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, ret;
103	unsigned long flags;
104	struct bcm_kona_wdt *wdt = s->private;
105
106	if (!wdt)
107		return seq_puts(s, "No device pointer\n");
108
109	spin_lock_irqsave(&wdt->lock, flags);
110	ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
111	cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
112	spin_unlock_irqrestore(&wdt->lock, flags);
113
114	if (ctl_val < 0 || cur_val < 0) {
115		ret = seq_puts(s, "Error accessing hardware\n");
116	} else {
117		int ctl, cur, ctl_sec, cur_sec, res;
118
119		ctl = ctl_val & SECWDOG_COUNT_MASK;
120		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
121		cur = cur_val & SECWDOG_COUNT_MASK;
122		ctl_sec = TICKS_TO_SECS(ctl, wdt);
123		cur_sec = TICKS_TO_SECS(cur, wdt);
124		ret = seq_printf(s, "Resolution: %d / %d\n"
125				"Control: %d s / %d (%#x) ticks\n"
126				"Current: %d s / %d (%#x) ticks\n"
127				"Busy count: %lu\n", res,
128				wdt->resolution, ctl_sec, ctl, ctl, cur_sec,
129				cur, cur, wdt->busy_count);
130	}
131
132	return ret;
133}
134
135static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
136{
137	return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
138}
139
140static const struct file_operations bcm_kona_dbg_operations = {
141	.open		= bcm_kona_dbg_open,
142	.read		= seq_read,
143	.llseek		= seq_lseek,
144	.release	= single_release,
145};
146
147static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
148{
149	struct dentry *dir;
150	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
151
152	if (!wdt)
153		return;
154
155	wdt->debugfs = NULL;
156
157	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
158	if (IS_ERR_OR_NULL(dir))
159		return;
160
161	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
162				&bcm_kona_dbg_operations))
163		wdt->debugfs = dir;
164	else
165		debugfs_remove_recursive(dir);
166}
167
168static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
169{
170	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
171
172	if (wdt && wdt->debugfs) {
173		debugfs_remove_recursive(wdt->debugfs);
174		wdt->debugfs = NULL;
175	}
176}
177
178#else
179
180static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
181static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
182
183#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
184
185static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
186					unsigned mask, unsigned newval)
187{
188	int val;
189	unsigned long flags;
190	int ret = 0;
191
192	spin_lock_irqsave(&wdt->lock, flags);
193
194	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
195	if (val < 0) {
196		ret = val;
197	} else {
198		val &= ~mask;
199		val |= newval;
200		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
201	}
202
203	spin_unlock_irqrestore(&wdt->lock, flags);
204
205	return ret;
206}
207
208static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
209{
210	if (wdt->resolution > SECWDOG_MAX_RES)
211		return -EINVAL;
212
213	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
214					wdt->resolution << SECWDOG_CLKS_SHIFT);
215}
216
217static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
218					unsigned watchdog_flags)
219{
220	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
221
222	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
223					SECS_TO_TICKS(wdog->timeout, wdt) |
224					watchdog_flags);
225}
226
227static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
228	unsigned int t)
229{
230	wdog->timeout = t;
231	return 0;
232}
233
234static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
235{
236	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
237	int val;
238	unsigned long flags;
239
240	spin_lock_irqsave(&wdt->lock, flags);
241	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
242	spin_unlock_irqrestore(&wdt->lock, flags);
243
244	if (val < 0)
245		return val;
246
247	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
248}
249
250static int bcm_kona_wdt_start(struct watchdog_device *wdog)
251{
252	return bcm_kona_wdt_set_timeout_reg(wdog,
253					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
254}
255
256static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
257{
258	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
259
260	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
261					    SECWDOG_SRSTEN_MASK, 0);
262}
263
264static struct watchdog_ops bcm_kona_wdt_ops = {
265	.owner =	THIS_MODULE,
266	.start =	bcm_kona_wdt_start,
267	.stop =		bcm_kona_wdt_stop,
268	.set_timeout =	bcm_kona_wdt_set_timeout,
269	.get_timeleft =	bcm_kona_wdt_get_timeleft,
270};
271
272static struct watchdog_info bcm_kona_wdt_info = {
273	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
274			WDIOF_KEEPALIVEPING,
275	.identity =	"Broadcom Kona Watchdog Timer",
276};
277
278static struct watchdog_device bcm_kona_wdt_wdd = {
279	.info =		&bcm_kona_wdt_info,
280	.ops =		&bcm_kona_wdt_ops,
281	.min_timeout =	1,
282	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
283	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
284};
285
286static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
287{
288	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
289}
290
291static int bcm_kona_wdt_probe(struct platform_device *pdev)
292{
293	struct device *dev = &pdev->dev;
294	struct bcm_kona_wdt *wdt;
295	struct resource *res;
296	int ret;
297
298	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
299	if (!wdt)
300		return -ENOMEM;
301
302	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
303	wdt->base = devm_ioremap_resource(dev, res);
304	if (IS_ERR(wdt->base))
305		return -ENODEV;
306
307	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
308	ret = bcm_kona_wdt_set_resolution_reg(wdt);
309	if (ret) {
310		dev_err(dev, "Failed to set resolution (error: %d)", ret);
311		return ret;
312	}
313
314	spin_lock_init(&wdt->lock);
315	platform_set_drvdata(pdev, wdt);
316	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
317
318	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
319	if (ret) {
320		dev_err(dev, "Failed set watchdog timeout");
321		return ret;
322	}
323
324	ret = watchdog_register_device(&bcm_kona_wdt_wdd);
325	if (ret) {
326		dev_err(dev, "Failed to register watchdog device");
327		return ret;
328	}
329
330	bcm_kona_wdt_debug_init(pdev);
331	dev_dbg(dev, "Broadcom Kona Watchdog Timer");
332
333	return 0;
334}
335
336static int bcm_kona_wdt_remove(struct platform_device *pdev)
337{
338	bcm_kona_wdt_debug_exit(pdev);
339	bcm_kona_wdt_shutdown(pdev);
340	watchdog_unregister_device(&bcm_kona_wdt_wdd);
341	dev_dbg(&pdev->dev, "Watchdog driver disabled");
342
343	return 0;
344}
345
346static const struct of_device_id bcm_kona_wdt_of_match[] = {
347	{ .compatible = "brcm,kona-wdt", },
348	{},
349};
350MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
351
352static struct platform_driver bcm_kona_wdt_driver = {
353	.driver = {
354			.name = BCM_KONA_WDT_NAME,
355			.owner = THIS_MODULE,
356			.of_match_table = bcm_kona_wdt_of_match,
357		  },
358	.probe = bcm_kona_wdt_probe,
359	.remove = bcm_kona_wdt_remove,
360	.shutdown = bcm_kona_wdt_shutdown,
361};
362
363module_platform_driver(bcm_kona_wdt_driver);
364
365MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
366MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
367MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
368MODULE_LICENSE("GPL v2");
369