ath79: add support for reset key on MikroTik RB912UAG-2HPnD

On MikroTik RB91x board series a reset key shares SoC gpio
line #15 with NAND ALE and NAND IO7. So we need a custom
gpio driver to manage this non-trivial connection schema.
Also rb91x-nand needs to have an ability to disable a polling
of the key while it works with NAND.

While we've been integrating rb91x-key into a firmware, we've
figured out that:
* In the gpio-latch driver we need to add a "cansleep" suffix to
several gpiolib calls,
* When gpio-latch and rb91x-nand fail to get a gpio and an error
is -EPROBE_DEFER, they shouldn't report about this, since this
actually is not an error and occurs when the gpio-latch probe
function is called before the rb91x-key probe.
We fix these related things here too.

Signed-off-by: Denis Kalashnikov <denis281089@gmail.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/target/linux/ath79/files/drivers/gpio/gpio-latch.c b/target/linux/ath79/files/drivers/gpio/gpio-latch.c
index f3545a663e..976e683230 100644
--- a/target/linux/ath79/files/drivers/gpio/gpio-latch.c
+++ b/target/linux/ath79/files/drivers/gpio/gpio-latch.c
@@ -62,7 +62,7 @@ gpio_latch_get(struct gpio_chip *gc, unsigned offset)
 	int ret;
 
 	gpio_latch_lock(glc, false);
-	ret = gpiod_get_value(glc->gpios[offset]);
+	ret = gpiod_get_raw_value_cansleep(glc->gpios[offset]);
 	gpio_latch_unlock(glc, false);
 
 	return ret;
@@ -81,7 +81,7 @@ gpio_latch_set(struct gpio_chip *gc, unsigned offset, int value)
 	}
 
 	gpio_latch_lock(glc, enable_latch);
-	gpiod_set_raw_value(glc->gpios[offset], value);
+	gpiod_set_raw_value_cansleep(glc->gpios[offset], value);
 	gpio_latch_unlock(glc, disable_latch);
 }
 
@@ -133,8 +133,10 @@ static int gpio_latch_probe(struct platform_device *pdev)
 		glc->gpios[i] = devm_gpiod_get_index_optional(dev, NULL, i,
 			GPIOD_OUT_LOW);
 		if (IS_ERR(glc->gpios[i])) {
-			dev_err(dev, "failed to get gpio %d: %d\n", i,
-				PTR_ERR(glc->gpios[i]));
+			if (PTR_ERR(glc->gpios[i]) != -EPROBE_DEFER) {
+				dev_err(dev, "failed to get gpio %d: %d\n", i,
+					PTR_ERR(glc->gpios[i]));
+			}
 			return PTR_ERR(glc->gpios[i]);
 		}
 	}