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From: Linus Walleij <linus.walleij@linaro.org>
Date: Wed, 31 Jan 2024 23:37:20 +0100
Subject: [PATCH 1/6] wifi: ath9k: Obtain system GPIOS from descriptors
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Message-Id: <20240131-descriptors-wireless-v1-1-e1c7c5d68746@linaro.org>
References: <20240131-descriptors-wireless-v1-0-e1c7c5d68746@linaro.org>
In-Reply-To: <20240131-descriptors-wireless-v1-0-e1c7c5d68746@linaro.org>
To: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>, 
 Kalle Valo <kvalo@kernel.org>, Arend van Spriel <aspriel@gmail.com>, 
 Franky Lin <franky.lin@broadcom.com>, 
 Hante Meuleman <hante.meuleman@broadcom.com>, 
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>, 
 Arnd Bergmann <arnd@arndb.de>, Lee Jones <lee@kernel.org>, 
 Brian Norris <briannorris@chromium.org>, 
 Srinivasan Raju <srini.raju@purelifi.com>
Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, 
 brcm80211-dev-list.pdl@broadcom.com, 
 Linus Walleij <linus.walleij@linaro.org>

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.

My best guess is that everyone actually using this driver has
support for the local (custom) GPIO API and the bit in
h->caps.gpio_mask is always set for any GPIO the driver may
try to obtain, so this facility to use system-wide GPIOs is
actually unused and could be deleted.

Anyway: I cannot know if this is really the case, so implement
a fallback handling using GPIO descriptors obtained from the
ah->dev device indexed 0..31. These can for example be passed
in the device tree, ACPI or through board files. I doubt that
anyone will use them, but this makes it possible to obtain a
system-wide GPIO for any of the 0..31 GPIOs potentially
requested by the driver.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/net/wireless/ath/ath9k/hw.c | 29 +++++++++++++++--------------
 drivers/net/wireless/ath/ath9k/hw.h |  3 ++-
 2 files changed, 17 insertions(+), 15 deletions(-)

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;

-- 
2.34.1