1 /*
2  * Copyright (C) 2016 Broadcom
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation version 2.
7  *
8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9  * kind, whether express or implied; without even the implied warranty
10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  */
13 
14 #include <linux/io.h>
15 #include <linux/of_address.h>
16 #include <linux/of_platform.h>
17 #include <linux/reboot.h>
18 
19 #define RSTMGR_REG_WR_ACCESS_OFFSET	0
20 #define RSTMGR_REG_CHIP_SOFT_RST_OFFSET	4
21 
22 #define RSTMGR_WR_PASSWORD		0xa5a5
23 #define RSTMGR_WR_PASSWORD_SHIFT	8
24 #define RSTMGR_WR_ACCESS_ENABLE		1
25 
26 static void __iomem *kona_reset_base;
27 
kona_reset_handler(struct notifier_block * this,unsigned long mode,void * cmd)28 static int kona_reset_handler(struct notifier_block *this,
29 				unsigned long mode, void *cmd)
30 {
31 	/*
32 	 * A soft reset is triggered by writing a 0 to bit 0 of the soft reset
33 	 * register. To write to that register we must first write the password
34 	 * and the enable bit in the write access enable register.
35 	 */
36 	writel((RSTMGR_WR_PASSWORD << RSTMGR_WR_PASSWORD_SHIFT) |
37 		RSTMGR_WR_ACCESS_ENABLE,
38 		kona_reset_base + RSTMGR_REG_WR_ACCESS_OFFSET);
39 	writel(0, kona_reset_base + RSTMGR_REG_CHIP_SOFT_RST_OFFSET);
40 
41 	return NOTIFY_DONE;
42 }
43 
44 static struct notifier_block kona_reset_nb = {
45 	.notifier_call = kona_reset_handler,
46 	.priority = 128,
47 };
48 
kona_reset_probe(struct platform_device * pdev)49 static int kona_reset_probe(struct platform_device *pdev)
50 {
51 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
52 
53 	kona_reset_base = devm_ioremap_resource(&pdev->dev, res);
54 	if (IS_ERR(kona_reset_base))
55 		return PTR_ERR(kona_reset_base);
56 
57 	return register_restart_handler(&kona_reset_nb);
58 }
59 
60 static const struct of_device_id of_match[] = {
61 	{ .compatible = "brcm,bcm21664-resetmgr" },
62 	{},
63 };
64 
65 static struct platform_driver bcm_kona_reset_driver = {
66 	.probe = kona_reset_probe,
67 	.driver = {
68 		.name = "brcm-kona-reset",
69 		.of_match_table = of_match,
70 	},
71 };
72 
73 builtin_platform_driver(bcm_kona_reset_driver);
74