xref: /openbmc/linux/drivers/usb/host/fhci-tds.c (revision a09d2831)
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/list.h>
22 #include <linux/io.h>
23 #include <linux/usb.h>
24 #include "../core/hcd.h"
25 #include "fhci.h"
26 
27 #define DUMMY_BD_BUFFER  0xdeadbeef
28 #define DUMMY2_BD_BUFFER 0xbaadf00d
29 
30 /* Transaction Descriptors bits */
31 #define TD_R		0x8000 /* ready bit */
32 #define TD_W		0x2000 /* wrap bit */
33 #define TD_I		0x1000 /* interrupt on completion */
34 #define TD_L		0x0800 /* last */
35 #define TD_TC		0x0400 /* transmit CRC */
36 #define TD_CNF		0x0200 /* CNF - Must be always 1 */
37 #define TD_LSP		0x0100 /* Low-speed transaction */
38 #define TD_PID		0x00c0 /* packet id */
39 #define TD_RXER		0x0020 /* Rx error or not */
40 
41 #define TD_NAK		0x0010 /* No ack. */
42 #define TD_STAL		0x0008 /* Stall recieved */
43 #define TD_TO		0x0004 /* time out */
44 #define TD_UN		0x0002 /* underrun */
45 #define TD_NO		0x0010 /* Rx Non Octet Aligned Packet */
46 #define TD_AB		0x0008 /* Frame Aborted */
47 #define TD_CR		0x0004 /* CRC Error */
48 #define TD_OV		0x0002 /* Overrun */
49 #define TD_BOV		0x0001 /* Buffer Overrun */
50 
51 #define TD_ERRORS	(TD_NAK | TD_STAL | TD_TO | TD_UN | \
52 			 TD_NO | TD_AB | TD_CR | TD_OV | TD_BOV)
53 
54 #define TD_PID_DATA0	0x0080 /* Data 0 toggle */
55 #define TD_PID_DATA1	0x00c0 /* Data 1 toggle */
56 #define TD_PID_TOGGLE	0x00c0 /* Data 0/1 toggle mask */
57 
58 #define TD_TOK_SETUP	0x0000
59 #define TD_TOK_OUT	0x4000
60 #define TD_TOK_IN	0x8000
61 #define TD_ISO		0x1000
62 #define TD_ENDP		0x0780
63 #define TD_ADDR		0x007f
64 
65 #define TD_ENDP_SHIFT 7
66 
67 struct usb_td {
68 	__be16 status;
69 	__be16 length;
70 	__be32 buf_ptr;
71 	__be16 extra;
72 	__be16 reserved;
73 };
74 
75 static struct usb_td __iomem *next_bd(struct usb_td __iomem *base,
76 				      struct usb_td __iomem *td,
77 				      u16 status)
78 {
79 	if (status & TD_W)
80 		return base;
81 	else
82 		return ++td;
83 }
84 
85 void fhci_push_dummy_bd(struct endpoint *ep)
86 {
87 	if (ep->already_pushed_dummy_bd == false) {
88 		u16 td_status = in_be16(&ep->empty_td->status);
89 
90 		out_be32(&ep->empty_td->buf_ptr, DUMMY_BD_BUFFER);
91 		/* get the next TD in the ring */
92 		ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
93 		ep->already_pushed_dummy_bd = true;
94 	}
95 }
96 
97 /* destroy an USB endpoint */
98 void fhci_ep0_free(struct fhci_usb *usb)
99 {
100 	struct endpoint *ep;
101 	int size;
102 
103 	ep = usb->ep0;
104 	if (ep) {
105 		if (ep->td_base)
106 			cpm_muram_free(cpm_muram_offset(ep->td_base));
107 
108 		if (ep->conf_frame_Q) {
109 			size = cq_howmany(&ep->conf_frame_Q);
110 			for (; size; size--) {
111 				struct packet *pkt = cq_get(&ep->conf_frame_Q);
112 
113 				kfree(pkt);
114 			}
115 			cq_delete(&ep->conf_frame_Q);
116 		}
117 
118 		if (ep->empty_frame_Q) {
119 			size = cq_howmany(&ep->empty_frame_Q);
120 			for (; size; size--) {
121 				struct packet *pkt = cq_get(&ep->empty_frame_Q);
122 
123 				kfree(pkt);
124 			}
125 			cq_delete(&ep->empty_frame_Q);
126 		}
127 
128 		if (ep->dummy_packets_Q) {
129 			size = cq_howmany(&ep->dummy_packets_Q);
130 			for (; size; size--) {
131 				u8 *buff = cq_get(&ep->dummy_packets_Q);
132 
133 				kfree(buff);
134 			}
135 			cq_delete(&ep->dummy_packets_Q);
136 		}
137 
138 		kfree(ep);
139 		usb->ep0 = NULL;
140 	}
141 }
142 
143 /*
144  * create the endpoint structure
145  *
146  * arguments:
147  * usb		A pointer to the data structure of the USB
148  * data_mem	The data memory partition(BUS)
149  * ring_len	TD ring length
150  */
151 u32 fhci_create_ep(struct fhci_usb *usb, enum fhci_mem_alloc data_mem,
152 			   u32 ring_len)
153 {
154 	struct endpoint *ep;
155 	struct usb_td __iomem *td;
156 	unsigned long ep_offset;
157 	char *err_for = "enpoint PRAM";
158 	int ep_mem_size;
159 	u32 i;
160 
161 	/* we need at least 3 TDs in the ring */
162 	if (!(ring_len > 2)) {
163 		fhci_err(usb->fhci, "illegal TD ring length parameters\n");
164 		return -EINVAL;
165 	}
166 
167 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
168 	if (!ep)
169 		return -ENOMEM;
170 
171 	ep_mem_size = ring_len * sizeof(*td) + sizeof(struct fhci_ep_pram);
172 	ep_offset = cpm_muram_alloc(ep_mem_size, 32);
173 	if (IS_ERR_VALUE(ep_offset))
174 		goto err;
175 	ep->td_base = cpm_muram_addr(ep_offset);
176 
177 	/* zero all queue pointers */
178 	if (cq_new(&ep->conf_frame_Q, ring_len + 2) ||
179 	    cq_new(&ep->empty_frame_Q, ring_len + 2) ||
180 	    cq_new(&ep->dummy_packets_Q, ring_len + 2)) {
181 		err_for = "frame_queues";
182 		goto err;
183 	}
184 
185 	for (i = 0; i < (ring_len + 1); i++) {
186 		struct packet *pkt;
187 		u8 *buff;
188 
189 		pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
190 		if (!pkt) {
191 			err_for = "frame";
192 			goto err;
193 		}
194 
195 		buff = kmalloc(1028 * sizeof(*buff), GFP_KERNEL);
196 		if (!buff) {
197 			kfree(pkt);
198 			err_for = "buffer";
199 			goto err;
200 		}
201 		cq_put(&ep->empty_frame_Q, pkt);
202 		cq_put(&ep->dummy_packets_Q, buff);
203 	}
204 
205 	/* we put the endpoint parameter RAM right behind the TD ring */
206 	ep->ep_pram_ptr = (void __iomem *)ep->td_base + sizeof(*td) * ring_len;
207 
208 	ep->conf_td = ep->td_base;
209 	ep->empty_td = ep->td_base;
210 
211 	ep->already_pushed_dummy_bd = false;
212 
213 	/* initialize tds */
214 	td = ep->td_base;
215 	for (i = 0; i < ring_len; i++) {
216 		out_be32(&td->buf_ptr, 0);
217 		out_be16(&td->status, 0);
218 		out_be16(&td->length, 0);
219 		out_be16(&td->extra, 0);
220 		td++;
221 	}
222 	td--;
223 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
224 	out_be16(&td->length, 0);
225 
226 	/* endpoint structure has been created */
227 	usb->ep0 = ep;
228 
229 	return 0;
230 err:
231 	fhci_ep0_free(usb);
232 	kfree(ep);
233 	fhci_err(usb->fhci, "no memory for the %s\n", err_for);
234 	return -ENOMEM;
235 }
236 
237 /*
238  * initialize the endpoint register according to the given parameters
239  *
240  * artuments:
241  * usb		A pointer to the data strucutre of the USB
242  * ep		A pointer to the endpoint structre
243  * data_mem	The data memory partition(BUS)
244  */
245 void fhci_init_ep_registers(struct fhci_usb *usb, struct endpoint *ep,
246 			    enum fhci_mem_alloc data_mem)
247 {
248 	u8 rt;
249 
250 	/* set the endpoint registers according to the endpoint */
251 	out_be16(&usb->fhci->regs->usb_ep[0],
252 		 USB_TRANS_CTR | USB_EP_MF | USB_EP_RTE);
253 	out_be16(&usb->fhci->pram->ep_ptr[0],
254 		 cpm_muram_offset(ep->ep_pram_ptr));
255 
256 	rt = (BUS_MODE_BO_BE | BUS_MODE_GBL);
257 #ifdef MULTI_DATA_BUS
258 	if (data_mem == MEM_SECONDARY)
259 		rt |= BUS_MODE_DTB;
260 #endif
261 	out_8(&ep->ep_pram_ptr->rx_func_code, rt);
262 	out_8(&ep->ep_pram_ptr->tx_func_code, rt);
263 	out_be16(&ep->ep_pram_ptr->rx_buff_len, 1028);
264 	out_be16(&ep->ep_pram_ptr->rx_base, 0);
265 	out_be16(&ep->ep_pram_ptr->tx_base, cpm_muram_offset(ep->td_base));
266 	out_be16(&ep->ep_pram_ptr->rx_bd_ptr, 0);
267 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr, cpm_muram_offset(ep->td_base));
268 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
269 }
270 
271 /*
272  * Collect the submitted frames and inform the application about them
273  * It is also prepearing the TDs for new frames. If the Tx interrupts
274  * are diabled, the application should call that routine to get
275  * confirmation about the submitted frames. Otherwise, the routine is
276  * called frome the interrupt service routine during the Tx interrupt.
277  * In that case the application is informed by calling the application
278  * specific 'fhci_transaction_confirm' routine
279  */
280 static void fhci_td_transaction_confirm(struct fhci_usb *usb)
281 {
282 	struct endpoint *ep = usb->ep0;
283 	struct packet *pkt;
284 	struct usb_td __iomem *td;
285 	u16 extra_data;
286 	u16 td_status;
287 	u16 td_length;
288 	u32 buf;
289 
290 	/*
291 	 * collect transmitted BDs from the chip. The routine clears all BDs
292 	 * with R bit = 0 and the pointer to data buffer is not NULL, that is
293 	 * BDs which point to the transmitted data buffer
294 	 */
295 	while (1) {
296 		td = ep->conf_td;
297 		td_status = in_be16(&td->status);
298 		td_length = in_be16(&td->length);
299 		buf = in_be32(&td->buf_ptr);
300 		extra_data = in_be16(&td->extra);
301 
302 		/* check if the TD is empty */
303 		if (!(!(td_status & TD_R) && ((td_status & ~TD_W) || buf)))
304 			break;
305 		/* check if it is a dummy buffer */
306 		else if ((buf == DUMMY_BD_BUFFER) && !(td_status & ~TD_W))
307 			break;
308 
309 		/* mark TD as empty */
310 		clrbits16(&td->status, ~TD_W);
311 		out_be16(&td->length, 0);
312 		out_be32(&td->buf_ptr, 0);
313 		out_be16(&td->extra, 0);
314 		/* advance the TD pointer */
315 		ep->conf_td = next_bd(ep->td_base, ep->conf_td, td_status);
316 
317 		/* check if it is a dummy buffer(type2) */
318 		if ((buf == DUMMY2_BD_BUFFER) && !(td_status & ~TD_W))
319 			continue;
320 
321 		pkt = cq_get(&ep->conf_frame_Q);
322 		if (!pkt)
323 			fhci_err(usb->fhci, "no frame to confirm\n");
324 
325 		if (td_status & TD_ERRORS) {
326 			if (td_status & TD_RXER) {
327 				if (td_status & TD_CR)
328 					pkt->status = USB_TD_RX_ER_CRC;
329 				else if (td_status & TD_AB)
330 					pkt->status = USB_TD_RX_ER_BITSTUFF;
331 				else if (td_status & TD_OV)
332 					pkt->status = USB_TD_RX_ER_OVERUN;
333 				else if (td_status & TD_BOV)
334 					pkt->status = USB_TD_RX_DATA_OVERUN;
335 				else if (td_status & TD_NO)
336 					pkt->status = USB_TD_RX_ER_NONOCT;
337 				else
338 					fhci_err(usb->fhci, "illegal error "
339 						 "occured\n");
340 			} else if (td_status & TD_NAK)
341 				pkt->status = USB_TD_TX_ER_NAK;
342 			else if (td_status & TD_TO)
343 				pkt->status = USB_TD_TX_ER_TIMEOUT;
344 			else if (td_status & TD_UN)
345 				pkt->status = USB_TD_TX_ER_UNDERUN;
346 			else if (td_status & TD_STAL)
347 				pkt->status = USB_TD_TX_ER_STALL;
348 			else
349 				fhci_err(usb->fhci, "illegal error occured\n");
350 		} else if ((extra_data & TD_TOK_IN) &&
351 				pkt->len > td_length - CRC_SIZE) {
352 			pkt->status = USB_TD_RX_DATA_UNDERUN;
353 		}
354 
355 		if (extra_data & TD_TOK_IN)
356 			pkt->len = td_length - CRC_SIZE;
357 		else if (pkt->info & PKT_ZLP)
358 			pkt->len = 0;
359 		else
360 			pkt->len = td_length;
361 
362 		fhci_transaction_confirm(usb, pkt);
363 	}
364 }
365 
366 /*
367  * Submitting a data frame to a specified endpoint of a USB device
368  * The frame is put in the driver's transmit queue for this endpoint
369  *
370  * Arguments:
371  * usb          A pointer to the USB structure
372  * pkt          A pointer to the user frame structure
373  * trans_type   Transaction tyep - IN,OUT or SETUP
374  * dest_addr    Device address - 0~127
375  * dest_ep      Endpoint number of the device - 0~16
376  * trans_mode   Pipe type - ISO,Interrupt,bulk or control
377  * dest_speed   USB speed - Low speed or FULL speed
378  * data_toggle  Data sequence toggle - 0 or 1
379  */
380 u32 fhci_host_transaction(struct fhci_usb *usb,
381 			  struct packet *pkt,
382 			  enum fhci_ta_type trans_type,
383 			  u8 dest_addr,
384 			  u8 dest_ep,
385 			  enum fhci_tf_mode trans_mode,
386 			  enum fhci_speed dest_speed, u8 data_toggle)
387 {
388 	struct endpoint *ep = usb->ep0;
389 	struct usb_td __iomem *td;
390 	u16 extra_data;
391 	u16 td_status;
392 
393 	fhci_usb_disable_interrupt(usb);
394 	/* start from the next BD that should be filled */
395 	td = ep->empty_td;
396 	td_status = in_be16(&td->status);
397 
398 	if (td_status & TD_R && in_be16(&td->length)) {
399 		/* if the TD is not free */
400 		fhci_usb_enable_interrupt(usb);
401 		return -1;
402 	}
403 
404 	/* get the next TD in the ring */
405 	ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
406 	fhci_usb_enable_interrupt(usb);
407 	pkt->priv_data = td;
408 	out_be32(&td->buf_ptr, virt_to_phys(pkt->data));
409 	/* sets up transaction parameters - addr,endp,dir,and type */
410 	extra_data = (dest_ep << TD_ENDP_SHIFT) | dest_addr;
411 	switch (trans_type) {
412 	case FHCI_TA_IN:
413 		extra_data |= TD_TOK_IN;
414 		break;
415 	case FHCI_TA_OUT:
416 		extra_data |= TD_TOK_OUT;
417 		break;
418 	case FHCI_TA_SETUP:
419 		extra_data |= TD_TOK_SETUP;
420 		break;
421 	}
422 	if (trans_mode == FHCI_TF_ISO)
423 		extra_data |= TD_ISO;
424 	out_be16(&td->extra, extra_data);
425 
426 	/* sets up the buffer descriptor */
427 	td_status = ((td_status & TD_W) | TD_R | TD_L | TD_I | TD_CNF);
428 	if (!(pkt->info & PKT_NO_CRC))
429 		td_status |= TD_TC;
430 
431 	switch (trans_type) {
432 	case FHCI_TA_IN:
433 		if (data_toggle)
434 			pkt->info |= PKT_PID_DATA1;
435 		else
436 			pkt->info |= PKT_PID_DATA0;
437 		break;
438 	default:
439 		if (data_toggle) {
440 			td_status |= TD_PID_DATA1;
441 			pkt->info |= PKT_PID_DATA1;
442 		} else {
443 			td_status |= TD_PID_DATA0;
444 			pkt->info |= PKT_PID_DATA0;
445 		}
446 		break;
447 	}
448 
449 	if ((dest_speed == FHCI_LOW_SPEED) &&
450 	    (usb->port_status == FHCI_PORT_FULL))
451 		td_status |= TD_LSP;
452 
453 	out_be16(&td->status, td_status);
454 
455 	/* set up buffer length */
456 	if (trans_type == FHCI_TA_IN)
457 		out_be16(&td->length, pkt->len + CRC_SIZE);
458 	else
459 		out_be16(&td->length, pkt->len);
460 
461 	/* put the frame to the confirmation queue */
462 	cq_put(&ep->conf_frame_Q, pkt);
463 
464 	if (cq_howmany(&ep->conf_frame_Q) == 1)
465 		out_8(&usb->fhci->regs->usb_comm, USB_CMD_STR_FIFO);
466 
467 	return 0;
468 }
469 
470 /* Reset the Tx BD ring */
471 void fhci_flush_bds(struct fhci_usb *usb)
472 {
473 	u16 extra_data;
474 	u16 td_status;
475 	u32 buf;
476 	struct usb_td __iomem *td;
477 	struct endpoint *ep = usb->ep0;
478 
479 	td = ep->td_base;
480 	while (1) {
481 		td_status = in_be16(&td->status);
482 		buf = in_be32(&td->buf_ptr);
483 		extra_data = in_be16(&td->extra);
484 
485 		/* if the TD is not empty - we'll confirm it as Timeout */
486 		if (td_status & TD_R)
487 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
488 		/* if this TD is dummy - let's skip this TD */
489 		else if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER)
490 			out_be32(&td->buf_ptr, DUMMY2_BD_BUFFER);
491 		/* if this is the last TD - break */
492 		if (td_status & TD_W)
493 			break;
494 
495 		td++;
496 	}
497 
498 	fhci_td_transaction_confirm(usb);
499 
500 	td = ep->td_base;
501 	do {
502 		out_be16(&td->status, 0);
503 		out_be16(&td->length, 0);
504 		out_be32(&td->buf_ptr, 0);
505 		out_be16(&td->extra, 0);
506 		td++;
507 	} while (!(in_be16(&td->status) & TD_W));
508 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
509 	out_be16(&td->length, 0);
510 	out_be32(&td->buf_ptr, 0);
511 	out_be16(&td->extra, 0);
512 
513 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
514 		 in_be16(&ep->ep_pram_ptr->tx_base));
515 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
516 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
517 	ep->empty_td = ep->td_base;
518 	ep->conf_td = ep->td_base;
519 }
520 
521 /*
522  * Flush all transmitted packets from TDs in the actual frame.
523  * This routine is called when something wrong with the controller and
524  * we want to get rid of the actual frame and start again next frame
525  */
526 void fhci_flush_actual_frame(struct fhci_usb *usb)
527 {
528 	u8 mode;
529 	u16 tb_ptr;
530 	u16 extra_data;
531 	u16 td_status;
532 	u32 buf_ptr;
533 	struct usb_td __iomem *td;
534 	struct endpoint *ep = usb->ep0;
535 
536 	/* disable the USB controller */
537 	mode = in_8(&usb->fhci->regs->usb_mod);
538 	out_8(&usb->fhci->regs->usb_mod, mode & ~USB_MODE_EN);
539 
540 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
541 	td = cpm_muram_addr(tb_ptr);
542 	td_status = in_be16(&td->status);
543 	buf_ptr = in_be32(&td->buf_ptr);
544 	extra_data = in_be16(&td->extra);
545 	do {
546 		if (td_status & TD_R) {
547 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
548 		} else {
549 			out_be32(&td->buf_ptr, 0);
550 			ep->already_pushed_dummy_bd = false;
551 			break;
552 		}
553 
554 		/* advance the TD pointer */
555 		td = next_bd(ep->td_base, td, td_status);
556 		td_status = in_be16(&td->status);
557 		buf_ptr = in_be32(&td->buf_ptr);
558 		extra_data = in_be16(&td->extra);
559 	} while ((td_status & TD_R) || buf_ptr);
560 
561 	fhci_td_transaction_confirm(usb);
562 
563 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
564 		 in_be16(&ep->ep_pram_ptr->tx_base));
565 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
566 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
567 	ep->empty_td = ep->td_base;
568 	ep->conf_td = ep->td_base;
569 
570 	usb->actual_frame->frame_status = FRAME_TIMER_END_TRANSMISSION;
571 
572 	/* reset the event register */
573 	out_be16(&usb->fhci->regs->usb_event, 0xffff);
574 	/* enable the USB controller */
575 	out_8(&usb->fhci->regs->usb_mod, mode | USB_MODE_EN);
576 }
577 
578 /* handles Tx confirm and Tx error interrupt */
579 void fhci_tx_conf_interrupt(struct fhci_usb *usb)
580 {
581 	fhci_td_transaction_confirm(usb);
582 
583 	/*
584 	 * Schedule another transaction to this frame only if we have
585 	 * already confirmed all transaction in the frame.
586 	 */
587 	if (((fhci_get_sof_timer_count(usb) < usb->max_frame_usage) ||
588 	     (usb->actual_frame->frame_status & FRAME_END_TRANSMISSION)) &&
589 	    (list_empty(&usb->actual_frame->tds_list)))
590 		fhci_schedule_transactions(usb);
591 }
592 
593 void fhci_host_transmit_actual_frame(struct fhci_usb *usb)
594 {
595 	u16 tb_ptr;
596 	u16 td_status;
597 	struct usb_td __iomem *td;
598 	struct endpoint *ep = usb->ep0;
599 
600 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
601 	td = cpm_muram_addr(tb_ptr);
602 
603 	if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER) {
604 		struct usb_td __iomem *old_td = td;
605 
606 		ep->already_pushed_dummy_bd = false;
607 		td_status = in_be16(&td->status);
608 		/* gets the next TD in the ring */
609 		td = next_bd(ep->td_base, td, td_status);
610 		tb_ptr = cpm_muram_offset(td);
611 		out_be16(&ep->ep_pram_ptr->tx_bd_ptr, tb_ptr);
612 
613 		/* start transmit only if we have something in the TDs */
614 		if (in_be16(&td->status) & TD_R)
615 			out_8(&usb->fhci->regs->usb_comm, USB_CMD_STR_FIFO);
616 
617 		if (in_be32(&ep->conf_td->buf_ptr) == DUMMY_BD_BUFFER) {
618 			out_be32(&old_td->buf_ptr, 0);
619 			ep->conf_td = next_bd(ep->td_base, ep->conf_td,
620 					      td_status);
621 		} else {
622 			out_be32(&old_td->buf_ptr, DUMMY2_BD_BUFFER);
623 		}
624 	}
625 }
626