drivers/power/reset/syscon-poweroff.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Generic Syscon Poweroff Driver
   4  *
   5  * Copyright (c) 2015, National Instruments Corp.
   6  * Author: Moritz Fischer <moritz.fischer@ettus.com>
   7  */
   8
   9 #include <linux/delay.h>
  10 #include <linux/io.h>
  11 #include <linux/notifier.h>
  12 #include <linux/mfd/syscon.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/pm.h>
  16 #include <linux/reboot.h>
  17 #include <linux/regmap.h>
  18
  19 struct syscon_poweroff_data {
  20         struct regmap *map;
  21         u32 offset;
  22         u32 value;
  23         u32 mask;
  24 };
  25
  26 static int syscon_poweroff(struct sys_off_data *off_data)
  27 {
  28         struct syscon_poweroff_data *data = off_data->cb_data;
  29
  30         /* Issue the poweroff */
  31         regmap_update_bits(data->map, data->offset, data->mask, data->value);
  32
  33         mdelay(1000);
  34
  35         pr_emerg("Unable to poweroff system\n");
  36
  37         return NOTIFY_DONE;
  38 }
  39
  40 static int syscon_poweroff_probe(struct platform_device *pdev)
  41 {
  42         struct device *dev = &pdev->dev;
  43         struct syscon_poweroff_data *data;
  44         int mask_err, value_err;
  45
  46         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  47         if (!data)
  48                 return -ENOMEM;
  49
  50         data->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
  51         if (IS_ERR(data->map)) {
  52                 data->map = syscon_node_to_regmap(dev->parent->of_node);
  53                 if (IS_ERR(data->map)) {
  54                         dev_err(dev, "unable to get syscon");
  55                         return PTR_ERR(data->map);
  56                 }
  57         }
  58
  59         if (of_property_read_u32(dev->of_node, "offset", &data->offset)) {
  60                 dev_err(dev, "unable to read 'offset'");
  61                 return -EINVAL;
  62         }
  63
  64         value_err = of_property_read_u32(dev->of_node, "value", &data->value);
  65         mask_err = of_property_read_u32(dev->of_node, "mask", &data->mask);
  66         if (value_err && mask_err) {
  67                 dev_err(dev, "unable to read 'value' and 'mask'");
  68                 return -EINVAL;
  69         }
  70
  71         if (value_err) {
  72                 /* support old binding */
  73                 data->value = data->mask;
  74                 data->mask = 0xFFFFFFFF;
  75         } else if (mask_err) {
  76                 /* support value without mask*/
  77                 data->mask = 0xFFFFFFFF;
  78         }
  79
  80         return devm_register_sys_off_handler(&pdev->dev,
  81                                              SYS_OFF_MODE_POWER_OFF,
  82                                              SYS_OFF_PRIO_DEFAULT,
  83                                              syscon_poweroff, data);
  84 }
  85
  86 static const struct of_device_id syscon_poweroff_of_match[] = {
  87         { .compatible = "syscon-poweroff" },
  88         {}
  89 };
  90
  91 static struct platform_driver syscon_poweroff_driver = {
  92         .probe = syscon_poweroff_probe,
  93         .driver = {
  94                 .name = "syscon-poweroff",
  95                 .of_match_table = syscon_poweroff_of_match,
  96         },
  97 };
  98 builtin_platform_driver(syscon_poweroff_driver);