pps-gpio: add device-tree binding and support

Instead of allocating a struct pps_gpio_platform_data in the DT case,
store the necessary information in struct pps_gpio_device_data itself.
This avoids an additional allocation and the ifdef.  It also gets rid of
some indirection.

Also use dev_err instead of pr_err in the changed code.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.txt b/Documentation/devicetree/bindings/pps/pps-gpio.txt
new file mode 100644
index 000000000000..40bf9c3564a5
--- /dev/null
+++ b/Documentation/devicetree/bindings/pps/pps-gpio.txt
@@ -0,0 +1,20 @@
+Device-Tree Bindings for a PPS Signal on GPIO
+
+These properties describe a PPS (pulse-per-second) signal connected to
+a GPIO pin.
+
+Required properties:
+- compatible: should be "pps-gpio"
+- gpios: one PPS GPIO in the format described by ../gpio/gpio.txt
+
+Optional properties:
+- assert-falling-edge: when present, assert is indicated by a falling edge
+                       (instead of by a rising edge)
+
+Example:
+	pps {
+		compatible = "pps-gpio";
+		gpios = <&gpio2 6 0>;
+
+		assert-falling-edge;
+	};