Root/drivers/watchdog/alim7101_wdt.c

1/*
2 * ALi M7101 PMU Computer Watchdog Timer driver
3 *
4 * Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
5 * and the Cobalt kernel WDT timer driver by Tim Hockin
6 * <thockin@cobaltnet.com>
7 *
8 * (c)2002 Steve Hill <steve@navaho.co.uk>
9 *
10 * This WDT driver is different from most other Linux WDT
11 * drivers in that the driver will ping the watchdog by itself,
12 * because this particular WDT has a very short timeout (1.6
13 * seconds) and it would be insane to count on any userspace
14 * daemon always getting scheduled within that time frame.
15 *
16 * Additions:
17 * Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
18 * found on very old cobalt hardware.
19 * -- Mike Waychison <michael.waychison@sun.com>
20 */
21
22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/moduleparam.h>
26#include <linux/types.h>
27#include <linux/timer.h>
28#include <linux/miscdevice.h>
29#include <linux/watchdog.h>
30#include <linux/ioport.h>
31#include <linux/notifier.h>
32#include <linux/reboot.h>
33#include <linux/init.h>
34#include <linux/fs.h>
35#include <linux/pci.h>
36#include <linux/io.h>
37#include <linux/uaccess.h>
38
39
40#define WDT_ENABLE 0x9C
41#define WDT_DISABLE 0x8C
42
43#define ALI_7101_WDT 0x92
44#define ALI_7101_GPIO 0x7D
45#define ALI_7101_GPIO_O 0x7E
46#define ALI_WDT_ARM 0x01
47
48/*
49 * We're going to use a 1 second timeout.
50 * If we reset the watchdog every ~250ms we should be safe. */
51
52#define WDT_INTERVAL (HZ/4+1)
53
54/*
55 * We must not require too good response from the userspace daemon.
56 * Here we require the userspace daemon to send us a heartbeat
57 * char to /dev/watchdog every 30 seconds.
58 */
59
60#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
61/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
62static int timeout = WATCHDOG_TIMEOUT;
63module_param(timeout, int, 0);
64MODULE_PARM_DESC(timeout,
65        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
66                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
67
68static int use_gpio; /* Use the pic (for a1d revision alim7101) */
69module_param(use_gpio, int, 0);
70MODULE_PARM_DESC(use_gpio,
71        "Use the gpio watchdog (required by old cobalt boards).");
72
73static void wdt_timer_ping(unsigned long);
74static DEFINE_TIMER(timer, wdt_timer_ping, 0, 1);
75static unsigned long next_heartbeat;
76static unsigned long wdt_is_open;
77static char wdt_expect_close;
78static struct pci_dev *alim7101_pmu;
79
80static bool nowayout = WATCHDOG_NOWAYOUT;
81module_param(nowayout, bool, 0);
82MODULE_PARM_DESC(nowayout,
83        "Watchdog cannot be stopped once started (default="
84                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
85
86/*
87 * Whack the dog
88 */
89
90static void wdt_timer_ping(unsigned long data)
91{
92    /* If we got a heartbeat pulse within the WDT_US_INTERVAL
93     * we agree to ping the WDT
94     */
95    char tmp;
96
97    if (time_before(jiffies, next_heartbeat)) {
98        /* Ping the WDT (this is actually a disarm/arm sequence) */
99        pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
100        pci_write_config_byte(alim7101_pmu,
101                    ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
102        pci_write_config_byte(alim7101_pmu,
103                    ALI_7101_WDT, (tmp | ALI_WDT_ARM));
104        if (use_gpio) {
105            pci_read_config_byte(alim7101_pmu,
106                    ALI_7101_GPIO_O, &tmp);
107            pci_write_config_byte(alim7101_pmu,
108                    ALI_7101_GPIO_O, tmp | 0x20);
109            pci_write_config_byte(alim7101_pmu,
110                    ALI_7101_GPIO_O, tmp & ~0x20);
111        }
112    } else {
113        pr_warn("Heartbeat lost! Will not ping the watchdog\n");
114    }
115    /* Re-set the timer interval */
116    mod_timer(&timer, jiffies + WDT_INTERVAL);
117}
118
119/*
120 * Utility routines
121 */
122
123static void wdt_change(int writeval)
124{
125    char tmp;
126
127    pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
128    if (writeval == WDT_ENABLE) {
129        pci_write_config_byte(alim7101_pmu,
130                    ALI_7101_WDT, (tmp | ALI_WDT_ARM));
131        if (use_gpio) {
132            pci_read_config_byte(alim7101_pmu,
133                    ALI_7101_GPIO_O, &tmp);
134            pci_write_config_byte(alim7101_pmu,
135                    ALI_7101_GPIO_O, tmp & ~0x20);
136        }
137
138    } else {
139        pci_write_config_byte(alim7101_pmu,
140                    ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
141        if (use_gpio) {
142            pci_read_config_byte(alim7101_pmu,
143                    ALI_7101_GPIO_O, &tmp);
144            pci_write_config_byte(alim7101_pmu,
145                    ALI_7101_GPIO_O, tmp | 0x20);
146        }
147    }
148}
149
150static void wdt_startup(void)
151{
152    next_heartbeat = jiffies + (timeout * HZ);
153
154    /* We must enable before we kick off the timer in case the timer
155       occurs as we ping it */
156
157    wdt_change(WDT_ENABLE);
158
159    /* Start the timer */
160    mod_timer(&timer, jiffies + WDT_INTERVAL);
161
162    pr_info("Watchdog timer is now enabled\n");
163}
164
165static void wdt_turnoff(void)
166{
167    /* Stop the timer */
168    del_timer_sync(&timer);
169    wdt_change(WDT_DISABLE);
170    pr_info("Watchdog timer is now disabled...\n");
171}
172
173static void wdt_keepalive(void)
174{
175    /* user land ping */
176    next_heartbeat = jiffies + (timeout * HZ);
177}
178
179/*
180 * /dev/watchdog handling
181 */
182
183static ssize_t fop_write(struct file *file, const char __user *buf,
184                        size_t count, loff_t *ppos)
185{
186    /* See if we got the magic character 'V' and reload the timer */
187    if (count) {
188        if (!nowayout) {
189            size_t ofs;
190
191            /* note: just in case someone wrote the magic character
192             * five months ago... */
193            wdt_expect_close = 0;
194
195            /* now scan */
196            for (ofs = 0; ofs != count; ofs++) {
197                char c;
198                if (get_user(c, buf + ofs))
199                    return -EFAULT;
200                if (c == 'V')
201                    wdt_expect_close = 42;
202            }
203        }
204        /* someone wrote to us, we should restart timer */
205        wdt_keepalive();
206    }
207    return count;
208}
209
210static int fop_open(struct inode *inode, struct file *file)
211{
212    /* Just in case we're already talking to someone... */
213    if (test_and_set_bit(0, &wdt_is_open))
214        return -EBUSY;
215    /* Good, fire up the show */
216    wdt_startup();
217    return nonseekable_open(inode, file);
218}
219
220static int fop_close(struct inode *inode, struct file *file)
221{
222    if (wdt_expect_close == 42)
223        wdt_turnoff();
224    else {
225        /* wim: shouldn't there be a: del_timer(&timer); */
226        pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
227    }
228    clear_bit(0, &wdt_is_open);
229    wdt_expect_close = 0;
230    return 0;
231}
232
233static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
234{
235    void __user *argp = (void __user *)arg;
236    int __user *p = argp;
237    static const struct watchdog_info ident = {
238        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
239                            | WDIOF_MAGICCLOSE,
240        .firmware_version = 1,
241        .identity = "ALiM7101",
242    };
243
244    switch (cmd) {
245    case WDIOC_GETSUPPORT:
246        return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
247    case WDIOC_GETSTATUS:
248    case WDIOC_GETBOOTSTATUS:
249        return put_user(0, p);
250    case WDIOC_SETOPTIONS:
251    {
252        int new_options, retval = -EINVAL;
253
254        if (get_user(new_options, p))
255            return -EFAULT;
256        if (new_options & WDIOS_DISABLECARD) {
257            wdt_turnoff();
258            retval = 0;
259        }
260        if (new_options & WDIOS_ENABLECARD) {
261            wdt_startup();
262            retval = 0;
263        }
264        return retval;
265    }
266    case WDIOC_KEEPALIVE:
267        wdt_keepalive();
268        return 0;
269    case WDIOC_SETTIMEOUT:
270    {
271        int new_timeout;
272
273        if (get_user(new_timeout, p))
274            return -EFAULT;
275        /* arbitrary upper limit */
276        if (new_timeout < 1 || new_timeout > 3600)
277            return -EINVAL;
278        timeout = new_timeout;
279        wdt_keepalive();
280        /* Fall through */
281    }
282    case WDIOC_GETTIMEOUT:
283        return put_user(timeout, p);
284    default:
285        return -ENOTTY;
286    }
287}
288
289static const struct file_operations wdt_fops = {
290    .owner = THIS_MODULE,
291    .llseek = no_llseek,
292    .write = fop_write,
293    .open = fop_open,
294    .release = fop_close,
295    .unlocked_ioctl = fop_ioctl,
296};
297
298static struct miscdevice wdt_miscdev = {
299    .minor = WATCHDOG_MINOR,
300    .name = "watchdog",
301    .fops = &wdt_fops,
302};
303
304/*
305 * Notifier for system down
306 */
307
308static int wdt_notify_sys(struct notifier_block *this,
309                    unsigned long code, void *unused)
310{
311    if (code == SYS_DOWN || code == SYS_HALT)
312        wdt_turnoff();
313
314    if (code == SYS_RESTART) {
315        /*
316         * Cobalt devices have no way of rebooting themselves other
317         * than getting the watchdog to pull reset, so we restart the
318         * watchdog on reboot with no heartbeat
319         */
320        wdt_change(WDT_ENABLE);
321        pr_info("Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second\n");
322    }
323    return NOTIFY_DONE;
324}
325
326/*
327 * The WDT needs to learn about soft shutdowns in order to
328 * turn the timebomb registers off.
329 */
330
331static struct notifier_block wdt_notifier = {
332    .notifier_call = wdt_notify_sys,
333};
334
335static void __exit alim7101_wdt_unload(void)
336{
337    wdt_turnoff();
338    /* Deregister */
339    misc_deregister(&wdt_miscdev);
340    unregister_reboot_notifier(&wdt_notifier);
341    pci_dev_put(alim7101_pmu);
342}
343
344static int __init alim7101_wdt_init(void)
345{
346    int rc = -EBUSY;
347    struct pci_dev *ali1543_south;
348    char tmp;
349
350    pr_info("Steve Hill <steve@navaho.co.uk>\n");
351    alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
352        NULL);
353    if (!alim7101_pmu) {
354        pr_info("ALi M7101 PMU not present - WDT not set\n");
355        return -EBUSY;
356    }
357
358    /* Set the WDT in the PMU to 1 second */
359    pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
360
361    ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
362        NULL);
363    if (!ali1543_south) {
364        pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
365        goto err_out;
366    }
367    pci_read_config_byte(ali1543_south, 0x5e, &tmp);
368    pci_dev_put(ali1543_south);
369    if ((tmp & 0x1e) == 0x00) {
370        if (!use_gpio) {
371            pr_info("Detected old alim7101 revision 'a1d'. If this is a cobalt board, set the 'use_gpio' module parameter.\n");
372            goto err_out;
373        }
374        nowayout = 1;
375    } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
376        pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
377        goto err_out;
378    }
379
380    if (timeout < 1 || timeout > 3600) {
381        /* arbitrary upper limit */
382        timeout = WATCHDOG_TIMEOUT;
383        pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
384            timeout);
385    }
386
387    rc = register_reboot_notifier(&wdt_notifier);
388    if (rc) {
389        pr_err("cannot register reboot notifier (err=%d)\n", rc);
390        goto err_out;
391    }
392
393    rc = misc_register(&wdt_miscdev);
394    if (rc) {
395        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
396               wdt_miscdev.minor, rc);
397        goto err_out_reboot;
398    }
399
400    if (nowayout)
401        __module_get(THIS_MODULE);
402
403    pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
404        timeout, nowayout);
405    return 0;
406
407err_out_reboot:
408    unregister_reboot_notifier(&wdt_notifier);
409err_out:
410    pci_dev_put(alim7101_pmu);
411    return rc;
412}
413
414module_init(alim7101_wdt_init);
415module_exit(alim7101_wdt_unload);
416
417static DEFINE_PCI_DEVICE_TABLE(alim7101_pci_tbl) __used = {
418    { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
419    { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
420    { }
421};
422
423MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
424
425MODULE_AUTHOR("Steve Hill");
426MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
427MODULE_LICENSE("GPL");
428MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
429

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