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