Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6.git] / drivers / watchdog / txx9wdt.c
1 /*
2  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
3  *
4  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/types.h>
13 #include <linux/miscdevice.h>
14 #include <linux/watchdog.h>
15 #include <linux/fs.h>
16 #include <linux/init.h>
17 #include <linux/uaccess.h>
18 #include <linux/platform_device.h>
19 #include <linux/clk.h>
20 #include <linux/err.h>
21 #include <linux/io.h>
22 #include <asm/txx9tmr.h>
23
24 #define TIMER_MARGIN    60              /* Default is 60 seconds */
25
26 static int timeout = TIMER_MARGIN;      /* in seconds */
27 module_param(timeout, int, 0);
28 MODULE_PARM_DESC(timeout,
29         "Watchdog timeout in seconds. "
30         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
31         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
32
33 static int nowayout = WATCHDOG_NOWAYOUT;
34 module_param(nowayout, int, 0);
35 MODULE_PARM_DESC(nowayout,
36         "Watchdog cannot be stopped once started "
37         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
38
39 #define WD_TIMER_CCD    7       /* 1/256 */
40 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
41 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
42
43 static unsigned long txx9wdt_alive;
44 static int expect_close;
45 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
46 static struct clk *txx9_imclk;
47 static DEFINE_SPINLOCK(txx9_lock);
48
49 static void txx9wdt_ping(void)
50 {
51         spin_lock(&txx9_lock);
52         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
53         spin_unlock(&txx9_lock);
54 }
55
56 static void txx9wdt_start(void)
57 {
58         spin_lock(&txx9_lock);
59         __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
60         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
61         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
62         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
63                      &txx9wdt_reg->tcr);
64         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
65         spin_unlock(&txx9_lock);
66 }
67
68 static void txx9wdt_stop(void)
69 {
70         spin_lock(&txx9_lock);
71         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
72         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
73                      &txx9wdt_reg->tcr);
74         spin_unlock(&txx9_lock);
75 }
76
77 static int txx9wdt_open(struct inode *inode, struct file *file)
78 {
79         if (test_and_set_bit(0, &txx9wdt_alive))
80                 return -EBUSY;
81
82         if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
83                 clear_bit(0, &txx9wdt_alive);
84                 return -EBUSY;
85         }
86
87         if (nowayout)
88                 __module_get(THIS_MODULE);
89
90         txx9wdt_start();
91         return nonseekable_open(inode, file);
92 }
93
94 static int txx9wdt_release(struct inode *inode, struct file *file)
95 {
96         if (expect_close)
97                 txx9wdt_stop();
98         else {
99                 printk(KERN_CRIT "txx9wdt: "
100                        "Unexpected close, not stopping watchdog!\n");
101                 txx9wdt_ping();
102         }
103         clear_bit(0, &txx9wdt_alive);
104         expect_close = 0;
105         return 0;
106 }
107
108 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
109                              size_t len, loff_t *ppos)
110 {
111         if (len) {
112                 if (!nowayout) {
113                         size_t i;
114
115                         expect_close = 0;
116                         for (i = 0; i != len; i++) {
117                                 char c;
118                                 if (get_user(c, data + i))
119                                         return -EFAULT;
120                                 if (c == 'V')
121                                         expect_close = 1;
122                         }
123                 }
124                 txx9wdt_ping();
125         }
126         return len;
127 }
128
129 static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
130                                                         unsigned long arg)
131 {
132         void __user *argp = (void __user *)arg;
133         int __user *p = argp;
134         int new_timeout;
135         static const struct watchdog_info ident = {
136                 .options =              WDIOF_SETTIMEOUT |
137                                         WDIOF_KEEPALIVEPING |
138                                         WDIOF_MAGICCLOSE,
139                 .firmware_version =     0,
140                 .identity =             "Hardware Watchdog for TXx9",
141         };
142
143         switch (cmd) {
144         case WDIOC_GETSUPPORT:
145                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
146         case WDIOC_GETSTATUS:
147         case WDIOC_GETBOOTSTATUS:
148                 return put_user(0, p);
149         case WDIOC_KEEPALIVE:
150                 txx9wdt_ping();
151                 return 0;
152         case WDIOC_SETTIMEOUT:
153                 if (get_user(new_timeout, p))
154                         return -EFAULT;
155                 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
156                         return -EINVAL;
157                 timeout = new_timeout;
158                 txx9wdt_stop();
159                 txx9wdt_start();
160                 /* Fall */
161         case WDIOC_GETTIMEOUT:
162                 return put_user(timeout, p);
163         default:
164                 return -ENOTTY;
165         }
166 }
167
168 static const struct file_operations txx9wdt_fops = {
169         .owner          =       THIS_MODULE,
170         .llseek         =       no_llseek,
171         .write          =       txx9wdt_write,
172         .unlocked_ioctl =       txx9wdt_ioctl,
173         .open           =       txx9wdt_open,
174         .release        =       txx9wdt_release,
175 };
176
177 static struct miscdevice txx9wdt_miscdev = {
178         .minor  =       WATCHDOG_MINOR,
179         .name   =       "watchdog",
180         .fops   =       &txx9wdt_fops,
181 };
182
183 static int __init txx9wdt_probe(struct platform_device *dev)
184 {
185         struct resource *res;
186         int ret;
187
188         txx9_imclk = clk_get(NULL, "imbus_clk");
189         if (IS_ERR(txx9_imclk)) {
190                 ret = PTR_ERR(txx9_imclk);
191                 txx9_imclk = NULL;
192                 goto exit;
193         }
194         ret = clk_enable(txx9_imclk);
195         if (ret) {
196                 clk_put(txx9_imclk);
197                 txx9_imclk = NULL;
198                 goto exit;
199         }
200
201         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
202         if (!res)
203                 goto exit_busy;
204         if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),
205                                      "txx9wdt"))
206                 goto exit_busy;
207         txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));
208         if (!txx9wdt_reg)
209                 goto exit_busy;
210
211         ret = misc_register(&txx9wdt_miscdev);
212         if (ret) {
213                 goto exit;
214         }
215
216         printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
217                "timeout=%d sec (max %ld) (nowayout= %d)\n",
218                timeout, WD_MAX_TIMEOUT, nowayout);
219
220         return 0;
221 exit_busy:
222         ret = -EBUSY;
223 exit:
224         if (txx9_imclk) {
225                 clk_disable(txx9_imclk);
226                 clk_put(txx9_imclk);
227         }
228         return ret;
229 }
230
231 static int __exit txx9wdt_remove(struct platform_device *dev)
232 {
233         misc_deregister(&txx9wdt_miscdev);
234         clk_disable(txx9_imclk);
235         clk_put(txx9_imclk);
236         return 0;
237 }
238
239 static void txx9wdt_shutdown(struct platform_device *dev)
240 {
241         txx9wdt_stop();
242 }
243
244 static struct platform_driver txx9wdt_driver = {
245         .remove = __exit_p(txx9wdt_remove),
246         .shutdown = txx9wdt_shutdown,
247         .driver = {
248                 .name = "txx9wdt",
249                 .owner = THIS_MODULE,
250         },
251 };
252
253 static int __init watchdog_init(void)
254 {
255         return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
256 }
257
258 static void __exit watchdog_exit(void)
259 {
260         platform_driver_unregister(&txx9wdt_driver);
261 }
262
263 module_init(watchdog_init);
264 module_exit(watchdog_exit);
265
266 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
267 MODULE_LICENSE("GPL");
268 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
269 MODULE_ALIAS("platform:txx9wdt");