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 	if (IS_ERR_OR_NULL(dir))
147 		return;
148 
149 	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
150 				&bcm_kona_fops))
151 		wdt->debugfs = dir;
152 	else
153 		debugfs_remove_recursive(dir);
154 }
155 
156 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
157 {
158 	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
159 
160 	if (wdt && wdt->debugfs) {
161 		debugfs_remove_recursive(wdt->debugfs);
162 		wdt->debugfs = NULL;
163 	}
164 }
165 
166 #else
167 
168 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
169 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
170 
171 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
172 
173 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
174 					unsigned mask, unsigned newval)
175 {
176 	int val;
177 	unsigned long flags;
178 	int ret = 0;
179 
180 	spin_lock_irqsave(&wdt->lock, flags);
181 
182 	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
183 	if (val < 0) {
184 		ret = val;
185 	} else {
186 		val &= ~mask;
187 		val |= newval;
188 		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
189 	}
190 
191 	spin_unlock_irqrestore(&wdt->lock, flags);
192 
193 	return ret;
194 }
195 
196 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
197 {
198 	if (wdt->resolution > SECWDOG_MAX_RES)
199 		return -EINVAL;
200 
201 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
202 					wdt->resolution << SECWDOG_CLKS_SHIFT);
203 }
204 
205 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
206 					unsigned watchdog_flags)
207 {
208 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
209 
210 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
211 					SECS_TO_TICKS(wdog->timeout, wdt) |
212 					watchdog_flags);
213 }
214 
215 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
216 	unsigned int t)
217 {
218 	wdog->timeout = t;
219 	return 0;
220 }
221 
222 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
223 {
224 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
225 	int val;
226 	unsigned long flags;
227 
228 	spin_lock_irqsave(&wdt->lock, flags);
229 	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
230 	spin_unlock_irqrestore(&wdt->lock, flags);
231 
232 	if (val < 0)
233 		return val;
234 
235 	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
236 }
237 
238 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
239 {
240 	return bcm_kona_wdt_set_timeout_reg(wdog,
241 					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
242 }
243 
244 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
245 {
246 	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
247 
248 	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
249 					    SECWDOG_SRSTEN_MASK, 0);
250 }
251 
252 static const struct watchdog_ops bcm_kona_wdt_ops = {
253 	.owner =	THIS_MODULE,
254 	.start =	bcm_kona_wdt_start,
255 	.stop =		bcm_kona_wdt_stop,
256 	.set_timeout =	bcm_kona_wdt_set_timeout,
257 	.get_timeleft =	bcm_kona_wdt_get_timeleft,
258 };
259 
260 static const struct watchdog_info bcm_kona_wdt_info = {
261 	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
262 			WDIOF_KEEPALIVEPING,
263 	.identity =	"Broadcom Kona Watchdog Timer",
264 };
265 
266 static struct watchdog_device bcm_kona_wdt_wdd = {
267 	.info =		&bcm_kona_wdt_info,
268 	.ops =		&bcm_kona_wdt_ops,
269 	.min_timeout =	1,
270 	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
271 	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
272 };
273 
274 static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
275 {
276 	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
277 }
278 
279 static int bcm_kona_wdt_probe(struct platform_device *pdev)
280 {
281 	struct device *dev = &pdev->dev;
282 	struct bcm_kona_wdt *wdt;
283 	struct resource *res;
284 	int ret;
285 
286 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
287 	if (!wdt)
288 		return -ENOMEM;
289 
290 	spin_lock_init(&wdt->lock);
291 
292 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
293 	wdt->base = devm_ioremap_resource(dev, res);
294 	if (IS_ERR(wdt->base))
295 		return -ENODEV;
296 
297 	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
298 	ret = bcm_kona_wdt_set_resolution_reg(wdt);
299 	if (ret) {
300 		dev_err(dev, "Failed to set resolution (error: %d)", ret);
301 		return ret;
302 	}
303 
304 	platform_set_drvdata(pdev, wdt);
305 	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
306 	bcm_kona_wdt_wdd.parent = &pdev->dev;
307 
308 	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
309 	if (ret) {
310 		dev_err(dev, "Failed set watchdog timeout");
311 		return ret;
312 	}
313 
314 	ret = watchdog_register_device(&bcm_kona_wdt_wdd);
315 	if (ret) {
316 		dev_err(dev, "Failed to register watchdog device");
317 		return ret;
318 	}
319 
320 	bcm_kona_wdt_debug_init(pdev);
321 	dev_dbg(dev, "Broadcom Kona Watchdog Timer");
322 
323 	return 0;
324 }
325 
326 static int bcm_kona_wdt_remove(struct platform_device *pdev)
327 {
328 	bcm_kona_wdt_debug_exit(pdev);
329 	bcm_kona_wdt_shutdown(pdev);
330 	watchdog_unregister_device(&bcm_kona_wdt_wdd);
331 	dev_dbg(&pdev->dev, "Watchdog driver disabled");
332 
333 	return 0;
334 }
335 
336 static const struct of_device_id bcm_kona_wdt_of_match[] = {
337 	{ .compatible = "brcm,kona-wdt", },
338 	{},
339 };
340 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
341 
342 static struct platform_driver bcm_kona_wdt_driver = {
343 	.driver = {
344 			.name = BCM_KONA_WDT_NAME,
345 			.of_match_table = bcm_kona_wdt_of_match,
346 		  },
347 	.probe = bcm_kona_wdt_probe,
348 	.remove = bcm_kona_wdt_remove,
349 	.shutdown = bcm_kona_wdt_shutdown,
350 };
351 
352 module_platform_driver(bcm_kona_wdt_driver);
353 
354 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
355 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
356 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
357 MODULE_LICENSE("GPL v2");
358