gpio: Add missing open drain/source handling to gpiod_set_value_cansleep()

Since commit f11a0446 ("i2c: gpio: Enable working over slow
can_sleep GPIOs"), probing the i2c RTC connected to an i2c-gpio bus on
r8a7740/armadillo fails with:

    rtc-s35390a 0-0030: error resetting chip
    rtc-s35390a: probe of 0-0030 failed with error -5

More debug code reveals:

    i2c i2c-0: master_xfer[0] R, addr=0x30, len=1
    i2c i2c-0: NAK from device addr 0x30 msg #0
    s35390a_get_reg: ret = -6

Commit 02e47980 ("gpio: Alter semantics of *raw* operations to
actually be raw") moved open drain/source handling from
gpiod_set_raw_value_commit() to gpiod_set_value(), but forgot to take
into account that gpiod_set_value_cansleep() also needs this handling.
The i2c protocol mandates that i2c signals are open drain, hence i2c
communication fails.

Fix this by adding the missing handling to gpiod_set_value_cansleep(),
using a new common helper gpiod_set_value_nocheck().

Fixes: 02e47980 ("gpio: Alter semantics of *raw* operations to actually be raw")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
[removed underscore syntax, added kerneldoc]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -2892,6 +2892,27 @@ void gpiod_set_raw_value(struct gpio_desc *desc, int value)
 }
 EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
 
+/**
+ * gpiod_set_value_nocheck() - set a GPIO line value without checking
+ * @desc: the descriptor to set the value on
+ * @value: value to set
+ *
+ * This sets the value of a GPIO line backing a descriptor, applying
+ * different semantic quirks like active low and open drain/source
+ * handling.
+ */
+static void gpiod_set_value_nocheck(struct gpio_desc *desc, int value)
+{
+	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
+		value = !value;
+	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
+		gpio_set_open_drain_value_commit(desc, value);
+	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
+		gpio_set_open_source_value_commit(desc, value);
+	else
+		gpiod_set_raw_value_commit(desc, value);
+}
+
 /**
  * gpiod_set_value() - assign a gpio's value
  * @desc: gpio whose value will be assigned
@@ -2906,16 +2927,8 @@ EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
 void gpiod_set_value(struct gpio_desc *desc, int value)
 {
 	VALIDATE_DESC_VOID(desc);
-	/* Should be using gpiod_set_value_cansleep() */
 	WARN_ON(desc->gdev->chip->can_sleep);
-	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
-		value = !value;
-	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
-		gpio_set_open_drain_value_commit(desc, value);
-	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
-		gpio_set_open_source_value_commit(desc, value);
-	else
-		gpiod_set_raw_value_commit(desc, value);
+	gpiod_set_value_nocheck(desc, value);
 }
 EXPORT_SYMBOL_GPL(gpiod_set_value);
 
@@ -3243,9 +3256,7 @@ void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
 {
 	might_sleep_if(extra_checks);
 	VALIDATE_DESC_VOID(desc);
-	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
-		value = !value;
-	gpiod_set_raw_value_commit(desc, value);
+	gpiod_set_value_nocheck(desc, value);
 }
 EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep);