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 * SPDX-License-Identifier: GPL-2.0+ 11 */ 12 13 #include <linux/list.h> 14 15 #include <common.h> 16 #include <malloc.h> 17 #include <linux/errno.h> 18 #include <asm/io.h> 19 #include <asm/arch/clock.h> 20 #include <asm/arch/imx-regs.h> 21 #include <asm/arch/sys_proto.h> 22 #include <asm/mach-imx/dma.h> 23 #include <asm/mach-imx/regs-apbh.h> 24 25 static struct mxs_dma_chan mxs_dma_channels[MXS_MAX_DMA_CHANNELS]; 26 27 /* 28 * Test is the DMA channel is valid channel 29 */ 30 int mxs_dma_validate_chan(int channel) 31 { 32 struct mxs_dma_chan *pchan; 33 34 if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS)) 35 return -EINVAL; 36 37 pchan = mxs_dma_channels + channel; 38 if (!(pchan->flags & MXS_DMA_FLAGS_ALLOCATED)) 39 return -EINVAL; 40 41 return 0; 42 } 43 44 /* 45 * Return the address of the command within a descriptor. 46 */ 47 static unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc) 48 { 49 return desc->address + offsetof(struct mxs_dma_desc, cmd); 50 } 51 52 /* 53 * Read a DMA channel's hardware semaphore. 54 * 55 * As used by the MXS platform's DMA software, the DMA channel's hardware 56 * semaphore reflects the number of DMA commands the hardware will process, but 57 * has not yet finished. This is a volatile value read directly from hardware, 58 * so it must be be viewed as immediately stale. 59 * 60 * If the channel is not marked busy, or has finished processing all its 61 * commands, this value should be zero. 62 * 63 * See mxs_dma_append() for details on how DMA command blocks must be configured 64 * to maintain the expected behavior of the semaphore's value. 65 */ 66 static int mxs_dma_read_semaphore(int channel) 67 { 68 struct mxs_apbh_regs *apbh_regs = 69 (struct mxs_apbh_regs *)MXS_APBH_BASE; 70 uint32_t tmp; 71 int ret; 72 73 ret = mxs_dma_validate_chan(channel); 74 if (ret) 75 return ret; 76 77 tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema); 78 79 tmp &= APBH_CHn_SEMA_PHORE_MASK; 80 tmp >>= APBH_CHn_SEMA_PHORE_OFFSET; 81 82 return tmp; 83 } 84 85 #ifndef CONFIG_SYS_DCACHE_OFF 86 void mxs_dma_flush_desc(struct mxs_dma_desc *desc) 87 { 88 uint32_t addr; 89 uint32_t size; 90 91 addr = (uint32_t)desc; 92 size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT); 93 94 flush_dcache_range(addr, addr + size); 95 } 96 #else 97 inline void mxs_dma_flush_desc(struct mxs_dma_desc *desc) {} 98 #endif 99 100 /* 101 * Enable a DMA channel. 102 * 103 * If the given channel has any DMA descriptors on its active list, this 104 * function causes the DMA hardware to begin processing them. 105 * 106 * This function marks the DMA channel as "busy," whether or not there are any 107 * descriptors to process. 108 */ 109 static int mxs_dma_enable(int channel) 110 { 111 struct mxs_apbh_regs *apbh_regs = 112 (struct mxs_apbh_regs *)MXS_APBH_BASE; 113 unsigned int sem; 114 struct mxs_dma_chan *pchan; 115 struct mxs_dma_desc *pdesc; 116 int ret; 117 118 ret = mxs_dma_validate_chan(channel); 119 if (ret) 120 return ret; 121 122 pchan = mxs_dma_channels + channel; 123 124 if (pchan->pending_num == 0) { 125 pchan->flags |= MXS_DMA_FLAGS_BUSY; 126 return 0; 127 } 128 129 pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node); 130 if (pdesc == NULL) 131 return -EFAULT; 132 133 if (pchan->flags & MXS_DMA_FLAGS_BUSY) { 134 if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN)) 135 return 0; 136 137 sem = mxs_dma_read_semaphore(channel); 138 if (sem == 0) 139 return 0; 140 141 if (sem == 1) { 142 pdesc = list_entry(pdesc->node.next, 143 struct mxs_dma_desc, node); 144 writel(mxs_dma_cmd_address(pdesc), 145 &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar); 146 } 147 writel(pchan->pending_num, 148 &apbh_regs->ch[channel].hw_apbh_ch_sema); 149 pchan->active_num += pchan->pending_num; 150 pchan->pending_num = 0; 151 } else { 152 pchan->active_num += pchan->pending_num; 153 pchan->pending_num = 0; 154 writel(mxs_dma_cmd_address(pdesc), 155 &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar); 156 writel(pchan->active_num, 157 &apbh_regs->ch[channel].hw_apbh_ch_sema); 158 writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET), 159 &apbh_regs->hw_apbh_ctrl0_clr); 160 } 161 162 pchan->flags |= MXS_DMA_FLAGS_BUSY; 163 return 0; 164 } 165 166 /* 167 * Disable a DMA channel. 168 * 169 * This function shuts down a DMA channel and marks it as "not busy." Any 170 * descriptors on the active list are immediately moved to the head of the 171 * "done" list, whether or not they have actually been processed by the 172 * hardware. The "ready" flags of these descriptors are NOT cleared, so they 173 * still appear to be active. 174 * 175 * This function immediately shuts down a DMA channel's hardware, aborting any 176 * I/O that may be in progress, potentially leaving I/O hardware in an undefined 177 * state. It is unwise to call this function if there is ANY chance the hardware 178 * is still processing a command. 179 */ 180 static int mxs_dma_disable(int channel) 181 { 182 struct mxs_dma_chan *pchan; 183 struct mxs_apbh_regs *apbh_regs = 184 (struct mxs_apbh_regs *)MXS_APBH_BASE; 185 int ret; 186 187 ret = mxs_dma_validate_chan(channel); 188 if (ret) 189 return ret; 190 191 pchan = mxs_dma_channels + channel; 192 193 if (!(pchan->flags & MXS_DMA_FLAGS_BUSY)) 194 return -EINVAL; 195 196 writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET), 197 &apbh_regs->hw_apbh_ctrl0_set); 198 199 pchan->flags &= ~MXS_DMA_FLAGS_BUSY; 200 pchan->active_num = 0; 201 pchan->pending_num = 0; 202 list_splice_init(&pchan->active, &pchan->done); 203 204 return 0; 205 } 206 207 /* 208 * Resets the DMA channel hardware. 209 */ 210 static int mxs_dma_reset(int channel) 211 { 212 struct mxs_apbh_regs *apbh_regs = 213 (struct mxs_apbh_regs *)MXS_APBH_BASE; 214 int ret; 215 #if defined(CONFIG_MX23) 216 uint32_t setreg = (uint32_t)(&apbh_regs->hw_apbh_ctrl0_set); 217 uint32_t offset = APBH_CTRL0_RESET_CHANNEL_OFFSET; 218 #elif (defined(CONFIG_MX28) || defined(CONFIG_MX6) || defined(CONFIG_MX7)) 219 uint32_t setreg = (uint32_t)(&apbh_regs->hw_apbh_channel_ctrl_set); 220 uint32_t offset = APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET; 221 #endif 222 223 ret = mxs_dma_validate_chan(channel); 224 if (ret) 225 return ret; 226 227 writel(1 << (channel + offset), setreg); 228 229 return 0; 230 } 231 232 /* 233 * Enable or disable DMA interrupt. 234 * 235 * This function enables the given DMA channel to interrupt the CPU. 236 */ 237 static int mxs_dma_enable_irq(int channel, int enable) 238 { 239 struct mxs_apbh_regs *apbh_regs = 240 (struct mxs_apbh_regs *)MXS_APBH_BASE; 241 int ret; 242 243 ret = mxs_dma_validate_chan(channel); 244 if (ret) 245 return ret; 246 247 if (enable) 248 writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET), 249 &apbh_regs->hw_apbh_ctrl1_set); 250 else 251 writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET), 252 &apbh_regs->hw_apbh_ctrl1_clr); 253 254 return 0; 255 } 256 257 /* 258 * Clear DMA interrupt. 259 * 260 * The software that is using the DMA channel must register to receive its 261 * interrupts and, when they arrive, must call this function to clear them. 262 */ 263 static int mxs_dma_ack_irq(int channel) 264 { 265 struct mxs_apbh_regs *apbh_regs = 266 (struct mxs_apbh_regs *)MXS_APBH_BASE; 267 int ret; 268 269 ret = mxs_dma_validate_chan(channel); 270 if (ret) 271 return ret; 272 273 writel(1 << channel, &apbh_regs->hw_apbh_ctrl1_clr); 274 writel(1 << channel, &apbh_regs->hw_apbh_ctrl2_clr); 275 276 return 0; 277 } 278 279 /* 280 * Request to reserve a DMA channel 281 */ 282 static int mxs_dma_request(int channel) 283 { 284 struct mxs_dma_chan *pchan; 285 286 if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS)) 287 return -EINVAL; 288 289 pchan = mxs_dma_channels + channel; 290 if ((pchan->flags & MXS_DMA_FLAGS_VALID) != MXS_DMA_FLAGS_VALID) 291 return -ENODEV; 292 293 if (pchan->flags & MXS_DMA_FLAGS_ALLOCATED) 294 return -EBUSY; 295 296 pchan->flags |= MXS_DMA_FLAGS_ALLOCATED; 297 pchan->active_num = 0; 298 pchan->pending_num = 0; 299 300 INIT_LIST_HEAD(&pchan->active); 301 INIT_LIST_HEAD(&pchan->done); 302 303 return 0; 304 } 305 306 /* 307 * Release a DMA channel. 308 * 309 * This function releases a DMA channel from its current owner. 310 * 311 * The channel will NOT be released if it's marked "busy" (see 312 * mxs_dma_enable()). 313 */ 314 int mxs_dma_release(int channel) 315 { 316 struct mxs_dma_chan *pchan; 317 int ret; 318 319 ret = mxs_dma_validate_chan(channel); 320 if (ret) 321 return ret; 322 323 pchan = mxs_dma_channels + channel; 324 325 if (pchan->flags & MXS_DMA_FLAGS_BUSY) 326 return -EBUSY; 327 328 pchan->dev = 0; 329 pchan->active_num = 0; 330 pchan->pending_num = 0; 331 pchan->flags &= ~MXS_DMA_FLAGS_ALLOCATED; 332 333 return 0; 334 } 335 336 /* 337 * Allocate DMA descriptor 338 */ 339 struct mxs_dma_desc *mxs_dma_desc_alloc(void) 340 { 341 struct mxs_dma_desc *pdesc; 342 uint32_t size; 343 344 size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT); 345 pdesc = memalign(MXS_DMA_ALIGNMENT, size); 346 347 if (pdesc == NULL) 348 return NULL; 349 350 memset(pdesc, 0, sizeof(*pdesc)); 351 pdesc->address = (dma_addr_t)pdesc; 352 353 return pdesc; 354 }; 355 356 /* 357 * Free DMA descriptor 358 */ 359 void mxs_dma_desc_free(struct mxs_dma_desc *pdesc) 360 { 361 if (pdesc == NULL) 362 return; 363 364 free(pdesc); 365 } 366 367 /* 368 * Add a DMA descriptor to a channel. 369 * 370 * If the descriptor list for this channel is not empty, this function sets the 371 * CHAIN bit and the NEXTCMD_ADDR fields in the last descriptor's DMA command so 372 * it will chain to the new descriptor's command. 373 * 374 * Then, this function marks the new descriptor as "ready," adds it to the end 375 * of the active descriptor list, and increments the count of pending 376 * descriptors. 377 * 378 * The MXS platform DMA software imposes some rules on DMA commands to maintain 379 * important invariants. These rules are NOT checked, but they must be carefully 380 * applied by software that uses MXS DMA channels. 381 * 382 * Invariant: 383 * The DMA channel's hardware semaphore must reflect the number of DMA 384 * commands the hardware will process, but has not yet finished. 385 * 386 * Explanation: 387 * A DMA channel begins processing commands when its hardware semaphore is 388 * written with a value greater than zero, and it stops processing commands 389 * when the semaphore returns to zero. 390 * 391 * When a channel finishes a DMA command, it will decrement its semaphore if 392 * the DECREMENT_SEMAPHORE bit is set in that command's flags bits. 393 * 394 * In principle, it's not necessary for the DECREMENT_SEMAPHORE to be set, 395 * unless it suits the purposes of the software. For example, one could 396 * construct a series of five DMA commands, with the DECREMENT_SEMAPHORE 397 * bit set only in the last one. Then, setting the DMA channel's hardware 398 * semaphore to one would cause the entire series of five commands to be 399 * processed. However, this example would violate the invariant given above. 400 * 401 * Rule: 402 * ALL DMA commands MUST have the DECREMENT_SEMAPHORE bit set so that the DMA 403 * channel's hardware semaphore will be decremented EVERY time a command is 404 * processed. 405 */ 406 int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc) 407 { 408 struct mxs_dma_chan *pchan; 409 struct mxs_dma_desc *last; 410 int ret; 411 412 ret = mxs_dma_validate_chan(channel); 413 if (ret) 414 return ret; 415 416 pchan = mxs_dma_channels + channel; 417 418 pdesc->cmd.next = mxs_dma_cmd_address(pdesc); 419 pdesc->flags |= MXS_DMA_DESC_FIRST | MXS_DMA_DESC_LAST; 420 421 if (!list_empty(&pchan->active)) { 422 last = list_entry(pchan->active.prev, struct mxs_dma_desc, 423 node); 424 425 pdesc->flags &= ~MXS_DMA_DESC_FIRST; 426 last->flags &= ~MXS_DMA_DESC_LAST; 427 428 last->cmd.next = mxs_dma_cmd_address(pdesc); 429 last->cmd.data |= MXS_DMA_DESC_CHAIN; 430 431 mxs_dma_flush_desc(last); 432 } 433 pdesc->flags |= MXS_DMA_DESC_READY; 434 if (pdesc->flags & MXS_DMA_DESC_FIRST) 435 pchan->pending_num++; 436 list_add_tail(&pdesc->node, &pchan->active); 437 438 mxs_dma_flush_desc(pdesc); 439 440 return ret; 441 } 442 443 /* 444 * Clean up processed DMA descriptors. 445 * 446 * This function removes processed DMA descriptors from the "active" list. Pass 447 * in a non-NULL list head to get the descriptors moved to your list. Pass NULL 448 * to get the descriptors moved to the channel's "done" list. Descriptors on 449 * the "done" list can be retrieved with mxs_dma_get_finished(). 450 * 451 * This function marks the DMA channel as "not busy" if no unprocessed 452 * descriptors remain on the "active" list. 453 */ 454 static int mxs_dma_finish(int channel, struct list_head *head) 455 { 456 int sem; 457 struct mxs_dma_chan *pchan; 458 struct list_head *p, *q; 459 struct mxs_dma_desc *pdesc; 460 int ret; 461 462 ret = mxs_dma_validate_chan(channel); 463 if (ret) 464 return ret; 465 466 pchan = mxs_dma_channels + channel; 467 468 sem = mxs_dma_read_semaphore(channel); 469 if (sem < 0) 470 return sem; 471 472 if (sem == pchan->active_num) 473 return 0; 474 475 list_for_each_safe(p, q, &pchan->active) { 476 if ((pchan->active_num) <= sem) 477 break; 478 479 pdesc = list_entry(p, struct mxs_dma_desc, node); 480 pdesc->flags &= ~MXS_DMA_DESC_READY; 481 482 if (head) 483 list_move_tail(p, head); 484 else 485 list_move_tail(p, &pchan->done); 486 487 if (pdesc->flags & MXS_DMA_DESC_LAST) 488 pchan->active_num--; 489 } 490 491 if (sem == 0) 492 pchan->flags &= ~MXS_DMA_FLAGS_BUSY; 493 494 return 0; 495 } 496 497 /* 498 * Wait for DMA channel to complete 499 */ 500 static int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan) 501 { 502 struct mxs_apbh_regs *apbh_regs = 503 (struct mxs_apbh_regs *)MXS_APBH_BASE; 504 int ret; 505 506 ret = mxs_dma_validate_chan(chan); 507 if (ret) 508 return ret; 509 510 if (mxs_wait_mask_set(&apbh_regs->hw_apbh_ctrl1_reg, 511 1 << chan, timeout)) { 512 ret = -ETIMEDOUT; 513 mxs_dma_reset(chan); 514 } 515 516 return ret; 517 } 518 519 /* 520 * Execute the DMA channel 521 */ 522 int mxs_dma_go(int chan) 523 { 524 uint32_t timeout = 10000000; 525 int ret; 526 527 LIST_HEAD(tmp_desc_list); 528 529 mxs_dma_enable_irq(chan, 1); 530 mxs_dma_enable(chan); 531 532 /* Wait for DMA to finish. */ 533 ret = mxs_dma_wait_complete(timeout, chan); 534 535 /* Clear out the descriptors we just ran. */ 536 mxs_dma_finish(chan, &tmp_desc_list); 537 538 /* Shut the DMA channel down. */ 539 mxs_dma_ack_irq(chan); 540 mxs_dma_reset(chan); 541 mxs_dma_enable_irq(chan, 0); 542 mxs_dma_disable(chan); 543 544 return ret; 545 } 546 547 /* 548 * Execute a continuously running circular DMA descriptor. 549 * NOTE: This is not intended for general use, but rather 550 * for the LCD driver in Smart-LCD mode. It allows 551 * continuous triggering of the RUN bit there. 552 */ 553 void mxs_dma_circ_start(int chan, struct mxs_dma_desc *pdesc) 554 { 555 struct mxs_apbh_regs *apbh_regs = 556 (struct mxs_apbh_regs *)MXS_APBH_BASE; 557 558 mxs_dma_flush_desc(pdesc); 559 560 mxs_dma_enable_irq(chan, 1); 561 562 writel(mxs_dma_cmd_address(pdesc), 563 &apbh_regs->ch[chan].hw_apbh_ch_nxtcmdar); 564 writel(1, &apbh_regs->ch[chan].hw_apbh_ch_sema); 565 writel(1 << (chan + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET), 566 &apbh_regs->hw_apbh_ctrl0_clr); 567 } 568 569 /* 570 * Initialize the DMA hardware 571 */ 572 void mxs_dma_init(void) 573 { 574 struct mxs_apbh_regs *apbh_regs = 575 (struct mxs_apbh_regs *)MXS_APBH_BASE; 576 577 mxs_reset_block(&apbh_regs->hw_apbh_ctrl0_reg); 578 579 #ifdef CONFIG_APBH_DMA_BURST8 580 writel(APBH_CTRL0_AHB_BURST8_EN, 581 &apbh_regs->hw_apbh_ctrl0_set); 582 #else 583 writel(APBH_CTRL0_AHB_BURST8_EN, 584 &apbh_regs->hw_apbh_ctrl0_clr); 585 #endif 586 587 #ifdef CONFIG_APBH_DMA_BURST 588 writel(APBH_CTRL0_APB_BURST_EN, 589 &apbh_regs->hw_apbh_ctrl0_set); 590 #else 591 writel(APBH_CTRL0_APB_BURST_EN, 592 &apbh_regs->hw_apbh_ctrl0_clr); 593 #endif 594 } 595 596 int mxs_dma_init_channel(int channel) 597 { 598 struct mxs_dma_chan *pchan; 599 int ret; 600 601 pchan = mxs_dma_channels + channel; 602 pchan->flags = MXS_DMA_FLAGS_VALID; 603 604 ret = mxs_dma_request(channel); 605 606 if (ret) { 607 printf("MXS DMA: Can't acquire DMA channel %i\n", 608 channel); 609 return ret; 610 } 611 612 mxs_dma_reset(channel); 613 mxs_dma_ack_irq(channel); 614 615 return 0; 616 } 617