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/mod_devicetable.h>
56 #include <linux/gpio/consumer.h>
57 #include <linux/reboot.h>
58
59 struct ltc2952_poweroff {
60 struct hrtimer timer_trigger;
61 struct hrtimer timer_wde;
62
63 ktime_t trigger_delay;
64 ktime_t wde_interval;
65
66 struct device *dev;
67
68 struct gpio_desc *gpio_trigger;
69 struct gpio_desc *gpio_watchdog;
70 struct gpio_desc *gpio_kill;
71
72 bool kernel_panic;
73 struct notifier_block panic_notifier;
74 };
75
76 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
77
78 /*
79 * This global variable is only needed for pm_power_off. We should
80 * remove it entirely once we don't need the global state anymore.
81 */
82 static struct ltc2952_poweroff *ltc2952_data;
83
84 /**
85 * ltc2952_poweroff_timer_wde - Timer callback
86 * Toggles the watchdog reset signal each wde_interval
87 *
88 * @timer: corresponding timer
89 *
90 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
91 * machine actually shuts down
92 */
ltc2952_poweroff_timer_wde(struct hrtimer * timer)93 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
94 {
95 ktime_t now;
96 int state;
97 unsigned long overruns;
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 now = hrtimer_cb_get_time(timer);
107 overruns = hrtimer_forward(timer, now, data->wde_interval);
108
109 return HRTIMER_RESTART;
110 }
111
ltc2952_poweroff_start_wde(struct ltc2952_poweroff * data)112 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
113 {
114 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
115 }
116
117 static enum hrtimer_restart
ltc2952_poweroff_timer_trigger(struct hrtimer * timer)118 ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
119 {
120 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
121
122 ltc2952_poweroff_start_wde(data);
123 dev_info(data->dev, "executing shutdown\n");
124 orderly_poweroff(true);
125
126 return HRTIMER_NORESTART;
127 }
128
129 /**
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
133 * down is executed.
134 *
135 * @irq: IRQ number
136 * @dev_id: pointer to the main data structure
137 */
ltc2952_poweroff_handler(int irq,void * dev_id)138 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
139 {
140 struct ltc2952_poweroff *data = dev_id;
141
142 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
143 /* shutdown is already triggered, nothing to do any more */
144 return IRQ_HANDLED;
145 }
146
147 if (gpiod_get_value(data->gpio_trigger)) {
148 hrtimer_start(&data->timer_trigger, data->trigger_delay,
149 HRTIMER_MODE_REL);
150 } else {
151 hrtimer_cancel(&data->timer_trigger);
152 }
153 return IRQ_HANDLED;
154 }
155
ltc2952_poweroff_kill(void)156 static void ltc2952_poweroff_kill(void)
157 {
158 gpiod_set_value(ltc2952_data->gpio_kill, 1);
159 }
160
ltc2952_poweroff_default(struct ltc2952_poweroff * data)161 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
162 {
163 data->wde_interval = 300L * 1E6L;
164 data->trigger_delay = ktime_set(2, 500L*1E6L);
165
166 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
167 data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
168
169 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
170 data->timer_wde.function = ltc2952_poweroff_timer_wde;
171 }
172
ltc2952_poweroff_init(struct platform_device * pdev)173 static int ltc2952_poweroff_init(struct platform_device *pdev)
174 {
175 int ret;
176 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
177
178 ltc2952_poweroff_default(data);
179
180 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
181 GPIOD_OUT_LOW);
182 if (IS_ERR(data->gpio_watchdog)) {
183 ret = PTR_ERR(data->gpio_watchdog);
184 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
185 return ret;
186 }
187
188 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
189 if (IS_ERR(data->gpio_kill)) {
190 ret = PTR_ERR(data->gpio_kill);
191 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
192 return ret;
193 }
194
195 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
196 GPIOD_IN);
197 if (IS_ERR(data->gpio_trigger)) {
198 /*
199 * It's not a problem if the trigger gpio isn't available, but
200 * it is worth a warning if its use was defined in the device
201 * tree.
202 */
203 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
204 data->gpio_trigger = NULL;
205 }
206
207 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
208 ltc2952_poweroff_handler,
209 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
210 "ltc2952-poweroff",
211 data)) {
212 /*
213 * Some things may have happened:
214 * - No trigger input was defined
215 * - Claiming the GPIO failed
216 * - We could not map to an IRQ
217 * - We couldn't register an interrupt handler
218 *
219 * None of these really are problems, but all of them
220 * disqualify the push button from controlling the power.
221 *
222 * It is therefore important to note that if the ltc2952
223 * detects a button press for long enough, it will still start
224 * its own powerdown window and cut the power on us if we don't
225 * start the watchdog trigger.
226 */
227 if (data->gpio_trigger) {
228 dev_warn(&pdev->dev,
229 "unable to configure the trigger interrupt\n");
230 devm_gpiod_put(&pdev->dev, data->gpio_trigger);
231 data->gpio_trigger = NULL;
232 }
233 dev_info(&pdev->dev,
234 "power down trigger input will not be used\n");
235 ltc2952_poweroff_start_wde(data);
236 }
237
238 return 0;
239 }
240
ltc2952_poweroff_notify_panic(struct notifier_block * nb,unsigned long code,void * unused)241 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
242 unsigned long code, void *unused)
243 {
244 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
245
246 data->kernel_panic = true;
247 return NOTIFY_DONE;
248 }
249
ltc2952_poweroff_probe(struct platform_device * pdev)250 static int ltc2952_poweroff_probe(struct platform_device *pdev)
251 {
252 int ret;
253 struct ltc2952_poweroff *data;
254
255 if (pm_power_off) {
256 dev_err(&pdev->dev, "pm_power_off already registered");
257 return -EBUSY;
258 }
259
260 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
261 if (!data)
262 return -ENOMEM;
263
264 data->dev = &pdev->dev;
265 platform_set_drvdata(pdev, data);
266
267 ret = ltc2952_poweroff_init(pdev);
268 if (ret)
269 return ret;
270
271 /* TODO: remove ltc2952_data */
272 ltc2952_data = data;
273 pm_power_off = ltc2952_poweroff_kill;
274
275 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
276 atomic_notifier_chain_register(&panic_notifier_list,
277 &data->panic_notifier);
278 dev_info(&pdev->dev, "probe successful\n");
279
280 return 0;
281 }
282
ltc2952_poweroff_remove(struct platform_device * pdev)283 static int ltc2952_poweroff_remove(struct platform_device *pdev)
284 {
285 struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
286
287 pm_power_off = NULL;
288 hrtimer_cancel(&data->timer_trigger);
289 hrtimer_cancel(&data->timer_wde);
290 atomic_notifier_chain_unregister(&panic_notifier_list,
291 &data->panic_notifier);
292 return 0;
293 }
294
295 static const struct of_device_id of_ltc2952_poweroff_match[] = {
296 { .compatible = "lltc,ltc2952"},
297 {},
298 };
299 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
300
301 static struct platform_driver ltc2952_poweroff_driver = {
302 .probe = ltc2952_poweroff_probe,
303 .remove = ltc2952_poweroff_remove,
304 .driver = {
305 .name = "ltc2952-poweroff",
306 .of_match_table = of_ltc2952_poweroff_match,
307 },
308 };
309
310 module_platform_driver(ltc2952_poweroff_driver);
311
312 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
313 MODULE_DESCRIPTION("LTC PowerPath power-off driver");
314 MODULE_LICENSE("GPL v2");
315