1 /*
2  * Renesas R-Mobile Reset Driver
3  *
4  * Copyright (C) 2014 Glider bvba
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License.  See the file "COPYING" in the main directory of this archive
8  * for more details.
9  */
10 
11 #include <linux/io.h>
12 #include <linux/module.h>
13 #include <linux/notifier.h>
14 #include <linux/of_address.h>
15 #include <linux/platform_device.h>
16 #include <linux/printk.h>
17 #include <linux/reboot.h>
18 
19 /* SYSC Register Bank 2 */
20 #define RESCNT2		0x20		/* Reset Control Register 2 */
21 
22 /* Reset Control Register 2 */
23 #define RESCNT2_PRES	0x80000000	/* Soft power-on reset */
24 
25 static void __iomem *sysc_base2;
26 
27 static int rmobile_reset_handler(struct notifier_block *this,
28 				 unsigned long mode, void *cmd)
29 {
30 	pr_debug("%s %lu\n", __func__, mode);
31 
32 	/* Let's assume we have acquired the HPB semaphore */
33 	writel(RESCNT2_PRES, sysc_base2 + RESCNT2);
34 
35 	return NOTIFY_DONE;
36 }
37 
38 static struct notifier_block rmobile_reset_nb = {
39 	.notifier_call = rmobile_reset_handler,
40 	.priority = 192,
41 };
42 
43 static int rmobile_reset_probe(struct platform_device *pdev)
44 {
45 	int error;
46 
47 	sysc_base2 = of_iomap(pdev->dev.of_node, 1);
48 	if (!sysc_base2)
49 		return -ENODEV;
50 
51 	error = register_restart_handler(&rmobile_reset_nb);
52 	if (error) {
53 		dev_err(&pdev->dev,
54 			"cannot register restart handler (err=%d)\n", error);
55 		goto fail_unmap;
56 	}
57 
58 	return 0;
59 
60 fail_unmap:
61 	iounmap(sysc_base2);
62 	return error;
63 }
64 
65 static int rmobile_reset_remove(struct platform_device *pdev)
66 {
67 	unregister_restart_handler(&rmobile_reset_nb);
68 	iounmap(sysc_base2);
69 	return 0;
70 }
71 
72 static const struct of_device_id rmobile_reset_of_match[] = {
73 	{ .compatible = "renesas,sysc-rmobile", },
74 	{ /* sentinel */ }
75 };
76 MODULE_DEVICE_TABLE(of, rmobile_reset_of_match);
77 
78 static struct platform_driver rmobile_reset_driver = {
79 	.probe = rmobile_reset_probe,
80 	.remove = rmobile_reset_remove,
81 	.driver = {
82 		.name = "rmobile_reset",
83 		.of_match_table = rmobile_reset_of_match,
84 	},
85 };
86 
87 module_platform_driver(rmobile_reset_driver);
88 
89 MODULE_DESCRIPTION("Renesas R-Mobile Reset Driver");
90 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
91 MODULE_LICENSE("GPL v2");
92