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
18 struct syscon_reboot_context {
19 struct regmap *map;
20 u32 offset;
21 u32 value;
22 u32 mask;
23 struct notifier_block restart_handler;
24 };
25
syscon_restart_handle(struct notifier_block * this,unsigned long mode,void * cmd)26 static 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
syscon_reboot_probe(struct platform_device * pdev)42 static 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 return PTR_ERR(ctx->map);
56
57 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
58 return -EINVAL;
59
60 value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
61 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
62 if (value_err && mask_err) {
63 dev_err(dev, "unable to read 'value' and 'mask'");
64 return -EINVAL;
65 }
66
67 if (value_err) {
68 /* support old binding */
69 ctx->value = ctx->mask;
70 ctx->mask = 0xFFFFFFFF;
71 } else if (mask_err) {
72 /* support value without mask*/
73 ctx->mask = 0xFFFFFFFF;
74 }
75
76 ctx->restart_handler.notifier_call = syscon_restart_handle;
77 ctx->restart_handler.priority = 192;
78 err = register_restart_handler(&ctx->restart_handler);
79 if (err)
80 dev_err(dev, "can't register restart notifier (err=%d)\n", err);
81
82 return err;
83 }
84
85 static const struct of_device_id syscon_reboot_of_match[] = {
86 { .compatible = "syscon-reboot" },
87 {}
88 };
89
90 static struct platform_driver syscon_reboot_driver = {
91 .probe = syscon_reboot_probe,
92 .driver = {
93 .name = "syscon-reboot",
94 .of_match_table = syscon_reboot_of_match,
95 },
96 };
97 builtin_platform_driver(syscon_reboot_driver);
98
