@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ *	Block device LED triggers
+ *
+ *	Copyright 2021 Ian Pilcher <arequipeno@gmail.com>
+ */
+
+#include <linux/leds.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+
+/* Default blink time & polling interval (milliseconds) */
+#define LEDTRIG_BLKDEV_BLINK_MSEC	75
+#define LEDTRIG_BLKDEV_INTERVAL		100
+
+/* Minimum VALUE for interval or blink_time */
+#define LEDTRIG_BLKDEV_MIN_TIME		25
+
+enum ledtrig_blkdev_mode {
+	LEDTRIG_BLKDEV_MODE_RO	= 0,	/* blink for reads */
+	LEDTRIG_BLKDEV_MODE_WO	= 1,	/* blink for writes */
+	LEDTRIG_BLKDEV_MODE_RW	= 2	/* blink for reads and writes */
+};
+
+/* Trigger-specific info about a block device */
+struct ledtrig_blkdev_disk {
+	struct gendisk		*gd;
+	struct kobject		*dir;
+	struct hlist_head	leds;
+	unsigned long		read_ios;
+	unsigned long		write_ios;
+	unsigned int		generation;
+	bool			read_act;
+	bool			write_act;
+};
+
+/* For many-to-many relationships between "disks" (block devices) and LEDs */
+struct ledtrig_blkdev_link {
+	struct hlist_node		disk_leds_node;
+	struct hlist_node		led_disks_node;
+	struct ledtrig_blkdev_disk	*disk;
+	struct ledtrig_blkdev_led	*led;
+};
+
+/* Every LED associated with the blkdev trigger gets one of these */
+struct ledtrig_blkdev_led {
+	struct kobject			*dir;		/* block_devices dir */
+	struct led_classdev		*led_dev;
+	unsigned int			blink_msec;
+	struct hlist_head		disks;		/* linked block devs */
+	struct hlist_node		leds_node;
+	enum ledtrig_blkdev_mode	mode;
+};
+
+/* All LEDs associated with the trigger */
+static HLIST_HEAD(ledtrig_blkdev_leds);
+
+/* Must hold when changing trigger/LED/device associations */
+static DEFINE_MUTEX(ledtrig_blkdev_mutex);
+
+/* Total number of device-to-LED associations */
+static unsigned int ledtrig_blkdev_count;
+
+/* How often to check for drive activity - in jiffies */
+static unsigned int ledtrig_blkdev_interval;