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