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 ktime_t now; 98 int state; 99 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde); 100 101 if (data->kernel_panic) 102 return HRTIMER_NORESTART; 103 104 state = gpiod_get_value(data->gpio_watchdog); 105 gpiod_set_value(data->gpio_watchdog, !state); 106 107 now = hrtimer_cb_get_time(timer); 108 hrtimer_forward(timer, now, data->wde_interval); 109 110 return HRTIMER_RESTART; 111 } 112 113 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data) 114 { 115 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL); 116 } 117 118 static enum hrtimer_restart 119 ltc2952_poweroff_timer_trigger(struct hrtimer *timer) 120 { 121 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger); 122 123 ltc2952_poweroff_start_wde(data); 124 dev_info(data->dev, "executing shutdown\n"); 125 orderly_poweroff(true); 126 127 return HRTIMER_NORESTART; 128 } 129 130 /** 131 * ltc2952_poweroff_handler - Interrupt handler 132 * Triggered each time the trigger signal changes state and (de)activates a 133 * time-out (timer_trigger). Once the time-out is actually reached the shut 134 * down is executed. 135 * 136 * @irq: IRQ number 137 * @dev_id: pointer to the main data structure 138 */ 139 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id) 140 { 141 struct ltc2952_poweroff *data = dev_id; 142 143 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) { 144 /* shutdown is already triggered, nothing to do any more */ 145 return IRQ_HANDLED; 146 } 147 148 if (gpiod_get_value(data->gpio_trigger)) { 149 hrtimer_start(&data->timer_trigger, data->trigger_delay, 150 HRTIMER_MODE_REL); 151 } else { 152 hrtimer_cancel(&data->timer_trigger); 153 } 154 return IRQ_HANDLED; 155 } 156 157 static void ltc2952_poweroff_kill(void) 158 { 159 gpiod_set_value(ltc2952_data->gpio_kill, 1); 160 } 161 162 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data) 163 { 164 data->wde_interval = 300L * 1E6L; 165 data->trigger_delay = ktime_set(2, 500L*1E6L); 166 167 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 168 data->timer_trigger.function = ltc2952_poweroff_timer_trigger; 169 170 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 171 data->timer_wde.function = ltc2952_poweroff_timer_wde; 172 } 173 174 static int ltc2952_poweroff_init(struct platform_device *pdev) 175 { 176 int ret; 177 u32 trigger_delay_ms; 178 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 179 180 ltc2952_poweroff_default(data); 181 182 if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms", 183 &trigger_delay_ms)) { 184 data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC, 185 (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC); 186 } 187 188 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", 189 GPIOD_OUT_LOW); 190 if (IS_ERR(data->gpio_watchdog)) { 191 ret = PTR_ERR(data->gpio_watchdog); 192 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); 193 return ret; 194 } 195 196 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW); 197 if (IS_ERR(data->gpio_kill)) { 198 ret = PTR_ERR(data->gpio_kill); 199 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); 200 return ret; 201 } 202 203 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger", 204 GPIOD_IN); 205 if (IS_ERR(data->gpio_trigger)) { 206 /* 207 * It's not a problem if the trigger gpio isn't available, but 208 * it is worth a warning if its use was defined in the device 209 * tree. 210 */ 211 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); 212 data->gpio_trigger = NULL; 213 } 214 215 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger), 216 ltc2952_poweroff_handler, 217 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 218 "ltc2952-poweroff", 219 data)) { 220 /* 221 * Some things may have happened: 222 * - No trigger input was defined 223 * - Claiming the GPIO failed 224 * - We could not map to an IRQ 225 * - We couldn't register an interrupt handler 226 * 227 * None of these really are problems, but all of them 228 * disqualify the push button from controlling the power. 229 * 230 * It is therefore important to note that if the ltc2952 231 * detects a button press for long enough, it will still start 232 * its own powerdown window and cut the power on us if we don't 233 * start the watchdog trigger. 234 */ 235 if (data->gpio_trigger) { 236 dev_warn(&pdev->dev, 237 "unable to configure the trigger interrupt\n"); 238 devm_gpiod_put(&pdev->dev, data->gpio_trigger); 239 data->gpio_trigger = NULL; 240 } 241 dev_info(&pdev->dev, 242 "power down trigger input will not be used\n"); 243 ltc2952_poweroff_start_wde(data); 244 } 245 246 return 0; 247 } 248 249 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb, 250 unsigned long code, void *unused) 251 { 252 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier); 253 254 data->kernel_panic = true; 255 return NOTIFY_DONE; 256 } 257 258 static int ltc2952_poweroff_probe(struct platform_device *pdev) 259 { 260 int ret; 261 struct ltc2952_poweroff *data; 262 263 if (pm_power_off) { 264 dev_err(&pdev->dev, "pm_power_off already registered"); 265 return -EBUSY; 266 } 267 268 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 269 if (!data) 270 return -ENOMEM; 271 272 data->dev = &pdev->dev; 273 platform_set_drvdata(pdev, data); 274 275 ret = ltc2952_poweroff_init(pdev); 276 if (ret) 277 return ret; 278 279 /* TODO: remove ltc2952_data */ 280 ltc2952_data = data; 281 pm_power_off = ltc2952_poweroff_kill; 282 283 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic; 284 atomic_notifier_chain_register(&panic_notifier_list, 285 &data->panic_notifier); 286 dev_info(&pdev->dev, "probe successful\n"); 287 288 return 0; 289 } 290 291 static int ltc2952_poweroff_remove(struct platform_device *pdev) 292 { 293 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 294 295 pm_power_off = NULL; 296 hrtimer_cancel(&data->timer_trigger); 297 hrtimer_cancel(&data->timer_wde); 298 atomic_notifier_chain_unregister(&panic_notifier_list, 299 &data->panic_notifier); 300 return 0; 301 } 302 303 static const struct of_device_id of_ltc2952_poweroff_match[] = { 304 { .compatible = "lltc,ltc2952"}, 305 {}, 306 }; 307 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); 308 309 static struct platform_driver ltc2952_poweroff_driver = { 310 .probe = ltc2952_poweroff_probe, 311 .remove = ltc2952_poweroff_remove, 312 .driver = { 313 .name = "ltc2952-poweroff", 314 .of_match_table = of_ltc2952_poweroff_match, 315 }, 316 }; 317 318 module_platform_driver(ltc2952_poweroff_driver); 319 320 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>"); 321 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 322 MODULE_LICENSE("GPL v2"); 323