[U-Boot] [PATCH v2 2/6] dm: core: Allow multiple drivers to bind for a single node

[Dr. Philipp Tomsich]

Hi Simon,

> On 03 Mar 2017, at 05:52, Simon Glass <sjg at chromium.org> wrote:
> 
> Hi Philipp,
> 
> On 22 February 2017 at 13:47, Philipp Tomsich
> <philipp.tomsich at theobroma-systems.com <mailto:philipp.tomsich at theobroma-systems.com>> wrote:
>> Currently, driver binding stops once it encounters the first
>> compatible driver that doesn't refuse to bind. However, there are
>> cases where a single node will need to be handled by multiple driver
>> classes. For those cases we provide a configurable option to continue
>> to bind after the first driver has been found.
>> 
>> The first use cases for this are from the DM conversion of the sunxi
>> (Allwinner) architecture:
>> * pinctrl (UCLASS_PINCTRL) and gpio (UCLASS_GPIO) drivers need to
>>   bind against a single node
>> * clock (UCLASS_CLK) and reset (UCLASS_RESET) drivers also need to
>>   bind against a single node
> 
> Does linux work this way? Another approach would be to have a separate
> MISC driver with two children, one pinctrl, one clk.

The linux CLK driver creates and registers a reset-controller; the PINCTRL driver
does the same with the gpio-controller. Similar code to do this is easily possible in
U-Boot … see sunxi_pctrl_bind_gpio(…) in [PATCH v2 1/6] of this series.

However, binding multiple times makes for much simpler code and allows to keep
driver data in separate drivers.

Regards,
Philipp.