1/*
2 *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
3 *  JZ4740 Watchdog driver
4 *
5 *  This program is free software; you can redistribute it and/or modify it
6 *  under  the terms of the GNU General  Public License as published by the
7 *  Free Software Foundation;  either version 2 of the License, or (at your
8 *  option) any later version.
9 *
10 *  You should have received a copy of the GNU General Public License along
11 *  with this program; if not, write to the Free Software Foundation, Inc.,
12 *  675 Mass Ave, Cambridge, MA 02139, USA.
13 *
14 */
15
16#include <linux/module.h>
17#include <linux/moduleparam.h>
18#include <linux/types.h>
19#include <linux/kernel.h>
20#include <linux/fs.h>
21#include <linux/miscdevice.h>
22#include <linux/watchdog.h>
23#include <linux/init.h>
24#include <linux/bitops.h>
25#include <linux/platform_device.h>
26#include <linux/spinlock.h>
27#include <linux/uaccess.h>
28#include <linux/io.h>
29#include <linux/device.h>
30#include <linux/clk.h>
31#include <linux/slab.h>
32
33#include <asm/mach-jz4740/timer.h>
34
35#define JZ_REG_WDT_TIMER_DATA     0x0
36#define JZ_REG_WDT_COUNTER_ENABLE 0x4
37#define JZ_REG_WDT_TIMER_COUNTER  0x8
38#define JZ_REG_WDT_TIMER_CONTROL  0xC
39
40#define JZ_WDT_CLOCK_PCLK 0x1
41#define JZ_WDT_CLOCK_RTC  0x2
42#define JZ_WDT_CLOCK_EXT  0x4
43
44#define WDT_IN_USE        0
45#define WDT_OK_TO_CLOSE   1
46
47#define JZ_WDT_CLOCK_DIV_SHIFT   3
48
49#define JZ_WDT_CLOCK_DIV_1    (0 << JZ_WDT_CLOCK_DIV_SHIFT)
50#define JZ_WDT_CLOCK_DIV_4    (1 << JZ_WDT_CLOCK_DIV_SHIFT)
51#define JZ_WDT_CLOCK_DIV_16   (2 << JZ_WDT_CLOCK_DIV_SHIFT)
52#define JZ_WDT_CLOCK_DIV_64   (3 << JZ_WDT_CLOCK_DIV_SHIFT)
53#define JZ_WDT_CLOCK_DIV_256  (4 << JZ_WDT_CLOCK_DIV_SHIFT)
54#define JZ_WDT_CLOCK_DIV_1024 (5 << JZ_WDT_CLOCK_DIV_SHIFT)
55
56#define DEFAULT_HEARTBEAT 5
57#define MAX_HEARTBEAT     2048
58
59static struct {
60	void __iomem *base;
61	struct resource	*mem;
62	struct clk *rtc_clk;
63	unsigned long status;
64} jz4740_wdt;
65
66static int heartbeat = DEFAULT_HEARTBEAT;
67
68
69static void jz4740_wdt_service(void)
70{
71	writew(0x0, jz4740_wdt.base + JZ_REG_WDT_TIMER_COUNTER);
72}
73
74static void jz4740_wdt_set_heartbeat(int new_heartbeat)
75{
76	unsigned int rtc_clk_rate;
77	unsigned int timeout_value;
78	unsigned short clock_div = JZ_WDT_CLOCK_DIV_1;
79
80	heartbeat = new_heartbeat;
81
82	rtc_clk_rate = clk_get_rate(jz4740_wdt.rtc_clk);
83
84	timeout_value = rtc_clk_rate * heartbeat;
85	while (timeout_value > 0xffff) {
86		if (clock_div == JZ_WDT_CLOCK_DIV_1024) {
87			/* Requested timeout too high;
88			* use highest possible value. */
89			timeout_value = 0xffff;
90			break;
91		}
92		timeout_value >>= 2;
93		clock_div += (1 << JZ_WDT_CLOCK_DIV_SHIFT);
94	}
95
96	writeb(0x0, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
97	writew(clock_div, jz4740_wdt.base + JZ_REG_WDT_TIMER_CONTROL);
98
99	writew((u16)timeout_value, jz4740_wdt.base + JZ_REG_WDT_TIMER_DATA);
100	writew(0x0, jz4740_wdt.base + JZ_REG_WDT_TIMER_COUNTER);
101	writew(clock_div | JZ_WDT_CLOCK_RTC,
102		jz4740_wdt.base + JZ_REG_WDT_TIMER_CONTROL);
103
104	writeb(0x1, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
105}
106
107static void jz4740_wdt_enable(void)
108{
109	jz4740_timer_enable_watchdog();
110	jz4740_wdt_set_heartbeat(heartbeat);
111}
112
113static void jz4740_wdt_disable(void)
114{
115	jz4740_timer_disable_watchdog();
116	writeb(0x0, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
117}
118
119static int jz4740_wdt_open(struct inode *inode, struct file *file)
120{
121	if (test_and_set_bit(WDT_IN_USE, &jz4740_wdt.status))
122		return -EBUSY;
123
124	jz4740_wdt_enable();
125
126	return nonseekable_open(inode, file);
127}
128
129static ssize_t jz4740_wdt_write(struct file *file, const char *data,
130		size_t len, loff_t *ppos)
131{
132	if (len) {
133		size_t i;
134
135		clear_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status);
136		for (i = 0; i != len; i++) {
137			char c;
138
139			if (get_user(c, data + i))
140				return -EFAULT;
141
142			if (c == 'V')
143				set_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status);
144		}
145		jz4740_wdt_service();
146	}
147
148	return len;
149}
150
151static const struct watchdog_info ident = {
152	.options = WDIOF_KEEPALIVEPING,
153	.identity = "jz4740 Watchdog",
154};
155
156static long jz4740_wdt_ioctl(struct file *file,
157					unsigned int cmd, unsigned long arg)
158{
159	int ret = -ENOTTY;
160	int heartbeat_seconds;
161
162	switch (cmd) {
163	case WDIOC_GETSUPPORT:
164		ret = copy_to_user((struct watchdog_info *)arg, &ident,
165				sizeof(ident)) ? -EFAULT : 0;
166		break;
167
168	case WDIOC_GETSTATUS:
169	case WDIOC_GETBOOTSTATUS:
170		ret = put_user(0, (int *)arg);
171		break;
172
173	case WDIOC_KEEPALIVE:
174		jz4740_wdt_service();
175		return 0;
176
177	case WDIOC_SETTIMEOUT:
178		if (get_user(heartbeat_seconds, (int __user *)arg))
179			return -EFAULT;
180
181		jz4740_wdt_set_heartbeat(heartbeat_seconds);
182		return 0;
183
184	case WDIOC_GETTIMEOUT:
185		return put_user(heartbeat, (int *)arg);
186
187	default:
188		break;
189	}
190
191	return ret;
192}
193
194static int jz4740_wdt_release(struct inode *inode, struct file *file)
195{
196	jz4740_wdt_service();
197
198	if (test_and_clear_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status))
199		jz4740_wdt_disable();
200
201	clear_bit(WDT_IN_USE, &jz4740_wdt.status);
202	return 0;
203}
204
205static const struct file_operations jz4740_wdt_fops = {
206	.owner = THIS_MODULE,
207	.llseek = no_llseek,
208	.write = jz4740_wdt_write,
209	.unlocked_ioctl = jz4740_wdt_ioctl,
210	.open = jz4740_wdt_open,
211	.release = jz4740_wdt_release,
212};
213
214static struct miscdevice jz4740_wdt_miscdev = {
215	.minor = WATCHDOG_MINOR,
216	.name = "watchdog",
217	.fops = &jz4740_wdt_fops,
218};
219
220static int __devinit jz4740_wdt_probe(struct platform_device *pdev)
221{
222	int ret = 0, size;
223	struct resource *res;
224	struct device *dev = &pdev->dev;
225
226	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
227	if (res == NULL) {
228		dev_err(dev, "failed to get memory region resource\n");
229		return -ENXIO;
230	}
231
232	size = resource_size(res);
233	jz4740_wdt.mem = request_mem_region(res->start, size, pdev->name);
234	if (jz4740_wdt.mem == NULL) {
235		dev_err(dev, "failed to get memory region\n");
236		return -EBUSY;
237	}
238
239	jz4740_wdt.base = ioremap_nocache(res->start, size);
240	if (jz4740_wdt.base == NULL) {
241		dev_err(dev, "failed to map memory region\n");
242		ret = -EBUSY;
243		goto err_release_region;
244	}
245
246	jz4740_wdt.rtc_clk = clk_get(NULL, "rtc");
247	if (IS_ERR(jz4740_wdt.rtc_clk)) {
248		dev_err(dev, "cannot find RTC clock\n");
249		ret = PTR_ERR(jz4740_wdt.rtc_clk);
250		goto err_iounmap;
251	}
252
253	ret = misc_register(&jz4740_wdt_miscdev);
254	if (ret < 0) {
255		dev_err(dev, "cannot register misc device\n");
256		goto err_disable_clk;
257	}
258
259	return 0;
260
261err_disable_clk:
262	clk_put(jz4740_wdt.rtc_clk);
263err_iounmap:
264	iounmap(jz4740_wdt.base);
265err_release_region:
266	release_mem_region(jz4740_wdt.mem->start,
267			resource_size(jz4740_wdt.mem));
268	return ret;
269}
270
271
272static int __devexit jz4740_wdt_remove(struct platform_device *pdev)
273{
274	jz4740_wdt_disable();
275	misc_deregister(&jz4740_wdt_miscdev);
276	clk_put(jz4740_wdt.rtc_clk);
277
278	iounmap(jz4740_wdt.base);
279	jz4740_wdt.base = NULL;
280
281	release_mem_region(jz4740_wdt.mem->start,
282				resource_size(jz4740_wdt.mem));
283	jz4740_wdt.mem = NULL;
284
285	return 0;
286}
287
288
289static struct platform_driver jz4740_wdt_driver = {
290	.probe = jz4740_wdt_probe,
291	.remove = __devexit_p(jz4740_wdt_remove),
292	.driver = {
293		.name = "jz4740-wdt",
294		.owner	= THIS_MODULE,
295	},
296};
297
298module_platform_driver(jz4740_wdt_driver);
299
300MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
301MODULE_DESCRIPTION("jz4740 Watchdog Driver");
302
303module_param(heartbeat, int, 0);
304MODULE_PARM_DESC(heartbeat,
305		"Watchdog heartbeat period in seconds from 1 to "
306		__MODULE_STRING(MAX_HEARTBEAT) ", default "
307		__MODULE_STRING(DEFAULT_HEARTBEAT));
308
309MODULE_LICENSE("GPL");
310MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
311MODULE_ALIAS("platform:jz4740-wdt");
312