gpio: flush direction status in gpiochip_lock_as_irq()

As irqchip and gpiochip functions are orthogonal, the IRQ
set-up or something else can have changed the direction of
the GPIO line from what the GPIO descriptor knows when we
get into gpiochip_lock_as_irq(). Make sure to re-read the
direction setting if we have the .get_direction() callback
enabled for the chip.

Else we get problems like this:

iio iio:device2: interrupts on the rising edge
gpio gpiochip2: (8012e080.gpio): gpiochip_lock_as_irq:
  tried to flag a GPIO set as output for IRQ
gpio gpiochip2: (8012e080.gpio): unable to lock HW IRQ 0 for IRQ
genirq: Failed to request resources for l3g4200d-trigger
  (irq 111) on irqchip nmk1-32-63
iio iio:device2: failed to request trigger IRQ.
st-gyro-i2c: probe of 2-0068 failed with error -22

Fixes: 72d320006177 ("gpio: set up initial state from .get_direction()")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d407f904a31c..e901d2666b46 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2066,17 +2066,30 @@ EXPORT_SYMBOL_GPL(gpiod_to_irq);
  */
 int gpiochip_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
 {
-        if (offset >= chip->ngpio)
-                return -EINVAL;
+        struct gpio_desc *desc;
+
+        desc = gpiochip_get_desc(chip, offset);
+        if (IS_ERR(desc))
+                return PTR_ERR(desc);
+
+        /* Flush direction if something changed behind our back */
+        if (chip->get_direction) {
+                int dir = chip->get_direction(chip, offset);
+
+                if (dir)
+                        clear_bit(FLAG_IS_OUT, &desc->flags);
+                else
+                        set_bit(FLAG_IS_OUT, &desc->flags);
+        }
 
-        if (test_bit(FLAG_IS_OUT, &chip->gpiodev->descs[offset].flags)) {
+        if (test_bit(FLAG_IS_OUT, &desc->flags)) {
                 chip_err(chip,
                           "%s: tried to flag a GPIO set as output for IRQ\n",
                           __func__);
                 return -EIO;
         }
 
-        set_bit(FLAG_USED_AS_IRQ, &chip->gpiodev->descs[offset].flags);
+        set_bit(FLAG_USED_AS_IRQ, &desc->flags);
         return 0;
 }
 EXPORT_SYMBOL_GPL(gpiochip_lock_as_irq);