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 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_SET 0x1
31
32 #define RSCFG_RSTYPE_SOFT 0x300f
33 #define RSCFG_RSTYPE_HARD 0x0
34
35 #define WDT_MUX_NUMBER 0x4
36
37 static int rspll_offset;
38 static struct regmap *pllctrl_regs;
39
40 /**
41 * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
42 * To be able to access to RSCTRL, RSCFG registers
43 * we have to write a key before
44 */
rsctrl_enable_rspll_write(void)45 static inline int rsctrl_enable_rspll_write(void)
46 {
47 return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
48 RSCTRL_KEY_MASK, RSCTRL_KEY);
49 }
50
rsctrl_restart_handler(struct sys_off_data * data)51 static int rsctrl_restart_handler(struct sys_off_data *data)
52 {
53 /* enable write access to RSTCTRL */
54 rsctrl_enable_rspll_write();
55
56 /* reset the SOC */
57 regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
58 RSCTRL_RESET_MASK, 0);
59
60 return NOTIFY_DONE;
61 }
62
63 static const struct of_device_id rsctrl_of_match[] = {
64 {.compatible = "ti,keystone-reset", },
65 {},
66 };
67 MODULE_DEVICE_TABLE(of, rsctrl_of_match);
68
rsctrl_probe(struct platform_device * pdev)69 static int rsctrl_probe(struct platform_device *pdev)
70 {
71 int i;
72 int ret;
73 u32 val;
74 unsigned int rg;
75 u32 rsmux_offset;
76 struct regmap *devctrl_regs;
77 struct device *dev = &pdev->dev;
78 struct device_node *np = dev->of_node;
79
80 if (!np)
81 return -ENODEV;
82
83 /* get regmaps */
84 pllctrl_regs = syscon_regmap_lookup_by_phandle_args(np, "ti,syscon-pll",
85 1, &rspll_offset);
86 if (IS_ERR(pllctrl_regs))
87 return PTR_ERR(pllctrl_regs);
88
89 devctrl_regs = syscon_regmap_lookup_by_phandle_args(np, "ti,syscon-dev",
90 1, &rsmux_offset);
91 if (IS_ERR(devctrl_regs))
92 return PTR_ERR(devctrl_regs);
93
94 /* set soft/hard reset */
95 val = of_property_read_bool(np, "ti,soft-reset");
96 val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
97
98 ret = rsctrl_enable_rspll_write();
99 if (ret)
100 return ret;
101
102 ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
103 if (ret)
104 return ret;
105
106 /* disable a reset isolation for all module clocks */
107 ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
108 if (ret)
109 return ret;
110
111 /* enable a reset for watchdogs from wdt-list */
112 for (i = 0; i < WDT_MUX_NUMBER; i++) {
113 ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
114 if (ret == -EOVERFLOW && !i) {
115 dev_err(dev, "ti,wdt-list property has to contain at"
116 "least one entry\n");
117 return -EINVAL;
118 } else if (ret) {
119 break;
120 }
121
122 if (val >= WDT_MUX_NUMBER) {
123 dev_err(dev, "ti,wdt-list property can contain "
124 "only numbers < 4\n");
125 return -EINVAL;
126 }
127
128 rg = rsmux_offset + val * 4;
129
130 ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
131 RSMUX_OMODE_RESET_ON |
132 RSMUX_LOCK_SET);
133 if (ret)
134 return ret;
135 }
136
137 ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART, 128,
138 rsctrl_restart_handler, NULL);
139 if (ret)
140 dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
141
142 return ret;
143 }
144
145 static struct platform_driver rsctrl_driver = {
146 .probe = rsctrl_probe,
147 .driver = {
148 .name = KBUILD_MODNAME,
149 .of_match_table = rsctrl_of_match,
150 },
151 };
152 module_platform_driver(rsctrl_driver);
153
154 MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
155 MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
156 MODULE_ALIAS("platform:" KBUILD_MODNAME);
157