[v2] wifi: ath9k: Obtain system GPIOS from descriptors

The ath9k has an odd use of system-wide GPIOs: if the chip
does not have internal GPIO capability, it will try to obtain a
GPIO line from the system GPIO controller:

  if (BIT(gpio) & ah->caps.gpio_mask)
        ath9k_hw_gpio_cfg_wmac(...);
  else if (AR_SREV_SOC(ah))
        ath9k_hw_gpio_cfg_soc(ah, gpio, out, label);

Where ath9k_hw_gpio_cfg_soc() will attempt to issue
gpio_request_one() passing the local GPIO number of the controller
(0..31) to gpio_request_one().

This is somewhat peculiar and possibly even dangerous: there is
nowadays no guarantee of the numbering of these system-wide
GPIOs, and assuming that GPIO 0..31 as used by ath9k would
correspond to GPIOs 0..31 on the system as a whole seems a bit
wild.

Register all 32 GPIOs at index 0..31 directly in the ATH79K
GPIO driver and associate with WIFI if and only if we are probing
ATH79K wifi from the AHB bus (used for SoCs).

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Changes in v2:
- Define all the descriptors directly in the ATH79K
  GPIO driver in case the driver want to request them directly.
- Link to v1: https://lore.kernel.org/r/20240131-descriptors-wireless-v1-0-e1c7c5d68746@linaro.org
---
 drivers/gpio/gpio-ath79.c           | 47 ++++++++++++++++++++++++++++++++++++-
 drivers/net/wireless/ath/ath9k/hw.c | 29 ++++++++++++-----------
 drivers/net/wireless/ath/ath9k/hw.h |  3 ++-
 3 files changed, 63 insertions(+), 16 deletions(-)


---
base-commit: 4cece764965020c22cff7665b18a012006359095
change-id: 20240122-descriptors-wireless-b8da95dcab35

Best regards,

On Tue, Apr 23, 2024 at 02:12:33PM +0200, Linus Walleij wrote:
> The ath9k has an odd use of system-wide GPIOs: if the chip
> does not have internal GPIO capability, it will try to obtain a
> GPIO line from the system GPIO controller:
> 
>   if (BIT(gpio) & ah->caps.gpio_mask)
>         ath9k_hw_gpio_cfg_wmac(...);
>   else if (AR_SREV_SOC(ah))
>         ath9k_hw_gpio_cfg_soc(ah, gpio, out, label);
> 
> Where ath9k_hw_gpio_cfg_soc() will attempt to issue
> gpio_request_one() passing the local GPIO number of the controller
> (0..31) to gpio_request_one().
> 
> This is somewhat peculiar and possibly even dangerous: there is
> nowadays no guarantee of the numbering of these system-wide
> GPIOs, and assuming that GPIO 0..31 as used by ath9k would
> correspond to GPIOs 0..31 on the system as a whole seems a bit
> wild.
> 
> Register all 32 GPIOs at index 0..31 directly in the ATH79K
> GPIO driver and associate with WIFI if and only if we are probing
> ATH79K wifi from the AHB bus (used for SoCs).

...

> +/*
> + * This registers all of the ath79k GPIOs as descriptors to be picked
> + * directly from the ATH79K wifi driver if the two are jitted together
> + * in the same SoC.
> + */
> +#define ATH79K_WIFI_DESCS 32
> +static int ath79_gpio_register_wifi_descriptors(struct device *dev,
> +						const char *label)
> +{
> +	struct gpiod_lookup_table *lookup;
> +	int i;

unsigned ?

> +	/* Create a gpiod lookup using gpiochip-local offsets + 1 for NULL */
> +        lookup = devm_kzalloc(dev,
> +			      struct_size(lookup, table, ATH79K_WIFI_DESCS + 1),
> +			      GFP_KERNEL);

> +

Besides unneeded blank line the above has a broken indentation.

> +	if (!lookup)
> +		return -ENOMEM;
> +
> +	lookup->dev_id = "ath9k";
> +
> +	for (i = 0; i < ATH79K_WIFI_DESCS; i++) {

> +		lookup->table[i] = (struct gpiod_lookup)

This is not needed as GPIO_LOOKUP_IDX() is a compound literal.

> +			GPIO_LOOKUP_IDX(label, 0, NULL, i,
> +					GPIO_ACTIVE_HIGH);

Hence:

		lookup->table[i] =
			GPIO_LOOKUP_IDX(label, 0, NULL, i, GPIO_ACTIVE_HIGH);

> +	}
> +
> +	gpiod_add_lookup_table(lookup);
> +
> +	return 0;
> +}

...

> +	/* Obtains a system specific GPIO descriptor from another GPIO controller */
> +	gpiod = devm_gpiod_get_index(ah->dev, NULL, gpio, flags);

> +

Unneeded blank line.

> +	if (IS_ERR(gpiod)) {
> +		err = PTR_ERR(gpiod);
>  		ath_err(ath9k_hw_common(ah), "request GPIO%d failed:%d\n",
>  			gpio, err);
>  		return;
>  	}

Linus Walleij <linus.walleij@linaro.org> writes:

> The ath9k has an odd use of system-wide GPIOs: if the chip
> does not have internal GPIO capability, it will try to obtain a
> GPIO line from the system GPIO controller:
>
>   if (BIT(gpio) & ah->caps.gpio_mask)
>         ath9k_hw_gpio_cfg_wmac(...);
>   else if (AR_SREV_SOC(ah))
>         ath9k_hw_gpio_cfg_soc(ah, gpio, out, label);
>
> Where ath9k_hw_gpio_cfg_soc() will attempt to issue
> gpio_request_one() passing the local GPIO number of the controller
> (0..31) to gpio_request_one().
>
> This is somewhat peculiar and possibly even dangerous: there is
> nowadays no guarantee of the numbering of these system-wide
> GPIOs, and assuming that GPIO 0..31 as used by ath9k would
> correspond to GPIOs 0..31 on the system as a whole seems a bit
> wild.
>
> Register all 32 GPIOs at index 0..31 directly in the ATH79K
> GPIO driver and associate with WIFI if and only if we are probing
> ATH79K wifi from the AHB bus (used for SoCs).
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> Changes in v2:
> - Define all the descriptors directly in the ATH79K
>   GPIO driver in case the driver want to request them directly.
> - Link to v1: https://lore.kernel.org/r/20240131-descriptors-wireless-v1-0-e1c7c5d68746@linaro.org

Linus, via which tree should this go?