1 /*
2 * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
3 *
4 * Author: James Chapman <jchapman@katalix.com>
5 *
6 * Platform-specific setup code should configure the dog to generate
7 * interrupt or reset as required. This code only enables/disables
8 * and services the watchdog.
9 *
10 * Derived from mpc8xx_wdt.c, with the following copyright.
11 *
12 * 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under
13 * the terms of the GNU General Public License version 2. This program
14 * is licensed "as is" without any warranty of any kind, whether express
15 * or implied.
16 */
17
18 #include <linux/fs.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/miscdevice.h>
22 #include <linux/module.h>
23 #include <linux/watchdog.h>
24 #include <linux/platform_device.h>
25
26 #include <linux/mv643xx.h>
27 #include <asm/uaccess.h>
28 #include <asm/io.h>
29
30 #define MV64x60_WDT_WDC_OFFSET 0
31
32 /*
33 * The watchdog configuration register contains a pair of 2-bit fields,
34 * 1. a reload field, bits 27-26, which triggers a reload of
35 * the countdown register, and
36 * 2. an enable field, bits 25-24, which toggles between
37 * enabling and disabling the watchdog timer.
38 * Bit 31 is a read-only field which indicates whether the
39 * watchdog timer is currently enabled.
40 *
41 * The low 24 bits contain the timer reload value.
42 */
43 #define MV64x60_WDC_ENABLE_SHIFT 24
44 #define MV64x60_WDC_SERVICE_SHIFT 26
45 #define MV64x60_WDC_ENABLED_SHIFT 31
46
47 #define MV64x60_WDC_ENABLED_TRUE 1
48 #define MV64x60_WDC_ENABLED_FALSE 0
49
50 /* Flags bits */
51 #define MV64x60_WDOG_FLAG_OPENED 0
52
53 static unsigned long wdt_flags;
54 static int wdt_status;
55 static void __iomem *mv64x60_wdt_regs;
56 static int mv64x60_wdt_timeout;
57 static int mv64x60_wdt_count;
58 static unsigned int bus_clk;
59 static char expect_close;
60 static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
61
62 static int nowayout = WATCHDOG_NOWAYOUT;
63 module_param(nowayout, int, 0);
64 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
65
66 static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
67 {
68 u32 data;
69 u32 enabled;
70 int ret = 0;
71
72 spin_lock(&mv64x60_wdt_spinlock);
73 data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
74 enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
75
76 /* only toggle the requested field if enabled state matches predicate */
77 if ((enabled ^ enabled_predicate) == 0) {
78 /* We write a 1, then a 2 -- to the appropriate field */
79 data = (1 << field_shift) | mv64x60_wdt_count;
80 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
81
82 data = (2 << field_shift) | mv64x60_wdt_count;
83 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
84 ret = 1;
85 }
86 spin_unlock(&mv64x60_wdt_spinlock);
87
88 return ret;
89 }
90
91 static void mv64x60_wdt_service(void)
92 {
93 mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
94 MV64x60_WDC_SERVICE_SHIFT);
95 }
96
97 static void mv64x60_wdt_handler_enable(void)
98 {
99 if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
100 MV64x60_WDC_ENABLE_SHIFT)) {
101 mv64x60_wdt_service();
102 printk(KERN_NOTICE "mv64x60_wdt: watchdog activated\n");
103 }
104 }
105
106 static void mv64x60_wdt_handler_disable(void)
107 {
108 if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
109 MV64x60_WDC_ENABLE_SHIFT))
110 printk(KERN_NOTICE "mv64x60_wdt: watchdog deactivated\n");
111 }
112
113 static void mv64x60_wdt_set_timeout(unsigned int timeout)
114 {
115 /* maximum bus cycle count is 0xFFFFFFFF */
116 if (timeout > 0xFFFFFFFF / bus_clk)
117 timeout = 0xFFFFFFFF / bus_clk;
118
119 mv64x60_wdt_count = timeout * bus_clk >> 8;
120 mv64x60_wdt_timeout = timeout;
121 }
122
123 static int mv64x60_wdt_open(struct inode *inode, struct file *file)
124 {
125 if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
126 return -EBUSY;
127
128 if (nowayout)
129 __module_get(THIS_MODULE);
130
131 mv64x60_wdt_handler_enable();
132
133 return nonseekable_open(inode, file);
134 }
135
136 static int mv64x60_wdt_release(struct inode *inode, struct file *file)
137 {
138 if (expect_close == 42)
139 mv64x60_wdt_handler_disable();
140 else {
141 printk(KERN_CRIT
142 "mv64x60_wdt: unexpected close, not stopping timer!\n");
143 mv64x60_wdt_service();
144 }
145 expect_close = 0;
146
147 clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
148
149 return 0;
150 }
151
152 static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
153 size_t len, loff_t * ppos)
154 {
155 if (len) {
156 if (!nowayout) {
157 size_t i;
158
159 expect_close = 0;
160
161 for (i = 0; i != len; i++) {
162 char c;
163 if(get_user(c, data + i))
164 return -EFAULT;
165 if (c == 'V')
166 expect_close = 42;
167 }
168 }
169 mv64x60_wdt_service();
170 }
171
172 return len;
173 }
174
175 static int mv64x60_wdt_ioctl(struct inode *inode, struct file *file,
176 unsigned int cmd, unsigned long arg)
177 {
178 int timeout;
179 int options;
180 void __user *argp = (void __user *)arg;
181 static struct watchdog_info info = {
182 .options = WDIOF_SETTIMEOUT |
183 WDIOF_MAGICCLOSE |
184 WDIOF_KEEPALIVEPING,
185 .firmware_version = 0,
186 .identity = "MV64x60 watchdog",
187 };
188
189 switch (cmd) {
190 case WDIOC_GETSUPPORT:
191 if (copy_to_user(argp, &info, sizeof(info)))
192 return -EFAULT;
193 break;
194
195 case WDIOC_GETSTATUS:
196 case WDIOC_GETBOOTSTATUS:
197 if (put_user(wdt_status, (int __user *)argp))
198 return -EFAULT;
199 wdt_status &= ~WDIOF_KEEPALIVEPING;
200 break;
201
202 case WDIOC_GETTEMP:
203 return -EOPNOTSUPP;
204
205 case WDIOC_SETOPTIONS:
206 if (get_user(options, (int __user *)argp))
207 return -EFAULT;
208
209 if (options & WDIOS_DISABLECARD)
210 mv64x60_wdt_handler_disable();
211
212 if (options & WDIOS_ENABLECARD)
213 mv64x60_wdt_handler_enable();
214 break;
215
216 case WDIOC_KEEPALIVE:
217 mv64x60_wdt_service();
218 wdt_status |= WDIOF_KEEPALIVEPING;
219 break;
220
221 case WDIOC_SETTIMEOUT:
222 if (get_user(timeout, (int __user *)argp))
223 return -EFAULT;
224 mv64x60_wdt_set_timeout(timeout);
225 /* Fall through */
226
227 case WDIOC_GETTIMEOUT:
228 if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
229 return -EFAULT;
230 break;
231
232 default:
233 return -ENOTTY;
234 }
235
236 return 0;
237 }
238
239 static const struct file_operations mv64x60_wdt_fops = {
240 .owner = THIS_MODULE,
241 .llseek = no_llseek,
242 .write = mv64x60_wdt_write,
243 .ioctl = mv64x60_wdt_ioctl,
244 .open = mv64x60_wdt_open,
245 .release = mv64x60_wdt_release,
246 };
247
248 static struct miscdevice mv64x60_wdt_miscdev = {
249 .minor = WATCHDOG_MINOR,
250 .name = "watchdog",
251 .fops = &mv64x60_wdt_fops,
252 };
253
254 static int __devinit mv64x60_wdt_probe(struct platform_device *dev)
255 {
256 struct mv64x60_wdt_pdata *pdata = dev->dev.platform_data;
257 struct resource *r;
258 int timeout = 10;
259
260 bus_clk = 133; /* in MHz */
261 if (pdata) {
262 timeout = pdata->timeout;
263 bus_clk = pdata->bus_clk;
264 }
265
266 /* Since bus_clk is truncated MHz, actual frequency could be
267 * up to 1MHz higher. Round up, since it's better to time out
268 * too late than too soon.
269 */
270 bus_clk++;
271 bus_clk *= 1000000; /* convert to Hz */
272
273 r = platform_get_resource(dev, IORESOURCE_MEM, 0);
274 if (!r)
275 return -ENODEV;
276
277 mv64x60_wdt_regs = ioremap(r->start, r->end - r->start + 1);
278 if (mv64x60_wdt_regs == NULL)
279 return -ENOMEM;
280
281 mv64x60_wdt_set_timeout(timeout);
282
283 mv64x60_wdt_handler_disable(); /* in case timer was already running */
284
285 return misc_register(&mv64x60_wdt_miscdev);
286 }
287
288 static int __devexit mv64x60_wdt_remove(struct platform_device *dev)
289 {
290 misc_deregister(&mv64x60_wdt_miscdev);
291
292 mv64x60_wdt_handler_disable();
293
294 iounmap(mv64x60_wdt_regs);
295
296 return 0;
297 }
298
299 static struct platform_driver mv64x60_wdt_driver = {
300 .probe = mv64x60_wdt_probe,
301 .remove = __devexit_p(mv64x60_wdt_remove),
302 .driver = {
303 .owner = THIS_MODULE,
304 .name = MV64x60_WDT_NAME,
305 },
306 };
307
308 static int __init mv64x60_wdt_init(void)
309 {
310 printk(KERN_INFO "MV64x60 watchdog driver\n");
311
312 return platform_driver_register(&mv64x60_wdt_driver);
313 }
314
315 static void __exit mv64x60_wdt_exit(void)
316 {
317 platform_driver_unregister(&mv64x60_wdt_driver);
318 }
319
320 module_init(mv64x60_wdt_init);
321 module_exit(mv64x60_wdt_exit);
322
323 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
324 MODULE_DESCRIPTION("MV64x60 watchdog driver");
325 MODULE_LICENSE("GPL");
326 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
327 MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
328
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