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12#include <linux/bitops.h>
13#include <linux/errno.h>
14#include <linux/fs.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/clk.h>
18#include <linux/kernel.h>
19#include <linux/miscdevice.h>
20#include <linux/module.h>
21#include <linux/moduleparam.h>
22#include <linux/platform_device.h>
23#include <linux/slab.h>
24#include <linux/interrupt.h>
25#include <linux/types.h>
26#include <linux/watchdog.h>
27#include <linux/uaccess.h>
28
29#define REG_WTCR 0x1c
30#define WTCLK (0x01 << 10)
31#define WTE (0x01 << 7)
32#define WTIS (0x03 << 4)
33#define WTIF (0x01 << 3)
34#define WTRF (0x01 << 2)
35#define WTRE (0x01 << 1)
36#define WTR (0x01 << 0)
37
38
39
40
41
42
43
44
45
46
47
48
49#define WDT_HW_TIMEOUT 0x02
50#define WDT_TIMEOUT (HZ/2)
51#define WDT_HEARTBEAT 15
52
53static int heartbeat = WDT_HEARTBEAT;
54module_param(heartbeat, int, 0);
55MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
56 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
57
58static bool nowayout = WATCHDOG_NOWAYOUT;
59module_param(nowayout, bool, 0);
60MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
61 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
62
63struct nuc900_wdt {
64 struct clk *wdt_clock;
65 struct platform_device *pdev;
66 void __iomem *wdt_base;
67 char expect_close;
68 struct timer_list timer;
69 spinlock_t wdt_lock;
70 unsigned long next_heartbeat;
71};
72
73static unsigned long nuc900wdt_busy;
74static struct nuc900_wdt *nuc900_wdt;
75
76static inline void nuc900_wdt_keepalive(void)
77{
78 unsigned int val;
79
80 spin_lock(&nuc900_wdt->wdt_lock);
81
82 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
83 val |= (WTR | WTIF);
84 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
85
86 spin_unlock(&nuc900_wdt->wdt_lock);
87}
88
89static inline void nuc900_wdt_start(void)
90{
91 unsigned int val;
92
93 spin_lock(&nuc900_wdt->wdt_lock);
94
95 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
96 val |= (WTRE | WTE | WTR | WTCLK | WTIF);
97 val &= ~WTIS;
98 val |= (WDT_HW_TIMEOUT << 0x04);
99 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
100
101 spin_unlock(&nuc900_wdt->wdt_lock);
102
103 nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
104 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
105}
106
107static inline void nuc900_wdt_stop(void)
108{
109 unsigned int val;
110
111 del_timer(&nuc900_wdt->timer);
112
113 spin_lock(&nuc900_wdt->wdt_lock);
114
115 val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
116 val &= ~WTE;
117 __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
118
119 spin_unlock(&nuc900_wdt->wdt_lock);
120}
121
122static inline void nuc900_wdt_ping(void)
123{
124 nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
125}
126
127static int nuc900_wdt_open(struct inode *inode, struct file *file)
128{
129
130 if (test_and_set_bit(0, &nuc900wdt_busy))
131 return -EBUSY;
132
133 nuc900_wdt_start();
134
135 return nonseekable_open(inode, file);
136}
137
138static int nuc900_wdt_close(struct inode *inode, struct file *file)
139{
140 if (nuc900_wdt->expect_close == 42)
141 nuc900_wdt_stop();
142 else {
143 dev_crit(&nuc900_wdt->pdev->dev,
144 "Unexpected close, not stopping watchdog!\n");
145 nuc900_wdt_ping();
146 }
147
148 nuc900_wdt->expect_close = 0;
149 clear_bit(0, &nuc900wdt_busy);
150 return 0;
151}
152
153static const struct watchdog_info nuc900_wdt_info = {
154 .identity = "nuc900 watchdog",
155 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
156 WDIOF_MAGICCLOSE,
157};
158
159static long nuc900_wdt_ioctl(struct file *file,
160 unsigned int cmd, unsigned long arg)
161{
162 void __user *argp = (void __user *)arg;
163 int __user *p = argp;
164 int new_value;
165
166 switch (cmd) {
167 case WDIOC_GETSUPPORT:
168 return copy_to_user(argp, &nuc900_wdt_info,
169 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
170 case WDIOC_GETSTATUS:
171 case WDIOC_GETBOOTSTATUS:
172 return put_user(0, p);
173
174 case WDIOC_KEEPALIVE:
175 nuc900_wdt_ping();
176 return 0;
177
178 case WDIOC_SETTIMEOUT:
179 if (get_user(new_value, p))
180 return -EFAULT;
181
182 heartbeat = new_value;
183 nuc900_wdt_ping();
184
185 return put_user(new_value, p);
186 case WDIOC_GETTIMEOUT:
187 return put_user(heartbeat, p);
188 default:
189 return -ENOTTY;
190 }
191}
192
193static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
194 size_t len, loff_t *ppos)
195{
196 if (!len)
197 return 0;
198
199
200 if (!nowayout) {
201 size_t i;
202
203 nuc900_wdt->expect_close = 0;
204
205 for (i = 0; i < len; i++) {
206 char c;
207 if (get_user(c, data + i))
208 return -EFAULT;
209 if (c == 'V') {
210 nuc900_wdt->expect_close = 42;
211 break;
212 }
213 }
214 }
215
216 nuc900_wdt_ping();
217 return len;
218}
219
220static void nuc900_wdt_timer_ping(unsigned long data)
221{
222 if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
223 nuc900_wdt_keepalive();
224 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
225 } else
226 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
227}
228
229static const struct file_operations nuc900wdt_fops = {
230 .owner = THIS_MODULE,
231 .llseek = no_llseek,
232 .unlocked_ioctl = nuc900_wdt_ioctl,
233 .open = nuc900_wdt_open,
234 .release = nuc900_wdt_close,
235 .write = nuc900_wdt_write,
236};
237
238static struct miscdevice nuc900wdt_miscdev = {
239 .minor = WATCHDOG_MINOR,
240 .name = "watchdog",
241 .fops = &nuc900wdt_fops,
242};
243
244static int nuc900wdt_probe(struct platform_device *pdev)
245{
246 struct resource *res;
247 int ret = 0;
248
249 nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
250 GFP_KERNEL);
251 if (!nuc900_wdt)
252 return -ENOMEM;
253
254 nuc900_wdt->pdev = pdev;
255
256 spin_lock_init(&nuc900_wdt->wdt_lock);
257
258 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
259 nuc900_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
260 if (IS_ERR(nuc900_wdt->wdt_base))
261 return PTR_ERR(nuc900_wdt->wdt_base);
262
263 nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
264 if (IS_ERR(nuc900_wdt->wdt_clock)) {
265 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
266 return PTR_ERR(nuc900_wdt->wdt_clock);
267 }
268
269 clk_enable(nuc900_wdt->wdt_clock);
270
271 setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
272
273 ret = misc_register(&nuc900wdt_miscdev);
274 if (ret) {
275 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
276 WATCHDOG_MINOR, ret);
277 goto err_clk;
278 }
279
280 return 0;
281
282err_clk:
283 clk_disable(nuc900_wdt->wdt_clock);
284 return ret;
285}
286
287static int nuc900wdt_remove(struct platform_device *pdev)
288{
289 misc_deregister(&nuc900wdt_miscdev);
290
291 clk_disable(nuc900_wdt->wdt_clock);
292
293 return 0;
294}
295
296static struct platform_driver nuc900wdt_driver = {
297 .probe = nuc900wdt_probe,
298 .remove = nuc900wdt_remove,
299 .driver = {
300 .name = "nuc900-wdt",
301 .owner = THIS_MODULE,
302 },
303};
304
305module_platform_driver(nuc900wdt_driver);
306
307MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
308MODULE_DESCRIPTION("Watchdog driver for NUC900");
309MODULE_LICENSE("GPL");
310MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
311MODULE_ALIAS("platform:nuc900-wdt");
312
