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14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/moduleparam.h>
18#include <linux/errno.h>
19#include <linux/miscdevice.h>
20#include <linux/platform_device.h>
21#include <linux/watchdog.h>
22#include <linux/fs.h>
23#include <linux/ioport.h>
24#include <linux/io.h>
25#include <linux/uaccess.h>
26#include <linux/clk.h>
27
28#include <asm/addrspace.h>
29#include <asm/mach-ar7/ar7.h>
30
31#define LONGNAME "TI AR7 Watchdog Timer"
32
33MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
34MODULE_DESCRIPTION(LONGNAME);
35MODULE_LICENSE("GPL");
36
37static int margin = 60;
38module_param(margin, int, 0);
39MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
40
41static bool nowayout = WATCHDOG_NOWAYOUT;
42module_param(nowayout, bool, 0);
43MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
44
45#define READ_REG(x) readl((void __iomem *)&(x))
46#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
47
48struct ar7_wdt {
49 u32 kick_lock;
50 u32 kick;
51 u32 change_lock;
52 u32 change;
53 u32 disable_lock;
54 u32 disable;
55 u32 prescale_lock;
56 u32 prescale;
57};
58
59static unsigned long wdt_is_open;
60static unsigned expect_close;
61static DEFINE_SPINLOCK(wdt_lock);
62
63
64#define prescale_value 0xffff
65
66
67static struct resource *ar7_regs_wdt;
68
69static struct ar7_wdt *ar7_wdt;
70
71static struct clk *vbus_clk;
72
73static void ar7_wdt_kick(u32 value)
74{
75 WRITE_REG(ar7_wdt->kick_lock, 0x5555);
76 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
77 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
78 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
79 WRITE_REG(ar7_wdt->kick, value);
80 return;
81 }
82 }
83 pr_err("failed to unlock WDT kick reg\n");
84}
85
86static void ar7_wdt_prescale(u32 value)
87{
88 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
89 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
90 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
91 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
92 WRITE_REG(ar7_wdt->prescale, value);
93 return;
94 }
95 }
96 pr_err("failed to unlock WDT prescale reg\n");
97}
98
99static void ar7_wdt_change(u32 value)
100{
101 WRITE_REG(ar7_wdt->change_lock, 0x6666);
102 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
103 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
104 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
105 WRITE_REG(ar7_wdt->change, value);
106 return;
107 }
108 }
109 pr_err("failed to unlock WDT change reg\n");
110}
111
112static void ar7_wdt_disable(u32 value)
113{
114 WRITE_REG(ar7_wdt->disable_lock, 0x7777);
115 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
116 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
117 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
118 WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
119 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
120 WRITE_REG(ar7_wdt->disable, value);
121 return;
122 }
123 }
124 }
125 pr_err("failed to unlock WDT disable reg\n");
126}
127
128static void ar7_wdt_update_margin(int new_margin)
129{
130 u32 change;
131 u32 vbus_rate;
132
133 vbus_rate = clk_get_rate(vbus_clk);
134 change = new_margin * (vbus_rate / prescale_value);
135 if (change < 1)
136 change = 1;
137 if (change > 0xffff)
138 change = 0xffff;
139 ar7_wdt_change(change);
140 margin = change * prescale_value / vbus_rate;
141 pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
142 margin, prescale_value, change, vbus_rate);
143}
144
145static void ar7_wdt_enable_wdt(void)
146{
147 pr_debug("enabling watchdog timer\n");
148 ar7_wdt_disable(1);
149 ar7_wdt_kick(1);
150}
151
152static void ar7_wdt_disable_wdt(void)
153{
154 pr_debug("disabling watchdog timer\n");
155 ar7_wdt_disable(0);
156}
157
158static int ar7_wdt_open(struct inode *inode, struct file *file)
159{
160
161 if (test_and_set_bit(0, &wdt_is_open))
162 return -EBUSY;
163 ar7_wdt_enable_wdt();
164 expect_close = 0;
165
166 return stream_open(inode, file);
167}
168
169static int ar7_wdt_release(struct inode *inode, struct file *file)
170{
171 if (!expect_close)
172 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
173 else if (!nowayout)
174 ar7_wdt_disable_wdt();
175 clear_bit(0, &wdt_is_open);
176 return 0;
177}
178
179static ssize_t ar7_wdt_write(struct file *file, const char *data,
180 size_t len, loff_t *ppos)
181{
182
183 if (len) {
184 size_t i;
185
186 spin_lock(&wdt_lock);
187 ar7_wdt_kick(1);
188 spin_unlock(&wdt_lock);
189
190 expect_close = 0;
191 for (i = 0; i < len; ++i) {
192 char c;
193 if (get_user(c, data + i))
194 return -EFAULT;
195 if (c == 'V')
196 expect_close = 1;
197 }
198
199 }
200 return len;
201}
202
203static long ar7_wdt_ioctl(struct file *file,
204 unsigned int cmd, unsigned long arg)
205{
206 static const struct watchdog_info ident = {
207 .identity = LONGNAME,
208 .firmware_version = 1,
209 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
210 WDIOF_MAGICCLOSE),
211 };
212 int new_margin;
213
214 switch (cmd) {
215 case WDIOC_GETSUPPORT:
216 if (copy_to_user((struct watchdog_info *)arg, &ident,
217 sizeof(ident)))
218 return -EFAULT;
219 return 0;
220 case WDIOC_GETSTATUS:
221 case WDIOC_GETBOOTSTATUS:
222 if (put_user(0, (int *)arg))
223 return -EFAULT;
224 return 0;
225 case WDIOC_KEEPALIVE:
226 ar7_wdt_kick(1);
227 return 0;
228 case WDIOC_SETTIMEOUT:
229 if (get_user(new_margin, (int *)arg))
230 return -EFAULT;
231 if (new_margin < 1)
232 return -EINVAL;
233
234 spin_lock(&wdt_lock);
235 ar7_wdt_update_margin(new_margin);
236 ar7_wdt_kick(1);
237 spin_unlock(&wdt_lock);
238 fallthrough;
239 case WDIOC_GETTIMEOUT:
240 if (put_user(margin, (int *)arg))
241 return -EFAULT;
242 return 0;
243 default:
244 return -ENOTTY;
245 }
246}
247
248static const struct file_operations ar7_wdt_fops = {
249 .owner = THIS_MODULE,
250 .write = ar7_wdt_write,
251 .unlocked_ioctl = ar7_wdt_ioctl,
252 .compat_ioctl = compat_ptr_ioctl,
253 .open = ar7_wdt_open,
254 .release = ar7_wdt_release,
255 .llseek = no_llseek,
256};
257
258static struct miscdevice ar7_wdt_miscdev = {
259 .minor = WATCHDOG_MINOR,
260 .name = "watchdog",
261 .fops = &ar7_wdt_fops,
262};
263
264static int ar7_wdt_probe(struct platform_device *pdev)
265{
266 int rc;
267
268 ar7_regs_wdt =
269 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
270 ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
271 if (IS_ERR(ar7_wdt))
272 return PTR_ERR(ar7_wdt);
273
274 vbus_clk = clk_get(NULL, "vbus");
275 if (IS_ERR(vbus_clk)) {
276 pr_err("could not get vbus clock\n");
277 return PTR_ERR(vbus_clk);
278 }
279
280 ar7_wdt_disable_wdt();
281 ar7_wdt_prescale(prescale_value);
282 ar7_wdt_update_margin(margin);
283
284 rc = misc_register(&ar7_wdt_miscdev);
285 if (rc) {
286 pr_err("unable to register misc device\n");
287 goto out;
288 }
289 return 0;
290
291out:
292 clk_put(vbus_clk);
293 vbus_clk = NULL;
294 return rc;
295}
296
297static int ar7_wdt_remove(struct platform_device *pdev)
298{
299 misc_deregister(&ar7_wdt_miscdev);
300 clk_put(vbus_clk);
301 vbus_clk = NULL;
302 return 0;
303}
304
305static void ar7_wdt_shutdown(struct platform_device *pdev)
306{
307 if (!nowayout)
308 ar7_wdt_disable_wdt();
309}
310
311static struct platform_driver ar7_wdt_driver = {
312 .probe = ar7_wdt_probe,
313 .remove = ar7_wdt_remove,
314 .shutdown = ar7_wdt_shutdown,
315 .driver = {
316 .name = "ar7_wdt",
317 },
318};
319
320module_platform_driver(ar7_wdt_driver);
321
