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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * LTC2952 (PowerPath) driver4 *5 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>6 * Maintainer: René Moll <linux@r-moll.nl>7 *8 * ----------------------------------------9 * - Description10 * ----------------------------------------11 *12 * This driver is to be used with an external PowerPath Controller (LTC2952).13 * Its function is to determine when a external shut down is triggered14 * and react by properly shutting down the system.15 *16 * This driver expects a device tree with a ltc2952 entry for pin mapping.17 *18 * ----------------------------------------19 * - GPIO20 * ----------------------------------------21 *22 * The following GPIOs are used:23 * - trigger (input)24 * A level change indicates the shut-down trigger. If it's state reverts25 * within the time-out defined by trigger_delay, the shut down is not26 * executed. If no pin is assigned to this input, the driver will start the27 * watchdog toggle immediately. The chip will only power off the system if28 * it is requested to do so through the kill line.29 *30 * - watchdog (output)31 * Once a shut down is triggered, the driver will toggle this signal,32 * with an internal (wde_interval) to stall the hardware shut down.33 *34 * - kill (output)35 * The last action during shut down is triggering this signalling, such36 * that the PowerPath Control will power down the hardware.37 *38 * ----------------------------------------39 * - Interrupts40 * ----------------------------------------41 *42 * The driver requires a non-shared, edge-triggered interrupt on the trigger43 * GPIO.44 */45 46#include <linux/kernel.h>47#include <linux/init.h>48#include <linux/interrupt.h>49#include <linux/device.h>50#include <linux/platform_device.h>51#include <linux/ktime.h>52#include <linux/slab.h>53#include <linux/kmod.h>54#include <linux/module.h>55#include <linux/panic_notifier.h>56#include <linux/mod_devicetable.h>57#include <linux/gpio/consumer.h>58#include <linux/reboot.h>59#include <linux/property.h>60 61struct ltc2952_poweroff {62 struct hrtimer timer_trigger;63 struct hrtimer timer_wde;64 65 ktime_t trigger_delay;66 ktime_t wde_interval;67 68 struct device *dev;69 70 struct gpio_desc *gpio_trigger;71 struct gpio_desc *gpio_watchdog;72 struct gpio_desc *gpio_kill;73 74 bool kernel_panic;75 struct notifier_block panic_notifier;76};77 78#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)79 80/*81 * This global variable is only needed for pm_power_off. We should82 * remove it entirely once we don't need the global state anymore.83 */84static struct ltc2952_poweroff *ltc2952_data;85 86/**87 * ltc2952_poweroff_timer_wde - Timer callback88 * Toggles the watchdog reset signal each wde_interval89 *90 * @timer: corresponding timer91 *92 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the93 * machine actually shuts down94 */95static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)96{97 int state;98 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);99 100 if (data->kernel_panic)101 return HRTIMER_NORESTART;102 103 state = gpiod_get_value(data->gpio_watchdog);104 gpiod_set_value(data->gpio_watchdog, !state);105 106 hrtimer_forward_now(timer, data->wde_interval);107 108 return HRTIMER_RESTART;109}110 111static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)112{113 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);114}115 116static enum hrtimer_restart117ltc2952_poweroff_timer_trigger(struct hrtimer *timer)118{119 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);120 121 ltc2952_poweroff_start_wde(data);122 dev_info(data->dev, "executing shutdown\n");123 orderly_poweroff(true);124 125 return HRTIMER_NORESTART;126}127 128/**129 * ltc2952_poweroff_handler - Interrupt handler130 * Triggered each time the trigger signal changes state and (de)activates a131 * time-out (timer_trigger). Once the time-out is actually reached the shut132 * down is executed.133 *134 * @irq: IRQ number135 * @dev_id: pointer to the main data structure136 */137static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)138{139 struct ltc2952_poweroff *data = dev_id;140 141 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {142 /* shutdown is already triggered, nothing to do any more */143 return IRQ_HANDLED;144 }145 146 if (gpiod_get_value(data->gpio_trigger)) {147 hrtimer_start(&data->timer_trigger, data->trigger_delay,148 HRTIMER_MODE_REL);149 } else {150 hrtimer_cancel(&data->timer_trigger);151 }152 return IRQ_HANDLED;153}154 155static void ltc2952_poweroff_kill(void)156{157 gpiod_set_value(ltc2952_data->gpio_kill, 1);158}159 160static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)161{162 data->wde_interval = 300L * NSEC_PER_MSEC;163 data->trigger_delay = ktime_set(2, 500L * NSEC_PER_MSEC);164 165 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);166 data->timer_trigger.function = ltc2952_poweroff_timer_trigger;167 168 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);169 data->timer_wde.function = ltc2952_poweroff_timer_wde;170}171 172static int ltc2952_poweroff_init(struct platform_device *pdev)173{174 int ret;175 u32 trigger_delay_ms;176 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);177 178 ltc2952_poweroff_default(data);179 180 if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms",181 &trigger_delay_ms)) {182 data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC,183 (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC);184 }185 186 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",187 GPIOD_OUT_LOW);188 if (IS_ERR(data->gpio_watchdog)) {189 ret = PTR_ERR(data->gpio_watchdog);190 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");191 return ret;192 }193 194 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);195 if (IS_ERR(data->gpio_kill)) {196 ret = PTR_ERR(data->gpio_kill);197 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");198 return ret;199 }200 201 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",202 GPIOD_IN);203 if (IS_ERR(data->gpio_trigger)) {204 /*205 * It's not a problem if the trigger gpio isn't available, but206 * it is worth a warning if its use was defined in the device207 * tree.208 */209 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");210 data->gpio_trigger = NULL;211 }212 213 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),214 ltc2952_poweroff_handler,215 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),216 "ltc2952-poweroff",217 data)) {218 /*219 * Some things may have happened:220 * - No trigger input was defined221 * - Claiming the GPIO failed222 * - We could not map to an IRQ223 * - We couldn't register an interrupt handler224 *225 * None of these really are problems, but all of them226 * disqualify the push button from controlling the power.227 *228 * It is therefore important to note that if the ltc2952229 * detects a button press for long enough, it will still start230 * its own powerdown window and cut the power on us if we don't231 * start the watchdog trigger.232 */233 if (data->gpio_trigger) {234 dev_warn(&pdev->dev,235 "unable to configure the trigger interrupt\n");236 devm_gpiod_put(&pdev->dev, data->gpio_trigger);237 data->gpio_trigger = NULL;238 }239 dev_info(&pdev->dev,240 "power down trigger input will not be used\n");241 ltc2952_poweroff_start_wde(data);242 }243 244 return 0;245}246 247static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,248 unsigned long code, void *unused)249{250 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);251 252 data->kernel_panic = true;253 return NOTIFY_DONE;254}255 256static int ltc2952_poweroff_probe(struct platform_device *pdev)257{258 int ret;259 struct ltc2952_poweroff *data;260 261 if (pm_power_off) {262 dev_err(&pdev->dev, "pm_power_off already registered");263 return -EBUSY;264 }265 266 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);267 if (!data)268 return -ENOMEM;269 270 data->dev = &pdev->dev;271 platform_set_drvdata(pdev, data);272 273 ret = ltc2952_poweroff_init(pdev);274 if (ret)275 return ret;276 277 /* TODO: remove ltc2952_data */278 ltc2952_data = data;279 pm_power_off = ltc2952_poweroff_kill;280 281 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;282 atomic_notifier_chain_register(&panic_notifier_list,283 &data->panic_notifier);284 dev_info(&pdev->dev, "probe successful\n");285 286 return 0;287}288 289static void ltc2952_poweroff_remove(struct platform_device *pdev)290{291 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);292 293 pm_power_off = NULL;294 hrtimer_cancel(&data->timer_trigger);295 hrtimer_cancel(&data->timer_wde);296 atomic_notifier_chain_unregister(&panic_notifier_list,297 &data->panic_notifier);298}299 300static const struct of_device_id of_ltc2952_poweroff_match[] = {301 { .compatible = "lltc,ltc2952"},302 {},303};304MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);305 306static struct platform_driver ltc2952_poweroff_driver = {307 .probe = ltc2952_poweroff_probe,308 .remove_new = ltc2952_poweroff_remove,309 .driver = {310 .name = "ltc2952-poweroff",311 .of_match_table = of_ltc2952_poweroff_match,312 },313};314 315module_platform_driver(ltc2952_poweroff_driver);316 317MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");318MODULE_DESCRIPTION("LTC PowerPath power-off driver");319