linux-kernel - [PATCH v6 05/12] gpio: aggregator: refactor the code to add GPIO desc in the forwarder

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Message-Id: <20250520-aaeon-up-board-pinctrl-support-v6-5-dcb3756be3c6@bootlin.com>
Date: Tue, 20 May 2025 15:28:29 +0200
From: Thomas Richard <thomas.richard@...tlin.com>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
 Bartosz Golaszewski <brgl@...ev.pl>, 
 Geert Uytterhoeven <geert+renesas@...der.be>, Kees Cook <kees@...nel.org>, 
 Andy Shevchenko <andy@...nel.org>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 thomas.petazzoni@...tlin.com, DanieleCleri@...on.eu, GaryWang@...on.com.tw, 
 linux-hardening@...r.kernel.org, 
 Thomas Richard <thomas.richard@...tlin.com>
Subject: [PATCH v6 05/12] gpio: aggregator: refactor the code to add GPIO
 desc in the forwarder

Create a dedicated function to add a GPIO desc in the forwarder. Instead of
saving a GPIO descs array pointer, now the GPIO descs are passed one by one
to the forwarder which registers them in its own array. So after the call
of gpiochip_fwd_create(), the passed array can be free.

Reviewed-by: Andy Shevchenko <andy@...nel.org>
Signed-off-by: Thomas Richard <thomas.richard@...tlin.com>
---
 drivers/gpio/gpio-aggregator.c | 59 ++++++++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 19 deletions(-)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 754680fd810f..ed3fb6abec09 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -508,6 +508,10 @@ devm_gpiochip_fwd_alloc(struct device *dev, unsigned int ngpios)
 	if (!fwd)
 		return ERR_PTR(-ENOMEM);
 
+	fwd->descs = devm_kcalloc(dev, ngpios, sizeof(*fwd->descs), GFP_KERNEL);
+	if (!fwd->descs)
+		return ERR_PTR(-ENOMEM);
+
 	chip = &fwd->chip;
 
 	chip->label = dev_name(dev);
@@ -527,13 +531,43 @@ devm_gpiochip_fwd_alloc(struct device *dev, unsigned int ngpios)
 	return fwd;
 }
 
+static int gpiochip_fwd_desc_add(struct gpiochip_fwd *fwd,
+				 struct gpio_desc *desc,
+				 unsigned int offset)
+{
+	struct gpio_chip *parent = gpiod_to_chip(desc);
+	struct gpio_chip *chip = &fwd->chip;
+
+	if (offset > chip->ngpio)
+		return -EINVAL;
+
+	/*
+	 * If any of the GPIO lines are sleeping, then the entire forwarder
+	 * will be sleeping.
+	 * If any of the chips support .set_config(), then the forwarder will
+	 * support setting configs.
+	 */
+	if (gpiod_cansleep(desc))
+		chip->can_sleep = true;
+
+	if (parent && parent->set_config)
+		chip->set_config = gpio_fwd_set_config;
+
+	fwd->descs[offset] = desc;
+
+	dev_dbg(chip->parent, "%u => gpio %d irq %d\n", offset,
+		desc_to_gpio(desc), gpiod_to_irq(desc));
+
+	return 0;
+}
+
 /**
  * gpiochip_fwd_create() - Create a new GPIO forwarder
  * @dev: Parent device pointer
  * @ngpios: Number of GPIOs in the forwarder.
  * @descs: Array containing the GPIO descriptors to forward to.
- *         This array must contain @ngpios entries, and must not be deallocated
- *         before the forwarder has been destroyed again.
+ *         This array must contain @ngpios entries, and can be deallocated
+ *         as the forwarder has its own array.
  * @features: Bitwise ORed features as defined with FWD_FEATURE_*.
  *
  * This function creates a new gpiochip, which forwards all GPIO operations to
@@ -558,26 +592,12 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
 
 	chip = &fwd->chip;
 
-	/*
-	 * If any of the GPIO lines are sleeping, then the entire forwarder
-	 * will be sleeping.
-	 * If any of the chips support .set_config(), then the forwarder will
-	 * support setting configs.
-	 */
 	for (i = 0; i < ngpios; i++) {
-		struct gpio_chip *parent = gpiod_to_chip(descs[i]);
-
-		dev_dbg(dev, "%u => gpio %d irq %d\n", i,
-			desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));
-
-		if (gpiod_cansleep(descs[i]))
-			chip->can_sleep = true;
-		if (parent && parent->set_config)
-			chip->set_config = gpio_fwd_set_config;
+		error = gpiochip_fwd_desc_add(fwd, descs[i], i);
+		if (error)
+			return ERR_PTR(error);
 	}
 
-	fwd->descs = descs;
-
 	if (chip->can_sleep)
 		mutex_init(&fwd->mlock);
 	else
@@ -629,6 +649,7 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
 		return PTR_ERR(fwd);
 
 	platform_set_drvdata(pdev, fwd);
+	devm_kfree(dev, descs);
 	return 0;
 }
 

-- 
2.39.5