1/*
2 * TI keystone reboot driver
3 *
4 * Copyright (C) 2014 Texas Instruments Incorporated. http://www.ti.com/
5 *
6 * Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/io.h>
14#include <linux/module.h>
15#include <linux/notifier.h>
16#include <linux/reboot.h>
17#include <linux/regmap.h>
18#include <linux/mfd/syscon.h>
19#include <linux/of_platform.h>
20
21#define RSTYPE_RG			0x0
22#define RSCTRL_RG			0x4
23#define RSCFG_RG			0x8
24#define RSISO_RG			0xc
25
26#define RSCTRL_KEY_MASK			0x0000ffff
27#define RSCTRL_RESET_MASK		BIT(16)
28#define RSCTRL_KEY			0x5a69
29
30#define RSMUX_OMODE_MASK		0xe
31#define RSMUX_OMODE_RESET_ON		0xa
32#define RSMUX_OMODE_RESET_OFF		0x0
33#define RSMUX_LOCK_MASK			0x1
34#define RSMUX_LOCK_SET			0x1
35
36#define RSCFG_RSTYPE_SOFT		0x300f
37#define RSCFG_RSTYPE_HARD		0x0
38
39#define WDT_MUX_NUMBER			0x4
40
41static int rspll_offset;
42static struct regmap *pllctrl_regs;
43
44/**
45 * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
46 * To be able to access to RSCTRL, RSCFG registers
47 * we have to write a key before
48 */
49static inline int rsctrl_enable_rspll_write(void)
50{
51	return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
52				  RSCTRL_KEY_MASK, RSCTRL_KEY);
53}
54
55static int rsctrl_restart_handler(struct notifier_block *this,
56				  unsigned long mode, void *cmd)
57{
58	/* enable write access to RSTCTRL */
59	rsctrl_enable_rspll_write();
60
61	/* reset the SOC */
62	regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
63			   RSCTRL_RESET_MASK, 0);
64
65	return NOTIFY_DONE;
66}
67
68static struct notifier_block rsctrl_restart_nb = {
69	.notifier_call = rsctrl_restart_handler,
70	.priority = 128,
71};
72
73static const struct of_device_id rsctrl_of_match[] = {
74	{.compatible = "ti,keystone-reset", },
75	{},
76};
77
78static int rsctrl_probe(struct platform_device *pdev)
79{
80	int i;
81	int ret;
82	u32 val;
83	unsigned int rg;
84	u32 rsmux_offset;
85	struct regmap *devctrl_regs;
86	struct device *dev = &pdev->dev;
87	struct device_node *np = dev->of_node;
88
89	if (!np)
90		return -ENODEV;
91
92	/* get regmaps */
93	pllctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-pll");
94	if (IS_ERR(pllctrl_regs))
95		return PTR_ERR(pllctrl_regs);
96
97	devctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-dev");
98	if (IS_ERR(devctrl_regs))
99		return PTR_ERR(devctrl_regs);
100
101	ret = of_property_read_u32_index(np, "ti,syscon-pll", 1, &rspll_offset);
102	if (ret) {
103		dev_err(dev, "couldn't read the reset pll offset!\n");
104		return -EINVAL;
105	}
106
107	ret = of_property_read_u32_index(np, "ti,syscon-dev", 1, &rsmux_offset);
108	if (ret) {
109		dev_err(dev, "couldn't read the rsmux offset!\n");
110		return -EINVAL;
111	}
112
113	/* set soft/hard reset */
114	val = of_property_read_bool(np, "ti,soft-reset");
115	val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
116
117	ret = rsctrl_enable_rspll_write();
118	if (ret)
119		return ret;
120
121	ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
122	if (ret)
123		return ret;
124
125	/* disable a reset isolation for all module clocks */
126	ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
127	if (ret)
128		return ret;
129
130	/* enable a reset for watchdogs from wdt-list */
131	for (i = 0; i < WDT_MUX_NUMBER; i++) {
132		ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
133		if (ret == -EOVERFLOW && !i) {
134			dev_err(dev, "ti,wdt-list property has to contain at"
135				"least one entry\n");
136			return -EINVAL;
137		} else if (ret) {
138			break;
139		}
140
141		if (val >= WDT_MUX_NUMBER) {
142			dev_err(dev, "ti,wdt-list property can contain"
143				"only numbers < 4\n");
144			return -EINVAL;
145		}
146
147		rg = rsmux_offset + val * 4;
148
149		ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
150					 RSMUX_OMODE_RESET_ON |
151					 RSMUX_LOCK_SET);
152		if (ret)
153			return ret;
154	}
155
156	ret = register_restart_handler(&rsctrl_restart_nb);
157	if (ret)
158		dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
159
160	return ret;
161}
162
163static struct platform_driver rsctrl_driver = {
164	.probe = rsctrl_probe,
165	.driver = {
166		.name = KBUILD_MODNAME,
167		.of_match_table = rsctrl_of_match,
168	},
169};
170module_platform_driver(rsctrl_driver);
171
172MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
173MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
174MODULE_LICENSE("GPL v2");
175MODULE_ALIAS("platform:" KBUILD_MODNAME);
176