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
26static void __iomem *kona_reset_base;
27
28static 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
44static struct notifier_block kona_reset_nb = {
45	.notifier_call = kona_reset_handler,
46	.priority = 128,
47};
48
49static 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
60static const struct of_device_id of_match[] = {
61	{ .compatible = "brcm,bcm21664-resetmgr" },
62	{},
63};
64
65static 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
73builtin_platform_driver(bcm_kona_reset_driver);