1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Watchdog driver for Faraday Technology FTWDT010
4  *
5  * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
6  *
7  * Inspired by the out-of-tree drivers from OpenWRT:
8  * Copyright (C) 2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
9  */
10 
11 #include <linux/bitops.h>
12 #include <linux/init.h>
13 #include <linux/interrupt.h>
14 #include <linux/io.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/platform_device.h>
19 #include <linux/slab.h>
20 #include <linux/watchdog.h>
21 
22 #define FTWDT010_WDCOUNTER	0x0
23 #define FTWDT010_WDLOAD		0x4
24 #define FTWDT010_WDRESTART	0x8
25 #define FTWDT010_WDCR		0xC
26 
27 #define WDRESTART_MAGIC		0x5AB9
28 
29 #define WDCR_CLOCK_5MHZ		BIT(4)
30 #define WDCR_WDEXT		BIT(3)
31 #define WDCR_WDINTR		BIT(2)
32 #define WDCR_SYS_RST		BIT(1)
33 #define WDCR_ENABLE		BIT(0)
34 
35 #define WDT_CLOCK		5000000		/* 5 MHz */
36 
37 struct ftwdt010_wdt {
38 	struct watchdog_device	wdd;
39 	struct device		*dev;
40 	void __iomem		*base;
41 	bool			has_irq;
42 };
43 
44 static inline
45 struct ftwdt010_wdt *to_ftwdt010_wdt(struct watchdog_device *wdd)
46 {
47 	return container_of(wdd, struct ftwdt010_wdt, wdd);
48 }
49 
50 static void ftwdt010_enable(struct ftwdt010_wdt *gwdt,
51 			    unsigned int timeout,
52 			    bool need_irq)
53 {
54 	u32 enable;
55 
56 	writel(timeout * WDT_CLOCK, gwdt->base + FTWDT010_WDLOAD);
57 	writel(WDRESTART_MAGIC, gwdt->base + FTWDT010_WDRESTART);
58 	/* set clock before enabling */
59 	enable = WDCR_CLOCK_5MHZ | WDCR_SYS_RST;
60 	writel(enable, gwdt->base + FTWDT010_WDCR);
61 	if (need_irq)
62 		enable |= WDCR_WDINTR;
63 	enable |= WDCR_ENABLE;
64 	writel(enable, gwdt->base + FTWDT010_WDCR);
65 }
66 
67 static int ftwdt010_wdt_start(struct watchdog_device *wdd)
68 {
69 	struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);
70 
71 	ftwdt010_enable(gwdt, wdd->timeout, gwdt->has_irq);
72 	return 0;
73 }
74 
75 static int ftwdt010_wdt_stop(struct watchdog_device *wdd)
76 {
77 	struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);
78 
79 	writel(0, gwdt->base + FTWDT010_WDCR);
80 
81 	return 0;
82 }
83 
84 static int ftwdt010_wdt_ping(struct watchdog_device *wdd)
85 {
86 	struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);
87 
88 	writel(WDRESTART_MAGIC, gwdt->base + FTWDT010_WDRESTART);
89 
90 	return 0;
91 }
92 
93 static int ftwdt010_wdt_set_timeout(struct watchdog_device *wdd,
94 				  unsigned int timeout)
95 {
96 	wdd->timeout = timeout;
97 	if (watchdog_active(wdd))
98 		ftwdt010_wdt_start(wdd);
99 
100 	return 0;
101 }
102 
103 static int ftwdt010_wdt_restart(struct watchdog_device *wdd,
104 				unsigned long action, void *data)
105 {
106 	ftwdt010_enable(to_ftwdt010_wdt(wdd), 0, false);
107 	return 0;
108 }
109 
110 static irqreturn_t ftwdt010_wdt_interrupt(int irq, void *data)
111 {
112 	struct ftwdt010_wdt *gwdt = data;
113 
114 	watchdog_notify_pretimeout(&gwdt->wdd);
115 
116 	return IRQ_HANDLED;
117 }
118 
119 static const struct watchdog_ops ftwdt010_wdt_ops = {
120 	.start		= ftwdt010_wdt_start,
121 	.stop		= ftwdt010_wdt_stop,
122 	.ping		= ftwdt010_wdt_ping,
123 	.set_timeout	= ftwdt010_wdt_set_timeout,
124 	.restart	= ftwdt010_wdt_restart,
125 	.owner		= THIS_MODULE,
126 };
127 
128 static const struct watchdog_info ftwdt010_wdt_info = {
129 	.options	= WDIOF_KEEPALIVEPING
130 			| WDIOF_MAGICCLOSE
131 			| WDIOF_SETTIMEOUT,
132 	.identity	= KBUILD_MODNAME,
133 };
134 
135 
136 static int ftwdt010_wdt_probe(struct platform_device *pdev)
137 {
138 	struct device *dev = &pdev->dev;
139 	struct ftwdt010_wdt *gwdt;
140 	unsigned int reg;
141 	int irq;
142 	int ret;
143 
144 	gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
145 	if (!gwdt)
146 		return -ENOMEM;
147 
148 	gwdt->base = devm_platform_ioremap_resource(pdev, 0);
149 	if (IS_ERR(gwdt->base))
150 		return PTR_ERR(gwdt->base);
151 
152 	gwdt->dev = dev;
153 	gwdt->wdd.info = &ftwdt010_wdt_info;
154 	gwdt->wdd.ops = &ftwdt010_wdt_ops;
155 	gwdt->wdd.min_timeout = 1;
156 	gwdt->wdd.max_timeout = 0xFFFFFFFF / WDT_CLOCK;
157 	gwdt->wdd.parent = dev;
158 
159 	/*
160 	 * If 'timeout-sec' unspecified in devicetree, assume a 13 second
161 	 * default.
162 	 */
163 	gwdt->wdd.timeout = 13U;
164 	watchdog_init_timeout(&gwdt->wdd, 0, dev);
165 
166 	reg = readw(gwdt->base + FTWDT010_WDCR);
167 	if (reg & WDCR_ENABLE) {
168 		/* Watchdog was enabled by the bootloader, disable it. */
169 		reg &= ~WDCR_ENABLE;
170 		writel(reg, gwdt->base + FTWDT010_WDCR);
171 	}
172 
173 	irq = platform_get_irq(pdev, 0);
174 	if (irq > 0) {
175 		ret = devm_request_irq(dev, irq, ftwdt010_wdt_interrupt, 0,
176 				       "watchdog bark", gwdt);
177 		if (ret)
178 			return ret;
179 		gwdt->has_irq = true;
180 	}
181 
182 	ret = devm_watchdog_register_device(dev, &gwdt->wdd);
183 	if (ret)
184 		return ret;
185 
186 	/* Set up platform driver data */
187 	platform_set_drvdata(pdev, gwdt);
188 	dev_info(dev, "FTWDT010 watchdog driver enabled\n");
189 
190 	return 0;
191 }
192 
193 static int __maybe_unused ftwdt010_wdt_suspend(struct device *dev)
194 {
195 	struct ftwdt010_wdt *gwdt = dev_get_drvdata(dev);
196 	unsigned int reg;
197 
198 	reg = readw(gwdt->base + FTWDT010_WDCR);
199 	reg &= ~WDCR_ENABLE;
200 	writel(reg, gwdt->base + FTWDT010_WDCR);
201 
202 	return 0;
203 }
204 
205 static int __maybe_unused ftwdt010_wdt_resume(struct device *dev)
206 {
207 	struct ftwdt010_wdt *gwdt = dev_get_drvdata(dev);
208 	unsigned int reg;
209 
210 	if (watchdog_active(&gwdt->wdd)) {
211 		reg = readw(gwdt->base + FTWDT010_WDCR);
212 		reg |= WDCR_ENABLE;
213 		writel(reg, gwdt->base + FTWDT010_WDCR);
214 	}
215 
216 	return 0;
217 }
218 
219 static const struct dev_pm_ops ftwdt010_wdt_dev_pm_ops = {
220 	SET_SYSTEM_SLEEP_PM_OPS(ftwdt010_wdt_suspend,
221 				ftwdt010_wdt_resume)
222 };
223 
224 static const struct of_device_id ftwdt010_wdt_match[] = {
225 	{ .compatible = "faraday,ftwdt010" },
226 	{ .compatible = "cortina,gemini-watchdog" },
227 	{},
228 };
229 MODULE_DEVICE_TABLE(of, ftwdt010_wdt_match);
230 
231 static struct platform_driver ftwdt010_wdt_driver = {
232 	.probe		= ftwdt010_wdt_probe,
233 	.driver		= {
234 		.name	= "ftwdt010-wdt",
235 		.of_match_table = ftwdt010_wdt_match,
236 		.pm = &ftwdt010_wdt_dev_pm_ops,
237 	},
238 };
239 module_platform_driver(ftwdt010_wdt_driver);
240 MODULE_AUTHOR("Linus Walleij");
241 MODULE_DESCRIPTION("Watchdog driver for Faraday Technology FTWDT010");
242 MODULE_LICENSE("GPL");
243