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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Generic Syscon Reboot Driver4 *5 * Copyright (c) 2013, Applied Micro Circuits Corporation6 * 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 return -EINVAL;65 66 value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);67 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);68 if (value_err && mask_err) {69 dev_err(dev, "unable to read 'value' and 'mask'");70 return -EINVAL;71 }72 73 if (value_err) {74 /* support old binding */75 ctx->value = ctx->mask;76 ctx->mask = 0xFFFFFFFF;77 } else if (mask_err) {78 /* support value without mask*/79 ctx->mask = 0xFFFFFFFF;80 }81 82 ctx->restart_handler.notifier_call = syscon_restart_handle;83 ctx->restart_handler.priority = priority;84 err = register_restart_handler(&ctx->restart_handler);85 if (err)86 dev_err(dev, "can't register restart notifier (err=%d)\n", err);87 88 return err;89}90 91static const struct of_device_id syscon_reboot_of_match[] = {92 { .compatible = "syscon-reboot" },93 {}94};95 96static struct platform_driver syscon_reboot_driver = {97 .probe = syscon_reboot_probe,98 .driver = {99 .name = "syscon-reboot",100 .of_match_table = syscon_reboot_of_match,101 },102};103builtin_platform_driver(syscon_reboot_driver);104