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26#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27
28#include <linux/module.h>
29#include <linux/moduleparam.h>
30#include <linux/errno.h>
31#include <linux/miscdevice.h>
32#include <linux/platform_device.h>
33#include <linux/watchdog.h>
34#include <linux/fs.h>
35#include <linux/ioport.h>
36#include <linux/io.h>
37#include <linux/uaccess.h>
38#include <linux/clk.h>
39
40#include <asm/addrspace.h>
41#include <asm/mach-ar7/ar7.h>
42
43#define LONGNAME "TI AR7 Watchdog Timer"
44
45MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
46MODULE_DESCRIPTION(LONGNAME);
47MODULE_LICENSE("GPL");
48
49static int margin = 60;
50module_param(margin, int, 0);
51MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
52
53static bool nowayout = WATCHDOG_NOWAYOUT;
54module_param(nowayout, bool, 0);
55MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
56
57#define READ_REG(x) readl((void __iomem *)&(x))
58#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
59
60struct ar7_wdt {
61 u32 kick_lock;
62 u32 kick;
63 u32 change_lock;
64 u32 change;
65 u32 disable_lock;
66 u32 disable;
67 u32 prescale_lock;
68 u32 prescale;
69};
70
71static unsigned long wdt_is_open;
72static unsigned expect_close;
73static DEFINE_SPINLOCK(wdt_lock);
74
75
76#define prescale_value 0xffff
77
78
79static struct resource *ar7_regs_wdt;
80
81static struct ar7_wdt *ar7_wdt;
82
83static struct clk *vbus_clk;
84
85static void ar7_wdt_kick(u32 value)
86{
87 WRITE_REG(ar7_wdt->kick_lock, 0x5555);
88 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
89 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
90 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
91 WRITE_REG(ar7_wdt->kick, value);
92 return;
93 }
94 }
95 pr_err("failed to unlock WDT kick reg\n");
96}
97
98static void ar7_wdt_prescale(u32 value)
99{
100 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
101 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
102 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
103 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
104 WRITE_REG(ar7_wdt->prescale, value);
105 return;
106 }
107 }
108 pr_err("failed to unlock WDT prescale reg\n");
109}
110
111static void ar7_wdt_change(u32 value)
112{
113 WRITE_REG(ar7_wdt->change_lock, 0x6666);
114 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
115 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
116 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
117 WRITE_REG(ar7_wdt->change, value);
118 return;
119 }
120 }
121 pr_err("failed to unlock WDT change reg\n");
122}
123
124static void ar7_wdt_disable(u32 value)
125{
126 WRITE_REG(ar7_wdt->disable_lock, 0x7777);
127 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
128 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
129 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
130 WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
131 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
132 WRITE_REG(ar7_wdt->disable, value);
133 return;
134 }
135 }
136 }
137 pr_err("failed to unlock WDT disable reg\n");
138}
139
140static void ar7_wdt_update_margin(int new_margin)
141{
142 u32 change;
143 u32 vbus_rate;
144
145 vbus_rate = clk_get_rate(vbus_clk);
146 change = new_margin * (vbus_rate / prescale_value);
147 if (change < 1)
148 change = 1;
149 if (change > 0xffff)
150 change = 0xffff;
151 ar7_wdt_change(change);
152 margin = change * prescale_value / vbus_rate;
153 pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
154 margin, prescale_value, change, vbus_rate);
155}
156
157static void ar7_wdt_enable_wdt(void)
158{
159 pr_debug("enabling watchdog timer\n");
160 ar7_wdt_disable(1);
161 ar7_wdt_kick(1);
162}
163
164static void ar7_wdt_disable_wdt(void)
165{
166 pr_debug("disabling watchdog timer\n");
167 ar7_wdt_disable(0);
168}
169
170static int ar7_wdt_open(struct inode *inode, struct file *file)
171{
172
173 if (test_and_set_bit(0, &wdt_is_open))
174 return -EBUSY;
175 ar7_wdt_enable_wdt();
176 expect_close = 0;
177
178 return nonseekable_open(inode, file);
179}
180
181static int ar7_wdt_release(struct inode *inode, struct file *file)
182{
183 if (!expect_close)
184 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
185 else if (!nowayout)
186 ar7_wdt_disable_wdt();
187 clear_bit(0, &wdt_is_open);
188 return 0;
189}
190
191static ssize_t ar7_wdt_write(struct file *file, const char *data,
192 size_t len, loff_t *ppos)
193{
194
195 if (len) {
196 size_t i;
197
198 spin_lock(&wdt_lock);
199 ar7_wdt_kick(1);
200 spin_unlock(&wdt_lock);
201
202 expect_close = 0;
203 for (i = 0; i < len; ++i) {
204 char c;
205 if (get_user(c, data + i))
206 return -EFAULT;
207 if (c == 'V')
208 expect_close = 1;
209 }
210
211 }
212 return len;
213}
214
215static long ar7_wdt_ioctl(struct file *file,
216 unsigned int cmd, unsigned long arg)
217{
218 static const struct watchdog_info ident = {
219 .identity = LONGNAME,
220 .firmware_version = 1,
221 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
222 WDIOF_MAGICCLOSE),
223 };
224 int new_margin;
225
226 switch (cmd) {
227 case WDIOC_GETSUPPORT:
228 if (copy_to_user((struct watchdog_info *)arg, &ident,
229 sizeof(ident)))
230 return -EFAULT;
231 return 0;
232 case WDIOC_GETSTATUS:
233 case WDIOC_GETBOOTSTATUS:
234 if (put_user(0, (int *)arg))
235 return -EFAULT;
236 return 0;
237 case WDIOC_KEEPALIVE:
238 ar7_wdt_kick(1);
239 return 0;
240 case WDIOC_SETTIMEOUT:
241 if (get_user(new_margin, (int *)arg))
242 return -EFAULT;
243 if (new_margin < 1)
244 return -EINVAL;
245
246 spin_lock(&wdt_lock);
247 ar7_wdt_update_margin(new_margin);
248 ar7_wdt_kick(1);
249 spin_unlock(&wdt_lock);
250
251 case WDIOC_GETTIMEOUT:
252 if (put_user(margin, (int *)arg))
253 return -EFAULT;
254 return 0;
255 default:
256 return -ENOTTY;
257 }
258}
259
260static const struct file_operations ar7_wdt_fops = {
261 .owner = THIS_MODULE,
262 .write = ar7_wdt_write,
263 .unlocked_ioctl = ar7_wdt_ioctl,
264 .open = ar7_wdt_open,
265 .release = ar7_wdt_release,
266 .llseek = no_llseek,
267};
268
269static struct miscdevice ar7_wdt_miscdev = {
270 .minor = WATCHDOG_MINOR,
271 .name = "watchdog",
272 .fops = &ar7_wdt_fops,
273};
274
275static int ar7_wdt_probe(struct platform_device *pdev)
276{
277 int rc;
278
279 ar7_regs_wdt =
280 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
281 ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
282 if (IS_ERR(ar7_wdt))
283 return PTR_ERR(ar7_wdt);
284
285 vbus_clk = clk_get(NULL, "vbus");
286 if (IS_ERR(vbus_clk)) {
287 pr_err("could not get vbus clock\n");
288 return PTR_ERR(vbus_clk);
289 }
290
291 ar7_wdt_disable_wdt();
292 ar7_wdt_prescale(prescale_value);
293 ar7_wdt_update_margin(margin);
294
295 rc = misc_register(&ar7_wdt_miscdev);
296 if (rc) {
297 pr_err("unable to register misc device\n");
298 goto out;
299 }
300 return 0;
301
302out:
303 clk_put(vbus_clk);
304 vbus_clk = NULL;
305 return rc;
306}
307
308static int ar7_wdt_remove(struct platform_device *pdev)
309{
310 misc_deregister(&ar7_wdt_miscdev);
311 clk_put(vbus_clk);
312 vbus_clk = NULL;
313 return 0;
314}
315
316static void ar7_wdt_shutdown(struct platform_device *pdev)
317{
318 if (!nowayout)
319 ar7_wdt_disable_wdt();
320}
321
322static struct platform_driver ar7_wdt_driver = {
323 .probe = ar7_wdt_probe,
324 .remove = ar7_wdt_remove,
325 .shutdown = ar7_wdt_shutdown,
326 .driver = {
327 .name = "ar7_wdt",
328 },
329};
330
331module_platform_driver(ar7_wdt_driver);
332
