gpiolib-acpi: Preserve non direction flags when updating gpiod_flags

__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.
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib-acpi.c

@@ -474,6 +474,9 @@ 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;
 
 	/*
@@ -494,7 +497,7 @@ __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 = (*flags & ~mask) | (update & mask);
 	}
 	return ret;
 }