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    Subject[PATCH v2 2/3] i2c: core: add device-managed version of i2c_new_dummy
    Date
    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 <hkallweit1@gmail.com>
    ---
    v2:
    - use new function _i2c_new_dummy with detailed error codes
    ---
    Documentation/driver-model/devres.txt | 3 +++
    drivers/i2c/i2c-core-base.c | 38 +++++++++++++++++++++++++++++++++++
    include/linux/i2c.h | 3 +++
    3 files changed, 44 insertions(+)

    diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
    index c180045eb..6e2bccf85 100644
    --- a/Documentation/driver-model/devres.txt
    +++ b/Documentation/driver-model/devres.txt
    @@ -259,6 +259,9 @@ GPIO
    devm_gpio_request_one()
    devm_gpio_free()

    +I2C
    + devm_i2c_new_dummy
    +
    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 3faa9b1d3..7b3cd95be 100644
    --- a/drivers/i2c/i2c-core-base.c
    +++ b/drivers/i2c/i2c-core-base.c
    @@ -840,6 +840,44 @@ struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
    }
    EXPORT_SYMBOL_GPL(i2c_new_dummy);

    +static void devm_i2c_release_dummy(struct device *dev, void *res)
    +{
    + i2c_unregister_device(*(struct i2c_client **)res);
    +}
    +
    +/**
    + * devm_i2c_new_dummy - 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.
    + * Note the changed return value type: It returns the new i2c client
    + * or an ERR_PTR in case of an error.
    + */
    +struct i2c_client *devm_i2c_new_dummy(struct device *dev,
    + struct i2c_adapter *adapter,
    + u16 address)
    +{
    + struct i2c_client *ret, **dr;
    +
    + dr = devres_alloc(devm_i2c_release_dummy, sizeof(*dr), GFP_KERNEL);
    + if (!dr)
    + return ERR_PTR(-ENOMEM);
    +
    + ret = _i2c_new_dummy(adapter, address);
    + if (IS_ERR(ret)) {
    + devres_free(dr);
    + } else {
    + *dr = ret;
    + devres_add(dev, dr);
    + }
    +
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(devm_i2c_new_dummy);
    +
    /**
    * 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 5d7f3c185..aca6ebbb8 100644
    --- a/include/linux/i2c.h
    +++ b/include/linux/i2c.h
    @@ -441,6 +441,9 @@ extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
    extern struct i2c_client *
    i2c_new_dummy(struct i2c_adapter *adap, u16 address);

    +extern struct i2c_client *
    +devm_i2c_new_dummy(struct device *dev, struct i2c_adapter *adap, u16 address);
    +
    extern struct i2c_client *
    i2c_new_secondary_device(struct i2c_client *client,
    const char *name,
    --
    2.15.1

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