[PATCH v2] serial: mctrl_gpio: Support all GPIO suffixes (gpios vs gpio)

[Stefan Roese <sr@denx.de>]

This patch fixes a backward compatibility issue, when boards use the
old style GPIO suffix "-gpio" instead of the new "-gpios". This
potential problem has been introduced by commit d99482673f95 ("serial:
mctrl_gpio: Check if GPIO property exisits before requesting it").

This patch now fixes this issue by using gpiod_count() which iterates
over all supported GPIO suffixes (thanks to Linus for suggesting this).

With this change, the local string is not needed any more. This way
we can remove the allocation in the loop.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Pavel Machek <pavel@denx.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v2
- Use gpiod_count() to check if the GPIO exists (Linus)
- Remove the now unnecessary malloc in the loop (kasprintf)

 drivers/tty/serial/serial_mctrl_gpio.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index 2b400189be91..ce73b142c66b 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -117,18 +117,11 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
 
 	for (i = 0; i < UART_GPIO_MAX; i++) {
 		enum gpiod_flags flags;
-		char *gpio_str;
-		bool present;
+		int count;
 
 		/* Check if GPIO property exists and continue if not */
-		gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
-				     mctrl_gpios_desc[i].name);
-		if (!gpio_str)
-			continue;
-
-		present = device_property_present(dev, gpio_str);
-		kfree(gpio_str);
-		if (!present)
+		count = gpiod_count(dev, mctrl_gpios_desc[i].name);
+		if (count <= 0)
 			continue;
 
 		if (mctrl_gpios_desc[i].dir_out)
-- 
2.22.1