1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * HiSilicon SoC reset code
4  *
5  * Copyright (c) 2014 HiSilicon Ltd.
6  * Copyright (c) 2014 Linaro Ltd.
7  *
8  * Author: Haojian Zhuang <haojian.zhuang@linaro.org>
9  */
10 
11 #include <linux/delay.h>
12 #include <linux/io.h>
13 #include <linux/module.h>
14 #include <linux/notifier.h>
15 #include <linux/of_address.h>
16 #include <linux/platform_device.h>
17 #include <linux/reboot.h>
18 
19 #include <asm/proc-fns.h>
20 
21 static void __iomem *base;
22 static u32 reboot_offset;
23 
24 static int hisi_restart_handler(struct notifier_block *this,
25 				unsigned long mode, void *cmd)
26 {
27 	writel_relaxed(0xdeadbeef, base + reboot_offset);
28 
29 	while (1)
30 		cpu_do_idle();
31 
32 	return NOTIFY_DONE;
33 }
34 
35 static struct notifier_block hisi_restart_nb = {
36 	.notifier_call = hisi_restart_handler,
37 	.priority = 128,
38 };
39 
40 static int hisi_reboot_probe(struct platform_device *pdev)
41 {
42 	struct device_node *np = pdev->dev.of_node;
43 	int err;
44 
45 	base = of_iomap(np, 0);
46 	if (!base) {
47 		WARN(1, "failed to map base address");
48 		return -ENODEV;
49 	}
50 
51 	if (of_property_read_u32(np, "reboot-offset", &reboot_offset) < 0) {
52 		pr_err("failed to find reboot-offset property\n");
53 		iounmap(base);
54 		return -EINVAL;
55 	}
56 
57 	err = register_restart_handler(&hisi_restart_nb);
58 	if (err) {
59 		dev_err(&pdev->dev, "cannot register restart handler (err=%d)\n",
60 			err);
61 		iounmap(base);
62 	}
63 
64 	return err;
65 }
66 
67 static const struct of_device_id hisi_reboot_of_match[] = {
68 	{ .compatible = "hisilicon,sysctrl" },
69 	{}
70 };
71 MODULE_DEVICE_TABLE(of, hisi_reboot_of_match);
72 
73 static struct platform_driver hisi_reboot_driver = {
74 	.probe = hisi_reboot_probe,
75 	.driver = {
76 		.name = "hisi-reboot",
77 		.of_match_table = hisi_reboot_of_match,
78 	},
79 };
80 module_platform_driver(hisi_reboot_driver);
81