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/mod_devicetable.h>
56 #include <linux/gpio/consumer.h>
57 #include <linux/reboot.h>
58 #include <linux/property.h>
60 struct ltc2952_poweroff {
61 struct hrtimer timer_trigger;
62 struct hrtimer timer_wde;
64 ktime_t trigger_delay;
69 struct gpio_desc *gpio_trigger;
70 struct gpio_desc *gpio_watchdog;
71 struct gpio_desc *gpio_kill;
74 struct notifier_block panic_notifier;
77 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
80 * This global variable is only needed for pm_power_off. We should
81 * remove it entirely once we don't need the global state anymore.
83 static struct ltc2952_poweroff *ltc2952_data;
86 * ltc2952_poweroff_timer_wde - Timer callback
87 * Toggles the watchdog reset signal each wde_interval
89 * @timer: corresponding timer
91 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
92 * machine actually shuts down
94 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
98 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
100 if (data->kernel_panic)
101 return HRTIMER_NORESTART;
103 state = gpiod_get_value(data->gpio_watchdog);
104 gpiod_set_value(data->gpio_watchdog, !state);
106 now = hrtimer_cb_get_time(timer);
107 hrtimer_forward(timer, now, data->wde_interval);
109 return HRTIMER_RESTART;
112 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
114 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
117 static enum hrtimer_restart
118 ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
120 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
122 ltc2952_poweroff_start_wde(data);
123 dev_info(data->dev, "executing shutdown\n");
124 orderly_poweroff(true);
126 return HRTIMER_NORESTART;
130 * ltc2952_poweroff_handler - Interrupt handler
131 * Triggered each time the trigger signal changes state and (de)activates a
132 * time-out (timer_trigger). Once the time-out is actually reached the shut
136 * @dev_id: pointer to the main data structure
138 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
140 struct ltc2952_poweroff *data = dev_id;
142 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
143 /* shutdown is already triggered, nothing to do any more */
147 if (gpiod_get_value(data->gpio_trigger)) {
148 hrtimer_start(&data->timer_trigger, data->trigger_delay,
151 hrtimer_cancel(&data->timer_trigger);
156 static void ltc2952_poweroff_kill(void)
158 gpiod_set_value(ltc2952_data->gpio_kill, 1);
161 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
163 data->wde_interval = 300L * 1E6L;
164 data->trigger_delay = ktime_set(2, 500L*1E6L);
166 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
167 data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
169 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
170 data->timer_wde.function = ltc2952_poweroff_timer_wde;
173 static int ltc2952_poweroff_init(struct platform_device *pdev)
176 u32 trigger_delay_ms;
177 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
179 ltc2952_poweroff_default(data);
181 if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms",
182 &trigger_delay_ms)) {
183 data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC,
184 (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC);
187 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
189 if (IS_ERR(data->gpio_watchdog)) {
190 ret = PTR_ERR(data->gpio_watchdog);
191 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
195 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
196 if (IS_ERR(data->gpio_kill)) {
197 ret = PTR_ERR(data->gpio_kill);
198 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
202 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
204 if (IS_ERR(data->gpio_trigger)) {
206 * It's not a problem if the trigger gpio isn't available, but
207 * it is worth a warning if its use was defined in the device
210 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
211 data->gpio_trigger = NULL;
214 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
215 ltc2952_poweroff_handler,
216 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
220 * Some things may have happened:
221 * - No trigger input was defined
222 * - Claiming the GPIO failed
223 * - We could not map to an IRQ
224 * - We couldn't register an interrupt handler
226 * None of these really are problems, but all of them
227 * disqualify the push button from controlling the power.
229 * It is therefore important to note that if the ltc2952
230 * detects a button press for long enough, it will still start
231 * its own powerdown window and cut the power on us if we don't
232 * start the watchdog trigger.
234 if (data->gpio_trigger) {
236 "unable to configure the trigger interrupt\n");
237 devm_gpiod_put(&pdev->dev, data->gpio_trigger);
238 data->gpio_trigger = NULL;
241 "power down trigger input will not be used\n");
242 ltc2952_poweroff_start_wde(data);
248 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
249 unsigned long code, void *unused)
251 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
253 data->kernel_panic = true;
257 static int ltc2952_poweroff_probe(struct platform_device *pdev)
260 struct ltc2952_poweroff *data;
263 dev_err(&pdev->dev, "pm_power_off already registered");
267 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
271 data->dev = &pdev->dev;
272 platform_set_drvdata(pdev, data);
274 ret = ltc2952_poweroff_init(pdev);
278 /* TODO: remove ltc2952_data */
280 pm_power_off = ltc2952_poweroff_kill;
282 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
283 atomic_notifier_chain_register(&panic_notifier_list,
284 &data->panic_notifier);
285 dev_info(&pdev->dev, "probe successful\n");
290 static int ltc2952_poweroff_remove(struct platform_device *pdev)
292 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
295 hrtimer_cancel(&data->timer_trigger);
296 hrtimer_cancel(&data->timer_wde);
297 atomic_notifier_chain_unregister(&panic_notifier_list,
298 &data->panic_notifier);
302 static const struct of_device_id of_ltc2952_poweroff_match[] = {
303 { .compatible = "lltc,ltc2952"},
306 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
308 static struct platform_driver ltc2952_poweroff_driver = {
309 .probe = ltc2952_poweroff_probe,
310 .remove = ltc2952_poweroff_remove,
312 .name = "ltc2952-poweroff",
313 .of_match_table = of_ltc2952_poweroff_match,
317 module_platform_driver(ltc2952_poweroff_driver);
319 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
320 MODULE_DESCRIPTION("LTC PowerPath power-off driver");
321 MODULE_LICENSE("GPL v2");