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/reboot.h>
17 #include <linux/init.h>
18 #include <linux/uaccess.h>
19 #include <linux/platform_device.h>
20 #include <linux/clk.h>
21 #include <linux/err.h>
22 #include <linux/io.h>
23 #include <asm/txx9tmr.h>
24
25 #define TIMER_MARGIN 60 /* Default is 60 seconds */
26
27 static int timeout = TIMER_MARGIN; /* in seconds */
28 module_param(timeout, int, 0);
29 MODULE_PARM_DESC(timeout,
30 "Watchdog timeout in seconds. "
31 "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
32 "default=" __MODULE_STRING(TIMER_MARGIN) ")");
33
34 static int nowayout = WATCHDOG_NOWAYOUT;
35 module_param(nowayout, int, 0);
36 MODULE_PARM_DESC(nowayout,
37 "Watchdog cannot be stopped once started "
38 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39
40 #define WD_TIMER_CCD 7 /* 1/256 */
41 #define WD_TIMER_CLK (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
42 #define WD_MAX_TIMEOUT ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
43
44 static unsigned long txx9wdt_alive;
45 static int expect_close;
46 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
47 static struct clk *txx9_imclk;
48
49 static void txx9wdt_ping(void)
50 {
51 __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
52 }
53
54 static void txx9wdt_start(void)
55 {
56 __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
57 __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
58 __raw_writel(0, &txx9wdt_reg->tisr); /* clear pending interrupt */
59 __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
60 &txx9wdt_reg->tcr);
61 __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
62 }
63
64 static void txx9wdt_stop(void)
65 {
66 __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
67 __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
68 &txx9wdt_reg->tcr);
69 }
70
71 static int txx9wdt_open(struct inode *inode, struct file *file)
72 {
73 if (test_and_set_bit(0, &txx9wdt_alive))
74 return -EBUSY;
75
76 if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
77 clear_bit(0, &txx9wdt_alive);
78 return -EBUSY;
79 }
80
81 if (nowayout)
82 __module_get(THIS_MODULE);
83
84 txx9wdt_start();
85 return nonseekable_open(inode, file);
86 }
87
88 static int txx9wdt_release(struct inode *inode, struct file *file)
89 {
90 if (expect_close)
91 txx9wdt_stop();
92 else {
93 printk(KERN_CRIT "txx9wdt: "
94 "Unexpected close, not stopping watchdog!\n");
95 txx9wdt_ping();
96 }
97 clear_bit(0, &txx9wdt_alive);
98 expect_close = 0;
99 return 0;
100 }
101
102 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
103 size_t len, loff_t *ppos)
104 {
105 if (len) {
106 if (!nowayout) {
107 size_t i;
108
109 expect_close = 0;
110 for (i = 0; i != len; i++) {
111 char c;
112 if (get_user(c, data + i))
113 return -EFAULT;
114 if (c == 'V')
115 expect_close = 1;
116 }
117 }
118 txx9wdt_ping();
119 }
120 return len;
121 }
122
123 static int txx9wdt_ioctl(struct inode *inode, struct file *file,
124 unsigned int cmd, unsigned long arg)
125 {
126 void __user *argp = (void __user *)arg;
127 int __user *p = argp;
128 int new_timeout;
129 static struct watchdog_info ident = {
130 .options = WDIOF_SETTIMEOUT |
131 WDIOF_KEEPALIVEPING |
132 WDIOF_MAGICCLOSE,
133 .firmware_version = 0,
134 .identity = "Hardware Watchdog for TXx9",
135 };
136
137 switch (cmd) {
138 default:
139 return -ENOTTY;
140 case WDIOC_GETSUPPORT:
141 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
142 case WDIOC_GETSTATUS:
143 case WDIOC_GETBOOTSTATUS:
144 return put_user(0, p);
145 case WDIOC_KEEPALIVE:
146 txx9wdt_ping();
147 return 0;
148 case WDIOC_SETTIMEOUT:
149 if (get_user(new_timeout, p))
150 return -EFAULT;
151 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
152 return -EINVAL;
153 timeout = new_timeout;
154 txx9wdt_stop();
155 txx9wdt_start();
156 /* Fall */
157 case WDIOC_GETTIMEOUT:
158 return put_user(timeout, p);
159 }
160 }
161
162 static int txx9wdt_notify_sys(struct notifier_block *this, unsigned long code,
163 void *unused)
164 {
165 if (code == SYS_DOWN || code == SYS_HALT)
166 txx9wdt_stop();
167 return NOTIFY_DONE;
168 }
169
170 static const struct file_operations txx9wdt_fops = {
171 .owner = THIS_MODULE,
172 .llseek = no_llseek,
173 .write = txx9wdt_write,
174 .ioctl = txx9wdt_ioctl,
175 .open = txx9wdt_open,
176 .release = txx9wdt_release,
177 };
178
179 static struct miscdevice txx9wdt_miscdev = {
180 .minor = WATCHDOG_MINOR,
181 .name = "watchdog",
182 .fops = &txx9wdt_fops,
183 };
184
185 static struct notifier_block txx9wdt_notifier = {
186 .notifier_call = txx9wdt_notify_sys
187 };
188
189 static int __init txx9wdt_probe(struct platform_device *dev)
190 {
191 struct resource *res;
192 int ret;
193
194 txx9_imclk = clk_get(NULL, "imbus_clk");
195 if (IS_ERR(txx9_imclk)) {
196 ret = PTR_ERR(txx9_imclk);
197 txx9_imclk = NULL;
198 goto exit;
199 }
200 ret = clk_enable(txx9_imclk);
201 if (ret) {
202 clk_put(txx9_imclk);
203 txx9_imclk = NULL;
204 goto exit;
205 }
206
207 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
208 if (!res)
209 goto exit_busy;
210 if (!devm_request_mem_region(&dev->dev,
211 res->start, res->end - res->start + 1,
212 "txx9wdt"))
213 goto exit_busy;
214 txx9wdt_reg = devm_ioremap(&dev->dev,
215 res->start, res->end - res->start + 1);
216 if (!txx9wdt_reg)
217 goto exit_busy;
218
219 ret = register_reboot_notifier(&txx9wdt_notifier);
220 if (ret)
221 goto exit;
222
223 ret = misc_register(&txx9wdt_miscdev);
224 if (ret) {
225 unregister_reboot_notifier(&txx9wdt_notifier);
226 goto exit;
227 }
228
229 printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
230 "timeout=%d sec (max %ld) (nowayout= %d)\n",
231 timeout, WD_MAX_TIMEOUT, nowayout);
232
233 return 0;
234 exit_busy:
235 ret = -EBUSY;
236 exit:
237 if (txx9_imclk) {
238 clk_disable(txx9_imclk);
239 clk_put(txx9_imclk);
240 }
241 return ret;
242 }
243
244 static int __exit txx9wdt_remove(struct platform_device *dev)
245 {
246 misc_deregister(&txx9wdt_miscdev);
247 unregister_reboot_notifier(&txx9wdt_notifier);
248 clk_disable(txx9_imclk);
249 clk_put(txx9_imclk);
250 return 0;
251 }
252
253 static struct platform_driver txx9wdt_driver = {
254 .remove = __exit_p(txx9wdt_remove),
255 .driver = {
256 .name = "txx9wdt",
257 .owner = THIS_MODULE,
258 },
259 };
260
261 static int __init watchdog_init(void)
262 {
263 return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
264 }
265
266 static void __exit watchdog_exit(void)
267 {
268 platform_driver_unregister(&txx9wdt_driver);
269 }
270
271 module_init(watchdog_init);
272 module_exit(watchdog_exit);
273
274 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
275 MODULE_LICENSE("GPL");
276 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
277 MODULE_ALIAS("platform:txx9wdt");
278
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