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/mod_devicetable.h> 56 #include <linux/gpio/consumer.h> 57 #include <linux/reboot.h> 58 59 struct ltc2952_poweroff { 60 struct hrtimer timer_trigger; 61 struct hrtimer timer_wde; 62 63 ktime_t trigger_delay; 64 ktime_t wde_interval; 65 66 struct device *dev; 67 68 struct gpio_desc *gpio_trigger; 69 struct gpio_desc *gpio_watchdog; 70 struct gpio_desc *gpio_kill; 71 72 bool kernel_panic; 73 struct notifier_block panic_notifier; 74 }; 75 76 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m) 77 78 /* 79 * This global variable is only needed for pm_power_off. We should 80 * remove it entirely once we don't need the global state anymore. 81 */ 82 static struct ltc2952_poweroff *ltc2952_data; 83 84 /** 85 * ltc2952_poweroff_timer_wde - Timer callback 86 * Toggles the watchdog reset signal each wde_interval 87 * 88 * @timer: corresponding timer 89 * 90 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the 91 * machine actually shuts down 92 */ 93 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer) 94 { 95 ktime_t now; 96 int state; 97 unsigned long overruns; 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 now = hrtimer_cb_get_time(timer); 107 overruns = hrtimer_forward(timer, now, data->wde_interval); 108 109 return HRTIMER_RESTART; 110 } 111 112 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data) 113 { 114 hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL); 115 } 116 117 static enum hrtimer_restart 118 ltc2952_poweroff_timer_trigger(struct hrtimer *timer) 119 { 120 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger); 121 122 ltc2952_poweroff_start_wde(data); 123 dev_info(data->dev, "executing shutdown\n"); 124 orderly_poweroff(true); 125 126 return HRTIMER_NORESTART; 127 } 128 129 /** 130 * ltc2952_poweroff_handler - Interrupt handler 131 * Triggered each time the trigger signal changes state and (de)activates a 132 * time-out (timer_trigger). Once the time-out is actually reached the shut 133 * down is executed. 134 * 135 * @irq: IRQ number 136 * @dev_id: pointer to the main data structure 137 */ 138 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id) 139 { 140 struct ltc2952_poweroff *data = dev_id; 141 142 if (data->kernel_panic || hrtimer_active(&data->timer_wde)) { 143 /* shutdown is already triggered, nothing to do any more */ 144 return IRQ_HANDLED; 145 } 146 147 if (gpiod_get_value(data->gpio_trigger)) { 148 hrtimer_start(&data->timer_trigger, data->trigger_delay, 149 HRTIMER_MODE_REL); 150 } else { 151 hrtimer_cancel(&data->timer_trigger); 152 } 153 return IRQ_HANDLED; 154 } 155 156 static void ltc2952_poweroff_kill(void) 157 { 158 gpiod_set_value(ltc2952_data->gpio_kill, 1); 159 } 160 161 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data) 162 { 163 data->wde_interval = 300L * 1E6L; 164 data->trigger_delay = ktime_set(2, 500L*1E6L); 165 166 hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 167 data->timer_trigger.function = ltc2952_poweroff_timer_trigger; 168 169 hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 170 data->timer_wde.function = ltc2952_poweroff_timer_wde; 171 } 172 173 static int ltc2952_poweroff_init(struct platform_device *pdev) 174 { 175 int ret; 176 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 177 178 ltc2952_poweroff_default(data); 179 180 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", 181 GPIOD_OUT_LOW); 182 if (IS_ERR(data->gpio_watchdog)) { 183 ret = PTR_ERR(data->gpio_watchdog); 184 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); 185 return ret; 186 } 187 188 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW); 189 if (IS_ERR(data->gpio_kill)) { 190 ret = PTR_ERR(data->gpio_kill); 191 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); 192 return ret; 193 } 194 195 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger", 196 GPIOD_IN); 197 if (IS_ERR(data->gpio_trigger)) { 198 /* 199 * It's not a problem if the trigger gpio isn't available, but 200 * it is worth a warning if its use was defined in the device 201 * tree. 202 */ 203 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); 204 data->gpio_trigger = NULL; 205 } 206 207 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger), 208 ltc2952_poweroff_handler, 209 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 210 "ltc2952-poweroff", 211 data)) { 212 /* 213 * Some things may have happened: 214 * - No trigger input was defined 215 * - Claiming the GPIO failed 216 * - We could not map to an IRQ 217 * - We couldn't register an interrupt handler 218 * 219 * None of these really are problems, but all of them 220 * disqualify the push button from controlling the power. 221 * 222 * It is therefore important to note that if the ltc2952 223 * detects a button press for long enough, it will still start 224 * its own powerdown window and cut the power on us if we don't 225 * start the watchdog trigger. 226 */ 227 if (data->gpio_trigger) { 228 dev_warn(&pdev->dev, 229 "unable to configure the trigger interrupt\n"); 230 devm_gpiod_put(&pdev->dev, data->gpio_trigger); 231 data->gpio_trigger = NULL; 232 } 233 dev_info(&pdev->dev, 234 "power down trigger input will not be used\n"); 235 ltc2952_poweroff_start_wde(data); 236 } 237 238 return 0; 239 } 240 241 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb, 242 unsigned long code, void *unused) 243 { 244 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier); 245 246 data->kernel_panic = true; 247 return NOTIFY_DONE; 248 } 249 250 static int ltc2952_poweroff_probe(struct platform_device *pdev) 251 { 252 int ret; 253 struct ltc2952_poweroff *data; 254 255 if (pm_power_off) { 256 dev_err(&pdev->dev, "pm_power_off already registered"); 257 return -EBUSY; 258 } 259 260 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 261 if (!data) 262 return -ENOMEM; 263 264 data->dev = &pdev->dev; 265 platform_set_drvdata(pdev, data); 266 267 ret = ltc2952_poweroff_init(pdev); 268 if (ret) 269 return ret; 270 271 /* TODO: remove ltc2952_data */ 272 ltc2952_data = data; 273 pm_power_off = ltc2952_poweroff_kill; 274 275 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic; 276 atomic_notifier_chain_register(&panic_notifier_list, 277 &data->panic_notifier); 278 dev_info(&pdev->dev, "probe successful\n"); 279 280 return 0; 281 } 282 283 static int ltc2952_poweroff_remove(struct platform_device *pdev) 284 { 285 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 286 287 pm_power_off = NULL; 288 hrtimer_cancel(&data->timer_trigger); 289 hrtimer_cancel(&data->timer_wde); 290 atomic_notifier_chain_unregister(&panic_notifier_list, 291 &data->panic_notifier); 292 return 0; 293 } 294 295 static const struct of_device_id of_ltc2952_poweroff_match[] = { 296 { .compatible = "lltc,ltc2952"}, 297 {}, 298 }; 299 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); 300 301 static struct platform_driver ltc2952_poweroff_driver = { 302 .probe = ltc2952_poweroff_probe, 303 .remove = ltc2952_poweroff_remove, 304 .driver = { 305 .name = "ltc2952-poweroff", 306 .of_match_table = of_ltc2952_poweroff_match, 307 }, 308 }; 309 310 module_platform_driver(ltc2952_poweroff_driver); 311 312 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>"); 313 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 314 MODULE_LICENSE("GPL v2"); 315