This patch implements the pps echo functionality for pps-gpio, that
sysfs claims is available already.
Configuration is done via device tree bindings.
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
Signed-off-by: Tom Burkart
---
drivers/pps/clients/pps-gpio.c | 89 --
include/linux/pps-gpio.h | 2 +
2 files changed, 88 insertions(+), 3 deletions(-)
diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
index 4e5e9229814b..f00f5ca9f9ad 100644
--- a/drivers/pps/clients/pps-gpio.c
+++ b/drivers/pps/clients/pps-gpio.c
@@ -35,6 +35,8 @@
#include
#include
#include
+#include
+#include
/* Info for each registered platform device */
struct pps_gpio_device_data {
@@ -42,8 +44,12 @@ struct pps_gpio_device_data {
struct pps_device *pps; /* PPS source device */
struct pps_source_info info;/* PPS source information */
struct gpio_desc *gpio_pin; /* GPIO port descriptors */
+ struct gpio_desc *echo_pin;
+ struct timer_list echo_timer; /* timer to reset echo active state */
bool assert_falling_edge;
bool capture_clear;
+ unsigned int echo_active_ms;/* PPS echo active duration */
+ unsigned long echo_timeout; /* timer timeout value in jiffies */
};
/*
@@ -64,19 +70,57 @@ static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
rising_edge = gpiod_get_value(info->gpio_pin);
if ((rising_edge && !info->assert_falling_edge) ||
(!rising_edge && info->assert_falling_edge))
- pps_event(info->pps, , PPS_CAPTUREASSERT, NULL);
+ pps_event(info->pps, , PPS_CAPTUREASSERT, data);
else if (info->capture_clear &&
((rising_edge && info->assert_falling_edge) ||
(!rising_edge && !info->assert_falling_edge)))
- pps_event(info->pps, , PPS_CAPTURECLEAR, NULL);
+ pps_event(info->pps, , PPS_CAPTURECLEAR, data);
return IRQ_HANDLED;
}
+static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
+{
+ /* add_timer() needs to write into info->echo_timer */
+ struct pps_gpio_device_data *info;
+
+ info = data;
+
+ switch (event) {
+ case PPS_CAPTUREASSERT:
+ if (pps->params.mode & PPS_ECHOASSERT)
+ gpiod_set_value(info->echo_pin, 1);
+ break;
+
+ case PPS_CAPTURECLEAR:
+ if (pps->params.mode & PPS_ECHOCLEAR)
+ gpiod_set_value(info->echo_pin, 1);
+ break;
+ }
+
+ /* fire the timer */
+ if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
+ info->echo_timer.expires = jiffies + info->echo_timeout;
+ add_timer(>echo_timer);
+ }
+}
+
+/* Timer callback to reset the echo pin to the inactive state */
+static void pps_gpio_echo_timer_callback(struct timer_list *t)
+{
+ const struct pps_gpio_device_data *info;
+
+ info = from_timer(info, t, echo_timer);
+
+ gpiod_set_value(info->echo_pin, 0);
+}
+
static int pps_gpio_setup(struct platform_device *pdev)
{
struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
struct device_node *np = pdev->dev.of_node;
+ int ret;
+ u32 value;
data->gpio_pin = devm_gpiod_get(>dev,
NULL, /* request "gpios" */
@@ -87,6 +131,33 @@ static int pps_gpio_setup(struct platform_device *pdev)
return PTR_ERR(data->gpio_pin);
}
+ data->echo_pin = devm_gpiod_get_optional(>dev,
+ "echo",
+ GPIOD_OUT_LOW);
+ if (data->echo_pin) {
+ if (IS_ERR(data->echo_pin)) {
+ dev_err(>dev, "failed to request ECHO GPIO\n");
+ return PTR_ERR(data->echo_pin);
+ }
+
+ ret = of_property_read_u32(np,
+ "echo-active-ms",
+ );
+ if (ret) {
+ dev_err(>dev,
+ "failed to get echo-active-ms from OF\n");
+ return ret;
+ }
+ data->echo_active_ms = value;
+ /* sanity check on echo_active_ms */
+ if (!data->echo_active_ms || data->echo_active_ms > 999) {
+ dev_err(>dev,
+ "echo-active-ms: %u - bad value from OF\n",
+ data->echo_active_ms);
+ return -EINVAL;
+ }
+ }
+
if (of_property_read_bool(np, "assert-falling-edge"))
data->assert_falling_edge = true;
return 0;
@@ -122,9 +193,11 @@ static int
