[PATCH 1/2] dt-bindings: pinctrl: airoha: Add EN7581 pinctrl controller

[Benjamin Larsson]

On 17/08/2024 00:52, Rob Herring wrote:
>> Hi, this is by design because of the register placement in the gpio block
>> and the fact that the pwm functionality is intermixed in there also. As
>> example the following registers are all GPIOCTRL:
>>
>> <0x0 0x1fbf0200 0x0 0x4>,
>> <0x0 0x1fbf0220 0x0 0x4>,
>> <0x0 0x1fbf0260 0x0 0x4>,
>> <0x0 0x1fbf0264 0x0 0x4>,
>>
>> To simplify the driver code logic the complexity is moved to the dts because
>> of that.
> DT to OS is an ABI. Don't put the complexity there. The driver is easy
> to change.
>
> Lot's of h/w blocks are just bit soup. This is not special. If a few
> regions is helpful, then that would be fine.
>
> Rob

Hi, the pwm functionality is to blame.

The following is the logic that populates the direction registers 
(GPIOCTRL).

     for (i = 0; i < ARRAY_SIZE(pinctrl->gpiochip.dir); i++) {
         ptr = devm_platform_ioremap_resource(pdev, index++);
         if (IS_ERR(ptr))
             return dev_err_probe(dev, PTR_ERR(ptr),
                          "failed to map gpio dir regs\n");

         pinctrl->gpiochip.dir[i] = ptr;
     }


As example in between 0x1fbf0200, 0x1fbf0220 and 0x1fbf0260 we have pwm 
related registers.

The gpio block could if I count it correctly be split into 8+ regions. 
The dts list contain 18 rows related to the gpio block. So the savings 
would be ca 10 rows but a register mapping list in the driver would be 
needed instead.

Is that savings worth the addition of a register lookup table ?

MvH

Benjamin Larsson