drivers/power/reset/syscon-poweroff.c

   1 /*
   2  * Generic Syscon Poweroff Driver
   3  *
   4  * Copyright (c) 2015, National Instruments Corp.
   5  * Author: Moritz Fischer <moritz.fischer@ettus.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
  18 #include <linux/kallsyms.h>
  19 #include <linux/delay.h>
  20 #include <linux/io.h>
  21 #include <linux/notifier.h>
  22 #include <linux/mfd/syscon.h>
  23 #include <linux/of_address.h>
  24 #include <linux/of_device.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/pm.h>
  27 #include <linux/regmap.h>
  28
  29 static struct regmap *map;
  30 static u32 offset;
  31 static u32 mask;
  32
  33 void syscon_poweroff(void)
  34 {
  35         /* Issue the poweroff */
  36         regmap_write(map, offset, mask);
  37
  38         mdelay(1000);
  39
  40         pr_emerg("Unable to poweroff system\n");
  41 }
  42
  43 static int syscon_poweroff_probe(struct platform_device *pdev)
  44 {
  45         char symname[KSYM_NAME_LEN];
  46
  47         map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
  48         if (IS_ERR(map)) {
  49                 dev_err(&pdev->dev, "unable to get syscon");
  50                 return PTR_ERR(map);
  51         }
  52
  53         if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
  54                 dev_err(&pdev->dev, "unable to read 'offset'");
  55                 return -EINVAL;
  56         }
  57
  58         if (of_property_read_u32(pdev->dev.of_node, "mask", &mask)) {
  59                 dev_err(&pdev->dev, "unable to read 'mask'");
  60                 return -EINVAL;
  61         }
  62
  63         if (pm_power_off) {
  64                 lookup_symbol_name((ulong)pm_power_off, symname);
  65                 dev_err(&pdev->dev,
  66                 "pm_power_off already claimed %p %s",
  67                 pm_power_off, symname);
  68                 return -EBUSY;
  69         }
  70
  71         pm_power_off = syscon_poweroff;
  72
  73         return 0;
  74 }
  75
  76 static int syscon_poweroff_remove(struct platform_device *pdev)
  77 {
  78         if (pm_power_off == syscon_poweroff)
  79                 pm_power_off = NULL;
  80
  81         return 0;
  82 }
  83
  84 static const struct of_device_id syscon_poweroff_of_match[] = {
  85         { .compatible = "syscon-poweroff" },
  86         {}
  87 };
  88
  89 static struct platform_driver syscon_poweroff_driver = {
  90         .probe = syscon_poweroff_probe,
  91         .remove = syscon_poweroff_remove,
  92         .driver = {
  93                 .name = "syscon-poweroff",
  94                 .of_match_table = syscon_poweroff_of_match,
  95         },
  96 };
  97
  98 static int __init syscon_poweroff_register(void)
  99 {
 100         return platform_driver_register(&syscon_poweroff_driver);
 101 }
 102 device_initcall(syscon_poweroff_register);