diff options
Diffstat (limited to 'drivers/power/reset/ltc2952-poweroff.c')
| -rw-r--r-- | drivers/power/reset/ltc2952-poweroff.c | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/drivers/power/reset/ltc2952-poweroff.c b/drivers/power/reset/ltc2952-poweroff.c new file mode 100644 index 00000000000..116a1cef8f7 --- /dev/null +++ b/drivers/power/reset/ltc2952-poweroff.c @@ -0,0 +1,386 @@ +/* + * 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"); |