1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * LTC2952 (PowerPath) driver
4 *
5 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
6 * Maintainer: René Moll <linux@r-moll.nl>
7 *
8 * ----------------------------------------
9 * - Description
10 * ----------------------------------------
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 triggered
14 * 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 * - GPIO
20 * ----------------------------------------
21 *
22 * The following GPIOs are used:
23 * - trigger (input)
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.
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, such
36 * that the PowerPath Control will power down the hardware.
37 *
38 * ----------------------------------------
39 * - Interrupts
40 * ----------------------------------------
41 *
42 * The driver requires a non-shared, edge-triggered interrupt on the trigger
43 * 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 should
82 * 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 callback
88 * Toggles the watchdog reset signal each wde_interval
89 *
90 * @timer: corresponding timer
91 *
92 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
93 * machine actually shuts down
94 */
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(desc: data->gpio_watchdog);
104 gpiod_set_value(desc: data->gpio_watchdog, value: !state);
105
106 hrtimer_forward_now(timer, interval: data->wde_interval);
107
108 return HRTIMER_RESTART;
109}
110
111static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
112{
113 hrtimer_start(timer: &data->timer_wde, tim: data->wde_interval, mode: HRTIMER_MODE_REL);
114}
115
116static enum hrtimer_restart
117ltc2952_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(force: true);
124
125 return HRTIMER_NORESTART;
126}
127
128/**
129 * ltc2952_poweroff_handler - Interrupt handler
130 * Triggered each time the trigger signal changes state and (de)activates a
131 * time-out (timer_trigger). Once the time-out is actually reached the shut
132 * down is executed.
133 *
134 * @irq: IRQ number
135 * @dev_id: pointer to the main data structure
136 */
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(timer: &data->timer_wde)) {
142 /* shutdown is already triggered, nothing to do any more */
143 return IRQ_HANDLED;
144 }
145
146 if (gpiod_get_value(desc: data->gpio_trigger)) {
147 hrtimer_start(timer: &data->timer_trigger, tim: data->trigger_delay,
148 mode: HRTIMER_MODE_REL);
149 } else {
150 hrtimer_cancel(timer: &data->timer_trigger);
151 }
152 return IRQ_HANDLED;
153}
154
155static void ltc2952_poweroff_kill(void)
156{
157 gpiod_set_value(desc: ltc2952_data->gpio_kill, value: 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(secs: 2, nsecs: 500L * NSEC_PER_MSEC);
164
165 hrtimer_setup(timer: &data->timer_trigger, function: ltc2952_poweroff_timer_trigger, CLOCK_MONOTONIC,
166 mode: HRTIMER_MODE_REL);
167
168 hrtimer_setup(timer: &data->timer_wde, function: ltc2952_poweroff_timer_wde, CLOCK_MONOTONIC,
169 mode: HRTIMER_MODE_REL);
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(dev: &pdev->dev, propname: "trigger-delay-ms",
181 val: &trigger_delay_ms)) {
182 data->trigger_delay = ktime_set(secs: trigger_delay_ms / MSEC_PER_SEC,
183 nsecs: (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC);
184 }
185
186 data->gpio_watchdog = devm_gpiod_get(dev: &pdev->dev, con_id: "watchdog",
187 flags: GPIOD_OUT_LOW);
188 if (IS_ERR(ptr: data->gpio_watchdog)) {
189 ret = PTR_ERR(ptr: 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(dev: &pdev->dev, con_id: "kill", flags: GPIOD_OUT_LOW);
195 if (IS_ERR(ptr: data->gpio_kill)) {
196 ret = PTR_ERR(ptr: 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(dev: &pdev->dev, con_id: "trigger",
202 flags: GPIOD_IN);
203 if (IS_ERR(ptr: data->gpio_trigger)) {
204 /*
205 * It's not a problem if the trigger gpio isn't available, but
206 * it is worth a warning if its use was defined in the device
207 * 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(dev: &pdev->dev, irq: gpiod_to_irq(desc: data->gpio_trigger),
214 handler: ltc2952_poweroff_handler,
215 irqflags: (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
216 devname: "ltc2952-poweroff",
217 dev_id: data)) {
218 /*
219 * Some things may have happened:
220 * - No trigger input was defined
221 * - Claiming the GPIO failed
222 * - We could not map to an IRQ
223 * - We couldn't register an interrupt handler
224 *
225 * None of these really are problems, but all of them
226 * disqualify the push button from controlling the power.
227 *
228 * It is therefore important to note that if the ltc2952
229 * detects a button press for long enough, it will still start
230 * its own powerdown window and cut the power on us if we don't
231 * 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(dev: &pdev->dev, desc: 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(dev: &pdev->dev, size: 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(nh: &panic_notifier_list,
283 nb: &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(timer: &data->timer_trigger);
295 hrtimer_cancel(timer: &data->timer_wde);
296 atomic_notifier_chain_unregister(nh: &panic_notifier_list,
297 nb: &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 = 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

source code of linux/drivers/power/reset/ltc2952-poweroff.c