[v2,1/3] i2c: core: improve return value handling of i2c_new_device and i2c_new_dummy

Currently i2c_new_device and i2c_new_dummy return just NULL in error
case although they have more error details internally. Therefore move
the functionality into new functions returning detailed errors and
add wrappers for compatibilty with the current API.

This allows to use these functions with detailed error codes within
the i2c core or for API extensions.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/i2c-core-base.c | 46 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 13 deletions(-)

2017-12-06 22:13 GMT+01:00 Heiner Kallweit <hkallweit1@gmail.com>:
> Currently i2c_new_device and i2c_new_dummy return just NULL in error
> case although they have more error details internally. Therefore move
> the functionality into new functions returning detailed errors and
> add wrappers for compatibilty with the current API.
>
> This allows to use these functions with detailed error codes within
> the i2c core or for API extensions.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
>  drivers/i2c/i2c-core-base.c | 46 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 33 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index bb34a5d41..3faa9b1d3 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -656,7 +656,7 @@ static int i2c_dev_irq_from_resources(const struct resource *resources,
>  }
>
>  /**
> - * i2c_new_device - instantiate an i2c device
> + * _i2c_new_device - instantiate an i2c device
>   * @adap: the adapter managing the device
>   * @info: describes one I2C device; bus_num is ignored
>   * Context: can sleep
> @@ -669,17 +669,17 @@ static int i2c_dev_irq_from_resources(const struct resource *resources,
>   * before any i2c_adapter could exist.
>   *
>   * This returns the new i2c client, which may be saved for later use with
> - * i2c_unregister_device(); or NULL to indicate an error.
> + * i2c_unregister_device(); or an ERR_PTR to indicate an error.
>   */
> -struct i2c_client *
> -i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> +static struct i2c_client *
> +_i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
>  {
>         struct i2c_client       *client;
>         int                     status;
>
>         client = kzalloc(sizeof *client, GFP_KERNEL);
>         if (!client)
> -               return NULL;
> +               return ERR_PTR(-ENOMEM);
>
>         client->adapter = adap;
>
> @@ -746,7 +746,17 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
>                 client->name, client->addr, status);
>  out_err_silent:
>         kfree(client);
> -       return NULL;
> +       return ERR_PTR(status);
> +}
> +
> +/* wrapper to be compatible with the current API */
> +struct i2c_client *
> +i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> +{
> +       struct i2c_client *ret;
> +
> +       ret = _i2c_new_device(adap, info);
> +       return IS_ERR(ret) ? NULL : ret;
>  }
>  EXPORT_SYMBOL_GPL(i2c_new_device);
>
> @@ -793,7 +803,7 @@ static struct i2c_driver dummy_driver = {
>  };
>
>  /**
> - * i2c_new_dummy - return a new i2c device bound to a dummy driver
> + * _i2c_new_dummy - return a new i2c device bound to a dummy driver
>   * @adapter: the adapter managing the device
>   * @address: seven bit address to be used
>   * Context: can sleep
> @@ -808,15 +818,25 @@ static struct i2c_driver dummy_driver = {
>   * different driver.
>   *
>   * This returns the new i2c client, which should be saved for later use with
> - * i2c_unregister_device(); or NULL to indicate an error.
> + * i2c_unregister_device(); or an ERR_PTR to indicate an error.
>   */
> -struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
> +static struct i2c_client *
> +_i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
>  {
>         struct i2c_board_info info = {
>                 I2C_BOARD_INFO("dummy", address),
>         };
>
> -       return i2c_new_device(adapter, &info);
> +       return _i2c_new_device(adapter, &info);
> +}
> +
> +/* wrapper to be compatible with the current API */
> +struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
> +{
> +       struct i2c_client *ret;
> +
> +       ret = _i2c_new_dummy(adapter, address);
> +       return IS_ERR(ret) ? NULL : ret;
>  }
>  EXPORT_SYMBOL_GPL(i2c_new_dummy);
>
> @@ -939,9 +959,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
>                 info.flags |= I2C_CLIENT_SLAVE;
>         }
>
> -       client = i2c_new_device(adap, &info);
> -       if (!client)
> -               return -EINVAL;
> +       client = _i2c_new_device(adap, &info);
> +       if (IS_ERR(client))
> +               return PTR_ERR(client);
>
>         /* Keep track of the added device */
>         mutex_lock(&adap->userspace_clients_lock);
> --
> 2.15.1
>
>

Looks good to me in general. I would just rename _i2c_new_device to
__i2c_new_device (with two leading underscores) as it seems to be a
consistent pattern for this kind of private functions in i2c core.

Thanks,
Bartosz