/*
* 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.
*
* - 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_data {
struct hrtimer timer_trigger;
struct hrtimer timer_wde;
ktime_t trigger_delay;
ktime_t wde_interval;
struct device *dev;
unsigned int virq;
/**
* 0: trigger
* 1: watchdog
* 2: kill
*/
struct gpio_desc *gpio[3];
};
static int ltc2952_poweroff_panic;
static struct ltc2952_poweroff_data *ltc2952_data;
#define POWERPATH_IO_TRIGGER 0
#define POWERPATH_IO_WATCHDOG 1
#define POWERPATH_IO_KILL 2
/**
* 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;
if (ltc2952_poweroff_panic)
return HRTIMER_NORESTART;
state = gpiod_get_value(ltc2952_data->gpio[POWERPATH_IO_WATCHDOG]);
gpiod_set_value(ltc2952_data->gpio[POWERPATH_IO_WATCHDOG], !state);
now = hrtimer_cb_get_time(timer);
overruns = hrtimer_forward(timer, now, ltc2952_data->wde_interval);
return HRTIMER_RESTART;
}
static enum hrtimer_restart ltc2952_poweroff_timer_trigger(
struct hrtimer *timer)
{
int ret;
ret = hrtimer_start(<c2952_data->timer_wde,
ltc2952_data->wde_interval, HRTIMER_MODE_REL);
if (ret) {
dev_err(ltc2952_data->dev, "unable to start the timer\n");
/*
* The device will not toggle the watchdog reset,
* thus shut down is only safe if the PowerPath controller
* has a long enough time-off before triggering a hardware
* power-off.
*
* Only sending a warning as the system will power-off anyway
*/
}
dev_info(ltc2952_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)
{
int ret;
struct ltc2952_poweroff_data *data = dev_id;
if (ltc2952_poweroff_panic)
goto irq_ok;
if (hrtimer_active(&data->timer_wde)) {
/* shutdown is already triggered, nothing to do any more */
goto irq_ok;
}
if (!hrtimer_active(&data->timer_trigger)) {
ret = hrtimer_start(&data->timer_trigger, data->trigger_delay,
HRTIMER_MODE_REL);
if (ret)
dev_err(data->dev, "unable to start the wait timer\n");
} else {
ret = hrtimer_cancel(&data->timer_trigger);
/* omitting return value check, timer should have been valid */
}
irq_ok:
return IRQ_HANDLED;
}
static void ltc2952_poweroff_kill(void)
{
gpiod_set_value(ltc2952_data->gpio[POWERPATH_IO_KILL], 1);
}
static int ltc2952_poweroff_suspend(struct platform_device *pdev,
pm_message_t state)
{
return -ENOSYS;
}
static int ltc2952_poweroff_resume(struct platform_device *pdev)
{
return -ENOSYS;
}
static void ltc2952_poweroff_default(struct ltc2952_poweroff_data *data)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(data->gpio); i++)
data->gpio[i] = NULL;
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 = <c2952_poweroff_timer_trigger;
hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
data->timer_wde.function = <c2952_poweroff_timer_wde;
}
static int ltc2952_poweroff_init(struct platform_device *pdev)
{
int ret, virq;
unsigned int i;
struct ltc2952_poweroff_data *data;
static char *name[] = {
"trigger",
"watchdog",
"kill",
NULL
};
data = ltc2952_data;
ltc2952_poweroff_default(ltc2952_data);
for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++) {
ltc2952_data->gpio[i] = gpiod_get(&pdev->dev, name[i]);
if (IS_ERR(ltc2952_data->gpio[i])) {
ret = PTR_ERR(ltc2952_data->gpio[i]);
dev_err(&pdev->dev,
"unable to claim the following gpio: %s\n",
name[i]);
goto err_io;
}
}
ret = gpiod_direction_output(
ltc2952_data->gpio[POWERPATH_IO_WATCHDOG], 0);
if (ret) {
dev_err(&pdev->dev, "unable to use watchdog-gpio as output\n");
goto err_io;
}
ret = gpiod_direction_output(ltc2952_data->gpio[POWERPATH_IO_KILL], 0);
if (ret) {
dev_err(&pdev->dev, "unable to use kill-gpio as output\n");
goto err_io;
}
virq = gpiod_to_irq(ltc2952_data->gpio[POWERPATH_IO_TRIGGER]);
if (virq < 0) {
dev_err(&pdev->dev, "cannot map GPIO as interrupt");
goto err_io;
}
ltc2952_data->virq = virq;
ret = request_irq(virq,
ltc2952_poweroff_handler,
(IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
"ltc2952-poweroff",
ltc2952_data
);
if (ret) {
dev_err(&pdev->dev, "cannot configure an interrupt handler\n");
goto err_io;
}
return 0;
err_io:
for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++)
if (ltc2952_data->gpio[i])
gpiod_put(ltc2952_data->gpio[i]);
return ret;
}
static int ltc2952_poweroff_probe(struct platform_device *pdev)
{
int ret;
if (pm_power_off) {
dev_err(&pdev->dev, "pm_power_off already registered");
return -EBUSY;
}
ltc2952_data = kzalloc(sizeof(*ltc2952_data), GFP_KERNEL);
if (!ltc2952_data)
return -ENOMEM;
ltc2952_data->dev = &pdev->dev;
ret = ltc2952_poweroff_init(pdev);
if (ret)
goto err;
pm_power_off = <c2952_poweroff_kill;
dev_info(&pdev->dev, "probe successful\n");
return 0;
err:
kfree(ltc2952_data);
return ret;
}
static int ltc2952_poweroff_remove(struct platform_device *pdev)
{
unsigned int i;
pm_power_off = NULL;
if (ltc2952_data) {
free_irq(ltc2952_data->virq, ltc2952_data);
for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++)
gpiod_put(ltc2952_data->gpio[i]);
kfree(ltc2952_data);
}
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",
.owner = THIS_MODULE,
.of_match_table = of_ltc2952_poweroff_match,
},
.suspend = ltc2952_poweroff_suspend,
.resume = ltc2952_poweroff_resume,
};
static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
unsigned long code, void *unused)
{
ltc2952_poweroff_panic = 1;
return NOTIFY_DONE;
}
static struct notifier_block ltc2952_poweroff_panic_nb = {
.notifier_call = ltc2952_poweroff_notify_panic,
};
static int __init ltc2952_poweroff_platform_init(void)
{
ltc2952_poweroff_panic = 0;
atomic_notifier_chain_register(&panic_notifier_list,
<c2952_poweroff_panic_nb);
return platform_driver_register(<c2952_poweroff_driver);
}
static void __exit ltc2952_poweroff_platform_exit(void)
{
atomic_notifier_chain_unregister(&panic_notifier_list,
<c2952_poweroff_panic_nb);
platform_driver_unregister(<c2952_poweroff_driver);
}
module_init(ltc2952_poweroff_platform_init);
module_exit(ltc2952_poweroff_platform_exit);
MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
MODULE_DESCRIPTION("LTC PowerPath power-off driver");
MODULE_LICENSE("GPL v2");
