From 883e395b2b07ab04f8fe57ac91e63e71dde5d4f6 Mon Sep 17 00:00:00 2001
From: John Klug <john.klug@multitech.com>
Date: Tue, 10 Aug 2021 18:21:34 -0500
Subject: Add MTRE support

---
 io-module/mts_leds.c | 146 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 io-module/mts_leds.c

(limited to 'io-module/mts_leds.c')

diff --git a/io-module/mts_leds.c b/io-module/mts_leds.c
new file mode 100644
index 0000000..a5cfbbb
--- /dev/null
+++ b/io-module/mts_leds.c
@@ -0,0 +1,146 @@
+/*
+ * Use the code below to control the brightness of the LEDs using
+ * Linux LED framework instead of manipulating gpio pins or i2c registers
+ * directly in the mts-io module.
+ *
+ * Usage:
+ *
+ * # associate a mts-io sysfs entry with the specific LEDs
+ * echo led-sig1 > /sys/class/leds/pca955x:0/trigger
+ * echo led-sig2 > /sys/class/leds/pca955x:1/trigger
+ * echo led-sig3 > /sys/class/leds/pca955x:2/trigger
+ *
+ * # change the brightness
+ * echo 1 > /sys/device/platform/mts-io/led-sig1
+ * echo 1 > /sys/device/platform/mts-io/led-sig2
+ *
+ */
+
+struct mts_led {
+	const char label[32];          /* led name exposed by the mts-io kernel module */
+	struct led_trigger *trigger;   /* linux led trigger */
+};
+
+static struct mts_led *mts_leds = NULL;
+
+/*
+ * Find a LED descriptor in mts_leds array by label name
+ */
+static
+struct mts_led *mts_led_by_label(const char *label)
+{
+	struct mts_led *led = mts_leds;
+
+	while (led && *led->label) {
+		if (strcmp(led->label, label) == 0) {
+			return led;
+		}
+		led++;
+	}
+
+	log_error("led with %s label is not found", label);
+
+	return NULL;
+}
+
+/*
+ * Change brightness for Linux LEDs devices
+ */
+static
+void mts_led_set(const struct mts_led *led, int value)
+{
+	enum led_brightness brightness = LED_OFF;
+
+	if (value != 0) brightness = LED_FULL;
+
+	if (led->trigger) {
+		led_trigger_event(led->trigger, brightness);
+	}
+
+	/*
+	 * Note: there are also led_trigger_blink and led_trigger_blink_oneshot
+	 *       functions which can potentially be used
+	 */
+}
+
+/*
+ * Blink one shot
+ */
+static
+void mts_led_blink(const struct mts_led *led,
+                   unsigned long *delay_on, unsigned long *delay_off,  int invert)
+{
+	if (led->trigger) {
+		 led_trigger_blink_oneshot(led->trigger, delay_on, delay_off, invert);
+	}
+}
+
+
+/*
+ * Use the function to get current LED brightness for sysfs entry
+ */
+static
+ssize_t mts_attr_show_led(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", 0);
+}
+
+/*
+ * Use the function to set LED brightness from sysfs entry
+ */
+static
+ssize_t mts_attr_store_led(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int value;
+
+	const struct mts_led *led = mts_led_by_label(attr->attr.name);
+
+	if (!led) {
+		return -ENODEV;
+	}
+
+	if (sscanf(buf, "%i", &value) != 1) {
+		return -EINVAL;
+	}
+
+	mts_led_set(led, value);
+
+	return count;
+}
+
+/*
+ * Register a LED trigger for each LED declared in the mts_leds array
+ * Use in mts-io startup code.
+ */
+static
+void mts_leds_register(void)
+{
+	struct mts_led *led = mts_leds;
+
+	while (led && *led->label) {
+		log_info("Registering %s led trigger", led->label);
+		led_trigger_register_simple(led->label, &led->trigger);
+		led++;
+	}
+}
+
+/*
+ * Unregister all registered LED triggers.
+ * Use in mts-io cleanup code.
+ */
+static
+void mts_leds_unregister(void)
+{
+	struct mts_led *led = mts_leds;
+
+	while (led && *led->label) {
+		log_info("Unregistering %s led trigger", led->label);
+		if (led->trigger) {
+			led_trigger_unregister_simple(led->trigger);
+			led->trigger = NULL;
+		}
+		led++;
+	}
+}
-- 
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