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René Moll66471562014-08-08 13:12:17 +00001/*
2 * LTC2952 (PowerPath) driver
3 *
4 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
5 * Maintainer: René Moll <linux@r-moll.nl>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * ----------------------------------------
18 * - Description
19 * ----------------------------------------
20 *
21 * This driver is to be used with an external PowerPath Controller (LTC2952).
22 * Its function is to determine when a external shut down is triggered
23 * and react by properly shutting down the system.
24 *
25 * This driver expects a device tree with a ltc2952 entry for pin mapping.
26 *
27 * ----------------------------------------
28 * - GPIO
29 * ----------------------------------------
30 *
31 * The following GPIOs are used:
32 * - trigger (input)
33 * A level change indicates the shut-down trigger. If it's state reverts
34 * within the time-out defined by trigger_delay, the shut down is not
Frans Klaveree181852015-01-14 09:15:45 +010035 * executed. If no pin is assigned to this input, the driver will start the
36 * watchdog toggle immediately. The chip will only power off the system if
37 * it is requested to do so through the kill line.
René Moll66471562014-08-08 13:12:17 +000038 *
39 * - watchdog (output)
40 * Once a shut down is triggered, the driver will toggle this signal,
41 * with an internal (wde_interval) to stall the hardware shut down.
42 *
43 * - kill (output)
44 * The last action during shut down is triggering this signalling, such
45 * that the PowerPath Control will power down the hardware.
46 *
47 * ----------------------------------------
48 * - Interrupts
49 * ----------------------------------------
50 *
51 * The driver requires a non-shared, edge-triggered interrupt on the trigger
52 * GPIO.
53 *
54 */
55
56#include <linux/kernel.h>
57#include <linux/init.h>
58#include <linux/interrupt.h>
59#include <linux/device.h>
60#include <linux/platform_device.h>
61#include <linux/ktime.h>
62#include <linux/slab.h>
63#include <linux/kmod.h>
64#include <linux/module.h>
65#include <linux/gpio/consumer.h>
66#include <linux/reboot.h>
67
Frans Klavera5f67be2015-01-14 09:15:38 +010068struct ltc2952_poweroff {
René Moll66471562014-08-08 13:12:17 +000069 struct hrtimer timer_trigger;
70 struct hrtimer timer_wde;
71
72 ktime_t trigger_delay;
73 ktime_t wde_interval;
74
75 struct device *dev;
76
Frans Klaverf66472d2015-01-14 09:15:36 +010077 struct gpio_desc *gpio_trigger;
78 struct gpio_desc *gpio_watchdog;
79 struct gpio_desc *gpio_kill;
Frans Klaver818ca4c2015-01-14 09:15:39 +010080
81 bool kernel_panic;
82 struct notifier_block panic_notifier;
René Moll66471562014-08-08 13:12:17 +000083};
84
Frans Klavera5f67be2015-01-14 09:15:38 +010085#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
86
87/*
88 * This global variable is only needed for pm_power_off. We should
89 * remove it entirely once we don't need the global state anymore.
90 */
91static struct ltc2952_poweroff *ltc2952_data;
René Moll66471562014-08-08 13:12:17 +000092
René Moll66471562014-08-08 13:12:17 +000093/**
94 * ltc2952_poweroff_timer_wde - Timer callback
95 * Toggles the watchdog reset signal each wde_interval
96 *
97 * @timer: corresponding timer
98 *
99 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
100 * machine actually shuts down
101 */
102static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
103{
104 ktime_t now;
105 int state;
106 unsigned long overruns;
Frans Klavera5f67be2015-01-14 09:15:38 +0100107 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
René Moll66471562014-08-08 13:12:17 +0000108
Frans Klaver818ca4c2015-01-14 09:15:39 +0100109 if (data->kernel_panic)
René Moll66471562014-08-08 13:12:17 +0000110 return HRTIMER_NORESTART;
111
Frans Klavera5f67be2015-01-14 09:15:38 +0100112 state = gpiod_get_value(data->gpio_watchdog);
113 gpiod_set_value(data->gpio_watchdog, !state);
René Moll66471562014-08-08 13:12:17 +0000114
115 now = hrtimer_cb_get_time(timer);
Frans Klavera5f67be2015-01-14 09:15:38 +0100116 overruns = hrtimer_forward(timer, now, data->wde_interval);
René Moll66471562014-08-08 13:12:17 +0000117
118 return HRTIMER_RESTART;
119}
120
Frans Klaveree181852015-01-14 09:15:45 +0100121static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
René Moll66471562014-08-08 13:12:17 +0000122{
Thomas Gleixner4101ecc2015-04-13 16:43:35 +0200123 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
Frans Klaveree181852015-01-14 09:15:45 +0100124}
René Moll66471562014-08-08 13:12:17 +0000125
Frans Klaveree181852015-01-14 09:15:45 +0100126static enum hrtimer_restart
127ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
128{
129 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
130
131 ltc2952_poweroff_start_wde(data);
Frans Klavera5f67be2015-01-14 09:15:38 +0100132 dev_info(data->dev, "executing shutdown\n");
René Moll66471562014-08-08 13:12:17 +0000133 orderly_poweroff(true);
134
135 return HRTIMER_NORESTART;
136}
137
138/**
139 * ltc2952_poweroff_handler - Interrupt handler
140 * Triggered each time the trigger signal changes state and (de)activates a
141 * time-out (timer_trigger). Once the time-out is actually reached the shut
142 * down is executed.
143 *
144 * @irq: IRQ number
145 * @dev_id: pointer to the main data structure
146 */
147static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
148{
Frans Klavera5f67be2015-01-14 09:15:38 +0100149 struct ltc2952_poweroff *data = dev_id;
René Moll66471562014-08-08 13:12:17 +0000150
Frans Klaver5c3faad2015-01-14 09:15:41 +0100151 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
René Moll66471562014-08-08 13:12:17 +0000152 /* shutdown is already triggered, nothing to do any more */
Frans Klaver5c3faad2015-01-14 09:15:41 +0100153 return IRQ_HANDLED;
René Moll66471562014-08-08 13:12:17 +0000154 }
155
Frans Klaverc1ada2f2015-01-14 09:15:44 +0100156 if (gpiod_get_value(data->gpio_trigger)) {
Thomas Gleixner4101ecc2015-04-13 16:43:35 +0200157 hrtimer_start(&data->timer_trigger, data->trigger_delay,
158 HRTIMER_MODE_REL);
René Moll66471562014-08-08 13:12:17 +0000159 } else {
Frans Klaver5c3faad2015-01-14 09:15:41 +0100160 hrtimer_cancel(&data->timer_trigger);
René Moll66471562014-08-08 13:12:17 +0000161 }
René Moll66471562014-08-08 13:12:17 +0000162 return IRQ_HANDLED;
163}
164
165static void ltc2952_poweroff_kill(void)
166{
Frans Klaverf66472d2015-01-14 09:15:36 +0100167 gpiod_set_value(ltc2952_data->gpio_kill, 1);
René Moll66471562014-08-08 13:12:17 +0000168}
169
Frans Klavera5f67be2015-01-14 09:15:38 +0100170static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
René Moll66471562014-08-08 13:12:17 +0000171{
Nathan Chancellor23f4bbf2021-11-05 08:20:50 -0700172 data->wde_interval = 300L * NSEC_PER_MSEC;
173 data->trigger_delay = ktime_set(2, 500L * NSEC_PER_MSEC);
René Moll66471562014-08-08 13:12:17 +0000174
175 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
Frans Klaver5689b782015-01-14 09:15:42 +0100176 data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
René Moll66471562014-08-08 13:12:17 +0000177
178 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
Frans Klaver5689b782015-01-14 09:15:42 +0100179 data->timer_wde.function = ltc2952_poweroff_timer_wde;
René Moll66471562014-08-08 13:12:17 +0000180}
181
182static int ltc2952_poweroff_init(struct platform_device *pdev)
183{
Frans Klaveree181852015-01-14 09:15:45 +0100184 int ret;
Frans Klavera5f67be2015-01-14 09:15:38 +0100185 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
René Moll66471562014-08-08 13:12:17 +0000186
Frans Klavera5f67be2015-01-14 09:15:38 +0100187 ltc2952_poweroff_default(data);
René Moll66471562014-08-08 13:12:17 +0000188
Frans Klavera5f67be2015-01-14 09:15:38 +0100189 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
190 GPIOD_OUT_LOW);
191 if (IS_ERR(data->gpio_watchdog)) {
192 ret = PTR_ERR(data->gpio_watchdog);
Frans Klaverf66472d2015-01-14 09:15:36 +0100193 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
194 return ret;
195 }
René Moll66471562014-08-08 13:12:17 +0000196
Frans Klavera5f67be2015-01-14 09:15:38 +0100197 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
198 if (IS_ERR(data->gpio_kill)) {
199 ret = PTR_ERR(data->gpio_kill);
Frans Klaverf66472d2015-01-14 09:15:36 +0100200 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
Frans Klaver62113b32015-01-14 09:15:37 +0100201 return ret;
Frans Klaverf66472d2015-01-14 09:15:36 +0100202 }
203
Uwe Kleine-König9f6cd982015-05-18 22:45:07 +0200204 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
205 GPIOD_IN);
Frans Klaveree181852015-01-14 09:15:45 +0100206 if (IS_ERR(data->gpio_trigger)) {
207 /*
208 * It's not a problem if the trigger gpio isn't available, but
209 * it is worth a warning if its use was defined in the device
210 * tree.
211 */
Uwe Kleine-König9f6cd982015-05-18 22:45:07 +0200212 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
Frans Klaveree181852015-01-14 09:15:45 +0100213 data->gpio_trigger = NULL;
René Moll66471562014-08-08 13:12:17 +0000214 }
215
Frans Klaveree181852015-01-14 09:15:45 +0100216 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
217 ltc2952_poweroff_handler,
218 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
219 "ltc2952-poweroff",
220 data)) {
221 /*
222 * Some things may have happened:
223 * - No trigger input was defined
224 * - Claiming the GPIO failed
225 * - We could not map to an IRQ
226 * - We couldn't register an interrupt handler
227 *
228 * None of these really are problems, but all of them
229 * disqualify the push button from controlling the power.
230 *
231 * It is therefore important to note that if the ltc2952
232 * detects a button press for long enough, it will still start
233 * its own powerdown window and cut the power on us if we don't
234 * start the watchdog trigger.
235 */
236 if (data->gpio_trigger) {
237 dev_warn(&pdev->dev,
238 "unable to configure the trigger interrupt\n");
239 devm_gpiod_put(&pdev->dev, data->gpio_trigger);
240 data->gpio_trigger = NULL;
241 }
242 dev_info(&pdev->dev,
243 "power down trigger input will not be used\n");
244 ltc2952_poweroff_start_wde(data);
René Moll66471562014-08-08 13:12:17 +0000245 }
246
247 return 0;
René Moll66471562014-08-08 13:12:17 +0000248}
249
Frans Klaver818ca4c2015-01-14 09:15:39 +0100250static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
251 unsigned long code, void *unused)
252{
253 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
254
255 data->kernel_panic = true;
256 return NOTIFY_DONE;
257}
258
René Moll66471562014-08-08 13:12:17 +0000259static int ltc2952_poweroff_probe(struct platform_device *pdev)
260{
261 int ret;
Frans Klavera5f67be2015-01-14 09:15:38 +0100262 struct ltc2952_poweroff *data;
René Moll66471562014-08-08 13:12:17 +0000263
264 if (pm_power_off) {
265 dev_err(&pdev->dev, "pm_power_off already registered");
266 return -EBUSY;
267 }
268
Frans Klavera5f67be2015-01-14 09:15:38 +0100269 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
270 if (!data)
René Moll66471562014-08-08 13:12:17 +0000271 return -ENOMEM;
272
Frans Klavera5f67be2015-01-14 09:15:38 +0100273 data->dev = &pdev->dev;
274 platform_set_drvdata(pdev, data);
René Moll66471562014-08-08 13:12:17 +0000275
276 ret = ltc2952_poweroff_init(pdev);
277 if (ret)
Frans Klaver0a5c6a22015-01-14 09:15:34 +0100278 return ret;
René Moll66471562014-08-08 13:12:17 +0000279
Frans Klavera5f67be2015-01-14 09:15:38 +0100280 /* TODO: remove ltc2952_data */
281 ltc2952_data = data;
Frans Klaver5689b782015-01-14 09:15:42 +0100282 pm_power_off = ltc2952_poweroff_kill;
René Moll66471562014-08-08 13:12:17 +0000283
Frans Klaver818ca4c2015-01-14 09:15:39 +0100284 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
285 atomic_notifier_chain_register(&panic_notifier_list,
286 &data->panic_notifier);
René Moll66471562014-08-08 13:12:17 +0000287 dev_info(&pdev->dev, "probe successful\n");
288
289 return 0;
René Moll66471562014-08-08 13:12:17 +0000290}
291
292static int ltc2952_poweroff_remove(struct platform_device *pdev)
293{
Frans Klaver818ca4c2015-01-14 09:15:39 +0100294 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
René Moll66471562014-08-08 13:12:17 +0000295
Frans Klaver818ca4c2015-01-14 09:15:39 +0100296 pm_power_off = NULL;
Frans Klaver2f6ea8a2015-01-14 09:15:43 +0100297 hrtimer_cancel(&data->timer_trigger);
298 hrtimer_cancel(&data->timer_wde);
Frans Klaver818ca4c2015-01-14 09:15:39 +0100299 atomic_notifier_chain_unregister(&panic_notifier_list,
300 &data->panic_notifier);
René Moll66471562014-08-08 13:12:17 +0000301 return 0;
302}
303
304static const struct of_device_id of_ltc2952_poweroff_match[] = {
305 { .compatible = "lltc,ltc2952"},
306 {},
307};
308MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
309
310static struct platform_driver ltc2952_poweroff_driver = {
311 .probe = ltc2952_poweroff_probe,
312 .remove = ltc2952_poweroff_remove,
313 .driver = {
314 .name = "ltc2952-poweroff",
René Moll66471562014-08-08 13:12:17 +0000315 .of_match_table = of_ltc2952_poweroff_match,
316 },
René Moll66471562014-08-08 13:12:17 +0000317};
318
Frans Klaver818ca4c2015-01-14 09:15:39 +0100319module_platform_driver(ltc2952_poweroff_driver);
René Moll66471562014-08-08 13:12:17 +0000320
321MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
322MODULE_DESCRIPTION("LTC PowerPath power-off driver");
323MODULE_LICENSE("GPL v2");