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

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
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@xxxxxxxxxx
---
 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(-)

diff --git a/drivers/gpio/gpio-ath79.c b/drivers/gpio/gpio-ath79.c
index f0c0c0f77eb0..f83ce0595ea8 100644
--- a/drivers/gpio/gpio-ath79.c
+++ b/drivers/gpio/gpio-ath79.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h> /* For WLAN GPIOs */
 #include <linux/platform_device.h>
 #include <linux/platform_data/gpio-ath79.h>
 #include <linux/of.h>
@@ -222,6 +223,46 @@ static const struct of_device_id ath79_gpio_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, ath79_gpio_of_match);
 
+#if IS_ENABLED(CONFIG_ATH9K_AHB)
+/*
+ * 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;
+
+	/* 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);
+
+	if (!lookup)
+		return -ENOMEM;
+
+	lookup->dev_id = "ath9k";
+
+	for (i = 0; i < ATH79K_WIFI_DESCS; i++) {
+		lookup->table[i] = (struct gpiod_lookup)
+			GPIO_LOOKUP_IDX(label, 0, NULL, i,
+					GPIO_ACTIVE_HIGH);
+	}
+
+	gpiod_add_lookup_table(lookup);
+
+	return 0;
+}
+#else
+static int ath79_gpio_register_wifi_descriptors(struct device *dev,
+						const char *label)
+{
+}
+#endif
+
 static int ath79_gpio_probe(struct platform_device *pdev)
 {
 	struct ath79_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -291,7 +332,11 @@ static int ath79_gpio_probe(struct platform_device *pdev)
 		girq->handler = handle_simple_irq;
 	}
 
-	return devm_gpiochip_add_data(dev, &ctrl->gc, ctrl);
+	err = devm_gpiochip_add_data(dev, &ctrl->gc, ctrl);
+	if (err)
+		return err;
+
+	return ath79_gpio_register_wifi_descriptors(dev, ctrl->gc.label);
 }
 
 static struct platform_driver ath79_gpio_driver = {
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 5982e0db45f9..ee6705836746 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -20,7 +20,7 @@
 #include <linux/time.h>
 #include <linux/bitops.h>
 #include <linux/etherdevice.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <asm/unaligned.h>
 
 #include "hw.h"
@@ -2727,19 +2727,25 @@ static void ath9k_hw_gpio_cfg_output_mux(struct ath_hw *ah, u32 gpio, u32 type)
 static void ath9k_hw_gpio_cfg_soc(struct ath_hw *ah, u32 gpio, bool out,
 				  const char *label)
 {
+	enum gpiod_flags flags = out ? GPIOD_OUT_LOW : GPIOD_IN;
+	struct gpio_desc *gpiod;
 	int err;
 
-	if (ah->caps.gpio_requested & BIT(gpio))
+	if (ah->gpiods[gpio])
 		return;
 
-	err = gpio_request_one(gpio, out ? GPIOF_OUT_INIT_LOW : GPIOF_IN, label);
-	if (err) {
+	/* Obtains a system specific GPIO descriptor from another GPIO controller */
+	gpiod = devm_gpiod_get_index(ah->dev, NULL, gpio, flags);
+
+	if (IS_ERR(gpiod)) {
+		err = PTR_ERR(gpiod);
 		ath_err(ath9k_hw_common(ah), "request GPIO%d failed:%d\n",
 			gpio, err);
 		return;
 	}
 
-	ah->caps.gpio_requested |= BIT(gpio);
+	gpiod_set_consumer_name(gpiod, label);
+	ah->gpiods[gpio] = gpiod;
 }
 
 static void ath9k_hw_gpio_cfg_wmac(struct ath_hw *ah, u32 gpio, bool out,
@@ -2800,11 +2806,6 @@ void ath9k_hw_gpio_free(struct ath_hw *ah, u32 gpio)
 		return;
 
 	WARN_ON(gpio >= ah->caps.num_gpio_pins);
-
-	if (ah->caps.gpio_requested & BIT(gpio)) {
-		gpio_free(gpio);
-		ah->caps.gpio_requested &= ~BIT(gpio);
-	}
 }
 EXPORT_SYMBOL(ath9k_hw_gpio_free);
 
@@ -2832,8 +2833,8 @@ u32 ath9k_hw_gpio_get(struct ath_hw *ah, u32 gpio)
 			val = REG_READ(ah, AR_GPIO_IN(ah)) & BIT(gpio);
 		else
 			val = MS_REG_READ(AR, gpio);
-	} else if (BIT(gpio) & ah->caps.gpio_requested) {
-		val = gpio_get_value(gpio) & BIT(gpio);
+	} else if (ah->gpiods[gpio]) {
+		val = gpiod_get_value(ah->gpiods[gpio]);
 	} else {
 		WARN_ON(1);
 	}
@@ -2856,8 +2857,8 @@ void ath9k_hw_set_gpio(struct ath_hw *ah, u32 gpio, u32 val)
 			AR7010_GPIO_OUT : AR_GPIO_IN_OUT(ah);
 
 		REG_RMW(ah, out_addr, val << gpio, BIT(gpio));
-	} else if (BIT(gpio) & ah->caps.gpio_requested) {
-		gpio_set_value(gpio, val);
+	} else if (ah->gpiods[gpio]) {
+		gpiod_set_value(ah->gpiods[gpio], val);
 	} else {
 		WARN_ON(1);
 	}
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index 450ab19b1d4e..1eb4ff8955ae 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -19,6 +19,7 @@
 
 #include <linux/if_ether.h>
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/io.h>
 #include <linux/firmware.h>
 
@@ -302,7 +303,6 @@ struct ath9k_hw_capabilities {
 	u8 max_rxchains;
 	u8 num_gpio_pins;
 	u32 gpio_mask;
-	u32 gpio_requested;
 	u8 rx_hp_qdepth;
 	u8 rx_lp_qdepth;
 	u8 rx_status_len;
@@ -783,6 +783,7 @@ struct ath_hw {
 	struct ath9k_hw_capabilities caps;
 	struct ath9k_channel channels[ATH9K_NUM_CHANNELS];
 	struct ath9k_channel *curchan;
+	struct gpio_desc *gpiods[32];
 
 	union {
 		struct ar5416_eeprom_def def;

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

Best regards,
-- 
Linus Walleij <linus.walleij@xxxxxxxxxx>