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
39 static int rspll_offset;
40 static 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 */
rsctrl_enable_rspll_write(void)47 static 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
rsctrl_restart_handler(struct notifier_block * this,unsigned long mode,void * cmd)53 static 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
66 static struct notifier_block rsctrl_restart_nb = {
67 .notifier_call = rsctrl_restart_handler,
68 .priority = 128,
69 };
70
71 static const struct of_device_id rsctrl_of_match[] = {
72 {.compatible = "ti,keystone-reset", },
73 {},
74 };
75 MODULE_DEVICE_TABLE(of, rsctrl_of_match);
76
rsctrl_probe(struct platform_device * pdev)77 static 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
162 static struct platform_driver rsctrl_driver = {
163 .probe = rsctrl_probe,
164 .driver = {
165 .name = KBUILD_MODNAME,
166 .of_match_table = rsctrl_of_match,
167 },
168 };
169 module_platform_driver(rsctrl_driver);
170
171 MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
172 MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
173 MODULE_ALIAS("platform:" KBUILD_MODNAME);
174