Hi Rob,
Quoting Rob Herring <robh@xxxxxxxxxx>:
On Thu, Nov 22, 2018 at 3:49 AM Tom Burkart <tom@xxxxxxxxxx> wrote:
This patch implements the device tree changes required for the pps
echo functionality for pps-gpio, that sysfs claims is available
already.
This patch was originally written by Lukas Senger as part of a masters
thesis project and modified for inclusion into the linux kernel by Tom
Burkart.
Signed-off-by: Lukas Senger <lukas@xxxxxxxxxxxx>
Signed-off-by: Tom Burkart <tom@xxxxxxxxxx>
---
Documentation/devicetree/bindings/pps/pps-gpio.txt | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.txt
b/Documentation/devicetree/bindings/pps/pps-gpio.txt
index 1155d49c2699..e09f6f2405c5 100644
--- a/Documentation/devicetree/bindings/pps/pps-gpio.txt
+++ b/Documentation/devicetree/bindings/pps/pps-gpio.txt
@@ -7,10 +7,15 @@ Required properties:
- compatible: should be "pps-gpio"
- gpios: one PPS GPIO in the format described by ../gpio/gpio.txt
+Additional required properties for the PPS ECHO functionality:
+- echo-gpios: one PPS ECHO GPIO in the format described by ../gpio/gpio.txt
+- echo-active-ms: duration in ms of the active portion of the echo pulse
+
Optional properties:
- assert-falling-edge: when present, assert is indicated by a falling edge
(instead of by a rising edge)
- capture-clear: when present, also capture the PPS clear event
+- invert-pps-echo: when present, invert the PPS ECHO pulse
Why do you need this? Can't you just make the echo gpio GPIO_ACTIVE_LOW?
BTW, using the flag probably should have been done for
'assert-falling-edge' as well.
The hardware I use expects a positive-going echo pulse, however, it
was really easy to give users the option to have it inverted in case
they use different hardware that expects a negative-going edge.
I may well be needing this option myself if I find that the GPS I am
using produces better results for negative-going edges than
positive-going edges.
Tom
