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 struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde); 98 99 if (data->kernel_panic) 100 return HRTIMER_NORESTART; 101 102 state = gpiod_get_value(data->gpio_watchdog); 103 gpiod_set_value(data->gpio_watchdog, !state); 104 105 now = hrtimer_cb_get_time(timer); 106 hrtimer_forward(timer, now, 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 * 1E6L; 163 data->trigger_delay = ktime_set(2, 500L*1E6L); 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 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 176 177 ltc2952_poweroff_default(data); 178 179 data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", 180 GPIOD_OUT_LOW); 181 if (IS_ERR(data->gpio_watchdog)) { 182 ret = PTR_ERR(data->gpio_watchdog); 183 dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); 184 return ret; 185 } 186 187 data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW); 188 if (IS_ERR(data->gpio_kill)) { 189 ret = PTR_ERR(data->gpio_kill); 190 dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); 191 return ret; 192 } 193 194 data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger", 195 GPIOD_IN); 196 if (IS_ERR(data->gpio_trigger)) { 197 /* 198 * It's not a problem if the trigger gpio isn't available, but 199 * it is worth a warning if its use was defined in the device 200 * tree. 201 */ 202 dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); 203 data->gpio_trigger = NULL; 204 } 205 206 if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger), 207 ltc2952_poweroff_handler, 208 (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), 209 "ltc2952-poweroff", 210 data)) { 211 /* 212 * Some things may have happened: 213 * - No trigger input was defined 214 * - Claiming the GPIO failed 215 * - We could not map to an IRQ 216 * - We couldn't register an interrupt handler 217 * 218 * None of these really are problems, but all of them 219 * disqualify the push button from controlling the power. 220 * 221 * It is therefore important to note that if the ltc2952 222 * detects a button press for long enough, it will still start 223 * its own powerdown window and cut the power on us if we don't 224 * start the watchdog trigger. 225 */ 226 if (data->gpio_trigger) { 227 dev_warn(&pdev->dev, 228 "unable to configure the trigger interrupt\n"); 229 devm_gpiod_put(&pdev->dev, data->gpio_trigger); 230 data->gpio_trigger = NULL; 231 } 232 dev_info(&pdev->dev, 233 "power down trigger input will not be used\n"); 234 ltc2952_poweroff_start_wde(data); 235 } 236 237 return 0; 238 } 239 240 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb, 241 unsigned long code, void *unused) 242 { 243 struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier); 244 245 data->kernel_panic = true; 246 return NOTIFY_DONE; 247 } 248 249 static int ltc2952_poweroff_probe(struct platform_device *pdev) 250 { 251 int ret; 252 struct ltc2952_poweroff *data; 253 254 if (pm_power_off) { 255 dev_err(&pdev->dev, "pm_power_off already registered"); 256 return -EBUSY; 257 } 258 259 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 260 if (!data) 261 return -ENOMEM; 262 263 data->dev = &pdev->dev; 264 platform_set_drvdata(pdev, data); 265 266 ret = ltc2952_poweroff_init(pdev); 267 if (ret) 268 return ret; 269 270 /* TODO: remove ltc2952_data */ 271 ltc2952_data = data; 272 pm_power_off = ltc2952_poweroff_kill; 273 274 data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic; 275 atomic_notifier_chain_register(&panic_notifier_list, 276 &data->panic_notifier); 277 dev_info(&pdev->dev, "probe successful\n"); 278 279 return 0; 280 } 281 282 static int ltc2952_poweroff_remove(struct platform_device *pdev) 283 { 284 struct ltc2952_poweroff *data = platform_get_drvdata(pdev); 285 286 pm_power_off = NULL; 287 hrtimer_cancel(&data->timer_trigger); 288 hrtimer_cancel(&data->timer_wde); 289 atomic_notifier_chain_unregister(&panic_notifier_list, 290 &data->panic_notifier); 291 return 0; 292 } 293 294 static const struct of_device_id of_ltc2952_poweroff_match[] = { 295 { .compatible = "lltc,ltc2952"}, 296 {}, 297 }; 298 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); 299 300 static struct platform_driver ltc2952_poweroff_driver = { 301 .probe = ltc2952_poweroff_probe, 302 .remove = ltc2952_poweroff_remove, 303 .driver = { 304 .name = "ltc2952-poweroff", 305 .of_match_table = of_ltc2952_poweroff_match, 306 }, 307 }; 308 309 module_platform_driver(ltc2952_poweroff_driver); 310 311 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>"); 312 MODULE_DESCRIPTION("LTC PowerPath power-off driver"); 313 MODULE_LICENSE("GPL v2"); 314