On Mon, Jan 26, 2015 at 02:37:24PM +0000, Mark Rutland wrote:

On Mon, Jan 26, 2015 at 02:29:33PM +0000, Mika Westerberg wrote:

quoted

The HID over I2C specification allows to have the interrupt for a HID
device to be GPIO instead of directly connected to the IO-APIC.

Add support for this so that when the driver does not find proper interrupt
number from the I2C client structure we check if the device has property
named "gpios". This is then assumed to be the GPIO that serves as an
interrupt for the device.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 .../devicetree/bindings/hid/hid-over-i2c.txt       |  5 +-
 drivers/hid/i2c-hid/i2c-hid.c                      | 70 ++++++++++++++++------
 2 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/Documentation/devicetree/bindings/hid/hid-over-i2c.txt b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt
index 488edcb264c4..8f4a99dad3b9 100644
--- a/Documentation/devicetree/bindings/hid/hid-over-i2c.txt
+++ b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt

@@ -15,7 +15,10 @@ Required properties:
 - reg: i2c slave address
 - hid-descr-addr: HID descriptor address
 - interrupt-parent: the phandle for the interrupt controller
-- interrupts: interrupt line
+- interrupts: interrupt line if the device uses IO-APIC interrupts
+
+Optional properties:
+- gpios: GPIO used as an interrupt if the device uses GPIO interrupts

Elsewhere we've said that for a GPIO acting as an interrupt line, GPIO
controller should be marked as an interrupt-controller, and the GPIO
described as an interrupt line. That also gets you the appropriate
configuration for the GPIO as an interrupt.

Does this GPIO serve any other purpose than an ersatz interrupt line?

It is just an interrupt.

If not, it should probably be described as an interrupt. From the PoV of
this device, it's just an interrupt controller hooked up to the
interrupt pin.

What I'm trying to do is to get a GPIO that is described in ACPI (as
GpioInt() in _CRS) to be supported in this driver using gpiolib like
this:

	desc = gpiod_get(&client->dev, NULL);

This calls to find "gpios" property which ends up finding the GpioInt()
in _CRS.