root/drivers/usb/musb/cppi_dma.c

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DEFINITIONS

This source file includes following definitions.
  1. cpu_drain_writebuffer
  2. cppi_bd_alloc
  3. cppi_bd_free
  4. cppi_reset_rx
  5. cppi_reset_tx
  6. cppi_pool_init
  7. cppi_pool_free
  8. cppi_controller_start
  9. cppi_controller_stop
  10. core_rxirq_disable
  11. core_rxirq_enable
  12. cppi_channel_allocate
  13. cppi_channel_release
  14. cppi_dump_rx
  15. cppi_dump_tx
  16. cppi_rndis_update
  17. cppi_dump_rxbd
  18. cppi_dump_rxq
  19. cppi_autoreq_update
  20. cppi_next_tx_segment
  21. cppi_next_rx_segment
  22. cppi_channel_program
  23. cppi_rx_scan
  24. cppi_interrupt
  25. cppi_dma_controller_create
  26. cppi_dma_controller_destroy
  27. cppi_channel_abort

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2005-2006 by Texas Instruments
   4  *
   5  * This file implements a DMA  interface using TI's CPPI DMA.
   6  * For now it's DaVinci-only, but CPPI isn't specific to DaVinci or USB.
   7  * The TUSB6020, using VLYNQ, has CPPI that looks much like DaVinci.
   8  */
   9 
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/slab.h>
  13 #include <linux/usb.h>
  14 
  15 #include "musb_core.h"
  16 #include "musb_debug.h"
  17 #include "cppi_dma.h"
  18 #include "davinci.h"
  19 
  20 
  21 /* CPPI DMA status 7-mar-2006:
  22  *
  23  * - See musb_{host,gadget}.c for more info
  24  *
  25  * - Correct RX DMA generally forces the engine into irq-per-packet mode,
  26  *   which can easily saturate the CPU under non-mass-storage loads.
  27  *
  28  * NOTES 24-aug-2006 (2.6.18-rc4):
  29  *
  30  * - peripheral RXDMA wedged in a test with packets of length 512/512/1.
  31  *   evidently after the 1 byte packet was received and acked, the queue
  32  *   of BDs got garbaged so it wouldn't empty the fifo.  (rxcsr 0x2003,
  33  *   and RX DMA0: 4 left, 80000000 8feff880, 8feff860 8feff860; 8f321401
  34  *   004001ff 00000001 .. 8feff860)  Host was just getting NAKed on tx
  35  *   of its next (512 byte) packet.  IRQ issues?
  36  *
  37  * REVISIT:  the "transfer DMA" glue between CPPI and USB fifos will
  38  * evidently also directly update the RX and TX CSRs ... so audit all
  39  * host and peripheral side DMA code to avoid CSR access after DMA has
  40  * been started.
  41  */
  42 
  43 /* REVISIT now we can avoid preallocating these descriptors; or
  44  * more simply, switch to a global freelist not per-channel ones.
  45  * Note: at full speed, 64 descriptors == 4K bulk data.
  46  */
  47 #define NUM_TXCHAN_BD       64
  48 #define NUM_RXCHAN_BD       64
  49 
  50 static inline void cpu_drain_writebuffer(void)
  51 {
  52         wmb();
  53 #ifdef  CONFIG_CPU_ARM926T
  54         /* REVISIT this "should not be needed",
  55          * but lack of it sure seemed to hurt ...
  56          */
  57         asm("mcr p15, 0, r0, c7, c10, 4 @ drain write buffer\n");
  58 #endif
  59 }
  60 
  61 static inline struct cppi_descriptor *cppi_bd_alloc(struct cppi_channel *c)
  62 {
  63         struct cppi_descriptor  *bd = c->freelist;
  64 
  65         if (bd)
  66                 c->freelist = bd->next;
  67         return bd;
  68 }
  69 
  70 static inline void
  71 cppi_bd_free(struct cppi_channel *c, struct cppi_descriptor *bd)
  72 {
  73         if (!bd)
  74                 return;
  75         bd->next = c->freelist;
  76         c->freelist = bd;
  77 }
  78 
  79 /*
  80  *  Start DMA controller
  81  *
  82  *  Initialize the DMA controller as necessary.
  83  */
  84 
  85 /* zero out entire rx state RAM entry for the channel */
  86 static void cppi_reset_rx(struct cppi_rx_stateram __iomem *rx)
  87 {
  88         musb_writel(&rx->rx_skipbytes, 0, 0);
  89         musb_writel(&rx->rx_head, 0, 0);
  90         musb_writel(&rx->rx_sop, 0, 0);
  91         musb_writel(&rx->rx_current, 0, 0);
  92         musb_writel(&rx->rx_buf_current, 0, 0);
  93         musb_writel(&rx->rx_len_len, 0, 0);
  94         musb_writel(&rx->rx_cnt_cnt, 0, 0);
  95 }
  96 
  97 /* zero out entire tx state RAM entry for the channel */
  98 static void cppi_reset_tx(struct cppi_tx_stateram __iomem *tx, u32 ptr)
  99 {
 100         musb_writel(&tx->tx_head, 0, 0);
 101         musb_writel(&tx->tx_buf, 0, 0);
 102         musb_writel(&tx->tx_current, 0, 0);
 103         musb_writel(&tx->tx_buf_current, 0, 0);
 104         musb_writel(&tx->tx_info, 0, 0);
 105         musb_writel(&tx->tx_rem_len, 0, 0);
 106         /* musb_writel(&tx->tx_dummy, 0, 0); */
 107         musb_writel(&tx->tx_complete, 0, ptr);
 108 }
 109 
 110 static void cppi_pool_init(struct cppi *cppi, struct cppi_channel *c)
 111 {
 112         int     j;
 113 
 114         /* initialize channel fields */
 115         c->head = NULL;
 116         c->tail = NULL;
 117         c->last_processed = NULL;
 118         c->channel.status = MUSB_DMA_STATUS_UNKNOWN;
 119         c->controller = cppi;
 120         c->is_rndis = 0;
 121         c->freelist = NULL;
 122 
 123         /* build the BD Free list for the channel */
 124         for (j = 0; j < NUM_TXCHAN_BD + 1; j++) {
 125                 struct cppi_descriptor  *bd;
 126                 dma_addr_t              dma;
 127 
 128                 bd = dma_pool_alloc(cppi->pool, GFP_KERNEL, &dma);
 129                 bd->dma = dma;
 130                 cppi_bd_free(c, bd);
 131         }
 132 }
 133 
 134 static int cppi_channel_abort(struct dma_channel *);
 135 
 136 static void cppi_pool_free(struct cppi_channel *c)
 137 {
 138         struct cppi             *cppi = c->controller;
 139         struct cppi_descriptor  *bd;
 140 
 141         (void) cppi_channel_abort(&c->channel);
 142         c->channel.status = MUSB_DMA_STATUS_UNKNOWN;
 143         c->controller = NULL;
 144 
 145         /* free all its bds */
 146         bd = c->last_processed;
 147         do {
 148                 if (bd)
 149                         dma_pool_free(cppi->pool, bd, bd->dma);
 150                 bd = cppi_bd_alloc(c);
 151         } while (bd);
 152         c->last_processed = NULL;
 153 }
 154 
 155 static void cppi_controller_start(struct cppi *controller)
 156 {
 157         void __iomem    *tibase;
 158         int             i;
 159 
 160         /* do whatever is necessary to start controller */
 161         for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
 162                 controller->tx[i].transmit = true;
 163                 controller->tx[i].index = i;
 164         }
 165         for (i = 0; i < ARRAY_SIZE(controller->rx); i++) {
 166                 controller->rx[i].transmit = false;
 167                 controller->rx[i].index = i;
 168         }
 169 
 170         /* setup BD list on a per channel basis */
 171         for (i = 0; i < ARRAY_SIZE(controller->tx); i++)
 172                 cppi_pool_init(controller, controller->tx + i);
 173         for (i = 0; i < ARRAY_SIZE(controller->rx); i++)
 174                 cppi_pool_init(controller, controller->rx + i);
 175 
 176         tibase =  controller->tibase;
 177         INIT_LIST_HEAD(&controller->tx_complete);
 178 
 179         /* initialise tx/rx channel head pointers to zero */
 180         for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
 181                 struct cppi_channel     *tx_ch = controller->tx + i;
 182                 struct cppi_tx_stateram __iomem *tx;
 183 
 184                 INIT_LIST_HEAD(&tx_ch->tx_complete);
 185 
 186                 tx = tibase + DAVINCI_TXCPPI_STATERAM_OFFSET(i);
 187                 tx_ch->state_ram = tx;
 188                 cppi_reset_tx(tx, 0);
 189         }
 190         for (i = 0; i < ARRAY_SIZE(controller->rx); i++) {
 191                 struct cppi_channel     *rx_ch = controller->rx + i;
 192                 struct cppi_rx_stateram __iomem *rx;
 193 
 194                 INIT_LIST_HEAD(&rx_ch->tx_complete);
 195 
 196                 rx = tibase + DAVINCI_RXCPPI_STATERAM_OFFSET(i);
 197                 rx_ch->state_ram = rx;
 198                 cppi_reset_rx(rx);
 199         }
 200 
 201         /* enable individual cppi channels */
 202         musb_writel(tibase, DAVINCI_TXCPPI_INTENAB_REG,
 203                         DAVINCI_DMA_ALL_CHANNELS_ENABLE);
 204         musb_writel(tibase, DAVINCI_RXCPPI_INTENAB_REG,
 205                         DAVINCI_DMA_ALL_CHANNELS_ENABLE);
 206 
 207         /* enable tx/rx CPPI control */
 208         musb_writel(tibase, DAVINCI_TXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_ENABLE);
 209         musb_writel(tibase, DAVINCI_RXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_ENABLE);
 210 
 211         /* disable RNDIS mode, also host rx RNDIS autorequest */
 212         musb_writel(tibase, DAVINCI_RNDIS_REG, 0);
 213         musb_writel(tibase, DAVINCI_AUTOREQ_REG, 0);
 214 }
 215 
 216 /*
 217  *  Stop DMA controller
 218  *
 219  *  De-Init the DMA controller as necessary.
 220  */
 221 
 222 static void cppi_controller_stop(struct cppi *controller)
 223 {
 224         void __iomem            *tibase;
 225         int                     i;
 226         struct musb             *musb;
 227 
 228         musb = controller->controller.musb;
 229 
 230         tibase = controller->tibase;
 231         /* DISABLE INDIVIDUAL CHANNEL Interrupts */
 232         musb_writel(tibase, DAVINCI_TXCPPI_INTCLR_REG,
 233                         DAVINCI_DMA_ALL_CHANNELS_ENABLE);
 234         musb_writel(tibase, DAVINCI_RXCPPI_INTCLR_REG,
 235                         DAVINCI_DMA_ALL_CHANNELS_ENABLE);
 236 
 237         musb_dbg(musb, "Tearing down RX and TX Channels");
 238         for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
 239                 /* FIXME restructure of txdma to use bds like rxdma */
 240                 controller->tx[i].last_processed = NULL;
 241                 cppi_pool_free(controller->tx + i);
 242         }
 243         for (i = 0; i < ARRAY_SIZE(controller->rx); i++)
 244                 cppi_pool_free(controller->rx + i);
 245 
 246         /* in Tx Case proper teardown is supported. We resort to disabling
 247          * Tx/Rx CPPI after cleanup of Tx channels. Before TX teardown is
 248          * complete TX CPPI cannot be disabled.
 249          */
 250         /*disable tx/rx cppi */
 251         musb_writel(tibase, DAVINCI_TXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_DISABLE);
 252         musb_writel(tibase, DAVINCI_RXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_DISABLE);
 253 }
 254 
 255 /* While dma channel is allocated, we only want the core irqs active
 256  * for fault reports, otherwise we'd get irqs that we don't care about.
 257  * Except for TX irqs, where dma done != fifo empty and reusable ...
 258  *
 259  * NOTE: docs don't say either way, but irq masking **enables** irqs.
 260  *
 261  * REVISIT same issue applies to pure PIO usage too, and non-cppi dma...
 262  */
 263 static inline void core_rxirq_disable(void __iomem *tibase, unsigned epnum)
 264 {
 265         musb_writel(tibase, DAVINCI_USB_INT_MASK_CLR_REG, 1 << (epnum + 8));
 266 }
 267 
 268 static inline void core_rxirq_enable(void __iomem *tibase, unsigned epnum)
 269 {
 270         musb_writel(tibase, DAVINCI_USB_INT_MASK_SET_REG, 1 << (epnum + 8));
 271 }
 272 
 273 
 274 /*
 275  * Allocate a CPPI Channel for DMA.  With CPPI, channels are bound to
 276  * each transfer direction of a non-control endpoint, so allocating
 277  * (and deallocating) is mostly a way to notice bad housekeeping on
 278  * the software side.  We assume the irqs are always active.
 279  */
 280 static struct dma_channel *
 281 cppi_channel_allocate(struct dma_controller *c,
 282                 struct musb_hw_ep *ep, u8 transmit)
 283 {
 284         struct cppi             *controller;
 285         u8                      index;
 286         struct cppi_channel     *cppi_ch;
 287         void __iomem            *tibase;
 288         struct musb             *musb;
 289 
 290         controller = container_of(c, struct cppi, controller);
 291         tibase = controller->tibase;
 292         musb = c->musb;
 293 
 294         /* ep0 doesn't use DMA; remember cppi indices are 0..N-1 */
 295         index = ep->epnum - 1;
 296 
 297         /* return the corresponding CPPI Channel Handle, and
 298          * probably disable the non-CPPI irq until we need it.
 299          */
 300         if (transmit) {
 301                 if (index >= ARRAY_SIZE(controller->tx)) {
 302                         musb_dbg(musb, "no %cX%d CPPI channel", 'T', index);
 303                         return NULL;
 304                 }
 305                 cppi_ch = controller->tx + index;
 306         } else {
 307                 if (index >= ARRAY_SIZE(controller->rx)) {
 308                         musb_dbg(musb, "no %cX%d CPPI channel", 'R', index);
 309                         return NULL;
 310                 }
 311                 cppi_ch = controller->rx + index;
 312                 core_rxirq_disable(tibase, ep->epnum);
 313         }
 314 
 315         /* REVISIT make this an error later once the same driver code works
 316          * with the other DMA engine too
 317          */
 318         if (cppi_ch->hw_ep)
 319                 musb_dbg(musb, "re-allocating DMA%d %cX channel %p",
 320                                 index, transmit ? 'T' : 'R', cppi_ch);
 321         cppi_ch->hw_ep = ep;
 322         cppi_ch->channel.status = MUSB_DMA_STATUS_FREE;
 323         cppi_ch->channel.max_len = 0x7fffffff;
 324 
 325         musb_dbg(musb, "Allocate CPPI%d %cX", index, transmit ? 'T' : 'R');
 326         return &cppi_ch->channel;
 327 }
 328 
 329 /* Release a CPPI Channel.  */
 330 static void cppi_channel_release(struct dma_channel *channel)
 331 {
 332         struct cppi_channel     *c;
 333         void __iomem            *tibase;
 334 
 335         /* REVISIT:  for paranoia, check state and abort if needed... */
 336 
 337         c = container_of(channel, struct cppi_channel, channel);
 338         tibase = c->controller->tibase;
 339         if (!c->hw_ep)
 340                 musb_dbg(c->controller->controller.musb,
 341                         "releasing idle DMA channel %p", c);
 342         else if (!c->transmit)
 343                 core_rxirq_enable(tibase, c->index + 1);
 344 
 345         /* for now, leave its cppi IRQ enabled (we won't trigger it) */
 346         c->hw_ep = NULL;
 347         channel->status = MUSB_DMA_STATUS_UNKNOWN;
 348 }
 349 
 350 /* Context: controller irqlocked */
 351 static void
 352 cppi_dump_rx(int level, struct cppi_channel *c, const char *tag)
 353 {
 354         void __iomem                    *base = c->controller->mregs;
 355         struct cppi_rx_stateram __iomem *rx = c->state_ram;
 356 
 357         musb_ep_select(base, c->index + 1);
 358 
 359         musb_dbg(c->controller->controller.musb,
 360                 "RX DMA%d%s: %d left, csr %04x, "
 361                 "%08x H%08x S%08x C%08x, "
 362                 "B%08x L%08x %08x .. %08x",
 363                 c->index, tag,
 364                 musb_readl(c->controller->tibase,
 365                         DAVINCI_RXCPPI_BUFCNT0_REG + 4 * c->index),
 366                 musb_readw(c->hw_ep->regs, MUSB_RXCSR),
 367 
 368                 musb_readl(&rx->rx_skipbytes, 0),
 369                 musb_readl(&rx->rx_head, 0),
 370                 musb_readl(&rx->rx_sop, 0),
 371                 musb_readl(&rx->rx_current, 0),
 372 
 373                 musb_readl(&rx->rx_buf_current, 0),
 374                 musb_readl(&rx->rx_len_len, 0),
 375                 musb_readl(&rx->rx_cnt_cnt, 0),
 376                 musb_readl(&rx->rx_complete, 0)
 377                 );
 378 }
 379 
 380 /* Context: controller irqlocked */
 381 static void
 382 cppi_dump_tx(int level, struct cppi_channel *c, const char *tag)
 383 {
 384         void __iomem                    *base = c->controller->mregs;
 385         struct cppi_tx_stateram __iomem *tx = c->state_ram;
 386 
 387         musb_ep_select(base, c->index + 1);
 388 
 389         musb_dbg(c->controller->controller.musb,
 390                 "TX DMA%d%s: csr %04x, "
 391                 "H%08x S%08x C%08x %08x, "
 392                 "F%08x L%08x .. %08x",
 393                 c->index, tag,
 394                 musb_readw(c->hw_ep->regs, MUSB_TXCSR),
 395 
 396                 musb_readl(&tx->tx_head, 0),
 397                 musb_readl(&tx->tx_buf, 0),
 398                 musb_readl(&tx->tx_current, 0),
 399                 musb_readl(&tx->tx_buf_current, 0),
 400 
 401                 musb_readl(&tx->tx_info, 0),
 402                 musb_readl(&tx->tx_rem_len, 0),
 403                 /* dummy/unused word 6 */
 404                 musb_readl(&tx->tx_complete, 0)
 405                 );
 406 }
 407 
 408 /* Context: controller irqlocked */
 409 static inline void
 410 cppi_rndis_update(struct cppi_channel *c, int is_rx,
 411                 void __iomem *tibase, int is_rndis)
 412 {
 413         /* we may need to change the rndis flag for this cppi channel */
 414         if (c->is_rndis != is_rndis) {
 415                 u32     value = musb_readl(tibase, DAVINCI_RNDIS_REG);
 416                 u32     temp = 1 << (c->index);
 417 
 418                 if (is_rx)
 419                         temp <<= 16;
 420                 if (is_rndis)
 421                         value |= temp;
 422                 else
 423                         value &= ~temp;
 424                 musb_writel(tibase, DAVINCI_RNDIS_REG, value);
 425                 c->is_rndis = is_rndis;
 426         }
 427 }
 428 
 429 static void cppi_dump_rxbd(const char *tag, struct cppi_descriptor *bd)
 430 {
 431         pr_debug("RXBD/%s %08x: "
 432                         "nxt %08x buf %08x off.blen %08x opt.plen %08x\n",
 433                         tag, bd->dma,
 434                         bd->hw_next, bd->hw_bufp, bd->hw_off_len,
 435                         bd->hw_options);
 436 }
 437 
 438 static void cppi_dump_rxq(int level, const char *tag, struct cppi_channel *rx)
 439 {
 440         struct cppi_descriptor  *bd;
 441 
 442         cppi_dump_rx(level, rx, tag);
 443         if (rx->last_processed)
 444                 cppi_dump_rxbd("last", rx->last_processed);
 445         for (bd = rx->head; bd; bd = bd->next)
 446                 cppi_dump_rxbd("active", bd);
 447 }
 448 
 449 
 450 /* NOTE:  DaVinci autoreq is ignored except for host side "RNDIS" mode RX;
 451  * so we won't ever use it (see "CPPI RX Woes" below).
 452  */
 453 static inline int cppi_autoreq_update(struct cppi_channel *rx,
 454                 void __iomem *tibase, int onepacket, unsigned n_bds)
 455 {
 456         u32     val;
 457 
 458 #ifdef  RNDIS_RX_IS_USABLE
 459         u32     tmp;
 460         /* assert(is_host_active(musb)) */
 461 
 462         /* start from "AutoReq never" */
 463         tmp = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
 464         val = tmp & ~((0x3) << (rx->index * 2));
 465 
 466         /* HCD arranged reqpkt for packet #1.  we arrange int
 467          * for all but the last one, maybe in two segments.
 468          */
 469         if (!onepacket) {
 470 #if 0
 471                 /* use two segments, autoreq "all" then the last "never" */
 472                 val |= ((0x3) << (rx->index * 2));
 473                 n_bds--;
 474 #else
 475                 /* one segment, autoreq "all-but-last" */
 476                 val |= ((0x1) << (rx->index * 2));
 477 #endif
 478         }
 479 
 480         if (val != tmp) {
 481                 int n = 100;
 482 
 483                 /* make sure that autoreq is updated before continuing */
 484                 musb_writel(tibase, DAVINCI_AUTOREQ_REG, val);
 485                 do {
 486                         tmp = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
 487                         if (tmp == val)
 488                                 break;
 489                         cpu_relax();
 490                 } while (n-- > 0);
 491         }
 492 #endif
 493 
 494         /* REQPKT is turned off after each segment */
 495         if (n_bds && rx->channel.actual_len) {
 496                 void __iomem    *regs = rx->hw_ep->regs;
 497 
 498                 val = musb_readw(regs, MUSB_RXCSR);
 499                 if (!(val & MUSB_RXCSR_H_REQPKT)) {
 500                         val |= MUSB_RXCSR_H_REQPKT | MUSB_RXCSR_H_WZC_BITS;
 501                         musb_writew(regs, MUSB_RXCSR, val);
 502                         /* flush writebuffer */
 503                         val = musb_readw(regs, MUSB_RXCSR);
 504                 }
 505         }
 506         return n_bds;
 507 }
 508 
 509 
 510 /* Buffer enqueuing Logic:
 511  *
 512  *  - RX builds new queues each time, to help handle routine "early
 513  *    termination" cases (faults, including errors and short reads)
 514  *    more correctly.
 515  *
 516  *  - for now, TX reuses the same queue of BDs every time
 517  *
 518  * REVISIT long term, we want a normal dynamic model.
 519  * ... the goal will be to append to the
 520  * existing queue, processing completed "dma buffers" (segments) on the fly.
 521  *
 522  * Otherwise we force an IRQ latency between requests, which slows us a lot
 523  * (especially in "transparent" dma).  Unfortunately that model seems to be
 524  * inherent in the DMA model from the Mentor code, except in the rare case
 525  * of transfers big enough (~128+ KB) that we could append "middle" segments
 526  * in the TX paths.  (RX can't do this, see below.)
 527  *
 528  * That's true even in the CPPI- friendly iso case, where most urbs have
 529  * several small segments provided in a group and where the "packet at a time"
 530  * "transparent" DMA model is always correct, even on the RX side.
 531  */
 532 
 533 /*
 534  * CPPI TX:
 535  * ========
 536  * TX is a lot more reasonable than RX; it doesn't need to run in
 537  * irq-per-packet mode very often.  RNDIS mode seems to behave too
 538  * (except how it handles the exactly-N-packets case).  Building a
 539  * txdma queue with multiple requests (urb or usb_request) looks
 540  * like it would work ... but fault handling would need much testing.
 541  *
 542  * The main issue with TX mode RNDIS relates to transfer lengths that
 543  * are an exact multiple of the packet length.  It appears that there's
 544  * a hiccup in that case (maybe the DMA completes before the ZLP gets
 545  * written?) boiling down to not being able to rely on CPPI writing any
 546  * terminating zero length packet before the next transfer is written.
 547  * So that's punted to PIO; better yet, gadget drivers can avoid it.
 548  *
 549  * Plus, there's allegedly an undocumented constraint that rndis transfer
 550  * length be a multiple of 64 bytes ... but the chip doesn't act that
 551  * way, and we really don't _want_ that behavior anyway.
 552  *
 553  * On TX, "transparent" mode works ... although experiments have shown
 554  * problems trying to use the SOP/EOP bits in different USB packets.
 555  *
 556  * REVISIT try to handle terminating zero length packets using CPPI
 557  * instead of doing it by PIO after an IRQ.  (Meanwhile, make Ethernet
 558  * links avoid that issue by forcing them to avoid zlps.)
 559  */
 560 static void
 561 cppi_next_tx_segment(struct musb *musb, struct cppi_channel *tx)
 562 {
 563         unsigned                maxpacket = tx->maxpacket;
 564         dma_addr_t              addr = tx->buf_dma + tx->offset;
 565         size_t                  length = tx->buf_len - tx->offset;
 566         struct cppi_descriptor  *bd;
 567         unsigned                n_bds;
 568         unsigned                i;
 569         struct cppi_tx_stateram __iomem *tx_ram = tx->state_ram;
 570         int                     rndis;
 571 
 572         /* TX can use the CPPI "rndis" mode, where we can probably fit this
 573          * transfer in one BD and one IRQ.  The only time we would NOT want
 574          * to use it is when hardware constraints prevent it, or if we'd
 575          * trigger the "send a ZLP?" confusion.
 576          */
 577         rndis = (maxpacket & 0x3f) == 0
 578                 && length > maxpacket
 579                 && length < 0xffff
 580                 && (length % maxpacket) != 0;
 581 
 582         if (rndis) {
 583                 maxpacket = length;
 584                 n_bds = 1;
 585         } else {
 586                 if (length)
 587                         n_bds = DIV_ROUND_UP(length, maxpacket);
 588                 else
 589                         n_bds = 1;
 590                 n_bds = min(n_bds, (unsigned) NUM_TXCHAN_BD);
 591                 length = min(n_bds * maxpacket, length);
 592         }
 593 
 594         musb_dbg(musb, "TX DMA%d, pktSz %d %s bds %d dma 0x%llx len %u",
 595                         tx->index,
 596                         maxpacket,
 597                         rndis ? "rndis" : "transparent",
 598                         n_bds,
 599                         (unsigned long long)addr, length);
 600 
 601         cppi_rndis_update(tx, 0, musb->ctrl_base, rndis);
 602 
 603         /* assuming here that channel_program is called during
 604          * transfer initiation ... current code maintains state
 605          * for one outstanding request only (no queues, not even
 606          * the implicit ones of an iso urb).
 607          */
 608 
 609         bd = tx->freelist;
 610         tx->head = bd;
 611         tx->last_processed = NULL;
 612 
 613         /* FIXME use BD pool like RX side does, and just queue
 614          * the minimum number for this request.
 615          */
 616 
 617         /* Prepare queue of BDs first, then hand it to hardware.
 618          * All BDs except maybe the last should be of full packet
 619          * size; for RNDIS there _is_ only that last packet.
 620          */
 621         for (i = 0; i < n_bds; ) {
 622                 if (++i < n_bds && bd->next)
 623                         bd->hw_next = bd->next->dma;
 624                 else
 625                         bd->hw_next = 0;
 626 
 627                 bd->hw_bufp = tx->buf_dma + tx->offset;
 628 
 629                 /* FIXME set EOP only on the last packet,
 630                  * SOP only on the first ... avoid IRQs
 631                  */
 632                 if ((tx->offset + maxpacket) <= tx->buf_len) {
 633                         tx->offset += maxpacket;
 634                         bd->hw_off_len = maxpacket;
 635                         bd->hw_options = CPPI_SOP_SET | CPPI_EOP_SET
 636                                 | CPPI_OWN_SET | maxpacket;
 637                 } else {
 638                         /* only this one may be a partial USB Packet */
 639                         u32             partial_len;
 640 
 641                         partial_len = tx->buf_len - tx->offset;
 642                         tx->offset = tx->buf_len;
 643                         bd->hw_off_len = partial_len;
 644 
 645                         bd->hw_options = CPPI_SOP_SET | CPPI_EOP_SET
 646                                 | CPPI_OWN_SET | partial_len;
 647                         if (partial_len == 0)
 648                                 bd->hw_options |= CPPI_ZERO_SET;
 649                 }
 650 
 651                 musb_dbg(musb, "TXBD %p: nxt %08x buf %08x len %04x opt %08x",
 652                                 bd, bd->hw_next, bd->hw_bufp,
 653                                 bd->hw_off_len, bd->hw_options);
 654 
 655                 /* update the last BD enqueued to the list */
 656                 tx->tail = bd;
 657                 bd = bd->next;
 658         }
 659 
 660         /* BDs live in DMA-coherent memory, but writes might be pending */
 661         cpu_drain_writebuffer();
 662 
 663         /* Write to the HeadPtr in state RAM to trigger */
 664         musb_writel(&tx_ram->tx_head, 0, (u32)tx->freelist->dma);
 665 
 666         cppi_dump_tx(5, tx, "/S");
 667 }
 668 
 669 /*
 670  * CPPI RX Woes:
 671  * =============
 672  * Consider a 1KB bulk RX buffer in two scenarios:  (a) it's fed two 300 byte
 673  * packets back-to-back, and (b) it's fed two 512 byte packets back-to-back.
 674  * (Full speed transfers have similar scenarios.)
 675  *
 676  * The correct behavior for Linux is that (a) fills the buffer with 300 bytes,
 677  * and the next packet goes into a buffer that's queued later; while (b) fills
 678  * the buffer with 1024 bytes.  How to do that with CPPI?
 679  *
 680  * - RX queues in "rndis" mode -- one single BD -- handle (a) correctly, but
 681  *   (b) loses **BADLY** because nothing (!) happens when that second packet
 682  *   fills the buffer, much less when a third one arrives.  (Which makes this
 683  *   not a "true" RNDIS mode.  In the RNDIS protocol short-packet termination
 684  *   is optional, and it's fine if peripherals -- not hosts! -- pad messages
 685  *   out to end-of-buffer.  Standard PCI host controller DMA descriptors
 686  *   implement that mode by default ... which is no accident.)
 687  *
 688  * - RX queues in "transparent" mode -- two BDs with 512 bytes each -- have
 689  *   converse problems:  (b) is handled right, but (a) loses badly.  CPPI RX
 690  *   ignores SOP/EOP markings and processes both of those BDs; so both packets
 691  *   are loaded into the buffer (with a 212 byte gap between them), and the next
 692  *   buffer queued will NOT get its 300 bytes of data. (It seems like SOP/EOP
 693  *   are intended as outputs for RX queues, not inputs...)
 694  *
 695  * - A variant of "transparent" mode -- one BD at a time -- is the only way to
 696  *   reliably make both cases work, with software handling both cases correctly
 697  *   and at the significant penalty of needing an IRQ per packet.  (The lack of
 698  *   I/O overlap can be slightly ameliorated by enabling double buffering.)
 699  *
 700  * So how to get rid of IRQ-per-packet?  The transparent multi-BD case could
 701  * be used in special cases like mass storage, which sets URB_SHORT_NOT_OK
 702  * (or maybe its peripheral side counterpart) to flag (a) scenarios as errors
 703  * with guaranteed driver level fault recovery and scrubbing out what's left
 704  * of that garbaged datastream.
 705  *
 706  * But there seems to be no way to identify the cases where CPPI RNDIS mode
 707  * is appropriate -- which do NOT include RNDIS host drivers, but do include
 708  * the CDC Ethernet driver! -- and the documentation is incomplete/wrong.
 709  * So we can't _ever_ use RX RNDIS mode ... except by using a heuristic
 710  * that applies best on the peripheral side (and which could fail rudely).
 711  *
 712  * Leaving only "transparent" mode; we avoid multi-bd modes in almost all
 713  * cases other than mass storage class.  Otherwise we're correct but slow,
 714  * since CPPI penalizes our need for a "true RNDIS" default mode.
 715  */
 716 
 717 
 718 /* Heuristic, intended to kick in for ethernet/rndis peripheral ONLY
 719  *
 720  * IFF
 721  *  (a) peripheral mode ... since rndis peripherals could pad their
 722  *      writes to hosts, causing i/o failure; or we'd have to cope with
 723  *      a largely unknowable variety of host side protocol variants
 724  *  (b) and short reads are NOT errors ... since full reads would
 725  *      cause those same i/o failures
 726  *  (c) and read length is
 727  *      - less than 64KB (max per cppi descriptor)
 728  *      - not a multiple of 4096 (g_zero default, full reads typical)
 729  *      - N (>1) packets long, ditto (full reads not EXPECTED)
 730  * THEN
 731  *   try rx rndis mode
 732  *
 733  * Cost of heuristic failing:  RXDMA wedges at the end of transfers that
 734  * fill out the whole buffer.  Buggy host side usb network drivers could
 735  * trigger that, but "in the field" such bugs seem to be all but unknown.
 736  *
 737  * So this module parameter lets the heuristic be disabled.  When using
 738  * gadgetfs, the heuristic will probably need to be disabled.
 739  */
 740 static bool cppi_rx_rndis = 1;
 741 
 742 module_param(cppi_rx_rndis, bool, 0);
 743 MODULE_PARM_DESC(cppi_rx_rndis, "enable/disable RX RNDIS heuristic");
 744 
 745 
 746 /**
 747  * cppi_next_rx_segment - dma read for the next chunk of a buffer
 748  * @musb: the controller
 749  * @rx: dma channel
 750  * @onepacket: true unless caller treats short reads as errors, and
 751  *      performs fault recovery above usbcore.
 752  * Context: controller irqlocked
 753  *
 754  * See above notes about why we can't use multi-BD RX queues except in
 755  * rare cases (mass storage class), and can never use the hardware "rndis"
 756  * mode (since it's not a "true" RNDIS mode) with complete safety..
 757  *
 758  * It's ESSENTIAL that callers specify "onepacket" mode unless they kick in
 759  * code to recover from corrupted datastreams after each short transfer.
 760  */
 761 static void
 762 cppi_next_rx_segment(struct musb *musb, struct cppi_channel *rx, int onepacket)
 763 {
 764         unsigned                maxpacket = rx->maxpacket;
 765         dma_addr_t              addr = rx->buf_dma + rx->offset;
 766         size_t                  length = rx->buf_len - rx->offset;
 767         struct cppi_descriptor  *bd, *tail;
 768         unsigned                n_bds;
 769         unsigned                i;
 770         void __iomem            *tibase = musb->ctrl_base;
 771         int                     is_rndis = 0;
 772         struct cppi_rx_stateram __iomem *rx_ram = rx->state_ram;
 773         struct cppi_descriptor  *d;
 774 
 775         if (onepacket) {
 776                 /* almost every USB driver, host or peripheral side */
 777                 n_bds = 1;
 778 
 779                 /* maybe apply the heuristic above */
 780                 if (cppi_rx_rndis
 781                                 && is_peripheral_active(musb)
 782                                 && length > maxpacket
 783                                 && (length & ~0xffff) == 0
 784                                 && (length & 0x0fff) != 0
 785                                 && (length & (maxpacket - 1)) == 0) {
 786                         maxpacket = length;
 787                         is_rndis = 1;
 788                 }
 789         } else {
 790                 /* virtually nothing except mass storage class */
 791                 if (length > 0xffff) {
 792                         n_bds = 0xffff / maxpacket;
 793                         length = n_bds * maxpacket;
 794                 } else {
 795                         n_bds = DIV_ROUND_UP(length, maxpacket);
 796                 }
 797                 if (n_bds == 1)
 798                         onepacket = 1;
 799                 else
 800                         n_bds = min(n_bds, (unsigned) NUM_RXCHAN_BD);
 801         }
 802 
 803         /* In host mode, autorequest logic can generate some IN tokens; it's
 804          * tricky since we can't leave REQPKT set in RXCSR after the transfer
 805          * finishes. So:  multipacket transfers involve two or more segments.
 806          * And always at least two IRQs ... RNDIS mode is not an option.
 807          */
 808         if (is_host_active(musb))
 809                 n_bds = cppi_autoreq_update(rx, tibase, onepacket, n_bds);
 810 
 811         cppi_rndis_update(rx, 1, musb->ctrl_base, is_rndis);
 812 
 813         length = min(n_bds * maxpacket, length);
 814 
 815         musb_dbg(musb, "RX DMA%d seg, maxp %d %s bds %d (cnt %d) "
 816                         "dma 0x%llx len %u %u/%u",
 817                         rx->index, maxpacket,
 818                         onepacket
 819                                 ? (is_rndis ? "rndis" : "onepacket")
 820                                 : "multipacket",
 821                         n_bds,
 822                         musb_readl(tibase,
 823                                 DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
 824                                         & 0xffff,
 825                         (unsigned long long)addr, length,
 826                         rx->channel.actual_len, rx->buf_len);
 827 
 828         /* only queue one segment at a time, since the hardware prevents
 829          * correct queue shutdown after unexpected short packets
 830          */
 831         bd = cppi_bd_alloc(rx);
 832         rx->head = bd;
 833 
 834         /* Build BDs for all packets in this segment */
 835         for (i = 0, tail = NULL; bd && i < n_bds; i++, tail = bd) {
 836                 u32     bd_len;
 837 
 838                 if (i) {
 839                         bd = cppi_bd_alloc(rx);
 840                         if (!bd)
 841                                 break;
 842                         tail->next = bd;
 843                         tail->hw_next = bd->dma;
 844                 }
 845                 bd->hw_next = 0;
 846 
 847                 /* all but the last packet will be maxpacket size */
 848                 if (maxpacket < length)
 849                         bd_len = maxpacket;
 850                 else
 851                         bd_len = length;
 852 
 853                 bd->hw_bufp = addr;
 854                 addr += bd_len;
 855                 rx->offset += bd_len;
 856 
 857                 bd->hw_off_len = (0 /*offset*/ << 16) + bd_len;
 858                 bd->buflen = bd_len;
 859 
 860                 bd->hw_options = CPPI_OWN_SET | (i == 0 ? length : 0);
 861                 length -= bd_len;
 862         }
 863 
 864         /* we always expect at least one reusable BD! */
 865         if (!tail) {
 866                 WARNING("rx dma%d -- no BDs? need %d\n", rx->index, n_bds);
 867                 return;
 868         } else if (i < n_bds)
 869                 WARNING("rx dma%d -- only %d of %d BDs\n", rx->index, i, n_bds);
 870 
 871         tail->next = NULL;
 872         tail->hw_next = 0;
 873 
 874         bd = rx->head;
 875         rx->tail = tail;
 876 
 877         /* short reads and other faults should terminate this entire
 878          * dma segment.  we want one "dma packet" per dma segment, not
 879          * one per USB packet, terminating the whole queue at once...
 880          * NOTE that current hardware seems to ignore SOP and EOP.
 881          */
 882         bd->hw_options |= CPPI_SOP_SET;
 883         tail->hw_options |= CPPI_EOP_SET;
 884 
 885         for (d = rx->head; d; d = d->next)
 886                 cppi_dump_rxbd("S", d);
 887 
 888         /* in case the preceding transfer left some state... */
 889         tail = rx->last_processed;
 890         if (tail) {
 891                 tail->next = bd;
 892                 tail->hw_next = bd->dma;
 893         }
 894 
 895         core_rxirq_enable(tibase, rx->index + 1);
 896 
 897         /* BDs live in DMA-coherent memory, but writes might be pending */
 898         cpu_drain_writebuffer();
 899 
 900         /* REVISIT specs say to write this AFTER the BUFCNT register
 901          * below ... but that loses badly.
 902          */
 903         musb_writel(&rx_ram->rx_head, 0, bd->dma);
 904 
 905         /* bufferCount must be at least 3, and zeroes on completion
 906          * unless it underflows below zero, or stops at two, or keeps
 907          * growing ... grr.
 908          */
 909         i = musb_readl(tibase,
 910                         DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
 911                         & 0xffff;
 912 
 913         if (!i)
 914                 musb_writel(tibase,
 915                         DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
 916                         n_bds + 2);
 917         else if (n_bds > (i - 3))
 918                 musb_writel(tibase,
 919                         DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
 920                         n_bds - (i - 3));
 921 
 922         i = musb_readl(tibase,
 923                         DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
 924                         & 0xffff;
 925         if (i < (2 + n_bds)) {
 926                 musb_dbg(musb, "bufcnt%d underrun - %d (for %d)",
 927                                         rx->index, i, n_bds);
 928                 musb_writel(tibase,
 929                         DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
 930                         n_bds + 2);
 931         }
 932 
 933         cppi_dump_rx(4, rx, "/S");
 934 }
 935 
 936 /**
 937  * cppi_channel_program - program channel for data transfer
 938  * @ch: the channel
 939  * @maxpacket: max packet size
 940  * @mode: For RX, 1 unless the usb protocol driver promised to treat
 941  *      all short reads as errors and kick in high level fault recovery.
 942  *      For TX, ignored because of RNDIS mode races/glitches.
 943  * @dma_addr: dma address of buffer
 944  * @len: length of buffer
 945  * Context: controller irqlocked
 946  */
 947 static int cppi_channel_program(struct dma_channel *ch,
 948                 u16 maxpacket, u8 mode,
 949                 dma_addr_t dma_addr, u32 len)
 950 {
 951         struct cppi_channel     *cppi_ch;
 952         struct cppi             *controller;
 953         struct musb             *musb;
 954 
 955         cppi_ch = container_of(ch, struct cppi_channel, channel);
 956         controller = cppi_ch->controller;
 957         musb = controller->controller.musb;
 958 
 959         switch (ch->status) {
 960         case MUSB_DMA_STATUS_BUS_ABORT:
 961         case MUSB_DMA_STATUS_CORE_ABORT:
 962                 /* fault irq handler should have handled cleanup */
 963                 WARNING("%cX DMA%d not cleaned up after abort!\n",
 964                                 cppi_ch->transmit ? 'T' : 'R',
 965                                 cppi_ch->index);
 966                 /* WARN_ON(1); */
 967                 break;
 968         case MUSB_DMA_STATUS_BUSY:
 969                 WARNING("program active channel?  %cX DMA%d\n",
 970                                 cppi_ch->transmit ? 'T' : 'R',
 971                                 cppi_ch->index);
 972                 /* WARN_ON(1); */
 973                 break;
 974         case MUSB_DMA_STATUS_UNKNOWN:
 975                 musb_dbg(musb, "%cX DMA%d not allocated!",
 976                                 cppi_ch->transmit ? 'T' : 'R',
 977                                 cppi_ch->index);
 978                 /* FALLTHROUGH */
 979         case MUSB_DMA_STATUS_FREE:
 980                 break;
 981         }
 982 
 983         ch->status = MUSB_DMA_STATUS_BUSY;
 984 
 985         /* set transfer parameters, then queue up its first segment */
 986         cppi_ch->buf_dma = dma_addr;
 987         cppi_ch->offset = 0;
 988         cppi_ch->maxpacket = maxpacket;
 989         cppi_ch->buf_len = len;
 990         cppi_ch->channel.actual_len = 0;
 991 
 992         /* TX channel? or RX? */
 993         if (cppi_ch->transmit)
 994                 cppi_next_tx_segment(musb, cppi_ch);
 995         else
 996                 cppi_next_rx_segment(musb, cppi_ch, mode);
 997 
 998         return true;
 999 }
1000 
1001 static bool cppi_rx_scan(struct cppi *cppi, unsigned ch)
1002 {
1003         struct cppi_channel             *rx = &cppi->rx[ch];
1004         struct cppi_rx_stateram __iomem *state = rx->state_ram;
1005         struct cppi_descriptor          *bd;
1006         struct cppi_descriptor          *last = rx->last_processed;
1007         bool                            completed = false;
1008         bool                            acked = false;
1009         int                             i;
1010         dma_addr_t                      safe2ack;
1011         void __iomem                    *regs = rx->hw_ep->regs;
1012         struct musb                     *musb = cppi->controller.musb;
1013 
1014         cppi_dump_rx(6, rx, "/K");
1015 
1016         bd = last ? last->next : rx->head;
1017         if (!bd)
1018                 return false;
1019 
1020         /* run through all completed BDs */
1021         for (i = 0, safe2ack = musb_readl(&state->rx_complete, 0);
1022                         (safe2ack || completed) && bd && i < NUM_RXCHAN_BD;
1023                         i++, bd = bd->next) {
1024                 u16     len;
1025 
1026                 /* catch latest BD writes from CPPI */
1027                 rmb();
1028                 if (!completed && (bd->hw_options & CPPI_OWN_SET))
1029                         break;
1030 
1031                 musb_dbg(musb, "C/RXBD %llx: nxt %08x buf %08x "
1032                         "off.len %08x opt.len %08x (%d)",
1033                         (unsigned long long)bd->dma, bd->hw_next, bd->hw_bufp,
1034                         bd->hw_off_len, bd->hw_options,
1035                         rx->channel.actual_len);
1036 
1037                 /* actual packet received length */
1038                 if ((bd->hw_options & CPPI_SOP_SET) && !completed)
1039                         len = bd->hw_off_len & CPPI_RECV_PKTLEN_MASK;
1040                 else
1041                         len = 0;
1042 
1043                 if (bd->hw_options & CPPI_EOQ_MASK)
1044                         completed = true;
1045 
1046                 if (!completed && len < bd->buflen) {
1047                         /* NOTE:  when we get a short packet, RXCSR_H_REQPKT
1048                          * must have been cleared, and no more DMA packets may
1049                          * active be in the queue... TI docs didn't say, but
1050                          * CPPI ignores those BDs even though OWN is still set.
1051                          */
1052                         completed = true;
1053                         musb_dbg(musb, "rx short %d/%d (%d)",
1054                                         len, bd->buflen,
1055                                         rx->channel.actual_len);
1056                 }
1057 
1058                 /* If we got here, we expect to ack at least one BD; meanwhile
1059                  * CPPI may completing other BDs while we scan this list...
1060                  *
1061                  * RACE: we can notice OWN cleared before CPPI raises the
1062                  * matching irq by writing that BD as the completion pointer.
1063                  * In such cases, stop scanning and wait for the irq, avoiding
1064                  * lost acks and states where BD ownership is unclear.
1065                  */
1066                 if (bd->dma == safe2ack) {
1067                         musb_writel(&state->rx_complete, 0, safe2ack);
1068                         safe2ack = musb_readl(&state->rx_complete, 0);
1069                         acked = true;
1070                         if (bd->dma == safe2ack)
1071                                 safe2ack = 0;
1072                 }
1073 
1074                 rx->channel.actual_len += len;
1075 
1076                 cppi_bd_free(rx, last);
1077                 last = bd;
1078 
1079                 /* stop scanning on end-of-segment */
1080                 if (bd->hw_next == 0)
1081                         completed = true;
1082         }
1083         rx->last_processed = last;
1084 
1085         /* dma abort, lost ack, or ... */
1086         if (!acked && last) {
1087                 int     csr;
1088 
1089                 if (safe2ack == 0 || safe2ack == rx->last_processed->dma)
1090                         musb_writel(&state->rx_complete, 0, safe2ack);
1091                 if (safe2ack == 0) {
1092                         cppi_bd_free(rx, last);
1093                         rx->last_processed = NULL;
1094 
1095                         /* if we land here on the host side, H_REQPKT will
1096                          * be clear and we need to restart the queue...
1097                          */
1098                         WARN_ON(rx->head);
1099                 }
1100                 musb_ep_select(cppi->mregs, rx->index + 1);
1101                 csr = musb_readw(regs, MUSB_RXCSR);
1102                 if (csr & MUSB_RXCSR_DMAENAB) {
1103                         musb_dbg(musb, "list%d %p/%p, last %llx%s, csr %04x",
1104                                 rx->index,
1105                                 rx->head, rx->tail,
1106                                 rx->last_processed
1107                                         ? (unsigned long long)
1108                                                 rx->last_processed->dma
1109                                         : 0,
1110                                 completed ? ", completed" : "",
1111                                 csr);
1112                         cppi_dump_rxq(4, "/what?", rx);
1113                 }
1114         }
1115         if (!completed) {
1116                 int     csr;
1117 
1118                 rx->head = bd;
1119 
1120                 /* REVISIT seems like "autoreq all but EOP" doesn't...
1121                  * setting it here "should" be racey, but seems to work
1122                  */
1123                 csr = musb_readw(rx->hw_ep->regs, MUSB_RXCSR);
1124                 if (is_host_active(cppi->controller.musb)
1125                                 && bd
1126                                 && !(csr & MUSB_RXCSR_H_REQPKT)) {
1127                         csr |= MUSB_RXCSR_H_REQPKT;
1128                         musb_writew(regs, MUSB_RXCSR,
1129                                         MUSB_RXCSR_H_WZC_BITS | csr);
1130                         csr = musb_readw(rx->hw_ep->regs, MUSB_RXCSR);
1131                 }
1132         } else {
1133                 rx->head = NULL;
1134                 rx->tail = NULL;
1135         }
1136 
1137         cppi_dump_rx(6, rx, completed ? "/completed" : "/cleaned");
1138         return completed;
1139 }
1140 
1141 irqreturn_t cppi_interrupt(int irq, void *dev_id)
1142 {
1143         struct musb             *musb = dev_id;
1144         struct cppi             *cppi;
1145         void __iomem            *tibase;
1146         struct musb_hw_ep       *hw_ep = NULL;
1147         u32                     rx, tx;
1148         int                     i, index;
1149         unsigned long           uninitialized_var(flags);
1150 
1151         cppi = container_of(musb->dma_controller, struct cppi, controller);
1152         if (cppi->irq)
1153                 spin_lock_irqsave(&musb->lock, flags);
1154 
1155         tibase = musb->ctrl_base;
1156 
1157         tx = musb_readl(tibase, DAVINCI_TXCPPI_MASKED_REG);
1158         rx = musb_readl(tibase, DAVINCI_RXCPPI_MASKED_REG);
1159 
1160         if (!tx && !rx) {
1161                 if (cppi->irq)
1162                         spin_unlock_irqrestore(&musb->lock, flags);
1163                 return IRQ_NONE;
1164         }
1165 
1166         musb_dbg(musb, "CPPI IRQ Tx%x Rx%x", tx, rx);
1167 
1168         /* process TX channels */
1169         for (index = 0; tx; tx = tx >> 1, index++) {
1170                 struct cppi_channel             *tx_ch;
1171                 struct cppi_tx_stateram __iomem *tx_ram;
1172                 bool                            completed = false;
1173                 struct cppi_descriptor          *bd;
1174 
1175                 if (!(tx & 1))
1176                         continue;
1177 
1178                 tx_ch = cppi->tx + index;
1179                 tx_ram = tx_ch->state_ram;
1180 
1181                 /* FIXME  need a cppi_tx_scan() routine, which
1182                  * can also be called from abort code
1183                  */
1184 
1185                 cppi_dump_tx(5, tx_ch, "/E");
1186 
1187                 bd = tx_ch->head;
1188 
1189                 /*
1190                  * If Head is null then this could mean that a abort interrupt
1191                  * that needs to be acknowledged.
1192                  */
1193                 if (NULL == bd) {
1194                         musb_dbg(musb, "null BD");
1195                         musb_writel(&tx_ram->tx_complete, 0, 0);
1196                         continue;
1197                 }
1198 
1199                 /* run through all completed BDs */
1200                 for (i = 0; !completed && bd && i < NUM_TXCHAN_BD;
1201                                 i++, bd = bd->next) {
1202                         u16     len;
1203 
1204                         /* catch latest BD writes from CPPI */
1205                         rmb();
1206                         if (bd->hw_options & CPPI_OWN_SET)
1207                                 break;
1208 
1209                         musb_dbg(musb, "C/TXBD %p n %x b %x off %x opt %x",
1210                                         bd, bd->hw_next, bd->hw_bufp,
1211                                         bd->hw_off_len, bd->hw_options);
1212 
1213                         len = bd->hw_off_len & CPPI_BUFFER_LEN_MASK;
1214                         tx_ch->channel.actual_len += len;
1215 
1216                         tx_ch->last_processed = bd;
1217 
1218                         /* write completion register to acknowledge
1219                          * processing of completed BDs, and possibly
1220                          * release the IRQ; EOQ might not be set ...
1221                          *
1222                          * REVISIT use the same ack strategy as rx
1223                          *
1224                          * REVISIT have observed bit 18 set; huh??
1225                          */
1226                         /* if ((bd->hw_options & CPPI_EOQ_MASK)) */
1227                                 musb_writel(&tx_ram->tx_complete, 0, bd->dma);
1228 
1229                         /* stop scanning on end-of-segment */
1230                         if (bd->hw_next == 0)
1231                                 completed = true;
1232                 }
1233 
1234                 /* on end of segment, maybe go to next one */
1235                 if (completed) {
1236                         /* cppi_dump_tx(4, tx_ch, "/complete"); */
1237 
1238                         /* transfer more, or report completion */
1239                         if (tx_ch->offset >= tx_ch->buf_len) {
1240                                 tx_ch->head = NULL;
1241                                 tx_ch->tail = NULL;
1242                                 tx_ch->channel.status = MUSB_DMA_STATUS_FREE;
1243 
1244                                 hw_ep = tx_ch->hw_ep;
1245 
1246                                 musb_dma_completion(musb, index + 1, 1);
1247 
1248                         } else {
1249                                 /* Bigger transfer than we could fit in
1250                                  * that first batch of descriptors...
1251                                  */
1252                                 cppi_next_tx_segment(musb, tx_ch);
1253                         }
1254                 } else
1255                         tx_ch->head = bd;
1256         }
1257 
1258         /* Start processing the RX block */
1259         for (index = 0; rx; rx = rx >> 1, index++) {
1260 
1261                 if (rx & 1) {
1262                         struct cppi_channel             *rx_ch;
1263 
1264                         rx_ch = cppi->rx + index;
1265 
1266                         /* let incomplete dma segments finish */
1267                         if (!cppi_rx_scan(cppi, index))
1268                                 continue;
1269 
1270                         /* start another dma segment if needed */
1271                         if (rx_ch->channel.actual_len != rx_ch->buf_len
1272                                         && rx_ch->channel.actual_len
1273                                                 == rx_ch->offset) {
1274                                 cppi_next_rx_segment(musb, rx_ch, 1);
1275                                 continue;
1276                         }
1277 
1278                         /* all segments completed! */
1279                         rx_ch->channel.status = MUSB_DMA_STATUS_FREE;
1280 
1281                         hw_ep = rx_ch->hw_ep;
1282 
1283                         core_rxirq_disable(tibase, index + 1);
1284                         musb_dma_completion(musb, index + 1, 0);
1285                 }
1286         }
1287 
1288         /* write to CPPI EOI register to re-enable interrupts */
1289         musb_writel(tibase, DAVINCI_CPPI_EOI_REG, 0);
1290 
1291         if (cppi->irq)
1292                 spin_unlock_irqrestore(&musb->lock, flags);
1293 
1294         return IRQ_HANDLED;
1295 }
1296 EXPORT_SYMBOL_GPL(cppi_interrupt);
1297 
1298 /* Instantiate a software object representing a DMA controller. */
1299 struct dma_controller *
1300 cppi_dma_controller_create(struct musb *musb, void __iomem *mregs)
1301 {
1302         struct cppi             *controller;
1303         struct device           *dev = musb->controller;
1304         struct platform_device  *pdev = to_platform_device(dev);
1305         int                     irq = platform_get_irq_byname(pdev, "dma");
1306 
1307         controller = kzalloc(sizeof *controller, GFP_KERNEL);
1308         if (!controller)
1309                 return NULL;
1310 
1311         controller->mregs = mregs;
1312         controller->tibase = mregs - DAVINCI_BASE_OFFSET;
1313 
1314         controller->controller.musb = musb;
1315         controller->controller.channel_alloc = cppi_channel_allocate;
1316         controller->controller.channel_release = cppi_channel_release;
1317         controller->controller.channel_program = cppi_channel_program;
1318         controller->controller.channel_abort = cppi_channel_abort;
1319 
1320         /* NOTE: allocating from on-chip SRAM would give the least
1321          * contention for memory access, if that ever matters here.
1322          */
1323 
1324         /* setup BufferPool */
1325         controller->pool = dma_pool_create("cppi",
1326                         controller->controller.musb->controller,
1327                         sizeof(struct cppi_descriptor),
1328                         CPPI_DESCRIPTOR_ALIGN, 0);
1329         if (!controller->pool) {
1330                 kfree(controller);
1331                 return NULL;
1332         }
1333 
1334         if (irq > 0) {
1335                 if (request_irq(irq, cppi_interrupt, 0, "cppi-dma", musb)) {
1336                         dev_err(dev, "request_irq %d failed!\n", irq);
1337                         musb_dma_controller_destroy(&controller->controller);
1338                         return NULL;
1339                 }
1340                 controller->irq = irq;
1341         }
1342 
1343         cppi_controller_start(controller);
1344         return &controller->controller;
1345 }
1346 EXPORT_SYMBOL_GPL(cppi_dma_controller_create);
1347 
1348 /*
1349  *  Destroy a previously-instantiated DMA controller.
1350  */
1351 void cppi_dma_controller_destroy(struct dma_controller *c)
1352 {
1353         struct cppi     *cppi;
1354 
1355         cppi = container_of(c, struct cppi, controller);
1356 
1357         cppi_controller_stop(cppi);
1358 
1359         if (cppi->irq)
1360                 free_irq(cppi->irq, cppi->controller.musb);
1361 
1362         /* assert:  caller stopped the controller first */
1363         dma_pool_destroy(cppi->pool);
1364 
1365         kfree(cppi);
1366 }
1367 EXPORT_SYMBOL_GPL(cppi_dma_controller_destroy);
1368 
1369 /*
1370  * Context: controller irqlocked, endpoint selected
1371  */
1372 static int cppi_channel_abort(struct dma_channel *channel)
1373 {
1374         struct cppi_channel     *cppi_ch;
1375         struct cppi             *controller;
1376         void __iomem            *mbase;
1377         void __iomem            *tibase;
1378         void __iomem            *regs;
1379         u32                     value;
1380         struct cppi_descriptor  *queue;
1381 
1382         cppi_ch = container_of(channel, struct cppi_channel, channel);
1383 
1384         controller = cppi_ch->controller;
1385 
1386         switch (channel->status) {
1387         case MUSB_DMA_STATUS_BUS_ABORT:
1388         case MUSB_DMA_STATUS_CORE_ABORT:
1389                 /* from RX or TX fault irq handler */
1390         case MUSB_DMA_STATUS_BUSY:
1391                 /* the hardware needs shutting down */
1392                 regs = cppi_ch->hw_ep->regs;
1393                 break;
1394         case MUSB_DMA_STATUS_UNKNOWN:
1395         case MUSB_DMA_STATUS_FREE:
1396                 return 0;
1397         default:
1398                 return -EINVAL;
1399         }
1400 
1401         if (!cppi_ch->transmit && cppi_ch->head)
1402                 cppi_dump_rxq(3, "/abort", cppi_ch);
1403 
1404         mbase = controller->mregs;
1405         tibase = controller->tibase;
1406 
1407         queue = cppi_ch->head;
1408         cppi_ch->head = NULL;
1409         cppi_ch->tail = NULL;
1410 
1411         /* REVISIT should rely on caller having done this,
1412          * and caller should rely on us not changing it.
1413          * peripheral code is safe ... check host too.
1414          */
1415         musb_ep_select(mbase, cppi_ch->index + 1);
1416 
1417         if (cppi_ch->transmit) {
1418                 struct cppi_tx_stateram __iomem *tx_ram;
1419                 /* REVISIT put timeouts on these controller handshakes */
1420 
1421                 cppi_dump_tx(6, cppi_ch, " (teardown)");
1422 
1423                 /* teardown DMA engine then usb core */
1424                 do {
1425                         value = musb_readl(tibase, DAVINCI_TXCPPI_TEAR_REG);
1426                 } while (!(value & CPPI_TEAR_READY));
1427                 musb_writel(tibase, DAVINCI_TXCPPI_TEAR_REG, cppi_ch->index);
1428 
1429                 tx_ram = cppi_ch->state_ram;
1430                 do {
1431                         value = musb_readl(&tx_ram->tx_complete, 0);
1432                 } while (0xFFFFFFFC != value);
1433 
1434                 /* FIXME clean up the transfer state ... here?
1435                  * the completion routine should get called with
1436                  * an appropriate status code.
1437                  */
1438 
1439                 value = musb_readw(regs, MUSB_TXCSR);
1440                 value &= ~MUSB_TXCSR_DMAENAB;
1441                 value |= MUSB_TXCSR_FLUSHFIFO;
1442                 musb_writew(regs, MUSB_TXCSR, value);
1443                 musb_writew(regs, MUSB_TXCSR, value);
1444 
1445                 /*
1446                  * 1. Write to completion Ptr value 0x1(bit 0 set)
1447                  *    (write back mode)
1448                  * 2. Wait for abort interrupt and then put the channel in
1449                  *    compare mode by writing 1 to the tx_complete register.
1450                  */
1451                 cppi_reset_tx(tx_ram, 1);
1452                 cppi_ch->head = NULL;
1453                 musb_writel(&tx_ram->tx_complete, 0, 1);
1454                 cppi_dump_tx(5, cppi_ch, " (done teardown)");
1455 
1456                 /* REVISIT tx side _should_ clean up the same way
1457                  * as the RX side ... this does no cleanup at all!
1458                  */
1459 
1460         } else /* RX */ {
1461                 u16                     csr;
1462 
1463                 /* NOTE: docs don't guarantee any of this works ...  we
1464                  * expect that if the usb core stops telling the cppi core
1465                  * to pull more data from it, then it'll be safe to flush
1466                  * current RX DMA state iff any pending fifo transfer is done.
1467                  */
1468 
1469                 core_rxirq_disable(tibase, cppi_ch->index + 1);
1470 
1471                 /* for host, ensure ReqPkt is never set again */
1472                 if (is_host_active(cppi_ch->controller->controller.musb)) {
1473                         value = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
1474                         value &= ~((0x3) << (cppi_ch->index * 2));
1475                         musb_writel(tibase, DAVINCI_AUTOREQ_REG, value);
1476                 }
1477 
1478                 csr = musb_readw(regs, MUSB_RXCSR);
1479 
1480                 /* for host, clear (just) ReqPkt at end of current packet(s) */
1481                 if (is_host_active(cppi_ch->controller->controller.musb)) {
1482                         csr |= MUSB_RXCSR_H_WZC_BITS;
1483                         csr &= ~MUSB_RXCSR_H_REQPKT;
1484                 } else
1485                         csr |= MUSB_RXCSR_P_WZC_BITS;
1486 
1487                 /* clear dma enable */
1488                 csr &= ~(MUSB_RXCSR_DMAENAB);
1489                 musb_writew(regs, MUSB_RXCSR, csr);
1490                 csr = musb_readw(regs, MUSB_RXCSR);
1491 
1492                 /* Quiesce: wait for current dma to finish (if not cleanup).
1493                  * We can't use bit zero of stateram->rx_sop, since that
1494                  * refers to an entire "DMA packet" not just emptying the
1495                  * current fifo.  Most segments need multiple usb packets.
1496                  */
1497                 if (channel->status == MUSB_DMA_STATUS_BUSY)
1498                         udelay(50);
1499 
1500                 /* scan the current list, reporting any data that was
1501                  * transferred and acking any IRQ
1502                  */
1503                 cppi_rx_scan(controller, cppi_ch->index);
1504 
1505                 /* clobber the existing state once it's idle
1506                  *
1507                  * NOTE:  arguably, we should also wait for all the other
1508                  * RX channels to quiesce (how??) and then temporarily
1509                  * disable RXCPPI_CTRL_REG ... but it seems that we can
1510                  * rely on the controller restarting from state ram, with
1511                  * only RXCPPI_BUFCNT state being bogus.  BUFCNT will
1512                  * correct itself after the next DMA transfer though.
1513                  *
1514                  * REVISIT does using rndis mode change that?
1515                  */
1516                 cppi_reset_rx(cppi_ch->state_ram);
1517 
1518                 /* next DMA request _should_ load cppi head ptr */
1519 
1520                 /* ... we don't "free" that list, only mutate it in place.  */
1521                 cppi_dump_rx(5, cppi_ch, " (done abort)");
1522 
1523                 /* clean up previously pending bds */
1524                 cppi_bd_free(cppi_ch, cppi_ch->last_processed);
1525                 cppi_ch->last_processed = NULL;
1526 
1527                 while (queue) {
1528                         struct cppi_descriptor  *tmp = queue->next;
1529 
1530                         cppi_bd_free(cppi_ch, queue);
1531                         queue = tmp;
1532                 }
1533         }
1534 
1535         channel->status = MUSB_DMA_STATUS_FREE;
1536         cppi_ch->buf_dma = 0;
1537         cppi_ch->offset = 0;
1538         cppi_ch->buf_len = 0;
1539         cppi_ch->maxpacket = 0;
1540         return 0;
1541 }
1542 
1543 /* TBD Queries:
1544  *
1545  * Power Management ... probably turn off cppi during suspend, restart;
1546  * check state ram?  Clocking is presumably shared with usb core.
1547  */

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