linux-hardening - [PATCH v3 10/10] regulator: make the subsystem aware of shared GPIOs

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Message-Id: <20251029-gpio-shared-v3-10-71c568acf47c@linaro.org>
Date: Wed, 29 Oct 2025 12:20:46 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Kees Cook <kees@...nel.org>, Mika Westerberg <westeri@...nel.org>, 
 Dmitry Torokhov <dmitry.torokhov@...il.com>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Andy Shevchenko <andy@...nel.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
 Srinivas Kandagatla <srini@...nel.org>, Liam Girdwood <lgirdwood@...il.com>, 
 Mark Brown <broonie@...nel.org>, Jaroslav Kysela <perex@...ex.cz>, 
 Takashi Iwai <tiwai@...e.com>, Alexey Klimov <alexey.klimov@...aro.org>
Cc: linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v3 10/10] regulator: make the subsystem aware of shared
 GPIOs

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

GPIOLIB is now aware of shared GPIOs and - for platforms where access to
such pins is managed internally - we don't need to keep track of the
enable count.

Once all users in the kernel switch to using the new mechanism, we'll be
able to drop the internal counting of users from the regulator code.

Acked-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/regulator/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 84bc38911dba308539a25dd3af30a5c24802b890..e13cf5e120466cebc4d3f8400b89be07d3303338 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2737,6 +2737,13 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
 
 	mutex_lock(&regulator_list_mutex);
 
+	if (gpiod_is_shared(gpiod))
+		/*
+		 * The sharing of this GPIO pin is managed internally by
+		 * GPIOLIB. We don't need to keep track of its enable count.
+		 */
+		goto skip_compare;
+
 	list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
 		if (gpiod_is_equal(pin->gpiod, gpiod)) {
 			rdev_dbg(rdev, "GPIO is already used\n");
@@ -2749,6 +2756,7 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
 		return -ENOMEM;
 	}
 
+skip_compare:
 	pin = new_pin;
 	new_pin = NULL;
 

-- 
2.48.1