On 2021-12-02 02:47, Linus Walleij wrote:
Hi Felix!
Thanks for your patch!
On Mon, Nov 29, 2021 at 4:54 PM Felix Fietkau <nbd@xxxxxxxx> wrote:
From: John Crispin <john@xxxxxxxxxxx>
Airoha's GPIO controller on their ARM EN7523 SoCs consists of two banks of 32
GPIOs. Each instance in DT is for an single bank.
Signed-off-by: John Crispin <john@xxxxxxxxxxx>
Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
(...)
+config GPIO_EN7523
+ tristate "Airoha GPIO support"
+ depends on ARCH_AIROHA
+ default ARCH_AIROHA
+ select GPIO_GENERIC
Yes that looks applicable, but why isn't it used?
The few 32-bit registers look like an ideal candidate for
using the generic GPIO. Check similar drivers such as
drivers/gpio/gpio-ftgpio010.c and how it uses
bgpio_init() and the nice doc for bgpio_init() in
drivers/gpio/gpio-mmio.c.
I just looked at the datasheet and the driver code again, and I think
EN7523 is too strange for proper generic GPIO support.
For each bank there are two control registers (not consecutive), which
have 2-bit fields for every GPIO line to control direction. No idea why
2 bits per line, because only values 0 and 1 are valid, the rest are
reserved.
For lines configured as output, an extra output-enable bit also needs to
be set in a separate register before output values can be written.
The code does use bgpio to read/write values, but that's about it.
I don't think it would do the generic GPIO code any good to support this
weirdness.
- Felix
