[PATCH] gpiolib-acpi: Preserve non direction flags when updating gpiod_flags

[Hans de Goede <hdegoede@xxxxxxxxxx>]

__acpi_gpio_update_gpiod_flags purpose is to make the gpiod_flags used
when requesting a GPIO match the restrictions from the ACPI resource,
as stored in acpi_gpio_info.flags.

But acpi_gpio_info.flags only contains direction info, and the
requester may have passed in special non-direction flags like
GPIOD_FLAGS_BIT_NONEXCLUSIVE, which we currently clobber.

This commit modifies __acpi_gpio_update_gpiod_flags to preserve these
special flags, so that a requested of an ACPI GPIO can e.g. pass
GPIOD_FLAGS_BIT_NONEXCLUSIV and have it work as intended.

Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
 drivers/gpio/gpiolib-acpi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 091a3784720d..a281f9409c06 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -469,6 +469,9 @@ acpi_gpio_to_gpiod_flags(const struct acpi_resource_gpio *agpio)
 static int
 __acpi_gpio_update_gpiod_flags(enum gpiod_flags *flags, enum gpiod_flags update)
 {
+	const enum gpiod_flags mask =
+		GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT |
+		GPIOD_FLAGS_BIT_DIR_VAL;
 	int ret = 0;
 
 	/*
@@ -489,7 +492,8 @@ __acpi_gpio_update_gpiod_flags(enum gpiod_flags *flags, enum gpiod_flags update)
 		if (((*flags & GPIOD_FLAGS_BIT_DIR_SET) && (diff & GPIOD_FLAGS_BIT_DIR_OUT)) ||
 		    ((*flags & GPIOD_FLAGS_BIT_DIR_OUT) && (diff & GPIOD_FLAGS_BIT_DIR_VAL)))
 			ret = -EINVAL;
-		*flags = update;
+		*flags &= ~mask;
+		*flags |= update & mask;
 	}
 	return ret;
 }
-- 
2.20.1