1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
4  *  JZ4740 Watchdog driver
5  */
6 
7 #include <linux/mfd/ingenic-tcu.h>
8 #include <linux/mfd/syscon.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/types.h>
12 #include <linux/kernel.h>
13 #include <linux/watchdog.h>
14 #include <linux/platform_device.h>
15 #include <linux/io.h>
16 #include <linux/device.h>
17 #include <linux/clk.h>
18 #include <linux/slab.h>
19 #include <linux/err.h>
20 #include <linux/of.h>
21 #include <linux/regmap.h>
22 
23 #define DEFAULT_HEARTBEAT 5
24 #define MAX_HEARTBEAT     2048
25 
26 static bool nowayout = WATCHDOG_NOWAYOUT;
27 module_param(nowayout, bool, 0);
28 MODULE_PARM_DESC(nowayout,
29 		 "Watchdog cannot be stopped once started (default="
30 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
31 
32 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
33 module_param(heartbeat, uint, 0);
34 MODULE_PARM_DESC(heartbeat,
35 		"Watchdog heartbeat period in seconds from 1 to "
36 		__MODULE_STRING(MAX_HEARTBEAT) ", default "
37 		__MODULE_STRING(DEFAULT_HEARTBEAT));
38 
39 struct jz4740_wdt_drvdata {
40 	struct watchdog_device wdt;
41 	struct regmap *map;
42 	struct clk *clk;
43 	unsigned long clk_rate;
44 };
45 
jz4740_wdt_ping(struct watchdog_device * wdt_dev)46 static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)
47 {
48 	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
49 
50 	regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);
51 
52 	return 0;
53 }
54 
jz4740_wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int new_timeout)55 static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
56 				    unsigned int new_timeout)
57 {
58 	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
59 	u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);
60 	unsigned int tcer;
61 
62 	regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
63 	regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
64 
65 	regmap_write(drvdata->map, TCU_REG_WDT_TDR, timeout_value);
66 	regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);
67 
68 	if (tcer & TCU_WDT_TCER_TCEN)
69 		regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
70 
71 	wdt_dev->timeout = new_timeout;
72 	return 0;
73 }
74 
jz4740_wdt_start(struct watchdog_device * wdt_dev)75 static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
76 {
77 	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
78 	unsigned int tcer;
79 	int ret;
80 
81 	ret = clk_prepare_enable(drvdata->clk);
82 	if (ret)
83 		return ret;
84 
85 	regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
86 
87 	jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
88 
89 	/* Start watchdog if it wasn't started already */
90 	if (!(tcer & TCU_WDT_TCER_TCEN))
91 		regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
92 
93 	return 0;
94 }
95 
jz4740_wdt_stop(struct watchdog_device * wdt_dev)96 static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
97 {
98 	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
99 
100 	regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
101 	clk_disable_unprepare(drvdata->clk);
102 
103 	return 0;
104 }
105 
jz4740_wdt_restart(struct watchdog_device * wdt_dev,unsigned long action,void * data)106 static int jz4740_wdt_restart(struct watchdog_device *wdt_dev,
107 			      unsigned long action, void *data)
108 {
109 	wdt_dev->timeout = 0;
110 	jz4740_wdt_start(wdt_dev);
111 	return 0;
112 }
113 
114 static const struct watchdog_info jz4740_wdt_info = {
115 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
116 	.identity = "jz4740 Watchdog",
117 };
118 
119 static const struct watchdog_ops jz4740_wdt_ops = {
120 	.owner = THIS_MODULE,
121 	.start = jz4740_wdt_start,
122 	.stop = jz4740_wdt_stop,
123 	.ping = jz4740_wdt_ping,
124 	.set_timeout = jz4740_wdt_set_timeout,
125 	.restart = jz4740_wdt_restart,
126 };
127 
128 #ifdef CONFIG_OF
129 static const struct of_device_id jz4740_wdt_of_matches[] = {
130 	{ .compatible = "ingenic,jz4740-watchdog", },
131 	{ .compatible = "ingenic,jz4780-watchdog", },
132 	{ /* sentinel */ }
133 };
134 MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
135 #endif
136 
jz4740_wdt_probe(struct platform_device * pdev)137 static int jz4740_wdt_probe(struct platform_device *pdev)
138 {
139 	struct device *dev = &pdev->dev;
140 	struct jz4740_wdt_drvdata *drvdata;
141 	struct watchdog_device *jz4740_wdt;
142 	long rate;
143 	int ret;
144 
145 	drvdata = devm_kzalloc(dev, sizeof(struct jz4740_wdt_drvdata),
146 			       GFP_KERNEL);
147 	if (!drvdata)
148 		return -ENOMEM;
149 
150 	drvdata->clk = devm_clk_get(&pdev->dev, "wdt");
151 	if (IS_ERR(drvdata->clk)) {
152 		dev_err(&pdev->dev, "cannot find WDT clock\n");
153 		return PTR_ERR(drvdata->clk);
154 	}
155 
156 	/* Set smallest clock possible */
157 	rate = clk_round_rate(drvdata->clk, 1);
158 	if (rate < 0)
159 		return rate;
160 
161 	ret = clk_set_rate(drvdata->clk, rate);
162 	if (ret)
163 		return ret;
164 
165 	drvdata->clk_rate = rate;
166 	jz4740_wdt = &drvdata->wdt;
167 	jz4740_wdt->info = &jz4740_wdt_info;
168 	jz4740_wdt->ops = &jz4740_wdt_ops;
169 	jz4740_wdt->min_timeout = 1;
170 	jz4740_wdt->max_timeout = 0xffff / rate;
171 	jz4740_wdt->timeout = clamp(heartbeat,
172 				    jz4740_wdt->min_timeout,
173 				    jz4740_wdt->max_timeout);
174 	jz4740_wdt->parent = dev;
175 	watchdog_set_nowayout(jz4740_wdt, nowayout);
176 	watchdog_set_drvdata(jz4740_wdt, drvdata);
177 
178 	drvdata->map = device_node_to_regmap(dev->parent->of_node);
179 	if (IS_ERR(drvdata->map)) {
180 		dev_err(dev, "regmap not found\n");
181 		return PTR_ERR(drvdata->map);
182 	}
183 
184 	return devm_watchdog_register_device(dev, &drvdata->wdt);
185 }
186 
187 static struct platform_driver jz4740_wdt_driver = {
188 	.probe = jz4740_wdt_probe,
189 	.driver = {
190 		.name = "jz4740-wdt",
191 		.of_match_table = of_match_ptr(jz4740_wdt_of_matches),
192 	},
193 };
194 
195 module_platform_driver(jz4740_wdt_driver);
196 
197 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
198 MODULE_DESCRIPTION("jz4740 Watchdog Driver");
199 MODULE_LICENSE("GPL");
200 MODULE_ALIAS("platform:jz4740-wdt");
201