1 From 8a9552813613d4f2d57e7ef97e4e43279603bf85 Mon Sep 17 00:00:00 2001
2 From: Phil Elwell <phil@raspberrypi.org>
3 Date: Fri, 6 Feb 2015 13:50:57 +0000
4 Subject: [PATCH] leds: Add the "input" trigger, for pwr_led
6 The "input" trigger makes the associated GPIO an input. This is to support
7 the Raspberry Pi PWR LED, which is driven by external hardware in normal use.
9 N.B. pwr_led is not available on Model A or B boards.
11 leds-gpio: Implement the brightness_get method
13 The power LED uses some clever logic that means it is driven
14 by a voltage measuring circuit when configured as input, otherwise
15 it is driven by the GPIO output value. This patch wires up the
16 brightness_get method for leds-gpio so that user-space can monitor
17 the LED value via /sys/class/gpio/led1/brightness. Using the input
18 trigger this returns an indication of the system power health,
19 otherwise it is just whatever value the trigger has written most
22 See: https://github.com/raspberrypi/linux/issues/1064
24 drivers/leds/leds-gpio.c | 17 ++++++++-
25 drivers/leds/trigger/Kconfig | 7 ++++
26 drivers/leds/trigger/Makefile | 1 +
27 drivers/leds/trigger/ledtrig-input.c | 55 ++++++++++++++++++++++++++++
28 include/linux/leds.h | 3 ++
29 5 files changed, 82 insertions(+), 1 deletion(-)
30 create mode 100644 drivers/leds/trigger/ledtrig-input.c
32 --- a/drivers/leds/leds-gpio.c
33 +++ b/drivers/leds/leds-gpio.c
34 @@ -47,8 +47,15 @@ static void gpio_led_set(struct led_clas
35 led_dat->platform_gpio_blink_set(led_dat->gpiod, level,
37 led_dat->blinking = 0;
38 + } else if (led_dat->cdev.flags & SET_GPIO_INPUT) {
39 + gpiod_direction_input(led_dat->gpiod);
40 + led_dat->cdev.flags &= ~SET_GPIO_INPUT;
41 + } else if (led_dat->cdev.flags & SET_GPIO_OUTPUT) {
42 + gpiod_direction_output(led_dat->gpiod, level);
43 + led_dat->cdev.flags &= ~SET_GPIO_OUTPUT;
45 - if (led_dat->can_sleep)
46 + if (led_dat->can_sleep ||
47 + (led_dat->cdev.flags & (SET_GPIO_INPUT | SET_GPIO_OUTPUT) ))
48 gpiod_set_value_cansleep(led_dat->gpiod, level);
50 gpiod_set_value(led_dat->gpiod, level);
51 @@ -62,6 +69,13 @@ static int gpio_led_set_blocking(struct
55 +static enum led_brightness gpio_led_get(struct led_classdev *led_cdev)
57 + struct gpio_led_data *led_dat =
58 + container_of(led_cdev, struct gpio_led_data, cdev);
59 + return gpiod_get_value_cansleep(led_dat->gpiod) ? LED_FULL : LED_OFF;
62 static int gpio_blink_set(struct led_classdev *led_cdev,
63 unsigned long *delay_on, unsigned long *delay_off)
65 @@ -90,6 +104,7 @@ static int create_gpio_led(const struct
66 led_dat->platform_gpio_blink_set = blink_set;
67 led_dat->cdev.blink_set = gpio_blink_set;
69 + led_dat->cdev.brightness_get = gpio_led_get;
70 if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) {
71 state = gpiod_get_value_cansleep(led_dat->gpiod);
73 --- a/drivers/leds/trigger/Kconfig
74 +++ b/drivers/leds/trigger/Kconfig
75 @@ -114,6 +114,13 @@ config LEDS_TRIGGER_CAMERA
76 This enables direct flash/torch on/off by the driver, kernel space.
79 +config LEDS_TRIGGER_INPUT
80 + tristate "LED Input Trigger"
81 + depends on LEDS_TRIGGERS
83 + This allows the GPIOs assigned to be LEDs to be initialised to inputs.
86 config LEDS_TRIGGER_PANIC
87 bool "LED Panic Trigger"
89 --- a/drivers/leds/trigger/Makefile
90 +++ b/drivers/leds/trigger/Makefile
91 @@ -11,6 +11,7 @@ obj-$(CONFIG_LEDS_TRIGGER_ACTIVITY) += l
92 obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
93 obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o
94 obj-$(CONFIG_LEDS_TRIGGER_CAMERA) += ledtrig-camera.o
95 +obj-$(CONFIG_LEDS_TRIGGER_INPUT) += ledtrig-input.o
96 obj-$(CONFIG_LEDS_TRIGGER_PANIC) += ledtrig-panic.o
97 obj-$(CONFIG_LEDS_TRIGGER_NETDEV) += ledtrig-netdev.o
98 obj-$(CONFIG_LEDS_TRIGGER_PATTERN) += ledtrig-pattern.o
100 +++ b/drivers/leds/trigger/ledtrig-input.c
103 + * Set LED GPIO to Input "Trigger"
105 + * Copyright 2015 Phil Elwell <phil@raspberrypi.org>
107 + * Based on Nick Forbes's ledtrig-default-on.c.
109 + * This program is free software; you can redistribute it and/or modify
110 + * it under the terms of the GNU General Public License version 2 as
111 + * published by the Free Software Foundation.
115 +#include <linux/module.h>
116 +#include <linux/kernel.h>
117 +#include <linux/init.h>
118 +#include <linux/leds.h>
119 +#include <linux/gpio.h>
120 +#include "../leds.h"
122 +static int input_trig_activate(struct led_classdev *led_cdev)
124 + led_cdev->flags |= SET_GPIO_INPUT;
125 + led_set_brightness(led_cdev, 0);
129 +static void input_trig_deactivate(struct led_classdev *led_cdev)
131 + led_cdev->flags |= SET_GPIO_OUTPUT;
132 + led_set_brightness(led_cdev, 0);
135 +static struct led_trigger input_led_trigger = {
137 + .activate = input_trig_activate,
138 + .deactivate = input_trig_deactivate,
141 +static int __init input_trig_init(void)
143 + return led_trigger_register(&input_led_trigger);
146 +static void __exit input_trig_exit(void)
148 + led_trigger_unregister(&input_led_trigger);
151 +module_init(input_trig_init);
152 +module_exit(input_trig_exit);
154 +MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.org>");
155 +MODULE_DESCRIPTION("Set LED GPIO to Input \"trigger\"");
156 +MODULE_LICENSE("GPL");
157 --- a/include/linux/leds.h
158 +++ b/include/linux/leds.h
159 @@ -85,6 +85,9 @@ struct led_classdev {
160 #define LED_BRIGHT_HW_CHANGED BIT(21)
161 #define LED_RETAIN_AT_SHUTDOWN BIT(22)
162 #define LED_INIT_DEFAULT_TRIGGER BIT(23)
163 + /* Additions for Raspberry Pi PWR LED */
164 +#define SET_GPIO_INPUT BIT(30)
165 +#define SET_GPIO_OUTPUT BIT(31)
167 /* set_brightness_work / blink_timer flags, atomic, private. */
168 unsigned long work_flags;