Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 /*
  2  * AIRcable USB Bluetooth Dongle Driver.
  3  *
  4  * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com)
  5  * This program is free software; you can redistribute it and/or modify it under
  6  * the terms of the GNU General Public License version 2 as published by the
  7  * Free Software Foundation.
  8  *
  9  * The device works as an standard CDC device, it has 2 interfaces, the first
 10  * one is for firmware access and the second is the serial one.
 11  * The protocol is very simply, there are two posibilities reading or writing.
 12  * When writing the first urb must have a Header that starts with 0x20 0x29 the
 13  * next two bytes must say how much data will be sended.
 14  * When reading the process is almost equal except that the header starts with
 15  * 0x00 0x20.
 16  *
 17  * The device simply need some stuff to understand data comming from the usb
 18  * buffer: The First and Second byte is used for a Header, the Third and Fourth
 19  * tells the  device the amount of information the package holds.
 20  * Packages are 60 bytes long Header Stuff.
 21  * When writing to the device the first two bytes of the header are 0x20 0x29
 22  * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange
 23  * situation, when too much data arrives to the device because it sends the data
 24  * but with out the header. I will use a simply hack to override this situation,
 25  * if there is data coming that does not contain any header, then that is data
 26  * that must go directly to the tty, as there is no documentation about if there
 27  * is any other control code, I will simply check for the first
 28  * one.
 29  *
 30  * The driver registers himself with the USB-serial core and the USB Core. I had
 31  * to implement a probe function agains USB-serial, because other way, the
 32  * driver was attaching himself to both interfaces. I have tryed with different
 33  * configurations of usb_serial_driver with out exit, only the probe function
 34  * could handle this correctly.
 35  *
 36  * I have taken some info from a Greg Kroah-Hartman article:
 37  * http://www.linuxjournal.com/article/6573
 38  * And from Linux Device Driver Kit CD, which is a great work, the authors taken
 39  * the work to recompile lots of information an knowladge in drivers development
 40  * and made it all avaible inside a cd.
 41  * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/
 42  *
 43  */
 44 
 45 #include <linux/tty.h>
 46 #include <linux/tty_flip.h>
 47 #include <linux/circ_buf.h>
 48 #include <linux/usb.h>
 49 #include <linux/usb/serial.h>
 50 
 51 static int debug;
 52 
 53 /* Vendor and Product ID */
 54 #define AIRCABLE_VID            0x16CA
 55 #define AIRCABLE_USB_PID        0x1502
 56 
 57 /* write buffer size defines */
 58 #define AIRCABLE_BUF_SIZE       2048
 59 
 60 /* Protocol Stuff */
 61 #define HCI_HEADER_LENGTH       0x4
 62 #define TX_HEADER_0             0x20
 63 #define TX_HEADER_1             0x29
 64 #define RX_HEADER_0             0x00
 65 #define RX_HEADER_1             0x20
 66 #define MAX_HCI_FRAMESIZE       60
 67 #define HCI_COMPLETE_FRAME      64
 68 
 69 /* rx_flags */
 70 #define THROTTLED               0x01
 71 #define ACTUALLY_THROTTLED      0x02
 72 
 73 /*
 74  * Version Information
 75  */
 76 #define DRIVER_VERSION "v1.0b2"
 77 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>"
 78 #define DRIVER_DESC "AIRcable USB Driver"
 79 
 80 /* ID table that will be registered with USB core */
 81 static struct usb_device_id id_table [] = {
 82         { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
 83         { },
 84 };
 85 MODULE_DEVICE_TABLE(usb, id_table);
 86 
 87 
 88 /* Internal Structure */
 89 struct aircable_private {
 90         spinlock_t rx_lock;             /* spinlock for the receive lines */
 91         struct circ_buf *tx_buf;        /* write buffer */
 92         struct circ_buf *rx_buf;        /* read buffer */
 93         int rx_flags;                   /* for throttilng */
 94         struct work_struct rx_work;     /* work cue for the receiving line */
 95         struct usb_serial_port *port;   /* USB port with which associated */
 96 };
 97 
 98 /* Private methods */
 99 
100 /* Circular Buffer Methods, code from ti_usb_3410_5052 used */
101 /*
102  * serial_buf_clear
103  *
104  * Clear out all data in the circular buffer.
105  */
106 static void serial_buf_clear(struct circ_buf *cb)
107 {
108         cb->head = cb->tail = 0;
109 }
110 
111 /*
112  * serial_buf_alloc
113  *
114  * Allocate a circular buffer and all associated memory.
115  */
116 static struct circ_buf *serial_buf_alloc(void)
117 {
118         struct circ_buf *cb;
119         cb = kmalloc(sizeof(struct circ_buf), GFP_KERNEL);
120         if (cb == NULL)
121                 return NULL;
122         cb->buf = kmalloc(AIRCABLE_BUF_SIZE, GFP_KERNEL);
123         if (cb->buf == NULL) {
124                 kfree(cb);
125                 return NULL;
126         }
127         serial_buf_clear(cb);
128         return cb;
129 }
130 
131 /*
132  * serial_buf_free
133  *
134  * Free the buffer and all associated memory.
135  */
136 static void serial_buf_free(struct circ_buf *cb)
137 {
138         kfree(cb->buf);
139         kfree(cb);
140 }
141 
142 /*
143  * serial_buf_data_avail
144  *
145  * Return the number of bytes of data available in the circular
146  * buffer.
147  */
148 static int serial_buf_data_avail(struct circ_buf *cb)
149 {
150         return CIRC_CNT(cb->head,cb->tail,AIRCABLE_BUF_SIZE);
151 }
152 
153 /*
154  * serial_buf_put
155  *
156  * Copy data data from a user buffer and put it into the circular buffer.
157  * Restrict to the amount of space available.
158  *
159  * Return the number of bytes copied.
160  */
161 static int serial_buf_put(struct circ_buf *cb, const char *buf, int count)
162 {
163         int c, ret = 0;
164         while (1) {
165                 c = CIRC_SPACE_TO_END(cb->head, cb->tail, AIRCABLE_BUF_SIZE);
166                 if (count < c)
167                         c = count;
168                 if (c <= 0)
169                         break;
170                 memcpy(cb->buf + cb->head, buf, c);
171                 cb->head = (cb->head + c) & (AIRCABLE_BUF_SIZE-1);
172                 buf += c;
173                 count -= c;
174                 ret= c;
175         }
176         return ret;
177 }
178 
179 /*
180  * serial_buf_get
181  *
182  * Get data from the circular buffer and copy to the given buffer.
183  * Restrict to the amount of data available.
184  *
185  * Return the number of bytes copied.
186  */
187 static int serial_buf_get(struct circ_buf *cb, char *buf, int count)
188 {
189         int c, ret = 0;
190         while (1) {
191                 c = CIRC_CNT_TO_END(cb->head, cb->tail, AIRCABLE_BUF_SIZE);
192                 if (count < c)
193                         c = count;
194                 if (c <= 0)
195                         break;
196                 memcpy(buf, cb->buf + cb->tail, c);
197                 cb->tail = (cb->tail + c) & (AIRCABLE_BUF_SIZE-1);
198                 buf += c;
199                 count -= c;
200                 ret= c;
201         }
202         return ret;
203 }
204 
205 /* End of circula buffer methods */
206 
207 static void aircable_send(struct usb_serial_port *port)
208 {
209         int count, result;
210         struct aircable_private *priv = usb_get_serial_port_data(port);
211         unsigned char* buf;
212         u16 *dbuf;
213         dbg("%s - port %d", __FUNCTION__, port->number);
214         if (port->write_urb_busy)
215                 return;
216 
217         count = min(serial_buf_data_avail(priv->tx_buf), MAX_HCI_FRAMESIZE);
218         if (count == 0)
219                 return;
220 
221         buf = kzalloc(count + HCI_HEADER_LENGTH, GFP_ATOMIC);
222         if (!buf) {
223                 err("%s- kzalloc(%d) failed.", __FUNCTION__,
224                     count + HCI_HEADER_LENGTH);
225                 return;
226         }
227 
228         buf[0] = TX_HEADER_0;
229         buf[1] = TX_HEADER_1;
230         dbuf = (u16 *)&buf[2];
231         *dbuf = cpu_to_le16((u16)count);
232         serial_buf_get(priv->tx_buf,buf + HCI_HEADER_LENGTH, MAX_HCI_FRAMESIZE);
233 
234         memcpy(port->write_urb->transfer_buffer, buf,
235                count + HCI_HEADER_LENGTH);
236 
237         kfree(buf);
238         port->write_urb_busy = 1;
239         usb_serial_debug_data(debug, &port->dev, __FUNCTION__,
240                               count + HCI_HEADER_LENGTH,
241                               port->write_urb->transfer_buffer);
242         port->write_urb->transfer_buffer_length = count + HCI_HEADER_LENGTH;
243         port->write_urb->dev = port->serial->dev;
244         result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
245 
246         if (result) {
247                 dev_err(&port->dev,
248                         "%s - failed submitting write urb, error %d\n",
249                         __FUNCTION__, result);
250                 port->write_urb_busy = 0;
251         }
252 
253         schedule_work(&port->work);
254 }
255 
256 static void aircable_read(struct work_struct *work)
257 {
258         struct aircable_private *priv =
259                 container_of(work, struct aircable_private, rx_work);
260         struct usb_serial_port *port = priv->port;
261         struct tty_struct *tty;
262         unsigned char *data;
263         int count;
264         if (priv->rx_flags & THROTTLED){
265                 if (priv->rx_flags & ACTUALLY_THROTTLED)
266                         schedule_work(&priv->rx_work);
267                 return;
268         }
269 
270         /* By now I will flush data to the tty in packages of no more than
271          * 64 bytes, to ensure I do not get throttled.
272          * Ask USB mailing list for better aproach.
273          */
274         tty = port->tty;
275 
276         if (!tty) {
277                 schedule_work(&priv->rx_work);
278                 err("%s - No tty available", __FUNCTION__);
279                 return ;
280         }
281 
282         count = min(64, serial_buf_data_avail(priv->rx_buf));
283 
284         if (count <= 0)
285                 return; //We have finished sending everything.
286 
287         tty_prepare_flip_string(tty, &data, count);
288         if (!data){
289                 err("%s- kzalloc(%d) failed.", __FUNCTION__, count);
290                 return;
291         }
292 
293         serial_buf_get(priv->rx_buf, data, count);
294 
295         tty_flip_buffer_push(tty);
296 
297         if (serial_buf_data_avail(priv->rx_buf))
298                 schedule_work(&priv->rx_work);
299 
300         return;
301 }
302 /* End of private methods */
303 
304 static int aircable_probe(struct usb_serial *serial,
305                           const struct usb_device_id *id)
306 {
307         struct usb_host_interface *iface_desc = serial->interface->cur_altsetting;
308         struct usb_endpoint_descriptor *endpoint;
309         int num_bulk_out=0;
310         int i;
311 
312         for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
313                 endpoint = &iface_desc->endpoint[i].desc;
314                 if (usb_endpoint_is_bulk_out(endpoint)) {
315                         dbg("found bulk out on endpoint %d", i);
316                         ++num_bulk_out;
317                 }
318         }
319 
320         if (num_bulk_out == 0) {
321                 dbg("Invalid interface, discarding");
322                 return -ENODEV;
323         }
324 
325         return 0;
326 }
327 
328 static int aircable_attach (struct usb_serial *serial)
329 {
330         struct usb_serial_port *port = serial->port[0];
331         struct aircable_private *priv;
332 
333         priv = kzalloc(sizeof(struct aircable_private), GFP_KERNEL);
334         if (!priv){
335                 err("%s- kmalloc(%Zd) failed.", __FUNCTION__,
336                         sizeof(struct aircable_private));
337                 return -ENOMEM;
338         }
339 
340         /* Allocation of Circular Buffers */
341         priv->tx_buf = serial_buf_alloc();
342         if (priv->tx_buf == NULL) {
343                 kfree(priv);
344                 return -ENOMEM;
345         }
346 
347         priv->rx_buf = serial_buf_alloc();
348         if (priv->rx_buf == NULL) {
349                 kfree(priv->tx_buf);
350                 kfree(priv);
351                 return -ENOMEM;
352         }
353 
354         priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
355         priv->port = port;
356         INIT_WORK(&priv->rx_work, aircable_read);
357 
358         usb_set_serial_port_data(serial->port[0], priv);
359 
360         return 0;
361 }
362 
363 static void aircable_shutdown(struct usb_serial *serial)
364 {
365 
366         struct usb_serial_port *port = serial->port[0];
367         struct aircable_private *priv = usb_get_serial_port_data(port);
368 
369         dbg("%s", __FUNCTION__);
370 
371         if (priv) {
372                 serial_buf_free(priv->tx_buf);
373                 serial_buf_free(priv->rx_buf);
374                 usb_set_serial_port_data(port, NULL);
375                 kfree(priv);
376         }
377 }
378 
379 static int aircable_write_room(struct usb_serial_port *port)
380 {
381         struct aircable_private *priv = usb_get_serial_port_data(port);
382         return serial_buf_data_avail(priv->tx_buf);
383 }
384 
385 static int aircable_write(struct usb_serial_port *port,
386                           const unsigned char *source, int count)
387 {
388         struct aircable_private *priv = usb_get_serial_port_data(port);
389         int temp;
390 
391         dbg("%s - port %d, %d bytes", __FUNCTION__, port->number, count);
392 
393         usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, source);
394 
395         if (!count){
396                 dbg("%s - write request of 0 bytes", __FUNCTION__);
397                 return count;
398         }
399 
400         temp = serial_buf_put(priv->tx_buf, source, count);
401 
402         aircable_send(port);
403 
404         if (count > AIRCABLE_BUF_SIZE)
405                 count = AIRCABLE_BUF_SIZE;
406 
407         return count;
408 
409 }
410 
411 static void aircable_write_bulk_callback(struct urb *urb)
412 {
413         struct usb_serial_port *port = urb->context;
414         int status = urb->status;
415         int result;
416 
417         dbg("%s - urb status: %d", __FUNCTION__ , status);
418 
419         /* This has been taken from cypress_m8.c cypress_write_int_callback */
420         switch (status) {
421                 case 0:
422                         /* success */
423                         break;
424                 case -ECONNRESET:
425                 case -ENOENT:
426                 case -ESHUTDOWN:
427                         /* this urb is terminated, clean up */
428                         dbg("%s - urb shutting down with status: %d",
429                             __FUNCTION__, status);
430                         port->write_urb_busy = 0;
431                         return;
432                 default:
433                         /* error in the urb, so we have to resubmit it */
434                         dbg("%s - Overflow in write", __FUNCTION__);
435                         dbg("%s - nonzero write bulk status received: %d",
436                             __FUNCTION__, status);
437                         port->write_urb->transfer_buffer_length = 1;
438                         port->write_urb->dev = port->serial->dev;
439                         result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
440                         if (result)
441                                 dev_err(&urb->dev->dev,
442                                         "%s - failed resubmitting write urb, error %d\n",
443                                         __FUNCTION__, result);
444                         else
445                                 return;
446         }
447 
448         port->write_urb_busy = 0;
449 
450         aircable_send(port);
451 }
452 
453 static void aircable_read_bulk_callback(struct urb *urb)
454 {
455         struct usb_serial_port *port = urb->context;
456         struct aircable_private *priv = usb_get_serial_port_data(port);
457         struct tty_struct *tty;
458         unsigned long no_packages, remaining, package_length, i;
459         int result, shift = 0;
460         unsigned char *temp;
461         int status = urb->status;
462 
463         dbg("%s - port %d", __FUNCTION__, port->number);
464 
465         if (status) {
466                 dbg("%s - urb status = %d", __FUNCTION__, status);
467                 if (!port->open_count) {
468                         dbg("%s - port is closed, exiting.", __FUNCTION__);
469                         return;
470                 }
471                 if (status == -EPROTO) {
472                         dbg("%s - caught -EPROTO, resubmitting the urb",
473                             __FUNCTION__);
474                         usb_fill_bulk_urb(port->read_urb, port->serial->dev,
475                                           usb_rcvbulkpipe(port->serial->dev,
476                                                           port->bulk_in_endpointAddress),
477                                           port->read_urb->transfer_buffer,
478                                           port->read_urb->transfer_buffer_length,
479                                           aircable_read_bulk_callback, port);
480 
481                         result = usb_submit_urb(urb, GFP_ATOMIC);
482                         if (result)
483                                 dev_err(&urb->dev->dev,
484                                         "%s - failed resubmitting read urb, error %d\n",
485                                         __FUNCTION__, result);
486                         return;
487                 }
488                 dbg("%s - unable to handle the error, exiting.", __FUNCTION__);
489                 return;
490         }
491 
492         usb_serial_debug_data(debug, &port->dev, __FUNCTION__,
493                                 urb->actual_length,urb->transfer_buffer);
494 
495         tty = port->tty;
496         if (tty && urb->actual_length) {
497                 if (urb->actual_length <= 2) {
498                         /* This is an incomplete package */
499                         serial_buf_put(priv->rx_buf, urb->transfer_buffer,
500                                        urb->actual_length);
501                 } else {
502                         temp = urb->transfer_buffer;
503                         if (temp[0] == RX_HEADER_0)
504                                 shift = HCI_HEADER_LENGTH;
505 
506                         remaining = urb->actual_length;
507                         no_packages = urb->actual_length / (HCI_COMPLETE_FRAME);
508 
509                         if (urb->actual_length % HCI_COMPLETE_FRAME != 0)
510                                 no_packages+=1;
511 
512                         for (i = 0; i < no_packages ;i++) {
513                                 if (remaining > (HCI_COMPLETE_FRAME))
514                                         package_length = HCI_COMPLETE_FRAME;
515                                 else
516                                         package_length = remaining;
517                                 remaining -= package_length;
518 
519                                 serial_buf_put(priv->rx_buf,
520                                         urb->transfer_buffer + shift +
521                                         (HCI_COMPLETE_FRAME) * (i),
522                                         package_length - shift);
523                         }
524                 }
525                 aircable_read(&priv->rx_work);
526         }
527 
528         /* Schedule the next read _if_ we are still open */
529         if (port->open_count) {
530                 usb_fill_bulk_urb(port->read_urb, port->serial->dev,
531                                   usb_rcvbulkpipe(port->serial->dev,
532                                                   port->bulk_in_endpointAddress),
533                                   port->read_urb->transfer_buffer,
534                                   port->read_urb->transfer_buffer_length,
535                                   aircable_read_bulk_callback, port);
536 
537                 result = usb_submit_urb(urb, GFP_ATOMIC);
538                 if (result)
539                         dev_err(&urb->dev->dev,
540                                 "%s - failed resubmitting read urb, error %d\n",
541                                 __FUNCTION__, result);
542         }
543 
544         return;
545 }
546 
547 /* Based on ftdi_sio.c throttle */
548 static void aircable_throttle(struct usb_serial_port *port)
549 {
550         struct aircable_private *priv = usb_get_serial_port_data(port);
551         unsigned long flags;
552 
553         dbg("%s - port %d", __FUNCTION__, port->number);
554 
555         spin_lock_irqsave(&priv->rx_lock, flags);
556         priv->rx_flags |= THROTTLED;
557         spin_unlock_irqrestore(&priv->rx_lock, flags);
558 }
559 
560 /* Based on ftdi_sio.c unthrottle */
561 static void aircable_unthrottle(struct usb_serial_port *port)
562 {
563         struct aircable_private *priv = usb_get_serial_port_data(port);
564         int actually_throttled;
565         unsigned long flags;
566 
567         dbg("%s - port %d", __FUNCTION__, port->number);
568 
569         spin_lock_irqsave(&priv->rx_lock, flags);
570         actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
571         priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
572         spin_unlock_irqrestore(&priv->rx_lock, flags);
573 
574         if (actually_throttled)
575                 schedule_work(&priv->rx_work);
576 }
577 
578 static struct usb_driver aircable_driver = {
579         .name =         "aircable",
580         .probe =        usb_serial_probe,
581         .disconnect =   usb_serial_disconnect,
582         .id_table =     id_table,
583         .no_dynamic_id =        1,
584 };
585 
586 static struct usb_serial_driver aircable_device = {
587         .driver = {
588                 .owner =        THIS_MODULE,
589                 .name =         "aircable",
590         },
591         .usb_driver =           &aircable_driver,
592         .id_table =             id_table,
593         .num_ports =            1,
594         .attach =               aircable_attach,
595         .probe =                aircable_probe,
596         .shutdown =             aircable_shutdown,
597         .write =                aircable_write,
598         .write_room =           aircable_write_room,
599         .write_bulk_callback =  aircable_write_bulk_callback,
600         .read_bulk_callback =   aircable_read_bulk_callback,
601         .throttle =             aircable_throttle,
602         .unthrottle =           aircable_unthrottle,
603 };
604 
605 static int __init aircable_init (void)
606 {
607         int retval;
608         retval = usb_serial_register(&aircable_device);
609         if (retval)
610                 goto failed_serial_register;
611         retval = usb_register(&aircable_driver);
612         if (retval)
613                 goto failed_usb_register;
614         return 0;
615 
616 failed_serial_register:
617         usb_serial_deregister(&aircable_device);
618 failed_usb_register:
619         return retval;
620 }
621 
622 static void __exit aircable_exit (void)
623 {
624         usb_deregister(&aircable_driver);
625         usb_serial_deregister(&aircable_device);
626 }
627 
628 MODULE_AUTHOR(DRIVER_AUTHOR);
629 MODULE_DESCRIPTION(DRIVER_DESC);
630 MODULE_VERSION(DRIVER_VERSION);
631 MODULE_LICENSE("GPL");
632 
633 module_init(aircable_init);
634 module_exit(aircable_exit);
635 
636 module_param(debug, bool, S_IRUGO | S_IWUSR);
637 MODULE_PARM_DESC(debug, "Debug enabled or not");
638 
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