1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * TI keystone reboot driver
4 *
5 * Copyright (C) 2014 Texas Instruments Incorporated. https://www.ti.com/
6 *
7 * Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
8 */
9
10#include <linux/io.h>
11#include <linux/module.h>
12#include <linux/notifier.h>
13#include <linux/platform_device.h>
14#include <linux/reboot.h>
15#include <linux/regmap.h>
16#include <linux/mfd/syscon.h>
17#include <linux/of.h>
18
19#define RSTYPE_RG			0x0
20#define RSCTRL_RG			0x4
21#define RSCFG_RG			0x8
22#define RSISO_RG			0xc
23
24#define RSCTRL_KEY_MASK			0x0000ffff
25#define RSCTRL_RESET_MASK		BIT(16)
26#define RSCTRL_KEY			0x5a69
27
28#define RSMUX_OMODE_MASK		0xe
29#define RSMUX_OMODE_RESET_ON		0xa
30#define RSMUX_OMODE_RESET_OFF		0x0
31#define RSMUX_LOCK_MASK			0x1
32#define RSMUX_LOCK_SET			0x1
33
34#define RSCFG_RSTYPE_SOFT		0x300f
35#define RSCFG_RSTYPE_HARD		0x0
36
37#define WDT_MUX_NUMBER			0x4
38
39static int rspll_offset;
40static struct regmap *pllctrl_regs;
41
42/**
43 * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
44 * To be able to access to RSCTRL, RSCFG registers
45 * we have to write a key before
46 */
47static inline int rsctrl_enable_rspll_write(void)
48{
49	return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
50				  RSCTRL_KEY_MASK, RSCTRL_KEY);
51}
52
53static int rsctrl_restart_handler(struct notifier_block *this,
54				  unsigned long mode, void *cmd)
55{
56	/* enable write access to RSTCTRL */
57	rsctrl_enable_rspll_write();
58
59	/* reset the SOC */
60	regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
61			   RSCTRL_RESET_MASK, 0);
62
63	return NOTIFY_DONE;
64}
65
66static struct notifier_block rsctrl_restart_nb = {
67	.notifier_call = rsctrl_restart_handler,
68	.priority = 128,
69};
70
71static const struct of_device_id rsctrl_of_match[] = {
72	{.compatible = "ti,keystone-reset", },
73	{},
74};
75MODULE_DEVICE_TABLE(of, rsctrl_of_match);
76
77static int rsctrl_probe(struct platform_device *pdev)
78{
79	int i;
80	int ret;
81	u32 val;
82	unsigned int rg;
83	u32 rsmux_offset;
84	struct regmap *devctrl_regs;
85	struct device *dev = &pdev->dev;
86	struct device_node *np = dev->of_node;
87
88	if (!np)
89		return -ENODEV;
90
91	/* get regmaps */
92	pllctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-pll");
93	if (IS_ERR(pllctrl_regs))
94		return PTR_ERR(pllctrl_regs);
95
96	devctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-dev");
97	if (IS_ERR(devctrl_regs))
98		return PTR_ERR(devctrl_regs);
99
100	ret = of_property_read_u32_index(np, "ti,syscon-pll", 1, &rspll_offset);
101	if (ret) {
102		dev_err(dev, "couldn't read the reset pll offset!\n");
103		return -EINVAL;
104	}
105
106	ret = of_property_read_u32_index(np, "ti,syscon-dev", 1, &rsmux_offset);
107	if (ret) {
108		dev_err(dev, "couldn't read the rsmux offset!\n");
109		return -EINVAL;
110	}
111
112	/* set soft/hard reset */
113	val = of_property_read_bool(np, "ti,soft-reset");
114	val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
115
116	ret = rsctrl_enable_rspll_write();
117	if (ret)
118		return ret;
119
120	ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
121	if (ret)
122		return ret;
123
124	/* disable a reset isolation for all module clocks */
125	ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
126	if (ret)
127		return ret;
128
129	/* enable a reset for watchdogs from wdt-list */
130	for (i = 0; i < WDT_MUX_NUMBER; i++) {
131		ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
132		if (ret == -EOVERFLOW && !i) {
133			dev_err(dev, "ti,wdt-list property has to contain at"
134				"least one entry\n");
135			return -EINVAL;
136		} else if (ret) {
137			break;
138		}
139
140		if (val >= WDT_MUX_NUMBER) {
141			dev_err(dev, "ti,wdt-list property can contain "
142				"only numbers < 4\n");
143			return -EINVAL;
144		}
145
146		rg = rsmux_offset + val * 4;
147
148		ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
149					 RSMUX_OMODE_RESET_ON |
150					 RSMUX_LOCK_SET);
151		if (ret)
152			return ret;
153	}
154
155	ret = register_restart_handler(&rsctrl_restart_nb);
156	if (ret)
157		dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
158
159	return ret;
160}
161
162static struct platform_driver rsctrl_driver = {
163	.probe = rsctrl_probe,
164	.driver = {
165		.name = KBUILD_MODNAME,
166		.of_match_table = rsctrl_of_match,
167	},
168};
169module_platform_driver(rsctrl_driver);
170
171MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
172MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
173MODULE_ALIAS("platform:" KBUILD_MODNAME);
174