linux-kernel - [PATCH v2 2/2] gpiolib: check the 'ngpios' property in core gpiolib code

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Message-Id: <20211118132317.15898-2-brgl@bgdev.pl>
Date:   Thu, 18 Nov 2021 14:23:17 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: [PATCH v2 2/2] gpiolib: check the 'ngpios' property in core gpiolib code

Several drivers read the 'ngpios' device property on their own, but
since it's defined as a standard GPIO property in the device tree bindings
anyway, it's a good candidate for generalization. If the driver didn't
set its gc->ngpio, try to read the 'ngpios' property from the GPIO
device's firmware node before bailing out.

Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
---
v1 -> v2:
- use device_property_read_u32() instead of fwnode_property_read_u32()
- reverse the error check logic

 drivers/gpio/gpiolib.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 20d63028b85c..0746615073c6 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -598,6 +598,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	struct gpio_device *gdev;
 	unsigned long flags;
 	unsigned int i;
+	u32 ngpios;
 
 	/*
 	 * First: allocate and populate the internal stat container, and
@@ -646,9 +647,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	}
 
 	if (gc->ngpio == 0) {
-		chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
-		ret = -EINVAL;
-		goto err_free_descs;
+		ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
+		if (ret) {
+			chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
+			ret = -EINVAL;
+			goto err_free_descs;
+		}
+
+		gc->ngpio = ngpios;
 	}
 
 	if (gc->ngpio > FASTPATH_NGPIO)
-- 
2.25.1