xref: /openbmc/linux/drivers/net/wireless/ath/ath5k/dma.c (revision 930beb5a)
1 /*
2  * Copyright (c) 2004-2008 Reyk Floeter <reyk@openbsd.org>
3  * Copyright (c) 2006-2008 Nick Kossifidis <mickflemm@gmail.com>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  *
17  */
18 
19 /*************************************\
20 * DMA and interrupt masking functions *
21 \*************************************/
22 
23 /**
24  * DOC: DMA and interrupt masking functions
25  *
26  * Here we setup descriptor pointers (rxdp/txdp) start/stop dma engine and
27  * handle queue setup for 5210 chipset (rest are handled on qcu.c).
28  * Also we setup interrupt mask register (IMR) and read the various interrupt
29  * status registers (ISR).
30  */
31 
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33 
34 #include "ath5k.h"
35 #include "reg.h"
36 #include "debug.h"
37 
38 
39 /*********\
40 * Receive *
41 \*********/
42 
43 /**
44  * ath5k_hw_start_rx_dma() - Start DMA receive
45  * @ah:	The &struct ath5k_hw
46  */
47 void
48 ath5k_hw_start_rx_dma(struct ath5k_hw *ah)
49 {
50 	ath5k_hw_reg_write(ah, AR5K_CR_RXE, AR5K_CR);
51 	ath5k_hw_reg_read(ah, AR5K_CR);
52 }
53 
54 /**
55  * ath5k_hw_stop_rx_dma() - Stop DMA receive
56  * @ah:	The &struct ath5k_hw
57  */
58 static int
59 ath5k_hw_stop_rx_dma(struct ath5k_hw *ah)
60 {
61 	unsigned int i;
62 
63 	ath5k_hw_reg_write(ah, AR5K_CR_RXD, AR5K_CR);
64 
65 	/*
66 	 * It may take some time to disable the DMA receive unit
67 	 */
68 	for (i = 1000; i > 0 &&
69 			(ath5k_hw_reg_read(ah, AR5K_CR) & AR5K_CR_RXE) != 0;
70 			i--)
71 		udelay(100);
72 
73 	if (!i)
74 		ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
75 				"failed to stop RX DMA !\n");
76 
77 	return i ? 0 : -EBUSY;
78 }
79 
80 /**
81  * ath5k_hw_get_rxdp() - Get RX Descriptor's address
82  * @ah: The &struct ath5k_hw
83  */
84 u32
85 ath5k_hw_get_rxdp(struct ath5k_hw *ah)
86 {
87 	return ath5k_hw_reg_read(ah, AR5K_RXDP);
88 }
89 
90 /**
91  * ath5k_hw_set_rxdp() - Set RX Descriptor's address
92  * @ah: The &struct ath5k_hw
93  * @phys_addr: RX descriptor address
94  *
95  * Returns -EIO if rx is active
96  */
97 int
98 ath5k_hw_set_rxdp(struct ath5k_hw *ah, u32 phys_addr)
99 {
100 	if (ath5k_hw_reg_read(ah, AR5K_CR) & AR5K_CR_RXE) {
101 		ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
102 				"tried to set RXDP while rx was active !\n");
103 		return -EIO;
104 	}
105 
106 	ath5k_hw_reg_write(ah, phys_addr, AR5K_RXDP);
107 	return 0;
108 }
109 
110 
111 /**********\
112 * Transmit *
113 \**********/
114 
115 /**
116  * ath5k_hw_start_tx_dma() - Start DMA transmit for a specific queue
117  * @ah: The &struct ath5k_hw
118  * @queue: The hw queue number
119  *
120  * Start DMA transmit for a specific queue and since 5210 doesn't have
121  * QCU/DCU, set up queue parameters for 5210 here based on queue type (one
122  * queue for normal data and one queue for beacons). For queue setup
123  * on newer chips check out qcu.c. Returns -EINVAL if queue number is out
124  * of range or if queue is already disabled.
125  *
126  * NOTE: Must be called after setting up tx control descriptor for that
127  * queue (see below).
128  */
129 int
130 ath5k_hw_start_tx_dma(struct ath5k_hw *ah, unsigned int queue)
131 {
132 	u32 tx_queue;
133 
134 	AR5K_ASSERT_ENTRY(queue, ah->ah_capabilities.cap_queues.q_tx_num);
135 
136 	/* Return if queue is declared inactive */
137 	if (ah->ah_txq[queue].tqi_type == AR5K_TX_QUEUE_INACTIVE)
138 		return -EINVAL;
139 
140 	if (ah->ah_version == AR5K_AR5210) {
141 		tx_queue = ath5k_hw_reg_read(ah, AR5K_CR);
142 
143 		/*
144 		 * Set the queue by type on 5210
145 		 */
146 		switch (ah->ah_txq[queue].tqi_type) {
147 		case AR5K_TX_QUEUE_DATA:
148 			tx_queue |= AR5K_CR_TXE0 & ~AR5K_CR_TXD0;
149 			break;
150 		case AR5K_TX_QUEUE_BEACON:
151 			tx_queue |= AR5K_CR_TXE1 & ~AR5K_CR_TXD1;
152 			ath5k_hw_reg_write(ah, AR5K_BCR_TQ1V | AR5K_BCR_BDMAE,
153 					AR5K_BSR);
154 			break;
155 		case AR5K_TX_QUEUE_CAB:
156 			tx_queue |= AR5K_CR_TXE1 & ~AR5K_CR_TXD1;
157 			ath5k_hw_reg_write(ah, AR5K_BCR_TQ1FV | AR5K_BCR_TQ1V |
158 				AR5K_BCR_BDMAE, AR5K_BSR);
159 			break;
160 		default:
161 			return -EINVAL;
162 		}
163 		/* Start queue */
164 		ath5k_hw_reg_write(ah, tx_queue, AR5K_CR);
165 		ath5k_hw_reg_read(ah, AR5K_CR);
166 	} else {
167 		/* Return if queue is disabled */
168 		if (AR5K_REG_READ_Q(ah, AR5K_QCU_TXD, queue))
169 			return -EIO;
170 
171 		/* Start queue */
172 		AR5K_REG_WRITE_Q(ah, AR5K_QCU_TXE, queue);
173 	}
174 
175 	return 0;
176 }
177 
178 /**
179  * ath5k_hw_stop_tx_dma() - Stop DMA transmit on a specific queue
180  * @ah: The &struct ath5k_hw
181  * @queue: The hw queue number
182  *
183  * Stop DMA transmit on a specific hw queue and drain queue so we don't
184  * have any pending frames. Returns -EBUSY if we still have pending frames,
185  * -EINVAL if queue number is out of range or inactive.
186  */
187 static int
188 ath5k_hw_stop_tx_dma(struct ath5k_hw *ah, unsigned int queue)
189 {
190 	unsigned int i = 40;
191 	u32 tx_queue, pending;
192 
193 	AR5K_ASSERT_ENTRY(queue, ah->ah_capabilities.cap_queues.q_tx_num);
194 
195 	/* Return if queue is declared inactive */
196 	if (ah->ah_txq[queue].tqi_type == AR5K_TX_QUEUE_INACTIVE)
197 		return -EINVAL;
198 
199 	if (ah->ah_version == AR5K_AR5210) {
200 		tx_queue = ath5k_hw_reg_read(ah, AR5K_CR);
201 
202 		/*
203 		 * Set by queue type
204 		 */
205 		switch (ah->ah_txq[queue].tqi_type) {
206 		case AR5K_TX_QUEUE_DATA:
207 			tx_queue |= AR5K_CR_TXD0 & ~AR5K_CR_TXE0;
208 			break;
209 		case AR5K_TX_QUEUE_BEACON:
210 		case AR5K_TX_QUEUE_CAB:
211 			/* XXX Fix me... */
212 			tx_queue |= AR5K_CR_TXD1 & ~AR5K_CR_TXD1;
213 			ath5k_hw_reg_write(ah, 0, AR5K_BSR);
214 			break;
215 		default:
216 			return -EINVAL;
217 		}
218 
219 		/* Stop queue */
220 		ath5k_hw_reg_write(ah, tx_queue, AR5K_CR);
221 		ath5k_hw_reg_read(ah, AR5K_CR);
222 	} else {
223 
224 		/*
225 		 * Enable DCU early termination to quickly
226 		 * flush any pending frames from QCU
227 		 */
228 		AR5K_REG_ENABLE_BITS(ah, AR5K_QUEUE_MISC(queue),
229 					AR5K_QCU_MISC_DCU_EARLY);
230 
231 		/*
232 		 * Schedule TX disable and wait until queue is empty
233 		 */
234 		AR5K_REG_WRITE_Q(ah, AR5K_QCU_TXD, queue);
235 
236 		/* Wait for queue to stop */
237 		for (i = 1000; i > 0 &&
238 		(AR5K_REG_READ_Q(ah, AR5K_QCU_TXE, queue) != 0);
239 		i--)
240 			udelay(100);
241 
242 		if (AR5K_REG_READ_Q(ah, AR5K_QCU_TXE, queue))
243 			ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
244 				"queue %i didn't stop !\n", queue);
245 
246 		/* Check for pending frames */
247 		i = 1000;
248 		do {
249 			pending = ath5k_hw_reg_read(ah,
250 				AR5K_QUEUE_STATUS(queue)) &
251 				AR5K_QCU_STS_FRMPENDCNT;
252 			udelay(100);
253 		} while (--i && pending);
254 
255 		/* For 2413+ order PCU to drop packets using
256 		 * QUIET mechanism */
257 		if (ah->ah_mac_version >= (AR5K_SREV_AR2414 >> 4) &&
258 		    pending) {
259 			/* Set periodicity and duration */
260 			ath5k_hw_reg_write(ah,
261 				AR5K_REG_SM(100, AR5K_QUIET_CTL2_QT_PER)|
262 				AR5K_REG_SM(10, AR5K_QUIET_CTL2_QT_DUR),
263 				AR5K_QUIET_CTL2);
264 
265 			/* Enable quiet period for current TSF */
266 			ath5k_hw_reg_write(ah,
267 				AR5K_QUIET_CTL1_QT_EN |
268 				AR5K_REG_SM(ath5k_hw_reg_read(ah,
269 						AR5K_TSF_L32_5211) >> 10,
270 						AR5K_QUIET_CTL1_NEXT_QT_TSF),
271 				AR5K_QUIET_CTL1);
272 
273 			/* Force channel idle high */
274 			AR5K_REG_ENABLE_BITS(ah, AR5K_DIAG_SW_5211,
275 					AR5K_DIAG_SW_CHANNEL_IDLE_HIGH);
276 
277 			/* Wait a while and disable mechanism */
278 			udelay(400);
279 			AR5K_REG_DISABLE_BITS(ah, AR5K_QUIET_CTL1,
280 						AR5K_QUIET_CTL1_QT_EN);
281 
282 			/* Re-check for pending frames */
283 			i = 100;
284 			do {
285 				pending = ath5k_hw_reg_read(ah,
286 					AR5K_QUEUE_STATUS(queue)) &
287 					AR5K_QCU_STS_FRMPENDCNT;
288 				udelay(100);
289 			} while (--i && pending);
290 
291 			AR5K_REG_DISABLE_BITS(ah, AR5K_DIAG_SW_5211,
292 					AR5K_DIAG_SW_CHANNEL_IDLE_HIGH);
293 
294 			if (pending)
295 				ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
296 					"quiet mechanism didn't work q:%i !\n",
297 					queue);
298 		}
299 
300 		/*
301 		 * Disable DCU early termination
302 		 */
303 		AR5K_REG_DISABLE_BITS(ah, AR5K_QUEUE_MISC(queue),
304 					AR5K_QCU_MISC_DCU_EARLY);
305 
306 		/* Clear register */
307 		ath5k_hw_reg_write(ah, 0, AR5K_QCU_TXD);
308 		if (pending) {
309 			ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
310 					"tx dma didn't stop (q:%i, frm:%i) !\n",
311 					queue, pending);
312 			return -EBUSY;
313 		}
314 	}
315 
316 	/* TODO: Check for success on 5210 else return error */
317 	return 0;
318 }
319 
320 /**
321  * ath5k_hw_stop_beacon_queue() - Stop beacon queue
322  * @ah: The &struct ath5k_hw
323  * @queue: The queue number
324  *
325  * Returns -EIO if queue didn't stop
326  */
327 int
328 ath5k_hw_stop_beacon_queue(struct ath5k_hw *ah, unsigned int queue)
329 {
330 	int ret;
331 	ret = ath5k_hw_stop_tx_dma(ah, queue);
332 	if (ret) {
333 		ATH5K_DBG(ah, ATH5K_DEBUG_DMA,
334 				"beacon queue didn't stop !\n");
335 		return -EIO;
336 	}
337 	return 0;
338 }
339 
340 /**
341  * ath5k_hw_get_txdp() - Get TX Descriptor's address for a specific queue
342  * @ah: The &struct ath5k_hw
343  * @queue: The hw queue number
344  *
345  * Get TX descriptor's address for a specific queue. For 5210 we ignore
346  * the queue number and use tx queue type since we only have 2 queues.
347  * We use TXDP0 for normal data queue and TXDP1 for beacon queue.
348  * For newer chips with QCU/DCU we just read the corresponding TXDP register.
349  *
350  * XXX: Is TXDP read and clear ?
351  */
352 u32
353 ath5k_hw_get_txdp(struct ath5k_hw *ah, unsigned int queue)
354 {
355 	u16 tx_reg;
356 
357 	AR5K_ASSERT_ENTRY(queue, ah->ah_capabilities.cap_queues.q_tx_num);
358 
359 	/*
360 	 * Get the transmit queue descriptor pointer from the selected queue
361 	 */
362 	/*5210 doesn't have QCU*/
363 	if (ah->ah_version == AR5K_AR5210) {
364 		switch (ah->ah_txq[queue].tqi_type) {
365 		case AR5K_TX_QUEUE_DATA:
366 			tx_reg = AR5K_NOQCU_TXDP0;
367 			break;
368 		case AR5K_TX_QUEUE_BEACON:
369 		case AR5K_TX_QUEUE_CAB:
370 			tx_reg = AR5K_NOQCU_TXDP1;
371 			break;
372 		default:
373 			return 0xffffffff;
374 		}
375 	} else {
376 		tx_reg = AR5K_QUEUE_TXDP(queue);
377 	}
378 
379 	return ath5k_hw_reg_read(ah, tx_reg);
380 }
381 
382 /**
383  * ath5k_hw_set_txdp() - Set TX Descriptor's address for a specific queue
384  * @ah: The &struct ath5k_hw
385  * @queue: The hw queue number
386  * @phys_addr: The physical address
387  *
388  * Set TX descriptor's address for a specific queue. For 5210 we ignore
389  * the queue number and we use tx queue type since we only have 2 queues
390  * so as above we use TXDP0 for normal data queue and TXDP1 for beacon queue.
391  * For newer chips with QCU/DCU we just set the corresponding TXDP register.
392  * Returns -EINVAL if queue type is invalid for 5210 and -EIO if queue is still
393  * active.
394  */
395 int
396 ath5k_hw_set_txdp(struct ath5k_hw *ah, unsigned int queue, u32 phys_addr)
397 {
398 	u16 tx_reg;
399 
400 	AR5K_ASSERT_ENTRY(queue, ah->ah_capabilities.cap_queues.q_tx_num);
401 
402 	/*
403 	 * Set the transmit queue descriptor pointer register by type
404 	 * on 5210
405 	 */
406 	if (ah->ah_version == AR5K_AR5210) {
407 		switch (ah->ah_txq[queue].tqi_type) {
408 		case AR5K_TX_QUEUE_DATA:
409 			tx_reg = AR5K_NOQCU_TXDP0;
410 			break;
411 		case AR5K_TX_QUEUE_BEACON:
412 		case AR5K_TX_QUEUE_CAB:
413 			tx_reg = AR5K_NOQCU_TXDP1;
414 			break;
415 		default:
416 			return -EINVAL;
417 		}
418 	} else {
419 		/*
420 		 * Set the transmit queue descriptor pointer for
421 		 * the selected queue on QCU for 5211+
422 		 * (this won't work if the queue is still active)
423 		 */
424 		if (AR5K_REG_READ_Q(ah, AR5K_QCU_TXE, queue))
425 			return -EIO;
426 
427 		tx_reg = AR5K_QUEUE_TXDP(queue);
428 	}
429 
430 	/* Set descriptor pointer */
431 	ath5k_hw_reg_write(ah, phys_addr, tx_reg);
432 
433 	return 0;
434 }
435 
436 /**
437  * ath5k_hw_update_tx_triglevel() - Update tx trigger level
438  * @ah: The &struct ath5k_hw
439  * @increase: Flag to force increase of trigger level
440  *
441  * This function increases/decreases the tx trigger level for the tx fifo
442  * buffer (aka FIFO threshold) that is used to indicate when PCU flushes
443  * the buffer and transmits its data. Lowering this results sending small
444  * frames more quickly but can lead to tx underruns, raising it a lot can
445  * result other problems. Right now we start with the lowest possible
446  * (64Bytes) and if we get tx underrun we increase it using the increase
447  * flag. Returns -EIO if we have reached maximum/minimum.
448  *
449  * XXX: Link this with tx DMA size ?
450  * XXX2: Use it to save interrupts ?
451  */
452 int
453 ath5k_hw_update_tx_triglevel(struct ath5k_hw *ah, bool increase)
454 {
455 	u32 trigger_level, imr;
456 	int ret = -EIO;
457 
458 	/*
459 	 * Disable interrupts by setting the mask
460 	 */
461 	imr = ath5k_hw_set_imr(ah, ah->ah_imr & ~AR5K_INT_GLOBAL);
462 
463 	trigger_level = AR5K_REG_MS(ath5k_hw_reg_read(ah, AR5K_TXCFG),
464 			AR5K_TXCFG_TXFULL);
465 
466 	if (!increase) {
467 		if (--trigger_level < AR5K_TUNE_MIN_TX_FIFO_THRES)
468 			goto done;
469 	} else
470 		trigger_level +=
471 			((AR5K_TUNE_MAX_TX_FIFO_THRES - trigger_level) / 2);
472 
473 	/*
474 	 * Update trigger level on success
475 	 */
476 	if (ah->ah_version == AR5K_AR5210)
477 		ath5k_hw_reg_write(ah, trigger_level, AR5K_TRIG_LVL);
478 	else
479 		AR5K_REG_WRITE_BITS(ah, AR5K_TXCFG,
480 				AR5K_TXCFG_TXFULL, trigger_level);
481 
482 	ret = 0;
483 
484 done:
485 	/*
486 	 * Restore interrupt mask
487 	 */
488 	ath5k_hw_set_imr(ah, imr);
489 
490 	return ret;
491 }
492 
493 
494 /*******************\
495 * Interrupt masking *
496 \*******************/
497 
498 /**
499  * ath5k_hw_is_intr_pending() - Check if we have pending interrupts
500  * @ah: The &struct ath5k_hw
501  *
502  * Check if we have pending interrupts to process. Returns 1 if we
503  * have pending interrupts and 0 if we haven't.
504  */
505 bool
506 ath5k_hw_is_intr_pending(struct ath5k_hw *ah)
507 {
508 	return ath5k_hw_reg_read(ah, AR5K_INTPEND) == 1 ? 1 : 0;
509 }
510 
511 /**
512  * ath5k_hw_get_isr() - Get interrupt status
513  * @ah: The @struct ath5k_hw
514  * @interrupt_mask: Driver's interrupt mask used to filter out
515  * interrupts in sw.
516  *
517  * This function is used inside our interrupt handler to determine the reason
518  * for the interrupt by reading Primary Interrupt Status Register. Returns an
519  * abstract interrupt status mask which is mostly ISR with some uncommon bits
520  * being mapped on some standard non hw-specific positions
521  * (check out &ath5k_int).
522  *
523  * NOTE: We do write-to-clear, so the active PISR/SISR bits at the time this
524  * function gets called are cleared on return.
525  */
526 int
527 ath5k_hw_get_isr(struct ath5k_hw *ah, enum ath5k_int *interrupt_mask)
528 {
529 	u32 data = 0;
530 
531 	/*
532 	 * Read interrupt status from Primary Interrupt
533 	 * Register.
534 	 *
535 	 * Note: PISR/SISR Not available on 5210
536 	 */
537 	if (ah->ah_version == AR5K_AR5210) {
538 		u32 isr = 0;
539 		isr = ath5k_hw_reg_read(ah, AR5K_ISR);
540 		if (unlikely(isr == AR5K_INT_NOCARD)) {
541 			*interrupt_mask = isr;
542 			return -ENODEV;
543 		}
544 
545 		/*
546 		 * Filter out the non-common bits from the interrupt
547 		 * status.
548 		 */
549 		*interrupt_mask = (isr & AR5K_INT_COMMON) & ah->ah_imr;
550 
551 		/* Hanlde INT_FATAL */
552 		if (unlikely(isr & (AR5K_ISR_SSERR | AR5K_ISR_MCABT
553 						| AR5K_ISR_DPERR)))
554 			*interrupt_mask |= AR5K_INT_FATAL;
555 
556 		/*
557 		 * XXX: BMISS interrupts may occur after association.
558 		 * I found this on 5210 code but it needs testing. If this is
559 		 * true we should disable them before assoc and re-enable them
560 		 * after a successful assoc + some jiffies.
561 			interrupt_mask &= ~AR5K_INT_BMISS;
562 		 */
563 
564 		data = isr;
565 	} else {
566 		u32 pisr = 0;
567 		u32 pisr_clear = 0;
568 		u32 sisr0 = 0;
569 		u32 sisr1 = 0;
570 		u32 sisr2 = 0;
571 		u32 sisr3 = 0;
572 		u32 sisr4 = 0;
573 
574 		/* Read PISR and SISRs... */
575 		pisr = ath5k_hw_reg_read(ah, AR5K_PISR);
576 		if (unlikely(pisr == AR5K_INT_NOCARD)) {
577 			*interrupt_mask = pisr;
578 			return -ENODEV;
579 		}
580 
581 		sisr0 = ath5k_hw_reg_read(ah, AR5K_SISR0);
582 		sisr1 = ath5k_hw_reg_read(ah, AR5K_SISR1);
583 		sisr2 = ath5k_hw_reg_read(ah, AR5K_SISR2);
584 		sisr3 = ath5k_hw_reg_read(ah, AR5K_SISR3);
585 		sisr4 = ath5k_hw_reg_read(ah, AR5K_SISR4);
586 
587 		/*
588 		 * PISR holds the logical OR of interrupt bits
589 		 * from SISR registers:
590 		 *
591 		 * TXOK and TXDESC  -> Logical OR of TXOK and TXDESC
592 		 *			per-queue bits on SISR0
593 		 *
594 		 * TXERR and TXEOL -> Logical OR of TXERR and TXEOL
595 		 *			per-queue bits on SISR1
596 		 *
597 		 * TXURN -> Logical OR of TXURN per-queue bits on SISR2
598 		 *
599 		 * HIUERR -> Logical OR of MCABT, SSERR and DPER bits on SISR2
600 		 *
601 		 * BCNMISC -> Logical OR of TIM, CAB_END, DTIM_SYNC
602 		 *		BCN_TIMEOUT, CAB_TIMEOUT and DTIM
603 		 *		(and TSFOOR ?) bits on SISR2
604 		 *
605 		 * QCBRORN and QCBRURN -> Logical OR of QCBRORN and
606 		 *			QCBRURN per-queue bits on SISR3
607 		 * QTRIG -> Logical OR of QTRIG per-queue bits on SISR4
608 		 *
609 		 * If we clean these bits on PISR we 'll also clear all
610 		 * related bits from SISRs, e.g. if we write the TXOK bit on
611 		 * PISR we 'll clean all TXOK bits from SISR0 so if a new TXOK
612 		 * interrupt got fired for another queue while we were reading
613 		 * the interrupt registers and we write back the TXOK bit on
614 		 * PISR we 'll lose it. So make sure that we don't write back
615 		 * on PISR any bits that come from SISRs. Clearing them from
616 		 * SISRs will also clear PISR so no need to worry here.
617 		 */
618 
619 		pisr_clear = pisr & ~AR5K_ISR_BITS_FROM_SISRS;
620 
621 		/*
622 		 * Write to clear them...
623 		 * Note: This means that each bit we write back
624 		 * to the registers will get cleared, leaving the
625 		 * rest unaffected. So this won't affect new interrupts
626 		 * we didn't catch while reading/processing, we 'll get
627 		 * them next time get_isr gets called.
628 		 */
629 		ath5k_hw_reg_write(ah, sisr0, AR5K_SISR0);
630 		ath5k_hw_reg_write(ah, sisr1, AR5K_SISR1);
631 		ath5k_hw_reg_write(ah, sisr2, AR5K_SISR2);
632 		ath5k_hw_reg_write(ah, sisr3, AR5K_SISR3);
633 		ath5k_hw_reg_write(ah, sisr4, AR5K_SISR4);
634 		ath5k_hw_reg_write(ah, pisr_clear, AR5K_PISR);
635 		/* Flush previous write */
636 		ath5k_hw_reg_read(ah, AR5K_PISR);
637 
638 		/*
639 		 * Filter out the non-common bits from the interrupt
640 		 * status.
641 		 */
642 		*interrupt_mask = (pisr & AR5K_INT_COMMON) & ah->ah_imr;
643 
644 
645 		/* We treat TXOK,TXDESC, TXERR and TXEOL
646 		 * the same way (schedule the tx tasklet)
647 		 * so we track them all together per queue */
648 		if (pisr & AR5K_ISR_TXOK)
649 			ah->ah_txq_isr_txok_all |= AR5K_REG_MS(sisr0,
650 						AR5K_SISR0_QCU_TXOK);
651 
652 		if (pisr & AR5K_ISR_TXDESC)
653 			ah->ah_txq_isr_txok_all |= AR5K_REG_MS(sisr0,
654 						AR5K_SISR0_QCU_TXDESC);
655 
656 		if (pisr & AR5K_ISR_TXERR)
657 			ah->ah_txq_isr_txok_all |= AR5K_REG_MS(sisr1,
658 						AR5K_SISR1_QCU_TXERR);
659 
660 		if (pisr & AR5K_ISR_TXEOL)
661 			ah->ah_txq_isr_txok_all |= AR5K_REG_MS(sisr1,
662 						AR5K_SISR1_QCU_TXEOL);
663 
664 		/* Currently this is not much useful since we treat
665 		 * all queues the same way if we get a TXURN (update
666 		 * tx trigger level) but we might need it later on*/
667 		if (pisr & AR5K_ISR_TXURN)
668 			ah->ah_txq_isr_txurn |= AR5K_REG_MS(sisr2,
669 						AR5K_SISR2_QCU_TXURN);
670 
671 		/* Misc Beacon related interrupts */
672 
673 		/* For AR5211 */
674 		if (pisr & AR5K_ISR_TIM)
675 			*interrupt_mask |= AR5K_INT_TIM;
676 
677 		/* For AR5212+ */
678 		if (pisr & AR5K_ISR_BCNMISC) {
679 			if (sisr2 & AR5K_SISR2_TIM)
680 				*interrupt_mask |= AR5K_INT_TIM;
681 			if (sisr2 & AR5K_SISR2_DTIM)
682 				*interrupt_mask |= AR5K_INT_DTIM;
683 			if (sisr2 & AR5K_SISR2_DTIM_SYNC)
684 				*interrupt_mask |= AR5K_INT_DTIM_SYNC;
685 			if (sisr2 & AR5K_SISR2_BCN_TIMEOUT)
686 				*interrupt_mask |= AR5K_INT_BCN_TIMEOUT;
687 			if (sisr2 & AR5K_SISR2_CAB_TIMEOUT)
688 				*interrupt_mask |= AR5K_INT_CAB_TIMEOUT;
689 		}
690 
691 		/* Below interrupts are unlikely to happen */
692 
693 		/* HIU = Host Interface Unit (PCI etc)
694 		 * Can be one of MCABT, SSERR, DPERR from SISR2 */
695 		if (unlikely(pisr & (AR5K_ISR_HIUERR)))
696 			*interrupt_mask |= AR5K_INT_FATAL;
697 
698 		/*Beacon Not Ready*/
699 		if (unlikely(pisr & (AR5K_ISR_BNR)))
700 			*interrupt_mask |= AR5K_INT_BNR;
701 
702 		/* A queue got CBR overrun */
703 		if (unlikely(pisr & (AR5K_ISR_QCBRORN))) {
704 			*interrupt_mask |= AR5K_INT_QCBRORN;
705 			ah->ah_txq_isr_qcborn |= AR5K_REG_MS(sisr3,
706 						AR5K_SISR3_QCBRORN);
707 		}
708 
709 		/* A queue got CBR underrun */
710 		if (unlikely(pisr & (AR5K_ISR_QCBRURN))) {
711 			*interrupt_mask |= AR5K_INT_QCBRURN;
712 			ah->ah_txq_isr_qcburn |= AR5K_REG_MS(sisr3,
713 						AR5K_SISR3_QCBRURN);
714 		}
715 
716 		/* A queue got triggered */
717 		if (unlikely(pisr & (AR5K_ISR_QTRIG))) {
718 			*interrupt_mask |= AR5K_INT_QTRIG;
719 			ah->ah_txq_isr_qtrig |= AR5K_REG_MS(sisr4,
720 						AR5K_SISR4_QTRIG);
721 		}
722 
723 		data = pisr;
724 	}
725 
726 	/*
727 	 * In case we didn't handle anything,
728 	 * print the register value.
729 	 */
730 	if (unlikely(*interrupt_mask == 0 && net_ratelimit()))
731 		ATH5K_PRINTF("ISR: 0x%08x IMR: 0x%08x\n", data, ah->ah_imr);
732 
733 	return 0;
734 }
735 
736 /**
737  * ath5k_hw_set_imr() - Set interrupt mask
738  * @ah: The &struct ath5k_hw
739  * @new_mask: The new interrupt mask to be set
740  *
741  * Set the interrupt mask in hw to save interrupts. We do that by mapping
742  * ath5k_int bits to hw-specific bits to remove abstraction and writing
743  * Interrupt Mask Register.
744  */
745 enum ath5k_int
746 ath5k_hw_set_imr(struct ath5k_hw *ah, enum ath5k_int new_mask)
747 {
748 	enum ath5k_int old_mask, int_mask;
749 
750 	old_mask = ah->ah_imr;
751 
752 	/*
753 	 * Disable card interrupts to prevent any race conditions
754 	 * (they will be re-enabled afterwards if AR5K_INT GLOBAL
755 	 * is set again on the new mask).
756 	 */
757 	if (old_mask & AR5K_INT_GLOBAL) {
758 		ath5k_hw_reg_write(ah, AR5K_IER_DISABLE, AR5K_IER);
759 		ath5k_hw_reg_read(ah, AR5K_IER);
760 	}
761 
762 	/*
763 	 * Add additional, chipset-dependent interrupt mask flags
764 	 * and write them to the IMR (interrupt mask register).
765 	 */
766 	int_mask = new_mask & AR5K_INT_COMMON;
767 
768 	if (ah->ah_version != AR5K_AR5210) {
769 		/* Preserve per queue TXURN interrupt mask */
770 		u32 simr2 = ath5k_hw_reg_read(ah, AR5K_SIMR2)
771 				& AR5K_SIMR2_QCU_TXURN;
772 
773 		/* Fatal interrupt abstraction for 5211+ */
774 		if (new_mask & AR5K_INT_FATAL) {
775 			int_mask |= AR5K_IMR_HIUERR;
776 			simr2 |= (AR5K_SIMR2_MCABT | AR5K_SIMR2_SSERR
777 				| AR5K_SIMR2_DPERR);
778 		}
779 
780 		/* Misc beacon related interrupts */
781 		if (new_mask & AR5K_INT_TIM)
782 			int_mask |= AR5K_IMR_TIM;
783 
784 		if (new_mask & AR5K_INT_TIM)
785 			simr2 |= AR5K_SISR2_TIM;
786 		if (new_mask & AR5K_INT_DTIM)
787 			simr2 |= AR5K_SISR2_DTIM;
788 		if (new_mask & AR5K_INT_DTIM_SYNC)
789 			simr2 |= AR5K_SISR2_DTIM_SYNC;
790 		if (new_mask & AR5K_INT_BCN_TIMEOUT)
791 			simr2 |= AR5K_SISR2_BCN_TIMEOUT;
792 		if (new_mask & AR5K_INT_CAB_TIMEOUT)
793 			simr2 |= AR5K_SISR2_CAB_TIMEOUT;
794 
795 		/*Beacon Not Ready*/
796 		if (new_mask & AR5K_INT_BNR)
797 			int_mask |= AR5K_INT_BNR;
798 
799 		/* Note: Per queue interrupt masks
800 		 * are set via ath5k_hw_reset_tx_queue() (qcu.c) */
801 		ath5k_hw_reg_write(ah, int_mask, AR5K_PIMR);
802 		ath5k_hw_reg_write(ah, simr2, AR5K_SIMR2);
803 
804 	} else {
805 		/* Fatal interrupt abstraction for 5210 */
806 		if (new_mask & AR5K_INT_FATAL)
807 			int_mask |= (AR5K_IMR_SSERR | AR5K_IMR_MCABT
808 				| AR5K_IMR_HIUERR | AR5K_IMR_DPERR);
809 
810 		/* Only common interrupts left for 5210 (no SIMRs) */
811 		ath5k_hw_reg_write(ah, int_mask, AR5K_IMR);
812 	}
813 
814 	/* If RXNOFRM interrupt is masked disable it
815 	 * by setting AR5K_RXNOFRM to zero */
816 	if (!(new_mask & AR5K_INT_RXNOFRM))
817 		ath5k_hw_reg_write(ah, 0, AR5K_RXNOFRM);
818 
819 	/* Store new interrupt mask */
820 	ah->ah_imr = new_mask;
821 
822 	/* ..re-enable interrupts if AR5K_INT_GLOBAL is set */
823 	if (new_mask & AR5K_INT_GLOBAL) {
824 		ath5k_hw_reg_write(ah, AR5K_IER_ENABLE, AR5K_IER);
825 		ath5k_hw_reg_read(ah, AR5K_IER);
826 	}
827 
828 	return old_mask;
829 }
830 
831 
832 /********************\
833  Init/Stop functions
834 \********************/
835 
836 /**
837  * ath5k_hw_dma_init() - Initialize DMA unit
838  * @ah: The &struct ath5k_hw
839  *
840  * Set DMA size and pre-enable interrupts
841  * (driver handles tx/rx buffer setup and
842  * dma start/stop)
843  *
844  * XXX: Save/restore RXDP/TXDP registers ?
845  */
846 void
847 ath5k_hw_dma_init(struct ath5k_hw *ah)
848 {
849 	/*
850 	 * Set Rx/Tx DMA Configuration
851 	 *
852 	 * Set standard DMA size (128). Note that
853 	 * a DMA size of 512 causes rx overruns and tx errors
854 	 * on pci-e cards (tested on 5424 but since rx overruns
855 	 * also occur on 5416/5418 with madwifi we set 128
856 	 * for all PCI-E cards to be safe).
857 	 *
858 	 * XXX: need to check 5210 for this
859 	 * TODO: Check out tx trigger level, it's always 64 on dumps but I
860 	 * guess we can tweak it and see how it goes ;-)
861 	 */
862 	if (ah->ah_version != AR5K_AR5210) {
863 		AR5K_REG_WRITE_BITS(ah, AR5K_TXCFG,
864 			AR5K_TXCFG_SDMAMR, AR5K_DMASIZE_128B);
865 		AR5K_REG_WRITE_BITS(ah, AR5K_RXCFG,
866 			AR5K_RXCFG_SDMAMW, AR5K_DMASIZE_128B);
867 	}
868 
869 	/* Pre-enable interrupts on 5211/5212*/
870 	if (ah->ah_version != AR5K_AR5210)
871 		ath5k_hw_set_imr(ah, ah->ah_imr);
872 
873 }
874 
875 /**
876  * ath5k_hw_dma_stop() - stop DMA unit
877  * @ah: The &struct ath5k_hw
878  *
879  * Stop tx/rx DMA and interrupts. Returns
880  * -EBUSY if tx or rx dma failed to stop.
881  *
882  * XXX: Sometimes DMA unit hangs and we have
883  * stuck frames on tx queues, only a reset
884  * can fix that.
885  */
886 int
887 ath5k_hw_dma_stop(struct ath5k_hw *ah)
888 {
889 	int i, qmax, err;
890 	err = 0;
891 
892 	/* Disable interrupts */
893 	ath5k_hw_set_imr(ah, 0);
894 
895 	/* Stop rx dma */
896 	err = ath5k_hw_stop_rx_dma(ah);
897 	if (err)
898 		return err;
899 
900 	/* Clear any pending interrupts
901 	 * and disable tx dma */
902 	if (ah->ah_version != AR5K_AR5210) {
903 		ath5k_hw_reg_write(ah, 0xffffffff, AR5K_PISR);
904 		qmax = AR5K_NUM_TX_QUEUES;
905 	} else {
906 		/* PISR/SISR Not available on 5210 */
907 		ath5k_hw_reg_read(ah, AR5K_ISR);
908 		qmax = AR5K_NUM_TX_QUEUES_NOQCU;
909 	}
910 
911 	for (i = 0; i < qmax; i++) {
912 		err = ath5k_hw_stop_tx_dma(ah, i);
913 		/* -EINVAL -> queue inactive */
914 		if (err && err != -EINVAL)
915 			return err;
916 	}
917 
918 	return 0;
919 }
920