drivers/power/reset/syscon-reboot.c

   1 /*
   2  * Generic Syscon Reboot Driver
   3  *
   4  * Copyright (c) 2013, Applied Micro Circuits Corporation
   5  * Author: Feng Kan <fkan@apm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of
  10  * the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17 #include <linux/delay.h>
  18 #include <linux/io.h>
  19 #include <linux/notifier.h>
  20 #include <linux/mfd/syscon.h>
  21 #include <linux/of_address.h>
  22 #include <linux/of_device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/reboot.h>
  25 #include <linux/regmap.h>
  26
  27 struct syscon_reboot_context {
  28         struct regmap *map;
  29         u32 offset;
  30         u32 mask;
  31         struct notifier_block restart_handler;
  32 };
  33
  34 static int syscon_restart_handle(struct notifier_block *this,
  35                                         unsigned long mode, void *cmd)
  36 {
  37         struct syscon_reboot_context *ctx =
  38                         container_of(this, struct syscon_reboot_context,
  39                                         restart_handler);
  40
  41         /* Issue the reboot */
  42         regmap_write(ctx->map, ctx->offset, ctx->mask);
  43
  44         mdelay(1000);
  45
  46         pr_emerg("Unable to restart system\n");
  47         return NOTIFY_DONE;
  48 }
  49
  50 static int syscon_reboot_probe(struct platform_device *pdev)
  51 {
  52         struct syscon_reboot_context *ctx;
  53         struct device *dev = &pdev->dev;
  54         int err;
  55
  56         ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
  57         if (!ctx)
  58                 return -ENOMEM;
  59
  60         ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
  61         if (IS_ERR(ctx->map))
  62                 return PTR_ERR(ctx->map);
  63
  64         if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
  65                 return -EINVAL;
  66
  67         if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask))
  68                 return -EINVAL;
  69
  70         ctx->restart_handler.notifier_call = syscon_restart_handle;
  71         ctx->restart_handler.priority = 192;
  72         err = register_restart_handler(&ctx->restart_handler);
  73         if (err)
  74                 dev_err(dev, "can't register restart notifier (err=%d)\n", err);
  75
  76         return err;
  77 }
  78
  79 static const struct of_device_id syscon_reboot_of_match[] = {
  80         { .compatible = "syscon-reboot" },
  81         {}
  82 };
  83
  84 static struct platform_driver syscon_reboot_driver = {
  85         .probe = syscon_reboot_probe,
  86         .driver = {
  87                 .name = "syscon-reboot",
  88                 .of_match_table = syscon_reboot_of_match,
  89         },
  90 };
  91 builtin_platform_driver(syscon_reboot_driver);