LXR linux/drivers/power/reset/syscon-reboot.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Generic Syscon Reboot Driver
   4 *
   5 * Copyright (c) 2013, Applied Micro Circuits Corporation
   6 * Author: Feng Kan <fkan@apm.com>
   7 */
   8#include <linux/delay.h>
   9#include <linux/io.h>
  10#include <linux/notifier.h>
  11#include <linux/mfd/syscon.h>
  12#include <linux/of_address.h>
  13#include <linux/of_device.h>
  14#include <linux/platform_device.h>
  15#include <linux/reboot.h>
  16#include <linux/regmap.h>
  17
  18struct syscon_reboot_context {
  19        struct regmap *map;
  20        u32 offset;
  21        u32 value;
  22        u32 mask;
  23        struct notifier_block restart_handler;
  24};
  25
  26static int syscon_restart_handle(struct notifier_block *this,
  27                                        unsigned long mode, void *cmd)
  28{
  29        struct syscon_reboot_context *ctx =
  30                        container_of(this, struct syscon_reboot_context,
  31                                        restart_handler);
  32
  33        /* Issue the reboot */
  34        regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
  35
  36        mdelay(1000);
  37
  38        pr_emerg("Unable to restart system\n");
  39        return NOTIFY_DONE;
  40}
  41
  42static int syscon_reboot_probe(struct platform_device *pdev)
  43{
  44        struct syscon_reboot_context *ctx;
  45        struct device *dev = &pdev->dev;
  46        int mask_err, value_err;
  47        int err;
  48
  49        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
  50        if (!ctx)
  51                return -ENOMEM;
  52
  53        ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
  54        if (IS_ERR(ctx->map)) {
  55                ctx->map = syscon_node_to_regmap(dev->parent->of_node);
  56                if (IS_ERR(ctx->map))
  57                        return PTR_ERR(ctx->map);
  58        }
  59
  60        if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
  61                return -EINVAL;
  62
  63        value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
  64        mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
  65        if (value_err && mask_err) {
  66                dev_err(dev, "unable to read 'value' and 'mask'");
  67                return -EINVAL;
  68        }
  69
  70        if (value_err) {
  71                /* support old binding */
  72                ctx->value = ctx->mask;
  73                ctx->mask = 0xFFFFFFFF;
  74        } else if (mask_err) {
  75                /* support value without mask*/
  76                ctx->mask = 0xFFFFFFFF;
  77        }
  78
  79        ctx->restart_handler.notifier_call = syscon_restart_handle;
  80        ctx->restart_handler.priority = 192;
  81        err = register_restart_handler(&ctx->restart_handler);
  82        if (err)
  83                dev_err(dev, "can't register restart notifier (err=%d)\n", err);
  84
  85        return err;
  86}
  87
  88static const struct of_device_id syscon_reboot_of_match[] = {
  89        { .compatible = "syscon-reboot" },
  90        {}
  91};
  92
  93static struct platform_driver syscon_reboot_driver = {
  94        .probe = syscon_reboot_probe,
  95        .driver = {
  96                .name = "syscon-reboot",
  97                .of_match_table = syscon_reboot_of_match,
  98        },
  99};
 100builtin_platform_driver(syscon_reboot_driver);
 101