1 /* 2 * LTC2952 (PowerPath) driver 3 * 4 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com> 5 * Maintainer: Ren� 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 35 * executed. 36 * 37 * - watchdog (output) 38 * Once a shut down is triggered, the driver will toggle this signal, 39 * with an internal (wde_interval) to stall the hardware shut down. 40 * 41 * - kill (output) 42 * The last action during shut down is triggering this signalling, such 43 * that the PowerPath Control will power down the hardware. 44 * 45 * ---------------------------------------- 46 * - Interrupts 47 * ---------------------------------------- 48 * 49 * The driver requires a non-shared, edge-triggered interrupt on the trigger 50 * GPIO. 51 * 52 */ 53 54 #include <linux/kernel.h> 55 #include <linux/init.h> 56 #include <linux/interrupt.h> 57 #include <linux/device.h> 58 #include <linux/platform_device.h> 59 #include <linux/ktime.h> 60 #include <linux/slab.h> 61 #include <linux/kmod.h> 62 #include <linux/module.h> 63 #include <linux/gpio/consumer.h> 64 #include <linux/reboot.h> 65 66 struct ltc2952_poweroff_data { 67 struct hrtimer timer_trigger; 68 struct hrtimer timer_wde; 69 70 ktime_t trigger_delay; 71 ktime_t wde_interval; 72 73 struct device *dev; 74 75 struct gpio_desc *gpio_trigger; 76 struct gpio_desc *gpio_watchdog; 77 struct gpio_desc *gpio_kill; 78 }; 79 80 static int ltc2952_poweroff_panic; 81 static struct ltc2952_poweroff_data *ltc2952_data; 82 83 /** 84 * ltc2952_poweroff_timer_wde - Timer callback 85 * Toggles the watchdog reset signal each wde_interval 86 * 87 * @timer: corresponding timer 88 * 89 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the 90 * machine actually shuts down 91 */ 92 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer) 93 { 94 ktime_t now; 95 int state; 96 unsigned long overruns; 97 98 if (ltc2952_poweroff_panic) 99 return HRTIMER_NORESTART; 100 101 state = gpiod_get_value(ltc2952_data->gpio_watchdog); 102 gpiod_set_value(ltc2952_data->gpio_watchdog, !state); 103 104 now = hrtimer_cb_get_time(timer); 105 overruns = hrtimer_forward(timer, now, ltc2952_data->wde_interval); 106 107 return HRTIMER_RESTART; 108 } 109 110 static enum hrtimer_restart ltc2952_poweroff_timer_trigger( 111 struct hrtimer *timer) 112 { 113 int ret; 114 115 ret = hrtimer_start(<c2952_data->timer_wde, 116 ltc2952_data->wde_interval, HRTIMER_MODE_REL); 117 118 if (ret) { 119 dev_err(ltc2952_data->dev, "unable to start the timer\n"); 120 /* 121 * The device will not toggle the watchdog reset, 122 * thus shut down is only safe if the PowerPath controller 123 * has a long enough time-off before triggering a hardware 124 * power-off. 125 * 126 * Only sending a warning as the system will power-off anyway 127 */ 128 } 129 130 dev_info(ltc2952_data->dev, "executing shutdown\n"); 131 132 orderly_poweroff(true); 133 134 return HRTIMER_NORESTART; 135 } 136 137 /** 138 * ltc2952_poweroff_handler - Interrupt handler 139 * Triggered each time the trigger signal changes state and (de)activates a 140 * time-out (timer_trigger). Once the time-out is actually reached the shut 141 * down is executed. 142 * 143 * @irq: IRQ number 144 * @dev_id: pointer to the main data structure 145 */ 146 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id) 147 { 148 int ret; 149 struct ltc2952_poweroff_data *data = dev_id; 150 151 if (ltc2952_poweroff_panic) 152 goto irq_ok; 153 154 if (hrtimer_active(&data->timer_wde)) { 155 /* shutdown is already triggered, nothing to do any more */ 156 goto irq_ok; 157 } 158 159 if (!hrtimer_active(&data->timer_trigger)) { 160 ret = hrtimer_start(&data->timer_trigger, data->trigger_delay, 161 HRTIMER_MODE_REL); 162 163 if (ret) 164 dev_err(data->dev, "unable to start the wait timer\n"); 165 } else { 166 ret = hrtimer_cancel(&data->timer_trigger); 167 /* omitting return value check, timer should have been valid */ 168 } 169 170 irq_ok: 171 return IRQ_HANDLED; 172 } 173 174 static void ltc2952_poweroff_kill(void) 175 { 176 gpiod_set_value(ltc2952_data->gpio_kill, 1); 177 } 178 179 static int ltc2952_poweroff_suspend(struct platform_device *pdev, 180 pm_message_t state) 181 { 182 return -ENOSYS; 183 } 184 185 static int ltc2952_poweroff_resume(struct platform_device *pdev) 186 { 187 return -ENOSYS; 188 } 189 190 static void ltc2952_poweroff_default(struct ltc2952_poweroff_data *data) 191 { 192 data->wde_interval = ktime_set(0, 300L*1E6L); 193 data->trigger_delay = ktime_set(2, 500L*1E6L); 194 195 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 196 data->timer_trigger.function = <c2952_poweroff_timer_trigger; 197 198 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 199 data->timer_wde.function = <c2952_poweroff_timer_wde; 200 } 201 202 static int ltc2952_poweroff_init(struct platform_device *pdev) 203 { 204 int ret, virq; 205 struct ltc2952_poweroff_data *data; 206 207 data = ltc2952_data; 208 ltc2952_poweroff_default(ltc2952_data); 209 210 ltc2952_data->gpio_watchdog = gpiod_get(&pdev->dev, "watchdog"); 211 if (IS_ERR(ltc2952_data->gpio_watchdog)) { 212 ret = PTR_ERR(ltc2952_data->gpio_watchdog); 213 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); 214 return ret; 215 } 216 217 ltc2952_data->gpio_kill = gpiod_get(&pdev->dev, "kill"); 218 if (IS_ERR(ltc2952_data->gpio_kill)) { 219 ret = PTR_ERR(ltc2952_data->gpio_kill); 220 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); 221 goto err_kill; 222 } 223 224 ltc2952_data->gpio_trigger = gpiod_get(&pdev->dev, "trigger"); 225 if (IS_ERR(ltc2952_data->gpio_trigger)) { 226 ret = PTR_ERR(ltc2952_data->gpio_trigger); 227 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); 228 goto err_trigger; 229 } 230 231 ret = gpiod_direction_output( 232 ltc2952_data->gpio_watchdog, 0); 233 if (ret) { 234 dev_err(&pdev->dev, "unable to use watchdog-gpio as output\n"); 235 goto err_io; 236 } 237 238 ret = gpiod_direction_output(ltc2952_data->gpio_kill, 0); 239 if (ret) { 240 dev_err(&pdev->dev, "unable to use kill-gpio as output\n"); 241 goto err_io; 242 } 243 244 virq = gpiod_to_irq(ltc2952_data->gpio_trigger); 245 if (virq < 0) { 246 dev_err(&pdev->dev, "cannot map GPIO as interrupt"); 247 goto err_io; 248 } 249 250 ret = devm_request_irq(&pdev->dev, virq, 251 ltc2952_poweroff_handler, 252 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 253 "ltc2952-poweroff", 254 ltc2952_data); 255 256 if (ret) { 257 dev_err(&pdev->dev, "cannot configure an interrupt handler\n"); 258 goto err_io; 259 } 260 261 return 0; 262 263 err_io: 264 gpiod_put(ltc2952_data->gpio_trigger); 265 err_trigger: 266 gpiod_put(ltc2952_data->gpio_kill); 267 err_kill: 268 gpiod_put(ltc2952_data->gpio_watchdog); 269 270 return ret; 271 } 272 273 static int ltc2952_poweroff_probe(struct platform_device *pdev) 274 { 275 int ret; 276 277 if (pm_power_off) { 278 dev_err(&pdev->dev, "pm_power_off already registered"); 279 return -EBUSY; 280 } 281 282 ltc2952_data = devm_kzalloc(&pdev->dev, sizeof(*ltc2952_data), 283 GFP_KERNEL); 284 if (!ltc2952_data) 285 return -ENOMEM; 286 287 ltc2952_data->dev = &pdev->dev; 288 289 ret = ltc2952_poweroff_init(pdev); 290 if (ret) 291 return ret; 292 293 pm_power_off = <c2952_poweroff_kill; 294 295 dev_info(&pdev->dev, "probe successful\n"); 296 297 return 0; 298 } 299 300 static int ltc2952_poweroff_remove(struct platform_device *pdev) 301 { 302 pm_power_off = NULL; 303 304 if (ltc2952_data) { 305 gpiod_put(ltc2952_data->gpio_trigger); 306 gpiod_put(ltc2952_data->gpio_watchdog); 307 gpiod_put(ltc2952_data->gpio_kill); 308 } 309 return 0; 310 } 311 312 static const struct of_device_id of_ltc2952_poweroff_match[] = { 313 { .compatible = "lltc,ltc2952"}, 314 {}, 315 }; 316 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); 317 318 static struct platform_driver ltc2952_poweroff_driver = { 319 .probe = ltc2952_poweroff_probe, 320 .remove = ltc2952_poweroff_remove, 321 .driver = { 322 .name = "ltc2952-poweroff", 323 .of_match_table = of_ltc2952_poweroff_match, 324 }, 325 .suspend = ltc2952_poweroff_suspend, 326 .resume = ltc2952_poweroff_resume, 327 }; 328 329 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb, 330 unsigned long code, void *unused) 331 { 332 ltc2952_poweroff_panic = 1; 333 return NOTIFY_DONE; 334 } 335 336 static struct notifier_block ltc2952_poweroff_panic_nb = { 337 .notifier_call = ltc2952_poweroff_notify_panic, 338 }; 339 340 static int __init ltc2952_poweroff_platform_init(void) 341 { 342 ltc2952_poweroff_panic = 0; 343 344 atomic_notifier_chain_register(&panic_notifier_list, 345 <c2952_poweroff_panic_nb); 346 347 return platform_driver_register(<c2952_poweroff_driver); 348 } 349 350 static void __exit ltc2952_poweroff_platform_exit(void) 351 { 352 atomic_notifier_chain_unregister(&panic_notifier_list, 353 <c2952_poweroff_panic_nb); 354 355 platform_driver_unregister(<c2952_poweroff_driver); 356 } 357 358 module_init(ltc2952_poweroff_platform_init); 359 module_exit(ltc2952_poweroff_platform_exit); 360 361 MODULE_AUTHOR("Ren� Moll <rene.moll@xsens.com>"); 362 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 363 MODULE_LICENSE("GPL v2"); 364