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 | |
61 | struct 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 | */ |
84 | static 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 | */ |
95 | static 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 | |
111 | static 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 | |
116 | static enum hrtimer_restart |
117 | ltc2952_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 | */ |
137 | static 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 | |
155 | static void ltc2952_poweroff_kill(void) |
156 | { |
157 | gpiod_set_value(desc: ltc2952_data->gpio_kill, value: 1); |
158 | } |
159 | |
160 | static 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_init(timer: &data->timer_trigger, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL); |
166 | data->timer_trigger.function = ltc2952_poweroff_timer_trigger; |
167 | |
168 | hrtimer_init(timer: &data->timer_wde, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL); |
169 | data->timer_wde.function = ltc2952_poweroff_timer_wde; |
170 | } |
171 | |
172 | static 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 | |
247 | static 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 | |
256 | static 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 | |
289 | static 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 | |
300 | static const struct of_device_id of_ltc2952_poweroff_match[] = { |
301 | { .compatible = "lltc,ltc2952" }, |
302 | {}, |
303 | }; |
304 | MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); |
305 | |
306 | static struct platform_driver ltc2952_poweroff_driver = { |
307 | .probe = ltc2952_poweroff_probe, |
308 | .remove_new = ltc2952_poweroff_remove, |
309 | .driver = { |
310 | .name = "ltc2952-poweroff" , |
311 | .of_match_table = of_ltc2952_poweroff_match, |
312 | }, |
313 | }; |
314 | |
315 | module_platform_driver(ltc2952_poweroff_driver); |
316 | |
317 | MODULE_AUTHOR("René Moll <rene.moll@xsens.com>" ); |
318 | MODULE_DESCRIPTION("LTC PowerPath power-off driver" ); |
319 | |