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leds: Add the "input" trigger, for pwr_led

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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
This commit is contained in:
Phil Elwell
2015-02-06 13:50:57 +00:00
committed by Dom Cobley
parent 8fea5a2937
commit 6ea0ab8255
5 changed files with 82 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/leds/leds-gpio.c
View File

@@ -47,8 +47,15 @@ static void gpio_led_set(struct led_classdev *led_cdev,
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 led_classdev *led_cdev,
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 gpio_led *template,
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)

7
drivers/leds/trigger/Kconfig
View File

@@ -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

1
drivers/leds/trigger/Makefile
View File

@@ -11,6 +11,7 @@ obj-$(CONFIG_LEDS_TRIGGER_ACTIVITY) += ledtrig-activity.o
obj-$(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

55
drivers/leds/trigger/ledtrig-input.c Normal file
View File

@@ -0,0 +1,55 @@
/*
* Set LED GPIO to Input "Trigger"
*
* Copyright 2015 Phil Elwell <phil@raspberrypi.org>
*
* 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 <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/leds.h>
#include <linux/gpio.h>
#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 <phil@raspberrypi.org>");
MODULE_DESCRIPTION("Set LED GPIO to Input \"trigger\"");
MODULE_LICENSE("GPL");

3
include/linux/leds.h
View File

@@ -85,6 +85,9 @@ 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;