1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * LTC2952 (PowerPath) driver
5 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
6 * Maintainer: René Moll <linux@r-moll.nl>
8 * ----------------------------------------
10 * ----------------------------------------
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 triggered
14 * and react by properly shutting down the system.
16 * This driver expects a device tree with a ltc2952 entry for pin mapping.
18 * ----------------------------------------
20 * ----------------------------------------
22 * The following GPIOs are used:
24 * A level change indicates the shut-down trigger. If it's state reverts
25 * within the time-out defined by trigger_delay, the shut down is not
26 * executed. If no pin is assigned to this input, the driver will start the
27 * watchdog toggle immediately. The chip will only power off the system if
28 * it is requested to do so through the kill line.
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.
35 * The last action during shut down is triggering this signalling, such
36 * that the PowerPath Control will power down the hardware.
38 * ----------------------------------------
40 * ----------------------------------------
42 * The driver requires a non-shared, edge-triggered interrupt on the trigger
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>
61 struct ltc2952_poweroff {
62 struct hrtimer timer_trigger;
63 struct hrtimer timer_wde;
65 ktime_t trigger_delay;
70 struct gpio_desc *gpio_trigger;
71 struct gpio_desc *gpio_watchdog;
72 struct gpio_desc *gpio_kill;
75 struct notifier_block panic_notifier;
78 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
81 * This global variable is only needed for pm_power_off. We should
82 * remove it entirely once we don't need the global state anymore.
84 static struct ltc2952_poweroff *ltc2952_data;
87 * ltc2952_poweroff_timer_wde - Timer callback
88 * Toggles the watchdog reset signal each wde_interval
90 * @timer: corresponding timer
92 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
93 * machine actually shuts down
95 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
99 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
101 if (data->kernel_panic)
102 return HRTIMER_NORESTART;
104 state = gpiod_get_value(data->gpio_watchdog);
105 gpiod_set_value(data->gpio_watchdog, !state);
107 now = hrtimer_cb_get_time(timer);
108 hrtimer_forward(timer, now, data->wde_interval);
110 return HRTIMER_RESTART;
113 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
115 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
118 static enum hrtimer_restart
119 ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
121 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
123 ltc2952_poweroff_start_wde(data);
124 dev_info(data->dev, "executing shutdown\n");
125 orderly_poweroff(true);
127 return HRTIMER_NORESTART;
131 * ltc2952_poweroff_handler - Interrupt handler
132 * Triggered each time the trigger signal changes state and (de)activates a
133 * time-out (timer_trigger). Once the time-out is actually reached the shut
137 * @dev_id: pointer to the main data structure
139 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
141 struct ltc2952_poweroff *data = dev_id;
143 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
144 /* shutdown is already triggered, nothing to do any more */
148 if (gpiod_get_value(data->gpio_trigger)) {
149 hrtimer_start(&data->timer_trigger, data->trigger_delay,
152 hrtimer_cancel(&data->timer_trigger);
157 static void ltc2952_poweroff_kill(void)
159 gpiod_set_value(ltc2952_data->gpio_kill, 1);
162 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
164 data->wde_interval = 300L * 1E6L;
165 data->trigger_delay = ktime_set(2, 500L*1E6L);
167 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
168 data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
170 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
171 data->timer_wde.function = ltc2952_poweroff_timer_wde;
174 static int ltc2952_poweroff_init(struct platform_device *pdev)
177 u32 trigger_delay_ms;
178 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
180 ltc2952_poweroff_default(data);
182 if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms",
183 &trigger_delay_ms)) {
184 data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC,
185 (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC);
188 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
190 if (IS_ERR(data->gpio_watchdog)) {
191 ret = PTR_ERR(data->gpio_watchdog);
192 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
196 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
197 if (IS_ERR(data->gpio_kill)) {
198 ret = PTR_ERR(data->gpio_kill);
199 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
203 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
205 if (IS_ERR(data->gpio_trigger)) {
207 * It's not a problem if the trigger gpio isn't available, but
208 * it is worth a warning if its use was defined in the device
211 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
212 data->gpio_trigger = NULL;
215 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
216 ltc2952_poweroff_handler,
217 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
221 * Some things may have happened:
222 * - No trigger input was defined
223 * - Claiming the GPIO failed
224 * - We could not map to an IRQ
225 * - We couldn't register an interrupt handler
227 * None of these really are problems, but all of them
228 * disqualify the push button from controlling the power.
230 * It is therefore important to note that if the ltc2952
231 * detects a button press for long enough, it will still start
232 * its own powerdown window and cut the power on us if we don't
233 * start the watchdog trigger.
235 if (data->gpio_trigger) {
237 "unable to configure the trigger interrupt\n");
238 devm_gpiod_put(&pdev->dev, data->gpio_trigger);
239 data->gpio_trigger = NULL;
242 "power down trigger input will not be used\n");
243 ltc2952_poweroff_start_wde(data);
249 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
250 unsigned long code, void *unused)
252 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
254 data->kernel_panic = true;
258 static int ltc2952_poweroff_probe(struct platform_device *pdev)
261 struct ltc2952_poweroff *data;
264 dev_err(&pdev->dev, "pm_power_off already registered");
268 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
272 data->dev = &pdev->dev;
273 platform_set_drvdata(pdev, data);
275 ret = ltc2952_poweroff_init(pdev);
279 /* TODO: remove ltc2952_data */
281 pm_power_off = ltc2952_poweroff_kill;
283 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
284 atomic_notifier_chain_register(&panic_notifier_list,
285 &data->panic_notifier);
286 dev_info(&pdev->dev, "probe successful\n");
291 static int ltc2952_poweroff_remove(struct platform_device *pdev)
293 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
296 hrtimer_cancel(&data->timer_trigger);
297 hrtimer_cancel(&data->timer_wde);
298 atomic_notifier_chain_unregister(&panic_notifier_list,
299 &data->panic_notifier);
303 static const struct of_device_id of_ltc2952_poweroff_match[] = {
304 { .compatible = "lltc,ltc2952"},
307 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
309 static struct platform_driver ltc2952_poweroff_driver = {
310 .probe = ltc2952_poweroff_probe,
311 .remove = ltc2952_poweroff_remove,
313 .name = "ltc2952-poweroff",
314 .of_match_table = of_ltc2952_poweroff_match,
318 module_platform_driver(ltc2952_poweroff_driver);
320 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
321 MODULE_DESCRIPTION("LTC PowerPath power-off driver");
322 MODULE_LICENSE("GPL v2");