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 { 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 bool kernel_panic; 80 struct notifier_block panic_notifier; 81 }; 82 83 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m) 84 85 /* 86 * This global variable is only needed for pm_power_off. We should 87 * remove it entirely once we don't need the global state anymore. 88 */ 89 static struct ltc2952_poweroff *ltc2952_data; 90 91 /** 92 * ltc2952_poweroff_timer_wde - Timer callback 93 * Toggles the watchdog reset signal each wde_interval 94 * 95 * @timer: corresponding timer 96 * 97 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the 98 * machine actually shuts down 99 */ 100 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer) 101 { 102 ktime_t now; 103 int state; 104 unsigned long overruns; 105 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde); 106 107 if (data->kernel_panic) 108 return HRTIMER_NORESTART; 109 110 state = gpiod_get_value(data->gpio_watchdog); 111 gpiod_set_value(data->gpio_watchdog, !state); 112 113 now = hrtimer_cb_get_time(timer); 114 overruns = hrtimer_forward(timer, now, data->wde_interval); 115 116 return HRTIMER_RESTART; 117 } 118 119 static enum hrtimer_restart 120 ltc2952_poweroff_timer_trigger(struct hrtimer *timer) 121 { 122 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger); 123 int ret = hrtimer_start(&data->timer_wde, 124 data->wde_interval, HRTIMER_MODE_REL); 125 126 if (ret) { 127 dev_err(data->dev, "unable to start the timer\n"); 128 /* 129 * The device will not toggle the watchdog reset, 130 * thus shut down is only safe if the PowerPath controller 131 * has a long enough time-off before triggering a hardware 132 * power-off. 133 * 134 * Only sending a warning as the system will power-off anyway 135 */ 136 } 137 138 dev_info(data->dev, "executing shutdown\n"); 139 140 orderly_poweroff(true); 141 142 return HRTIMER_NORESTART; 143 } 144 145 /** 146 * ltc2952_poweroff_handler - Interrupt handler 147 * Triggered each time the trigger signal changes state and (de)activates a 148 * time-out (timer_trigger). Once the time-out is actually reached the shut 149 * down is executed. 150 * 151 * @irq: IRQ number 152 * @dev_id: pointer to the main data structure 153 */ 154 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id) 155 { 156 int ret; 157 struct ltc2952_poweroff *data = dev_id; 158 159 if (data->kernel_panic) 160 goto irq_ok; 161 162 if (hrtimer_active(&data->timer_wde)) { 163 /* shutdown is already triggered, nothing to do any more */ 164 goto irq_ok; 165 } 166 167 if (!hrtimer_active(&data->timer_trigger)) { 168 ret = hrtimer_start(&data->timer_trigger, data->trigger_delay, 169 HRTIMER_MODE_REL); 170 171 if (ret) 172 dev_err(data->dev, "unable to start the wait timer\n"); 173 } else { 174 ret = hrtimer_cancel(&data->timer_trigger); 175 /* omitting return value check, timer should have been valid */ 176 } 177 178 irq_ok: 179 return IRQ_HANDLED; 180 } 181 182 static void ltc2952_poweroff_kill(void) 183 { 184 gpiod_set_value(ltc2952_data->gpio_kill, 1); 185 } 186 187 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data) 188 { 189 data->wde_interval = ktime_set(0, 300L*1E6L); 190 data->trigger_delay = ktime_set(2, 500L*1E6L); 191 192 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 193 data->timer_trigger.function = <c2952_poweroff_timer_trigger; 194 195 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 196 data->timer_wde.function = <c2952_poweroff_timer_wde; 197 } 198 199 static int ltc2952_poweroff_init(struct platform_device *pdev) 200 { 201 int ret, virq; 202 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 203 204 ltc2952_poweroff_default(data); 205 206 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", 207 GPIOD_OUT_LOW); 208 if (IS_ERR(data->gpio_watchdog)) { 209 ret = PTR_ERR(data->gpio_watchdog); 210 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); 211 return ret; 212 } 213 214 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW); 215 if (IS_ERR(data->gpio_kill)) { 216 ret = PTR_ERR(data->gpio_kill); 217 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); 218 return ret; 219 } 220 221 data->gpio_trigger = devm_gpiod_get(&pdev->dev, "trigger", 222 GPIOD_IN); 223 if (IS_ERR(ltc2952_data->gpio_trigger)) { 224 ret = PTR_ERR(ltc2952_data->gpio_trigger); 225 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); 226 return ret; 227 } 228 229 virq = gpiod_to_irq(data->gpio_trigger); 230 if (virq < 0) { 231 dev_err(&pdev->dev, "cannot map GPIO as interrupt"); 232 return ret; 233 } 234 235 ret = devm_request_irq(&pdev->dev, virq, 236 ltc2952_poweroff_handler, 237 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 238 "ltc2952-poweroff", 239 data); 240 241 if (ret) { 242 dev_err(&pdev->dev, "cannot configure an interrupt handler\n"); 243 return ret; 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 = <c2952_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 atomic_notifier_chain_unregister(&panic_notifier_list, 297 &data->panic_notifier); 298 return 0; 299 } 300 301 static const struct of_device_id of_ltc2952_poweroff_match[] = { 302 { .compatible = "lltc,ltc2952"}, 303 {}, 304 }; 305 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); 306 307 static struct platform_driver ltc2952_poweroff_driver = { 308 .probe = ltc2952_poweroff_probe, 309 .remove = ltc2952_poweroff_remove, 310 .driver = { 311 .name = "ltc2952-poweroff", 312 .of_match_table = of_ltc2952_poweroff_match, 313 }, 314 }; 315 316 module_platform_driver(ltc2952_poweroff_driver); 317 318 MODULE_AUTHOR("Ren� Moll <rene.moll@xsens.com>"); 319 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 320 MODULE_LICENSE("GPL v2"); 321