xref: /openbmc/linux/drivers/usb/host/fhci-tds.c (revision ab73b751)
1 /*
2  * Freescale QUICC Engine USB Host Controller Driver
3  *
4  * Copyright (c) Freescale Semicondutor, Inc. 2006.
5  *               Shlomi Gridish <gridish@freescale.com>
6  *               Jerry Huang <Chang-Ming.Huang@freescale.com>
7  * Copyright (c) Logic Product Development, Inc. 2007
8  *               Peter Barada <peterb@logicpd.com>
9  * Copyright (c) MontaVista Software, Inc. 2008.
10  *               Anton Vorontsov <avorontsov@ru.mvista.com>
11  *
12  * This program is free software; you can redistribute  it and/or modify it
13  * under  the terms of  the GNU General  Public License as published by the
14  * Free Software Foundation;  either version 2 of the  License, or (at your
15  * option) any later version.
16  */
17 
18 #include <linux/kernel.h>
19 #include <linux/types.h>
20 #include <linux/errno.h>
21 #include <linux/slab.h>
22 #include <linux/list.h>
23 #include <linux/io.h>
24 #include <linux/usb.h>
25 #include <linux/usb/hcd.h>
26 #include "fhci.h"
27 
28 #define DUMMY_BD_BUFFER  0xdeadbeef
29 #define DUMMY2_BD_BUFFER 0xbaadf00d
30 
31 /* Transaction Descriptors bits */
32 #define TD_R		0x8000 /* ready bit */
33 #define TD_W		0x2000 /* wrap bit */
34 #define TD_I		0x1000 /* interrupt on completion */
35 #define TD_L		0x0800 /* last */
36 #define TD_TC		0x0400 /* transmit CRC */
37 #define TD_CNF		0x0200 /* CNF - Must be always 1 */
38 #define TD_LSP		0x0100 /* Low-speed transaction */
39 #define TD_PID		0x00c0 /* packet id */
40 #define TD_RXER		0x0020 /* Rx error or not */
41 
42 #define TD_NAK		0x0010 /* No ack. */
43 #define TD_STAL		0x0008 /* Stall received */
44 #define TD_TO		0x0004 /* time out */
45 #define TD_UN		0x0002 /* underrun */
46 #define TD_NO		0x0010 /* Rx Non Octet Aligned Packet */
47 #define TD_AB		0x0008 /* Frame Aborted */
48 #define TD_CR		0x0004 /* CRC Error */
49 #define TD_OV		0x0002 /* Overrun */
50 #define TD_BOV		0x0001 /* Buffer Overrun */
51 
52 #define TD_ERRORS	(TD_NAK | TD_STAL | TD_TO | TD_UN | \
53 			 TD_NO | TD_AB | TD_CR | TD_OV | TD_BOV)
54 
55 #define TD_PID_DATA0	0x0080 /* Data 0 toggle */
56 #define TD_PID_DATA1	0x00c0 /* Data 1 toggle */
57 #define TD_PID_TOGGLE	0x00c0 /* Data 0/1 toggle mask */
58 
59 #define TD_TOK_SETUP	0x0000
60 #define TD_TOK_OUT	0x4000
61 #define TD_TOK_IN	0x8000
62 #define TD_ISO		0x1000
63 #define TD_ENDP		0x0780
64 #define TD_ADDR		0x007f
65 
66 #define TD_ENDP_SHIFT 7
67 
68 struct usb_td {
69 	__be16 status;
70 	__be16 length;
71 	__be32 buf_ptr;
72 	__be16 extra;
73 	__be16 reserved;
74 };
75 
76 static struct usb_td __iomem *next_bd(struct usb_td __iomem *base,
77 				      struct usb_td __iomem *td,
78 				      u16 status)
79 {
80 	if (status & TD_W)
81 		return base;
82 	else
83 		return ++td;
84 }
85 
86 void fhci_push_dummy_bd(struct endpoint *ep)
87 {
88 	if (ep->already_pushed_dummy_bd == false) {
89 		u16 td_status = in_be16(&ep->empty_td->status);
90 
91 		out_be32(&ep->empty_td->buf_ptr, DUMMY_BD_BUFFER);
92 		/* get the next TD in the ring */
93 		ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
94 		ep->already_pushed_dummy_bd = true;
95 	}
96 }
97 
98 /* destroy an USB endpoint */
99 void fhci_ep0_free(struct fhci_usb *usb)
100 {
101 	struct endpoint *ep;
102 	int size;
103 
104 	ep = usb->ep0;
105 	if (ep) {
106 		if (ep->td_base)
107 			cpm_muram_free(cpm_muram_offset(ep->td_base));
108 
109 		if (kfifo_initialized(&ep->conf_frame_Q)) {
110 			size = cq_howmany(&ep->conf_frame_Q);
111 			for (; size; size--) {
112 				struct packet *pkt = cq_get(&ep->conf_frame_Q);
113 
114 				kfree(pkt);
115 			}
116 			cq_delete(&ep->conf_frame_Q);
117 		}
118 
119 		if (kfifo_initialized(&ep->empty_frame_Q)) {
120 			size = cq_howmany(&ep->empty_frame_Q);
121 			for (; size; size--) {
122 				struct packet *pkt = cq_get(&ep->empty_frame_Q);
123 
124 				kfree(pkt);
125 			}
126 			cq_delete(&ep->empty_frame_Q);
127 		}
128 
129 		if (kfifo_initialized(&ep->dummy_packets_Q)) {
130 			size = cq_howmany(&ep->dummy_packets_Q);
131 			for (; size; size--) {
132 				u8 *buff = cq_get(&ep->dummy_packets_Q);
133 
134 				kfree(buff);
135 			}
136 			cq_delete(&ep->dummy_packets_Q);
137 		}
138 
139 		kfree(ep);
140 		usb->ep0 = NULL;
141 	}
142 }
143 
144 /*
145  * create the endpoint structure
146  *
147  * arguments:
148  * usb		A pointer to the data structure of the USB
149  * data_mem	The data memory partition(BUS)
150  * ring_len	TD ring length
151  */
152 u32 fhci_create_ep(struct fhci_usb *usb, enum fhci_mem_alloc data_mem,
153 			   u32 ring_len)
154 {
155 	struct endpoint *ep;
156 	struct usb_td __iomem *td;
157 	unsigned long ep_offset;
158 	char *err_for = "endpoint PRAM";
159 	int ep_mem_size;
160 	u32 i;
161 
162 	/* we need at least 3 TDs in the ring */
163 	if (!(ring_len > 2)) {
164 		fhci_err(usb->fhci, "illegal TD ring length parameters\n");
165 		return -EINVAL;
166 	}
167 
168 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
169 	if (!ep)
170 		return -ENOMEM;
171 
172 	ep_mem_size = ring_len * sizeof(*td) + sizeof(struct fhci_ep_pram);
173 	ep_offset = cpm_muram_alloc(ep_mem_size, 32);
174 	if (IS_ERR_VALUE(ep_offset))
175 		goto err;
176 	ep->td_base = cpm_muram_addr(ep_offset);
177 
178 	/* zero all queue pointers */
179 	if (cq_new(&ep->conf_frame_Q, ring_len + 2) ||
180 	    cq_new(&ep->empty_frame_Q, ring_len + 2) ||
181 	    cq_new(&ep->dummy_packets_Q, ring_len + 2)) {
182 		err_for = "frame_queues";
183 		goto err;
184 	}
185 
186 	for (i = 0; i < (ring_len + 1); i++) {
187 		struct packet *pkt;
188 		u8 *buff;
189 
190 		pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
191 		if (!pkt) {
192 			err_for = "frame";
193 			goto err;
194 		}
195 
196 		buff = kmalloc(1028 * sizeof(*buff), GFP_KERNEL);
197 		if (!buff) {
198 			kfree(pkt);
199 			err_for = "buffer";
200 			goto err;
201 		}
202 		cq_put(&ep->empty_frame_Q, pkt);
203 		cq_put(&ep->dummy_packets_Q, buff);
204 	}
205 
206 	/* we put the endpoint parameter RAM right behind the TD ring */
207 	ep->ep_pram_ptr = (void __iomem *)ep->td_base + sizeof(*td) * ring_len;
208 
209 	ep->conf_td = ep->td_base;
210 	ep->empty_td = ep->td_base;
211 
212 	ep->already_pushed_dummy_bd = false;
213 
214 	/* initialize tds */
215 	td = ep->td_base;
216 	for (i = 0; i < ring_len; i++) {
217 		out_be32(&td->buf_ptr, 0);
218 		out_be16(&td->status, 0);
219 		out_be16(&td->length, 0);
220 		out_be16(&td->extra, 0);
221 		td++;
222 	}
223 	td--;
224 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
225 	out_be16(&td->length, 0);
226 
227 	/* endpoint structure has been created */
228 	usb->ep0 = ep;
229 
230 	return 0;
231 err:
232 	fhci_ep0_free(usb);
233 	kfree(ep);
234 	fhci_err(usb->fhci, "no memory for the %s\n", err_for);
235 	return -ENOMEM;
236 }
237 
238 /*
239  * initialize the endpoint register according to the given parameters
240  *
241  * artuments:
242  * usb		A pointer to the data strucutre of the USB
243  * ep		A pointer to the endpoint structre
244  * data_mem	The data memory partition(BUS)
245  */
246 void fhci_init_ep_registers(struct fhci_usb *usb, struct endpoint *ep,
247 			    enum fhci_mem_alloc data_mem)
248 {
249 	u8 rt;
250 
251 	/* set the endpoint registers according to the endpoint */
252 	out_be16(&usb->fhci->regs->usb_ep[0],
253 		 USB_TRANS_CTR | USB_EP_MF | USB_EP_RTE);
254 	out_be16(&usb->fhci->pram->ep_ptr[0],
255 		 cpm_muram_offset(ep->ep_pram_ptr));
256 
257 	rt = (BUS_MODE_BO_BE | BUS_MODE_GBL);
258 #ifdef MULTI_DATA_BUS
259 	if (data_mem == MEM_SECONDARY)
260 		rt |= BUS_MODE_DTB;
261 #endif
262 	out_8(&ep->ep_pram_ptr->rx_func_code, rt);
263 	out_8(&ep->ep_pram_ptr->tx_func_code, rt);
264 	out_be16(&ep->ep_pram_ptr->rx_buff_len, 1028);
265 	out_be16(&ep->ep_pram_ptr->rx_base, 0);
266 	out_be16(&ep->ep_pram_ptr->tx_base, cpm_muram_offset(ep->td_base));
267 	out_be16(&ep->ep_pram_ptr->rx_bd_ptr, 0);
268 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr, cpm_muram_offset(ep->td_base));
269 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
270 }
271 
272 /*
273  * Collect the submitted frames and inform the application about them
274  * It is also preparing the TDs for new frames. If the Tx interrupts
275  * are disabled, the application should call that routine to get
276  * confirmation about the submitted frames. Otherwise, the routine is
277  * called from the interrupt service routine during the Tx interrupt.
278  * In that case the application is informed by calling the application
279  * specific 'fhci_transaction_confirm' routine
280  */
281 static void fhci_td_transaction_confirm(struct fhci_usb *usb)
282 {
283 	struct endpoint *ep = usb->ep0;
284 	struct packet *pkt;
285 	struct usb_td __iomem *td;
286 	u16 extra_data;
287 	u16 td_status;
288 	u16 td_length;
289 	u32 buf;
290 
291 	/*
292 	 * collect transmitted BDs from the chip. The routine clears all BDs
293 	 * with R bit = 0 and the pointer to data buffer is not NULL, that is
294 	 * BDs which point to the transmitted data buffer
295 	 */
296 	while (1) {
297 		td = ep->conf_td;
298 		td_status = in_be16(&td->status);
299 		td_length = in_be16(&td->length);
300 		buf = in_be32(&td->buf_ptr);
301 		extra_data = in_be16(&td->extra);
302 
303 		/* check if the TD is empty */
304 		if (!(!(td_status & TD_R) && ((td_status & ~TD_W) || buf)))
305 			break;
306 		/* check if it is a dummy buffer */
307 		else if ((buf == DUMMY_BD_BUFFER) && !(td_status & ~TD_W))
308 			break;
309 
310 		/* mark TD as empty */
311 		clrbits16(&td->status, ~TD_W);
312 		out_be16(&td->length, 0);
313 		out_be32(&td->buf_ptr, 0);
314 		out_be16(&td->extra, 0);
315 		/* advance the TD pointer */
316 		ep->conf_td = next_bd(ep->td_base, ep->conf_td, td_status);
317 
318 		/* check if it is a dummy buffer(type2) */
319 		if ((buf == DUMMY2_BD_BUFFER) && !(td_status & ~TD_W))
320 			continue;
321 
322 		pkt = cq_get(&ep->conf_frame_Q);
323 		if (!pkt)
324 			fhci_err(usb->fhci, "no frame to confirm\n");
325 
326 		if (td_status & TD_ERRORS) {
327 			if (td_status & TD_RXER) {
328 				if (td_status & TD_CR)
329 					pkt->status = USB_TD_RX_ER_CRC;
330 				else if (td_status & TD_AB)
331 					pkt->status = USB_TD_RX_ER_BITSTUFF;
332 				else if (td_status & TD_OV)
333 					pkt->status = USB_TD_RX_ER_OVERUN;
334 				else if (td_status & TD_BOV)
335 					pkt->status = USB_TD_RX_DATA_OVERUN;
336 				else if (td_status & TD_NO)
337 					pkt->status = USB_TD_RX_ER_NONOCT;
338 				else
339 					fhci_err(usb->fhci, "illegal error "
340 						 "occurred\n");
341 			} else if (td_status & TD_NAK)
342 				pkt->status = USB_TD_TX_ER_NAK;
343 			else if (td_status & TD_TO)
344 				pkt->status = USB_TD_TX_ER_TIMEOUT;
345 			else if (td_status & TD_UN)
346 				pkt->status = USB_TD_TX_ER_UNDERUN;
347 			else if (td_status & TD_STAL)
348 				pkt->status = USB_TD_TX_ER_STALL;
349 			else
350 				fhci_err(usb->fhci, "illegal error occurred\n");
351 		} else if ((extra_data & TD_TOK_IN) &&
352 				pkt->len > td_length - CRC_SIZE) {
353 			pkt->status = USB_TD_RX_DATA_UNDERUN;
354 		}
355 
356 		if (extra_data & TD_TOK_IN)
357 			pkt->len = td_length - CRC_SIZE;
358 		else if (pkt->info & PKT_ZLP)
359 			pkt->len = 0;
360 		else
361 			pkt->len = td_length;
362 
363 		fhci_transaction_confirm(usb, pkt);
364 	}
365 }
366 
367 /*
368  * Submitting a data frame to a specified endpoint of a USB device
369  * The frame is put in the driver's transmit queue for this endpoint
370  *
371  * Arguments:
372  * usb          A pointer to the USB structure
373  * pkt          A pointer to the user frame structure
374  * trans_type   Transaction tyep - IN,OUT or SETUP
375  * dest_addr    Device address - 0~127
376  * dest_ep      Endpoint number of the device - 0~16
377  * trans_mode   Pipe type - ISO,Interrupt,bulk or control
378  * dest_speed   USB speed - Low speed or FULL speed
379  * data_toggle  Data sequence toggle - 0 or 1
380  */
381 u32 fhci_host_transaction(struct fhci_usb *usb,
382 			  struct packet *pkt,
383 			  enum fhci_ta_type trans_type,
384 			  u8 dest_addr,
385 			  u8 dest_ep,
386 			  enum fhci_tf_mode trans_mode,
387 			  enum fhci_speed dest_speed, u8 data_toggle)
388 {
389 	struct endpoint *ep = usb->ep0;
390 	struct usb_td __iomem *td;
391 	u16 extra_data;
392 	u16 td_status;
393 
394 	fhci_usb_disable_interrupt(usb);
395 	/* start from the next BD that should be filled */
396 	td = ep->empty_td;
397 	td_status = in_be16(&td->status);
398 
399 	if (td_status & TD_R && in_be16(&td->length)) {
400 		/* if the TD is not free */
401 		fhci_usb_enable_interrupt(usb);
402 		return -1;
403 	}
404 
405 	/* get the next TD in the ring */
406 	ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
407 	fhci_usb_enable_interrupt(usb);
408 	pkt->priv_data = td;
409 	out_be32(&td->buf_ptr, virt_to_phys(pkt->data));
410 	/* sets up transaction parameters - addr,endp,dir,and type */
411 	extra_data = (dest_ep << TD_ENDP_SHIFT) | dest_addr;
412 	switch (trans_type) {
413 	case FHCI_TA_IN:
414 		extra_data |= TD_TOK_IN;
415 		break;
416 	case FHCI_TA_OUT:
417 		extra_data |= TD_TOK_OUT;
418 		break;
419 	case FHCI_TA_SETUP:
420 		extra_data |= TD_TOK_SETUP;
421 		break;
422 	}
423 	if (trans_mode == FHCI_TF_ISO)
424 		extra_data |= TD_ISO;
425 	out_be16(&td->extra, extra_data);
426 
427 	/* sets up the buffer descriptor */
428 	td_status = ((td_status & TD_W) | TD_R | TD_L | TD_I | TD_CNF);
429 	if (!(pkt->info & PKT_NO_CRC))
430 		td_status |= TD_TC;
431 
432 	switch (trans_type) {
433 	case FHCI_TA_IN:
434 		if (data_toggle)
435 			pkt->info |= PKT_PID_DATA1;
436 		else
437 			pkt->info |= PKT_PID_DATA0;
438 		break;
439 	default:
440 		if (data_toggle) {
441 			td_status |= TD_PID_DATA1;
442 			pkt->info |= PKT_PID_DATA1;
443 		} else {
444 			td_status |= TD_PID_DATA0;
445 			pkt->info |= PKT_PID_DATA0;
446 		}
447 		break;
448 	}
449 
450 	if ((dest_speed == FHCI_LOW_SPEED) &&
451 	    (usb->port_status == FHCI_PORT_FULL))
452 		td_status |= TD_LSP;
453 
454 	out_be16(&td->status, td_status);
455 
456 	/* set up buffer length */
457 	if (trans_type == FHCI_TA_IN)
458 		out_be16(&td->length, pkt->len + CRC_SIZE);
459 	else
460 		out_be16(&td->length, pkt->len);
461 
462 	/* put the frame to the confirmation queue */
463 	cq_put(&ep->conf_frame_Q, pkt);
464 
465 	if (cq_howmany(&ep->conf_frame_Q) == 1)
466 		out_8(&usb->fhci->regs->usb_comm, USB_CMD_STR_FIFO);
467 
468 	return 0;
469 }
470 
471 /* Reset the Tx BD ring */
472 void fhci_flush_bds(struct fhci_usb *usb)
473 {
474 	u16 extra_data;
475 	u16 td_status;
476 	u32 buf;
477 	struct usb_td __iomem *td;
478 	struct endpoint *ep = usb->ep0;
479 
480 	td = ep->td_base;
481 	while (1) {
482 		td_status = in_be16(&td->status);
483 		buf = in_be32(&td->buf_ptr);
484 		extra_data = in_be16(&td->extra);
485 
486 		/* if the TD is not empty - we'll confirm it as Timeout */
487 		if (td_status & TD_R)
488 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
489 		/* if this TD is dummy - let's skip this TD */
490 		else if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER)
491 			out_be32(&td->buf_ptr, DUMMY2_BD_BUFFER);
492 		/* if this is the last TD - break */
493 		if (td_status & TD_W)
494 			break;
495 
496 		td++;
497 	}
498 
499 	fhci_td_transaction_confirm(usb);
500 
501 	td = ep->td_base;
502 	do {
503 		out_be16(&td->status, 0);
504 		out_be16(&td->length, 0);
505 		out_be32(&td->buf_ptr, 0);
506 		out_be16(&td->extra, 0);
507 		td++;
508 	} while (!(in_be16(&td->status) & TD_W));
509 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
510 	out_be16(&td->length, 0);
511 	out_be32(&td->buf_ptr, 0);
512 	out_be16(&td->extra, 0);
513 
514 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
515 		 in_be16(&ep->ep_pram_ptr->tx_base));
516 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
517 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
518 	ep->empty_td = ep->td_base;
519 	ep->conf_td = ep->td_base;
520 }
521 
522 /*
523  * Flush all transmitted packets from TDs in the actual frame.
524  * This routine is called when something wrong with the controller and
525  * we want to get rid of the actual frame and start again next frame
526  */
527 void fhci_flush_actual_frame(struct fhci_usb *usb)
528 {
529 	u8 mode;
530 	u16 tb_ptr;
531 	u16 extra_data;
532 	u16 td_status;
533 	u32 buf_ptr;
534 	struct usb_td __iomem *td;
535 	struct endpoint *ep = usb->ep0;
536 
537 	/* disable the USB controller */
538 	mode = in_8(&usb->fhci->regs->usb_mod);
539 	out_8(&usb->fhci->regs->usb_mod, mode & ~USB_MODE_EN);
540 
541 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
542 	td = cpm_muram_addr(tb_ptr);
543 	td_status = in_be16(&td->status);
544 	buf_ptr = in_be32(&td->buf_ptr);
545 	extra_data = in_be16(&td->extra);
546 	do {
547 		if (td_status & TD_R) {
548 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
549 		} else {
550 			out_be32(&td->buf_ptr, 0);
551 			ep->already_pushed_dummy_bd = false;
552 			break;
553 		}
554 
555 		/* advance the TD pointer */
556 		td = next_bd(ep->td_base, td, td_status);
557 		td_status = in_be16(&td->status);
558 		buf_ptr = in_be32(&td->buf_ptr);
559 		extra_data = in_be16(&td->extra);
560 	} while ((td_status & TD_R) || buf_ptr);
561 
562 	fhci_td_transaction_confirm(usb);
563 
564 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
565 		 in_be16(&ep->ep_pram_ptr->tx_base));
566 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
567 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
568 	ep->empty_td = ep->td_base;
569 	ep->conf_td = ep->td_base;
570 
571 	usb->actual_frame->frame_status = FRAME_TIMER_END_TRANSMISSION;
572 
573 	/* reset the event register */
574 	out_be16(&usb->fhci->regs->usb_event, 0xffff);
575 	/* enable the USB controller */
576 	out_8(&usb->fhci->regs->usb_mod, mode | USB_MODE_EN);
577 }
578 
579 /* handles Tx confirm and Tx error interrupt */
580 void fhci_tx_conf_interrupt(struct fhci_usb *usb)
581 {
582 	fhci_td_transaction_confirm(usb);
583 
584 	/*
585 	 * Schedule another transaction to this frame only if we have
586 	 * already confirmed all transaction in the frame.
587 	 */
588 	if (((fhci_get_sof_timer_count(usb) < usb->max_frame_usage) ||
589 	     (usb->actual_frame->frame_status & FRAME_END_TRANSMISSION)) &&
590 	    (list_empty(&usb->actual_frame->tds_list)))
591 		fhci_schedule_transactions(usb);
592 }
593 
594 void fhci_host_transmit_actual_frame(struct fhci_usb *usb)
595 {
596 	u16 tb_ptr;
597 	u16 td_status;
598 	struct usb_td __iomem *td;
599 	struct endpoint *ep = usb->ep0;
600 
601 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
602 	td = cpm_muram_addr(tb_ptr);
603 
604 	if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER) {
605 		struct usb_td __iomem *old_td = td;
606 
607 		ep->already_pushed_dummy_bd = false;
608 		td_status = in_be16(&td->status);
609 		/* gets the next TD in the ring */
610 		td = next_bd(ep->td_base, td, td_status);
611 		tb_ptr = cpm_muram_offset(td);
612 		out_be16(&ep->ep_pram_ptr->tx_bd_ptr, tb_ptr);
613 
614 		/* start transmit only if we have something in the TDs */
615 		if (in_be16(&td->status) & TD_R)
616 			out_8(&usb->fhci->regs->usb_comm, USB_CMD_STR_FIFO);
617 
618 		if (in_be32(&ep->conf_td->buf_ptr) == DUMMY_BD_BUFFER) {
619 			out_be32(&old_td->buf_ptr, 0);
620 			ep->conf_td = next_bd(ep->td_base, ep->conf_td,
621 					      td_status);
622 		} else {
623 			out_be32(&old_td->buf_ptr, DUMMY2_BD_BUFFER);
624 		}
625 	}
626 }
627