/* * LTC2952 (PowerPath) driver * * Copyright (C) 2014, Xsens Technologies BV * Maintainer: René Moll * * 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 #include #include #include #include #include #include #include #include #include #include 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); /* omitting return value check, timer should have been valid */ } 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 = 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 = 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 "); MODULE_DESCRIPTION("LTC PowerPath power-off driver"); MODULE_LICENSE("GPL v2");