1 /*
2  * Watchdog driver for Ricoh RN5T618 PMIC
3  *
4  * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * version 2 as published by the Free Software Foundation.
9  *
10  * You should have received a copy of the GNU General Public License
11  * along with this program. If not, see <http://www.gnu.org/licenses/>.
12  */
13 
14 #include <linux/device.h>
15 #include <linux/mfd/rn5t618.h>
16 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/watchdog.h>
19 
20 #define DRIVER_NAME "rn5t618-wdt"
21 
22 static bool nowayout = WATCHDOG_NOWAYOUT;
23 static unsigned int timeout;
24 
25 module_param(timeout, uint, 0);
26 MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
27 
28 module_param(nowayout, bool, 0);
29 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
30 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
31 
32 struct rn5t618_wdt {
33 	struct watchdog_device wdt_dev;
34 	struct rn5t618 *rn5t618;
35 };
36 
37 /*
38  * This array encodes the values of WDOGTIM field for the supported
39  * watchdog expiration times. If the watchdog is not accessed before
40  * the timer expiration, the PMU generates an interrupt and if the CPU
41  * doesn't clear it within one second the system is restarted.
42  */
43 static const struct {
44 	u8 reg_val;
45 	unsigned int time;
46 } rn5t618_wdt_map[] = {
47 	{ 0, 1 },
48 	{ 1, 8 },
49 	{ 2, 32 },
50 	{ 3, 128 },
51 };
52 
53 static int rn5t618_wdt_set_timeout(struct watchdog_device *wdt_dev,
54 				   unsigned int t)
55 {
56 	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
57 	int ret, i;
58 
59 	for (i = 0; i < ARRAY_SIZE(rn5t618_wdt_map); i++) {
60 		if (rn5t618_wdt_map[i].time + 1 >= t)
61 			break;
62 	}
63 
64 	if (i == ARRAY_SIZE(rn5t618_wdt_map))
65 		return -EINVAL;
66 
67 	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
68 				 RN5T618_WATCHDOG_WDOGTIM_M,
69 				 rn5t618_wdt_map[i].reg_val);
70 	if (!ret)
71 		wdt_dev->timeout = rn5t618_wdt_map[i].time;
72 
73 	return ret;
74 }
75 
76 static int rn5t618_wdt_start(struct watchdog_device *wdt_dev)
77 {
78 	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
79 	int ret;
80 
81 	ret = rn5t618_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
82 	if (ret)
83 		return ret;
84 
85 	/* enable repower-on */
86 	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_REPCNT,
87 				 RN5T618_REPCNT_REPWRON,
88 				 RN5T618_REPCNT_REPWRON);
89 	if (ret)
90 		return ret;
91 
92 	/* enable watchdog */
93 	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
94 				 RN5T618_WATCHDOG_WDOGEN,
95 				 RN5T618_WATCHDOG_WDOGEN);
96 	if (ret)
97 		return ret;
98 
99 	/* enable watchdog interrupt */
100 	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIREN,
101 				  RN5T618_PWRIRQ_IR_WDOG,
102 				  RN5T618_PWRIRQ_IR_WDOG);
103 }
104 
105 static int rn5t618_wdt_stop(struct watchdog_device *wdt_dev)
106 {
107 	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
108 
109 	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
110 				  RN5T618_WATCHDOG_WDOGEN, 0);
111 }
112 
113 static int rn5t618_wdt_ping(struct watchdog_device *wdt_dev)
114 {
115 	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
116 	unsigned int val;
117 	int ret;
118 
119 	/* The counter is restarted after a R/W access to watchdog register */
120 	ret = regmap_read(wdt->rn5t618->regmap, RN5T618_WATCHDOG, &val);
121 	if (ret)
122 		return ret;
123 
124 	ret = regmap_write(wdt->rn5t618->regmap, RN5T618_WATCHDOG, val);
125 	if (ret)
126 		return ret;
127 
128 	/* Clear pending watchdog interrupt */
129 	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIRQ,
130 				  RN5T618_PWRIRQ_IR_WDOG, 0);
131 }
132 
133 static struct watchdog_info rn5t618_wdt_info = {
134 	.options	= WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
135 			  WDIOF_KEEPALIVEPING,
136 	.identity	= DRIVER_NAME,
137 };
138 
139 static struct watchdog_ops rn5t618_wdt_ops = {
140 	.owner          = THIS_MODULE,
141 	.start          = rn5t618_wdt_start,
142 	.stop           = rn5t618_wdt_stop,
143 	.ping           = rn5t618_wdt_ping,
144 	.set_timeout    = rn5t618_wdt_set_timeout,
145 };
146 
147 static int rn5t618_wdt_probe(struct platform_device *pdev)
148 {
149 	struct rn5t618 *rn5t618 = dev_get_drvdata(pdev->dev.parent);
150 	struct rn5t618_wdt *wdt;
151 	int min_timeout, max_timeout;
152 
153 	wdt = devm_kzalloc(&pdev->dev, sizeof(struct rn5t618_wdt), GFP_KERNEL);
154 	if (!wdt)
155 		return -ENOMEM;
156 
157 	min_timeout = rn5t618_wdt_map[0].time;
158 	max_timeout = rn5t618_wdt_map[ARRAY_SIZE(rn5t618_wdt_map) - 1].time;
159 
160 	wdt->rn5t618 = rn5t618;
161 	wdt->wdt_dev.info = &rn5t618_wdt_info;
162 	wdt->wdt_dev.ops = &rn5t618_wdt_ops;
163 	wdt->wdt_dev.min_timeout = min_timeout;
164 	wdt->wdt_dev.max_timeout = max_timeout;
165 	wdt->wdt_dev.timeout = max_timeout;
166 	wdt->wdt_dev.parent = &pdev->dev;
167 
168 	watchdog_set_drvdata(&wdt->wdt_dev, wdt);
169 	watchdog_init_timeout(&wdt->wdt_dev, timeout, &pdev->dev);
170 	watchdog_set_nowayout(&wdt->wdt_dev, nowayout);
171 
172 	platform_set_drvdata(pdev, wdt);
173 
174 	return watchdog_register_device(&wdt->wdt_dev);
175 }
176 
177 static int rn5t618_wdt_remove(struct platform_device *pdev)
178 {
179 	struct rn5t618_wdt *wdt = platform_get_drvdata(pdev);
180 
181 	watchdog_unregister_device(&wdt->wdt_dev);
182 
183 	return 0;
184 }
185 
186 static struct platform_driver rn5t618_wdt_driver = {
187 	.probe = rn5t618_wdt_probe,
188 	.remove = rn5t618_wdt_remove,
189 	.driver = {
190 		.name	= DRIVER_NAME,
191 	},
192 };
193 
194 module_platform_driver(rn5t618_wdt_driver);
195 
196 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
197 MODULE_DESCRIPTION("RN5T618 watchdog driver");
198 MODULE_LICENSE("GPL v2");
199