2 files changed, 87 insertions, 3 deletions

diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
index 4e5e9229814b..4b6418039387 100644
--- a/drivers/pps/clients/pps-gpio.c
+++ b/drivers/pps/clients/pps-gpio.c
@@ -35,6 +35,8 @@
 #include <linux/list.h>
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
 
 /* 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 +70,56 @@ 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, &ts, PPS_CAPTUREASSERT, NULL);
+                pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
         else if (info->capture_clear &&
                         ((rising_edge && info->assert_falling_edge) ||
                         (!rising_edge && !info->assert_falling_edge)))
-                pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
+                pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
 
         return IRQ_HANDLED;
 }
 
+/* This function will only be called when an ECHO GPIO is defined */
+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 = 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(&info->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(&pdev->dev,
                 NULL,   /* request "gpios" */
@@ -87,6 +130,33 @@ static int pps_gpio_setup(struct platform_device *pdev)
                 return PTR_ERR(data->gpio_pin);
         }
 
+        data->echo_pin = devm_gpiod_get_optional(&pdev->dev,
+                        "echo",
+                        GPIOD_OUT_LOW);
+        if (data->echo_pin) {
+                if (IS_ERR(data->echo_pin)) {
+                        dev_err(&pdev->dev, "failed to request ECHO GPIO\n");
+                        return PTR_ERR(data->echo_pin);
+                }
+
+                ret = of_property_read_u32(np,
+                        "echo-active-ms",
+                        &value);
+                if (ret) {
+                        dev_err(&pdev->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(&pdev->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 +192,11 @@ static int pps_gpio_probe(struct platform_device *pdev)
         /* GPIO setup */
         if (pdata) {
                 data->gpio_pin = pdata->gpio_pin;
+                data->echo_pin = pdata->echo_pin;
 
                 data->assert_falling_edge = pdata->assert_falling_edge;
                 data->capture_clear = pdata->capture_clear;
+                data->echo_active_ms = pdata->echo_active_ms;
         } else {
                 ret = pps_gpio_setup(pdev);
                 if (ret)
@@ -148,6 +220,11 @@ static int pps_gpio_probe(struct platform_device *pdev)
         data->info.owner = THIS_MODULE;
         snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
                  pdev->name, pdev->id);
+        if (data->echo_pin) {
+                data->info.echo = pps_gpio_echo;
+                data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
+                timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
+        }
 
         /* register PPS source */
         pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
@@ -180,6 +257,11 @@ static int pps_gpio_remove(struct platform_device *pdev)
         struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 
         pps_unregister_source(data->pps);
+        if (data->echo_pin) {
+                del_timer_sync(&data->echo_timer);
+                /* reset echo pin in any case */
+                gpiod_set_value(data->echo_pin, 0);
+        }
         dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
         return 0;
 }
@@ -204,4 +286,4 @@ MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 MODULE_LICENSE("GPL");
-MODULE_VERSION("1.1.0");
+MODULE_VERSION("1.2.0");
diff --git a/include/linux/pps-gpio.h b/include/linux/pps-gpio.h
index f028d2cda6f5..44171e6b7197 100644
--- a/include/linux/pps-gpio.h
+++ b/include/linux/pps-gpio.h
@@ -24,8 +24,10 @@
 
 struct pps_gpio_platform_data {
         struct gpio_desc *gpio_pin;
+        struct gpio_desc *echo_pin;
         bool assert_falling_edge;
         bool capture_clear;
+        unsigned int echo_active_ms;
 };
 
 #endif /* _PPS_GPIO_H */