linux-kernel - [PATCH 10/15 v3] gpio: devres: Handle nonexclusive GPIOs

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Date:   Wed,  5 Dec 2018 13:47:16 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH 10/15 v3] gpio: devres: Handle nonexclusive GPIOs

When we get a nonexeclusive GPIO descriptor using managed
resources, we should only add it to the list of managed
resources once: on the first user. Augment the
devm_gpiod_get_index() and devm_gpiod_get_from_of_node()
calls to account for this by checking if the descriptor
is already resource managed before we proceed to allocate
a new resource management struct.

Cc: Mark Brown <broonie@...nel.org>
Cc: Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>
Fixes: b0ce7b29bfcd ("regulator/gpio: Allow nonexclusive GPIO access")
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
ChangeLog v1->v3:
- New patch.
- This fix is in response to an issue Marek saw in the fixups
  for resource-managed GPIO descriptors used with ena_gpiod
  in the regulator subsystem.
- I first thought to apply it to the GPIO tree directly, but
  since it is not a regression it is better to put it into
  the regulator tree with the rest of the patches.
---
 drivers/gpio/gpiolib-devres.c | 50 ++++++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
index 01959369360b..a57e968025a8 100644
--- a/drivers/gpio/gpiolib-devres.c
+++ b/drivers/gpio/gpiolib-devres.c
@@ -98,15 +98,28 @@ struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
 	struct gpio_desc **dr;
 	struct gpio_desc *desc;
 
+	desc = gpiod_get_index(dev, con_id, idx, flags);
+	if (IS_ERR(desc))
+		return desc;
+
+	/*
+	 * For non-exclusive GPIO descriptors, check if this descriptor is
+	 * already under resource management by this device.
+	 */
+	if (flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
+		struct devres *dres;
+
+		dres = devres_find(dev, devm_gpiod_release,
+				   devm_gpiod_match, desc);
+		if (dres)
+			return desc;
+	}
+
 	dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
 			  GFP_KERNEL);
-	if (!dr)
+	if (!dr) {
+		gpiod_put(desc);
 		return ERR_PTR(-ENOMEM);
-
-	desc = gpiod_get_index(dev, con_id, idx, flags);
-	if (IS_ERR(desc)) {
-		devres_free(dr);
-		return desc;
 	}
 
 	*dr = desc;
@@ -140,15 +153,28 @@ struct gpio_desc *devm_gpiod_get_from_of_node(struct device *dev,
 	struct gpio_desc **dr;
 	struct gpio_desc *desc;
 
+	desc = gpiod_get_from_of_node(node, propname, index, dflags, label);
+	if (IS_ERR(desc))
+		return desc;
+
+	/*
+	 * For non-exclusive GPIO descriptors, check if this descriptor is
+	 * already under resource management by this device.
+	 */
+	if (dflags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
+		struct devres *dres;
+
+		dres = devres_find(dev, devm_gpiod_release,
+				   devm_gpiod_match, desc);
+		if (dres)
+			return desc;
+	}
+
 	dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
 			  GFP_KERNEL);
-	if (!dr)
+	if (!dr) {
+		gpiod_put(desc);
 		return ERR_PTR(-ENOMEM);
-
-	desc = gpiod_get_from_of_node(node, propname, index, dflags, label);
-	if (IS_ERR(desc)) {
-		devres_free(dr);
-		return desc;
 	}
 
 	*dr = desc;
-- 
2.19.2