1/*
2 * Copyright (C) 2013 Broadcom Corporation
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
7 *
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 */
13
14#include <linux/debugfs.h>
15#include <linux/delay.h>
16#include <linux/err.h>
17#include <linux/io.h>
18#include <linux/module.h>
19#include <linux/of_address.h>
20#include <linux/platform_device.h>
21#include <linux/watchdog.h>
22
23#define SECWDOG_CTRL_REG		0x00000000
24#define SECWDOG_COUNT_REG		0x00000004
25
26#define SECWDOG_RESERVED_MASK		0x1dffffff
27#define SECWDOG_WD_LOAD_FLAG		0x10000000
28#define SECWDOG_EN_MASK			0x08000000
29#define SECWDOG_SRSTEN_MASK		0x04000000
30#define SECWDOG_RES_MASK		0x00f00000
31#define SECWDOG_COUNT_MASK		0x000fffff
32
33#define SECWDOG_MAX_COUNT		SECWDOG_COUNT_MASK
34#define SECWDOG_CLKS_SHIFT		20
35#define SECWDOG_MAX_RES			15
36#define SECWDOG_DEFAULT_RESOLUTION	4
37#define SECWDOG_MAX_TRY			1000
38
39#define SECS_TO_TICKS(x, w)		((x) << (w)->resolution)
40#define TICKS_TO_SECS(x, w)		((x) >> (w)->resolution)
41
42#define BCM_KONA_WDT_NAME		"bcm_kona_wdt"
43
44struct bcm_kona_wdt {
45	void __iomem *base;
46	/*
47	 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
48	 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
49	 * resolution of 4 means one tick is 62.5ms.
50	 *
51	 * The watchdog counter is 20 bits. Depending on resolution, the maximum
52	 * counter value of 0xfffff expires after about 12 days (resolution 0)
53	 * down to only 32s (resolution 15). The default resolution of 4 gives
54	 * us a maximum of about 18 hours and 12 minutes before the watchdog
55	 * times out.
56	 */
57	int resolution;
58	spinlock_t lock;
59#ifdef CONFIG_BCM_KONA_WDT_DEBUG
60	unsigned long busy_count;
61	struct dentry *debugfs;
62#endif
63};
64
65static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
66{
67	uint32_t val;
68	unsigned count = 0;
69
70	/*
71	 * If the WD_LOAD_FLAG is set, the watchdog counter field is being
72	 * updated in hardware. Once the WD timer is updated in hardware, it
73	 * gets cleared.
74	 */
75	do {
76		if (unlikely(count > 1))
77			udelay(5);
78		val = readl_relaxed(wdt->base + offset);
79		count++;
80	} while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
81
82#ifdef CONFIG_BCM_KONA_WDT_DEBUG
83	/* Remember the maximum number iterations due to WD_LOAD_FLAG */
84	if (count > wdt->busy_count)
85		wdt->busy_count = count;
86#endif
87
88	/* This is the only place we return a negative value. */
89	if (val & SECWDOG_WD_LOAD_FLAG)
90		return -ETIMEDOUT;
91
92	/* We always mask out reserved bits. */
93	val &= SECWDOG_RESERVED_MASK;
94
95	return val;
96}
97
98#ifdef CONFIG_BCM_KONA_WDT_DEBUG
99
100static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
101{
102	int ctl_val, cur_val;
103	unsigned long flags;
104	struct bcm_kona_wdt *wdt = s->private;
105
106	if (!wdt) {
107		seq_puts(s, "No device pointer\n");
108		return 0;
109	}
110
111	spin_lock_irqsave(&wdt->lock, flags);
112	ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
113	cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
114	spin_unlock_irqrestore(&wdt->lock, flags);
115
116	if (ctl_val < 0 || cur_val < 0) {
117		seq_puts(s, "Error accessing hardware\n");
118	} else {
119		int ctl, cur, ctl_sec, cur_sec, res;
120
121		ctl = ctl_val & SECWDOG_COUNT_MASK;
122		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
123		cur = cur_val & SECWDOG_COUNT_MASK;
124		ctl_sec = TICKS_TO_SECS(ctl, wdt);
125		cur_sec = TICKS_TO_SECS(cur, wdt);
126		seq_printf(s,
127			   "Resolution: %d / %d\n"
128			   "Control: %d s / %d (%#x) ticks\n"
129			   "Current: %d s / %d (%#x) ticks\n"
130			   "Busy count: %lu\n",
131			   res, wdt->resolution,
132			   ctl_sec, ctl, ctl,
133			   cur_sec, cur, cur,
134			   wdt->busy_count);
135	}
136
137	return 0;
138}
139
140static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
141{
142	return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
143}
144
145static const struct file_operations bcm_kona_dbg_operations = {
146	.open		= bcm_kona_dbg_open,
147	.read		= seq_read,
148	.llseek		= seq_lseek,
149	.release	= single_release,
150};
151
152static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
153{
154	struct dentry *dir;
155	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
156
157	if (!wdt)
158		return;
159
160	wdt->debugfs = NULL;
161
162	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
163	if (IS_ERR_OR_NULL(dir))
164		return;
165
166	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
167				&bcm_kona_dbg_operations))
168		wdt->debugfs = dir;
169	else
170		debugfs_remove_recursive(dir);
171}
172
173static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
174{
175	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
176
177	if (wdt && wdt->debugfs) {
178		debugfs_remove_recursive(wdt->debugfs);
179		wdt->debugfs = NULL;
180	}
181}
182
183#else
184
185static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
186static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
187
188#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
189
190static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
191					unsigned mask, unsigned newval)
192{
193	int val;
194	unsigned long flags;
195	int ret = 0;
196
197	spin_lock_irqsave(&wdt->lock, flags);
198
199	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
200	if (val < 0) {
201		ret = val;
202	} else {
203		val &= ~mask;
204		val |= newval;
205		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
206	}
207
208	spin_unlock_irqrestore(&wdt->lock, flags);
209
210	return ret;
211}
212
213static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
214{
215	if (wdt->resolution > SECWDOG_MAX_RES)
216		return -EINVAL;
217
218	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
219					wdt->resolution << SECWDOG_CLKS_SHIFT);
220}
221
222static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
223					unsigned watchdog_flags)
224{
225	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
226
227	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
228					SECS_TO_TICKS(wdog->timeout, wdt) |
229					watchdog_flags);
230}
231
232static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
233	unsigned int t)
234{
235	wdog->timeout = t;
236	return 0;
237}
238
239static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
240{
241	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
242	int val;
243	unsigned long flags;
244
245	spin_lock_irqsave(&wdt->lock, flags);
246	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
247	spin_unlock_irqrestore(&wdt->lock, flags);
248
249	if (val < 0)
250		return val;
251
252	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
253}
254
255static int bcm_kona_wdt_start(struct watchdog_device *wdog)
256{
257	return bcm_kona_wdt_set_timeout_reg(wdog,
258					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
259}
260
261static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
262{
263	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
264
265	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
266					    SECWDOG_SRSTEN_MASK, 0);
267}
268
269static struct watchdog_ops bcm_kona_wdt_ops = {
270	.owner =	THIS_MODULE,
271	.start =	bcm_kona_wdt_start,
272	.stop =		bcm_kona_wdt_stop,
273	.set_timeout =	bcm_kona_wdt_set_timeout,
274	.get_timeleft =	bcm_kona_wdt_get_timeleft,
275};
276
277static struct watchdog_info bcm_kona_wdt_info = {
278	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
279			WDIOF_KEEPALIVEPING,
280	.identity =	"Broadcom Kona Watchdog Timer",
281};
282
283static struct watchdog_device bcm_kona_wdt_wdd = {
284	.info =		&bcm_kona_wdt_info,
285	.ops =		&bcm_kona_wdt_ops,
286	.min_timeout =	1,
287	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
288	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
289};
290
291static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
292{
293	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
294}
295
296static int bcm_kona_wdt_probe(struct platform_device *pdev)
297{
298	struct device *dev = &pdev->dev;
299	struct bcm_kona_wdt *wdt;
300	struct resource *res;
301	int ret;
302
303	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
304	if (!wdt)
305		return -ENOMEM;
306
307	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
308	wdt->base = devm_ioremap_resource(dev, res);
309	if (IS_ERR(wdt->base))
310		return -ENODEV;
311
312	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
313	ret = bcm_kona_wdt_set_resolution_reg(wdt);
314	if (ret) {
315		dev_err(dev, "Failed to set resolution (error: %d)", ret);
316		return ret;
317	}
318
319	spin_lock_init(&wdt->lock);
320	platform_set_drvdata(pdev, wdt);
321	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
322	bcm_kona_wdt_wdd.parent = &pdev->dev;
323
324	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
325	if (ret) {
326		dev_err(dev, "Failed set watchdog timeout");
327		return ret;
328	}
329
330	ret = watchdog_register_device(&bcm_kona_wdt_wdd);
331	if (ret) {
332		dev_err(dev, "Failed to register watchdog device");
333		return ret;
334	}
335
336	bcm_kona_wdt_debug_init(pdev);
337	dev_dbg(dev, "Broadcom Kona Watchdog Timer");
338
339	return 0;
340}
341
342static int bcm_kona_wdt_remove(struct platform_device *pdev)
343{
344	bcm_kona_wdt_debug_exit(pdev);
345	bcm_kona_wdt_shutdown(pdev);
346	watchdog_unregister_device(&bcm_kona_wdt_wdd);
347	dev_dbg(&pdev->dev, "Watchdog driver disabled");
348
349	return 0;
350}
351
352static const struct of_device_id bcm_kona_wdt_of_match[] = {
353	{ .compatible = "brcm,kona-wdt", },
354	{},
355};
356MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
357
358static struct platform_driver bcm_kona_wdt_driver = {
359	.driver = {
360			.name = BCM_KONA_WDT_NAME,
361			.of_match_table = bcm_kona_wdt_of_match,
362		  },
363	.probe = bcm_kona_wdt_probe,
364	.remove = bcm_kona_wdt_remove,
365	.shutdown = bcm_kona_wdt_shutdown,
366};
367
368module_platform_driver(bcm_kona_wdt_driver);
369
370MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
371MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
372MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
373MODULE_LICENSE("GPL v2");
374