2 * Common data handling layer for ser_gigaset and usb_gigaset
4 * Copyright (c) 2005 by Tilman Schmidt <tilman@imap.cc>,
5 * Hansjoerg Lipp <hjlipp@web.de>,
8 * =====================================================================
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of
12 * the License, or (at your option) any later version.
13 * =====================================================================
17 #include <linux/crc-ccitt.h>
18 #include <linux/bitrev.h>
20 /* check if byte must be stuffed/escaped
21 * I'm not sure which data should be encoded.
22 * Therefore I will go the hard way and encode every value
23 * less than 0x20, the flag sequence and the control escape char.
25 static inline int muststuff(unsigned char c)
27 if (c < PPP_TRANS) return 1;
28 if (c == PPP_FLAG) return 1;
29 if (c == PPP_ESCAPE) return 1;
30 /* other possible candidates: */
31 /* 0x91: XON with parity set */
32 /* 0x93: XOFF with parity set */
36 /* == data input =========================================================== */
38 /* process a block of received bytes in command mode
39 * (mstate != MS_LOCKED && (inputstate & INS_command))
40 * Append received bytes to the command response buffer and forward them
41 * line by line to the response handler. Exit whenever a mode/state change
42 * might have occurred.
43 * Note: Received lines may be terminated by CR, LF, or CR LF, which will be
44 * removed before passing the line to the response handler.
46 * number of processed bytes
48 static unsigned cmd_loop(unsigned numbytes, struct inbuf_t *inbuf)
50 unsigned char *src = inbuf->data + inbuf->head;
51 struct cardstate *cs = inbuf->cs;
52 unsigned cbytes = cs->cbytes;
53 unsigned procbytes = 0;
56 while (procbytes < numbytes) {
62 if (cbytes == 0 && cs->respdata[0] == '\r') {
63 /* collapse LF with preceding CR */
67 /* --v-- fall through --v-- */
69 /* end of message line, pass to response handler */
70 if (cbytes >= MAX_RESP_SIZE) {
71 dev_warn(cs->dev, "response too large (%d)\n",
73 cbytes = MAX_RESP_SIZE;
76 gigaset_dbg_buffer(DEBUG_TRANSCMD, "received response",
77 cbytes, cs->respdata);
78 gigaset_handle_modem_response(cs);
81 /* store EOL byte for CRLF collapsing */
84 /* cs->dle may have changed */
85 if (cs->dle && !(inbuf->inputstate & INS_DLE_command))
86 inbuf->inputstate &= ~INS_command;
88 /* return for reevaluating state */
92 if (inbuf->inputstate & INS_DLE_char) {
93 /* quoted DLE: clear quote flag */
94 inbuf->inputstate &= ~INS_DLE_char;
96 (inbuf->inputstate & INS_DLE_command)) {
97 /* DLE escape, pass up for handling */
98 inbuf->inputstate |= INS_DLE_char;
101 /* quoted or not in DLE mode: treat as regular data */
102 /* --v-- fall through --v-- */
104 /* append to line buffer if possible */
105 if (cbytes < MAX_RESP_SIZE)
106 cs->respdata[cbytes] = c;
115 /* process a block of received bytes in lock mode
116 * All received bytes are passed unmodified to the tty i/f.
118 * number of processed bytes
120 static unsigned lock_loop(unsigned numbytes, struct inbuf_t *inbuf)
122 unsigned char *src = inbuf->data + inbuf->head;
124 gigaset_dbg_buffer(DEBUG_LOCKCMD, "received response", numbytes, src);
125 gigaset_if_receive(inbuf->cs, src, numbytes);
129 /* process a block of received bytes in HDLC data mode
130 * (mstate != MS_LOCKED && !(inputstate & INS_command) && proto2 == L2_HDLC)
131 * Collect HDLC frames, undoing byte stuffing and watching for DLE escapes.
132 * When a frame is complete, check the FCS and pass valid frames to the LL.
133 * If DLE is encountered, return immediately to let the caller handle it.
135 * number of processed bytes
137 static unsigned hdlc_loop(unsigned numbytes, struct inbuf_t *inbuf)
139 struct cardstate *cs = inbuf->cs;
140 struct bc_state *bcs = cs->bcs;
141 int inputstate = bcs->inputstate;
142 __u16 fcs = bcs->rx_fcs;
143 struct sk_buff *skb = bcs->rx_skb;
144 unsigned char *src = inbuf->data + inbuf->head;
145 unsigned procbytes = 0;
148 if (inputstate & INS_byte_stuff) {
151 inputstate &= ~INS_byte_stuff;
155 while (procbytes < numbytes) {
159 if (inputstate & INS_DLE_char) {
160 /* quoted DLE: clear quote flag */
161 inputstate &= ~INS_DLE_char;
162 } else if (cs->dle || (inputstate & INS_DLE_command)) {
163 /* DLE escape, pass up for handling */
164 inputstate |= INS_DLE_char;
169 if (c == PPP_ESCAPE) {
170 /* byte stuffing indicator: pull in next byte */
171 if (procbytes >= numbytes) {
172 /* end of buffer, save for later processing */
173 inputstate |= INS_byte_stuff;
180 if (inputstate & INS_DLE_char) {
181 /* quoted DLE: clear quote flag */
182 inputstate &= ~INS_DLE_char;
183 } else if (cs->dle ||
184 (inputstate & INS_DLE_command)) {
185 /* DLE escape, pass up for handling */
187 INS_DLE_char | INS_byte_stuff;
192 #ifdef CONFIG_GIGASET_DEBUG
194 gig_dbg(DEBUG_HDLC, "byte stuffed: 0x%02x", c);
196 } else if (c == PPP_FLAG) {
197 /* end of frame: process content if any */
198 if (inputstate & INS_have_data) {
200 "7e----------------------------");
202 /* check and pass received frame */
205 gigaset_isdn_rcv_err(bcs);
206 } else if (skb->len < 2) {
207 /* frame too short for FCS */
209 "short frame (%d)\n",
211 gigaset_isdn_rcv_err(bcs);
212 dev_kfree_skb_any(skb);
213 } else if (fcs != PPP_GOODFCS) {
214 /* frame check error */
216 "Checksum failed, %u bytes corrupted!\n",
218 gigaset_isdn_rcv_err(bcs);
219 dev_kfree_skb_any(skb);
222 __skb_trim(skb, skb->len - 2);
223 gigaset_skb_rcvd(bcs, skb);
226 /* prepare reception of next frame */
227 inputstate &= ~INS_have_data;
228 skb = gigaset_new_rx_skb(bcs);
230 /* empty frame (7E 7E) */
231 #ifdef CONFIG_GIGASET_DEBUG
236 gigaset_isdn_rcv_err(bcs);
237 skb = gigaset_new_rx_skb(bcs);
243 #ifdef CONFIG_GIGASET_DEBUG
244 } else if (muststuff(c)) {
245 /* Should not happen. Possible after ZDLE=1<CR><LF>. */
246 gig_dbg(DEBUG_HDLC, "not byte stuffed: 0x%02x", c);
250 /* regular data byte, append to skb */
251 #ifdef CONFIG_GIGASET_DEBUG
252 if (!(inputstate & INS_have_data)) {
253 gig_dbg(DEBUG_HDLC, "7e (%d x) ================",
258 inputstate |= INS_have_data;
260 if (skb->len >= bcs->rx_bufsize) {
261 dev_warn(cs->dev, "received packet too long\n");
262 dev_kfree_skb_any(skb);
263 /* skip remainder of packet */
264 bcs->rx_skb = skb = NULL;
266 *__skb_put(skb, 1) = c;
267 fcs = crc_ccitt_byte(fcs, c);
272 bcs->inputstate = inputstate;
277 /* process a block of received bytes in transparent data mode
278 * (mstate != MS_LOCKED && !(inputstate & INS_command) && proto2 != L2_HDLC)
279 * Invert bytes, undoing byte stuffing and watching for DLE escapes.
280 * If DLE is encountered, return immediately to let the caller handle it.
282 * number of processed bytes
284 static unsigned iraw_loop(unsigned numbytes, struct inbuf_t *inbuf)
286 struct cardstate *cs = inbuf->cs;
287 struct bc_state *bcs = cs->bcs;
288 int inputstate = bcs->inputstate;
289 struct sk_buff *skb = bcs->rx_skb;
290 unsigned char *src = inbuf->data + inbuf->head;
291 unsigned procbytes = 0;
295 /* skip this block */
296 gigaset_new_rx_skb(bcs);
300 while (procbytes < numbytes && skb->len < bcs->rx_bufsize) {
305 if (inputstate & INS_DLE_char) {
306 /* quoted DLE: clear quote flag */
307 inputstate &= ~INS_DLE_char;
308 } else if (cs->dle || (inputstate & INS_DLE_command)) {
309 /* DLE escape, pass up for handling */
310 inputstate |= INS_DLE_char;
315 /* regular data byte: append to current skb */
316 inputstate |= INS_have_data;
317 *__skb_put(skb, 1) = bitrev8(c);
321 if (inputstate & INS_have_data) {
322 gigaset_skb_rcvd(bcs, skb);
323 inputstate &= ~INS_have_data;
324 gigaset_new_rx_skb(bcs);
327 bcs->inputstate = inputstate;
331 /* process DLE escapes
332 * Called whenever a DLE sequence might be encountered in the input stream.
333 * Either processes the entire DLE sequence or, if that isn't possible,
334 * notes the fact that an initial DLE has been received in the INS_DLE_char
335 * inputstate flag and resumes processing of the sequence on the next call.
337 static void handle_dle(struct inbuf_t *inbuf)
339 struct cardstate *cs = inbuf->cs;
341 if (cs->mstate == MS_LOCKED)
342 return; /* no DLE processing in lock mode */
344 if (!(inbuf->inputstate & INS_DLE_char)) {
346 if (inbuf->data[inbuf->head] == DLE_FLAG &&
347 (cs->dle || inbuf->inputstate & INS_DLE_command)) {
348 /* start of DLE sequence */
350 if (inbuf->head == inbuf->tail ||
351 inbuf->head == RBUFSIZE) {
352 /* end of buffer, save for later processing */
353 inbuf->inputstate |= INS_DLE_char;
357 /* regular data byte */
362 /* consume pending DLE */
363 inbuf->inputstate &= ~INS_DLE_char;
365 switch (inbuf->data[inbuf->head]) {
366 case 'X': /* begin of event message */
367 if (inbuf->inputstate & INS_command)
369 "received <DLE>X in command mode\n");
370 inbuf->inputstate |= INS_command | INS_DLE_command;
371 inbuf->head++; /* byte consumed */
373 case '.': /* end of event message */
374 if (!(inbuf->inputstate & INS_DLE_command))
376 "received <DLE>. without <DLE>X\n");
377 inbuf->inputstate &= ~INS_DLE_command;
378 /* return to data mode if in DLE mode */
380 inbuf->inputstate &= ~INS_command;
381 inbuf->head++; /* byte consumed */
383 case DLE_FLAG: /* DLE in data stream */
385 inbuf->inputstate |= INS_DLE_char;
386 if (!(cs->dle || inbuf->inputstate & INS_DLE_command))
388 "received <DLE><DLE> not in DLE mode\n");
389 break; /* quoted byte left in buffer */
391 dev_notice(cs->dev, "received <DLE><%02x>\n",
392 inbuf->data[inbuf->head]);
393 /* quoted byte left in buffer */
398 * gigaset_m10x_input() - process a block of data received from the device
399 * @inbuf: received data and device descriptor structure.
401 * Called by hardware module {ser,usb}_gigaset with a block of received
402 * bytes. Separates the bytes received over the serial data channel into
403 * user data and command replies (locked/unlocked) according to the
404 * current state of the interface.
406 void gigaset_m10x_input(struct inbuf_t *inbuf)
408 struct cardstate *cs = inbuf->cs;
409 unsigned numbytes, procbytes;
411 gig_dbg(DEBUG_INTR, "buffer state: %u -> %u", inbuf->head, inbuf->tail);
413 while (inbuf->head != inbuf->tail) {
414 /* check for DLE escape */
417 /* process a contiguous block of bytes */
418 numbytes = (inbuf->head > inbuf->tail ?
419 RBUFSIZE : inbuf->tail) - inbuf->head;
420 gig_dbg(DEBUG_INTR, "processing %u bytes", numbytes);
422 * numbytes may be 0 if handle_dle() ate the last byte.
423 * This does no harm, *_loop() will just return 0 immediately.
426 if (cs->mstate == MS_LOCKED)
427 procbytes = lock_loop(numbytes, inbuf);
428 else if (inbuf->inputstate & INS_command)
429 procbytes = cmd_loop(numbytes, inbuf);
430 else if (cs->bcs->proto2 == L2_HDLC)
431 procbytes = hdlc_loop(numbytes, inbuf);
433 procbytes = iraw_loop(numbytes, inbuf);
434 inbuf->head += procbytes;
436 /* check for buffer wraparound */
437 if (inbuf->head >= RBUFSIZE)
440 gig_dbg(DEBUG_INTR, "head set to %u", inbuf->head);
443 EXPORT_SYMBOL_GPL(gigaset_m10x_input);
446 /* == data output ========================================================== */
449 * Encode a data packet into an octet stuffed HDLC frame with FCS,
450 * opening and closing flags, preserving headroom data.
452 * skb skb containing original packet (freed upon return)
454 * pointer to newly allocated skb containing the result frame
455 * and the original link layer header, NULL on error
457 static struct sk_buff *HDLC_Encode(struct sk_buff *skb)
459 struct sk_buff *hdlc_skb;
464 unsigned int stuf_cnt;
473 fcs = crc_ccitt_byte(fcs, *cp++);
475 fcs ^= 0xffff; /* complement */
477 /* size of new buffer: original size + number of stuffing bytes
478 * + 2 bytes FCS + 2 stuffing bytes for FCS (if needed) + 2 flag bytes
479 * + room for link layer header
481 hdlc_skb = dev_alloc_skb(skb->len + stuf_cnt + 6 + skb->mac_len);
483 dev_kfree_skb_any(skb);
487 /* Copy link layer header into new skb */
488 skb_reset_mac_header(hdlc_skb);
489 skb_reserve(hdlc_skb, skb->mac_len);
490 memcpy(skb_mac_header(hdlc_skb), skb_mac_header(skb), skb->mac_len);
491 hdlc_skb->mac_len = skb->mac_len;
493 /* Add flag sequence in front of everything.. */
494 *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
496 /* Perform byte stuffing while copying data. */
498 if (muststuff(*skb->data)) {
499 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
500 *(skb_put(hdlc_skb, 1)) = (*skb->data++) ^ PPP_TRANS;
502 *(skb_put(hdlc_skb, 1)) = *skb->data++;
505 /* Finally add FCS (byte stuffed) and flag sequence */
506 c = (fcs & 0x00ff); /* least significant byte first */
508 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
511 *(skb_put(hdlc_skb, 1)) = c;
513 c = ((fcs >> 8) & 0x00ff);
515 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
518 *(skb_put(hdlc_skb, 1)) = c;
520 *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
522 dev_kfree_skb_any(skb);
527 * Encode a data packet into an octet stuffed raw bit inverted frame,
528 * preserving headroom data.
530 * skb skb containing original packet (freed upon return)
532 * pointer to newly allocated skb containing the result frame
533 * and the original link layer header, NULL on error
535 static struct sk_buff *iraw_encode(struct sk_buff *skb)
537 struct sk_buff *iraw_skb;
542 /* size of new buffer (worst case = every byte must be stuffed):
543 * 2 * original size + room for link layer header
545 iraw_skb = dev_alloc_skb(2*skb->len + skb->mac_len);
547 dev_kfree_skb_any(skb);
551 /* copy link layer header into new skb */
552 skb_reset_mac_header(iraw_skb);
553 skb_reserve(iraw_skb, skb->mac_len);
554 memcpy(skb_mac_header(iraw_skb), skb_mac_header(skb), skb->mac_len);
555 iraw_skb->mac_len = skb->mac_len;
557 /* copy and stuff data */
563 *(skb_put(iraw_skb, 1)) = c;
564 *(skb_put(iraw_skb, 1)) = c;
566 dev_kfree_skb_any(skb);
571 * gigaset_m10x_send_skb() - queue an skb for sending
572 * @bcs: B channel descriptor structure.
573 * @skb: data to send.
575 * Called by LL to encode and queue an skb for sending, and start
576 * transmission if necessary.
577 * Once the payload data has been transmitted completely, gigaset_skb_sent()
578 * will be called with the skb's link layer header preserved.
581 * number of bytes accepted for sending (skb->len) if ok,
582 * error code < 0 (eg. -ENOMEM) on error
584 int gigaset_m10x_send_skb(struct bc_state *bcs, struct sk_buff *skb)
586 struct cardstate *cs = bcs->cs;
587 unsigned len = skb->len;
590 if (bcs->proto2 == L2_HDLC)
591 skb = HDLC_Encode(skb);
593 skb = iraw_encode(skb);
596 "unable to allocate memory for encoding!\n");
600 skb_queue_tail(&bcs->squeue, skb);
601 spin_lock_irqsave(&cs->lock, flags);
603 tasklet_schedule(&cs->write_tasklet);
604 spin_unlock_irqrestore(&cs->lock, flags);
606 return len; /* ok so far */
608 EXPORT_SYMBOL_GPL(gigaset_m10x_send_skb);