[U-Boot] [PATCH 14/23] gpio: Provide dummy get/request & is_valid functions

[Paul Burton]

On Monday, 26 September 2016 18:35:25 BST Simon Glass wrote:
> Hi Paul,
> 
> On 26 September 2016 at 12:29, Paul Burton <paul.burton at imgtec.com> wrote:
> > Allow for drivers to make use of driver model GPIOs when they're enabled
> > & available without needing to #ifdef on CONFIG_DM_GPIO by providing
> > dummy functions covering GPIO requests. Each will simply return -ENODEV
> > or -EINVAL, depending upon which the real implementation returns when a
> > GPIO isn't found. Only the driver model versions of the GPIO request
> > functions are covered & dm_gpio_request is excluded since it's
> > documented as only being of use for debugging, so drivers shouldn't be
> > calling it anyway.
> > 
> > Also provide a dummy dm_gpio_is_valid, with the idea that all other GPIO
> > functions called would be within an if (dm_gpio_is_valid(...)) statement
> > and have been optimised out in cases where that returns a compile-time
> > constant false.
> > 
> > This parallels the clock API, keeping the #ifdefs & checks in a single
> > location allowing drivers or other code to use GPIOs without needing to
> > perform such checks themselves.
> > 
> > Signed-off-by: Paul Burton <paul.burton at imgtec.com>
> > 
> > ---
> > 
> >  include/asm-generic/gpio.h | 38 ++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 38 insertions(+)
> 
> Ick - why not just define DM_GPIO? I don't think we want to provide
> special support for legacy things. It is just confusing.
> 
> - Simon

Hi Simon,

For the MIPS Boston system I already enable DM_GPIO, I went with this approach so that it 
wouldn't necessarily need to be enabled for the Crown Bay x86 system which is the other 
user of the pch_gbe driver.

Would having pch_gbe depend on CONFIG_DM_GPIO be ok with you Bin? I see 
crownbay_defconfig enables CONFIG_CMD_GPIO but couldn't find any GPIO-using code at 
a glance. So hopefully it would just work without needing to change any existing crownbay 
code?

Thanks,
    Paul
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