xref: /openbmc/linux/drivers/usb/host/fhci-tds.c (revision 6c33a6f4)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Freescale QUICC Engine USB Host Controller Driver
4  *
5  * Copyright (c) Freescale Semicondutor, Inc. 2006.
6  *               Shlomi Gridish <gridish@freescale.com>
7  *               Jerry Huang <Chang-Ming.Huang@freescale.com>
8  * Copyright (c) Logic Product Development, Inc. 2007
9  *               Peter Barada <peterb@logicpd.com>
10  * Copyright (c) MontaVista Software, Inc. 2008.
11  *               Anton Vorontsov <avorontsov@ru.mvista.com>
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16 #include <linux/errno.h>
17 #include <linux/slab.h>
18 #include <linux/list.h>
19 #include <linux/io.h>
20 #include <linux/usb.h>
21 #include <linux/usb/hcd.h>
22 #include "fhci.h"
23 
24 #define DUMMY_BD_BUFFER  0xdeadbeef
25 #define DUMMY2_BD_BUFFER 0xbaadf00d
26 
27 /* Transaction Descriptors bits */
28 #define TD_R		0x8000 /* ready bit */
29 #define TD_W		0x2000 /* wrap bit */
30 #define TD_I		0x1000 /* interrupt on completion */
31 #define TD_L		0x0800 /* last */
32 #define TD_TC		0x0400 /* transmit CRC */
33 #define TD_CNF		0x0200 /* CNF - Must be always 1 */
34 #define TD_LSP		0x0100 /* Low-speed transaction */
35 #define TD_PID		0x00c0 /* packet id */
36 #define TD_RXER		0x0020 /* Rx error or not */
37 
38 #define TD_NAK		0x0010 /* No ack. */
39 #define TD_STAL		0x0008 /* Stall received */
40 #define TD_TO		0x0004 /* time out */
41 #define TD_UN		0x0002 /* underrun */
42 #define TD_NO		0x0010 /* Rx Non Octet Aligned Packet */
43 #define TD_AB		0x0008 /* Frame Aborted */
44 #define TD_CR		0x0004 /* CRC Error */
45 #define TD_OV		0x0002 /* Overrun */
46 #define TD_BOV		0x0001 /* Buffer Overrun */
47 
48 #define TD_ERRORS	(TD_NAK | TD_STAL | TD_TO | TD_UN | \
49 			 TD_NO | TD_AB | TD_CR | TD_OV | TD_BOV)
50 
51 #define TD_PID_DATA0	0x0080 /* Data 0 toggle */
52 #define TD_PID_DATA1	0x00c0 /* Data 1 toggle */
53 #define TD_PID_TOGGLE	0x00c0 /* Data 0/1 toggle mask */
54 
55 #define TD_TOK_SETUP	0x0000
56 #define TD_TOK_OUT	0x4000
57 #define TD_TOK_IN	0x8000
58 #define TD_ISO		0x1000
59 #define TD_ENDP		0x0780
60 #define TD_ADDR		0x007f
61 
62 #define TD_ENDP_SHIFT 7
63 
64 struct usb_td {
65 	__be16 status;
66 	__be16 length;
67 	__be32 buf_ptr;
68 	__be16 extra;
69 	__be16 reserved;
70 };
71 
72 static struct usb_td __iomem *next_bd(struct usb_td __iomem *base,
73 				      struct usb_td __iomem *td,
74 				      u16 status)
75 {
76 	if (status & TD_W)
77 		return base;
78 	else
79 		return ++td;
80 }
81 
82 void fhci_push_dummy_bd(struct endpoint *ep)
83 {
84 	if (!ep->already_pushed_dummy_bd) {
85 		u16 td_status = in_be16(&ep->empty_td->status);
86 
87 		out_be32(&ep->empty_td->buf_ptr, DUMMY_BD_BUFFER);
88 		/* get the next TD in the ring */
89 		ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
90 		ep->already_pushed_dummy_bd = true;
91 	}
92 }
93 
94 /* destroy an USB endpoint */
95 void fhci_ep0_free(struct fhci_usb *usb)
96 {
97 	struct endpoint *ep;
98 	int size;
99 
100 	ep = usb->ep0;
101 	if (ep) {
102 		if (ep->td_base)
103 			cpm_muram_free(cpm_muram_offset(ep->td_base));
104 
105 		if (kfifo_initialized(&ep->conf_frame_Q)) {
106 			size = cq_howmany(&ep->conf_frame_Q);
107 			for (; size; size--) {
108 				struct packet *pkt = cq_get(&ep->conf_frame_Q);
109 
110 				kfree(pkt);
111 			}
112 			cq_delete(&ep->conf_frame_Q);
113 		}
114 
115 		if (kfifo_initialized(&ep->empty_frame_Q)) {
116 			size = cq_howmany(&ep->empty_frame_Q);
117 			for (; size; size--) {
118 				struct packet *pkt = cq_get(&ep->empty_frame_Q);
119 
120 				kfree(pkt);
121 			}
122 			cq_delete(&ep->empty_frame_Q);
123 		}
124 
125 		if (kfifo_initialized(&ep->dummy_packets_Q)) {
126 			size = cq_howmany(&ep->dummy_packets_Q);
127 			for (; size; size--) {
128 				u8 *buff = cq_get(&ep->dummy_packets_Q);
129 
130 				kfree(buff);
131 			}
132 			cq_delete(&ep->dummy_packets_Q);
133 		}
134 
135 		kfree(ep);
136 		usb->ep0 = NULL;
137 	}
138 }
139 
140 /*
141  * create the endpoint structure
142  *
143  * arguments:
144  * usb		A pointer to the data structure of the USB
145  * data_mem	The data memory partition(BUS)
146  * ring_len	TD ring length
147  */
148 u32 fhci_create_ep(struct fhci_usb *usb, enum fhci_mem_alloc data_mem,
149 			   u32 ring_len)
150 {
151 	struct endpoint *ep;
152 	struct usb_td __iomem *td;
153 	unsigned long ep_offset;
154 	char *err_for = "endpoint PRAM";
155 	int ep_mem_size;
156 	u32 i;
157 
158 	/* we need at least 3 TDs in the ring */
159 	if (!(ring_len > 2)) {
160 		fhci_err(usb->fhci, "illegal TD ring length parameters\n");
161 		return -EINVAL;
162 	}
163 
164 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
165 	if (!ep)
166 		return -ENOMEM;
167 
168 	ep_mem_size = ring_len * sizeof(*td) + sizeof(struct fhci_ep_pram);
169 	ep_offset = cpm_muram_alloc(ep_mem_size, 32);
170 	if (IS_ERR_VALUE(ep_offset))
171 		goto err;
172 	ep->td_base = cpm_muram_addr(ep_offset);
173 
174 	/* zero all queue pointers */
175 	if (cq_new(&ep->conf_frame_Q, ring_len + 2) ||
176 	    cq_new(&ep->empty_frame_Q, ring_len + 2) ||
177 	    cq_new(&ep->dummy_packets_Q, ring_len + 2)) {
178 		err_for = "frame_queues";
179 		goto err;
180 	}
181 
182 	for (i = 0; i < (ring_len + 1); i++) {
183 		struct packet *pkt;
184 		u8 *buff;
185 
186 		pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
187 		if (!pkt) {
188 			err_for = "frame";
189 			goto err;
190 		}
191 
192 		buff = kmalloc_array(1028, sizeof(*buff), GFP_KERNEL);
193 		if (!buff) {
194 			kfree(pkt);
195 			err_for = "buffer";
196 			goto err;
197 		}
198 		cq_put(&ep->empty_frame_Q, pkt);
199 		cq_put(&ep->dummy_packets_Q, buff);
200 	}
201 
202 	/* we put the endpoint parameter RAM right behind the TD ring */
203 	ep->ep_pram_ptr = (void __iomem *)ep->td_base + sizeof(*td) * ring_len;
204 
205 	ep->conf_td = ep->td_base;
206 	ep->empty_td = ep->td_base;
207 
208 	ep->already_pushed_dummy_bd = false;
209 
210 	/* initialize tds */
211 	td = ep->td_base;
212 	for (i = 0; i < ring_len; i++) {
213 		out_be32(&td->buf_ptr, 0);
214 		out_be16(&td->status, 0);
215 		out_be16(&td->length, 0);
216 		out_be16(&td->extra, 0);
217 		td++;
218 	}
219 	td--;
220 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
221 	out_be16(&td->length, 0);
222 
223 	/* endpoint structure has been created */
224 	usb->ep0 = ep;
225 
226 	return 0;
227 err:
228 	fhci_ep0_free(usb);
229 	kfree(ep);
230 	fhci_err(usb->fhci, "no memory for the %s\n", err_for);
231 	return -ENOMEM;
232 }
233 
234 /*
235  * initialize the endpoint register according to the given parameters
236  *
237  * artuments:
238  * usb		A pointer to the data strucutre of the USB
239  * ep		A pointer to the endpoint structre
240  * data_mem	The data memory partition(BUS)
241  */
242 void fhci_init_ep_registers(struct fhci_usb *usb, struct endpoint *ep,
243 			    enum fhci_mem_alloc data_mem)
244 {
245 	u8 rt;
246 
247 	/* set the endpoint registers according to the endpoint */
248 	out_be16(&usb->fhci->regs->usb_usep[0],
249 		 USB_TRANS_CTR | USB_EP_MF | USB_EP_RTE);
250 	out_be16(&usb->fhci->pram->ep_ptr[0],
251 		 cpm_muram_offset(ep->ep_pram_ptr));
252 
253 	rt = (BUS_MODE_BO_BE | BUS_MODE_GBL);
254 #ifdef MULTI_DATA_BUS
255 	if (data_mem == MEM_SECONDARY)
256 		rt |= BUS_MODE_DTB;
257 #endif
258 	out_8(&ep->ep_pram_ptr->rx_func_code, rt);
259 	out_8(&ep->ep_pram_ptr->tx_func_code, rt);
260 	out_be16(&ep->ep_pram_ptr->rx_buff_len, 1028);
261 	out_be16(&ep->ep_pram_ptr->rx_base, 0);
262 	out_be16(&ep->ep_pram_ptr->tx_base, cpm_muram_offset(ep->td_base));
263 	out_be16(&ep->ep_pram_ptr->rx_bd_ptr, 0);
264 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr, cpm_muram_offset(ep->td_base));
265 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
266 }
267 
268 /*
269  * Collect the submitted frames and inform the application about them
270  * It is also preparing the TDs for new frames. If the Tx interrupts
271  * are disabled, the application should call that routine to get
272  * confirmation about the submitted frames. Otherwise, the routine is
273  * called from the interrupt service routine during the Tx interrupt.
274  * In that case the application is informed by calling the application
275  * specific 'fhci_transaction_confirm' routine
276  */
277 static void fhci_td_transaction_confirm(struct fhci_usb *usb)
278 {
279 	struct endpoint *ep = usb->ep0;
280 	struct packet *pkt;
281 	struct usb_td __iomem *td;
282 	u16 extra_data;
283 	u16 td_status;
284 	u16 td_length;
285 	u32 buf;
286 
287 	/*
288 	 * collect transmitted BDs from the chip. The routine clears all BDs
289 	 * with R bit = 0 and the pointer to data buffer is not NULL, that is
290 	 * BDs which point to the transmitted data buffer
291 	 */
292 	while (1) {
293 		td = ep->conf_td;
294 		td_status = in_be16(&td->status);
295 		td_length = in_be16(&td->length);
296 		buf = in_be32(&td->buf_ptr);
297 		extra_data = in_be16(&td->extra);
298 
299 		/* check if the TD is empty */
300 		if (!(!(td_status & TD_R) && ((td_status & ~TD_W) || buf)))
301 			break;
302 		/* check if it is a dummy buffer */
303 		else if ((buf == DUMMY_BD_BUFFER) && !(td_status & ~TD_W))
304 			break;
305 
306 		/* mark TD as empty */
307 		clrbits16(&td->status, ~TD_W);
308 		out_be16(&td->length, 0);
309 		out_be32(&td->buf_ptr, 0);
310 		out_be16(&td->extra, 0);
311 		/* advance the TD pointer */
312 		ep->conf_td = next_bd(ep->td_base, ep->conf_td, td_status);
313 
314 		/* check if it is a dummy buffer(type2) */
315 		if ((buf == DUMMY2_BD_BUFFER) && !(td_status & ~TD_W))
316 			continue;
317 
318 		pkt = cq_get(&ep->conf_frame_Q);
319 		if (!pkt)
320 			fhci_err(usb->fhci, "no frame to confirm\n");
321 
322 		if (td_status & TD_ERRORS) {
323 			if (td_status & TD_RXER) {
324 				if (td_status & TD_CR)
325 					pkt->status = USB_TD_RX_ER_CRC;
326 				else if (td_status & TD_AB)
327 					pkt->status = USB_TD_RX_ER_BITSTUFF;
328 				else if (td_status & TD_OV)
329 					pkt->status = USB_TD_RX_ER_OVERUN;
330 				else if (td_status & TD_BOV)
331 					pkt->status = USB_TD_RX_DATA_OVERUN;
332 				else if (td_status & TD_NO)
333 					pkt->status = USB_TD_RX_ER_NONOCT;
334 				else
335 					fhci_err(usb->fhci, "illegal error "
336 						 "occurred\n");
337 			} else if (td_status & TD_NAK)
338 				pkt->status = USB_TD_TX_ER_NAK;
339 			else if (td_status & TD_TO)
340 				pkt->status = USB_TD_TX_ER_TIMEOUT;
341 			else if (td_status & TD_UN)
342 				pkt->status = USB_TD_TX_ER_UNDERUN;
343 			else if (td_status & TD_STAL)
344 				pkt->status = USB_TD_TX_ER_STALL;
345 			else
346 				fhci_err(usb->fhci, "illegal error occurred\n");
347 		} else if ((extra_data & TD_TOK_IN) &&
348 				pkt->len > td_length - CRC_SIZE) {
349 			pkt->status = USB_TD_RX_DATA_UNDERUN;
350 		}
351 
352 		if (extra_data & TD_TOK_IN)
353 			pkt->len = td_length - CRC_SIZE;
354 		else if (pkt->info & PKT_ZLP)
355 			pkt->len = 0;
356 		else
357 			pkt->len = td_length;
358 
359 		fhci_transaction_confirm(usb, pkt);
360 	}
361 }
362 
363 /*
364  * Submitting a data frame to a specified endpoint of a USB device
365  * The frame is put in the driver's transmit queue for this endpoint
366  *
367  * Arguments:
368  * usb          A pointer to the USB structure
369  * pkt          A pointer to the user frame structure
370  * trans_type   Transaction tyep - IN,OUT or SETUP
371  * dest_addr    Device address - 0~127
372  * dest_ep      Endpoint number of the device - 0~16
373  * trans_mode   Pipe type - ISO,Interrupt,bulk or control
374  * dest_speed   USB speed - Low speed or FULL speed
375  * data_toggle  Data sequence toggle - 0 or 1
376  */
377 u32 fhci_host_transaction(struct fhci_usb *usb,
378 			  struct packet *pkt,
379 			  enum fhci_ta_type trans_type,
380 			  u8 dest_addr,
381 			  u8 dest_ep,
382 			  enum fhci_tf_mode trans_mode,
383 			  enum fhci_speed dest_speed, u8 data_toggle)
384 {
385 	struct endpoint *ep = usb->ep0;
386 	struct usb_td __iomem *td;
387 	u16 extra_data;
388 	u16 td_status;
389 
390 	fhci_usb_disable_interrupt(usb);
391 	/* start from the next BD that should be filled */
392 	td = ep->empty_td;
393 	td_status = in_be16(&td->status);
394 
395 	if (td_status & TD_R && in_be16(&td->length)) {
396 		/* if the TD is not free */
397 		fhci_usb_enable_interrupt(usb);
398 		return -1;
399 	}
400 
401 	/* get the next TD in the ring */
402 	ep->empty_td = next_bd(ep->td_base, ep->empty_td, td_status);
403 	fhci_usb_enable_interrupt(usb);
404 	pkt->priv_data = td;
405 	out_be32(&td->buf_ptr, virt_to_phys(pkt->data));
406 	/* sets up transaction parameters - addr,endp,dir,and type */
407 	extra_data = (dest_ep << TD_ENDP_SHIFT) | dest_addr;
408 	switch (trans_type) {
409 	case FHCI_TA_IN:
410 		extra_data |= TD_TOK_IN;
411 		break;
412 	case FHCI_TA_OUT:
413 		extra_data |= TD_TOK_OUT;
414 		break;
415 	case FHCI_TA_SETUP:
416 		extra_data |= TD_TOK_SETUP;
417 		break;
418 	}
419 	if (trans_mode == FHCI_TF_ISO)
420 		extra_data |= TD_ISO;
421 	out_be16(&td->extra, extra_data);
422 
423 	/* sets up the buffer descriptor */
424 	td_status = ((td_status & TD_W) | TD_R | TD_L | TD_I | TD_CNF);
425 	if (!(pkt->info & PKT_NO_CRC))
426 		td_status |= TD_TC;
427 
428 	switch (trans_type) {
429 	case FHCI_TA_IN:
430 		if (data_toggle)
431 			pkt->info |= PKT_PID_DATA1;
432 		else
433 			pkt->info |= PKT_PID_DATA0;
434 		break;
435 	default:
436 		if (data_toggle) {
437 			td_status |= TD_PID_DATA1;
438 			pkt->info |= PKT_PID_DATA1;
439 		} else {
440 			td_status |= TD_PID_DATA0;
441 			pkt->info |= PKT_PID_DATA0;
442 		}
443 		break;
444 	}
445 
446 	if ((dest_speed == FHCI_LOW_SPEED) &&
447 	    (usb->port_status == FHCI_PORT_FULL))
448 		td_status |= TD_LSP;
449 
450 	out_be16(&td->status, td_status);
451 
452 	/* set up buffer length */
453 	if (trans_type == FHCI_TA_IN)
454 		out_be16(&td->length, pkt->len + CRC_SIZE);
455 	else
456 		out_be16(&td->length, pkt->len);
457 
458 	/* put the frame to the confirmation queue */
459 	cq_put(&ep->conf_frame_Q, pkt);
460 
461 	if (cq_howmany(&ep->conf_frame_Q) == 1)
462 		out_8(&usb->fhci->regs->usb_uscom, USB_CMD_STR_FIFO);
463 
464 	return 0;
465 }
466 
467 /* Reset the Tx BD ring */
468 void fhci_flush_bds(struct fhci_usb *usb)
469 {
470 	u16 extra_data;
471 	u16 td_status;
472 	u32 buf;
473 	struct usb_td __iomem *td;
474 	struct endpoint *ep = usb->ep0;
475 
476 	td = ep->td_base;
477 	while (1) {
478 		td_status = in_be16(&td->status);
479 		buf = in_be32(&td->buf_ptr);
480 		extra_data = in_be16(&td->extra);
481 
482 		/* if the TD is not empty - we'll confirm it as Timeout */
483 		if (td_status & TD_R)
484 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
485 		/* if this TD is dummy - let's skip this TD */
486 		else if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER)
487 			out_be32(&td->buf_ptr, DUMMY2_BD_BUFFER);
488 		/* if this is the last TD - break */
489 		if (td_status & TD_W)
490 			break;
491 
492 		td++;
493 	}
494 
495 	fhci_td_transaction_confirm(usb);
496 
497 	td = ep->td_base;
498 	do {
499 		out_be16(&td->status, 0);
500 		out_be16(&td->length, 0);
501 		out_be32(&td->buf_ptr, 0);
502 		out_be16(&td->extra, 0);
503 		td++;
504 	} while (!(in_be16(&td->status) & TD_W));
505 	out_be16(&td->status, TD_W); /* for last TD set Wrap bit */
506 	out_be16(&td->length, 0);
507 	out_be32(&td->buf_ptr, 0);
508 	out_be16(&td->extra, 0);
509 
510 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
511 		 in_be16(&ep->ep_pram_ptr->tx_base));
512 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
513 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
514 	ep->empty_td = ep->td_base;
515 	ep->conf_td = ep->td_base;
516 }
517 
518 /*
519  * Flush all transmitted packets from TDs in the actual frame.
520  * This routine is called when something wrong with the controller and
521  * we want to get rid of the actual frame and start again next frame
522  */
523 void fhci_flush_actual_frame(struct fhci_usb *usb)
524 {
525 	u8 mode;
526 	u16 tb_ptr;
527 	u16 extra_data;
528 	u16 td_status;
529 	u32 buf_ptr;
530 	struct usb_td __iomem *td;
531 	struct endpoint *ep = usb->ep0;
532 
533 	/* disable the USB controller */
534 	mode = in_8(&usb->fhci->regs->usb_usmod);
535 	out_8(&usb->fhci->regs->usb_usmod, mode & ~USB_MODE_EN);
536 
537 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
538 	td = cpm_muram_addr(tb_ptr);
539 	td_status = in_be16(&td->status);
540 	buf_ptr = in_be32(&td->buf_ptr);
541 	extra_data = in_be16(&td->extra);
542 	do {
543 		if (td_status & TD_R) {
544 			out_be16(&td->status, (td_status & ~TD_R) | TD_TO);
545 		} else {
546 			out_be32(&td->buf_ptr, 0);
547 			ep->already_pushed_dummy_bd = false;
548 			break;
549 		}
550 
551 		/* advance the TD pointer */
552 		td = next_bd(ep->td_base, td, td_status);
553 		td_status = in_be16(&td->status);
554 		buf_ptr = in_be32(&td->buf_ptr);
555 		extra_data = in_be16(&td->extra);
556 	} while ((td_status & TD_R) || buf_ptr);
557 
558 	fhci_td_transaction_confirm(usb);
559 
560 	out_be16(&ep->ep_pram_ptr->tx_bd_ptr,
561 		 in_be16(&ep->ep_pram_ptr->tx_base));
562 	out_be32(&ep->ep_pram_ptr->tx_state, 0);
563 	out_be16(&ep->ep_pram_ptr->tx_cnt, 0);
564 	ep->empty_td = ep->td_base;
565 	ep->conf_td = ep->td_base;
566 
567 	usb->actual_frame->frame_status = FRAME_TIMER_END_TRANSMISSION;
568 
569 	/* reset the event register */
570 	out_be16(&usb->fhci->regs->usb_usber, 0xffff);
571 	/* enable the USB controller */
572 	out_8(&usb->fhci->regs->usb_usmod, mode | USB_MODE_EN);
573 }
574 
575 /* handles Tx confirm and Tx error interrupt */
576 void fhci_tx_conf_interrupt(struct fhci_usb *usb)
577 {
578 	fhci_td_transaction_confirm(usb);
579 
580 	/*
581 	 * Schedule another transaction to this frame only if we have
582 	 * already confirmed all transaction in the frame.
583 	 */
584 	if (((fhci_get_sof_timer_count(usb) < usb->max_frame_usage) ||
585 	     (usb->actual_frame->frame_status & FRAME_END_TRANSMISSION)) &&
586 	    (list_empty(&usb->actual_frame->tds_list)))
587 		fhci_schedule_transactions(usb);
588 }
589 
590 void fhci_host_transmit_actual_frame(struct fhci_usb *usb)
591 {
592 	u16 tb_ptr;
593 	u16 td_status;
594 	struct usb_td __iomem *td;
595 	struct endpoint *ep = usb->ep0;
596 
597 	tb_ptr = in_be16(&ep->ep_pram_ptr->tx_bd_ptr);
598 	td = cpm_muram_addr(tb_ptr);
599 
600 	if (in_be32(&td->buf_ptr) == DUMMY_BD_BUFFER) {
601 		struct usb_td __iomem *old_td = td;
602 
603 		ep->already_pushed_dummy_bd = false;
604 		td_status = in_be16(&td->status);
605 		/* gets the next TD in the ring */
606 		td = next_bd(ep->td_base, td, td_status);
607 		tb_ptr = cpm_muram_offset(td);
608 		out_be16(&ep->ep_pram_ptr->tx_bd_ptr, tb_ptr);
609 
610 		/* start transmit only if we have something in the TDs */
611 		if (in_be16(&td->status) & TD_R)
612 			out_8(&usb->fhci->regs->usb_uscom, USB_CMD_STR_FIFO);
613 
614 		if (in_be32(&ep->conf_td->buf_ptr) == DUMMY_BD_BUFFER) {
615 			out_be32(&old_td->buf_ptr, 0);
616 			ep->conf_td = next_bd(ep->td_base, ep->conf_td,
617 					      td_status);
618 		} else {
619 			out_be32(&old_td->buf_ptr, DUMMY2_BD_BUFFER);
620 		}
621 	}
622 }
623