[PATCH] gpio / ACPI: ignore GpioInt() GPIOs when requesting GPIO_OUT_*

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

From: Dmitry Torokhov <dtor@chromium.org>

When firmware does not use _DSD properties that allow properly name GPIO
resources, the kernel falls back on parsing _CRS resources, and will
return entries described as GpioInt() as general purpose GPIOs even
though they are meant to be used simply as interrupt sources for the
device:

Device (ETSA)
{
	Name (_HID, "ELAN0001")
	...

	Method(_CRS, 0x0, NotSerialized)
	{
		Name(BUF0,ResourceTemplate ()
		{
			I2CSerialBus(
				0x10,                     /* SlaveAddress */
				ControllerInitiated,      /* SlaveMode */
				400000,                   /* ConnectionSpeed */
				AddressingMode7Bit,       /* AddressingMode */
				"\\_SB.I2C1",             /* ResourceSource */
			)
			GpioInt (Edge, ActiveLow, ExclusiveAndWake, PullNone,,
				 "\\_SB.GPSW") { BOARD_TOUCH_GPIO_INDEX }
		} )
		Return (BUF0)
	}
...
}

This gives troubles with drivers such as Elan Touchscreen driver
(elants_i2c) that uses devm_gpio_get to look up "reset" GPIO line and
decide whether the driver is responsible for powering up and resetting
the device or firmware is. In the above case the lookup succeeds, we map
GPIO as output and later fail to request client->irq interrupt that is
mapped to the same GPIO.

Let's ignore resources described as GpioInt() when requesting output
GPIO (but allow them when requesting GPIOD_ASIS or GPIOD_IN as some
drivers - i2c-hid - do request GPIO as input and then map it to
interrupt with gpiod_to_irq).

BUG=chrome-os-partner:51154
TEST=Boot Cyan, verify touchscreen work

Change-Id: Id20c730b937dce8a4135d2b64c8d798372d20e82
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
---
 drivers/gpio/gpiolib.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 7206553..4a0e66b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2231,9 +2231,11 @@ static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
 	return desc;
 }
 
-static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id,
+static struct gpio_desc *acpi_find_gpio(struct device *dev,
+					const char *con_id,
 					unsigned int idx,
-					enum gpio_lookup_flags *flags)
+					enum gpiod_flags flags,
+					enum gpio_lookup_flags *lookupflags)
 {
 	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpi_gpio_info info;
@@ -2264,10 +2266,16 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id,
 		desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
 		if (IS_ERR(desc))
 			return desc;
+
+		if ((flags == GPIOD_OUT_LOW || flags == GPIOD_OUT_HIGH) &&
+		    info.gpioint) {
+			dev_dbg(dev, "refusing GpioInt() entry when doing GPIOD_OUT_* lookup\n");
+			return ERR_PTR(-ENOENT);
+		}
 	}
 
 	if (info.polarity == GPIO_ACTIVE_LOW)
-		*flags |= GPIO_ACTIVE_LOW;
+		*lookupflags |= GPIO_ACTIVE_LOW;
 
 	return desc;
 }
@@ -2530,7 +2538,7 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
 			desc = of_find_gpio(dev, con_id, idx, &lookupflags);
 		} else if (ACPI_COMPANION(dev)) {
 			dev_dbg(dev, "using ACPI for GPIO lookup\n");
-			desc = acpi_find_gpio(dev, con_id, idx, &lookupflags);
+			desc = acpi_find_gpio(dev, con_id, idx, flags, &lookupflags);
 		}
 	}
 
-- 
2.8.0.rc3.226.g39d4020


-- 
Dmitry