1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Generic Syscon Reboot Driver
5 * Copyright (c) 2013, Applied Micro Circuits Corporation
6 * Author: Feng Kan <fkan@apm.com>
8 #include <linux/delay.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>
18 struct syscon_reboot_context {
23 struct notifier_block restart_handler;
26 static int syscon_restart_handle(struct notifier_block *this,
27 unsigned long mode, void *cmd)
29 struct syscon_reboot_context *ctx =
30 container_of(this, struct syscon_reboot_context,
33 /* Issue the reboot */
34 regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
38 pr_emerg("Unable to restart system\n");
42 static int syscon_reboot_probe(struct platform_device *pdev)
44 struct syscon_reboot_context *ctx;
45 struct device *dev = &pdev->dev;
46 int mask_err, value_err;
49 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
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);
57 return PTR_ERR(ctx->map);
60 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
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'");
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;
79 ctx->restart_handler.notifier_call = syscon_restart_handle;
80 ctx->restart_handler.priority = 192;
81 err = register_restart_handler(&ctx->restart_handler);
83 dev_err(dev, "can't register restart notifier (err=%d)\n", err);
88 static const struct of_device_id syscon_reboot_of_match[] = {
89 { .compatible = "syscon-reboot" },
93 static struct platform_driver syscon_reboot_driver = {
94 .probe = syscon_reboot_probe,
96 .name = "syscon-reboot",
97 .of_match_table = syscon_reboot_of_match,
100 builtin_platform_driver(syscon_reboot_driver);