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[linux-2.6-omap-h63xx.git] / drivers / s390 / char / monreader.c
1 /*
2  * drivers/s390/char/monreader.c
3  *
4  * Character device driver for reading z/VM *MONITOR service records.
5  *
6  *   Copyright IBM Corp. 2004, 2008
7  *   Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
8  */
9
10 #define KMSG_COMPONENT "monreader"
11 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
12
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/init.h>
16 #include <linux/smp_lock.h>
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/miscdevice.h>
21 #include <linux/ctype.h>
22 #include <linux/spinlock.h>
23 #include <linux/interrupt.h>
24 #include <linux/poll.h>
25 #include <net/iucv/iucv.h>
26 #include <asm/uaccess.h>
27 #include <asm/ebcdic.h>
28 #include <asm/extmem.h>
29
30
31 #define MON_COLLECT_SAMPLE 0x80
32 #define MON_COLLECT_EVENT  0x40
33 #define MON_SERVICE        "*MONITOR"
34 #define MON_IN_USE         0x01
35 #define MON_MSGLIM         255
36
37 static char mon_dcss_name[9] = "MONDCSS\0";
38
39 struct mon_msg {
40         u32 pos;
41         u32 mca_offset;
42         struct iucv_message msg;
43         char msglim_reached;
44         char replied_msglim;
45 };
46
47 struct mon_private {
48         struct iucv_path *path;
49         struct mon_msg *msg_array[MON_MSGLIM];
50         unsigned int   write_index;
51         unsigned int   read_index;
52         atomic_t msglim_count;
53         atomic_t read_ready;
54         atomic_t iucv_connected;
55         atomic_t iucv_severed;
56 };
57
58 static unsigned long mon_in_use = 0;
59
60 static unsigned long mon_dcss_start;
61 static unsigned long mon_dcss_end;
62
63 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
64 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
65
66 static u8 user_data_connect[16] = {
67         /* Version code, must be 0x01 for shared mode */
68         0x01,
69         /* what to collect */
70         MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
71         /* DCSS name in EBCDIC, 8 bytes padded with blanks */
72         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
73         0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
74 };
75
76 static u8 user_data_sever[16] = {
77         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
78         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
79 };
80
81
82 /******************************************************************************
83  *                             helper functions                               *
84  *****************************************************************************/
85 /*
86  * Create the 8 bytes EBCDIC DCSS segment name from
87  * an ASCII name, incl. padding
88  */
89 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
90 {
91         int i;
92
93         for (i = 0; i < 8; i++) {
94                 if (ascii_name[i] == '\0')
95                         break;
96                 ebcdic_name[i] = toupper(ascii_name[i]);
97         };
98         for (; i < 8; i++)
99                 ebcdic_name[i] = ' ';
100         ASCEBC(ebcdic_name, 8);
101 }
102
103 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
104 {
105         return *(u32 *) &monmsg->msg.rmmsg;
106 }
107
108 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
109 {
110         return *(u32 *) &monmsg->msg.rmmsg[4];
111 }
112
113 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
114 {
115         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
116 }
117
118 static inline u32 mon_mca_size(struct mon_msg *monmsg)
119 {
120         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
121 }
122
123 static inline u32 mon_rec_start(struct mon_msg *monmsg)
124 {
125         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
126 }
127
128 static inline u32 mon_rec_end(struct mon_msg *monmsg)
129 {
130         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
131 }
132
133 static int mon_check_mca(struct mon_msg *monmsg)
134 {
135         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
136             (mon_rec_start(monmsg) < mon_dcss_start) ||
137             (mon_rec_end(monmsg) > mon_dcss_end) ||
138             (mon_mca_type(monmsg, 0) == 0) ||
139             (mon_mca_size(monmsg) % 12 != 0) ||
140             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
141             (mon_mca_end(monmsg) > mon_dcss_end) ||
142             (mon_mca_start(monmsg) < mon_dcss_start) ||
143             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
144                 return -EINVAL;
145         return 0;
146 }
147
148 static int mon_send_reply(struct mon_msg *monmsg,
149                           struct mon_private *monpriv)
150 {
151         int rc;
152
153         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
154                                 IUCV_IPRMDATA, NULL, 0);
155         atomic_dec(&monpriv->msglim_count);
156         if (likely(!monmsg->msglim_reached)) {
157                 monmsg->pos = 0;
158                 monmsg->mca_offset = 0;
159                 monpriv->read_index = (monpriv->read_index + 1) %
160                                       MON_MSGLIM;
161                 atomic_dec(&monpriv->read_ready);
162         } else
163                 monmsg->replied_msglim = 1;
164         if (rc) {
165                 pr_err("Reading monitor data failed with rc=%i\n", rc);
166                 return -EIO;
167         }
168         return 0;
169 }
170
171 static void mon_free_mem(struct mon_private *monpriv)
172 {
173         int i;
174
175         for (i = 0; i < MON_MSGLIM; i++)
176                 if (monpriv->msg_array[i])
177                         kfree(monpriv->msg_array[i]);
178         kfree(monpriv);
179 }
180
181 static struct mon_private *mon_alloc_mem(void)
182 {
183         int i;
184         struct mon_private *monpriv;
185
186         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
187         if (!monpriv)
188                 return NULL;
189         for (i = 0; i < MON_MSGLIM; i++) {
190                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
191                                                     GFP_KERNEL);
192                 if (!monpriv->msg_array[i]) {
193                         mon_free_mem(monpriv);
194                         return NULL;
195                 }
196         }
197         return monpriv;
198 }
199
200 static inline void mon_next_mca(struct mon_msg *monmsg)
201 {
202         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
203                 return;
204         monmsg->mca_offset += 12;
205         monmsg->pos = 0;
206 }
207
208 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
209 {
210         struct mon_msg *monmsg;
211
212         if (!atomic_read(&monpriv->read_ready))
213                 return NULL;
214         monmsg = monpriv->msg_array[monpriv->read_index];
215         if (unlikely(monmsg->replied_msglim)) {
216                 monmsg->replied_msglim = 0;
217                 monmsg->msglim_reached = 0;
218                 monmsg->pos = 0;
219                 monmsg->mca_offset = 0;
220                 monpriv->read_index = (monpriv->read_index + 1) %
221                                       MON_MSGLIM;
222                 atomic_dec(&monpriv->read_ready);
223                 return ERR_PTR(-EOVERFLOW);
224         }
225         return monmsg;
226 }
227
228
229 /******************************************************************************
230  *                               IUCV handler                                 *
231  *****************************************************************************/
232 static void mon_iucv_path_complete(struct iucv_path *path, u8 ipuser[16])
233 {
234         struct mon_private *monpriv = path->private;
235
236         atomic_set(&monpriv->iucv_connected, 1);
237         wake_up(&mon_conn_wait_queue);
238 }
239
240 static void mon_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
241 {
242         struct mon_private *monpriv = path->private;
243
244         pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
245                ipuser[0]);
246         iucv_path_sever(path, NULL);
247         atomic_set(&monpriv->iucv_severed, 1);
248         wake_up(&mon_conn_wait_queue);
249         wake_up_interruptible(&mon_read_wait_queue);
250 }
251
252 static void mon_iucv_message_pending(struct iucv_path *path,
253                                      struct iucv_message *msg)
254 {
255         struct mon_private *monpriv = path->private;
256
257         memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
258                msg, sizeof(*msg));
259         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
260                 pr_warning("The read queue for monitor data is full\n");
261                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
262         }
263         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
264         atomic_inc(&monpriv->read_ready);
265         wake_up_interruptible(&mon_read_wait_queue);
266 }
267
268 static struct iucv_handler monreader_iucv_handler = {
269         .path_complete   = mon_iucv_path_complete,
270         .path_severed    = mon_iucv_path_severed,
271         .message_pending = mon_iucv_message_pending,
272 };
273
274 /******************************************************************************
275  *                               file operations                              *
276  *****************************************************************************/
277 static int mon_open(struct inode *inode, struct file *filp)
278 {
279         struct mon_private *monpriv;
280         int rc;
281
282         /*
283          * only one user allowed
284          */
285         lock_kernel();
286         rc = -EBUSY;
287         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
288                 goto out;
289
290         rc = -ENOMEM;
291         monpriv = mon_alloc_mem();
292         if (!monpriv)
293                 goto out_use;
294
295         /*
296          * Connect to *MONITOR service
297          */
298         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
299         if (!monpriv->path)
300                 goto out_priv;
301         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
302                                MON_SERVICE, NULL, user_data_connect, monpriv);
303         if (rc) {
304                 pr_err("Connecting to the z/VM *MONITOR system service "
305                        "failed with rc=%i\n", rc);
306                 rc = -EIO;
307                 goto out_path;
308         }
309         /*
310          * Wait for connection confirmation
311          */
312         wait_event(mon_conn_wait_queue,
313                    atomic_read(&monpriv->iucv_connected) ||
314                    atomic_read(&monpriv->iucv_severed));
315         if (atomic_read(&monpriv->iucv_severed)) {
316                 atomic_set(&monpriv->iucv_severed, 0);
317                 atomic_set(&monpriv->iucv_connected, 0);
318                 rc = -EIO;
319                 goto out_path;
320         }
321         filp->private_data = monpriv;
322         unlock_kernel();
323         return nonseekable_open(inode, filp);
324
325 out_path:
326         kfree(monpriv->path);
327 out_priv:
328         mon_free_mem(monpriv);
329 out_use:
330         clear_bit(MON_IN_USE, &mon_in_use);
331 out:
332         unlock_kernel();
333         return rc;
334 }
335
336 static int mon_close(struct inode *inode, struct file *filp)
337 {
338         int rc, i;
339         struct mon_private *monpriv = filp->private_data;
340
341         /*
342          * Close IUCV connection and unregister
343          */
344         rc = iucv_path_sever(monpriv->path, user_data_sever);
345         if (rc)
346                 pr_warning("Disconnecting the z/VM *MONITOR system service "
347                            "failed with rc=%i\n", rc);
348
349         atomic_set(&monpriv->iucv_severed, 0);
350         atomic_set(&monpriv->iucv_connected, 0);
351         atomic_set(&monpriv->read_ready, 0);
352         atomic_set(&monpriv->msglim_count, 0);
353         monpriv->write_index  = 0;
354         monpriv->read_index   = 0;
355
356         for (i = 0; i < MON_MSGLIM; i++)
357                 kfree(monpriv->msg_array[i]);
358         kfree(monpriv);
359         clear_bit(MON_IN_USE, &mon_in_use);
360         return 0;
361 }
362
363 static ssize_t mon_read(struct file *filp, char __user *data,
364                         size_t count, loff_t *ppos)
365 {
366         struct mon_private *monpriv = filp->private_data;
367         struct mon_msg *monmsg;
368         int ret;
369         u32 mce_start;
370
371         monmsg = mon_next_message(monpriv);
372         if (IS_ERR(monmsg))
373                 return PTR_ERR(monmsg);
374
375         if (!monmsg) {
376                 if (filp->f_flags & O_NONBLOCK)
377                         return -EAGAIN;
378                 ret = wait_event_interruptible(mon_read_wait_queue,
379                                         atomic_read(&monpriv->read_ready) ||
380                                         atomic_read(&monpriv->iucv_severed));
381                 if (ret)
382                         return ret;
383                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
384                         return -EIO;
385                 monmsg = monpriv->msg_array[monpriv->read_index];
386         }
387
388         if (!monmsg->pos)
389                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
390         if (mon_check_mca(monmsg))
391                 goto reply;
392
393         /* read monitor control element (12 bytes) first */
394         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
395         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
396                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
397                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
398                                    count);
399                 if (ret)
400                         return -EFAULT;
401                 monmsg->pos += count;
402                 if (monmsg->pos == mce_start + 12)
403                         monmsg->pos = mon_rec_start(monmsg);
404                 goto out_copy;
405         }
406
407         /* read records */
408         if (monmsg->pos <= mon_rec_end(monmsg)) {
409                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
410                                             + 1);
411                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
412                                    count);
413                 if (ret)
414                         return -EFAULT;
415                 monmsg->pos += count;
416                 if (monmsg->pos > mon_rec_end(monmsg))
417                         mon_next_mca(monmsg);
418                 goto out_copy;
419         }
420 reply:
421         ret = mon_send_reply(monmsg, monpriv);
422         return ret;
423
424 out_copy:
425         *ppos += count;
426         return count;
427 }
428
429 static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
430 {
431         struct mon_private *monpriv = filp->private_data;
432
433         poll_wait(filp, &mon_read_wait_queue, p);
434         if (unlikely(atomic_read(&monpriv->iucv_severed)))
435                 return POLLERR;
436         if (atomic_read(&monpriv->read_ready))
437                 return POLLIN | POLLRDNORM;
438         return 0;
439 }
440
441 static const struct file_operations mon_fops = {
442         .owner   = THIS_MODULE,
443         .open    = &mon_open,
444         .release = &mon_close,
445         .read    = &mon_read,
446         .poll    = &mon_poll,
447 };
448
449 static struct miscdevice mon_dev = {
450         .name       = "monreader",
451         .fops       = &mon_fops,
452         .minor      = MISC_DYNAMIC_MINOR,
453 };
454
455 /******************************************************************************
456  *                              module init/exit                              *
457  *****************************************************************************/
458 static int __init mon_init(void)
459 {
460         int rc;
461
462         if (!MACHINE_IS_VM) {
463                 pr_err("The z/VM *MONITOR record device driver cannot be "
464                        "loaded without z/VM\n");
465                 return -ENODEV;
466         }
467
468         /*
469          * Register with IUCV and connect to *MONITOR service
470          */
471         rc = iucv_register(&monreader_iucv_handler, 1);
472         if (rc) {
473                 pr_err("The z/VM *MONITOR record device driver failed to "
474                        "register with IUCV\n");
475                 return rc;
476         }
477
478         rc = segment_type(mon_dcss_name);
479         if (rc < 0) {
480                 segment_warning(rc, mon_dcss_name);
481                 goto out_iucv;
482         }
483         if (rc != SEG_TYPE_SC) {
484                 pr_err("The specified *MONITOR DCSS %s does not have the "
485                        "required type SC\n", mon_dcss_name);
486                 rc = -EINVAL;
487                 goto out_iucv;
488         }
489
490         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
491                           &mon_dcss_start, &mon_dcss_end);
492         if (rc < 0) {
493                 segment_warning(rc, mon_dcss_name);
494                 rc = -EINVAL;
495                 goto out_iucv;
496         }
497         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
498
499         rc = misc_register(&mon_dev);
500         if (rc < 0 )
501                 goto out;
502         return 0;
503
504 out:
505         segment_unload(mon_dcss_name);
506 out_iucv:
507         iucv_unregister(&monreader_iucv_handler, 1);
508         return rc;
509 }
510
511 static void __exit mon_exit(void)
512 {
513         segment_unload(mon_dcss_name);
514         WARN_ON(misc_deregister(&mon_dev) != 0);
515         iucv_unregister(&monreader_iucv_handler, 1);
516         return;
517 }
518
519
520 module_init(mon_init);
521 module_exit(mon_exit);
522
523 module_param_string(mondcss, mon_dcss_name, 9, 0444);
524 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
525                  "service, max. 8 chars. Default is MONDCSS");
526
527 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
528 MODULE_DESCRIPTION("Character device driver for reading z/VM "
529                    "monitor service records.");
530 MODULE_LICENSE("GPL");