1 /*
2 * Copyright (c) 2009 Nuvoton technology corporation.
3 *
4 * Wan ZongShun <mcuos.com@gmail.com>
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 as published by
8 * the Free Software Foundation;version 2 of the License.
9 *
10 */
11
12 #include <linux/bitops.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/io.h>
16 #include <linux/clk.h>
17 #include <linux/kernel.h>
18 #include <linux/miscdevice.h>
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/platform_device.h>
22 #include <linux/slab.h>
23 #include <linux/interrupt.h>
24 #include <linux/types.h>
25 #include <linux/watchdog.h>
26 #include <linux/uaccess.h>
27
28 #define REG_WTCR 0x1c
29 #define WTCLK (0x01 << 10)
30 #define WTE (0x01 << 7) /*wdt enable*/
31 #define WTIS (0x03 << 4)
32 #define WTIF (0x01 << 3)
33 #define WTRF (0x01 << 2)
34 #define WTRE (0x01 << 1)
35 #define WTR (0x01 << 0)
36 /*
37 * The watchdog time interval can be calculated via following formula:
38 * WTIS real time interval (formula)
39 * 0x00 ((2^ 14 ) * ((external crystal freq) / 256))seconds
40 * 0x01 ((2^ 16 ) * ((external crystal freq) / 256))seconds
41 * 0x02 ((2^ 18 ) * ((external crystal freq) / 256))seconds
42 * 0x03 ((2^ 20 ) * ((external crystal freq) / 256))seconds
43 *
44 * The external crystal freq is 15Mhz in the nuc900 evaluation board.
45 * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
46 * 0x03 = +- 16.92 seconds..
47 */
48 #define WDT_HW_TIMEOUT 0x02
49 #define WDT_TIMEOUT (HZ/2)
50 #define WDT_HEARTBEAT 15
51
52 static int heartbeat = WDT_HEARTBEAT;
53 module_param(heartbeat, int, 0);
54 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
55 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
56
57 static bool nowayout = WATCHDOG_NOWAYOUT;
58 module_param(nowayout, bool, 0);
59 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
60 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
61
62 struct nuc900_wdt {
63 struct clk *wdt_clock;
64 struct platform_device *pdev;
65 void __iomem *wdt_base;
66 char expect_close;
67 struct timer_list timer;
68 spinlock_t wdt_lock;
69 unsigned long next_heartbeat;
70 };
71
72 static unsigned long nuc900wdt_busy;
73 static struct nuc900_wdt *nuc900_wdt;
74
nuc900_wdt_keepalive(void)75 static inline void nuc900_wdt_keepalive(void)
76 {
77 unsigned int val;
78
79 spin_lock(&nuc900_wdt->wdt_lock);
80
81 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
82 val |= (WTR | WTIF);
83 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
84
85 spin_unlock(&nuc900_wdt->wdt_lock);
86 }
87
nuc900_wdt_start(void)88 static inline void nuc900_wdt_start(void)
89 {
90 unsigned int val;
91
92 spin_lock(&nuc900_wdt->wdt_lock);
93
94 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
95 val |= (WTRE | WTE | WTR | WTCLK | WTIF);
96 val &= ~WTIS;
97 val |= (WDT_HW_TIMEOUT << 0x04);
98 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
99
100 spin_unlock(&nuc900_wdt->wdt_lock);
101
102 nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
103 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
104 }
105
nuc900_wdt_stop(void)106 static inline void nuc900_wdt_stop(void)
107 {
108 unsigned int val;
109
110 del_timer(&nuc900_wdt->timer);
111
112 spin_lock(&nuc900_wdt->wdt_lock);
113
114 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
115 val &= ~WTE;
116 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
117
118 spin_unlock(&nuc900_wdt->wdt_lock);
119 }
120
nuc900_wdt_ping(void)121 static inline void nuc900_wdt_ping(void)
122 {
123 nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
124 }
125
nuc900_wdt_open(struct inode * inode,struct file * file)126 static int nuc900_wdt_open(struct inode *inode, struct file *file)
127 {
128
129 if (test_and_set_bit(0, &nuc900wdt_busy))
130 return -EBUSY;
131
132 nuc900_wdt_start();
133
134 return nonseekable_open(inode, file);
135 }
136
nuc900_wdt_close(struct inode * inode,struct file * file)137 static int nuc900_wdt_close(struct inode *inode, struct file *file)
138 {
139 if (nuc900_wdt->expect_close == 42)
140 nuc900_wdt_stop();
141 else {
142 dev_crit(&nuc900_wdt->pdev->dev,
143 "Unexpected close, not stopping watchdog!\n");
144 nuc900_wdt_ping();
145 }
146
147 nuc900_wdt->expect_close = 0;
148 clear_bit(0, &nuc900wdt_busy);
149 return 0;
150 }
151
152 static const struct watchdog_info nuc900_wdt_info = {
153 .identity = "nuc900 watchdog",
154 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
155 WDIOF_MAGICCLOSE,
156 };
157
nuc900_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)158 static long nuc900_wdt_ioctl(struct file *file,
159 unsigned int cmd, unsigned long arg)
160 {
161 void __user *argp = (void __user *)arg;
162 int __user *p = argp;
163 int new_value;
164
165 switch (cmd) {
166 case WDIOC_GETSUPPORT:
167 return copy_to_user(argp, &nuc900_wdt_info,
168 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
169 case WDIOC_GETSTATUS:
170 case WDIOC_GETBOOTSTATUS:
171 return put_user(0, p);
172
173 case WDIOC_KEEPALIVE:
174 nuc900_wdt_ping();
175 return 0;
176
177 case WDIOC_SETTIMEOUT:
178 if (get_user(new_value, p))
179 return -EFAULT;
180
181 heartbeat = new_value;
182 nuc900_wdt_ping();
183
184 return put_user(new_value, p);
185 case WDIOC_GETTIMEOUT:
186 return put_user(heartbeat, p);
187 default:
188 return -ENOTTY;
189 }
190 }
191
nuc900_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)192 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
193 size_t len, loff_t *ppos)
194 {
195 if (!len)
196 return 0;
197
198 /* Scan for magic character */
199 if (!nowayout) {
200 size_t i;
201
202 nuc900_wdt->expect_close = 0;
203
204 for (i = 0; i < len; i++) {
205 char c;
206 if (get_user(c, data + i))
207 return -EFAULT;
208 if (c == 'V') {
209 nuc900_wdt->expect_close = 42;
210 break;
211 }
212 }
213 }
214
215 nuc900_wdt_ping();
216 return len;
217 }
218
nuc900_wdt_timer_ping(struct timer_list * unused)219 static void nuc900_wdt_timer_ping(struct timer_list *unused)
220 {
221 if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
222 nuc900_wdt_keepalive();
223 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
224 } else
225 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
226 }
227
228 static const struct file_operations nuc900wdt_fops = {
229 .owner = THIS_MODULE,
230 .llseek = no_llseek,
231 .unlocked_ioctl = nuc900_wdt_ioctl,
232 .open = nuc900_wdt_open,
233 .release = nuc900_wdt_close,
234 .write = nuc900_wdt_write,
235 };
236
237 static struct miscdevice nuc900wdt_miscdev = {
238 .minor = WATCHDOG_MINOR,
239 .name = "watchdog",
240 .fops = &nuc900wdt_fops,
241 };
242
nuc900wdt_probe(struct platform_device * pdev)243 static int nuc900wdt_probe(struct platform_device *pdev)
244 {
245 struct resource *res;
246 int ret = 0;
247
248 nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
249 GFP_KERNEL);
250 if (!nuc900_wdt)
251 return -ENOMEM;
252
253 nuc900_wdt->pdev = pdev;
254
255 spin_lock_init(&nuc900_wdt->wdt_lock);
256
257 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
258 nuc900_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
259 if (IS_ERR(nuc900_wdt->wdt_base))
260 return PTR_ERR(nuc900_wdt->wdt_base);
261
262 nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
263 if (IS_ERR(nuc900_wdt->wdt_clock)) {
264 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
265 return PTR_ERR(nuc900_wdt->wdt_clock);
266 }
267
268 clk_enable(nuc900_wdt->wdt_clock);
269
270 timer_setup(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
271
272 ret = misc_register(&nuc900wdt_miscdev);
273 if (ret) {
274 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
275 WATCHDOG_MINOR, ret);
276 goto err_clk;
277 }
278
279 return 0;
280
281 err_clk:
282 clk_disable(nuc900_wdt->wdt_clock);
283 return ret;
284 }
285
nuc900wdt_remove(struct platform_device * pdev)286 static int nuc900wdt_remove(struct platform_device *pdev)
287 {
288 misc_deregister(&nuc900wdt_miscdev);
289
290 clk_disable(nuc900_wdt->wdt_clock);
291
292 return 0;
293 }
294
295 static struct platform_driver nuc900wdt_driver = {
296 .probe = nuc900wdt_probe,
297 .remove = nuc900wdt_remove,
298 .driver = {
299 .name = "nuc900-wdt",
300 },
301 };
302
303 module_platform_driver(nuc900wdt_driver);
304
305 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
306 MODULE_DESCRIPTION("Watchdog driver for NUC900");
307 MODULE_LICENSE("GPL");
308 MODULE_ALIAS("platform:nuc900-wdt");
309
