From 95a128d3e27f80940acd7f5d657405a50b2bc830 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Fri, 6 Feb 2015 13:50:57 +0000 Subject: [PATCH] leds: Add the "input" trigger, for pwr_led The "input" trigger makes the associated GPIO an input. This is to support the Raspberry Pi PWR LED, which is driven by external hardware in normal use. N.B. pwr_led is not available on Model A or B boards. leds-gpio: Implement the brightness_get method The power LED uses some clever logic that means it is driven by a voltage measuring circuit when configured as input, otherwise it is driven by the GPIO output value. This patch wires up the brightness_get method for leds-gpio so that user-space can monitor the LED value via /sys/class/gpio/led1/brightness. Using the input trigger this returns an indication of the system power health, otherwise it is just whatever value the trigger has written most recently. See: https://github.com/raspberrypi/linux/issues/1064 --- drivers/leds/leds-gpio.c | 17 ++++++++- drivers/leds/trigger/Kconfig | 7 ++++ drivers/leds/trigger/Makefile | 1 + drivers/leds/trigger/ledtrig-input.c | 55 ++++++++++++++++++++++++++++ include/linux/leds.h | 3 ++ 5 files changed, 82 insertions(+), 1 deletion(-) create mode 100644 drivers/leds/trigger/ledtrig-input.c --- a/drivers/leds/leds-gpio.c +++ b/drivers/leds/leds-gpio.c @@ -47,8 +47,15 @@ static void gpio_led_set(struct led_clas led_dat->platform_gpio_blink_set(led_dat->gpiod, level, NULL, NULL); led_dat->blinking = 0; + } else if (led_dat->cdev.flags & SET_GPIO_INPUT) { + gpiod_direction_input(led_dat->gpiod); + led_dat->cdev.flags &= ~SET_GPIO_INPUT; + } else if (led_dat->cdev.flags & SET_GPIO_OUTPUT) { + gpiod_direction_output(led_dat->gpiod, level); + led_dat->cdev.flags &= ~SET_GPIO_OUTPUT; } else { - if (led_dat->can_sleep) + if (led_dat->can_sleep || + (led_dat->cdev.flags & (SET_GPIO_INPUT | SET_GPIO_OUTPUT) )) gpiod_set_value_cansleep(led_dat->gpiod, level); else gpiod_set_value(led_dat->gpiod, level); @@ -62,6 +69,13 @@ static int gpio_led_set_blocking(struct return 0; } +static enum led_brightness gpio_led_get(struct led_classdev *led_cdev) +{ + struct gpio_led_data *led_dat = + container_of(led_cdev, struct gpio_led_data, cdev); + return gpiod_get_value_cansleep(led_dat->gpiod) ? LED_FULL : LED_OFF; +} + static int gpio_blink_set(struct led_classdev *led_cdev, unsigned long *delay_on, unsigned long *delay_off) { @@ -90,6 +104,7 @@ static int create_gpio_led(const struct led_dat->platform_gpio_blink_set = blink_set; led_dat->cdev.blink_set = gpio_blink_set; } + led_dat->cdev.brightness_get = gpio_led_get; if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) { state = gpiod_get_value_cansleep(led_dat->gpiod); if (state < 0) --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -115,6 +115,13 @@ config LEDS_TRIGGER_CAMERA This enables direct flash/torch on/off by the driver, kernel space. If unsure, say Y. +config LEDS_TRIGGER_INPUT + tristate "LED Input Trigger" + depends on LEDS_TRIGGERS + help + This allows the GPIOs assigned to be LEDs to be initialised to inputs. + If unsure, say Y. + config LEDS_TRIGGER_PANIC bool "LED Panic Trigger" help --- a/drivers/leds/trigger/Makefile +++ b/drivers/leds/trigger/Makefile @@ -11,6 +11,7 @@ obj-$(CONFIG_LEDS_TRIGGER_ACTIVITY) += l obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o obj-$(CONFIG_LEDS_TRIGGER_CAMERA) += ledtrig-camera.o +obj-$(CONFIG_LEDS_TRIGGER_INPUT) += ledtrig-input.o obj-$(CONFIG_LEDS_TRIGGER_PANIC) += ledtrig-panic.o obj-$(CONFIG_LEDS_TRIGGER_NETDEV) += ledtrig-netdev.o obj-$(CONFIG_LEDS_TRIGGER_PATTERN) += ledtrig-pattern.o --- /dev/null +++ b/drivers/leds/trigger/ledtrig-input.c @@ -0,0 +1,55 @@ +/* + * Set LED GPIO to Input "Trigger" + * + * Copyright 2015 Phil Elwell + * + * Based on Nick Forbes's ledtrig-default-on.c. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include +#include +#include +#include +#include +#include "../leds.h" + +static int input_trig_activate(struct led_classdev *led_cdev) +{ + led_cdev->flags |= SET_GPIO_INPUT; + led_set_brightness(led_cdev, 0); + return 0; +} + +static void input_trig_deactivate(struct led_classdev *led_cdev) +{ + led_cdev->flags |= SET_GPIO_OUTPUT; + led_set_brightness(led_cdev, 0); +} + +static struct led_trigger input_led_trigger = { + .name = "input", + .activate = input_trig_activate, + .deactivate = input_trig_deactivate, +}; + +static int __init input_trig_init(void) +{ + return led_trigger_register(&input_led_trigger); +} + +static void __exit input_trig_exit(void) +{ + led_trigger_unregister(&input_led_trigger); +} + +module_init(input_trig_init); +module_exit(input_trig_exit); + +MODULE_AUTHOR("Phil Elwell "); +MODULE_DESCRIPTION("Set LED GPIO to Input \"trigger\""); +MODULE_LICENSE("GPL"); --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -95,6 +95,9 @@ struct led_classdev { #define LED_BRIGHT_HW_CHANGED BIT(21) #define LED_RETAIN_AT_SHUTDOWN BIT(22) #define LED_INIT_DEFAULT_TRIGGER BIT(23) + /* Additions for Raspberry Pi PWR LED */ +#define SET_GPIO_INPUT BIT(30) +#define SET_GPIO_OUTPUT BIT(31) /* set_brightness_work / blink_timer flags, atomic, private. */ unsigned long work_flags;