2 * Freescale DMA ALSA SoC PCM driver
4 * Author: Timur Tabi <timur@freescale.com>
6 * Copyright 2007-2010 Freescale Semiconductor, Inc.
8 * This file is licensed under the terms of the GNU General Public License
9 * version 2. This program is licensed "as is" without any warranty of any
10 * kind, whether express or implied.
12 * This driver implements ASoC support for the Elo DMA controller, which is
13 * the DMA controller on Freescale 83xx, 85xx, and 86xx SOCs. In ALSA terms,
14 * the PCM driver is what handles the DMA buffer.
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/platform_device.h>
20 #include <linux/dma-mapping.h>
21 #include <linux/interrupt.h>
22 #include <linux/delay.h>
23 #include <linux/gfp.h>
24 #include <linux/of_platform.h>
25 #include <linux/list.h>
27 #include <sound/core.h>
28 #include <sound/pcm.h>
29 #include <sound/pcm_params.h>
30 #include <sound/soc.h>
35 #include "fsl_ssi.h" /* For the offset of stx0 and srx0 */
38 * The formats that the DMA controller supports, which is anything
39 * that is 8, 16, or 32 bits.
41 #define FSLDMA_PCM_FORMATS (SNDRV_PCM_FMTBIT_S8 | \
42 SNDRV_PCM_FMTBIT_U8 | \
43 SNDRV_PCM_FMTBIT_S16_LE | \
44 SNDRV_PCM_FMTBIT_S16_BE | \
45 SNDRV_PCM_FMTBIT_U16_LE | \
46 SNDRV_PCM_FMTBIT_U16_BE | \
47 SNDRV_PCM_FMTBIT_S24_LE | \
48 SNDRV_PCM_FMTBIT_S24_BE | \
49 SNDRV_PCM_FMTBIT_U24_LE | \
50 SNDRV_PCM_FMTBIT_U24_BE | \
51 SNDRV_PCM_FMTBIT_S32_LE | \
52 SNDRV_PCM_FMTBIT_S32_BE | \
53 SNDRV_PCM_FMTBIT_U32_LE | \
54 SNDRV_PCM_FMTBIT_U32_BE)
56 #define FSLDMA_PCM_RATES (SNDRV_PCM_RATE_5512 | SNDRV_PCM_RATE_8000_192000 | \
57 SNDRV_PCM_RATE_CONTINUOUS)
60 struct list_head list;
61 struct snd_soc_platform_driver dai;
62 dma_addr_t ssi_stx_phys;
63 dma_addr_t ssi_srx_phys;
64 struct ccsr_dma_channel __iomem *channel;
71 * The number of DMA links to use. Two is the bare minimum, but if you
72 * have really small links you might need more.
74 #define NUM_DMA_LINKS 2
76 /** fsl_dma_private: p-substream DMA data
78 * Each substream has a 1-to-1 association with a DMA channel.
80 * The link[] array is first because it needs to be aligned on a 32-byte
81 * boundary, so putting it first will ensure alignment without padding the
84 * @link[]: array of link descriptors
85 * @dma_channel: pointer to the DMA channel's registers
86 * @irq: IRQ for this DMA channel
87 * @substream: pointer to the substream object, needed by the ISR
88 * @ssi_sxx_phys: bus address of the STX or SRX register to use
89 * @ld_buf_phys: physical address of the LD buffer
90 * @current_link: index into link[] of the link currently being processed
91 * @dma_buf_phys: physical address of the DMA buffer
92 * @dma_buf_next: physical address of the next period to process
93 * @dma_buf_end: physical address of the byte after the end of the DMA
94 * @buffer period_size: the size of a single period
95 * @num_periods: the number of periods in the DMA buffer
97 struct fsl_dma_private {
98 struct fsl_dma_link_descriptor link[NUM_DMA_LINKS];
99 struct ccsr_dma_channel __iomem *dma_channel;
101 struct snd_pcm_substream *substream;
102 dma_addr_t ssi_sxx_phys;
103 dma_addr_t ld_buf_phys;
104 unsigned int current_link;
105 dma_addr_t dma_buf_phys;
106 dma_addr_t dma_buf_next;
107 dma_addr_t dma_buf_end;
109 unsigned int num_periods;
113 * fsl_dma_hardare: define characteristics of the PCM hardware.
115 * The PCM hardware is the Freescale DMA controller. This structure defines
116 * the capabilities of that hardware.
118 * Since the sampling rate and data format are not controlled by the DMA
119 * controller, we specify no limits for those values. The only exception is
120 * period_bytes_min, which is set to a reasonably low value to prevent the
121 * DMA controller from generating too many interrupts per second.
123 * Since each link descriptor has a 32-bit byte count field, we set
124 * period_bytes_max to the largest 32-bit number. We also have no maximum
127 * Note that we specify SNDRV_PCM_INFO_JOINT_DUPLEX here, but only because a
128 * limitation in the SSI driver requires the sample rates for playback and
129 * capture to be the same.
131 static const struct snd_pcm_hardware fsl_dma_hardware = {
133 .info = SNDRV_PCM_INFO_INTERLEAVED |
134 SNDRV_PCM_INFO_MMAP |
135 SNDRV_PCM_INFO_MMAP_VALID |
136 SNDRV_PCM_INFO_JOINT_DUPLEX |
137 SNDRV_PCM_INFO_PAUSE,
138 .formats = FSLDMA_PCM_FORMATS,
139 .rates = FSLDMA_PCM_RATES,
142 .period_bytes_min = 512, /* A reasonable limit */
143 .period_bytes_max = (u32) -1,
144 .periods_min = NUM_DMA_LINKS,
145 .periods_max = (unsigned int) -1,
146 .buffer_bytes_max = 128 * 1024, /* A reasonable limit */
150 * fsl_dma_abort_stream: tell ALSA that the DMA transfer has aborted
152 * This function should be called by the ISR whenever the DMA controller
153 * halts data transfer.
155 static void fsl_dma_abort_stream(struct snd_pcm_substream *substream)
159 snd_pcm_stream_lock_irqsave(substream, flags);
161 if (snd_pcm_running(substream))
162 snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
164 snd_pcm_stream_unlock_irqrestore(substream, flags);
168 * fsl_dma_update_pointers - update LD pointers to point to the next period
170 * As each period is completed, this function changes the the link
171 * descriptor pointers for that period to point to the next period.
173 static void fsl_dma_update_pointers(struct fsl_dma_private *dma_private)
175 struct fsl_dma_link_descriptor *link =
176 &dma_private->link[dma_private->current_link];
178 /* Update our link descriptors to point to the next period */
179 if (dma_private->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
181 cpu_to_be32(dma_private->dma_buf_next);
184 cpu_to_be32(dma_private->dma_buf_next);
186 /* Update our variables for next time */
187 dma_private->dma_buf_next += dma_private->period_size;
189 if (dma_private->dma_buf_next >= dma_private->dma_buf_end)
190 dma_private->dma_buf_next = dma_private->dma_buf_phys;
192 if (++dma_private->current_link >= NUM_DMA_LINKS)
193 dma_private->current_link = 0;
197 * fsl_dma_isr: interrupt handler for the DMA controller
199 * @irq: IRQ of the DMA channel
200 * @dev_id: pointer to the dma_private structure for this DMA channel
202 static irqreturn_t fsl_dma_isr(int irq, void *dev_id)
204 struct fsl_dma_private *dma_private = dev_id;
205 struct snd_pcm_substream *substream = dma_private->substream;
206 struct snd_soc_pcm_runtime *rtd = substream->private_data;
207 struct device *dev = rtd->platform->dev;
208 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
209 irqreturn_t ret = IRQ_NONE;
212 /* We got an interrupt, so read the status register to see what we
213 were interrupted for.
215 sr = in_be32(&dma_channel->sr);
217 if (sr & CCSR_DMA_SR_TE) {
218 dev_err(dev, "dma transmit error\n");
219 fsl_dma_abort_stream(substream);
220 sr2 |= CCSR_DMA_SR_TE;
224 if (sr & CCSR_DMA_SR_CH)
227 if (sr & CCSR_DMA_SR_PE) {
228 dev_err(dev, "dma programming error\n");
229 fsl_dma_abort_stream(substream);
230 sr2 |= CCSR_DMA_SR_PE;
234 if (sr & CCSR_DMA_SR_EOLNI) {
235 sr2 |= CCSR_DMA_SR_EOLNI;
239 if (sr & CCSR_DMA_SR_CB)
242 if (sr & CCSR_DMA_SR_EOSI) {
243 /* Tell ALSA we completed a period. */
244 snd_pcm_period_elapsed(substream);
247 * Update our link descriptors to point to the next period. We
248 * only need to do this if the number of periods is not equal to
249 * the number of links.
251 if (dma_private->num_periods != NUM_DMA_LINKS)
252 fsl_dma_update_pointers(dma_private);
254 sr2 |= CCSR_DMA_SR_EOSI;
258 if (sr & CCSR_DMA_SR_EOLSI) {
259 sr2 |= CCSR_DMA_SR_EOLSI;
263 /* Clear the bits that we set */
265 out_be32(&dma_channel->sr, sr2);
271 * fsl_dma_new: initialize this PCM driver.
273 * This function is called when the codec driver calls snd_soc_new_pcms(),
274 * once for each .dai_link in the machine driver's snd_soc_card
277 static int fsl_dma_new(struct snd_card *card, struct snd_soc_dai *dai,
280 static u64 fsl_dma_dmamask = DMA_BIT_MASK(32);
283 if (!card->dev->dma_mask)
284 card->dev->dma_mask = &fsl_dma_dmamask;
286 if (!card->dev->coherent_dma_mask)
287 card->dev->coherent_dma_mask = fsl_dma_dmamask;
289 ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, card->dev,
290 fsl_dma_hardware.buffer_bytes_max,
291 &pcm->streams[0].substream->dma_buffer);
293 dev_err(card->dev, "can't allocate playback dma buffer\n");
297 ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, card->dev,
298 fsl_dma_hardware.buffer_bytes_max,
299 &pcm->streams[1].substream->dma_buffer);
301 snd_dma_free_pages(&pcm->streams[0].substream->dma_buffer);
302 dev_err(card->dev, "can't allocate capture dma buffer\n");
310 * fsl_dma_open: open a new substream.
312 * Each substream has its own DMA buffer.
314 * ALSA divides the DMA buffer into N periods. We create NUM_DMA_LINKS link
315 * descriptors that ping-pong from one period to the next. For example, if
316 * there are six periods and two link descriptors, this is how they look
317 * before playback starts:
319 * The last link descriptor
320 * ____________ points back to the first
329 * _________________________________________
330 * | | | | | | | The DMA buffer is
331 * | | | | | | | divided into 6 parts
332 * |______|______|______|______|______|______|
334 * and here's how they look after the first period is finished playing:
346 * _________________________________________
349 * |______|______|______|______|______|______|
351 * The first link descriptor now points to the third period. The DMA
352 * controller is currently playing the second period. When it finishes, it
353 * will jump back to the first descriptor and play the third period.
355 * There are four reasons we do this:
357 * 1. The only way to get the DMA controller to automatically restart the
358 * transfer when it gets to the end of the buffer is to use chaining
359 * mode. Basic direct mode doesn't offer that feature.
360 * 2. We need to receive an interrupt at the end of every period. The DMA
361 * controller can generate an interrupt at the end of every link transfer
362 * (aka segment). Making each period into a DMA segment will give us the
363 * interrupts we need.
364 * 3. By creating only two link descriptors, regardless of the number of
365 * periods, we do not need to reallocate the link descriptors if the
366 * number of periods changes.
367 * 4. All of the audio data is still stored in a single, contiguous DMA
368 * buffer, which is what ALSA expects. We're just dividing it into
369 * contiguous parts, and creating a link descriptor for each one.
371 static int fsl_dma_open(struct snd_pcm_substream *substream)
373 struct snd_pcm_runtime *runtime = substream->runtime;
374 struct snd_soc_pcm_runtime *rtd = substream->private_data;
375 struct device *dev = rtd->platform->dev;
376 struct dma_object *dma =
377 container_of(rtd->platform->driver, struct dma_object, dai);
378 struct fsl_dma_private *dma_private;
379 struct ccsr_dma_channel __iomem *dma_channel;
380 dma_addr_t ld_buf_phys;
381 u64 temp_link; /* Pointer to next link descriptor */
383 unsigned int channel;
388 * Reject any DMA buffer whose size is not a multiple of the period
389 * size. We need to make sure that the DMA buffer can be evenly divided
392 ret = snd_pcm_hw_constraint_integer(runtime,
393 SNDRV_PCM_HW_PARAM_PERIODS);
395 dev_err(dev, "invalid buffer size\n");
399 channel = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1;
402 dev_err(dev, "dma channel already assigned\n");
406 dma_private = dma_alloc_coherent(dev, sizeof(struct fsl_dma_private),
407 &ld_buf_phys, GFP_KERNEL);
409 dev_err(dev, "can't allocate dma private data\n");
412 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
413 dma_private->ssi_sxx_phys = dma->ssi_stx_phys;
415 dma_private->ssi_sxx_phys = dma->ssi_srx_phys;
417 dma_private->dma_channel = dma->channel;
418 dma_private->irq = dma->irq;
419 dma_private->substream = substream;
420 dma_private->ld_buf_phys = ld_buf_phys;
421 dma_private->dma_buf_phys = substream->dma_buffer.addr;
423 ret = request_irq(dma_private->irq, fsl_dma_isr, 0, "DMA", dma_private);
425 dev_err(dev, "can't register ISR for IRQ %u (ret=%i)\n",
426 dma_private->irq, ret);
427 dma_free_coherent(dev, sizeof(struct fsl_dma_private),
428 dma_private, dma_private->ld_buf_phys);
434 snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
435 snd_soc_set_runtime_hwparams(substream, &fsl_dma_hardware);
436 runtime->private_data = dma_private;
438 /* Program the fixed DMA controller parameters */
440 dma_channel = dma_private->dma_channel;
442 temp_link = dma_private->ld_buf_phys +
443 sizeof(struct fsl_dma_link_descriptor);
445 for (i = 0; i < NUM_DMA_LINKS; i++) {
446 dma_private->link[i].next = cpu_to_be64(temp_link);
448 temp_link += sizeof(struct fsl_dma_link_descriptor);
450 /* The last link descriptor points to the first */
451 dma_private->link[i - 1].next = cpu_to_be64(dma_private->ld_buf_phys);
453 /* Tell the DMA controller where the first link descriptor is */
454 out_be32(&dma_channel->clndar,
455 CCSR_DMA_CLNDAR_ADDR(dma_private->ld_buf_phys));
456 out_be32(&dma_channel->eclndar,
457 CCSR_DMA_ECLNDAR_ADDR(dma_private->ld_buf_phys));
459 /* The manual says the BCR must be clear before enabling EMP */
460 out_be32(&dma_channel->bcr, 0);
463 * Program the mode register for interrupts, external master control,
464 * and source/destination hold. Also clear the Channel Abort bit.
466 mr = in_be32(&dma_channel->mr) &
467 ~(CCSR_DMA_MR_CA | CCSR_DMA_MR_DAHE | CCSR_DMA_MR_SAHE);
470 * We want External Master Start and External Master Pause enabled,
471 * because the SSI is controlling the DMA controller. We want the DMA
472 * controller to be set up in advance, and then we signal only the SSI
473 * to start transferring.
475 * We want End-Of-Segment Interrupts enabled, because this will generate
476 * an interrupt at the end of each segment (each link descriptor
477 * represents one segment). Each DMA segment is the same thing as an
478 * ALSA period, so this is how we get an interrupt at the end of every
481 * We want Error Interrupt enabled, so that we can get an error if
482 * the DMA controller is mis-programmed somehow.
484 mr |= CCSR_DMA_MR_EOSIE | CCSR_DMA_MR_EIE | CCSR_DMA_MR_EMP_EN |
487 /* For playback, we want the destination address to be held. For
488 capture, set the source address to be held. */
489 mr |= (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
490 CCSR_DMA_MR_DAHE : CCSR_DMA_MR_SAHE;
492 out_be32(&dma_channel->mr, mr);
498 * fsl_dma_hw_params: continue initializing the DMA links
500 * This function obtains hardware parameters about the opened stream and
501 * programs the DMA controller accordingly.
503 * One drawback of big-endian is that when copying integers of different
504 * sizes to a fixed-sized register, the address to which the integer must be
505 * copied is dependent on the size of the integer.
507 * For example, if P is the address of a 32-bit register, and X is a 32-bit
508 * integer, then X should be copied to address P. However, if X is a 16-bit
509 * integer, then it should be copied to P+2. If X is an 8-bit register,
510 * then it should be copied to P+3.
512 * So for playback of 8-bit samples, the DMA controller must transfer single
513 * bytes from the DMA buffer to the last byte of the STX0 register, i.e.
514 * offset by 3 bytes. For 16-bit samples, the offset is two bytes.
516 * For 24-bit samples, the offset is 1 byte. However, the DMA controller
517 * does not support 3-byte copies (the DAHTS register supports only 1, 2, 4,
518 * and 8 bytes at a time). So we do not support packed 24-bit samples.
519 * 24-bit data must be padded to 32 bits.
521 static int fsl_dma_hw_params(struct snd_pcm_substream *substream,
522 struct snd_pcm_hw_params *hw_params)
524 struct snd_pcm_runtime *runtime = substream->runtime;
525 struct fsl_dma_private *dma_private = runtime->private_data;
526 struct snd_soc_pcm_runtime *rtd = substream->private_data;
527 struct device *dev = rtd->platform->dev;
529 /* Number of bits per sample */
530 unsigned int sample_size =
531 snd_pcm_format_physical_width(params_format(hw_params));
533 /* Number of bytes per frame */
534 unsigned int frame_size = 2 * (sample_size / 8);
536 /* Bus address of SSI STX register */
537 dma_addr_t ssi_sxx_phys = dma_private->ssi_sxx_phys;
539 /* Size of the DMA buffer, in bytes */
540 size_t buffer_size = params_buffer_bytes(hw_params);
542 /* Number of bytes per period */
543 size_t period_size = params_period_bytes(hw_params);
545 /* Pointer to next period */
546 dma_addr_t temp_addr = substream->dma_buffer.addr;
548 /* Pointer to DMA controller */
549 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
551 u32 mr; /* DMA Mode Register */
555 /* Initialize our DMA tracking variables */
556 dma_private->period_size = period_size;
557 dma_private->num_periods = params_periods(hw_params);
558 dma_private->dma_buf_end = dma_private->dma_buf_phys + buffer_size;
559 dma_private->dma_buf_next = dma_private->dma_buf_phys +
560 (NUM_DMA_LINKS * period_size);
562 if (dma_private->dma_buf_next >= dma_private->dma_buf_end)
563 /* This happens if the number of periods == NUM_DMA_LINKS */
564 dma_private->dma_buf_next = dma_private->dma_buf_phys;
566 mr = in_be32(&dma_channel->mr) & ~(CCSR_DMA_MR_BWC_MASK |
567 CCSR_DMA_MR_SAHTS_MASK | CCSR_DMA_MR_DAHTS_MASK);
569 /* Due to a quirk of the SSI's STX register, the target address
570 * for the DMA operations depends on the sample size. So we calculate
571 * that offset here. While we're at it, also tell the DMA controller
572 * how much data to transfer per sample.
574 switch (sample_size) {
576 mr |= CCSR_DMA_MR_DAHTS_1 | CCSR_DMA_MR_SAHTS_1;
580 mr |= CCSR_DMA_MR_DAHTS_2 | CCSR_DMA_MR_SAHTS_2;
584 mr |= CCSR_DMA_MR_DAHTS_4 | CCSR_DMA_MR_SAHTS_4;
587 /* We should never get here */
588 dev_err(dev, "unsupported sample size %u\n", sample_size);
593 * BWC should always be a multiple of the frame size. BWC determines
594 * how many bytes are sent/received before the DMA controller checks the
595 * SSI to see if it needs to stop. For playback, the transmit FIFO can
596 * hold three frames, so we want to send two frames at a time. For
597 * capture, the receive FIFO is triggered when it contains one frame, so
598 * we want to receive one frame at a time.
600 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
601 mr |= CCSR_DMA_MR_BWC(2 * frame_size);
603 mr |= CCSR_DMA_MR_BWC(frame_size);
605 out_be32(&dma_channel->mr, mr);
607 for (i = 0; i < NUM_DMA_LINKS; i++) {
608 struct fsl_dma_link_descriptor *link = &dma_private->link[i];
610 link->count = cpu_to_be32(period_size);
612 /* Even though the DMA controller supports 36-bit addressing,
613 * for simplicity we allow only 32-bit addresses for the audio
614 * buffer itself. This was enforced in fsl_dma_new() with the
617 * The snoop bit tells the DMA controller whether it should tell
618 * the ECM to snoop during a read or write to an address. For
619 * audio, we use DMA to transfer data between memory and an I/O
620 * device (the SSI's STX0 or SRX0 register). Snooping is only
621 * needed if there is a cache, so we need to snoop memory
622 * addresses only. For playback, that means we snoop the source
623 * but not the destination. For capture, we snoop the
624 * destination but not the source.
626 * Note that failing to snoop properly is unlikely to cause
627 * cache incoherency if the period size is larger than the
628 * size of L1 cache. This is because filling in one period will
629 * flush out the data for the previous period. So if you
630 * increased period_bytes_min to a large enough size, you might
631 * get more performance by not snooping, and you'll still be
634 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
635 link->source_addr = cpu_to_be32(temp_addr);
636 link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);
638 link->dest_addr = cpu_to_be32(ssi_sxx_phys);
639 link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP);
641 link->source_addr = cpu_to_be32(ssi_sxx_phys);
642 link->source_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP);
644 link->dest_addr = cpu_to_be32(temp_addr);
645 link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);
648 temp_addr += period_size;
655 * fsl_dma_pointer: determine the current position of the DMA transfer
657 * This function is called by ALSA when ALSA wants to know where in the
658 * stream buffer the hardware currently is.
660 * For playback, the SAR register contains the physical address of the most
661 * recent DMA transfer. For capture, the value is in the DAR register.
663 * The base address of the buffer is stored in the source_addr field of the
664 * first link descriptor.
666 static snd_pcm_uframes_t fsl_dma_pointer(struct snd_pcm_substream *substream)
668 struct snd_pcm_runtime *runtime = substream->runtime;
669 struct fsl_dma_private *dma_private = runtime->private_data;
670 struct snd_soc_pcm_runtime *rtd = substream->private_data;
671 struct device *dev = rtd->platform->dev;
672 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
674 snd_pcm_uframes_t frames;
676 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
677 position = in_be32(&dma_channel->sar);
679 position = in_be32(&dma_channel->dar);
682 * When capture is started, the SSI immediately starts to fill its FIFO.
683 * This means that the DMA controller is not started until the FIFO is
684 * full. However, ALSA calls this function before that happens, when
685 * MR.DAR is still zero. In this case, just return zero to indicate
686 * that nothing has been received yet.
691 if ((position < dma_private->dma_buf_phys) ||
692 (position > dma_private->dma_buf_end)) {
693 dev_err(dev, "dma pointer is out of range, halting stream\n");
694 return SNDRV_PCM_POS_XRUN;
697 frames = bytes_to_frames(runtime, position - dma_private->dma_buf_phys);
700 * If the current address is just past the end of the buffer, wrap it
703 if (frames == runtime->buffer_size)
710 * fsl_dma_hw_free: release resources allocated in fsl_dma_hw_params()
712 * Release the resources allocated in fsl_dma_hw_params() and de-program the
715 * This function can be called multiple times.
717 static int fsl_dma_hw_free(struct snd_pcm_substream *substream)
719 struct snd_pcm_runtime *runtime = substream->runtime;
720 struct fsl_dma_private *dma_private = runtime->private_data;
723 struct ccsr_dma_channel __iomem *dma_channel;
725 dma_channel = dma_private->dma_channel;
728 out_be32(&dma_channel->mr, CCSR_DMA_MR_CA);
729 out_be32(&dma_channel->mr, 0);
731 /* Reset all the other registers */
732 out_be32(&dma_channel->sr, -1);
733 out_be32(&dma_channel->clndar, 0);
734 out_be32(&dma_channel->eclndar, 0);
735 out_be32(&dma_channel->satr, 0);
736 out_be32(&dma_channel->sar, 0);
737 out_be32(&dma_channel->datr, 0);
738 out_be32(&dma_channel->dar, 0);
739 out_be32(&dma_channel->bcr, 0);
740 out_be32(&dma_channel->nlndar, 0);
741 out_be32(&dma_channel->enlndar, 0);
748 * fsl_dma_close: close the stream.
750 static int fsl_dma_close(struct snd_pcm_substream *substream)
752 struct snd_pcm_runtime *runtime = substream->runtime;
753 struct fsl_dma_private *dma_private = runtime->private_data;
754 struct snd_soc_pcm_runtime *rtd = substream->private_data;
755 struct device *dev = rtd->platform->dev;
756 struct dma_object *dma =
757 container_of(rtd->platform->driver, struct dma_object, dai);
760 if (dma_private->irq)
761 free_irq(dma_private->irq, dma_private);
763 if (dma_private->ld_buf_phys) {
764 dma_unmap_single(dev, dma_private->ld_buf_phys,
765 sizeof(dma_private->link),
769 /* Deallocate the fsl_dma_private structure */
770 dma_free_coherent(dev, sizeof(struct fsl_dma_private),
771 dma_private, dma_private->ld_buf_phys);
772 substream->runtime->private_data = NULL;
781 * Remove this PCM driver.
783 static void fsl_dma_free_dma_buffers(struct snd_pcm *pcm)
785 struct snd_pcm_substream *substream;
788 for (i = 0; i < ARRAY_SIZE(pcm->streams); i++) {
789 substream = pcm->streams[i].substream;
791 snd_dma_free_pages(&substream->dma_buffer);
792 substream->dma_buffer.area = NULL;
793 substream->dma_buffer.addr = 0;
798 /* List of DMA nodes that we've probed */
799 static LIST_HEAD(dma_list);
802 * find_ssi_node -- returns the SSI node that points to his DMA channel node
804 * Although this DMA driver attempts to operate independently of the other
805 * devices, it still needs to determine some information about the SSI device
806 * that it's working with. Unfortunately, the device tree does not contain
807 * a pointer from the DMA channel node to the SSI node -- the pointer goes the
808 * other way. So we need to scan the device tree for SSI nodes until we find
809 * the one that points to the given DMA channel node. It's ugly, but at least
810 * it's contained in this one function.
812 static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
814 struct device_node *ssi_np, *np;
816 for_each_compatible_node(ssi_np, NULL, "fsl,mpc8610-ssi") {
817 /* Check each DMA phandle to see if it points to us. We
818 * assume that device_node pointers are a valid comparison.
820 np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
821 if (np == dma_channel_np)
824 np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
825 if (np == dma_channel_np)
832 static struct snd_pcm_ops fsl_dma_ops = {
833 .open = fsl_dma_open,
834 .close = fsl_dma_close,
835 .ioctl = snd_pcm_lib_ioctl,
836 .hw_params = fsl_dma_hw_params,
837 .hw_free = fsl_dma_hw_free,
838 .pointer = fsl_dma_pointer,
841 static int __devinit fsl_soc_dma_probe(struct of_device *of_dev,
842 const struct of_device_id *match)
844 struct dma_object *dma;
845 struct device_node *np = of_dev->dev.of_node;
846 struct device_node *ssi_np;
850 /* Find the SSI node that points to us. */
851 ssi_np = find_ssi_node(np);
853 dev_err(&of_dev->dev, "cannot find parent SSI node\n");
857 ret = of_address_to_resource(ssi_np, 0, &res);
860 dev_err(&of_dev->dev, "could not determine device resources\n");
864 dma = kzalloc(sizeof(*dma) + strlen(np->full_name), GFP_KERNEL);
866 dev_err(&of_dev->dev, "could not allocate dma object\n");
870 strcpy(dma->path, np->full_name);
871 dma->dai.ops = &fsl_dma_ops;
872 dma->dai.pcm_new = fsl_dma_new;
873 dma->dai.pcm_free = fsl_dma_free_dma_buffers;
875 /* Store the SSI-specific information that we need */
876 dma->ssi_stx_phys = res.start + offsetof(struct ccsr_ssi, stx0);
877 dma->ssi_srx_phys = res.start + offsetof(struct ccsr_ssi, srx0);
879 ret = snd_soc_register_platform(&of_dev->dev, &dma->dai);
881 dev_err(&of_dev->dev, "could not register platform\n");
886 dma->channel = of_iomap(np, 0);
887 dma->irq = irq_of_parse_and_map(np, 0);
888 list_add(&dma->list, &dma_list);
893 static int __devexit fsl_soc_dma_remove(struct of_device *of_dev)
895 struct list_head *n, *ptr;
896 struct dma_object *dma;
898 list_for_each_safe(ptr, n, &dma_list) {
899 dma = list_entry(ptr, struct dma_object, list);
902 snd_soc_unregister_platform(&of_dev->dev);
903 iounmap(dma->channel);
904 irq_dispose_mapping(dma->irq);
911 static const struct of_device_id fsl_soc_dma_ids[] = {
912 { .compatible = "fsl,ssi-dma-channel", },
915 MODULE_DEVICE_TABLE(of, fsl_soc_dma_ids);
917 static struct of_platform_driver fsl_soc_dma_driver = {
919 .name = "fsl-pcm-audio",
920 .owner = THIS_MODULE,
921 .of_match_table = fsl_soc_dma_ids,
923 .probe = fsl_soc_dma_probe,
924 .remove = __devexit_p(fsl_soc_dma_remove),
927 static int __init fsl_soc_dma_init(void)
929 pr_info("Freescale Elo DMA ASoC PCM Driver\n");
931 return of_register_platform_driver(&fsl_soc_dma_driver);
934 static void __exit fsl_soc_dma_exit(void)
936 of_unregister_platform_driver(&fsl_soc_dma_driver);
939 /* We want the DMA driver to be initialized before the SSI driver, so that
940 * when the SSI driver calls fsl_soc_dma_dai_from_node(), the DMA driver
941 * will already have been probed. The easiest way to do that is to make the
942 * __init function called via arch_initcall().
944 module_init(fsl_soc_dma_init);
945 module_exit(fsl_soc_dma_exit);
947 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
948 MODULE_DESCRIPTION("Freescale Elo DMA ASoC PCM Driver");
949 MODULE_LICENSE("GPL v2");