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(data->gpio_watchdog); 104 gpiod_set_value(data->gpio_watchdog, !state); 105 106 hrtimer_forward_now(timer, 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(&data->timer_wde, data->wde_interval, 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(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(&data->timer_wde)) { 142 /* shutdown is already triggered, nothing to do any more */ 143 return IRQ_HANDLED; 144 } 145 146 if (gpiod_get_value(data->gpio_trigger)) { 147 hrtimer_start(&data->timer_trigger, data->trigger_delay, 148 HRTIMER_MODE_REL); 149 } else { 150 hrtimer_cancel(&data->timer_trigger); 151 } 152 return IRQ_HANDLED; 153 } 154 155 static void ltc2952_poweroff_kill(void) 156 { 157 gpiod_set_value(ltc2952_data->gpio_kill, 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(2, 500L * NSEC_PER_MSEC); 164 165 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 166 data->timer_trigger.function = ltc2952_poweroff_timer_trigger; 167 168 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, 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(&pdev->dev, "trigger-delay-ms", 181 &trigger_delay_ms)) { 182 data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC, 183 (trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC); 184 } 185 186 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", 187 GPIOD_OUT_LOW); 188 if (IS_ERR(data->gpio_watchdog)) { 189 ret = PTR_ERR(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(&pdev->dev, "kill", GPIOD_OUT_LOW); 195 if (IS_ERR(data->gpio_kill)) { 196 ret = PTR_ERR(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(&pdev->dev, "trigger", 202 GPIOD_IN); 203 if (IS_ERR(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(&pdev->dev, gpiod_to_irq(data->gpio_trigger), 214 ltc2952_poweroff_handler, 215 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 216 "ltc2952-poweroff", 217 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(&pdev->dev, 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(&pdev->dev, 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(&panic_notifier_list, 283 &data->panic_notifier); 284 dev_info(&pdev->dev, "probe successful\n"); 285 286 return 0; 287 } 288 289 static int 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(&data->timer_trigger); 295 hrtimer_cancel(&data->timer_wde); 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("René Moll <rene.moll@xsens.com>"); 319 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 320