c_dummy_devres *dr;
> +     struct i2c_client *client;
> +
> +     dr = devres_alloc(devm_i2c_release_dummy, sizeof(*dr), GFP_KERNEL);
> +     if (!dr)
> +             return ERR_PTR(-ENOMEM);
> +
> +     client = i2c_new_dummy_errptr(adapter, address);
> +     if (IS_ERR(client)) {
> +             devres_free(dr);
> +     } else {
> +             dr->client = client;
> +             devres_add(dev, dr);
> +     }
> +
> +     return client;
> +}
> +EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_errptr);
> +
>  /**
>   * i2c_new_secondary_device - Helper to get the instantiated secondary 
> address
>   * and create the associated device
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 383510b4f083..93075c2ad9dc 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -470,6 +470,9 @@ extern struct i2c_client *
>  i2c_new_dummy(struct i2c_adapter *adap, u16 address);
>  
>  extern struct i2c_client *
> +devm_i2c_new_dummy_errptr(struct device *dev, struct i2c_adapter *adap, u16 
> address);
> +
> +extern struct i2c_client *
>  i2c_new_secondary_device(struct i2c_client *client,
>                               const char *name,
>                               u16 default_addr);
> -- 
> 2.11.0
> 

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