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168 lines
5.6 KiB
168 lines
5.6 KiB
![]()
6 years ago
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From 55006c315659a66183d5513c1b441651a3c9a5fd Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 6 Feb 2015 13:50:57 +0000
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Subject: [PATCH 055/454] BCM270x_DT: Add pwr_led, and the required "input"
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trigger
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The "input" trigger makes the associated GPIO an input. This is to support
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the Raspberry Pi PWR LED, which is driven by external hardware in normal use.
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N.B. pwr_led is not available on Model A or B boards.
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leds-gpio: Implement the brightness_get method
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The power LED uses some clever logic that means it is driven
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by a voltage measuring circuit when configured as input, otherwise
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it is driven by the GPIO output value. This patch wires up the
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brightness_get method for leds-gpio so that user-space can monitor
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the LED value via /sys/class/gpio/led1/brightness. Using the input
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trigger this returns an indication of the system power health,
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otherwise it is just whatever value the trigger has written most
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recently.
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See: https://github.com/raspberrypi/linux/issues/1064
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---
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drivers/leds/leds-gpio.c | 17 ++++++++-
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drivers/leds/trigger/Kconfig | 7 ++++
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drivers/leds/trigger/Makefile | 1 +
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drivers/leds/trigger/ledtrig-input.c | 54 ++++++++++++++++++++++++++++
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include/linux/leds.h | 3 ++
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5 files changed, 81 insertions(+), 1 deletion(-)
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create mode 100644 drivers/leds/trigger/ledtrig-input.c
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--- a/drivers/leds/leds-gpio.c
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+++ b/drivers/leds/leds-gpio.c
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@@ -50,8 +50,15 @@ static void gpio_led_set(struct led_clas
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led_dat->platform_gpio_blink_set(led_dat->gpiod, level,
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NULL, NULL);
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led_dat->blinking = 0;
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+ } else if (led_dat->cdev.flags & SET_GPIO_INPUT) {
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+ gpiod_direction_input(led_dat->gpiod);
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+ led_dat->cdev.flags &= ~SET_GPIO_INPUT;
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+ } else if (led_dat->cdev.flags & SET_GPIO_OUTPUT) {
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+ gpiod_direction_output(led_dat->gpiod, level);
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+ led_dat->cdev.flags &= ~SET_GPIO_OUTPUT;
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} else {
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- if (led_dat->can_sleep)
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+ if (led_dat->can_sleep ||
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+ (led_dat->cdev.flags & (SET_GPIO_INPUT | SET_GPIO_OUTPUT) ))
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gpiod_set_value_cansleep(led_dat->gpiod, level);
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else
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gpiod_set_value(led_dat->gpiod, level);
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@@ -65,6 +72,13 @@ static int gpio_led_set_blocking(struct
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return 0;
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}
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+static enum led_brightness gpio_led_get(struct led_classdev *led_cdev)
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+{
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+ struct gpio_led_data *led_dat =
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+ container_of(led_cdev, struct gpio_led_data, cdev);
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+ return gpiod_get_value_cansleep(led_dat->gpiod) ? LED_FULL : LED_OFF;
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+}
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+
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static int gpio_blink_set(struct led_classdev *led_cdev,
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unsigned long *delay_on, unsigned long *delay_off)
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{
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@@ -122,6 +136,7 @@ static int create_gpio_led(const struct
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led_dat->platform_gpio_blink_set = blink_set;
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led_dat->cdev.blink_set = gpio_blink_set;
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}
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+ led_dat->cdev.brightness_get = gpio_led_get;
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if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) {
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state = gpiod_get_value_cansleep(led_dat->gpiod);
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if (state < 0)
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--- a/drivers/leds/trigger/Kconfig
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+++ b/drivers/leds/trigger/Kconfig
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@@ -116,6 +116,13 @@ config LEDS_TRIGGER_CAMERA
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This enables direct flash/torch on/off by the driver, kernel space.
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If unsure, say Y.
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+config LEDS_TRIGGER_INPUT
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+ tristate "LED Input Trigger"
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+ depends on LEDS_TRIGGERS
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+ help
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+ This allows the GPIOs assigned to be LEDs to be initialised to inputs.
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+ If unsure, say Y.
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+
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config LEDS_TRIGGER_PANIC
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bool "LED Panic Trigger"
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depends on LEDS_TRIGGERS
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--- a/drivers/leds/trigger/Makefile
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+++ b/drivers/leds/trigger/Makefile
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@@ -10,5 +10,6 @@ obj-$(CONFIG_LEDS_TRIGGER_CPU) += ledtr
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obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
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obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o
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obj-$(CONFIG_LEDS_TRIGGER_CAMERA) += ledtrig-camera.o
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+obj-$(CONFIG_LEDS_TRIGGER_INPUT) += ledtrig-input.o
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obj-$(CONFIG_LEDS_TRIGGER_PANIC) += ledtrig-panic.o
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obj-$(CONFIG_LEDS_TRIGGER_NETDEV) += ledtrig-netdev.o
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--- /dev/null
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+++ b/drivers/leds/trigger/ledtrig-input.c
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@@ -0,0 +1,54 @@
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+/*
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+ * Set LED GPIO to Input "Trigger"
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+ *
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+ * Copyright 2015 Phil Elwell <phil@raspberrypi.org>
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+ *
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+ * Based on Nick Forbes's ledtrig-default-on.c.
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ *
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/kernel.h>
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+#include <linux/init.h>
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+#include <linux/leds.h>
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+#include <linux/gpio.h>
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+#include "../leds.h"
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+
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+static void input_trig_activate(struct led_classdev *led_cdev)
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+{
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+ led_cdev->flags |= SET_GPIO_INPUT;
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+ led_set_brightness(led_cdev, 0);
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+}
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+
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+static void input_trig_deactivate(struct led_classdev *led_cdev)
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+{
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+ led_cdev->flags |= SET_GPIO_OUTPUT;
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+ led_set_brightness(led_cdev, 0);
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+}
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+
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+static struct led_trigger input_led_trigger = {
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+ .name = "input",
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+ .activate = input_trig_activate,
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+ .deactivate = input_trig_deactivate,
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+};
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+
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+static int __init input_trig_init(void)
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+{
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+ return led_trigger_register(&input_led_trigger);
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+}
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+
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+static void __exit input_trig_exit(void)
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+{
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+ led_trigger_unregister(&input_led_trigger);
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+}
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+
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+module_init(input_trig_init);
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+module_exit(input_trig_exit);
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+
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+MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.org>");
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+MODULE_DESCRIPTION("Set LED GPIO to Input \"trigger\"");
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+MODULE_LICENSE("GPL");
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--- a/include/linux/leds.h
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+++ b/include/linux/leds.h
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@@ -50,6 +50,9 @@ struct led_classdev {
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#define LED_PANIC_INDICATOR (1 << 20)
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#define LED_BRIGHT_HW_CHANGED (1 << 21)
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#define LED_RETAIN_AT_SHUTDOWN (1 << 22)
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+ /* Additions for Raspberry Pi PWR LED */
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+#define SET_GPIO_INPUT (1 << 30)
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+#define SET_GPIO_OUTPUT (1 << 31)
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/* set_brightness_work / blink_timer flags, atomic, private. */
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unsigned long work_flags;
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