1 /*
2  * Watchdog driver for the UniPhier watchdog timer
3  *
4  * (c) Copyright 2014 Panasonic Corporation
5  * (c) Copyright 2016 Socionext Inc.
6  * All rights reserved.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/bitops.h>
19 #include <linux/mfd/syscon.h>
20 #include <linux/module.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/regmap.h>
24 #include <linux/watchdog.h>
25 
26 /* WDT timer setting register */
27 #define WDTTIMSET			0x3004
28 #define   WDTTIMSET_PERIOD_MASK		(0xf << 0)
29 #define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)
30 
31 /* WDT reset selection register */
32 #define WDTRSTSEL			0x3008
33 #define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)
34 #define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)
35 #define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)
36 
37 /* WDT control register */
38 #define WDTCTRL				0x300c
39 #define   WDTCTRL_STATUS		BIT(8)
40 #define   WDTCTRL_CLEAR			BIT(1)
41 #define   WDTCTRL_ENABLE		BIT(0)
42 
43 #define SEC_TO_WDTTIMSET_PRD(sec) \
44 		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
45 
46 #define WDTST_TIMEOUT			1000 /* usec */
47 
48 #define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */
49 #define WDT_PERIOD_MIN			1
50 #define WDT_PERIOD_MAX			128
51 
52 static unsigned int timeout = 0;
53 static bool nowayout = WATCHDOG_NOWAYOUT;
54 
55 struct uniphier_wdt_dev {
56 	struct watchdog_device wdt_dev;
57 	struct regmap	*regmap;
58 };
59 
60 /*
61  * UniPhier Watchdog operations
62  */
63 static int uniphier_watchdog_ping(struct watchdog_device *w)
64 {
65 	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
66 	unsigned int val;
67 	int ret;
68 
69 	/* Clear counter */
70 	ret = regmap_write_bits(wdev->regmap, WDTCTRL,
71 				WDTCTRL_CLEAR, WDTCTRL_CLEAR);
72 	if (!ret)
73 		/*
74 		 * As SoC specification, after clear counter,
75 		 * it needs to wait until counter status is 1.
76 		 */
77 		ret = regmap_read_poll_timeout(wdev->regmap, WDTCTRL, val,
78 					       (val & WDTCTRL_STATUS),
79 					       0, WDTST_TIMEOUT);
80 
81 	return ret;
82 }
83 
84 static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
85 {
86 	unsigned int val;
87 	int ret;
88 
89 	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
90 				       !(val & WDTCTRL_STATUS),
91 				       0, WDTST_TIMEOUT);
92 	if (ret)
93 		return ret;
94 
95 	/* Setup period */
96 	ret = regmap_write(regmap, WDTTIMSET,
97 			   SEC_TO_WDTTIMSET_PRD(sec));
98 	if (ret)
99 		return ret;
100 
101 	/* Enable and clear watchdog */
102 	ret = regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
103 	if (!ret)
104 		/*
105 		 * As SoC specification, after clear counter,
106 		 * it needs to wait until counter status is 1.
107 		 */
108 		ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
109 					       (val & WDTCTRL_STATUS),
110 					       0, WDTST_TIMEOUT);
111 
112 	return ret;
113 }
114 
115 static int __uniphier_watchdog_stop(struct regmap *regmap)
116 {
117 	/* Disable and stop watchdog */
118 	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
119 }
120 
121 static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
122 {
123 	int ret;
124 
125 	ret = __uniphier_watchdog_stop(regmap);
126 	if (ret)
127 		return ret;
128 
129 	return __uniphier_watchdog_start(regmap, sec);
130 }
131 
132 static int uniphier_watchdog_start(struct watchdog_device *w)
133 {
134 	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
135 	unsigned int tmp_timeout;
136 
137 	tmp_timeout = roundup_pow_of_two(w->timeout);
138 
139 	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
140 }
141 
142 static int uniphier_watchdog_stop(struct watchdog_device *w)
143 {
144 	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
145 
146 	return __uniphier_watchdog_stop(wdev->regmap);
147 }
148 
149 static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
150 					 unsigned int t)
151 {
152 	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
153 	unsigned int tmp_timeout;
154 	int ret;
155 
156 	tmp_timeout = roundup_pow_of_two(t);
157 	if (tmp_timeout == w->timeout)
158 		return 0;
159 
160 	if (watchdog_active(w)) {
161 		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
162 		if (ret)
163 			return ret;
164 	}
165 
166 	w->timeout = tmp_timeout;
167 
168 	return 0;
169 }
170 
171 /*
172  * Kernel Interfaces
173  */
174 static const struct watchdog_info uniphier_wdt_info = {
175 	.identity	= "uniphier-wdt",
176 	.options	= WDIOF_SETTIMEOUT |
177 			  WDIOF_KEEPALIVEPING |
178 			  WDIOF_MAGICCLOSE |
179 			  WDIOF_OVERHEAT,
180 };
181 
182 static const struct watchdog_ops uniphier_wdt_ops = {
183 	.owner		= THIS_MODULE,
184 	.start		= uniphier_watchdog_start,
185 	.stop		= uniphier_watchdog_stop,
186 	.ping		= uniphier_watchdog_ping,
187 	.set_timeout	= uniphier_watchdog_set_timeout,
188 };
189 
190 static int uniphier_wdt_probe(struct platform_device *pdev)
191 {
192 	struct device *dev = &pdev->dev;
193 	struct uniphier_wdt_dev *wdev;
194 	struct regmap *regmap;
195 	struct device_node *parent;
196 	int ret;
197 
198 	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
199 	if (!wdev)
200 		return -ENOMEM;
201 
202 	platform_set_drvdata(pdev, wdev);
203 
204 	parent = of_get_parent(dev->of_node); /* parent should be syscon node */
205 	regmap = syscon_node_to_regmap(parent);
206 	of_node_put(parent);
207 	if (IS_ERR(regmap))
208 		return PTR_ERR(regmap);
209 
210 	wdev->regmap = regmap;
211 	wdev->wdt_dev.info = &uniphier_wdt_info;
212 	wdev->wdt_dev.ops = &uniphier_wdt_ops;
213 	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
214 	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
215 	wdev->wdt_dev.parent = dev;
216 
217 	if (watchdog_init_timeout(&wdev->wdt_dev, timeout, dev) < 0) {
218 		wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
219 	}
220 	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
221 	watchdog_stop_on_reboot(&wdev->wdt_dev);
222 
223 	watchdog_set_drvdata(&wdev->wdt_dev, wdev);
224 
225 	uniphier_watchdog_stop(&wdev->wdt_dev);
226 	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
227 	if (ret)
228 		return ret;
229 
230 	ret = devm_watchdog_register_device(dev, &wdev->wdt_dev);
231 	if (ret)
232 		return ret;
233 
234 	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
235 		 wdev->wdt_dev.timeout, nowayout);
236 
237 	return 0;
238 }
239 
240 static const struct of_device_id uniphier_wdt_dt_ids[] = {
241 	{ .compatible = "socionext,uniphier-wdt" },
242 	{ /* sentinel */ }
243 };
244 MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
245 
246 static struct platform_driver uniphier_wdt_driver = {
247 	.probe		= uniphier_wdt_probe,
248 	.driver		= {
249 		.name		= "uniphier-wdt",
250 		.of_match_table	= uniphier_wdt_dt_ids,
251 	},
252 };
253 
254 module_platform_driver(uniphier_wdt_driver);
255 
256 module_param(timeout, uint, 0000);
257 MODULE_PARM_DESC(timeout,
258 	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
259 				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
260 
261 module_param(nowayout, bool, 0000);
262 MODULE_PARM_DESC(nowayout,
263 	"Watchdog cannot be stopped once started (default="
264 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
265 
266 MODULE_AUTHOR("Keiji Hayashibara <hayashibara.keiji@socionext.com>");
267 MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
268 MODULE_LICENSE("GPL v2");
269