From: Bartosz Golaszewski <bartekgola@gmail.com>
Date: Wed, 11 Jan 2017 11:57:39 +0000 (+0100)
Subject: core: implement simple event monitoring
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=571b1b06a5a716e028054a53c3f5ea49719557e4;p=qemu-gpiodev%2Flibgpiod.git

core: implement simple event monitoring

Add a function and corresponding data structures for simple event
monitoring.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
---

diff --git a/core.c b/core.c
index 7602531..e50a2e6 100644
--- a/core.c
+++ b/core.c
@@ -242,6 +242,66 @@ int gpiod_simple_set_value(const char *device, unsigned int offset, int value,
 	return 0;
 }
 
+int gpiod_simple_event_loop(const char *device, unsigned int offset,
+			    bool active_low, struct timespec *timeout,
+			    gpiod_event_cb callback, void *cbdata)
+{
+	struct gpiod_line_evreq_config config;
+	struct gpiod_line_event event;
+	struct gpiod_chip *chip;
+	struct gpiod_line *line;
+	int status, evtype;
+
+	memset(&config, 0, sizeof(config));
+	config.consumer = libgpiod_consumer;
+	config.event_type = GPIOD_EVENT_BOTH_EDGES;
+	config.active_state = active_low ? GPIOD_ACTIVE_STATE_LOW
+					 : GPIOD_ACTIVE_STATE_HIGH;
+
+	chip = gpiod_chip_open_lookup(device);
+	if (!chip)
+		return -1;
+
+	line = gpiod_chip_get_line(chip, offset);
+	if (!line) {
+		gpiod_chip_close(chip);
+		return -1;
+	}
+
+	status = gpiod_line_event_request(line, &config);
+	if (status < 0) {
+		gpiod_chip_close(chip);
+		return -1;
+	}
+
+	for (;;) {
+		status = gpiod_line_event_wait(line, timeout);
+		if (status < 0) {
+			goto out;
+		} else if (status == 0) {
+			evtype = GPIOD_EVENT_CB_TIMEOUT;
+		} else {
+			status = gpiod_line_event_read(line, &event);
+			if (status < 0)
+				goto out;
+
+			evtype = event.event_type == GPIOD_EVENT_RISING_EDGE
+						? GPIOD_EVENT_CB_RISING_EDGE
+						: GPIOD_EVENT_CB_FALLING_EDGE;
+		}
+
+		status = callback(evtype, &event.ts, cbdata);
+		if (status == GPIOD_EVENT_CB_STOP)
+			goto out;
+	}
+
+out:
+	gpiod_line_event_release(line);
+	gpiod_chip_close(chip);
+
+	return status;
+}
+
 static void line_set_offset(struct gpiod_line *line, unsigned int offset)
 {
 	line->info.line_offset = offset;
diff --git a/gpiod.h b/gpiod.h
index d8e9789..fca5e0b 100644
--- a/gpiod.h
+++ b/gpiod.h
@@ -145,6 +145,48 @@ int gpiod_simple_set_value(const char *device, unsigned int offset,
 			   int value, bool active_low, void (*cb)(void *),
 			   void *data) GPIOD_API;
 
+/**
+ * @brief Event types that can be passed to the simple event callback.
+ */
+enum {
+	GPIOD_EVENT_CB_TIMEOUT,
+	/**< Waiting for events timed out. */
+	GPIOD_EVENT_CB_RISING_EDGE,
+	/**< Rising edge event occured. */
+	GPIOD_EVENT_CB_FALLING_EDGE,
+	/**< Falling edge event occured. */
+};
+
+/**
+ * @brief Return status values that the simple event callback can return.
+ */
+enum {
+	GPIOD_EVENT_CB_OK = 0,
+	/**< Continue processing events. */
+	GPIOD_EVENT_CB_STOP,
+	/**< Stop processing events. */
+};
+
+/**
+ * @brief Simple event callack signature.
+ */
+typedef int (*gpiod_event_cb)(int, const struct timespec *, void *);
+
+/**
+ * @brief Wait for events on a single GPIO line.
+ * @param device Name, path or number of the gpiochip.
+ * @param offset GPIO line offset on the chip.
+ * @param active_low The active state of this line - true if low.
+ * @param timeout Maximum wait time for each iteration.
+ * @param callback Callback function to call on event occurence.
+ * @param cbdata User data passed to the callback.
+ * @return 0 no errors were encountered, -1 if an error occured.
+ *
+ */
+int gpiod_simple_event_loop(const char *device, unsigned int offset,
+			    bool active_low, struct timespec *timeout,
+			    gpiod_event_cb callback, void *cbdata) GPIOD_API;
+
 /**
  * @}
  *