1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Watchdog driver for Conexant Digicolor
4  *
5  * Copyright (C) 2015 Paradox Innovation Ltd.
6  *
7  */
8 
9 #include <linux/types.h>
10 #include <linux/module.h>
11 #include <linux/io.h>
12 #include <linux/delay.h>
13 #include <linux/clk.h>
14 #include <linux/watchdog.h>
15 #include <linux/platform_device.h>
16 #include <linux/of_address.h>
17 
18 #define TIMER_A_CONTROL		0
19 #define TIMER_A_COUNT		4
20 
21 #define TIMER_A_ENABLE_COUNT	BIT(0)
22 #define TIMER_A_ENABLE_WATCHDOG	BIT(1)
23 
24 struct dc_wdt {
25 	void __iomem		*base;
26 	struct clk		*clk;
27 	spinlock_t		lock;
28 };
29 
30 static unsigned timeout;
31 module_param(timeout, uint, 0);
32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
33 
34 static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks)
35 {
36 	unsigned long flags;
37 
38 	spin_lock_irqsave(&wdt->lock, flags);
39 
40 	writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
41 	writel_relaxed(ticks, wdt->base + TIMER_A_COUNT);
42 	writel_relaxed(TIMER_A_ENABLE_COUNT | TIMER_A_ENABLE_WATCHDOG,
43 		       wdt->base + TIMER_A_CONTROL);
44 
45 	spin_unlock_irqrestore(&wdt->lock, flags);
46 }
47 
48 static int dc_wdt_restart(struct watchdog_device *wdog, unsigned long action,
49 			  void *data)
50 {
51 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
52 
53 	dc_wdt_set(wdt, 1);
54 	/* wait for reset to assert... */
55 	mdelay(500);
56 
57 	return 0;
58 }
59 
60 static int dc_wdt_start(struct watchdog_device *wdog)
61 {
62 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
63 
64 	dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk));
65 
66 	return 0;
67 }
68 
69 static int dc_wdt_stop(struct watchdog_device *wdog)
70 {
71 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
72 
73 	writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
74 
75 	return 0;
76 }
77 
78 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
79 {
80 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
81 
82 	dc_wdt_set(wdt, t * clk_get_rate(wdt->clk));
83 	wdog->timeout = t;
84 
85 	return 0;
86 }
87 
88 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog)
89 {
90 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
91 	uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT);
92 
93 	return count / clk_get_rate(wdt->clk);
94 }
95 
96 static const struct watchdog_ops dc_wdt_ops = {
97 	.owner		= THIS_MODULE,
98 	.start		= dc_wdt_start,
99 	.stop		= dc_wdt_stop,
100 	.set_timeout	= dc_wdt_set_timeout,
101 	.get_timeleft	= dc_wdt_get_timeleft,
102 	.restart        = dc_wdt_restart,
103 };
104 
105 static const struct watchdog_info dc_wdt_info = {
106 	.options	= WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
107 			| WDIOF_KEEPALIVEPING,
108 	.identity	= "Conexant Digicolor Watchdog",
109 };
110 
111 static struct watchdog_device dc_wdt_wdd = {
112 	.info		= &dc_wdt_info,
113 	.ops		= &dc_wdt_ops,
114 	.min_timeout	= 1,
115 };
116 
117 static int dc_wdt_probe(struct platform_device *pdev)
118 {
119 	struct resource *res;
120 	struct device *dev = &pdev->dev;
121 	struct dc_wdt *wdt;
122 	int ret;
123 
124 	wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
125 	if (!wdt)
126 		return -ENOMEM;
127 
128 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
129 	wdt->base = devm_ioremap_resource(dev, res);
130 	if (IS_ERR(wdt->base))
131 		return PTR_ERR(wdt->base);
132 
133 	wdt->clk = devm_clk_get(dev, NULL);
134 	if (IS_ERR(wdt->clk))
135 		return PTR_ERR(wdt->clk);
136 	dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
137 	dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
138 	dc_wdt_wdd.parent = dev;
139 
140 	spin_lock_init(&wdt->lock);
141 
142 	watchdog_set_drvdata(&dc_wdt_wdd, wdt);
143 	watchdog_set_restart_priority(&dc_wdt_wdd, 128);
144 	watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
145 	watchdog_stop_on_reboot(&dc_wdt_wdd);
146 	ret = devm_watchdog_register_device(dev, &dc_wdt_wdd);
147 	if (ret) {
148 		dev_err(dev, "Failed to register watchdog device");
149 		return ret;
150 	}
151 
152 	return 0;
153 }
154 
155 static const struct of_device_id dc_wdt_of_match[] = {
156 	{ .compatible = "cnxt,cx92755-wdt", },
157 	{},
158 };
159 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
160 
161 static struct platform_driver dc_wdt_driver = {
162 	.probe		= dc_wdt_probe,
163 	.driver = {
164 		.name =		"digicolor-wdt",
165 		.of_match_table = dc_wdt_of_match,
166 	},
167 };
168 module_platform_driver(dc_wdt_driver);
169 
170 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
171 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
172 MODULE_LICENSE("GPL");
173