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.h>
 13#include <linux/platform_device.h>
 14#include <linux/reboot.h>
 15#include <linux/regmap.h>
 16
 17struct syscon_reboot_context {
 18	struct regmap *map;
 19	u32 offset;
 20	u32 value;
 21	u32 mask;
 22	struct notifier_block restart_handler;
 23};
 24
 25static int syscon_restart_handle(struct notifier_block *this,
 26					unsigned long mode, void *cmd)
 27{
 28	struct syscon_reboot_context *ctx =
 29			container_of(this, struct syscon_reboot_context,
 30					restart_handler);
 31
 32	/* Issue the reboot */
 33	regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
 34
 35	mdelay(1000);
 36
 37	pr_emerg("Unable to restart system\n");
 38	return NOTIFY_DONE;
 39}
 40
 41static int syscon_reboot_probe(struct platform_device *pdev)
 42{
 43	struct syscon_reboot_context *ctx;
 44	struct device *dev = &pdev->dev;
 45	int mask_err, value_err;
 46	int priority;
 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_s32(pdev->dev.of_node, "priority", &priority))
 61		priority = 192;
 62
 63	if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
 64		if (of_property_read_u32(pdev->dev.of_node, "reg", &ctx->offset))
 65			return -EINVAL;
 66
 67	value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
 68	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
 69	if (value_err && mask_err) {
 70		dev_err(dev, "unable to read 'value' and 'mask'");
 71		return -EINVAL;
 72	}
 73
 74	if (value_err) {
 75		/* support old binding */
 76		ctx->value = ctx->mask;
 77		ctx->mask = 0xFFFFFFFF;
 78	} else if (mask_err) {
 79		/* support value without mask*/
 80		ctx->mask = 0xFFFFFFFF;
 81	}
 82
 83	ctx->restart_handler.notifier_call = syscon_restart_handle;
 84	ctx->restart_handler.priority = priority;
 85	err = register_restart_handler(&ctx->restart_handler);
 86	if (err)
 87		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
 88
 89	return err;
 90}
 91
 92static const struct of_device_id syscon_reboot_of_match[] = {
 93	{ .compatible = "syscon-reboot" },
 94	{}
 95};
 96
 97static struct platform_driver syscon_reboot_driver = {
 98	.probe = syscon_reboot_probe,
 99	.driver = {
100		.name = "syscon-reboot",
101		.of_match_table = syscon_reboot_of_match,
102	},
103};
104builtin_platform_driver(syscon_reboot_driver);