/*
* LTC2952 (PowerPath) driver
*
* Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
* Maintainer: René Moll <linux@r-moll.nl>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* ----------------------------------------
* - Description
* ----------------------------------------
*
* This driver is to be used with an external PowerPath Controller (LTC2952).
* Its function is to determine when a external shut down is triggered
* and react by properly shutting down the system.
*
* This driver expects a device tree with a ltc2952 entry for pin mapping.
*
* ----------------------------------------
* - GPIO
* ----------------------------------------
*
* The following GPIOs are used:
* - trigger (input)
* A level change indicates the shut-down trigger. If it's state reverts
* within the time-out defined by trigger_delay, the shut down is not
* executed. If no pin is assigned to this input, the driver will start the
* watchdog toggle immediately. The chip will only power off the system if
* it is requested to do so through the kill line.
*
* - watchdog (output)
* Once a shut down is triggered, the driver will toggle this signal,
* with an internal (wde_interval) to stall the hardware shut down.
*
* - kill (output)
* The last action during shut down is triggering this signalling, such
* that the PowerPath Control will power down the hardware.
*
* ----------------------------------------
* - Interrupts
* ----------------------------------------
*
* The driver requires a non-shared, edge-triggered interrupt on the trigger
* GPIO.
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/gpio/consumer.h>
#include <linux/reboot.h>
struct ltc2952_poweroff {
struct hrtimer timer_trigger;
struct hrtimer timer_wde;
ktime_t trigger_delay;
ktime_t wde_interval;
struct device *dev;
struct gpio_desc *gpio_trigger;
struct gpio_desc *gpio_watchdog;
struct gpio_desc *gpio_kill;
bool kernel_panic;
struct notifier_block panic_notifier;
};
#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
/*
* This global variable is only needed for pm_power_off. We should
* remove it entirely once we don't need the global state anymore.
*/
static struct ltc2952_poweroff *ltc2952_data;
/**
* ltc2952_poweroff_timer_wde - Timer callback
* Toggles the watchdog reset signal each wde_interval
*
* @timer: corresponding timer
*
* Returns HRTIMER_RESTART for an infinite loop which will only stop when the
* machine actually shuts down
*/
static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
{
ktime_t now;
int state;
unsigned long overruns;
struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
if (data->kernel_panic)
return HRTIMER_NORESTART;
state = gpiod_get_value(data->gpio_watchdog);
gpiod_set_value(data->gpio_watchdog, !state);
now = hrtimer_cb_get_time(timer);
overruns = hrtimer_forward(timer, now, data->wde_interval);
return HRTIMER_RESTART;
}
static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
{
hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
}
static enum hrtimer_restart
ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
{
struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
ltc2952_poweroff_start_wde(data);
dev_info(data->dev, "executing shutdown\n");
orderly_poweroff(true);
return HRTIMER_NORESTART;
}
/**
* ltc2952_poweroff_handler - Interrupt handler
* Triggered each time the trigger signal changes state and (de)activates a
* time-out (timer_trigger). Once the time-out is actually reached the shut
* down is executed.
*
* @irq: IRQ number
* @dev_id: pointer to the main data structure
*/
static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
{
struct ltc2952_poweroff *data = dev_id;
if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
/* shutdown is already triggered, nothing to do any more */
return IRQ_HANDLED;
}
if (gpiod_get_value(data->gpio_trigger)) {
hrtimer_start(&data->timer_trigger, data->trigger_delay,
HRTIMER_MODE_REL);
} else {
hrtimer_cancel(&data->timer_trigger);
/* omitting return value check, timer should have been valid */
}
return IRQ_HANDLED;
}
static void ltc2952_poweroff_kill(void)
{
gpiod_set_value(ltc2952_data->gpio_kill, 1);
}
static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
{
data->wde_interval = ktime_set(0, 300L*1E6L);
data->trigger_delay = ktime_set(2, 500L*1E6L);
hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
data->timer_wde.function = ltc2952_poweroff_timer_wde;
}
static int ltc2952_poweroff_init(struct platform_device *pdev)
{
int ret;
struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
ltc2952_poweroff_default(data);
data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
GPIOD_OUT_LOW);
if (IS_ERR(data->gpio_watchdog)) {
ret = PTR_ERR(data->gpio_watchdog);
dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
return ret;
}
data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
if (IS_ERR(data->gpio_kill)) {
ret = PTR_ERR(data->gpio_kill);
dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
return ret;
}
data->gpio_trigger = devm_gpiod_get(&pdev->dev, "trigger", GPIOD_IN);
if (IS_ERR(data->gpio_trigger)) {
/*
* It's not a problem if the trigger gpio isn't available, but
* it is worth a warning if its use was defined in the device
* tree.
*/
if (PTR_ERR(data->gpio_trigger) != -ENOENT)
dev_err(&pdev->dev,
"unable to claim gpio \"trigger\"\n");
data->gpio_trigger = NULL;
}
if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
ltc2952_poweroff_handler,
(IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
"ltc2952-poweroff",
data)) {
/*
* Some things may have happened:
* - No trigger input was defined
* - Claiming the GPIO failed
* - We could not map to an IRQ
* - We couldn't register an interrupt handler
*
* None of these really are problems, but all of them
* disqualify the push button from controlling the power.
*
* It is therefore important to note that if the ltc2952
* detects a button press for long enough, it will still start
* its own powerdown window and cut the power on us if we don't
* start the watchdog trigger.
*/
if (data->gpio_trigger) {
dev_warn(&pdev->dev,
"unable to configure the trigger interrupt\n");
devm_gpiod_put(&pdev->dev, data->gpio_trigger);
data->gpio_trigger = NULL;
}
dev_info(&pdev->dev,
"power down trigger input will not be used\n");
ltc2952_poweroff_start_wde(data);
}
return 0;
}
static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
unsigned long code, void *unused)
{
struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
data->kernel_panic = true;
return NOTIFY_DONE;
}
static int ltc2952_poweroff_probe(struct platform_device *pdev)
{
int ret;
struct ltc2952_poweroff *data;
if (pm_power_off) {
dev_err(&pdev->dev, "pm_power_off already registered");
return -EBUSY;
}
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->dev = &pdev->dev;
platform_set_drvdata(pdev, data);
ret = ltc2952_poweroff_init(pdev);
if (ret)
return ret;
/* TODO: remove ltc2952_data */
ltc2952_data = data;
pm_power_off = ltc2952_poweroff_kill;
data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
atomic_notifier_chain_register(&panic_notifier_list,
&data->panic_notifier);
dev_info(&pdev->dev, "probe successful\n");
return 0;
}
static int ltc2952_poweroff_remove(struct platform_device *pdev)
{
struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
pm_power_off = NULL;
hrtimer_cancel(&data->timer_trigger);
hrtimer_cancel(&data->timer_wde);
atomic_notifier_chain_unregister(&panic_notifier_list,
&data->panic_notifier);
return 0;
}
static const struct of_device_id of_ltc2952_poweroff_match[] = {
{ .compatible = "lltc,ltc2952"},
{},
};
MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
static struct platform_driver ltc2952_poweroff_driver = {
.probe = ltc2952_poweroff_probe,
.remove = ltc2952_poweroff_remove,
.driver = {
.name = "ltc2952-poweroff",
.of_match_table = of_ltc2952_poweroff_match,
},
};
module_platform_driver(ltc2952_poweroff_driver);
MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
MODULE_DESCRIPTION("LTC PowerPath power-off driver");
MODULE_LICENSE("GPL v2");
