diff options
Diffstat (limited to 'drivers/power/reset/ltc2952-poweroff.c')
| -rw-r--r-- | drivers/power/reset/ltc2952-poweroff.c | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/drivers/power/reset/ltc2952-poweroff.c b/drivers/power/reset/ltc2952-poweroff.c new file mode 100644 index 000000000..8a76ef841 --- /dev/null +++ b/drivers/power/reset/ltc2952-poweroff.c @@ -0,0 +1,324 @@ +/* + * 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/mod_devicetable.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); + } + 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 = 300L * NSEC_PER_MSEC; + data->trigger_delay = ktime_set(2, 500L * NSEC_PER_MSEC); + + 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_optional(&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. + */ + 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"); |