drivers/power/reset/ep93xx-restart.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Cirrus EP93xx SoC reset driver
   4  *
   5  * Copyright (C) 2021 Nikita Shubin <[email protected]>
   6  */
   7
   8 #include <linux/bits.h>
   9 #include <linux/container_of.h>
  10 #include <linux/delay.h>
  11 #include <linux/errno.h>
  12 #include <linux/mfd/syscon.h>
  13 #include <linux/module.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/notifier.h>
  16 #include <linux/reboot.h>
  17 #include <linux/slab.h>
  18
  19 #include <linux/soc/cirrus/ep93xx.h>
  20
  21 #define EP93XX_SYSCON_DEVCFG            0x80
  22 #define EP93XX_SYSCON_DEVCFG_SWRST      BIT(31)
  23
  24 struct ep93xx_restart {
  25         struct ep93xx_regmap_adev *aux_dev;
  26         struct notifier_block restart_handler;
  27 };
  28
  29 static int ep93xx_restart_handle(struct notifier_block *this,
  30                                  unsigned long mode, void *cmd)
  31 {
  32         struct ep93xx_restart *priv =
  33                 container_of(this, struct ep93xx_restart, restart_handler);
  34         struct ep93xx_regmap_adev *aux = priv->aux_dev;
  35
  36         /* Issue the reboot */
  37         aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG,
  38                          EP93XX_SYSCON_DEVCFG_SWRST, EP93XX_SYSCON_DEVCFG_SWRST);
  39         aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG,
  40                          EP93XX_SYSCON_DEVCFG_SWRST, 0);
  41
  42         return NOTIFY_DONE;
  43 }
  44
  45 static int ep93xx_reboot_probe(struct auxiliary_device *adev,
  46                                const struct auxiliary_device_id *id)
  47 {
  48         struct ep93xx_regmap_adev *rdev = to_ep93xx_regmap_adev(adev);
  49         struct device *dev = &adev->dev;
  50         struct ep93xx_restart *priv;
  51         int err;
  52
  53         if (!rdev->update_bits)
  54                 return -ENODEV;
  55
  56         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
  57         if (!priv)
  58                 return -ENOMEM;
  59
  60         priv->aux_dev = rdev;
  61
  62         priv->restart_handler.notifier_call = ep93xx_restart_handle;
  63         priv->restart_handler.priority = 128;
  64
  65         err = register_restart_handler(&priv->restart_handler);
  66         if (err)
  67                 return dev_err_probe(dev, err, "can't register restart notifier\n");
  68
  69         return 0;
  70 }
  71
  72 static const struct auxiliary_device_id ep93xx_reboot_ids[] = {
  73         {
  74                 .name = "soc_ep93xx.reset-ep93xx",
  75         },
  76         { /* sentinel */ }
  77 };
  78 MODULE_DEVICE_TABLE(auxiliary, ep93xx_reboot_ids);
  79
  80 static struct auxiliary_driver ep93xx_reboot_driver = {
  81         .probe          = ep93xx_reboot_probe,
  82         .id_table       = ep93xx_reboot_ids,
  83 };
  84 module_auxiliary_driver(ep93xx_reboot_driver);