--- /dev/null
+/*
+ * Copyright (C) 2005-2006 by Texas Instruments
+ *
+ * This file implements a DMA interface using TI's CPPI DMA.
+ * For now it's DaVinci-only, but CPPI isn't specific to DaVinci or USB.
+ * The TUSB6020, using VLYNQ, has CPPI that looks much like DaVinci.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include "musb_core.h"
+#include "musb_debug.h"
+#include "cppi_dma.h"
+
+
+/* CPPI DMA status 7-mar-2006:
+ *
+ * - See musb_{host,gadget}.c for more info
+ *
+ * - Correct RX DMA generally forces the engine into irq-per-packet mode,
+ * which can easily saturate the CPU under non-mass-storage loads.
+ *
+ * NOTES 24-aug-2006 (2.6.18-rc4):
+ *
+ * - peripheral RXDMA wedged in a test with packets of length 512/512/1.
+ * evidently after the 1 byte packet was received and acked, the queue
+ * of BDs got garbaged so it wouldn't empty the fifo. (rxcsr 0x2003,
+ * and RX DMA0: 4 left, 80000000 8feff880, 8feff860 8feff860; 8f321401
+ * 004001ff 00000001 .. 8feff860) Host was just getting NAKed on tx
+ * of its next (512 byte) packet. IRQ issues?
+ *
+ * REVISIT: the "transfer DMA" glue between CPPI and USB fifos will
+ * evidently also directly update the RX and TX CSRs ... so audit all
+ * host and peripheral side DMA code to avoid CSR access after DMA has
+ * been started.
+ */
+
+/* REVISIT now we can avoid preallocating these descriptors; or
+ * more simply, switch to a global freelist not per-channel ones.
+ * Note: at full speed, 64 descriptors == 4K bulk data.
+ */
+#define NUM_TXCHAN_BD 64
+#define NUM_RXCHAN_BD 64
+
+static inline void cpu_drain_writebuffer(void)
+{
+ wmb();
+#ifdef CONFIG_CPU_ARM926T
+ /* REVISIT this "should not be needed",
+ * but lack of it sure seemed to hurt ...
+ */
+ asm("mcr p15, 0, r0, c7, c10, 4 @ drain write buffer\n");
+#endif
+}
+
+static inline struct cppi_descriptor *cppi_bd_alloc(struct cppi_channel *c)
+{
+ struct cppi_descriptor *bd = c->freelist;
+
+ if (bd)
+ c->freelist = bd->next;
+ return bd;
+}
+
+static inline void
+cppi_bd_free(struct cppi_channel *c, struct cppi_descriptor *bd)
+{
+ if (!bd)
+ return;
+ bd->next = c->freelist;
+ c->freelist = bd;
+}
+
+/*
+ * Start DMA controller
+ *
+ * Initialize the DMA controller as necessary.
+ */
+
+/* zero out entire rx state RAM entry for the channel */
+static void cppi_reset_rx(struct cppi_rx_stateram __iomem *rx)
+{
+ musb_writel(&rx->rx_skipbytes, 0, 0);
+ musb_writel(&rx->rx_head, 0, 0);
+ musb_writel(&rx->rx_sop, 0, 0);
+ musb_writel(&rx->rx_current, 0, 0);
+ musb_writel(&rx->rx_buf_current, 0, 0);
+ musb_writel(&rx->rx_len_len, 0, 0);
+ musb_writel(&rx->rx_cnt_cnt, 0, 0);
+}
+
+/* zero out entire tx state RAM entry for the channel */
+static void cppi_reset_tx(struct cppi_tx_stateram __iomem *tx, u32 ptr)
+{
+ musb_writel(&tx->tx_head, 0, 0);
+ musb_writel(&tx->tx_buf, 0, 0);
+ musb_writel(&tx->tx_current, 0, 0);
+ musb_writel(&tx->tx_buf_current, 0, 0);
+ musb_writel(&tx->tx_info, 0, 0);
+ musb_writel(&tx->tx_rem_len, 0, 0);
+ /* musb_writel(&tx->tx_dummy, 0, 0); */
+ musb_writel(&tx->tx_complete, 0, ptr);
+}
+
+static void cppi_pool_init(struct cppi *cppi, struct cppi_channel *c)
+{
+ int j;
+
+ /* initialize channel fields */
+ c->head = NULL;
+ c->tail = NULL;
+ c->last_processed = NULL;
+ c->channel.status = MUSB_DMA_STATUS_UNKNOWN;
+ c->controller = cppi;
+ c->is_rndis = 0;
+ c->freelist = NULL;
+
+ /* build the BD Free list for the channel */
+ for (j = 0; j < NUM_TXCHAN_BD + 1; j++) {
+ struct cppi_descriptor *bd;
+ dma_addr_t dma;
+
+ bd = dma_pool_alloc(cppi->pool, GFP_KERNEL, &dma);
+ bd->dma = dma;
+ cppi_bd_free(c, bd);
+ }
+}
+
+static int cppi_channel_abort(struct dma_channel *);
+
+static void cppi_pool_free(struct cppi_channel *c)
+{
+ struct cppi *cppi = c->controller;
+ struct cppi_descriptor *bd;
+
+ (void) cppi_channel_abort(&c->channel);
+ c->channel.status = MUSB_DMA_STATUS_UNKNOWN;
+ c->controller = NULL;
+
+ /* free all its bds */
+ bd = c->last_processed;
+ do {
+ if (bd)
+ dma_pool_free(cppi->pool, bd, bd->dma);
+ bd = cppi_bd_alloc(c);
+ } while (bd);
+ c->last_processed = NULL;
+}
+
+static void cppi_controller_start(struct cppi *controller)
+{
+ void __iomem *tibase;
+ int i;
+
+ /* do whatever is necessary to start controller */
+ for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
+ controller->tx[i].transmit = true;
+ controller->tx[i].index = i;
+ }
+ for (i = 0; i < ARRAY_SIZE(controller->rx); i++) {
+ controller->rx[i].transmit = false;
+ controller->rx[i].index = i;
+ }
+
+ /* setup BD list on a per channel basis */
+ for (i = 0; i < ARRAY_SIZE(controller->tx); i++)
+ cppi_pool_init(controller, controller->tx + i);
+ for (i = 0; i < ARRAY_SIZE(controller->rx); i++)
+ cppi_pool_init(controller, controller->rx + i);
+
+ tibase = controller->tibase;
+ INIT_LIST_HEAD(&controller->tx_complete);
+
+ /* initialise tx/rx channel head pointers to zero */
+ for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
+ struct cppi_channel *tx_ch = controller->tx + i;
+ struct cppi_tx_stateram __iomem *tx;
+
+ INIT_LIST_HEAD(&tx_ch->tx_complete);
+
+ tx = tibase + DAVINCI_TXCPPI_STATERAM_OFFSET(i);
+ tx_ch->state_ram = tx;
+ cppi_reset_tx(tx, 0);
+ }
+ for (i = 0; i < ARRAY_SIZE(controller->rx); i++) {
+ struct cppi_channel *rx_ch = controller->rx + i;
+ struct cppi_rx_stateram __iomem *rx;
+
+ INIT_LIST_HEAD(&rx_ch->tx_complete);
+
+ rx = tibase + DAVINCI_RXCPPI_STATERAM_OFFSET(i);
+ rx_ch->state_ram = rx;
+ cppi_reset_rx(rx);
+ }
+
+ /* enable individual cppi channels */
+ musb_writel(tibase, DAVINCI_TXCPPI_INTENAB_REG,
+ DAVINCI_DMA_ALL_CHANNELS_ENABLE);
+ musb_writel(tibase, DAVINCI_RXCPPI_INTENAB_REG,
+ DAVINCI_DMA_ALL_CHANNELS_ENABLE);
+
+ /* enable tx/rx CPPI control */
+ musb_writel(tibase, DAVINCI_TXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_ENABLE);
+ musb_writel(tibase, DAVINCI_RXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_ENABLE);
+
+ /* disable RNDIS mode, also host rx RNDIS autorequest */
+ musb_writel(tibase, DAVINCI_RNDIS_REG, 0);
+ musb_writel(tibase, DAVINCI_AUTOREQ_REG, 0);
+}
+
+/*
+ * Stop DMA controller
+ *
+ * De-Init the DMA controller as necessary.
+ */
+
+static void cppi_controller_stop(struct cppi *controller)
+{
+ void __iomem *tibase;
+ int i;
+ struct musb *musb;
+
+ musb = controller->musb;
+
+ tibase = controller->tibase;
+ /* DISABLE INDIVIDUAL CHANNEL Interrupts */
+ musb_writel(tibase, DAVINCI_TXCPPI_INTCLR_REG,
+ DAVINCI_DMA_ALL_CHANNELS_ENABLE);
+ musb_writel(tibase, DAVINCI_RXCPPI_INTCLR_REG,
+ DAVINCI_DMA_ALL_CHANNELS_ENABLE);
+
+ dev_dbg(musb->controller, "Tearing down RX and TX Channels\n");
+ for (i = 0; i < ARRAY_SIZE(controller->tx); i++) {
+ /* FIXME restructure of txdma to use bds like rxdma */
+ controller->tx[i].last_processed = NULL;
+ cppi_pool_free(controller->tx + i);
+ }
+ for (i = 0; i < ARRAY_SIZE(controller->rx); i++)
+ cppi_pool_free(controller->rx + i);
+
+ /* in Tx Case proper teardown is supported. We resort to disabling
+ * Tx/Rx CPPI after cleanup of Tx channels. Before TX teardown is
+ * complete TX CPPI cannot be disabled.
+ */
+ /*disable tx/rx cppi */
+ musb_writel(tibase, DAVINCI_TXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_DISABLE);
+ musb_writel(tibase, DAVINCI_RXCPPI_CTRL_REG, DAVINCI_DMA_CTRL_DISABLE);
+}
+
+/* While dma channel is allocated, we only want the core irqs active
+ * for fault reports, otherwise we'd get irqs that we don't care about.
+ * Except for TX irqs, where dma done != fifo empty and reusable ...
+ *
+ * NOTE: docs don't say either way, but irq masking **enables** irqs.
+ *
+ * REVISIT same issue applies to pure PIO usage too, and non-cppi dma...
+ */
+static inline void core_rxirq_disable(void __iomem *tibase, unsigned epnum)
+{
+ musb_writel(tibase, DAVINCI_USB_INT_MASK_CLR_REG, 1 << (epnum + 8));
+}
+
+static inline void core_rxirq_enable(void __iomem *tibase, unsigned epnum)
+{
+ musb_writel(tibase, DAVINCI_USB_INT_MASK_SET_REG, 1 << (epnum + 8));
+}
+
+
+/*
+ * Allocate a CPPI Channel for DMA. With CPPI, channels are bound to
+ * each transfer direction of a non-control endpoint, so allocating
+ * (and deallocating) is mostly a way to notice bad housekeeping on
+ * the software side. We assume the irqs are always active.
+ */
+static struct dma_channel *
+cppi_channel_allocate(struct dma_controller *c,
+ struct musb_hw_ep *ep, u8 transmit)
+{
+ struct cppi *controller;
+ u8 index;
+ struct cppi_channel *cppi_ch;
+ void __iomem *tibase;
+ struct musb *musb;
+
+ controller = container_of(c, struct cppi, controller);
+ tibase = controller->tibase;
+ musb = controller->musb;
+
+ /* ep0 doesn't use DMA; remember cppi indices are 0..N-1 */
+ index = ep->epnum - 1;
+
+ /* return the corresponding CPPI Channel Handle, and
+ * probably disable the non-CPPI irq until we need it.
+ */
+ if (transmit) {
+ if (index >= ARRAY_SIZE(controller->tx)) {
+ dev_dbg(musb->controller, "no %cX%d CPPI channel\n", 'T', index);
+ return NULL;
+ }
+ cppi_ch = controller->tx + index;
+ } else {
+ if (index >= ARRAY_SIZE(controller->rx)) {
+ dev_dbg(musb->controller, "no %cX%d CPPI channel\n", 'R', index);
+ return NULL;
+ }
+ cppi_ch = controller->rx + index;
+ core_rxirq_disable(tibase, ep->epnum);
+ }
+
+ /* REVISIT make this an error later once the same driver code works
+ * with the other DMA engine too
+ */
+ if (cppi_ch->hw_ep)
+ dev_dbg(musb->controller, "re-allocating DMA%d %cX channel %p\n",
+ index, transmit ? 'T' : 'R', cppi_ch);
+ cppi_ch->hw_ep = ep;
+ cppi_ch->channel.status = MUSB_DMA_STATUS_FREE;
+ cppi_ch->channel.max_len = 0x7fffffff;
+
+ dev_dbg(musb->controller, "Allocate CPPI%d %cX\n", index, transmit ? 'T' : 'R');
+ return &cppi_ch->channel;
+}
+
+/* Release a CPPI Channel. */
+static void cppi_channel_release(struct dma_channel *channel)
+{
+ struct cppi_channel *c;
+ void __iomem *tibase;
+
+ /* REVISIT: for paranoia, check state and abort if needed... */
+
+ c = container_of(channel, struct cppi_channel, channel);
+ tibase = c->controller->tibase;
+ if (!c->hw_ep)
+ dev_dbg(c->controller->musb->controller,
+ "releasing idle DMA channel %p\n", c);
+ else if (!c->transmit)
+ core_rxirq_enable(tibase, c->index + 1);
+
+ /* for now, leave its cppi IRQ enabled (we won't trigger it) */
+ c->hw_ep = NULL;
+ channel->status = MUSB_DMA_STATUS_UNKNOWN;
+}
+
+/* Context: controller irqlocked */
+static void
+cppi_dump_rx(int level, struct cppi_channel *c, const char *tag)
+{
+ void __iomem *base = c->controller->mregs;
+ struct cppi_rx_stateram __iomem *rx = c->state_ram;
+
+ musb_ep_select(base, c->index + 1);
+
+ dev_dbg(c->controller->musb->controller,
+ "RX DMA%d%s: %d left, csr %04x, "
+ "%08x H%08x S%08x C%08x, "
+ "B%08x L%08x %08x .. %08x"
+ "\n",
+ c->index, tag,
+ musb_readl(c->controller->tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + 4 * c->index),
+ musb_readw(c->hw_ep->regs, MUSB_RXCSR),
+
+ musb_readl(&rx->rx_skipbytes, 0),
+ musb_readl(&rx->rx_head, 0),
+ musb_readl(&rx->rx_sop, 0),
+ musb_readl(&rx->rx_current, 0),
+
+ musb_readl(&rx->rx_buf_current, 0),
+ musb_readl(&rx->rx_len_len, 0),
+ musb_readl(&rx->rx_cnt_cnt, 0),
+ musb_readl(&rx->rx_complete, 0)
+ );
+}
+
+/* Context: controller irqlocked */
+static void
+cppi_dump_tx(int level, struct cppi_channel *c, const char *tag)
+{
+ void __iomem *base = c->controller->mregs;
+ struct cppi_tx_stateram __iomem *tx = c->state_ram;
+
+ musb_ep_select(base, c->index + 1);
+
+ dev_dbg(c->controller->musb->controller,
+ "TX DMA%d%s: csr %04x, "
+ "H%08x S%08x C%08x %08x, "
+ "F%08x L%08x .. %08x"
+ "\n",
+ c->index, tag,
+ musb_readw(c->hw_ep->regs, MUSB_TXCSR),
+
+ musb_readl(&tx->tx_head, 0),
+ musb_readl(&tx->tx_buf, 0),
+ musb_readl(&tx->tx_current, 0),
+ musb_readl(&tx->tx_buf_current, 0),
+
+ musb_readl(&tx->tx_info, 0),
+ musb_readl(&tx->tx_rem_len, 0),
+ /* dummy/unused word 6 */
+ musb_readl(&tx->tx_complete, 0)
+ );
+}
+
+/* Context: controller irqlocked */
+static inline void
+cppi_rndis_update(struct cppi_channel *c, int is_rx,
+ void __iomem *tibase, int is_rndis)
+{
+ /* we may need to change the rndis flag for this cppi channel */
+ if (c->is_rndis != is_rndis) {
+ u32 value = musb_readl(tibase, DAVINCI_RNDIS_REG);
+ u32 temp = 1 << (c->index);
+
+ if (is_rx)
+ temp <<= 16;
+ if (is_rndis)
+ value |= temp;
+ else
+ value &= ~temp;
+ musb_writel(tibase, DAVINCI_RNDIS_REG, value);
+ c->is_rndis = is_rndis;
+ }
+}
+
+static void cppi_dump_rxbd(const char *tag, struct cppi_descriptor *bd)
+{
+ pr_debug("RXBD/%s %08x: "
+ "nxt %08x buf %08x off.blen %08x opt.plen %08x\n",
+ tag, bd->dma,
+ bd->hw_next, bd->hw_bufp, bd->hw_off_len,
+ bd->hw_options);
+}
+
+static void cppi_dump_rxq(int level, const char *tag, struct cppi_channel *rx)
+{
+ struct cppi_descriptor *bd;
+
+ cppi_dump_rx(level, rx, tag);
+ if (rx->last_processed)
+ cppi_dump_rxbd("last", rx->last_processed);
+ for (bd = rx->head; bd; bd = bd->next)
+ cppi_dump_rxbd("active", bd);
+}
+
+
+/* NOTE: DaVinci autoreq is ignored except for host side "RNDIS" mode RX;
+ * so we won't ever use it (see "CPPI RX Woes" below).
+ */
+static inline int cppi_autoreq_update(struct cppi_channel *rx,
+ void __iomem *tibase, int onepacket, unsigned n_bds)
+{
+ u32 val;
+
+#ifdef RNDIS_RX_IS_USABLE
+ u32 tmp;
+ /* assert(is_host_active(musb)) */
+
+ /* start from "AutoReq never" */
+ tmp = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
+ val = tmp & ~((0x3) << (rx->index * 2));
+
+ /* HCD arranged reqpkt for packet #1. we arrange int
+ * for all but the last one, maybe in two segments.
+ */
+ if (!onepacket) {
+#if 0
+ /* use two segments, autoreq "all" then the last "never" */
+ val |= ((0x3) << (rx->index * 2));
+ n_bds--;
+#else
+ /* one segment, autoreq "all-but-last" */
+ val |= ((0x1) << (rx->index * 2));
+#endif
+ }
+
+ if (val != tmp) {
+ int n = 100;
+
+ /* make sure that autoreq is updated before continuing */
+ musb_writel(tibase, DAVINCI_AUTOREQ_REG, val);
+ do {
+ tmp = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
+ if (tmp == val)
+ break;
+ cpu_relax();
+ } while (n-- > 0);
+ }
+#endif
+
+ /* REQPKT is turned off after each segment */
+ if (n_bds && rx->channel.actual_len) {
+ void __iomem *regs = rx->hw_ep->regs;
+
+ val = musb_readw(regs, MUSB_RXCSR);
+ if (!(val & MUSB_RXCSR_H_REQPKT)) {
+ val |= MUSB_RXCSR_H_REQPKT | MUSB_RXCSR_H_WZC_BITS;
+ musb_writew(regs, MUSB_RXCSR, val);
+ /* flush writebuffer */
+ val = musb_readw(regs, MUSB_RXCSR);
+ }
+ }
+ return n_bds;
+}
+
+
+/* Buffer enqueuing Logic:
+ *
+ * - RX builds new queues each time, to help handle routine "early
+ * termination" cases (faults, including errors and short reads)
+ * more correctly.
+ *
+ * - for now, TX reuses the same queue of BDs every time
+ *
+ * REVISIT long term, we want a normal dynamic model.
+ * ... the goal will be to append to the
+ * existing queue, processing completed "dma buffers" (segments) on the fly.
+ *
+ * Otherwise we force an IRQ latency between requests, which slows us a lot
+ * (especially in "transparent" dma). Unfortunately that model seems to be
+ * inherent in the DMA model from the Mentor code, except in the rare case
+ * of transfers big enough (~128+ KB) that we could append "middle" segments
+ * in the TX paths. (RX can't do this, see below.)
+ *
+ * That's true even in the CPPI- friendly iso case, where most urbs have
+ * several small segments provided in a group and where the "packet at a time"
+ * "transparent" DMA model is always correct, even on the RX side.
+ */
+
+/*
+ * CPPI TX:
+ * ========
+ * TX is a lot more reasonable than RX; it doesn't need to run in
+ * irq-per-packet mode very often. RNDIS mode seems to behave too
+ * (except how it handles the exactly-N-packets case). Building a
+ * txdma queue with multiple requests (urb or usb_request) looks
+ * like it would work ... but fault handling would need much testing.
+ *
+ * The main issue with TX mode RNDIS relates to transfer lengths that
+ * are an exact multiple of the packet length. It appears that there's
+ * a hiccup in that case (maybe the DMA completes before the ZLP gets
+ * written?) boiling down to not being able to rely on CPPI writing any
+ * terminating zero length packet before the next transfer is written.
+ * So that's punted to PIO; better yet, gadget drivers can avoid it.
+ *
+ * Plus, there's allegedly an undocumented constraint that rndis transfer
+ * length be a multiple of 64 bytes ... but the chip doesn't act that
+ * way, and we really don't _want_ that behavior anyway.
+ *
+ * On TX, "transparent" mode works ... although experiments have shown
+ * problems trying to use the SOP/EOP bits in different USB packets.
+ *
+ * REVISIT try to handle terminating zero length packets using CPPI
+ * instead of doing it by PIO after an IRQ. (Meanwhile, make Ethernet
+ * links avoid that issue by forcing them to avoid zlps.)
+ */
+static void
+cppi_next_tx_segment(struct musb *musb, struct cppi_channel *tx)
+{
+ unsigned maxpacket = tx->maxpacket;
+ dma_addr_t addr = tx->buf_dma + tx->offset;
+ size_t length = tx->buf_len - tx->offset;
+ struct cppi_descriptor *bd;
+ unsigned n_bds;
+ unsigned i;
+ struct cppi_tx_stateram __iomem *tx_ram = tx->state_ram;
+ int rndis;
+
+ /* TX can use the CPPI "rndis" mode, where we can probably fit this
+ * transfer in one BD and one IRQ. The only time we would NOT want
+ * to use it is when hardware constraints prevent it, or if we'd
+ * trigger the "send a ZLP?" confusion.
+ */
+ rndis = (maxpacket & 0x3f) == 0
+ && length > maxpacket
+ && length < 0xffff
+ && (length % maxpacket) != 0;
+
+ if (rndis) {
+ maxpacket = length;
+ n_bds = 1;
+ } else {
+ n_bds = length / maxpacket;
+ if (!length || (length % maxpacket))
+ n_bds++;
+ n_bds = min(n_bds, (unsigned) NUM_TXCHAN_BD);
+ length = min(n_bds * maxpacket, length);
+ }
+
+ dev_dbg(musb->controller, "TX DMA%d, pktSz %d %s bds %d dma 0x%llx len %u\n",
+ tx->index,
+ maxpacket,
+ rndis ? "rndis" : "transparent",
+ n_bds,
+ (unsigned long long)addr, length);
+
+ cppi_rndis_update(tx, 0, musb->ctrl_base, rndis);
+
+ /* assuming here that channel_program is called during
+ * transfer initiation ... current code maintains state
+ * for one outstanding request only (no queues, not even
+ * the implicit ones of an iso urb).
+ */
+
+ bd = tx->freelist;
+ tx->head = bd;
+ tx->last_processed = NULL;
+
+ /* FIXME use BD pool like RX side does, and just queue
+ * the minimum number for this request.
+ */
+
+ /* Prepare queue of BDs first, then hand it to hardware.
+ * All BDs except maybe the last should be of full packet
+ * size; for RNDIS there _is_ only that last packet.
+ */
+ for (i = 0; i < n_bds; ) {
+ if (++i < n_bds && bd->next)
+ bd->hw_next = bd->next->dma;
+ else
+ bd->hw_next = 0;
+
+ bd->hw_bufp = tx->buf_dma + tx->offset;
+
+ /* FIXME set EOP only on the last packet,
+ * SOP only on the first ... avoid IRQs
+ */
+ if ((tx->offset + maxpacket) <= tx->buf_len) {
+ tx->offset += maxpacket;
+ bd->hw_off_len = maxpacket;
+ bd->hw_options = CPPI_SOP_SET | CPPI_EOP_SET
+ | CPPI_OWN_SET | maxpacket;
+ } else {
+ /* only this one may be a partial USB Packet */
+ u32 partial_len;
+
+ partial_len = tx->buf_len - tx->offset;
+ tx->offset = tx->buf_len;
+ bd->hw_off_len = partial_len;
+
+ bd->hw_options = CPPI_SOP_SET | CPPI_EOP_SET
+ | CPPI_OWN_SET | partial_len;
+ if (partial_len == 0)
+ bd->hw_options |= CPPI_ZERO_SET;
+ }
+
+ dev_dbg(musb->controller, "TXBD %p: nxt %08x buf %08x len %04x opt %08x\n",
+ bd, bd->hw_next, bd->hw_bufp,
+ bd->hw_off_len, bd->hw_options);
+
+ /* update the last BD enqueued to the list */
+ tx->tail = bd;
+ bd = bd->next;
+ }
+
+ /* BDs live in DMA-coherent memory, but writes might be pending */
+ cpu_drain_writebuffer();
+
+ /* Write to the HeadPtr in state RAM to trigger */
+ musb_writel(&tx_ram->tx_head, 0, (u32)tx->freelist->dma);
+
+ cppi_dump_tx(5, tx, "/S");
+}
+
+/*
+ * CPPI RX Woes:
+ * =============
+ * Consider a 1KB bulk RX buffer in two scenarios: (a) it's fed two 300 byte
+ * packets back-to-back, and (b) it's fed two 512 byte packets back-to-back.
+ * (Full speed transfers have similar scenarios.)
+ *
+ * The correct behavior for Linux is that (a) fills the buffer with 300 bytes,
+ * and the next packet goes into a buffer that's queued later; while (b) fills
+ * the buffer with 1024 bytes. How to do that with CPPI?
+ *
+ * - RX queues in "rndis" mode -- one single BD -- handle (a) correctly, but
+ * (b) loses **BADLY** because nothing (!) happens when that second packet
+ * fills the buffer, much less when a third one arrives. (Which makes this
+ * not a "true" RNDIS mode. In the RNDIS protocol short-packet termination
+ * is optional, and it's fine if peripherals -- not hosts! -- pad messages
+ * out to end-of-buffer. Standard PCI host controller DMA descriptors
+ * implement that mode by default ... which is no accident.)
+ *
+ * - RX queues in "transparent" mode -- two BDs with 512 bytes each -- have
+ * converse problems: (b) is handled right, but (a) loses badly. CPPI RX
+ * ignores SOP/EOP markings and processes both of those BDs; so both packets
+ * are loaded into the buffer (with a 212 byte gap between them), and the next
+ * buffer queued will NOT get its 300 bytes of data. (It seems like SOP/EOP
+ * are intended as outputs for RX queues, not inputs...)
+ *
+ * - A variant of "transparent" mode -- one BD at a time -- is the only way to
+ * reliably make both cases work, with software handling both cases correctly
+ * and at the significant penalty of needing an IRQ per packet. (The lack of
+ * I/O overlap can be slightly ameliorated by enabling double buffering.)
+ *
+ * So how to get rid of IRQ-per-packet? The transparent multi-BD case could
+ * be used in special cases like mass storage, which sets URB_SHORT_NOT_OK
+ * (or maybe its peripheral side counterpart) to flag (a) scenarios as errors
+ * with guaranteed driver level fault recovery and scrubbing out what's left
+ * of that garbaged datastream.
+ *
+ * But there seems to be no way to identify the cases where CPPI RNDIS mode
+ * is appropriate -- which do NOT include RNDIS host drivers, but do include
+ * the CDC Ethernet driver! -- and the documentation is incomplete/wrong.
+ * So we can't _ever_ use RX RNDIS mode ... except by using a heuristic
+ * that applies best on the peripheral side (and which could fail rudely).
+ *
+ * Leaving only "transparent" mode; we avoid multi-bd modes in almost all
+ * cases other than mass storage class. Otherwise we're correct but slow,
+ * since CPPI penalizes our need for a "true RNDIS" default mode.
+ */
+
+
+/* Heuristic, intended to kick in for ethernet/rndis peripheral ONLY
+ *
+ * IFF
+ * (a) peripheral mode ... since rndis peripherals could pad their
+ * writes to hosts, causing i/o failure; or we'd have to cope with
+ * a largely unknowable variety of host side protocol variants
+ * (b) and short reads are NOT errors ... since full reads would
+ * cause those same i/o failures
+ * (c) and read length is
+ * - less than 64KB (max per cppi descriptor)
+ * - not a multiple of 4096 (g_zero default, full reads typical)
+ * - N (>1) packets long, ditto (full reads not EXPECTED)
+ * THEN
+ * try rx rndis mode
+ *
+ * Cost of heuristic failing: RXDMA wedges at the end of transfers that
+ * fill out the whole buffer. Buggy host side usb network drivers could
+ * trigger that, but "in the field" such bugs seem to be all but unknown.
+ *
+ * So this module parameter lets the heuristic be disabled. When using
+ * gadgetfs, the heuristic will probably need to be disabled.
+ */
+static bool cppi_rx_rndis = 1;
+
+module_param(cppi_rx_rndis, bool, 0);
+MODULE_PARM_DESC(cppi_rx_rndis, "enable/disable RX RNDIS heuristic");
+
+
+/**
+ * cppi_next_rx_segment - dma read for the next chunk of a buffer
+ * @musb: the controller
+ * @rx: dma channel
+ * @onepacket: true unless caller treats short reads as errors, and
+ * performs fault recovery above usbcore.
+ * Context: controller irqlocked
+ *
+ * See above notes about why we can't use multi-BD RX queues except in
+ * rare cases (mass storage class), and can never use the hardware "rndis"
+ * mode (since it's not a "true" RNDIS mode) with complete safety..
+ *
+ * It's ESSENTIAL that callers specify "onepacket" mode unless they kick in
+ * code to recover from corrupted datastreams after each short transfer.
+ */
+static void
+cppi_next_rx_segment(struct musb *musb, struct cppi_channel *rx, int onepacket)
+{
+ unsigned maxpacket = rx->maxpacket;
+ dma_addr_t addr = rx->buf_dma + rx->offset;
+ size_t length = rx->buf_len - rx->offset;
+ struct cppi_descriptor *bd, *tail;
+ unsigned n_bds;
+ unsigned i;
+ void __iomem *tibase = musb->ctrl_base;
+ int is_rndis = 0;
+ struct cppi_rx_stateram __iomem *rx_ram = rx->state_ram;
+ struct cppi_descriptor *d;
+
+ if (onepacket) {
+ /* almost every USB driver, host or peripheral side */
+ n_bds = 1;
+
+ /* maybe apply the heuristic above */
+ if (cppi_rx_rndis
+ && is_peripheral_active(musb)
+ && length > maxpacket
+ && (length & ~0xffff) == 0
+ && (length & 0x0fff) != 0
+ && (length & (maxpacket - 1)) == 0) {
+ maxpacket = length;
+ is_rndis = 1;
+ }
+ } else {
+ /* virtually nothing except mass storage class */
+ if (length > 0xffff) {
+ n_bds = 0xffff / maxpacket;
+ length = n_bds * maxpacket;
+ } else {
+ n_bds = length / maxpacket;
+ if (length % maxpacket)
+ n_bds++;
+ }
+ if (n_bds == 1)
+ onepacket = 1;
+ else
+ n_bds = min(n_bds, (unsigned) NUM_RXCHAN_BD);
+ }
+
+ /* In host mode, autorequest logic can generate some IN tokens; it's
+ * tricky since we can't leave REQPKT set in RXCSR after the transfer
+ * finishes. So: multipacket transfers involve two or more segments.
+ * And always at least two IRQs ... RNDIS mode is not an option.
+ */
+ if (is_host_active(musb))
+ n_bds = cppi_autoreq_update(rx, tibase, onepacket, n_bds);
+
+ cppi_rndis_update(rx, 1, musb->ctrl_base, is_rndis);
+
+ length = min(n_bds * maxpacket, length);
+
+ dev_dbg(musb->controller, "RX DMA%d seg, maxp %d %s bds %d (cnt %d) "
+ "dma 0x%llx len %u %u/%u\n",
+ rx->index, maxpacket,
+ onepacket
+ ? (is_rndis ? "rndis" : "onepacket")
+ : "multipacket",
+ n_bds,
+ musb_readl(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
+ & 0xffff,
+ (unsigned long long)addr, length,
+ rx->channel.actual_len, rx->buf_len);
+
+ /* only queue one segment at a time, since the hardware prevents
+ * correct queue shutdown after unexpected short packets
+ */
+ bd = cppi_bd_alloc(rx);
+ rx->head = bd;
+
+ /* Build BDs for all packets in this segment */
+ for (i = 0, tail = NULL; bd && i < n_bds; i++, tail = bd) {
+ u32 bd_len;
+
+ if (i) {
+ bd = cppi_bd_alloc(rx);
+ if (!bd)
+ break;
+ tail->next = bd;
+ tail->hw_next = bd->dma;
+ }
+ bd->hw_next = 0;
+
+ /* all but the last packet will be maxpacket size */
+ if (maxpacket < length)
+ bd_len = maxpacket;
+ else
+ bd_len = length;
+
+ bd->hw_bufp = addr;
+ addr += bd_len;
+ rx->offset += bd_len;
+
+ bd->hw_off_len = (0 /*offset*/ << 16) + bd_len;
+ bd->buflen = bd_len;
+
+ bd->hw_options = CPPI_OWN_SET | (i == 0 ? length : 0);
+ length -= bd_len;
+ }
+
+ /* we always expect at least one reusable BD! */
+ if (!tail) {
+ WARNING("rx dma%d -- no BDs? need %d\n", rx->index, n_bds);
+ return;
+ } else if (i < n_bds)
+ WARNING("rx dma%d -- only %d of %d BDs\n", rx->index, i, n_bds);
+
+ tail->next = NULL;
+ tail->hw_next = 0;
+
+ bd = rx->head;
+ rx->tail = tail;
+
+ /* short reads and other faults should terminate this entire
+ * dma segment. we want one "dma packet" per dma segment, not
+ * one per USB packet, terminating the whole queue at once...
+ * NOTE that current hardware seems to ignore SOP and EOP.
+ */
+ bd->hw_options |= CPPI_SOP_SET;
+ tail->hw_options |= CPPI_EOP_SET;
+
+ for (d = rx->head; d; d = d->next)
+ cppi_dump_rxbd("S", d);
+
+ /* in case the preceding transfer left some state... */
+ tail = rx->last_processed;
+ if (tail) {
+ tail->next = bd;
+ tail->hw_next = bd->dma;
+ }
+
+ core_rxirq_enable(tibase, rx->index + 1);
+
+ /* BDs live in DMA-coherent memory, but writes might be pending */
+ cpu_drain_writebuffer();
+
+ /* REVISIT specs say to write this AFTER the BUFCNT register
+ * below ... but that loses badly.
+ */
+ musb_writel(&rx_ram->rx_head, 0, bd->dma);
+
+ /* bufferCount must be at least 3, and zeroes on completion
+ * unless it underflows below zero, or stops at two, or keeps
+ * growing ... grr.
+ */
+ i = musb_readl(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
+ & 0xffff;
+
+ if (!i)
+ musb_writel(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
+ n_bds + 2);
+ else if (n_bds > (i - 3))
+ musb_writel(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
+ n_bds - (i - 3));
+
+ i = musb_readl(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4))
+ & 0xffff;
+ if (i < (2 + n_bds)) {
+ dev_dbg(musb->controller, "bufcnt%d underrun - %d (for %d)\n",
+ rx->index, i, n_bds);
+ musb_writel(tibase,
+ DAVINCI_RXCPPI_BUFCNT0_REG + (rx->index * 4),
+ n_bds + 2);
+ }
+
+ cppi_dump_rx(4, rx, "/S");
+}
+
+/**
+ * cppi_channel_program - program channel for data transfer
+ * @ch: the channel
+ * @maxpacket: max packet size
+ * @mode: For RX, 1 unless the usb protocol driver promised to treat
+ * all short reads as errors and kick in high level fault recovery.
+ * For TX, ignored because of RNDIS mode races/glitches.
+ * @dma_addr: dma address of buffer
+ * @len: length of buffer
+ * Context: controller irqlocked
+ */
+static int cppi_channel_program(struct dma_channel *ch,
+ u16 maxpacket, u8 mode,
+ dma_addr_t dma_addr, u32 len)
+{
+ struct cppi_channel *cppi_ch;
+ struct cppi *controller;
+ struct musb *musb;
+
+ cppi_ch = container_of(ch, struct cppi_channel, channel);
+ controller = cppi_ch->controller;
+ musb = controller->musb;
+
+ switch (ch->status) {
+ case MUSB_DMA_STATUS_BUS_ABORT:
+ case MUSB_DMA_STATUS_CORE_ABORT:
+ /* fault irq handler should have handled cleanup */
+ WARNING("%cX DMA%d not cleaned up after abort!\n",
+ cppi_ch->transmit ? 'T' : 'R',
+ cppi_ch->index);
+ /* WARN_ON(1); */
+ break;
+ case MUSB_DMA_STATUS_BUSY:
+ WARNING("program active channel? %cX DMA%d\n",
+ cppi_ch->transmit ? 'T' : 'R',
+ cppi_ch->index);
+ /* WARN_ON(1); */
+ break;
+ case MUSB_DMA_STATUS_UNKNOWN:
+ dev_dbg(musb->controller, "%cX DMA%d not allocated!\n",
+ cppi_ch->transmit ? 'T' : 'R',
+ cppi_ch->index);
+ /* FALLTHROUGH */
+ case MUSB_DMA_STATUS_FREE:
+ break;
+ }
+
+ ch->status = MUSB_DMA_STATUS_BUSY;
+
+ /* set transfer parameters, then queue up its first segment */
+ cppi_ch->buf_dma = dma_addr;
+ cppi_ch->offset = 0;
+ cppi_ch->maxpacket = maxpacket;
+ cppi_ch->buf_len = len;
+ cppi_ch->channel.actual_len = 0;
+
+ /* TX channel? or RX? */
+ if (cppi_ch->transmit)
+ cppi_next_tx_segment(musb, cppi_ch);
+ else
+ cppi_next_rx_segment(musb, cppi_ch, mode);
+
+ return true;
+}
+
+static bool cppi_rx_scan(struct cppi *cppi, unsigned ch)
+{
+ struct cppi_channel *rx = &cppi->rx[ch];
+ struct cppi_rx_stateram __iomem *state = rx->state_ram;
+ struct cppi_descriptor *bd;
+ struct cppi_descriptor *last = rx->last_processed;
+ bool completed = false;
+ bool acked = false;
+ int i;
+ dma_addr_t safe2ack;
+ void __iomem *regs = rx->hw_ep->regs;
+ struct musb *musb = cppi->musb;
+
+ cppi_dump_rx(6, rx, "/K");
+
+ bd = last ? last->next : rx->head;
+ if (!bd)
+ return false;
+
+ /* run through all completed BDs */
+ for (i = 0, safe2ack = musb_readl(&state->rx_complete, 0);
+ (safe2ack || completed) && bd && i < NUM_RXCHAN_BD;
+ i++, bd = bd->next) {
+ u16 len;
+
+ /* catch latest BD writes from CPPI */
+ rmb();
+ if (!completed && (bd->hw_options & CPPI_OWN_SET))
+ break;
+
+ dev_dbg(musb->controller, "C/RXBD %llx: nxt %08x buf %08x "
+ "off.len %08x opt.len %08x (%d)\n",
+ (unsigned long long)bd->dma, bd->hw_next, bd->hw_bufp,
+ bd->hw_off_len, bd->hw_options,
+ rx->channel.actual_len);
+
+ /* actual packet received length */
+ if ((bd->hw_options & CPPI_SOP_SET) && !completed)
+ len = bd->hw_off_len & CPPI_RECV_PKTLEN_MASK;
+ else
+ len = 0;
+
+ if (bd->hw_options & CPPI_EOQ_MASK)
+ completed = true;
+
+ if (!completed && len < bd->buflen) {
+ /* NOTE: when we get a short packet, RXCSR_H_REQPKT
+ * must have been cleared, and no more DMA packets may
+ * active be in the queue... TI docs didn't say, but
+ * CPPI ignores those BDs even though OWN is still set.
+ */
+ completed = true;
+ dev_dbg(musb->controller, "rx short %d/%d (%d)\n",
+ len, bd->buflen,
+ rx->channel.actual_len);
+ }
+
+ /* If we got here, we expect to ack at least one BD; meanwhile
+ * CPPI may completing other BDs while we scan this list...
+ *
+ * RACE: we can notice OWN cleared before CPPI raises the
+ * matching irq by writing that BD as the completion pointer.
+ * In such cases, stop scanning and wait for the irq, avoiding
+ * lost acks and states where BD ownership is unclear.
+ */
+ if (bd->dma == safe2ack) {
+ musb_writel(&state->rx_complete, 0, safe2ack);
+ safe2ack = musb_readl(&state->rx_complete, 0);
+ acked = true;
+ if (bd->dma == safe2ack)
+ safe2ack = 0;
+ }
+
+ rx->channel.actual_len += len;
+
+ cppi_bd_free(rx, last);
+ last = bd;
+
+ /* stop scanning on end-of-segment */
+ if (bd->hw_next == 0)
+ completed = true;
+ }
+ rx->last_processed = last;
+
+ /* dma abort, lost ack, or ... */
+ if (!acked && last) {
+ int csr;
+
+ if (safe2ack == 0 || safe2ack == rx->last_processed->dma)
+ musb_writel(&state->rx_complete, 0, safe2ack);
+ if (safe2ack == 0) {
+ cppi_bd_free(rx, last);
+ rx->last_processed = NULL;
+
+ /* if we land here on the host side, H_REQPKT will
+ * be clear and we need to restart the queue...
+ */
+ WARN_ON(rx->head);
+ }
+ musb_ep_select(cppi->mregs, rx->index + 1);
+ csr = musb_readw(regs, MUSB_RXCSR);
+ if (csr & MUSB_RXCSR_DMAENAB) {
+ dev_dbg(musb->controller, "list%d %p/%p, last %llx%s, csr %04x\n",
+ rx->index,
+ rx->head, rx->tail,
+ rx->last_processed
+ ? (unsigned long long)
+ rx->last_processed->dma
+ : 0,
+ completed ? ", completed" : "",
+ csr);
+ cppi_dump_rxq(4, "/what?", rx);
+ }
+ }
+ if (!completed) {
+ int csr;
+
+ rx->head = bd;
+
+ /* REVISIT seems like "autoreq all but EOP" doesn't...
+ * setting it here "should" be racey, but seems to work
+ */
+ csr = musb_readw(rx->hw_ep->regs, MUSB_RXCSR);
+ if (is_host_active(cppi->musb)
+ && bd
+ && !(csr & MUSB_RXCSR_H_REQPKT)) {
+ csr |= MUSB_RXCSR_H_REQPKT;
+ musb_writew(regs, MUSB_RXCSR,
+ MUSB_RXCSR_H_WZC_BITS | csr);
+ csr = musb_readw(rx->hw_ep->regs, MUSB_RXCSR);
+ }
+ } else {
+ rx->head = NULL;
+ rx->tail = NULL;
+ }
+
+ cppi_dump_rx(6, rx, completed ? "/completed" : "/cleaned");
+ return completed;
+}
+
+irqreturn_t cppi_interrupt(int irq, void *dev_id)
+{
+ struct musb *musb = dev_id;
+ struct cppi *cppi;
+ void __iomem *tibase;
+ struct musb_hw_ep *hw_ep = NULL;
+ u32 rx, tx;
+ int i, index;
+ unsigned long uninitialized_var(flags);
+
+ cppi = container_of(musb->dma_controller, struct cppi, controller);
+ if (cppi->irq)
+ spin_lock_irqsave(&musb->lock, flags);
+
+ tibase = musb->ctrl_base;
+
+ tx = musb_readl(tibase, DAVINCI_TXCPPI_MASKED_REG);
+ rx = musb_readl(tibase, DAVINCI_RXCPPI_MASKED_REG);
+
+ if (!tx && !rx) {
+ if (cppi->irq)
+ spin_unlock_irqrestore(&musb->lock, flags);
+ return IRQ_NONE;
+ }
+
+ dev_dbg(musb->controller, "CPPI IRQ Tx%x Rx%x\n", tx, rx);
+
+ /* process TX channels */
+ for (index = 0; tx; tx = tx >> 1, index++) {
+ struct cppi_channel *tx_ch;
+ struct cppi_tx_stateram __iomem *tx_ram;
+ bool completed = false;
+ struct cppi_descriptor *bd;
+
+ if (!(tx & 1))
+ continue;
+
+ tx_ch = cppi->tx + index;
+ tx_ram = tx_ch->state_ram;
+
+ /* FIXME need a cppi_tx_scan() routine, which
+ * can also be called from abort code
+ */
+
+ cppi_dump_tx(5, tx_ch, "/E");
+
+ bd = tx_ch->head;
+
+ /*
+ * If Head is null then this could mean that a abort interrupt
+ * that needs to be acknowledged.
+ */
+ if (NULL == bd) {
+ dev_dbg(musb->controller, "null BD\n");
+ musb_writel(&tx_ram->tx_complete, 0, 0);
+ continue;
+ }
+
+ /* run through all completed BDs */
+ for (i = 0; !completed && bd && i < NUM_TXCHAN_BD;
+ i++, bd = bd->next) {
+ u16 len;
+
+ /* catch latest BD writes from CPPI */
+ rmb();
+ if (bd->hw_options & CPPI_OWN_SET)
+ break;
+
+ dev_dbg(musb->controller, "C/TXBD %p n %x b %x off %x opt %x\n",
+ bd, bd->hw_next, bd->hw_bufp,
+ bd->hw_off_len, bd->hw_options);
+
+ len = bd->hw_off_len & CPPI_BUFFER_LEN_MASK;
+ tx_ch->channel.actual_len += len;
+
+ tx_ch->last_processed = bd;
+
+ /* write completion register to acknowledge
+ * processing of completed BDs, and possibly
+ * release the IRQ; EOQ might not be set ...
+ *
+ * REVISIT use the same ack strategy as rx
+ *
+ * REVISIT have observed bit 18 set; huh??
+ */
+ /* if ((bd->hw_options & CPPI_EOQ_MASK)) */
+ musb_writel(&tx_ram->tx_complete, 0, bd->dma);
+
+ /* stop scanning on end-of-segment */
+ if (bd->hw_next == 0)
+ completed = true;
+ }
+
+ /* on end of segment, maybe go to next one */
+ if (completed) {
+ /* cppi_dump_tx(4, tx_ch, "/complete"); */
+
+ /* transfer more, or report completion */
+ if (tx_ch->offset >= tx_ch->buf_len) {
+ tx_ch->head = NULL;
+ tx_ch->tail = NULL;
+ tx_ch->channel.status = MUSB_DMA_STATUS_FREE;
+
+ hw_ep = tx_ch->hw_ep;
+
+ musb_dma_completion(musb, index + 1, 1);
+
+ } else {
+ /* Bigger transfer than we could fit in
+ * that first batch of descriptors...
+ */
+ cppi_next_tx_segment(musb, tx_ch);
+ }
+ } else
+ tx_ch->head = bd;
+ }
+
+ /* Start processing the RX block */
+ for (index = 0; rx; rx = rx >> 1, index++) {
+
+ if (rx & 1) {
+ struct cppi_channel *rx_ch;
+
+ rx_ch = cppi->rx + index;
+
+ /* let incomplete dma segments finish */
+ if (!cppi_rx_scan(cppi, index))
+ continue;
+
+ /* start another dma segment if needed */
+ if (rx_ch->channel.actual_len != rx_ch->buf_len
+ && rx_ch->channel.actual_len
+ == rx_ch->offset) {
+ cppi_next_rx_segment(musb, rx_ch, 1);
+ continue;
+ }
+
+ /* all segments completed! */
+ rx_ch->channel.status = MUSB_DMA_STATUS_FREE;
+
+ hw_ep = rx_ch->hw_ep;
+
+ core_rxirq_disable(tibase, index + 1);
+ musb_dma_completion(musb, index + 1, 0);
+ }
+ }
+
+ /* write to CPPI EOI register to re-enable interrupts */
+ musb_writel(tibase, DAVINCI_CPPI_EOI_REG, 0);
+
+ if (cppi->irq)
+ spin_unlock_irqrestore(&musb->lock, flags);
+
+ return IRQ_HANDLED;
+}
+EXPORT_SYMBOL_GPL(cppi_interrupt);
+
+/* Instantiate a software object representing a DMA controller. */
+struct dma_controller *dma_controller_create(struct musb *musb, void __iomem *mregs)
+{
+ struct cppi *controller;
+ struct device *dev = musb->controller;
+ struct platform_device *pdev = to_platform_device(dev);
+ int irq = platform_get_irq_byname(pdev, "dma");
+
+ controller = kzalloc(sizeof *controller, GFP_KERNEL);
+ if (!controller)
+ return NULL;
+
+ controller->mregs = mregs;
+ controller->tibase = mregs - DAVINCI_BASE_OFFSET;
+
+ controller->musb = musb;
+ controller->controller.channel_alloc = cppi_channel_allocate;
+ controller->controller.channel_release = cppi_channel_release;
+ controller->controller.channel_program = cppi_channel_program;
+ controller->controller.channel_abort = cppi_channel_abort;
+
+ /* NOTE: allocating from on-chip SRAM would give the least
+ * contention for memory access, if that ever matters here.
+ */
+
+ /* setup BufferPool */
+ controller->pool = dma_pool_create("cppi",
+ controller->musb->controller,
+ sizeof(struct cppi_descriptor),
+ CPPI_DESCRIPTOR_ALIGN, 0);
+ if (!controller->pool) {
+ kfree(controller);
+ return NULL;
+ }
+
+ if (irq > 0) {
+ if (request_irq(irq, cppi_interrupt, 0, "cppi-dma", musb)) {
+ dev_err(dev, "request_irq %d failed!\n", irq);
+ dma_controller_destroy(&controller->controller);
+ return NULL;
+ }
+ controller->irq = irq;
+ }
+
+ cppi_controller_start(controller);
+ return &controller->controller;
+}
+
+/*
+ * Destroy a previously-instantiated DMA controller.
+ */
+void dma_controller_destroy(struct dma_controller *c)
+{
+ struct cppi *cppi;
+
+ cppi = container_of(c, struct cppi, controller);
+
+ cppi_controller_stop(cppi);
+
+ if (cppi->irq)
+ free_irq(cppi->irq, cppi->musb);
+
+ /* assert: caller stopped the controller first */
+ dma_pool_destroy(cppi->pool);
+
+ kfree(cppi);
+}
+
+/*
+ * Context: controller irqlocked, endpoint selected
+ */
+static int cppi_channel_abort(struct dma_channel *channel)
+{
+ struct cppi_channel *cppi_ch;
+ struct cppi *controller;
+ void __iomem *mbase;
+ void __iomem *tibase;
+ void __iomem *regs;
+ u32 value;
+ struct cppi_descriptor *queue;
+
+ cppi_ch = container_of(channel, struct cppi_channel, channel);
+
+ controller = cppi_ch->controller;
+
+ switch (channel->status) {
+ case MUSB_DMA_STATUS_BUS_ABORT:
+ case MUSB_DMA_STATUS_CORE_ABORT:
+ /* from RX or TX fault irq handler */
+ case MUSB_DMA_STATUS_BUSY:
+ /* the hardware needs shutting down */
+ regs = cppi_ch->hw_ep->regs;
+ break;
+ case MUSB_DMA_STATUS_UNKNOWN:
+ case MUSB_DMA_STATUS_FREE:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+
+ if (!cppi_ch->transmit && cppi_ch->head)
+ cppi_dump_rxq(3, "/abort", cppi_ch);
+
+ mbase = controller->mregs;
+ tibase = controller->tibase;
+
+ queue = cppi_ch->head;
+ cppi_ch->head = NULL;
+ cppi_ch->tail = NULL;
+
+ /* REVISIT should rely on caller having done this,
+ * and caller should rely on us not changing it.
+ * peripheral code is safe ... check host too.
+ */
+ musb_ep_select(mbase, cppi_ch->index + 1);
+
+ if (cppi_ch->transmit) {
+ struct cppi_tx_stateram __iomem *tx_ram;
+ /* REVISIT put timeouts on these controller handshakes */
+
+ cppi_dump_tx(6, cppi_ch, " (teardown)");
+
+ /* teardown DMA engine then usb core */
+ do {
+ value = musb_readl(tibase, DAVINCI_TXCPPI_TEAR_REG);
+ } while (!(value & CPPI_TEAR_READY));
+ musb_writel(tibase, DAVINCI_TXCPPI_TEAR_REG, cppi_ch->index);
+
+ tx_ram = cppi_ch->state_ram;
+ do {
+ value = musb_readl(&tx_ram->tx_complete, 0);
+ } while (0xFFFFFFFC != value);
+
+ /* FIXME clean up the transfer state ... here?
+ * the completion routine should get called with
+ * an appropriate status code.
+ */
+
+ value = musb_readw(regs, MUSB_TXCSR);
+ value &= ~MUSB_TXCSR_DMAENAB;
+ value |= MUSB_TXCSR_FLUSHFIFO;
+ musb_writew(regs, MUSB_TXCSR, value);
+ musb_writew(regs, MUSB_TXCSR, value);
+
+ /*
+ * 1. Write to completion Ptr value 0x1(bit 0 set)
+ * (write back mode)
+ * 2. Wait for abort interrupt and then put the channel in
+ * compare mode by writing 1 to the tx_complete register.
+ */
+ cppi_reset_tx(tx_ram, 1);
+ cppi_ch->head = NULL;
+ musb_writel(&tx_ram->tx_complete, 0, 1);
+ cppi_dump_tx(5, cppi_ch, " (done teardown)");
+
+ /* REVISIT tx side _should_ clean up the same way
+ * as the RX side ... this does no cleanup at all!
+ */
+
+ } else /* RX */ {
+ u16 csr;
+
+ /* NOTE: docs don't guarantee any of this works ... we
+ * expect that if the usb core stops telling the cppi core
+ * to pull more data from it, then it'll be safe to flush
+ * current RX DMA state iff any pending fifo transfer is done.
+ */
+
+ core_rxirq_disable(tibase, cppi_ch->index + 1);
+
+ /* for host, ensure ReqPkt is never set again */
+ if (is_host_active(cppi_ch->controller->musb)) {
+ value = musb_readl(tibase, DAVINCI_AUTOREQ_REG);
+ value &= ~((0x3) << (cppi_ch->index * 2));
+ musb_writel(tibase, DAVINCI_AUTOREQ_REG, value);
+ }
+
+ csr = musb_readw(regs, MUSB_RXCSR);
+
+ /* for host, clear (just) ReqPkt at end of current packet(s) */
+ if (is_host_active(cppi_ch->controller->musb)) {
+ csr |= MUSB_RXCSR_H_WZC_BITS;
+ csr &= ~MUSB_RXCSR_H_REQPKT;
+ } else
+ csr |= MUSB_RXCSR_P_WZC_BITS;
+
+ /* clear dma enable */
+ csr &= ~(MUSB_RXCSR_DMAENAB);
+ musb_writew(regs, MUSB_RXCSR, csr);
+ csr = musb_readw(regs, MUSB_RXCSR);
+
+ /* Quiesce: wait for current dma to finish (if not cleanup).
+ * We can't use bit zero of stateram->rx_sop, since that
+ * refers to an entire "DMA packet" not just emptying the
+ * current fifo. Most segments need multiple usb packets.
+ */
+ if (channel->status == MUSB_DMA_STATUS_BUSY)
+ udelay(50);
+
+ /* scan the current list, reporting any data that was
+ * transferred and acking any IRQ
+ */
+ cppi_rx_scan(controller, cppi_ch->index);
+
+ /* clobber the existing state once it's idle
+ *
+ * NOTE: arguably, we should also wait for all the other
+ * RX channels to quiesce (how??) and then temporarily
+ * disable RXCPPI_CTRL_REG ... but it seems that we can
+ * rely on the controller restarting from state ram, with
+ * only RXCPPI_BUFCNT state being bogus. BUFCNT will
+ * correct itself after the next DMA transfer though.
+ *
+ * REVISIT does using rndis mode change that?
+ */
+ cppi_reset_rx(cppi_ch->state_ram);
+
+ /* next DMA request _should_ load cppi head ptr */
+
+ /* ... we don't "free" that list, only mutate it in place. */
+ cppi_dump_rx(5, cppi_ch, " (done abort)");
+
+ /* clean up previously pending bds */
+ cppi_bd_free(cppi_ch, cppi_ch->last_processed);
+ cppi_ch->last_processed = NULL;
+
+ while (queue) {
+ struct cppi_descriptor *tmp = queue->next;
+
+ cppi_bd_free(cppi_ch, queue);
+ queue = tmp;
+ }
+ }
+
+ channel->status = MUSB_DMA_STATUS_FREE;
+ cppi_ch->buf_dma = 0;
+ cppi_ch->offset = 0;
+ cppi_ch->buf_len = 0;
+ cppi_ch->maxpacket = 0;
+ return 0;
+}
+
+/* TBD Queries:
+ *
+ * Power Management ... probably turn off cppi during suspend, restart;
+ * check state ram? Clocking is presumably shared with usb core.
+ */
Code Review / kvmfornfv.git / blobdiff