[PATCH v2] gpio: search gpio-line-names property in dm_gpio_lookup_name

[Rasmus Villemoes]

In scripts as well as interactively, it's much nicer to be able to
refer to GPIOs via their names defined in the device tree property
"gpio-line-names", instead of the rather opaque names derived from the
bank name with a _xx suffix. E.g.

  gpio read factory_reset FACTORY_RESET
  if test $factory_reset = 1 ; then ...

versus

  gpio read factory_reset gpio at 481ac000_16
  if test $factory_reset = 1 ; then ...

This is also consistent with the move on the linux/userspace side towards
using line names instead of legacy chip+offset or the even more legacy
global gpio numbering in sysfs.

As this seems to only add about ~50 bytes of code to U-Boot proper,
and dm_gpio_lookup_name() most often ends up being GC'ed for SPL, so
adds no overhead there, adding yet another config knob (or two, if it
also needed an SPL variant) for this does not seem warranted.

Signed-off-by: Rasmus Villemoes <ravi at prevas.dk>
---

v2: guard the the dev_read_stringlist_search() call by
CONFIG_IS_ENABLED(OF_CONTROL) to avoid link failure on !OF_CONTROL
platforms.

 drivers/gpio/gpio-uclass.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 3d9f8b32b8d..f0d46417159 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -164,7 +164,7 @@ int dm_gpio_lookup_name(const char *name, struct gpio_desc *desc)
 	for (uclass_first_device(UCLASS_GPIO, &dev);
 	     dev;
 	     uclass_next_device(&dev)) {
-		int len;
+		int len, ret;
 
 		uc_priv = dev_get_uclass_priv(dev);
 		if (numeric != -1) {
@@ -188,6 +188,15 @@ int dm_gpio_lookup_name(const char *name, struct gpio_desc *desc)
 		 */
 		if (!dm_gpio_lookup_label(name, uc_priv, &offset))
 			break;
+
+		/* Also search the "gpio-line-names" property in DT for a match. */
+		if (CONFIG_IS_ENABLED(OF_CONTROL)) {
+			ret = dev_read_stringlist_search(dev, "gpio-line-names", name);
+			if (ret >= 0) {
+				offset = ret;
+				break;
+			}
+		}
 	}
 
 	if (!dev)
-- 
2.51.0