1 /*
2  * Watchdog driver for Conexant Digicolor
3  *
4  * Copyright (C) 2015 Paradox Innovation Ltd.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the
8  * Free Software Foundation; either version 2 of the License, or (at your
9  * option) any later version.
10  */
11 
12 #include <linux/types.h>
13 #include <linux/module.h>
14 #include <linux/io.h>
15 #include <linux/delay.h>
16 #include <linux/clk.h>
17 #include <linux/watchdog.h>
18 #include <linux/reboot.h>
19 #include <linux/platform_device.h>
20 #include <linux/of_address.h>
21 
22 #define TIMER_A_CONTROL		0
23 #define TIMER_A_COUNT		4
24 
25 #define TIMER_A_ENABLE_COUNT	BIT(0)
26 #define TIMER_A_ENABLE_WATCHDOG	BIT(1)
27 
28 struct dc_wdt {
29 	void __iomem		*base;
30 	struct clk		*clk;
31 	struct notifier_block	restart_handler;
32 	spinlock_t		lock;
33 };
34 
35 static unsigned timeout;
36 module_param(timeout, uint, 0);
37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
38 
39 static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks)
40 {
41 	unsigned long flags;
42 
43 	spin_lock_irqsave(&wdt->lock, flags);
44 
45 	writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
46 	writel_relaxed(ticks, wdt->base + TIMER_A_COUNT);
47 	writel_relaxed(TIMER_A_ENABLE_COUNT | TIMER_A_ENABLE_WATCHDOG,
48 		       wdt->base + TIMER_A_CONTROL);
49 
50 	spin_unlock_irqrestore(&wdt->lock, flags);
51 }
52 
53 static int dc_restart_handler(struct notifier_block *this, unsigned long mode,
54 			      void *cmd)
55 {
56 	struct dc_wdt *wdt = container_of(this, struct dc_wdt, restart_handler);
57 
58 	dc_wdt_set(wdt, 1);
59 	/* wait for reset to assert... */
60 	mdelay(500);
61 
62 	return NOTIFY_DONE;
63 }
64 
65 static int dc_wdt_start(struct watchdog_device *wdog)
66 {
67 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
68 
69 	dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk));
70 
71 	return 0;
72 }
73 
74 static int dc_wdt_stop(struct watchdog_device *wdog)
75 {
76 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
77 
78 	writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
79 
80 	return 0;
81 }
82 
83 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
84 {
85 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
86 
87 	dc_wdt_set(wdt, t * clk_get_rate(wdt->clk));
88 	wdog->timeout = t;
89 
90 	return 0;
91 }
92 
93 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog)
94 {
95 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
96 	uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT);
97 
98 	return count / clk_get_rate(wdt->clk);
99 }
100 
101 static struct watchdog_ops dc_wdt_ops = {
102 	.owner		= THIS_MODULE,
103 	.start		= dc_wdt_start,
104 	.stop		= dc_wdt_stop,
105 	.set_timeout	= dc_wdt_set_timeout,
106 	.get_timeleft	= dc_wdt_get_timeleft,
107 };
108 
109 static struct watchdog_info dc_wdt_info = {
110 	.options	= WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
111 			| WDIOF_KEEPALIVEPING,
112 	.identity	= "Conexant Digicolor Watchdog",
113 };
114 
115 static struct watchdog_device dc_wdt_wdd = {
116 	.info		= &dc_wdt_info,
117 	.ops		= &dc_wdt_ops,
118 	.min_timeout	= 1,
119 };
120 
121 static int dc_wdt_probe(struct platform_device *pdev)
122 {
123 	struct device *dev = &pdev->dev;
124 	struct device_node *np = dev->of_node;
125 	struct dc_wdt *wdt;
126 	int ret;
127 
128 	wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
129 	if (!wdt)
130 		return -ENOMEM;
131 	platform_set_drvdata(pdev, wdt);
132 
133 	wdt->base = of_iomap(np, 0);
134 	if (!wdt->base) {
135 		dev_err(dev, "Failed to remap watchdog regs");
136 		return -ENODEV;
137 	}
138 
139 	wdt->clk = devm_clk_get(&pdev->dev, NULL);
140 	if (IS_ERR(wdt->clk)) {
141 		ret = PTR_ERR(wdt->clk);
142 		goto err_iounmap;
143 	}
144 	dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
145 	dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
146 
147 	spin_lock_init(&wdt->lock);
148 
149 	watchdog_set_drvdata(&dc_wdt_wdd, wdt);
150 	watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
151 	ret = watchdog_register_device(&dc_wdt_wdd);
152 	if (ret) {
153 		dev_err(dev, "Failed to register watchdog device");
154 		goto err_iounmap;
155 	}
156 
157 	wdt->restart_handler.notifier_call = dc_restart_handler;
158 	wdt->restart_handler.priority = 128;
159 	ret = register_restart_handler(&wdt->restart_handler);
160 	if (ret)
161 		dev_warn(&pdev->dev, "cannot register restart handler\n");
162 
163 	return 0;
164 
165 err_iounmap:
166 	iounmap(wdt->base);
167 	return ret;
168 }
169 
170 static int dc_wdt_remove(struct platform_device *pdev)
171 {
172 	struct dc_wdt *wdt = platform_get_drvdata(pdev);
173 
174 	unregister_restart_handler(&wdt->restart_handler);
175 	watchdog_unregister_device(&dc_wdt_wdd);
176 	iounmap(wdt->base);
177 
178 	return 0;
179 }
180 
181 static void dc_wdt_shutdown(struct platform_device *pdev)
182 {
183 	dc_wdt_stop(&dc_wdt_wdd);
184 }
185 
186 static const struct of_device_id dc_wdt_of_match[] = {
187 	{ .compatible = "cnxt,cx92755-wdt", },
188 	{},
189 };
190 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
191 
192 static struct platform_driver dc_wdt_driver = {
193 	.probe		= dc_wdt_probe,
194 	.remove		= dc_wdt_remove,
195 	.shutdown	= dc_wdt_shutdown,
196 	.driver = {
197 		.name =		"digicolor-wdt",
198 		.of_match_table = dc_wdt_of_match,
199 	},
200 };
201 module_platform_driver(dc_wdt_driver);
202 
203 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
204 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
205 MODULE_LICENSE("GPL");
206