Re: [PATCH v2] i2c: Add generic support passing secondary devices addresses

[Wolfram Sang]

On Sun, Jan 31, 2016 at 04:33:00PM +0100, Jean-Michel Hautbois wrote:
> Some I2C devices have multiple addresses assigned, for example each address
> corresponding to a different internal register map page of the device.
> So far drivers which need support for this have handled this with a driver
> specific and non-generic implementation, e.g. passing the additional address
> via platform data.
> 
> This patch provides a new helper function called i2c_new_secondary_device()
> which is intended to provide a generic way to get the secondary address
> as well as instantiate a struct i2c_client for the secondary address.
> 
> The function expects a pointer to the primary i2c_client, a name
> for the secondary address and an optional default address. The name is used
> as a handle to specify which secondary address to get.
> 
> The default address is used as a fallback in case no secondary address
> was explicitly specified. In case no secondary address and no default
> address were specified the function returns NULL.

With "no default address" you mean the function parameter is 0? Yeah,
you get a NULL pointer from i2c_new_device then, but also a dev_err
message, or?

> For now the function only supports look-up of the secondary address
> from devicetree, but it can be extended in the future
> to for example support board files and/or ACPI.

Ccing Mika. I think it can be 1:1 converted to device_property_*
functions already giving ACPI support for free?

Thanks,

   Wolfram

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