root/drivers/power/reset/ltc2952-poweroff.c

DEFINITIONS

1. ltc2952_poweroff_timer_wde
2. ltc2952_poweroff_start_wde
3. ltc2952_poweroff_timer_trigger
4. ltc2952_poweroff_handler
5. ltc2952_poweroff_kill
6. ltc2952_poweroff_default
7. ltc2952_poweroff_init
8. ltc2952_poweroff_notify_panic
9. ltc2952_poweroff_probe
10. ltc2952_poweroff_remove

   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");