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 #include <linux/mv643xx.h>
26 #include <linux/uaccess.h>
27 #include <linux/io.h>
28
29 #define MV64x60_WDT_WDC_OFFSET 0
30
31 /*
32 * The watchdog configuration register contains a pair of 2-bit fields,
33 * 1. a reload field, bits 27-26, which triggers a reload of
34 * the countdown register, and
35 * 2. an enable field, bits 25-24, which toggles between
36 * enabling and disabling the watchdog timer.
37 * Bit 31 is a read-only field which indicates whether the
38 * watchdog timer is currently enabled.
39 *
40 * The low 24 bits contain the timer reload value.
41 */
42 #define MV64x60_WDC_ENABLE_SHIFT 24
43 #define MV64x60_WDC_SERVICE_SHIFT 26
44 #define MV64x60_WDC_ENABLED_SHIFT 31
45
46 #define MV64x60_WDC_ENABLED_TRUE 1
47 #define MV64x60_WDC_ENABLED_FALSE 0
48
49 /* Flags bits */
50 #define MV64x60_WDOG_FLAG_OPENED 0
51
52 static unsigned long wdt_flags;
53 static int wdt_status;
54 static void __iomem *mv64x60_wdt_regs;
55 static int mv64x60_wdt_timeout;
56 static int mv64x60_wdt_count;
57 static unsigned int bus_clk;
58 static char expect_close;
59 static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
60
61 static int nowayout = WATCHDOG_NOWAYOUT;
62 module_param(nowayout, int, 0);
63 MODULE_PARM_DESC(nowayout,
64 "Watchdog cannot be stopped once started (default="
65 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
66
67 static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
68 {
69 u32 data;
70 u32 enabled;
71 int ret = 0;
72
73 spin_lock(&mv64x60_wdt_spinlock);
74 data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
75 enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
76
77 /* only toggle the requested field if enabled state matches predicate */
78 if ((enabled ^ enabled_predicate) == 0) {
79 /* We write a 1, then a 2 -- to the appropriate field */
80 data = (1 << field_shift) | mv64x60_wdt_count;
81 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
82
83 data = (2 << field_shift) | mv64x60_wdt_count;
84 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
85 ret = 1;
86 }
87 spin_unlock(&mv64x60_wdt_spinlock);
88
89 return ret;
90 }
91
92 static void mv64x60_wdt_service(void)
93 {
94 mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
95 MV64x60_WDC_SERVICE_SHIFT);
96 }
97
98 static void mv64x60_wdt_handler_enable(void)
99 {
100 if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
101 MV64x60_WDC_ENABLE_SHIFT)) {
102 mv64x60_wdt_service();
103 printk(KERN_NOTICE "mv64x60_wdt: watchdog activated\n");
104 }
105 }
106
107 static void mv64x60_wdt_handler_disable(void)
108 {
109 if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
110 MV64x60_WDC_ENABLE_SHIFT))
111 printk(KERN_NOTICE "mv64x60_wdt: watchdog deactivated\n");
112 }
113
114 static void mv64x60_wdt_set_timeout(unsigned int timeout)
115 {
116 /* maximum bus cycle count is 0xFFFFFFFF */
117 if (timeout > 0xFFFFFFFF / bus_clk)
118 timeout = 0xFFFFFFFF / bus_clk;
119
120 mv64x60_wdt_count = timeout * bus_clk >> 8;
121 mv64x60_wdt_timeout = timeout;
122 }
123
124 static int mv64x60_wdt_open(struct inode *inode, struct file *file)
125 {
126 if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
127 return -EBUSY;
128
129 if (nowayout)
130 __module_get(THIS_MODULE);
131
132 mv64x60_wdt_handler_enable();
133
134 return nonseekable_open(inode, file);
135 }
136
137 static int mv64x60_wdt_release(struct inode *inode, struct file *file)
138 {
139 if (expect_close == 42)
140 mv64x60_wdt_handler_disable();
141 else {
142 printk(KERN_CRIT
143 "mv64x60_wdt: unexpected close, not stopping timer!\n");
144 mv64x60_wdt_service();
145 }
146 expect_close = 0;
147
148 clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
149
150 return 0;
151 }
152
153 static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
154 size_t len, loff_t *ppos)
155 {
156 if (len) {
157 if (!nowayout) {
158 size_t i;
159
160 expect_close = 0;
161
162 for (i = 0; i != len; i++) {
163 char c;
164 if (get_user(c, data + i))
165 return -EFAULT;
166 if (c == 'V')
167 expect_close = 42;
168 }
169 }
170 mv64x60_wdt_service();
171 }
172
173 return len;
174 }
175
176 static long mv64x60_wdt_ioctl(struct file *file,
177 unsigned int cmd, unsigned long arg)
178 {
179 int timeout;
180 int options;
181 void __user *argp = (void __user *)arg;
182 static struct watchdog_info info = {
183 .options = WDIOF_SETTIMEOUT |
184 WDIOF_MAGICCLOSE |
185 WDIOF_KEEPALIVEPING,
186 .firmware_version = 0,
187 .identity = "MV64x60 watchdog",
188 };
189
190 switch (cmd) {
191 case WDIOC_GETSUPPORT:
192 if (copy_to_user(argp, &info, sizeof(info)))
193 return -EFAULT;
194 break;
195
196 case WDIOC_GETSTATUS:
197 case WDIOC_GETBOOTSTATUS:
198 if (put_user(wdt_status, (int __user *)argp))
199 return -EFAULT;
200 wdt_status &= ~WDIOF_KEEPALIVEPING;
201 break;
202
203 case WDIOC_GETTEMP:
204 return -EOPNOTSUPP;
205
206 case WDIOC_SETOPTIONS:
207 if (get_user(options, (int __user *)argp))
208 return -EFAULT;
209
210 if (options & WDIOS_DISABLECARD)
211 mv64x60_wdt_handler_disable();
212
213 if (options & WDIOS_ENABLECARD)
214 mv64x60_wdt_handler_enable();
215 break;
216
217 case WDIOC_KEEPALIVE:
218 mv64x60_wdt_service();
219 wdt_status |= WDIOF_KEEPALIVEPING;
220 break;
221
222 case WDIOC_SETTIMEOUT:
223 if (get_user(timeout, (int __user *)argp))
224 return -EFAULT;
225 mv64x60_wdt_set_timeout(timeout);
226 /* Fall through */
227
228 case WDIOC_GETTIMEOUT:
229 if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
230 return -EFAULT;
231 break;
232
233 default:
234 return -ENOTTY;
235 }
236
237 return 0;
238 }
239
240 static const struct file_operations mv64x60_wdt_fops = {
241 .owner = THIS_MODULE,
242 .llseek = no_llseek,
243 .write = mv64x60_wdt_write,
244 .unlocked_ioctl = mv64x60_wdt_ioctl,
245 .open = mv64x60_wdt_open,
246 .release = mv64x60_wdt_release,
247 };
248
249 static struct miscdevice mv64x60_wdt_miscdev = {
250 .minor = WATCHDOG_MINOR,
251 .name = "watchdog",
252 .fops = &mv64x60_wdt_fops,
253 };
254
255 static int __devinit mv64x60_wdt_probe(struct platform_device *dev)
256 {
257 struct mv64x60_wdt_pdata *pdata = dev->dev.platform_data;
258 struct resource *r;
259 int timeout = 10;
260
261 bus_clk = 133; /* in MHz */
262 if (pdata) {
263 timeout = pdata->timeout;
264 bus_clk = pdata->bus_clk;
265 }
266
267 /* Since bus_clk is truncated MHz, actual frequency could be
268 * up to 1MHz higher. Round up, since it's better to time out
269 * too late than too soon.
270 */
271 bus_clk++;
272 bus_clk *= 1000000; /* convert to Hz */
273
274 r = platform_get_resource(dev, IORESOURCE_MEM, 0);
275 if (!r)
276 return -ENODEV;
277
278 mv64x60_wdt_regs = ioremap(r->start, r->end - r->start + 1);
279 if (mv64x60_wdt_regs == NULL)
280 return -ENOMEM;
281
282 mv64x60_wdt_set_timeout(timeout);
283
284 mv64x60_wdt_handler_disable(); /* in case timer was already running */
285
286 return misc_register(&mv64x60_wdt_miscdev);
287 }
288
289 static int __devexit mv64x60_wdt_remove(struct platform_device *dev)
290 {
291 misc_deregister(&mv64x60_wdt_miscdev);
292
293 mv64x60_wdt_handler_disable();
294
295 iounmap(mv64x60_wdt_regs);
296
297 return 0;
298 }
299
300 static struct platform_driver mv64x60_wdt_driver = {
301 .probe = mv64x60_wdt_probe,
302 .remove = __devexit_p(mv64x60_wdt_remove),
303 .driver = {
304 .owner = THIS_MODULE,
305 .name = MV64x60_WDT_NAME,
306 },
307 };
308
309 static int __init mv64x60_wdt_init(void)
310 {
311 printk(KERN_INFO "MV64x60 watchdog driver\n");
312
313 return platform_driver_register(&mv64x60_wdt_driver);
314 }
315
316 static void __exit mv64x60_wdt_exit(void)
317 {
318 platform_driver_unregister(&mv64x60_wdt_driver);
319 }
320
321 module_init(mv64x60_wdt_init);
322 module_exit(mv64x60_wdt_exit);
323
324 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
325 MODULE_DESCRIPTION("MV64x60 watchdog driver");
326 MODULE_LICENSE("GPL");
327 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
328 MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
329
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