1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Renesas R-Mobile Reset Driver
4  *
5  * Copyright (C) 2014 Glider bvba
6  */
7 
8 #include <linux/io.h>
9 #include <linux/module.h>
10 #include <linux/notifier.h>
11 #include <linux/of_address.h>
12 #include <linux/platform_device.h>
13 #include <linux/printk.h>
14 #include <linux/reboot.h>
15 
16 /* SYSC Register Bank 2 */
17 #define RESCNT2		0x20		/* Reset Control Register 2 */
18 
19 /* Reset Control Register 2 */
20 #define RESCNT2_PRES	0x80000000	/* Soft power-on reset */
21 
22 static void __iomem *sysc_base2;
23 
24 static int rmobile_reset_handler(struct notifier_block *this,
25 				 unsigned long mode, void *cmd)
26 {
27 	pr_debug("%s %lu\n", __func__, mode);
28 
29 	/* Let's assume we have acquired the HPB semaphore */
30 	writel(RESCNT2_PRES, sysc_base2 + RESCNT2);
31 
32 	return NOTIFY_DONE;
33 }
34 
35 static struct notifier_block rmobile_reset_nb = {
36 	.notifier_call = rmobile_reset_handler,
37 	.priority = 192,
38 };
39 
40 static int rmobile_reset_probe(struct platform_device *pdev)
41 {
42 	int error;
43 
44 	sysc_base2 = of_iomap(pdev->dev.of_node, 1);
45 	if (!sysc_base2)
46 		return -ENODEV;
47 
48 	error = register_restart_handler(&rmobile_reset_nb);
49 	if (error) {
50 		dev_err(&pdev->dev,
51 			"cannot register restart handler (err=%d)\n", error);
52 		goto fail_unmap;
53 	}
54 
55 	return 0;
56 
57 fail_unmap:
58 	iounmap(sysc_base2);
59 	return error;
60 }
61 
62 static int rmobile_reset_remove(struct platform_device *pdev)
63 {
64 	unregister_restart_handler(&rmobile_reset_nb);
65 	iounmap(sysc_base2);
66 	return 0;
67 }
68 
69 static const struct of_device_id rmobile_reset_of_match[] = {
70 	{ .compatible = "renesas,sysc-rmobile", },
71 	{ /* sentinel */ }
72 };
73 MODULE_DEVICE_TABLE(of, rmobile_reset_of_match);
74 
75 static struct platform_driver rmobile_reset_driver = {
76 	.probe = rmobile_reset_probe,
77 	.remove = rmobile_reset_remove,
78 	.driver = {
79 		.name = "rmobile_reset",
80 		.of_match_table = rmobile_reset_of_match,
81 	},
82 };
83 
84 module_platform_driver(rmobile_reset_driver);
85 
86 MODULE_DESCRIPTION("Renesas R-Mobile Reset Driver");
87 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
88 MODULE_LICENSE("GPL v2");
89