1 /* 2 * Freescale i.MX28 APBH DMA driver 3 * 4 * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com> 5 * on behalf of DENX Software Engineering GmbH 6 * 7 * Based on code from LTIB: 8 * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License as published by 12 * the Free Software Foundation; either version 2 of the License, or 13 * (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License along 21 * with this program; if not, write to the Free Software Foundation, Inc., 22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 23 */ 24 25 #include <linux/list.h> 26 27 #include <common.h> 28 #include <malloc.h> 29 #include <asm/errno.h> 30 #include <asm/io.h> 31 #include <asm/arch/clock.h> 32 #include <asm/arch/imx-regs.h> 33 #include <asm/arch/sys_proto.h> 34 #include <asm/arch/dma.h> 35 36 static struct mxs_dma_chan mxs_dma_channels[MXS_MAX_DMA_CHANNELS]; 37 38 /* 39 * Test is the DMA channel is valid channel 40 */ 41 int mxs_dma_validate_chan(int channel) 42 { 43 struct mxs_dma_chan *pchan; 44 45 if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS)) 46 return -EINVAL; 47 48 pchan = mxs_dma_channels + channel; 49 if (!(pchan->flags & MXS_DMA_FLAGS_ALLOCATED)) 50 return -EINVAL; 51 52 return 0; 53 } 54 55 /* 56 * Return the address of the command within a descriptor. 57 */ 58 static unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc) 59 { 60 return desc->address + offsetof(struct mxs_dma_desc, cmd); 61 } 62 63 /* 64 * Read a DMA channel's hardware semaphore. 65 * 66 * As used by the MXS platform's DMA software, the DMA channel's hardware 67 * semaphore reflects the number of DMA commands the hardware will process, but 68 * has not yet finished. This is a volatile value read directly from hardware, 69 * so it must be be viewed as immediately stale. 70 * 71 * If the channel is not marked busy, or has finished processing all its 72 * commands, this value should be zero. 73 * 74 * See mxs_dma_append() for details on how DMA command blocks must be configured 75 * to maintain the expected behavior of the semaphore's value. 76 */ 77 static int mxs_dma_read_semaphore(int channel) 78 { 79 struct mx28_apbh_regs *apbh_regs = 80 (struct mx28_apbh_regs *)MXS_APBH_BASE; 81 uint32_t tmp; 82 int ret; 83 84 ret = mxs_dma_validate_chan(channel); 85 if (ret) 86 return ret; 87 88 tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema); 89 90 tmp &= APBH_CHn_SEMA_PHORE_MASK; 91 tmp >>= APBH_CHn_SEMA_PHORE_OFFSET; 92 93 return tmp; 94 } 95 96 #ifndef CONFIG_SYS_DCACHE_OFF 97 void mxs_dma_flush_desc(struct mxs_dma_desc *desc) 98 { 99 uint32_t addr; 100 uint32_t size; 101 102 addr = (uint32_t)desc; 103 size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT); 104 105 flush_dcache_range(addr, addr + size); 106 } 107 #else 108 inline void mxs_dma_flush_desc(struct mxs_dma_desc *desc) {} 109 #endif 110 111 /* 112 * Enable a DMA channel. 113 * 114 * If the given channel has any DMA descriptors on its active list, this 115 * function causes the DMA hardware to begin processing them. 116 * 117 * This function marks the DMA channel as "busy," whether or not there are any 118 * descriptors to process. 119 */ 120 static int mxs_dma_enable(int channel) 121 { 122 struct mx28_apbh_regs *apbh_regs = 123 (struct mx28_apbh_regs *)MXS_APBH_BASE; 124 unsigned int sem; 125 struct mxs_dma_chan *pchan; 126 struct mxs_dma_desc *pdesc; 127 int ret; 128 129 ret = mxs_dma_validate_chan(channel); 130 if (ret) 131 return ret; 132 133 pchan = mxs_dma_channels + channel; 134 135 if (pchan->pending_num == 0) { 136 pchan->flags |= MXS_DMA_FLAGS_BUSY; 137 return 0; 138 } 139 140 pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node); 141 if (pdesc == NULL) 142 return -EFAULT; 143 144 if (pchan->flags & MXS_DMA_FLAGS_BUSY) { 145 if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN)) 146 return 0; 147 148 sem = mxs_dma_read_semaphore(channel); 149 if (sem == 0) 150 return 0; 151 152 if (sem == 1) { 153 pdesc = list_entry(pdesc->node.next, 154 struct mxs_dma_desc, node); 155 writel(mxs_dma_cmd_address(pdesc), 156 &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar); 157 } 158 writel(pchan->pending_num, 159 &apbh_regs->ch[channel].hw_apbh_ch_sema); 160 pchan->active_num += pchan->pending_num; 161 pchan->pending_num = 0; 162 } else { 163 pchan->active_num += pchan->pending_num; 164 pchan->pending_num = 0; 165 writel(mxs_dma_cmd_address(pdesc), 166 &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar); 167 writel(pchan->active_num, 168 &apbh_regs->ch[channel].hw_apbh_ch_sema); 169 writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET), 170 &apbh_regs->hw_apbh_ctrl0_clr); 171 } 172 173 pchan->flags |= MXS_DMA_FLAGS_BUSY; 174 return 0; 175 } 176 177 /* 178 * Disable a DMA channel. 179 * 180 * This function shuts down a DMA channel and marks it as "not busy." Any 181 * descriptors on the active list are immediately moved to the head of the 182 * "done" list, whether or not they have actually been processed by the 183 * hardware. The "ready" flags of these descriptors are NOT cleared, so they 184 * still appear to be active. 185 * 186 * This function immediately shuts down a DMA channel's hardware, aborting any 187 * I/O that may be in progress, potentially leaving I/O hardware in an undefined 188 * state. It is unwise to call this function if there is ANY chance the hardware 189 * is still processing a command. 190 */ 191 static int mxs_dma_disable(int channel) 192 { 193 struct mxs_dma_chan *pchan; 194 struct mx28_apbh_regs *apbh_regs = 195 (struct mx28_apbh_regs *)MXS_APBH_BASE; 196 int ret; 197 198 ret = mxs_dma_validate_chan(channel); 199 if (ret) 200 return ret; 201 202 pchan = mxs_dma_channels + channel; 203 204 if (!(pchan->flags & MXS_DMA_FLAGS_BUSY)) 205 return -EINVAL; 206 207 writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET), 208 &apbh_regs->hw_apbh_ctrl0_set); 209 210 pchan->flags &= ~MXS_DMA_FLAGS_BUSY; 211 pchan->active_num = 0; 212 pchan->pending_num = 0; 213 list_splice_init(&pchan->active, &pchan->done); 214 215 return 0; 216 } 217 218 /* 219 * Resets the DMA channel hardware. 220 */ 221 static int mxs_dma_reset(int channel) 222 { 223 struct mx28_apbh_regs *apbh_regs = 224 (struct mx28_apbh_regs *)MXS_APBH_BASE; 225 int ret; 226 227 ret = mxs_dma_validate_chan(channel); 228 if (ret) 229 return ret; 230 231 writel(1 << (channel + APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET), 232 &apbh_regs->hw_apbh_channel_ctrl_set); 233 234 return 0; 235 } 236 237 /* 238 * Enable or disable DMA interrupt. 239 * 240 * This function enables the given DMA channel to interrupt the CPU. 241 */ 242 static int mxs_dma_enable_irq(int channel, int enable) 243 { 244 struct mx28_apbh_regs *apbh_regs = 245 (struct mx28_apbh_regs *)MXS_APBH_BASE; 246 int ret; 247 248 ret = mxs_dma_validate_chan(channel); 249 if (ret) 250 return ret; 251 252 if (enable) 253 writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET), 254 &apbh_regs->hw_apbh_ctrl1_set); 255 else 256 writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET), 257 &apbh_regs->hw_apbh_ctrl1_clr); 258 259 return 0; 260 } 261 262 /* 263 * Clear DMA interrupt. 264 * 265 * The software that is using the DMA channel must register to receive its 266 * interrupts and, when they arrive, must call this function to clear them. 267 */ 268 static int mxs_dma_ack_irq(int channel) 269 { 270 struct mx28_apbh_regs *apbh_regs = 271 (struct mx28_apbh_regs *)MXS_APBH_BASE; 272 int ret; 273 274 ret = mxs_dma_validate_chan(channel); 275 if (ret) 276 return ret; 277 278 writel(1 << channel, &apbh_regs->hw_apbh_ctrl1_clr); 279 writel(1 << channel, &apbh_regs->hw_apbh_ctrl2_clr); 280 281 return 0; 282 } 283 284 /* 285 * Request to reserve a DMA channel 286 */ 287 static int mxs_dma_request(int channel) 288 { 289 struct mxs_dma_chan *pchan; 290 291 if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS)) 292 return -EINVAL; 293 294 pchan = mxs_dma_channels + channel; 295 if ((pchan->flags & MXS_DMA_FLAGS_VALID) != MXS_DMA_FLAGS_VALID) 296 return -ENODEV; 297 298 if (pchan->flags & MXS_DMA_FLAGS_ALLOCATED) 299 return -EBUSY; 300 301 pchan->flags |= MXS_DMA_FLAGS_ALLOCATED; 302 pchan->active_num = 0; 303 pchan->pending_num = 0; 304 305 INIT_LIST_HEAD(&pchan->active); 306 INIT_LIST_HEAD(&pchan->done); 307 308 return 0; 309 } 310 311 /* 312 * Release a DMA channel. 313 * 314 * This function releases a DMA channel from its current owner. 315 * 316 * The channel will NOT be released if it's marked "busy" (see 317 * mxs_dma_enable()). 318 */ 319 int mxs_dma_release(int channel) 320 { 321 struct mxs_dma_chan *pchan; 322 int ret; 323 324 ret = mxs_dma_validate_chan(channel); 325 if (ret) 326 return ret; 327 328 pchan = mxs_dma_channels + channel; 329 330 if (pchan->flags & MXS_DMA_FLAGS_BUSY) 331 return -EBUSY; 332 333 pchan->dev = 0; 334 pchan->active_num = 0; 335 pchan->pending_num = 0; 336 pchan->flags &= ~MXS_DMA_FLAGS_ALLOCATED; 337 338 return 0; 339 } 340 341 /* 342 * Allocate DMA descriptor 343 */ 344 struct mxs_dma_desc *mxs_dma_desc_alloc(void) 345 { 346 struct mxs_dma_desc *pdesc; 347 uint32_t size; 348 349 size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT); 350 pdesc = memalign(MXS_DMA_ALIGNMENT, size); 351 352 if (pdesc == NULL) 353 return NULL; 354 355 memset(pdesc, 0, sizeof(*pdesc)); 356 pdesc->address = (dma_addr_t)pdesc; 357 358 return pdesc; 359 }; 360 361 /* 362 * Free DMA descriptor 363 */ 364 void mxs_dma_desc_free(struct mxs_dma_desc *pdesc) 365 { 366 if (pdesc == NULL) 367 return; 368 369 free(pdesc); 370 } 371 372 /* 373 * Add a DMA descriptor to a channel. 374 * 375 * If the descriptor list for this channel is not empty, this function sets the 376 * CHAIN bit and the NEXTCMD_ADDR fields in the last descriptor's DMA command so 377 * it will chain to the new descriptor's command. 378 * 379 * Then, this function marks the new descriptor as "ready," adds it to the end 380 * of the active descriptor list, and increments the count of pending 381 * descriptors. 382 * 383 * The MXS platform DMA software imposes some rules on DMA commands to maintain 384 * important invariants. These rules are NOT checked, but they must be carefully 385 * applied by software that uses MXS DMA channels. 386 * 387 * Invariant: 388 * The DMA channel's hardware semaphore must reflect the number of DMA 389 * commands the hardware will process, but has not yet finished. 390 * 391 * Explanation: 392 * A DMA channel begins processing commands when its hardware semaphore is 393 * written with a value greater than zero, and it stops processing commands 394 * when the semaphore returns to zero. 395 * 396 * When a channel finishes a DMA command, it will decrement its semaphore if 397 * the DECREMENT_SEMAPHORE bit is set in that command's flags bits. 398 * 399 * In principle, it's not necessary for the DECREMENT_SEMAPHORE to be set, 400 * unless it suits the purposes of the software. For example, one could 401 * construct a series of five DMA commands, with the DECREMENT_SEMAPHORE 402 * bit set only in the last one. Then, setting the DMA channel's hardware 403 * semaphore to one would cause the entire series of five commands to be 404 * processed. However, this example would violate the invariant given above. 405 * 406 * Rule: 407 * ALL DMA commands MUST have the DECREMENT_SEMAPHORE bit set so that the DMA 408 * channel's hardware semaphore will be decremented EVERY time a command is 409 * processed. 410 */ 411 int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc) 412 { 413 struct mxs_dma_chan *pchan; 414 struct mxs_dma_desc *last; 415 int ret; 416 417 ret = mxs_dma_validate_chan(channel); 418 if (ret) 419 return ret; 420 421 pchan = mxs_dma_channels + channel; 422 423 pdesc->cmd.next = mxs_dma_cmd_address(pdesc); 424 pdesc->flags |= MXS_DMA_DESC_FIRST | MXS_DMA_DESC_LAST; 425 426 if (!list_empty(&pchan->active)) { 427 last = list_entry(pchan->active.prev, struct mxs_dma_desc, 428 node); 429 430 pdesc->flags &= ~MXS_DMA_DESC_FIRST; 431 last->flags &= ~MXS_DMA_DESC_LAST; 432 433 last->cmd.next = mxs_dma_cmd_address(pdesc); 434 last->cmd.data |= MXS_DMA_DESC_CHAIN; 435 436 mxs_dma_flush_desc(last); 437 } 438 pdesc->flags |= MXS_DMA_DESC_READY; 439 if (pdesc->flags & MXS_DMA_DESC_FIRST) 440 pchan->pending_num++; 441 list_add_tail(&pdesc->node, &pchan->active); 442 443 mxs_dma_flush_desc(pdesc); 444 445 return ret; 446 } 447 448 /* 449 * Clean up processed DMA descriptors. 450 * 451 * This function removes processed DMA descriptors from the "active" list. Pass 452 * in a non-NULL list head to get the descriptors moved to your list. Pass NULL 453 * to get the descriptors moved to the channel's "done" list. Descriptors on 454 * the "done" list can be retrieved with mxs_dma_get_finished(). 455 * 456 * This function marks the DMA channel as "not busy" if no unprocessed 457 * descriptors remain on the "active" list. 458 */ 459 static int mxs_dma_finish(int channel, struct list_head *head) 460 { 461 int sem; 462 struct mxs_dma_chan *pchan; 463 struct list_head *p, *q; 464 struct mxs_dma_desc *pdesc; 465 int ret; 466 467 ret = mxs_dma_validate_chan(channel); 468 if (ret) 469 return ret; 470 471 pchan = mxs_dma_channels + channel; 472 473 sem = mxs_dma_read_semaphore(channel); 474 if (sem < 0) 475 return sem; 476 477 if (sem == pchan->active_num) 478 return 0; 479 480 list_for_each_safe(p, q, &pchan->active) { 481 if ((pchan->active_num) <= sem) 482 break; 483 484 pdesc = list_entry(p, struct mxs_dma_desc, node); 485 pdesc->flags &= ~MXS_DMA_DESC_READY; 486 487 if (head) 488 list_move_tail(p, head); 489 else 490 list_move_tail(p, &pchan->done); 491 492 if (pdesc->flags & MXS_DMA_DESC_LAST) 493 pchan->active_num--; 494 } 495 496 if (sem == 0) 497 pchan->flags &= ~MXS_DMA_FLAGS_BUSY; 498 499 return 0; 500 } 501 502 /* 503 * Wait for DMA channel to complete 504 */ 505 static int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan) 506 { 507 struct mx28_apbh_regs *apbh_regs = 508 (struct mx28_apbh_regs *)MXS_APBH_BASE; 509 int ret; 510 511 ret = mxs_dma_validate_chan(chan); 512 if (ret) 513 return ret; 514 515 if (mx28_wait_mask_set(&apbh_regs->hw_apbh_ctrl1_reg, 516 1 << chan, timeout)) { 517 ret = -ETIMEDOUT; 518 mxs_dma_reset(chan); 519 } 520 521 return ret; 522 } 523 524 /* 525 * Execute the DMA channel 526 */ 527 int mxs_dma_go(int chan) 528 { 529 uint32_t timeout = 10000; 530 int ret; 531 532 LIST_HEAD(tmp_desc_list); 533 534 mxs_dma_enable_irq(chan, 1); 535 mxs_dma_enable(chan); 536 537 /* Wait for DMA to finish. */ 538 ret = mxs_dma_wait_complete(timeout, chan); 539 540 /* Clear out the descriptors we just ran. */ 541 mxs_dma_finish(chan, &tmp_desc_list); 542 543 /* Shut the DMA channel down. */ 544 mxs_dma_ack_irq(chan); 545 mxs_dma_reset(chan); 546 mxs_dma_enable_irq(chan, 0); 547 mxs_dma_disable(chan); 548 549 return ret; 550 } 551 552 /* 553 * Initialize the DMA hardware 554 */ 555 void mxs_dma_init(void) 556 { 557 struct mx28_apbh_regs *apbh_regs = 558 (struct mx28_apbh_regs *)MXS_APBH_BASE; 559 560 mx28_reset_block(&apbh_regs->hw_apbh_ctrl0_reg); 561 562 #ifdef CONFIG_APBH_DMA_BURST8 563 writel(APBH_CTRL0_AHB_BURST8_EN, 564 &apbh_regs->hw_apbh_ctrl0_set); 565 #else 566 writel(APBH_CTRL0_AHB_BURST8_EN, 567 &apbh_regs->hw_apbh_ctrl0_clr); 568 #endif 569 570 #ifdef CONFIG_APBH_DMA_BURST 571 writel(APBH_CTRL0_APB_BURST_EN, 572 &apbh_regs->hw_apbh_ctrl0_set); 573 #else 574 writel(APBH_CTRL0_APB_BURST_EN, 575 &apbh_regs->hw_apbh_ctrl0_clr); 576 #endif 577 } 578 579 int mxs_dma_init_channel(int channel) 580 { 581 struct mxs_dma_chan *pchan; 582 int ret; 583 584 pchan = mxs_dma_channels + channel; 585 pchan->flags = MXS_DMA_FLAGS_VALID; 586 587 ret = mxs_dma_request(channel); 588 589 if (ret) { 590 printf("MXS DMA: Can't acquire DMA channel %i\n", 591 channel); 592 return ret; 593 } 594 595 mxs_dma_reset(channel); 596 mxs_dma_ack_irq(channel); 597 598 return 0; 599 } 600