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 value;
  32 static u32 mask;
  33
  34 static void syscon_poweroff(void)
  35 {
  36         /* Issue the poweroff */
  37         regmap_update_bits(map, offset, mask, value);
  38
  39         mdelay(1000);
  40
  41         pr_emerg("Unable to poweroff system\n");
  42 }
  43
  44 static int syscon_poweroff_probe(struct platform_device *pdev)
  45 {
  46         char symname[KSYM_NAME_LEN];
  47         int mask_err, value_err;
  48
  49         map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
  50         if (IS_ERR(map)) {
  51                 dev_err(&pdev->dev, "unable to get syscon");
  52                 return PTR_ERR(map);
  53         }
  54
  55         if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
  56                 dev_err(&pdev->dev, "unable to read 'offset'");
  57                 return -EINVAL;
  58         }
  59
  60         value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
  61         mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
  62         if (value_err && mask_err) {
  63                 dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
  64                 return -EINVAL;
  65         }
  66
  67         if (value_err) {
  68                 /* support old binding */
  69                 value = mask;
  70                 mask = 0xFFFFFFFF;
  71         } else if (mask_err) {
  72                 /* support value without mask*/
  73                 mask = 0xFFFFFFFF;
  74         }
  75
  76         if (pm_power_off) {
  77                 lookup_symbol_name((ulong)pm_power_off, symname);
  78                 dev_err(&pdev->dev,
  79                 "pm_power_off already claimed %p %s",
  80                 pm_power_off, symname);
  81                 return -EBUSY;
  82         }
  83
  84         pm_power_off = syscon_poweroff;
  85
  86         return 0;
  87 }
  88
  89 static int syscon_poweroff_remove(struct platform_device *pdev)
  90 {
  91         if (pm_power_off == syscon_poweroff)
  92                 pm_power_off = NULL;
  93
  94         return 0;
  95 }
  96
  97 static const struct of_device_id syscon_poweroff_of_match[] = {
  98         { .compatible = "syscon-poweroff" },
  99         {}
 100 };
 101
 102 static struct platform_driver syscon_poweroff_driver = {
 103         .probe = syscon_poweroff_probe,
 104         .remove = syscon_poweroff_remove,
 105         .driver = {
 106                 .name = "syscon-poweroff",
 107                 .of_match_table = syscon_poweroff_of_match,
 108         },
 109 };
 110
 111 static int __init syscon_poweroff_register(void)
 112 {
 113         return platform_driver_register(&syscon_poweroff_driver);
 114 }
 115 device_initcall(syscon_poweroff_register);