leds: Add the actpwr trigger

The actpwr trigger is a meta trigger that cycles between an inverted
mmc0 and default-on. It is written in a way that could fairly easily
be generalised to support alternative sets of source triggers.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index dd9e5ab..6100c96 100644 (file)
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -162,4 +162,15 @@ config LEDS_TRIGGER_TTY
 
          When build as a module this driver will be called ledtrig-tty.
 
+config LEDS_TRIGGER_ACTPWR
+       tristate "ACT/PWR Input Trigger"
+       depends on LEDS_TRIGGERS
+       help
+         This trigger is intended for platforms that have one software-
+         controllable LED and no dedicated activity or power LEDs, hence the
+         need to make the one LED perform both functions. It cycles between
+         default-on and an inverted mmc0 every 500ms, guaranteeing that it is
+         on for at least half of the time.
+         If unsure, say N.
+
 endif # LEDS_TRIGGERS

diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
index 5b6bc14..8bcb576 100644 (file)
--- a/drivers/leds/trigger/Makefile
+++ b/drivers/leds/trigger/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_LEDS_TRIGGER_NETDEV)     += ledtrig-netdev.o
 obj-$(CONFIG_LEDS_TRIGGER_PATTERN)     += ledtrig-pattern.o
 obj-$(CONFIG_LEDS_TRIGGER_AUDIO)       += ledtrig-audio.o
 obj-$(CONFIG_LEDS_TRIGGER_TTY)         += ledtrig-tty.o
+obj-$(CONFIG_LEDS_TRIGGER_ACTPWR)      += ledtrig-actpwr.o

diff --git a/drivers/leds/trigger/ledtrig-actpwr.c b/drivers/leds/trigger/ledtrig-actpwr.c
new file mode 100644 (file)
index 0000000..1a52107
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-actpwr.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Activity/power trigger
+ *
+ * Copyright (C) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * Based on Atsushi Nemoto's ledtrig-heartbeat.c, although there may be
+ * nothing left of the original now.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/leds.h>
+#include "../leds.h"
+
+enum {
+       TRIG_ACT,
+       TRIG_PWR,
+
+       TRIG_COUNT
+};
+
+struct actpwr_trig_src {
+       const char *name;
+       int interval;
+       bool invert;
+};
+
+struct actpwr_vled {
+       struct led_classdev cdev;
+       struct actpwr_trig_data *parent;
+       enum led_brightness value;
+       unsigned int interval;
+       bool invert;
+};
+
+struct actpwr_trig_data {
+       struct led_trigger trig;
+       struct actpwr_vled virt_leds[TRIG_COUNT];
+       struct actpwr_vled *active;
+       struct timer_list timer;
+       int next_active;
+};
+
+static int actpwr_trig_activate(struct led_classdev *led_cdev);
+static void actpwr_trig_deactivate(struct led_classdev *led_cdev);
+
+static const struct actpwr_trig_src actpwr_trig_sources[TRIG_COUNT] = {
+       [TRIG_ACT] = { "mmc0", 500, true },
+       [TRIG_PWR] = { "default-on", 500, false },
+};
+
+static struct actpwr_trig_data actpwr_data = {
+       {
+               .name     = "actpwr",
+               .activate = actpwr_trig_activate,
+               .deactivate = actpwr_trig_deactivate,
+       }
+};
+
+static void actpwr_brightness_set(struct led_classdev *led_cdev,
+                                 enum led_brightness value)
+{
+       struct actpwr_vled *vled = container_of(led_cdev, struct actpwr_vled,
+                                              cdev);
+       struct actpwr_trig_data *trig = vled->parent;
+
+       if (vled->invert)
+               value = !value;
+       vled->value = value;
+
+       if (vled == trig->active)
+               led_trigger_event(&trig->trig, value);
+}
+
+static int actpwr_brightness_set_blocking(struct led_classdev *led_cdev,
+                                         enum led_brightness value)
+{
+       actpwr_brightness_set(led_cdev, value);
+       return 0;
+}
+
+static enum led_brightness actpwr_brightness_get(struct led_classdev *led_cdev)
+{
+       struct actpwr_vled *vled = container_of(led_cdev, struct actpwr_vled,
+                                             cdev);
+
+       return vled->value;
+}
+
+static void actpwr_trig_cycle(struct timer_list *t)
+{
+       struct actpwr_trig_data *trig  = &actpwr_data;
+       struct actpwr_vled *active;
+
+       active = &trig->virt_leds[trig->next_active];
+       trig->active = active;
+       trig->next_active = (trig->next_active + 1) % TRIG_COUNT;
+
+       led_trigger_event(&trig->trig, active->value);
+
+       mod_timer(&trig->timer, jiffies + msecs_to_jiffies(active->interval));
+}
+
+static int actpwr_trig_activate(struct led_classdev *led_cdev)
+{
+       struct actpwr_trig_data *trig  = &actpwr_data;
+
+       /* Start the timer if this is the first LED */
+       if (!trig->active)
+               actpwr_trig_cycle(&trig->timer);
+       else
+               led_set_brightness_nosleep(led_cdev, trig->active->value);
+
+       return 0;
+}
+
+static void actpwr_trig_deactivate(struct led_classdev *led_cdev)
+{
+       struct actpwr_trig_data *trig  = &actpwr_data;
+
+       if (list_empty(&trig->trig.led_cdevs)) {
+               del_timer_sync(&trig->timer);
+               trig->active = NULL;
+       }
+}
+
+static int __init actpwr_trig_init(void)
+{
+       struct actpwr_trig_data *trig  = &actpwr_data;
+       int ret = 0;
+       int i;
+
+       timer_setup(&trig->timer, actpwr_trig_cycle, 0);
+
+       /* Register one "LED" for each source trigger */
+       for (i = 0; i < TRIG_COUNT; i++)
+       {
+               struct actpwr_vled *vled = &trig->virt_leds[i];
+               struct led_classdev *cdev = &vled->cdev;
+               const struct actpwr_trig_src *src = &actpwr_trig_sources[i];
+
+               vled->parent = trig;
+               vled->interval = src->interval;
+               vled->invert = src->invert;
+               cdev->name = src->name;
+               cdev->brightness_set = actpwr_brightness_set;
+               cdev->brightness_set_blocking = actpwr_brightness_set_blocking;
+               cdev->brightness_get = actpwr_brightness_get;
+               cdev->default_trigger = src->name;
+               ret = led_classdev_register(NULL, cdev);
+               if (ret)
+                       goto error_classdev;
+       }
+
+       ret = led_trigger_register(&trig->trig);
+       if (ret)
+               goto error_classdev;
+
+       return 0;
+
+error_classdev:
+       while (i > 0)
+       {
+               i--;
+               led_classdev_unregister(&trig->virt_leds[i].cdev);
+       }
+
+       return ret;
+}
+
+static void __exit actpwr_trig_exit(void)
+{
+       int i;
+
+       led_trigger_unregister(&actpwr_data.trig);
+       for (i = 0; i < TRIG_COUNT; i++)
+       {
+               led_classdev_unregister(&actpwr_data.virt_leds[i].cdev);
+       }
+}
+
+module_init(actpwr_trig_init);
+module_exit(actpwr_trig_exit);
+
+MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.com>");
+MODULE_DESCRIPTION("ACT/PWR LED trigger");
+MODULE_LICENSE("GPL v2");