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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 | /* * LTC2952 (PowerPath) driver * * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com> * Maintainer: René Moll <linux@r-moll.nl> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * ---------------------------------------- * - Description * ---------------------------------------- * * This driver is to be used with an external PowerPath Controller (LTC2952). * Its function is to determine when a external shut down is triggered * and react by properly shutting down the system. * * This driver expects a device tree with a ltc2952 entry for pin mapping. * * ---------------------------------------- * - GPIO * ---------------------------------------- * * The following GPIOs are used: * - trigger (input) * A level change indicates the shut-down trigger. If it's state reverts * within the time-out defined by trigger_delay, the shut down is not * executed. If no pin is assigned to this input, the driver will start the * watchdog toggle immediately. The chip will only power off the system if * it is requested to do so through the kill line. * * - watchdog (output) * Once a shut down is triggered, the driver will toggle this signal, * with an internal (wde_interval) to stall the hardware shut down. * * - kill (output) * The last action during shut down is triggering this signalling, such * that the PowerPath Control will power down the hardware. * * ---------------------------------------- * - Interrupts * ---------------------------------------- * * The driver requires a non-shared, edge-triggered interrupt on the trigger * GPIO. * */ #include <linux/kernel.h> #include <linux/init.h> #include <linux/interrupt.h> #include <linux/device.h> #include <linux/platform_device.h> #include <linux/ktime.h> #include <linux/slab.h> #include <linux/kmod.h> #include <linux/module.h> #include <linux/gpio/consumer.h> #include <linux/reboot.h> struct ltc2952_poweroff { struct hrtimer timer_trigger; struct hrtimer timer_wde; ktime_t trigger_delay; ktime_t wde_interval; struct device *dev; struct gpio_desc *gpio_trigger; struct gpio_desc *gpio_watchdog; struct gpio_desc *gpio_kill; bool kernel_panic; struct notifier_block panic_notifier; }; #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m) /* * This global variable is only needed for pm_power_off. We should * remove it entirely once we don't need the global state anymore. */ static struct ltc2952_poweroff *ltc2952_data; /** * ltc2952_poweroff_timer_wde - Timer callback * Toggles the watchdog reset signal each wde_interval * * @timer: corresponding timer * * Returns HRTIMER_RESTART for an infinite loop which will only stop when the * machine actually shuts down */ static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer) { ktime_t now; int state; unsigned long overruns; struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde); if (data->kernel_panic) return HRTIMER_NORESTART; state = gpiod_get_value(data->gpio_watchdog); gpiod_set_value(data->gpio_watchdog, !state); now = hrtimer_cb_get_time(timer); overruns = hrtimer_forward(timer, now, data->wde_interval); return HRTIMER_RESTART; } static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data) { hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL); } static enum hrtimer_restart ltc2952_poweroff_timer_trigger(struct hrtimer *timer) { struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger); ltc2952_poweroff_start_wde(data); dev_info(data->dev, "executing shutdown\n"); orderly_poweroff(true); return HRTIMER_NORESTART; } /** * ltc2952_poweroff_handler - Interrupt handler * Triggered each time the trigger signal changes state and (de)activates a * time-out (timer_trigger). Once the time-out is actually reached the shut * down is executed. * * @irq: IRQ number * @dev_id: pointer to the main data structure */ static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id) { struct ltc2952_poweroff *data = dev_id; if (data->kernel_panic || hrtimer_active(&data->timer_wde)) { /* shutdown is already triggered, nothing to do any more */ return IRQ_HANDLED; } if (gpiod_get_value(data->gpio_trigger)) { hrtimer_start(&data->timer_trigger, data->trigger_delay, HRTIMER_MODE_REL); } else { hrtimer_cancel(&data->timer_trigger); } return IRQ_HANDLED; } static void ltc2952_poweroff_kill(void) { gpiod_set_value(ltc2952_data->gpio_kill, 1); } static void ltc2952_poweroff_default(struct ltc2952_poweroff *data) { data->wde_interval = ktime_set(0, 300L*1E6L); data->trigger_delay = ktime_set(2, 500L*1E6L); hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL); data->timer_trigger.function = ltc2952_poweroff_timer_trigger; hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL); data->timer_wde.function = ltc2952_poweroff_timer_wde; } static int ltc2952_poweroff_init(struct platform_device *pdev) { int ret; struct ltc2952_poweroff *data = platform_get_drvdata(pdev); ltc2952_poweroff_default(data); data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog", GPIOD_OUT_LOW); if (IS_ERR(data->gpio_watchdog)) { ret = PTR_ERR(data->gpio_watchdog); dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n"); return ret; } data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW); if (IS_ERR(data->gpio_kill)) { ret = PTR_ERR(data->gpio_kill); dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n"); return ret; } data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger", GPIOD_IN); if (IS_ERR(data->gpio_trigger)) { /* * It's not a problem if the trigger gpio isn't available, but * it is worth a warning if its use was defined in the device * tree. */ dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n"); data->gpio_trigger = NULL; } if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger), ltc2952_poweroff_handler, (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING), "ltc2952-poweroff", data)) { /* * Some things may have happened: * - No trigger input was defined * - Claiming the GPIO failed * - We could not map to an IRQ * - We couldn't register an interrupt handler * * None of these really are problems, but all of them * disqualify the push button from controlling the power. * * It is therefore important to note that if the ltc2952 * detects a button press for long enough, it will still start * its own powerdown window and cut the power on us if we don't * start the watchdog trigger. */ if (data->gpio_trigger) { dev_warn(&pdev->dev, "unable to configure the trigger interrupt\n"); devm_gpiod_put(&pdev->dev, data->gpio_trigger); data->gpio_trigger = NULL; } dev_info(&pdev->dev, "power down trigger input will not be used\n"); ltc2952_poweroff_start_wde(data); } return 0; } static int ltc2952_poweroff_notify_panic(struct notifier_block *nb, unsigned long code, void *unused) { struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier); data->kernel_panic = true; return NOTIFY_DONE; } static int ltc2952_poweroff_probe(struct platform_device *pdev) { int ret; struct ltc2952_poweroff *data; if (pm_power_off) { dev_err(&pdev->dev, "pm_power_off already registered"); return -EBUSY; } data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->dev = &pdev->dev; platform_set_drvdata(pdev, data); ret = ltc2952_poweroff_init(pdev); if (ret) return ret; /* TODO: remove ltc2952_data */ ltc2952_data = data; pm_power_off = ltc2952_poweroff_kill; data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic; atomic_notifier_chain_register(&panic_notifier_list, &data->panic_notifier); dev_info(&pdev->dev, "probe successful\n"); return 0; } static int ltc2952_poweroff_remove(struct platform_device *pdev) { struct ltc2952_poweroff *data = platform_get_drvdata(pdev); pm_power_off = NULL; hrtimer_cancel(&data->timer_trigger); hrtimer_cancel(&data->timer_wde); atomic_notifier_chain_unregister(&panic_notifier_list, &data->panic_notifier); return 0; } static const struct of_device_id of_ltc2952_poweroff_match[] = { { .compatible = "lltc,ltc2952"}, {}, }; MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match); static struct platform_driver ltc2952_poweroff_driver = { .probe = ltc2952_poweroff_probe, .remove = ltc2952_poweroff_remove, .driver = { .name = "ltc2952-poweroff", .of_match_table = of_ltc2952_poweroff_match, }, }; module_platform_driver(ltc2952_poweroff_driver); MODULE_AUTHOR("René Moll <rene.moll@xsens.com>"); MODULE_DESCRIPTION("LTC PowerPath power-off driver"); MODULE_LICENSE("GPL v2"); |