1 /* 2 * Freescale DMA ALSA SoC PCM driver 3 * 4 * Author: Timur Tabi <timur@freescale.com> 5 * 6 * Copyright 2007-2010 Freescale Semiconductor, Inc. 7 * 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. 11 * 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. 15 */ 16 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> 26 #include <linux/slab.h> 27 28 #include <sound/core.h> 29 #include <sound/pcm.h> 30 #include <sound/pcm_params.h> 31 #include <sound/soc.h> 32 33 #include <asm/io.h> 34 35 #include "fsl_dma.h" 36 #include "fsl_ssi.h" /* For the offset of stx0 and srx0 */ 37 38 /* 39 * The formats that the DMA controller supports, which is anything 40 * that is 8, 16, or 32 bits. 41 */ 42 #define FSLDMA_PCM_FORMATS (SNDRV_PCM_FMTBIT_S8 | \ 43 SNDRV_PCM_FMTBIT_U8 | \ 44 SNDRV_PCM_FMTBIT_S16_LE | \ 45 SNDRV_PCM_FMTBIT_S16_BE | \ 46 SNDRV_PCM_FMTBIT_U16_LE | \ 47 SNDRV_PCM_FMTBIT_U16_BE | \ 48 SNDRV_PCM_FMTBIT_S24_LE | \ 49 SNDRV_PCM_FMTBIT_S24_BE | \ 50 SNDRV_PCM_FMTBIT_U24_LE | \ 51 SNDRV_PCM_FMTBIT_U24_BE | \ 52 SNDRV_PCM_FMTBIT_S32_LE | \ 53 SNDRV_PCM_FMTBIT_S32_BE | \ 54 SNDRV_PCM_FMTBIT_U32_LE | \ 55 SNDRV_PCM_FMTBIT_U32_BE) 56 57 #define FSLDMA_PCM_RATES (SNDRV_PCM_RATE_5512 | SNDRV_PCM_RATE_8000_192000 | \ 58 SNDRV_PCM_RATE_CONTINUOUS) 59 60 struct dma_object { 61 struct snd_soc_platform_driver dai; 62 dma_addr_t ssi_stx_phys; 63 dma_addr_t ssi_srx_phys; 64 unsigned int ssi_fifo_depth; 65 struct ccsr_dma_channel __iomem *channel; 66 unsigned int irq; 67 bool assigned; 68 char path[1]; 69 }; 70 71 /* 72 * The number of DMA links to use. Two is the bare minimum, but if you 73 * have really small links you might need more. 74 */ 75 #define NUM_DMA_LINKS 2 76 77 /** fsl_dma_private: p-substream DMA data 78 * 79 * Each substream has a 1-to-1 association with a DMA channel. 80 * 81 * The link[] array is first because it needs to be aligned on a 32-byte 82 * boundary, so putting it first will ensure alignment without padding the 83 * structure. 84 * 85 * @link[]: array of link descriptors 86 * @dma_channel: pointer to the DMA channel's registers 87 * @irq: IRQ for this DMA channel 88 * @substream: pointer to the substream object, needed by the ISR 89 * @ssi_sxx_phys: bus address of the STX or SRX register to use 90 * @ld_buf_phys: physical address of the LD buffer 91 * @current_link: index into link[] of the link currently being processed 92 * @dma_buf_phys: physical address of the DMA buffer 93 * @dma_buf_next: physical address of the next period to process 94 * @dma_buf_end: physical address of the byte after the end of the DMA 95 * @buffer period_size: the size of a single period 96 * @num_periods: the number of periods in the DMA buffer 97 */ 98 struct fsl_dma_private { 99 struct fsl_dma_link_descriptor link[NUM_DMA_LINKS]; 100 struct ccsr_dma_channel __iomem *dma_channel; 101 unsigned int irq; 102 struct snd_pcm_substream *substream; 103 dma_addr_t ssi_sxx_phys; 104 unsigned int ssi_fifo_depth; 105 dma_addr_t ld_buf_phys; 106 unsigned int current_link; 107 dma_addr_t dma_buf_phys; 108 dma_addr_t dma_buf_next; 109 dma_addr_t dma_buf_end; 110 size_t period_size; 111 unsigned int num_periods; 112 }; 113 114 /** 115 * fsl_dma_hardare: define characteristics of the PCM hardware. 116 * 117 * The PCM hardware is the Freescale DMA controller. This structure defines 118 * the capabilities of that hardware. 119 * 120 * Since the sampling rate and data format are not controlled by the DMA 121 * controller, we specify no limits for those values. The only exception is 122 * period_bytes_min, which is set to a reasonably low value to prevent the 123 * DMA controller from generating too many interrupts per second. 124 * 125 * Since each link descriptor has a 32-bit byte count field, we set 126 * period_bytes_max to the largest 32-bit number. We also have no maximum 127 * number of periods. 128 * 129 * Note that we specify SNDRV_PCM_INFO_JOINT_DUPLEX here, but only because a 130 * limitation in the SSI driver requires the sample rates for playback and 131 * capture to be the same. 132 */ 133 static const struct snd_pcm_hardware fsl_dma_hardware = { 134 135 .info = SNDRV_PCM_INFO_INTERLEAVED | 136 SNDRV_PCM_INFO_MMAP | 137 SNDRV_PCM_INFO_MMAP_VALID | 138 SNDRV_PCM_INFO_JOINT_DUPLEX | 139 SNDRV_PCM_INFO_PAUSE, 140 .formats = FSLDMA_PCM_FORMATS, 141 .rates = FSLDMA_PCM_RATES, 142 .rate_min = 5512, 143 .rate_max = 192000, 144 .period_bytes_min = 512, /* A reasonable limit */ 145 .period_bytes_max = (u32) -1, 146 .periods_min = NUM_DMA_LINKS, 147 .periods_max = (unsigned int) -1, 148 .buffer_bytes_max = 128 * 1024, /* A reasonable limit */ 149 }; 150 151 /** 152 * fsl_dma_abort_stream: tell ALSA that the DMA transfer has aborted 153 * 154 * This function should be called by the ISR whenever the DMA controller 155 * halts data transfer. 156 */ 157 static void fsl_dma_abort_stream(struct snd_pcm_substream *substream) 158 { 159 unsigned long flags; 160 161 snd_pcm_stream_lock_irqsave(substream, flags); 162 163 if (snd_pcm_running(substream)) 164 snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN); 165 166 snd_pcm_stream_unlock_irqrestore(substream, flags); 167 } 168 169 /** 170 * fsl_dma_update_pointers - update LD pointers to point to the next period 171 * 172 * As each period is completed, this function changes the the link 173 * descriptor pointers for that period to point to the next period. 174 */ 175 static void fsl_dma_update_pointers(struct fsl_dma_private *dma_private) 176 { 177 struct fsl_dma_link_descriptor *link = 178 &dma_private->link[dma_private->current_link]; 179 180 /* Update our link descriptors to point to the next period. On a 36-bit 181 * system, we also need to update the ESAD bits. We also set (keep) the 182 * snoop bits. See the comments in fsl_dma_hw_params() about snooping. 183 */ 184 if (dma_private->substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { 185 link->source_addr = cpu_to_be32(dma_private->dma_buf_next); 186 #ifdef CONFIG_PHYS_64BIT 187 link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP | 188 upper_32_bits(dma_private->dma_buf_next)); 189 #endif 190 } else { 191 link->dest_addr = cpu_to_be32(dma_private->dma_buf_next); 192 #ifdef CONFIG_PHYS_64BIT 193 link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP | 194 upper_32_bits(dma_private->dma_buf_next)); 195 #endif 196 } 197 198 /* Update our variables for next time */ 199 dma_private->dma_buf_next += dma_private->period_size; 200 201 if (dma_private->dma_buf_next >= dma_private->dma_buf_end) 202 dma_private->dma_buf_next = dma_private->dma_buf_phys; 203 204 if (++dma_private->current_link >= NUM_DMA_LINKS) 205 dma_private->current_link = 0; 206 } 207 208 /** 209 * fsl_dma_isr: interrupt handler for the DMA controller 210 * 211 * @irq: IRQ of the DMA channel 212 * @dev_id: pointer to the dma_private structure for this DMA channel 213 */ 214 static irqreturn_t fsl_dma_isr(int irq, void *dev_id) 215 { 216 struct fsl_dma_private *dma_private = dev_id; 217 struct snd_pcm_substream *substream = dma_private->substream; 218 struct snd_soc_pcm_runtime *rtd = substream->private_data; 219 struct device *dev = rtd->platform->dev; 220 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel; 221 irqreturn_t ret = IRQ_NONE; 222 u32 sr, sr2 = 0; 223 224 /* We got an interrupt, so read the status register to see what we 225 were interrupted for. 226 */ 227 sr = in_be32(&dma_channel->sr); 228 229 if (sr & CCSR_DMA_SR_TE) { 230 dev_err(dev, "dma transmit error\n"); 231 fsl_dma_abort_stream(substream); 232 sr2 |= CCSR_DMA_SR_TE; 233 ret = IRQ_HANDLED; 234 } 235 236 if (sr & CCSR_DMA_SR_CH) 237 ret = IRQ_HANDLED; 238 239 if (sr & CCSR_DMA_SR_PE) { 240 dev_err(dev, "dma programming error\n"); 241 fsl_dma_abort_stream(substream); 242 sr2 |= CCSR_DMA_SR_PE; 243 ret = IRQ_HANDLED; 244 } 245 246 if (sr & CCSR_DMA_SR_EOLNI) { 247 sr2 |= CCSR_DMA_SR_EOLNI; 248 ret = IRQ_HANDLED; 249 } 250 251 if (sr & CCSR_DMA_SR_CB) 252 ret = IRQ_HANDLED; 253 254 if (sr & CCSR_DMA_SR_EOSI) { 255 /* Tell ALSA we completed a period. */ 256 snd_pcm_period_elapsed(substream); 257 258 /* 259 * Update our link descriptors to point to the next period. We 260 * only need to do this if the number of periods is not equal to 261 * the number of links. 262 */ 263 if (dma_private->num_periods != NUM_DMA_LINKS) 264 fsl_dma_update_pointers(dma_private); 265 266 sr2 |= CCSR_DMA_SR_EOSI; 267 ret = IRQ_HANDLED; 268 } 269 270 if (sr & CCSR_DMA_SR_EOLSI) { 271 sr2 |= CCSR_DMA_SR_EOLSI; 272 ret = IRQ_HANDLED; 273 } 274 275 /* Clear the bits that we set */ 276 if (sr2) 277 out_be32(&dma_channel->sr, sr2); 278 279 return ret; 280 } 281 282 /** 283 * fsl_dma_new: initialize this PCM driver. 284 * 285 * This function is called when the codec driver calls snd_soc_new_pcms(), 286 * once for each .dai_link in the machine driver's snd_soc_card 287 * structure. 288 * 289 * snd_dma_alloc_pages() is just a front-end to dma_alloc_coherent(), which 290 * (currently) always allocates the DMA buffer in lowmem, even if GFP_HIGHMEM 291 * is specified. Therefore, any DMA buffers we allocate will always be in low 292 * memory, but we support for 36-bit physical addresses anyway. 293 * 294 * Regardless of where the memory is actually allocated, since the device can 295 * technically DMA to any 36-bit address, we do need to set the DMA mask to 36. 296 */ 297 static int fsl_dma_new(struct snd_soc_pcm_runtime *rtd) 298 { 299 struct snd_card *card = rtd->card->snd_card; 300 struct snd_pcm *pcm = rtd->pcm; 301 static u64 fsl_dma_dmamask = DMA_BIT_MASK(36); 302 int ret; 303 304 if (!card->dev->dma_mask) 305 card->dev->dma_mask = &fsl_dma_dmamask; 306 307 if (!card->dev->coherent_dma_mask) 308 card->dev->coherent_dma_mask = fsl_dma_dmamask; 309 310 /* Some codecs have separate DAIs for playback and capture, so we 311 * should allocate a DMA buffer only for the streams that are valid. 312 */ 313 314 if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) { 315 ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, card->dev, 316 fsl_dma_hardware.buffer_bytes_max, 317 &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream->dma_buffer); 318 if (ret) { 319 dev_err(card->dev, "can't alloc playback dma buffer\n"); 320 return ret; 321 } 322 } 323 324 if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) { 325 ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, card->dev, 326 fsl_dma_hardware.buffer_bytes_max, 327 &pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream->dma_buffer); 328 if (ret) { 329 dev_err(card->dev, "can't alloc capture dma buffer\n"); 330 snd_dma_free_pages(&pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream->dma_buffer); 331 return ret; 332 } 333 } 334 335 return 0; 336 } 337 338 /** 339 * fsl_dma_open: open a new substream. 340 * 341 * Each substream has its own DMA buffer. 342 * 343 * ALSA divides the DMA buffer into N periods. We create NUM_DMA_LINKS link 344 * descriptors that ping-pong from one period to the next. For example, if 345 * there are six periods and two link descriptors, this is how they look 346 * before playback starts: 347 * 348 * The last link descriptor 349 * ____________ points back to the first 350 * | | 351 * V | 352 * ___ ___ | 353 * | |->| |->| 354 * |___| |___| 355 * | | 356 * | | 357 * V V 358 * _________________________________________ 359 * | | | | | | | The DMA buffer is 360 * | | | | | | | divided into 6 parts 361 * |______|______|______|______|______|______| 362 * 363 * and here's how they look after the first period is finished playing: 364 * 365 * ____________ 366 * | | 367 * V | 368 * ___ ___ | 369 * | |->| |->| 370 * |___| |___| 371 * | | 372 * |______________ 373 * | | 374 * V V 375 * _________________________________________ 376 * | | | | | | | 377 * | | | | | | | 378 * |______|______|______|______|______|______| 379 * 380 * The first link descriptor now points to the third period. The DMA 381 * controller is currently playing the second period. When it finishes, it 382 * will jump back to the first descriptor and play the third period. 383 * 384 * There are four reasons we do this: 385 * 386 * 1. The only way to get the DMA controller to automatically restart the 387 * transfer when it gets to the end of the buffer is to use chaining 388 * mode. Basic direct mode doesn't offer that feature. 389 * 2. We need to receive an interrupt at the end of every period. The DMA 390 * controller can generate an interrupt at the end of every link transfer 391 * (aka segment). Making each period into a DMA segment will give us the 392 * interrupts we need. 393 * 3. By creating only two link descriptors, regardless of the number of 394 * periods, we do not need to reallocate the link descriptors if the 395 * number of periods changes. 396 * 4. All of the audio data is still stored in a single, contiguous DMA 397 * buffer, which is what ALSA expects. We're just dividing it into 398 * contiguous parts, and creating a link descriptor for each one. 399 */ 400 static int fsl_dma_open(struct snd_pcm_substream *substream) 401 { 402 struct snd_pcm_runtime *runtime = substream->runtime; 403 struct snd_soc_pcm_runtime *rtd = substream->private_data; 404 struct device *dev = rtd->platform->dev; 405 struct dma_object *dma = 406 container_of(rtd->platform->driver, struct dma_object, dai); 407 struct fsl_dma_private *dma_private; 408 struct ccsr_dma_channel __iomem *dma_channel; 409 dma_addr_t ld_buf_phys; 410 u64 temp_link; /* Pointer to next link descriptor */ 411 u32 mr; 412 unsigned int channel; 413 int ret = 0; 414 unsigned int i; 415 416 /* 417 * Reject any DMA buffer whose size is not a multiple of the period 418 * size. We need to make sure that the DMA buffer can be evenly divided 419 * into periods. 420 */ 421 ret = snd_pcm_hw_constraint_integer(runtime, 422 SNDRV_PCM_HW_PARAM_PERIODS); 423 if (ret < 0) { 424 dev_err(dev, "invalid buffer size\n"); 425 return ret; 426 } 427 428 channel = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1; 429 430 if (dma->assigned) { 431 dev_err(dev, "dma channel already assigned\n"); 432 return -EBUSY; 433 } 434 435 dma_private = dma_alloc_coherent(dev, sizeof(struct fsl_dma_private), 436 &ld_buf_phys, GFP_KERNEL); 437 if (!dma_private) { 438 dev_err(dev, "can't allocate dma private data\n"); 439 return -ENOMEM; 440 } 441 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) 442 dma_private->ssi_sxx_phys = dma->ssi_stx_phys; 443 else 444 dma_private->ssi_sxx_phys = dma->ssi_srx_phys; 445 446 dma_private->ssi_fifo_depth = dma->ssi_fifo_depth; 447 dma_private->dma_channel = dma->channel; 448 dma_private->irq = dma->irq; 449 dma_private->substream = substream; 450 dma_private->ld_buf_phys = ld_buf_phys; 451 dma_private->dma_buf_phys = substream->dma_buffer.addr; 452 453 ret = request_irq(dma_private->irq, fsl_dma_isr, 0, "fsldma-audio", 454 dma_private); 455 if (ret) { 456 dev_err(dev, "can't register ISR for IRQ %u (ret=%i)\n", 457 dma_private->irq, ret); 458 dma_free_coherent(dev, sizeof(struct fsl_dma_private), 459 dma_private, dma_private->ld_buf_phys); 460 return ret; 461 } 462 463 dma->assigned = 1; 464 465 snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer); 466 snd_soc_set_runtime_hwparams(substream, &fsl_dma_hardware); 467 runtime->private_data = dma_private; 468 469 /* Program the fixed DMA controller parameters */ 470 471 dma_channel = dma_private->dma_channel; 472 473 temp_link = dma_private->ld_buf_phys + 474 sizeof(struct fsl_dma_link_descriptor); 475 476 for (i = 0; i < NUM_DMA_LINKS; i++) { 477 dma_private->link[i].next = cpu_to_be64(temp_link); 478 479 temp_link += sizeof(struct fsl_dma_link_descriptor); 480 } 481 /* The last link descriptor points to the first */ 482 dma_private->link[i - 1].next = cpu_to_be64(dma_private->ld_buf_phys); 483 484 /* Tell the DMA controller where the first link descriptor is */ 485 out_be32(&dma_channel->clndar, 486 CCSR_DMA_CLNDAR_ADDR(dma_private->ld_buf_phys)); 487 out_be32(&dma_channel->eclndar, 488 CCSR_DMA_ECLNDAR_ADDR(dma_private->ld_buf_phys)); 489 490 /* The manual says the BCR must be clear before enabling EMP */ 491 out_be32(&dma_channel->bcr, 0); 492 493 /* 494 * Program the mode register for interrupts, external master control, 495 * and source/destination hold. Also clear the Channel Abort bit. 496 */ 497 mr = in_be32(&dma_channel->mr) & 498 ~(CCSR_DMA_MR_CA | CCSR_DMA_MR_DAHE | CCSR_DMA_MR_SAHE); 499 500 /* 501 * We want External Master Start and External Master Pause enabled, 502 * because the SSI is controlling the DMA controller. We want the DMA 503 * controller to be set up in advance, and then we signal only the SSI 504 * to start transferring. 505 * 506 * We want End-Of-Segment Interrupts enabled, because this will generate 507 * an interrupt at the end of each segment (each link descriptor 508 * represents one segment). Each DMA segment is the same thing as an 509 * ALSA period, so this is how we get an interrupt at the end of every 510 * period. 511 * 512 * We want Error Interrupt enabled, so that we can get an error if 513 * the DMA controller is mis-programmed somehow. 514 */ 515 mr |= CCSR_DMA_MR_EOSIE | CCSR_DMA_MR_EIE | CCSR_DMA_MR_EMP_EN | 516 CCSR_DMA_MR_EMS_EN; 517 518 /* For playback, we want the destination address to be held. For 519 capture, set the source address to be held. */ 520 mr |= (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ? 521 CCSR_DMA_MR_DAHE : CCSR_DMA_MR_SAHE; 522 523 out_be32(&dma_channel->mr, mr); 524 525 return 0; 526 } 527 528 /** 529 * fsl_dma_hw_params: continue initializing the DMA links 530 * 531 * This function obtains hardware parameters about the opened stream and 532 * programs the DMA controller accordingly. 533 * 534 * One drawback of big-endian is that when copying integers of different 535 * sizes to a fixed-sized register, the address to which the integer must be 536 * copied is dependent on the size of the integer. 537 * 538 * For example, if P is the address of a 32-bit register, and X is a 32-bit 539 * integer, then X should be copied to address P. However, if X is a 16-bit 540 * integer, then it should be copied to P+2. If X is an 8-bit register, 541 * then it should be copied to P+3. 542 * 543 * So for playback of 8-bit samples, the DMA controller must transfer single 544 * bytes from the DMA buffer to the last byte of the STX0 register, i.e. 545 * offset by 3 bytes. For 16-bit samples, the offset is two bytes. 546 * 547 * For 24-bit samples, the offset is 1 byte. However, the DMA controller 548 * does not support 3-byte copies (the DAHTS register supports only 1, 2, 4, 549 * and 8 bytes at a time). So we do not support packed 24-bit samples. 550 * 24-bit data must be padded to 32 bits. 551 */ 552 static int fsl_dma_hw_params(struct snd_pcm_substream *substream, 553 struct snd_pcm_hw_params *hw_params) 554 { 555 struct snd_pcm_runtime *runtime = substream->runtime; 556 struct fsl_dma_private *dma_private = runtime->private_data; 557 struct snd_soc_pcm_runtime *rtd = substream->private_data; 558 struct device *dev = rtd->platform->dev; 559 560 /* Number of bits per sample */ 561 unsigned int sample_bits = 562 snd_pcm_format_physical_width(params_format(hw_params)); 563 564 /* Number of bytes per frame */ 565 unsigned int sample_bytes = sample_bits / 8; 566 567 /* Bus address of SSI STX register */ 568 dma_addr_t ssi_sxx_phys = dma_private->ssi_sxx_phys; 569 570 /* Size of the DMA buffer, in bytes */ 571 size_t buffer_size = params_buffer_bytes(hw_params); 572 573 /* Number of bytes per period */ 574 size_t period_size = params_period_bytes(hw_params); 575 576 /* Pointer to next period */ 577 dma_addr_t temp_addr = substream->dma_buffer.addr; 578 579 /* Pointer to DMA controller */ 580 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel; 581 582 u32 mr; /* DMA Mode Register */ 583 584 unsigned int i; 585 586 /* Initialize our DMA tracking variables */ 587 dma_private->period_size = period_size; 588 dma_private->num_periods = params_periods(hw_params); 589 dma_private->dma_buf_end = dma_private->dma_buf_phys + buffer_size; 590 dma_private->dma_buf_next = dma_private->dma_buf_phys + 591 (NUM_DMA_LINKS * period_size); 592 593 if (dma_private->dma_buf_next >= dma_private->dma_buf_end) 594 /* This happens if the number of periods == NUM_DMA_LINKS */ 595 dma_private->dma_buf_next = dma_private->dma_buf_phys; 596 597 mr = in_be32(&dma_channel->mr) & ~(CCSR_DMA_MR_BWC_MASK | 598 CCSR_DMA_MR_SAHTS_MASK | CCSR_DMA_MR_DAHTS_MASK); 599 600 /* Due to a quirk of the SSI's STX register, the target address 601 * for the DMA operations depends on the sample size. So we calculate 602 * that offset here. While we're at it, also tell the DMA controller 603 * how much data to transfer per sample. 604 */ 605 switch (sample_bits) { 606 case 8: 607 mr |= CCSR_DMA_MR_DAHTS_1 | CCSR_DMA_MR_SAHTS_1; 608 ssi_sxx_phys += 3; 609 break; 610 case 16: 611 mr |= CCSR_DMA_MR_DAHTS_2 | CCSR_DMA_MR_SAHTS_2; 612 ssi_sxx_phys += 2; 613 break; 614 case 32: 615 mr |= CCSR_DMA_MR_DAHTS_4 | CCSR_DMA_MR_SAHTS_4; 616 break; 617 default: 618 /* We should never get here */ 619 dev_err(dev, "unsupported sample size %u\n", sample_bits); 620 return -EINVAL; 621 } 622 623 /* 624 * BWC determines how many bytes are sent/received before the DMA 625 * controller checks the SSI to see if it needs to stop. BWC should 626 * always be a multiple of the frame size, so that we always transmit 627 * whole frames. Each frame occupies two slots in the FIFO. The 628 * parameter for CCSR_DMA_MR_BWC() is rounded down the next power of two 629 * (MR[BWC] can only represent even powers of two). 630 * 631 * To simplify the process, we set BWC to the largest value that is 632 * less than or equal to the FIFO watermark. For playback, this ensures 633 * that we transfer the maximum amount without overrunning the FIFO. 634 * For capture, this ensures that we transfer the maximum amount without 635 * underrunning the FIFO. 636 * 637 * f = SSI FIFO depth 638 * w = SSI watermark value (which equals f - 2) 639 * b = DMA bandwidth count (in bytes) 640 * s = sample size (in bytes, which equals frame_size * 2) 641 * 642 * For playback, we never transmit more than the transmit FIFO 643 * watermark, otherwise we might write more data than the FIFO can hold. 644 * The watermark is equal to the FIFO depth minus two. 645 * 646 * For capture, two equations must hold: 647 * w > f - (b / s) 648 * w >= b / s 649 * 650 * So, b > 2 * s, but b must also be <= s * w. To simplify, we set 651 * b = s * w, which is equal to 652 * (dma_private->ssi_fifo_depth - 2) * sample_bytes. 653 */ 654 mr |= CCSR_DMA_MR_BWC((dma_private->ssi_fifo_depth - 2) * sample_bytes); 655 656 out_be32(&dma_channel->mr, mr); 657 658 for (i = 0; i < NUM_DMA_LINKS; i++) { 659 struct fsl_dma_link_descriptor *link = &dma_private->link[i]; 660 661 link->count = cpu_to_be32(period_size); 662 663 /* The snoop bit tells the DMA controller whether it should tell 664 * the ECM to snoop during a read or write to an address. For 665 * audio, we use DMA to transfer data between memory and an I/O 666 * device (the SSI's STX0 or SRX0 register). Snooping is only 667 * needed if there is a cache, so we need to snoop memory 668 * addresses only. For playback, that means we snoop the source 669 * but not the destination. For capture, we snoop the 670 * destination but not the source. 671 * 672 * Note that failing to snoop properly is unlikely to cause 673 * cache incoherency if the period size is larger than the 674 * size of L1 cache. This is because filling in one period will 675 * flush out the data for the previous period. So if you 676 * increased period_bytes_min to a large enough size, you might 677 * get more performance by not snooping, and you'll still be 678 * okay. You'll need to update fsl_dma_update_pointers() also. 679 */ 680 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { 681 link->source_addr = cpu_to_be32(temp_addr); 682 link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP | 683 upper_32_bits(temp_addr)); 684 685 link->dest_addr = cpu_to_be32(ssi_sxx_phys); 686 link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP | 687 upper_32_bits(ssi_sxx_phys)); 688 } else { 689 link->source_addr = cpu_to_be32(ssi_sxx_phys); 690 link->source_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP | 691 upper_32_bits(ssi_sxx_phys)); 692 693 link->dest_addr = cpu_to_be32(temp_addr); 694 link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP | 695 upper_32_bits(temp_addr)); 696 } 697 698 temp_addr += period_size; 699 } 700 701 return 0; 702 } 703 704 /** 705 * fsl_dma_pointer: determine the current position of the DMA transfer 706 * 707 * This function is called by ALSA when ALSA wants to know where in the 708 * stream buffer the hardware currently is. 709 * 710 * For playback, the SAR register contains the physical address of the most 711 * recent DMA transfer. For capture, the value is in the DAR register. 712 * 713 * The base address of the buffer is stored in the source_addr field of the 714 * first link descriptor. 715 */ 716 static snd_pcm_uframes_t fsl_dma_pointer(struct snd_pcm_substream *substream) 717 { 718 struct snd_pcm_runtime *runtime = substream->runtime; 719 struct fsl_dma_private *dma_private = runtime->private_data; 720 struct snd_soc_pcm_runtime *rtd = substream->private_data; 721 struct device *dev = rtd->platform->dev; 722 struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel; 723 dma_addr_t position; 724 snd_pcm_uframes_t frames; 725 726 /* Obtain the current DMA pointer, but don't read the ESAD bits if we 727 * only have 32-bit DMA addresses. This function is typically called 728 * in interrupt context, so we need to optimize it. 729 */ 730 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { 731 position = in_be32(&dma_channel->sar); 732 #ifdef CONFIG_PHYS_64BIT 733 position |= (u64)(in_be32(&dma_channel->satr) & 734 CCSR_DMA_ATR_ESAD_MASK) << 32; 735 #endif 736 } else { 737 position = in_be32(&dma_channel->dar); 738 #ifdef CONFIG_PHYS_64BIT 739 position |= (u64)(in_be32(&dma_channel->datr) & 740 CCSR_DMA_ATR_ESAD_MASK) << 32; 741 #endif 742 } 743 744 /* 745 * When capture is started, the SSI immediately starts to fill its FIFO. 746 * This means that the DMA controller is not started until the FIFO is 747 * full. However, ALSA calls this function before that happens, when 748 * MR.DAR is still zero. In this case, just return zero to indicate 749 * that nothing has been received yet. 750 */ 751 if (!position) 752 return 0; 753 754 if ((position < dma_private->dma_buf_phys) || 755 (position > dma_private->dma_buf_end)) { 756 dev_err(dev, "dma pointer is out of range, halting stream\n"); 757 return SNDRV_PCM_POS_XRUN; 758 } 759 760 frames = bytes_to_frames(runtime, position - dma_private->dma_buf_phys); 761 762 /* 763 * If the current address is just past the end of the buffer, wrap it 764 * around. 765 */ 766 if (frames == runtime->buffer_size) 767 frames = 0; 768 769 return frames; 770 } 771 772 /** 773 * fsl_dma_hw_free: release resources allocated in fsl_dma_hw_params() 774 * 775 * Release the resources allocated in fsl_dma_hw_params() and de-program the 776 * registers. 777 * 778 * This function can be called multiple times. 779 */ 780 static int fsl_dma_hw_free(struct snd_pcm_substream *substream) 781 { 782 struct snd_pcm_runtime *runtime = substream->runtime; 783 struct fsl_dma_private *dma_private = runtime->private_data; 784 785 if (dma_private) { 786 struct ccsr_dma_channel __iomem *dma_channel; 787 788 dma_channel = dma_private->dma_channel; 789 790 /* Stop the DMA */ 791 out_be32(&dma_channel->mr, CCSR_DMA_MR_CA); 792 out_be32(&dma_channel->mr, 0); 793 794 /* Reset all the other registers */ 795 out_be32(&dma_channel->sr, -1); 796 out_be32(&dma_channel->clndar, 0); 797 out_be32(&dma_channel->eclndar, 0); 798 out_be32(&dma_channel->satr, 0); 799 out_be32(&dma_channel->sar, 0); 800 out_be32(&dma_channel->datr, 0); 801 out_be32(&dma_channel->dar, 0); 802 out_be32(&dma_channel->bcr, 0); 803 out_be32(&dma_channel->nlndar, 0); 804 out_be32(&dma_channel->enlndar, 0); 805 } 806 807 return 0; 808 } 809 810 /** 811 * fsl_dma_close: close the stream. 812 */ 813 static int fsl_dma_close(struct snd_pcm_substream *substream) 814 { 815 struct snd_pcm_runtime *runtime = substream->runtime; 816 struct fsl_dma_private *dma_private = runtime->private_data; 817 struct snd_soc_pcm_runtime *rtd = substream->private_data; 818 struct device *dev = rtd->platform->dev; 819 struct dma_object *dma = 820 container_of(rtd->platform->driver, struct dma_object, dai); 821 822 if (dma_private) { 823 if (dma_private->irq) 824 free_irq(dma_private->irq, dma_private); 825 826 /* Deallocate the fsl_dma_private structure */ 827 dma_free_coherent(dev, sizeof(struct fsl_dma_private), 828 dma_private, dma_private->ld_buf_phys); 829 substream->runtime->private_data = NULL; 830 } 831 832 dma->assigned = 0; 833 834 return 0; 835 } 836 837 /* 838 * Remove this PCM driver. 839 */ 840 static void fsl_dma_free_dma_buffers(struct snd_pcm *pcm) 841 { 842 struct snd_pcm_substream *substream; 843 unsigned int i; 844 845 for (i = 0; i < ARRAY_SIZE(pcm->streams); i++) { 846 substream = pcm->streams[i].substream; 847 if (substream) { 848 snd_dma_free_pages(&substream->dma_buffer); 849 substream->dma_buffer.area = NULL; 850 substream->dma_buffer.addr = 0; 851 } 852 } 853 } 854 855 /** 856 * find_ssi_node -- returns the SSI node that points to his DMA channel node 857 * 858 * Although this DMA driver attempts to operate independently of the other 859 * devices, it still needs to determine some information about the SSI device 860 * that it's working with. Unfortunately, the device tree does not contain 861 * a pointer from the DMA channel node to the SSI node -- the pointer goes the 862 * other way. So we need to scan the device tree for SSI nodes until we find 863 * the one that points to the given DMA channel node. It's ugly, but at least 864 * it's contained in this one function. 865 */ 866 static struct device_node *find_ssi_node(struct device_node *dma_channel_np) 867 { 868 struct device_node *ssi_np, *np; 869 870 for_each_compatible_node(ssi_np, NULL, "fsl,mpc8610-ssi") { 871 /* Check each DMA phandle to see if it points to us. We 872 * assume that device_node pointers are a valid comparison. 873 */ 874 np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0); 875 of_node_put(np); 876 if (np == dma_channel_np) 877 return ssi_np; 878 879 np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0); 880 of_node_put(np); 881 if (np == dma_channel_np) 882 return ssi_np; 883 } 884 885 return NULL; 886 } 887 888 static struct snd_pcm_ops fsl_dma_ops = { 889 .open = fsl_dma_open, 890 .close = fsl_dma_close, 891 .ioctl = snd_pcm_lib_ioctl, 892 .hw_params = fsl_dma_hw_params, 893 .hw_free = fsl_dma_hw_free, 894 .pointer = fsl_dma_pointer, 895 }; 896 897 static int fsl_soc_dma_probe(struct platform_device *pdev) 898 { 899 struct dma_object *dma; 900 struct device_node *np = pdev->dev.of_node; 901 struct device_node *ssi_np; 902 struct resource res; 903 const uint32_t *iprop; 904 int ret; 905 906 /* Find the SSI node that points to us. */ 907 ssi_np = find_ssi_node(np); 908 if (!ssi_np) { 909 dev_err(&pdev->dev, "cannot find parent SSI node\n"); 910 return -ENODEV; 911 } 912 913 ret = of_address_to_resource(ssi_np, 0, &res); 914 if (ret) { 915 dev_err(&pdev->dev, "could not determine resources for %s\n", 916 ssi_np->full_name); 917 of_node_put(ssi_np); 918 return ret; 919 } 920 921 dma = kzalloc(sizeof(*dma) + strlen(np->full_name), GFP_KERNEL); 922 if (!dma) { 923 dev_err(&pdev->dev, "could not allocate dma object\n"); 924 of_node_put(ssi_np); 925 return -ENOMEM; 926 } 927 928 strcpy(dma->path, np->full_name); 929 dma->dai.ops = &fsl_dma_ops; 930 dma->dai.pcm_new = fsl_dma_new; 931 dma->dai.pcm_free = fsl_dma_free_dma_buffers; 932 933 /* Store the SSI-specific information that we need */ 934 dma->ssi_stx_phys = res.start + offsetof(struct ccsr_ssi, stx0); 935 dma->ssi_srx_phys = res.start + offsetof(struct ccsr_ssi, srx0); 936 937 iprop = of_get_property(ssi_np, "fsl,fifo-depth", NULL); 938 if (iprop) 939 dma->ssi_fifo_depth = be32_to_cpup(iprop); 940 else 941 /* Older 8610 DTs didn't have the fifo-depth property */ 942 dma->ssi_fifo_depth = 8; 943 944 of_node_put(ssi_np); 945 946 ret = snd_soc_register_platform(&pdev->dev, &dma->dai); 947 if (ret) { 948 dev_err(&pdev->dev, "could not register platform\n"); 949 kfree(dma); 950 return ret; 951 } 952 953 dma->channel = of_iomap(np, 0); 954 dma->irq = irq_of_parse_and_map(np, 0); 955 956 dev_set_drvdata(&pdev->dev, dma); 957 958 return 0; 959 } 960 961 static int fsl_soc_dma_remove(struct platform_device *pdev) 962 { 963 struct dma_object *dma = dev_get_drvdata(&pdev->dev); 964 965 snd_soc_unregister_platform(&pdev->dev); 966 iounmap(dma->channel); 967 irq_dispose_mapping(dma->irq); 968 kfree(dma); 969 970 return 0; 971 } 972 973 static const struct of_device_id fsl_soc_dma_ids[] = { 974 { .compatible = "fsl,ssi-dma-channel", }, 975 {} 976 }; 977 MODULE_DEVICE_TABLE(of, fsl_soc_dma_ids); 978 979 static struct platform_driver fsl_soc_dma_driver = { 980 .driver = { 981 .name = "fsl-pcm-audio", 982 .owner = THIS_MODULE, 983 .of_match_table = fsl_soc_dma_ids, 984 }, 985 .probe = fsl_soc_dma_probe, 986 .remove = fsl_soc_dma_remove, 987 }; 988 989 module_platform_driver(fsl_soc_dma_driver); 990 991 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>"); 992 MODULE_DESCRIPTION("Freescale Elo DMA ASoC PCM Driver"); 993 MODULE_LICENSE("GPL v2"); 994