[PATCH 5.10 107/157] gpiolib: Read "gpio-line-names" from a firmware node

Greg Kroah-Hartman
2021-03-22T12:53:14Z

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

[ Upstream commit b41ba2ec54a70908067034f139aa23d0dd2985ce ]

On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
and iterates over all of its DT subnodes when registering each GPIO
bank gpiochip. Each gpiochip has:

- gpio_chip.parent = dev,
where dev is the device node of the pin controller
- gpio_chip.of_node = np,
which is the OF node of the GPIO bank

Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.

The original code behaved correctly, as it extracted the "gpio-line-names"
from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.

To achieve the same behaviour, read property from the firmware node.

Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
Reported-by: Marek Vasut <marex@denx.de>
Reported-by: Roman Guskov <rguskov@dh-electronics.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Marek Vasut <marex@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpio/gpiolib.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 0a2c4adcd833..af5bb8fedfea 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -364,22 +364,18 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
*
* Looks for device property "gpio-line-names" and if it exists assigns
* GPIO line names for the chip. The memory allocated for the assigned
- * names belong to the underlying software node and should not be released
+ * names belong to the underlying firmware node and should not be released
* by the caller.
*/
static int devprop_gpiochip_set_names(struct gpio_chip *chip)
{
struct gpio_device *gdev = chip->gpiodev;
- struct device *dev = chip->parent;
+ struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
const char **names;
int ret, i;
int count;

- /* GPIO chip may not have a parent device whose properties we inspect. */
- if (!dev)
- return 0;
-
- count = device_property_string_array_count(dev, "gpio-line-names");
+ count = fwnode_property_string_array_count(fwnode, "gpio-line-names");
if (count < 0)
return 0;

@@ -393,7 +389,7 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip)
if (!names)
return -ENOMEM;

- ret = device_property_read_string_array(dev, "gpio-line-names",
+ ret = fwnode_property_read_string_array(fwnode, "gpio-line-names",
names, count);
if (ret < 0) {
dev_warn(&gdev->dev, "failed to read GPIO line names\n");
--
2.30.1