[U-Boot] [PATCH 45/69] x86: Add an ICH6 pin configuration driver

[Bin Meng]

On Mon, Mar 7, 2016 at 10:28 AM, Simon Glass <sjg at chromium.org> wrote:
> Add a driver which sets up the pin configuration on x86 devices with an ICH6
> (or later) Platform Controller Hub.
>
> The driver is not in the pinctrl uclass due to some oddities of the way x86
> devices work:
>
> - The GPIO controller is not present in I/O space until it is set up
> - This is done by writing a register in the PCH
> - The PCH has a driver which itself uses PCI, another driver
> - The pinctrl uclass requires that a pinctrl device be available before any
> other device can be probed
>
> It would be possible to work around the limitations by:
> - Hard-coding the GPIO address rather than reading it from the PCH
> - Using special x86 PCI access to set the GPIO address in the PCH
>
> However it is not clear that this is better, since the pin configuration
> driver does not actually provide normal pin configuration services - it
> simply sets up all the pins statically when probed. While this remains the
> case, it seems better to use a syscon uclass instead. This can be probed
> whenever it is needed, without any limitations.
>
> Also add an 'invert' property to support inverting the input.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  arch/x86/include/asm/cpu.h                         |   1 +
>  arch/x86/lib/Makefile                              |   1 +
>  arch/x86/lib/pinctrl_ich6.c                        | 216 +++++++++++++++++++++
>  .../gpio/intel,x86-pinctrl.txt                     |   1 +
>  4 files changed, 219 insertions(+)
>  create mode 100644 arch/x86/lib/pinctrl_ich6.c
>

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>