drivers/power/reset/ltc2952-poweroff.c

   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");