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322 lines
9.0 KiB
322 lines
9.0 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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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 <[email protected]> |
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* Maintainer: René Moll <[email protected]> |
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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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#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/panic_notifier.h> |
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#include <linux/mod_devicetable.h> |
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#include <linux/gpio/consumer.h> |
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#include <linux/reboot.h> |
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#include <linux/property.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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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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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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u32 trigger_delay_ms; |
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struct ltc2952_poweroff *data = platform_get_drvdata(pdev); |
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ltc2952_poweroff_default(data); |
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if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms", |
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&trigger_delay_ms)) { |
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data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC, |
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(trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC); |
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} |
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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("René Moll <[email protected]>"); |
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MODULE_DESCRIPTION("LTC PowerPath power-off driver"); |
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MODULE_LICENSE("GPL v2");
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