forked from luck/tmp_suning_uos_patched
ed88bae691
There already is a "default-on" trigger but there are problems with it. For one, it's a inefficient way to do it and requires led trigger support to be compiled in. But the real reason is that is produces a glitch on the LED. The GPIO is allocate with the LED *off*, then *later* when the trigger runs it is turned back on. If the LED was already on via the GPIO's reset default or action of the firmware, this produces a glitch where the LED goes from on to off to on. While normally this is fast enough that it wouldn't be noticeable to a human observer, there are still serious problems. One is that there may be something else on the GPIO line, like a hardware alarm or watchdog, that is fast enough to notice the glitch. Another is that the kernel may panic before the LED is turned back on, thus hanging with the LED in the wrong state. This is not just speculation, but actually happened to me with an embedded system that has an LED which should turn off when the kernel finishes booting, which was left in the incorrect state due to a bug in the OF LED binding code. We also let GPIO LEDs get their initial value from whatever the current state of the GPIO line is. On some systems the LEDs are put into some state by the firmware or hardware before Linux boots, and it is desired to have them keep this state which is otherwise unknown to Linux. This requires that the underlying GPIO driver support reading the value of output GPIOs. Some drivers support this and some do not. The platform device binding gains a field in the platform data "default_state" that controls this. There are three constants defined to select from on, off, or keeping the current state. The OpenFirmware binding uses a property named "default-state" that can be set to "on", "off", or "keep". The default if the property isn't present is off. Signed-off-by: Trent Piepho <xyzzy@speakeasy.org> Acked-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Wolfram Sang <w.sang@pengutronix.de> Acked-by: Sean MacLennan <smaclennan@pikatech.com> Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
165 lines
4.3 KiB
C
165 lines
4.3 KiB
C
/*
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* Driver model for leds and led triggers
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*
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* Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
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* Copyright (C) 2005 Richard Purdie <rpurdie@openedhand.com>
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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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#ifndef __LINUX_LEDS_H_INCLUDED
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#define __LINUX_LEDS_H_INCLUDED
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/rwsem.h>
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struct device;
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/*
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* LED Core
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*/
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enum led_brightness {
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LED_OFF = 0,
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LED_HALF = 127,
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LED_FULL = 255,
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};
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struct led_classdev {
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const char *name;
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int brightness;
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int max_brightness;
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int flags;
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/* Lower 16 bits reflect status */
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#define LED_SUSPENDED (1 << 0)
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/* Upper 16 bits reflect control information */
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#define LED_CORE_SUSPENDRESUME (1 << 16)
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/* Set LED brightness level */
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/* Must not sleep, use a workqueue if needed */
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void (*brightness_set)(struct led_classdev *led_cdev,
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enum led_brightness brightness);
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/* Get LED brightness level */
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enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);
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/* Activate hardware accelerated blink, delays are in
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* miliseconds and if none is provided then a sensible default
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* should be chosen. */
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int (*blink_set)(struct led_classdev *led_cdev,
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unsigned long *delay_on,
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unsigned long *delay_off);
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struct device *dev;
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struct list_head node; /* LED Device list */
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const char *default_trigger; /* Trigger to use */
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#ifdef CONFIG_LEDS_TRIGGERS
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/* Protects the trigger data below */
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struct rw_semaphore trigger_lock;
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struct led_trigger *trigger;
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struct list_head trig_list;
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void *trigger_data;
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#endif
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};
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extern int led_classdev_register(struct device *parent,
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struct led_classdev *led_cdev);
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extern void led_classdev_unregister(struct led_classdev *led_cdev);
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extern void led_classdev_suspend(struct led_classdev *led_cdev);
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extern void led_classdev_resume(struct led_classdev *led_cdev);
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/*
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* LED Triggers
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*/
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#ifdef CONFIG_LEDS_TRIGGERS
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#define TRIG_NAME_MAX 50
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struct led_trigger {
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/* Trigger Properties */
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const char *name;
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void (*activate)(struct led_classdev *led_cdev);
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void (*deactivate)(struct led_classdev *led_cdev);
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/* LEDs under control by this trigger (for simple triggers) */
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rwlock_t leddev_list_lock;
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struct list_head led_cdevs;
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/* Link to next registered trigger */
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struct list_head next_trig;
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};
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/* Registration functions for complex triggers */
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extern int led_trigger_register(struct led_trigger *trigger);
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extern void led_trigger_unregister(struct led_trigger *trigger);
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/* Registration functions for simple triggers */
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#define DEFINE_LED_TRIGGER(x) static struct led_trigger *x;
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#define DEFINE_LED_TRIGGER_GLOBAL(x) struct led_trigger *x;
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extern void led_trigger_register_simple(const char *name,
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struct led_trigger **trigger);
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extern void led_trigger_unregister_simple(struct led_trigger *trigger);
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extern void led_trigger_event(struct led_trigger *trigger,
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enum led_brightness event);
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#else
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/* Triggers aren't active - null macros */
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#define DEFINE_LED_TRIGGER(x)
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#define DEFINE_LED_TRIGGER_GLOBAL(x)
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#define led_trigger_register_simple(x, y) do {} while(0)
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#define led_trigger_unregister_simple(x) do {} while(0)
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#define led_trigger_event(x, y) do {} while(0)
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#endif
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/* Trigger specific functions */
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#ifdef CONFIG_LEDS_TRIGGER_IDE_DISK
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extern void ledtrig_ide_activity(void);
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#else
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#define ledtrig_ide_activity() do {} while(0)
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#endif
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/*
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* Generic LED platform data for describing LED names and default triggers.
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*/
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struct led_info {
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const char *name;
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const char *default_trigger;
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int flags;
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};
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struct led_platform_data {
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int num_leds;
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struct led_info *leds;
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};
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/* For the leds-gpio driver */
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struct gpio_led {
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const char *name;
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const char *default_trigger;
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unsigned gpio;
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unsigned active_low : 1;
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unsigned retain_state_suspended : 1;
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unsigned default_state : 2;
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/* default_state should be one of LEDS_GPIO_DEFSTATE_(ON|OFF|KEEP) */
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};
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#define LEDS_GPIO_DEFSTATE_OFF 0
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#define LEDS_GPIO_DEFSTATE_ON 1
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#define LEDS_GPIO_DEFSTATE_KEEP 2
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struct gpio_led_platform_data {
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int num_leds;
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struct gpio_led *leds;
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int (*gpio_blink_set)(unsigned gpio,
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unsigned long *delay_on,
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unsigned long *delay_off);
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};
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#endif /* __LINUX_LEDS_H_INCLUDED */
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