1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2015 Broadcom Corporation
4  *
5  */
6 
7 #include <linux/clk.h>
8 #include <linux/init.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/pm.h>
14 #include <linux/watchdog.h>
15 
16 #define WDT_START_1		0xff00
17 #define WDT_START_2		0x00ff
18 #define WDT_STOP_1		0xee00
19 #define WDT_STOP_2		0x00ee
20 
21 #define WDT_TIMEOUT_REG		0x0
22 #define WDT_CMD_REG		0x4
23 
24 #define WDT_MIN_TIMEOUT		1 /* seconds */
25 #define WDT_DEFAULT_TIMEOUT	30 /* seconds */
26 #define WDT_DEFAULT_RATE	27000000
27 
28 struct bcm7038_watchdog {
29 	void __iomem		*base;
30 	struct watchdog_device	wdd;
31 	u32			rate;
32 	struct clk		*clk;
33 };
34 
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36 
37 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
38 {
39 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
40 	u32 timeout;
41 
42 	timeout = wdt->rate * wdog->timeout;
43 
44 	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
45 }
46 
47 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
48 {
49 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
50 
51 	writel(WDT_START_1, wdt->base + WDT_CMD_REG);
52 	writel(WDT_START_2, wdt->base + WDT_CMD_REG);
53 
54 	return 0;
55 }
56 
57 static int bcm7038_wdt_start(struct watchdog_device *wdog)
58 {
59 	bcm7038_wdt_set_timeout_reg(wdog);
60 	bcm7038_wdt_ping(wdog);
61 
62 	return 0;
63 }
64 
65 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
66 {
67 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
68 
69 	writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
70 	writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
71 
72 	return 0;
73 }
74 
75 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
76 				   unsigned int t)
77 {
78 	/* Can't modify timeout value if watchdog timer is running */
79 	bcm7038_wdt_stop(wdog);
80 	wdog->timeout = t;
81 	bcm7038_wdt_start(wdog);
82 
83 	return 0;
84 }
85 
86 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
87 {
88 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
89 	u32 time_left;
90 
91 	time_left = readl(wdt->base + WDT_CMD_REG);
92 
93 	return time_left / wdt->rate;
94 }
95 
96 static const struct watchdog_info bcm7038_wdt_info = {
97 	.identity	= "Broadcom BCM7038 Watchdog Timer",
98 	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
99 				WDIOF_MAGICCLOSE
100 };
101 
102 static const struct watchdog_ops bcm7038_wdt_ops = {
103 	.owner		= THIS_MODULE,
104 	.start		= bcm7038_wdt_start,
105 	.stop		= bcm7038_wdt_stop,
106 	.set_timeout	= bcm7038_wdt_set_timeout,
107 	.get_timeleft	= bcm7038_wdt_get_timeleft,
108 };
109 
110 static void bcm7038_clk_disable_unprepare(void *data)
111 {
112 	clk_disable_unprepare(data);
113 }
114 
115 static int bcm7038_wdt_probe(struct platform_device *pdev)
116 {
117 	struct device *dev = &pdev->dev;
118 	struct bcm7038_watchdog *wdt;
119 	int err;
120 
121 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
122 	if (!wdt)
123 		return -ENOMEM;
124 
125 	platform_set_drvdata(pdev, wdt);
126 
127 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
128 	if (IS_ERR(wdt->base))
129 		return PTR_ERR(wdt->base);
130 
131 	wdt->clk = devm_clk_get(dev, NULL);
132 	/* If unable to get clock, use default frequency */
133 	if (!IS_ERR(wdt->clk)) {
134 		err = clk_prepare_enable(wdt->clk);
135 		if (err)
136 			return err;
137 		err = devm_add_action_or_reset(dev,
138 					       bcm7038_clk_disable_unprepare,
139 					       wdt->clk);
140 		if (err)
141 			return err;
142 		wdt->rate = clk_get_rate(wdt->clk);
143 		/* Prevent divide-by-zero exception */
144 		if (!wdt->rate)
145 			wdt->rate = WDT_DEFAULT_RATE;
146 	} else {
147 		wdt->rate = WDT_DEFAULT_RATE;
148 		wdt->clk = NULL;
149 	}
150 
151 	wdt->wdd.info		= &bcm7038_wdt_info;
152 	wdt->wdd.ops		= &bcm7038_wdt_ops;
153 	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
154 	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
155 	wdt->wdd.max_timeout	= 0xffffffff / wdt->rate;
156 	wdt->wdd.parent		= dev;
157 	watchdog_set_drvdata(&wdt->wdd, wdt);
158 
159 	watchdog_stop_on_reboot(&wdt->wdd);
160 	watchdog_stop_on_unregister(&wdt->wdd);
161 	err = devm_watchdog_register_device(dev, &wdt->wdd);
162 	if (err)
163 		return err;
164 
165 	dev_info(dev, "Registered BCM7038 Watchdog\n");
166 
167 	return 0;
168 }
169 
170 #ifdef CONFIG_PM_SLEEP
171 static int bcm7038_wdt_suspend(struct device *dev)
172 {
173 	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
174 
175 	if (watchdog_active(&wdt->wdd))
176 		return bcm7038_wdt_stop(&wdt->wdd);
177 
178 	return 0;
179 }
180 
181 static int bcm7038_wdt_resume(struct device *dev)
182 {
183 	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
184 
185 	if (watchdog_active(&wdt->wdd))
186 		return bcm7038_wdt_start(&wdt->wdd);
187 
188 	return 0;
189 }
190 #endif
191 
192 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
193 			 bcm7038_wdt_resume);
194 
195 static const struct of_device_id bcm7038_wdt_match[] = {
196 	{ .compatible = "brcm,bcm7038-wdt" },
197 	{},
198 };
199 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
200 
201 static struct platform_driver bcm7038_wdt_driver = {
202 	.probe		= bcm7038_wdt_probe,
203 	.driver		= {
204 		.name		= "bcm7038-wdt",
205 		.of_match_table	= bcm7038_wdt_match,
206 		.pm		= &bcm7038_wdt_pm_ops,
207 	}
208 };
209 module_platform_driver(bcm7038_wdt_driver);
210 
211 module_param(nowayout, bool, 0);
212 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
213 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
214 MODULE_LICENSE("GPL");
215 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
216 MODULE_AUTHOR("Justin Chen");
217