1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2013 Broadcom Corporation
4  *
5  */
6 
7 #include <linux/debugfs.h>
8 #include <linux/delay.h>
9 #include <linux/err.h>
10 #include <linux/io.h>
11 #include <linux/module.h>
12 #include <linux/of_address.h>
13 #include <linux/platform_device.h>
14 #include <linux/watchdog.h>
15 
16 #define SECWDOG_CTRL_REG		0x00000000
17 #define SECWDOG_COUNT_REG		0x00000004
18 
19 #define SECWDOG_RESERVED_MASK		0x1dffffff
20 #define SECWDOG_WD_LOAD_FLAG		0x10000000
21 #define SECWDOG_EN_MASK			0x08000000
22 #define SECWDOG_SRSTEN_MASK		0x04000000
23 #define SECWDOG_RES_MASK		0x00f00000
24 #define SECWDOG_COUNT_MASK		0x000fffff
25 
26 #define SECWDOG_MAX_COUNT		SECWDOG_COUNT_MASK
27 #define SECWDOG_CLKS_SHIFT		20
28 #define SECWDOG_MAX_RES			15
29 #define SECWDOG_DEFAULT_RESOLUTION	4
30 #define SECWDOG_MAX_TRY			1000
31 
32 #define SECS_TO_TICKS(x, w)		((x) << (w)->resolution)
33 #define TICKS_TO_SECS(x, w)		((x) >> (w)->resolution)
34 
35 #define BCM_KONA_WDT_NAME		"bcm_kona_wdt"
36 
37 struct bcm_kona_wdt {
38 	void __iomem *base;
39 	/*
40 	 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
41 	 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
42 	 * resolution of 4 means one tick is 62.5ms.
43 	 *
44 	 * The watchdog counter is 20 bits. Depending on resolution, the maximum
45 	 * counter value of 0xfffff expires after about 12 days (resolution 0)
46 	 * down to only 32s (resolution 15). The default resolution of 4 gives
47 	 * us a maximum of about 18 hours and 12 minutes before the watchdog
48 	 * times out.
49 	 */
50 	int resolution;
51 	spinlock_t lock;
52 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
53 	unsigned long busy_count;
54 	struct dentry *debugfs;
55 #endif
56 };
57 
58 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
59 {
60 	uint32_t val;
61 	unsigned count = 0;
62 
63 	/*
64 	 * If the WD_LOAD_FLAG is set, the watchdog counter field is being
65 	 * updated in hardware. Once the WD timer is updated in hardware, it
66 	 * gets cleared.
67 	 */
68 	do {
69 		if (unlikely(count > 1))
70 			udelay(5);
71 		val = readl_relaxed(wdt->base + offset);
72 		count++;
73 	} while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
74 
75 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
76 	/* Remember the maximum number iterations due to WD_LOAD_FLAG */
77 	if (count > wdt->busy_count)
78 		wdt->busy_count = count;
79 #endif
80 
81 	/* This is the only place we return a negative value. */
82 	if (val & SECWDOG_WD_LOAD_FLAG)
83 		return -ETIMEDOUT;
84 
85 	/* We always mask out reserved bits. */
86 	val &= SECWDOG_RESERVED_MASK;
87 
88 	return val;
89 }
90 
91 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
92 
93 static int bcm_kona_show(struct seq_file *s, void *data)
94 {
95 	int ctl_val, cur_val;
96 	unsigned long flags;
97 	struct bcm_kona_wdt *wdt = s->private;
98 
99 	if (!wdt) {
100 		seq_puts(s, "No device pointer\n");
101 		return 0;
102 	}
103 
104 	spin_lock_irqsave(&wdt->lock, flags);
105 	ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
106 	cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
107 	spin_unlock_irqrestore(&wdt->lock, flags);
108 
109 	if (ctl_val < 0 || cur_val < 0) {
110 		seq_puts(s, "Error accessing hardware\n");
111 	} else {
112 		int ctl, cur, ctl_sec, cur_sec, res;
113 
114 		ctl = ctl_val & SECWDOG_COUNT_MASK;
115 		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
116 		cur = cur_val & SECWDOG_COUNT_MASK;
117 		ctl_sec = TICKS_TO_SECS(ctl, wdt);
118 		cur_sec = TICKS_TO_SECS(cur, wdt);
119 		seq_printf(s,
120 			   "Resolution: %d / %d\n"
121 			   "Control: %d s / %d (%#x) ticks\n"
122 			   "Current: %d s / %d (%#x) ticks\n"
123 			   "Busy count: %lu\n",
124 			   res, wdt->resolution,
125 			   ctl_sec, ctl, ctl,
126 			   cur_sec, cur, cur,
127 			   wdt->busy_count);
128 	}
129 
130 	return 0;
131 }
132 
133 DEFINE_SHOW_ATTRIBUTE(bcm_kona);
134 
135 static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
136 {
137 	struct dentry *dir;
138 	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
139 
140 	if (!wdt)
141 		return;
142 
143 	wdt->debugfs = NULL;
144 
145 	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
146 
147 	debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
148 			    &bcm_kona_fops);
149 	wdt->debugfs = dir;
150 }
151 
152 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
153 {
154 	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
155 
156 	if (wdt)
157 		debugfs_remove_recursive(wdt->debugfs);
158 }
159 
160 #else
161 
162 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
163 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
164 
165 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
166 
167 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
168 					unsigned mask, unsigned newval)
169 {
170 	int val;
171 	unsigned long flags;
172 	int ret = 0;
173 
174 	spin_lock_irqsave(&wdt->lock, flags);
175 
176 	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
177 	if (val < 0) {
178 		ret = val;
179 	} else {
180 		val &= ~mask;
181 		val |= newval;
182 		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
183 	}
184 
185 	spin_unlock_irqrestore(&wdt->lock, flags);
186 
187 	return ret;
188 }
189 
190 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
191 {
192 	if (wdt->resolution > SECWDOG_MAX_RES)
193 		return -EINVAL;
194 
195 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
196 					wdt->resolution << SECWDOG_CLKS_SHIFT);
197 }
198 
199 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
200 					unsigned watchdog_flags)
201 {
202 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
203 
204 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
205 					SECS_TO_TICKS(wdog->timeout, wdt) |
206 					watchdog_flags);
207 }
208 
209 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
210 	unsigned int t)
211 {
212 	wdog->timeout = t;
213 	return 0;
214 }
215 
216 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
217 {
218 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
219 	int val;
220 	unsigned long flags;
221 
222 	spin_lock_irqsave(&wdt->lock, flags);
223 	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
224 	spin_unlock_irqrestore(&wdt->lock, flags);
225 
226 	if (val < 0)
227 		return val;
228 
229 	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
230 }
231 
232 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
233 {
234 	return bcm_kona_wdt_set_timeout_reg(wdog,
235 					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
236 }
237 
238 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
239 {
240 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
241 
242 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
243 					    SECWDOG_SRSTEN_MASK, 0);
244 }
245 
246 static const struct watchdog_ops bcm_kona_wdt_ops = {
247 	.owner =	THIS_MODULE,
248 	.start =	bcm_kona_wdt_start,
249 	.stop =		bcm_kona_wdt_stop,
250 	.set_timeout =	bcm_kona_wdt_set_timeout,
251 	.get_timeleft =	bcm_kona_wdt_get_timeleft,
252 };
253 
254 static const struct watchdog_info bcm_kona_wdt_info = {
255 	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
256 			WDIOF_KEEPALIVEPING,
257 	.identity =	"Broadcom Kona Watchdog Timer",
258 };
259 
260 static struct watchdog_device bcm_kona_wdt_wdd = {
261 	.info =		&bcm_kona_wdt_info,
262 	.ops =		&bcm_kona_wdt_ops,
263 	.min_timeout =	1,
264 	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
265 	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
266 };
267 
268 static int bcm_kona_wdt_probe(struct platform_device *pdev)
269 {
270 	struct device *dev = &pdev->dev;
271 	struct bcm_kona_wdt *wdt;
272 	int ret;
273 
274 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
275 	if (!wdt)
276 		return -ENOMEM;
277 
278 	spin_lock_init(&wdt->lock);
279 
280 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
281 	if (IS_ERR(wdt->base))
282 		return PTR_ERR(wdt->base);
283 
284 	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
285 	ret = bcm_kona_wdt_set_resolution_reg(wdt);
286 	if (ret) {
287 		dev_err(dev, "Failed to set resolution (error: %d)", ret);
288 		return ret;
289 	}
290 
291 	platform_set_drvdata(pdev, wdt);
292 	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
293 	bcm_kona_wdt_wdd.parent = dev;
294 
295 	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
296 	if (ret) {
297 		dev_err(dev, "Failed set watchdog timeout");
298 		return ret;
299 	}
300 
301 	watchdog_stop_on_reboot(&bcm_kona_wdt_wdd);
302 	watchdog_stop_on_unregister(&bcm_kona_wdt_wdd);
303 	ret = devm_watchdog_register_device(dev, &bcm_kona_wdt_wdd);
304 	if (ret)
305 		return ret;
306 
307 	bcm_kona_wdt_debug_init(pdev);
308 	dev_dbg(dev, "Broadcom Kona Watchdog Timer");
309 
310 	return 0;
311 }
312 
313 static int bcm_kona_wdt_remove(struct platform_device *pdev)
314 {
315 	bcm_kona_wdt_debug_exit(pdev);
316 	dev_dbg(&pdev->dev, "Watchdog driver disabled");
317 
318 	return 0;
319 }
320 
321 static const struct of_device_id bcm_kona_wdt_of_match[] = {
322 	{ .compatible = "brcm,kona-wdt", },
323 	{},
324 };
325 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
326 
327 static struct platform_driver bcm_kona_wdt_driver = {
328 	.driver = {
329 			.name = BCM_KONA_WDT_NAME,
330 			.of_match_table = bcm_kona_wdt_of_match,
331 		  },
332 	.probe = bcm_kona_wdt_probe,
333 	.remove = bcm_kona_wdt_remove,
334 };
335 
336 module_platform_driver(bcm_kona_wdt_driver);
337 
338 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
339 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
340 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
341 MODULE_LICENSE("GPL v2");
342