drivers/power/reset/vexpress-poweroff.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (C) 2012 ARM Limited
   5  */
   6
   7 #include <linux/delay.h>
   8 #include <linux/notifier.h>
   9 #include <linux/of.h>
  10 #include <linux/of_device.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/reboot.h>
  13 #include <linux/stat.h>
  14 #include <linux/vexpress.h>
  15
  16 static void vexpress_reset_do(struct device *dev, const char *what)
  17 {
  18         int err = -ENOENT;
  19         struct regmap *reg = dev_get_drvdata(dev);
  20
  21         if (reg) {
  22                 err = regmap_write(reg, 0, 0);
  23                 if (!err)
  24                         mdelay(1000);
  25         }
  26
  27         dev_emerg(dev, "Unable to %s (%d)\n", what, err);
  28 }
  29
  30 static struct device *vexpress_power_off_device;
  31 static atomic_t vexpress_restart_nb_refcnt = ATOMIC_INIT(0);
  32
  33 static void vexpress_power_off(void)
  34 {
  35         vexpress_reset_do(vexpress_power_off_device, "power off");
  36 }
  37
  38 static struct device *vexpress_restart_device;
  39
  40 static int vexpress_restart(struct notifier_block *this, unsigned long mode,
  41                              void *cmd)
  42 {
  43         vexpress_reset_do(vexpress_restart_device, "restart");
  44
  45         return NOTIFY_DONE;
  46 }
  47
  48 static struct notifier_block vexpress_restart_nb = {
  49         .notifier_call = vexpress_restart,
  50         .priority = 128,
  51 };
  52
  53 static ssize_t vexpress_reset_active_show(struct device *dev,
  54                 struct device_attribute *attr, char *buf)
  55 {
  56         return sprintf(buf, "%d\n", vexpress_restart_device == dev);
  57 }
  58
  59 static ssize_t vexpress_reset_active_store(struct device *dev,
  60                 struct device_attribute *attr, const char *buf, size_t count)
  61 {
  62         long value;
  63         int err = kstrtol(buf, 0, &value);
  64
  65         if (!err && value)
  66                 vexpress_restart_device = dev;
  67
  68         return err ? err : count;
  69 }
  70
  71 static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
  72                    vexpress_reset_active_store);
  73
  74
  75 enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
  76
  77 static const struct of_device_id vexpress_reset_of_match[] = {
  78         {
  79                 .compatible = "arm,vexpress-reset",
  80                 .data = (void *)FUNC_RESET,
  81         }, {
  82                 .compatible = "arm,vexpress-shutdown",
  83                 .data = (void *)FUNC_SHUTDOWN
  84         }, {
  85                 .compatible = "arm,vexpress-reboot",
  86                 .data = (void *)FUNC_REBOOT
  87         },
  88         {}
  89 };
  90
  91 static int _vexpress_register_restart_handler(struct device *dev)
  92 {
  93         int err;
  94
  95         vexpress_restart_device = dev;
  96         if (atomic_inc_return(&vexpress_restart_nb_refcnt) == 1) {
  97                 err = register_restart_handler(&vexpress_restart_nb);
  98                 if (err) {
  99                         dev_err(dev, "cannot register restart handler (err=%d)\n", err);
 100                         atomic_dec(&vexpress_restart_nb_refcnt);
 101                         return err;
 102                 }
 103         }
 104         device_create_file(dev, &dev_attr_active);
 105
 106         return 0;
 107 }
 108
 109 static int vexpress_reset_probe(struct platform_device *pdev)
 110 {
 111         const struct of_device_id *match =
 112                         of_match_device(vexpress_reset_of_match, &pdev->dev);
 113         struct regmap *regmap;
 114         int ret = 0;
 115
 116         if (!match)
 117                 return -EINVAL;
 118
 119         regmap = devm_regmap_init_vexpress_config(&pdev->dev);
 120         if (IS_ERR(regmap))
 121                 return PTR_ERR(regmap);
 122         dev_set_drvdata(&pdev->dev, regmap);
 123
 124         switch ((uintptr_t)match->data) {
 125         case FUNC_SHUTDOWN:
 126                 vexpress_power_off_device = &pdev->dev;
 127                 pm_power_off = vexpress_power_off;
 128                 break;
 129         case FUNC_RESET:
 130                 if (!vexpress_restart_device)
 131                         ret = _vexpress_register_restart_handler(&pdev->dev);
 132                 break;
 133         case FUNC_REBOOT:
 134                 ret = _vexpress_register_restart_handler(&pdev->dev);
 135                 break;
 136         }
 137
 138         return ret;
 139 }
 140
 141 static struct platform_driver vexpress_reset_driver = {
 142         .probe = vexpress_reset_probe,
 143         .driver = {
 144                 .name = "vexpress-reset",
 145                 .of_match_table = vexpress_reset_of_match,
 146                 .suppress_bind_attrs = true,
 147         },
 148 };
 149 builtin_platform_driver(vexpress_reset_driver);