1 /*
2  * MOXA ART SoCs watchdog driver.
3  *
4  * Copyright (C) 2013 Jonas Jensen
5  *
6  * Jonas Jensen <jonas.jensen@gmail.com>
7  *
8  * This file is licensed under the terms of the GNU General Public
9  * License version 2.  This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  */
12 
13 #include <linux/clk.h>
14 #include <linux/io.h>
15 #include <linux/module.h>
16 #include <linux/mod_devicetable.h>
17 #include <linux/err.h>
18 #include <linux/kernel.h>
19 #include <linux/platform_device.h>
20 #include <linux/watchdog.h>
21 #include <linux/moduleparam.h>
22 
23 #define REG_COUNT			0x4
24 #define REG_MODE			0x8
25 #define REG_ENABLE			0xC
26 
27 struct moxart_wdt_dev {
28 	struct watchdog_device dev;
29 	void __iomem *base;
30 	unsigned int clock_frequency;
31 };
32 
33 static int heartbeat;
34 
moxart_wdt_restart(struct watchdog_device * wdt_dev,unsigned long action,void * data)35 static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
36 			      unsigned long action, void *data)
37 {
38 	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
39 
40 	writel(1, moxart_wdt->base + REG_COUNT);
41 	writel(0x5ab9, moxart_wdt->base + REG_MODE);
42 	writel(0x03, moxart_wdt->base + REG_ENABLE);
43 
44 	return 0;
45 }
46 
moxart_wdt_stop(struct watchdog_device * wdt_dev)47 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
48 {
49 	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
50 
51 	writel(0, moxart_wdt->base + REG_ENABLE);
52 
53 	return 0;
54 }
55 
moxart_wdt_start(struct watchdog_device * wdt_dev)56 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
57 {
58 	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
59 
60 	writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
61 	       moxart_wdt->base + REG_COUNT);
62 	writel(0x5ab9, moxart_wdt->base + REG_MODE);
63 	writel(0x03, moxart_wdt->base + REG_ENABLE);
64 
65 	return 0;
66 }
67 
moxart_wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int timeout)68 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
69 				  unsigned int timeout)
70 {
71 	wdt_dev->timeout = timeout;
72 
73 	return 0;
74 }
75 
76 static const struct watchdog_info moxart_wdt_info = {
77 	.identity       = "moxart-wdt",
78 	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
79 			  WDIOF_MAGICCLOSE,
80 };
81 
82 static const struct watchdog_ops moxart_wdt_ops = {
83 	.owner          = THIS_MODULE,
84 	.start          = moxart_wdt_start,
85 	.stop           = moxart_wdt_stop,
86 	.set_timeout    = moxart_wdt_set_timeout,
87 	.restart        = moxart_wdt_restart,
88 };
89 
moxart_wdt_probe(struct platform_device * pdev)90 static int moxart_wdt_probe(struct platform_device *pdev)
91 {
92 	struct moxart_wdt_dev *moxart_wdt;
93 	struct device *dev = &pdev->dev;
94 	struct clk *clk;
95 	int err;
96 	unsigned int max_timeout;
97 	bool nowayout = WATCHDOG_NOWAYOUT;
98 
99 	moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
100 	if (!moxart_wdt)
101 		return -ENOMEM;
102 
103 	platform_set_drvdata(pdev, moxart_wdt);
104 
105 	moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
106 	if (IS_ERR(moxart_wdt->base))
107 		return PTR_ERR(moxart_wdt->base);
108 
109 	clk = devm_clk_get(dev, NULL);
110 	if (IS_ERR(clk)) {
111 		pr_err("%s: of_clk_get failed\n", __func__);
112 		return PTR_ERR(clk);
113 	}
114 
115 	moxart_wdt->clock_frequency = clk_get_rate(clk);
116 	if (moxart_wdt->clock_frequency == 0) {
117 		pr_err("%s: incorrect clock frequency\n", __func__);
118 		return -EINVAL;
119 	}
120 
121 	max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
122 
123 	moxart_wdt->dev.info = &moxart_wdt_info;
124 	moxart_wdt->dev.ops = &moxart_wdt_ops;
125 	moxart_wdt->dev.timeout = max_timeout;
126 	moxart_wdt->dev.min_timeout = 1;
127 	moxart_wdt->dev.max_timeout = max_timeout;
128 	moxart_wdt->dev.parent = dev;
129 
130 	watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
131 	watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
132 	watchdog_set_restart_priority(&moxart_wdt->dev, 128);
133 
134 	watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
135 
136 	watchdog_stop_on_unregister(&moxart_wdt->dev);
137 	err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
138 	if (err)
139 		return err;
140 
141 	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
142 		moxart_wdt->dev.timeout, nowayout);
143 
144 	return 0;
145 }
146 
147 static const struct of_device_id moxart_watchdog_match[] = {
148 	{ .compatible = "moxa,moxart-watchdog" },
149 	{ },
150 };
151 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
152 
153 static struct platform_driver moxart_wdt_driver = {
154 	.probe      = moxart_wdt_probe,
155 	.driver     = {
156 		.name		= "moxart-watchdog",
157 		.of_match_table	= moxart_watchdog_match,
158 	},
159 };
160 module_platform_driver(moxart_wdt_driver);
161 
162 module_param(heartbeat, int, 0);
163 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
164 
165 MODULE_DESCRIPTION("MOXART watchdog driver");
166 MODULE_LICENSE("GPL");
167 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
168