Openwrt/openwrt/package/linux/kernel-source/drivers/net/hnd/hnddma.c

842 lines
20 KiB
C

/*
* Generic Broadcom Home Networking Division (HND) DMA module.
* This supports the following chips: BCM42xx, 44xx, 47xx .
*
* Copyright 2004, Broadcom Corporation
* All Rights Reserved.
*
* THIS SOFTWARE IS OFFERED "AS IS", AND BROADCOM GRANTS NO WARRANTIES OF ANY
* KIND, EXPRESS OR IMPLIED, BY STATUTE, COMMUNICATION OR OTHERWISE. BROADCOM
* SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A SPECIFIC PURPOSE OR NONINFRINGEMENT CONCERNING THIS SOFTWARE.
*
* $Id$
*/
#include <typedefs.h>
#include <osl.h>
#include <bcmendian.h>
#include <bcmutils.h>
struct dma_info; /* forward declaration */
#define di_t struct dma_info
#include <hnddma.h>
/* debug/trace */
#define DMA_ERROR(args)
#define DMA_TRACE(args)
/* default dma message level(if input msg_level pointer is null in dma_attach()) */
static uint dma_msg_level = 0;
#define MAXNAMEL 8
#define MAXDD (DMAMAXRINGSZ / sizeof (dmadd_t))
/* dma engine software state */
typedef struct dma_info {
hnddma_t hnddma; /* exported structure */
uint *msg_level; /* message level pointer */
char name[MAXNAMEL]; /* callers name for diag msgs */
void *drv; /* driver handle */
void *dev; /* device handle */
dmaregs_t *regs; /* dma engine registers */
dmadd_t *txd; /* pointer to chip-specific tx descriptor ring */
uint txin; /* index of next descriptor to reclaim */
uint txout; /* index of next descriptor to post */
uint txavail; /* # free tx descriptors */
void *txp[MAXDD]; /* parallel array of pointers to packets */
ulong txdpa; /* physical address of descriptor ring */
uint txdalign; /* #bytes added to alloc'd mem to align txd */
dmadd_t *rxd; /* pointer to chip-specific rx descriptor ring */
uint rxin; /* index of next descriptor to reclaim */
uint rxout; /* index of next descriptor to post */
void *rxp[MAXDD]; /* parallel array of pointers to packets */
ulong rxdpa; /* physical address of descriptor ring */
uint rxdalign; /* #bytes added to alloc'd mem to align rxd */
/* tunables */
uint ntxd; /* # tx descriptors */
uint nrxd; /* # rx descriptors */
uint rxbufsize; /* rx buffer size in bytes */
uint nrxpost; /* # rx buffers to keep posted */
uint rxoffset; /* rxcontrol offset */
uint ddoffset; /* add to get dma address of descriptor ring */
uint dataoffset; /* add to get dma address of data buffer */
} dma_info_t;
/* descriptor bumping macros */
#define TXD(x) ((x) & (di->ntxd - 1))
#define RXD(x) ((x) & (di->nrxd - 1))
#define NEXTTXD(i) TXD(i + 1)
#define PREVTXD(i) TXD(i - 1)
#define NEXTRXD(i) RXD(i + 1)
#define NTXDACTIVE(h, t) TXD(t - h)
#define NRXDACTIVE(h, t) RXD(t - h)
/* macros to convert between byte offsets and indexes */
#define B2I(bytes) ((bytes) / sizeof (dmadd_t))
#define I2B(index) ((index) * sizeof (dmadd_t))
void*
dma_attach(void *drv, void *dev, char *name, dmaregs_t *regs, uint ntxd, uint nrxd,
uint rxbufsize, uint nrxpost, uint rxoffset, uint ddoffset, uint dataoffset, uint *msg_level)
{
dma_info_t *di;
void *va;
ASSERT(ntxd <= MAXDD);
ASSERT(nrxd <= MAXDD);
/* allocate private info structure */
if ((di = MALLOC(sizeof (dma_info_t))) == NULL)
return (NULL);
bzero((char*)di, sizeof (dma_info_t));
/* set message level */
di->msg_level = msg_level ? msg_level : &dma_msg_level;
DMA_TRACE(("%s: dma_attach: drv 0x%x dev 0x%x regs 0x%x ntxd %d nrxd %d rxbufsize %d nrxpost %d rxoffset %d ddoffset 0x%x dataoffset 0x%x\n", name, (uint)drv, (uint)dev, (uint)regs, ntxd, nrxd, rxbufsize, nrxpost, rxoffset, ddoffset, dataoffset));
/* make a private copy of our callers name */
strncpy(di->name, name, MAXNAMEL);
di->name[MAXNAMEL-1] = '\0';
di->drv = drv;
di->dev = dev;
di->regs = regs;
/* allocate transmit descriptor ring */
if (ntxd) {
if ((va = DMA_ALLOC_CONSISTENT(dev, (DMAMAXRINGSZ + DMARINGALIGN), &di->txdpa)) == NULL)
goto fail;
di->txd = (dmadd_t*) ROUNDUP(va, DMARINGALIGN);
di->txdalign = ((uint)di->txd - (uint)va);
di->txdpa = di->txdpa + di->txdalign;
ASSERT(ISALIGNED(di->txd, DMARINGALIGN));
}
/* allocate receive descriptor ring */
if (nrxd) {
if ((va = DMA_ALLOC_CONSISTENT(dev, (DMAMAXRINGSZ + DMARINGALIGN), &di->rxdpa)) == NULL)
goto fail;
di->rxd = (dmadd_t*) ROUNDUP(va, DMARINGALIGN);
di->rxdalign = ((uint)di->rxd - (uint)va);
di->rxdpa = di->rxdpa + di->rxdalign;
ASSERT(ISALIGNED(di->rxd, DMARINGALIGN));
}
/* save tunables */
di->ntxd = ntxd;
di->nrxd = nrxd;
di->rxbufsize = rxbufsize;
di->nrxpost = nrxpost;
di->rxoffset = rxoffset;
di->ddoffset = ddoffset;
di->dataoffset = dataoffset;
return ((void*)di);
fail:
dma_detach((void*)di);
return (NULL);
}
/* may be called with core in reset */
void
dma_detach(dma_info_t *di)
{
if (di == NULL)
return;
DMA_TRACE(("%s: dma_detach\n", di->name));
/* shouldn't be here if descriptors are unreclaimed */
ASSERT(di->txin == di->txout);
ASSERT(di->rxin == di->rxout);
/* free dma descriptor rings */
if (di->txd)
DMA_FREE_CONSISTENT(di->dev, (void *)((uint)di->txd - di->txdalign), (DMAMAXRINGSZ + DMARINGALIGN), di->txdpa);
if (di->rxd)
DMA_FREE_CONSISTENT(di->dev, (void *)((uint)di->rxd - di->rxdalign), (DMAMAXRINGSZ + DMARINGALIGN), di->rxdpa);
/* free our private info structure */
MFREE((void*)di, sizeof (dma_info_t));
}
void
dma_txreset(dma_info_t *di)
{
uint32 status;
DMA_TRACE(("%s: dma_txreset\n", di->name));
/* suspend tx DMA first */
W_REG(&di->regs->xmtcontrol, XC_SE);
SPINWAIT((status = (R_REG(&di->regs->xmtstatus) & XS_XS_MASK)) != XS_XS_DISABLED &&
status != XS_XS_IDLE &&
status != XS_XS_STOPPED,
10000);
W_REG(&di->regs->xmtcontrol, 0);
SPINWAIT((status = (R_REG(&di->regs->xmtstatus) & XS_XS_MASK)) != XS_XS_DISABLED,
10000);
if (status != XS_XS_DISABLED) {
DMA_ERROR(("%s: dma_txreset: dma cannot be stopped\n", di->name));
}
/* wait for the last transaction to complete */
OSL_DELAY(300);
}
void
dma_rxreset(dma_info_t *di)
{
uint32 status;
DMA_TRACE(("%s: dma_rxreset\n", di->name));
W_REG(&di->regs->rcvcontrol, 0);
SPINWAIT((status = (R_REG(&di->regs->rcvstatus) & RS_RS_MASK)) != RS_RS_DISABLED,
10000);
if (status != RS_RS_DISABLED) {
DMA_ERROR(("%s: dma_rxreset: dma cannot be stopped\n", di->name));
}
}
void
dma_txinit(dma_info_t *di)
{
DMA_TRACE(("%s: dma_txinit\n", di->name));
di->txin = di->txout = 0;
di->txavail = di->ntxd - 1;
/* clear tx descriptor ring */
BZERO_SM((void*)di->txd, (di->ntxd * sizeof (dmadd_t)));
W_REG(&di->regs->xmtcontrol, XC_XE);
W_REG(&di->regs->xmtaddr, (di->txdpa + di->ddoffset));
}
bool
dma_txenabled(dma_info_t *di)
{
uint32 xc;
/* If the chip is dead, it is not enabled :-) */
xc = R_REG(&di->regs->xmtcontrol);
return ((xc != 0xffffffff) && (xc & XC_XE));
}
void
dma_txsuspend(dma_info_t *di)
{
DMA_TRACE(("%s: dma_txsuspend\n", di->name));
OR_REG(&di->regs->xmtcontrol, XC_SE);
}
void
dma_txresume(dma_info_t *di)
{
DMA_TRACE(("%s: dma_txresume\n", di->name));
AND_REG(&di->regs->xmtcontrol, ~XC_SE);
}
bool
dma_txsuspended(dma_info_t *di)
{
if (!(R_REG(&di->regs->xmtcontrol) & XC_SE))
return 0;
if ((R_REG(&di->regs->xmtstatus) & XS_XS_MASK) != XS_XS_IDLE)
return 0;
OSL_DELAY(2);
return ((R_REG(&di->regs->xmtstatus) & XS_XS_MASK) == XS_XS_IDLE);
}
bool
dma_txstopped(dma_info_t *di)
{
return ((R_REG(&di->regs->xmtstatus) & XS_XS_MASK) == XS_XS_STOPPED);
}
bool
dma_rxstopped(dma_info_t *di)
{
return ((R_REG(&di->regs->rcvstatus) & RS_RS_MASK) == RS_RS_STOPPED);
}
void
dma_fifoloopbackenable(dma_info_t *di)
{
DMA_TRACE(("%s: dma_fifoloopbackenable\n", di->name));
OR_REG(&di->regs->xmtcontrol, XC_LE);
}
void
dma_rxinit(dma_info_t *di)
{
DMA_TRACE(("%s: dma_rxinit\n", di->name));
di->rxin = di->rxout = 0;
/* clear rx descriptor ring */
BZERO_SM((void*)di->rxd, (di->nrxd * sizeof (dmadd_t)));
dma_rxenable(di);
W_REG(&di->regs->rcvaddr, (di->rxdpa + di->ddoffset));
}
void
dma_rxenable(dma_info_t *di)
{
DMA_TRACE(("%s: dma_rxenable\n", di->name));
W_REG(&di->regs->rcvcontrol, ((di->rxoffset << RC_RO_SHIFT) | RC_RE));
}
bool
dma_rxenabled(dma_info_t *di)
{
uint32 rc;
rc = R_REG(&di->regs->rcvcontrol);
return ((rc != 0xffffffff) && (rc & RC_RE));
}
/*
* The BCM47XX family supports full 32bit dma engine buffer addressing so
* dma buffers can cross 4 Kbyte page boundaries.
*/
int
dma_txfast(dma_info_t *di, void *p0, uint32 coreflags)
{
void *p, *next;
uchar *data;
uint len;
uint txout;
uint32 ctrl;
uint32 pa;
DMA_TRACE(("%s: dma_txfast\n", di->name));
txout = di->txout;
ctrl = 0;
/*
* Walk the chain of packet buffers
* allocating and initializing transmit descriptor entries.
*/
for (p = p0; p; p = next) {
data = PKTDATA(di->drv, p);
len = PKTLEN(di->drv, p);
next = PKTNEXT(di->drv, p);
/* return nonzero if out of tx descriptors */
if (NEXTTXD(txout) == di->txin)
goto outoftxd;
if (len == 0)
continue;
/* get physical address of buffer start */
pa = (uint32) DMA_MAP(di->dev, data, len, DMA_TX, p);
/* build the descriptor control value */
ctrl = len & CTRL_BC_MASK;
ctrl |= coreflags;
if (p == p0)
ctrl |= CTRL_SOF;
if (next == NULL)
ctrl |= (CTRL_IOC | CTRL_EOF);
if (txout == (di->ntxd - 1))
ctrl |= CTRL_EOT;
/* init the tx descriptor */
W_SM(&di->txd[txout].ctrl, BUS_SWAP32(ctrl));
W_SM(&di->txd[txout].addr, BUS_SWAP32(pa + di->dataoffset));
ASSERT(di->txp[txout] == NULL);
txout = NEXTTXD(txout);
}
/* if last txd eof not set, fix it */
if (!(ctrl & CTRL_EOF))
W_SM(&di->txd[PREVTXD(txout)].ctrl, BUS_SWAP32(ctrl | CTRL_IOC | CTRL_EOF));
/* save the packet */
di->txp[PREVTXD(txout)] = p0;
/* bump the tx descriptor index */
di->txout = txout;
/* kick the chip */
W_REG(&di->regs->xmtptr, I2B(txout));
/* tx flow control */
di->txavail = di->ntxd - NTXDACTIVE(di->txin, di->txout) - 1;
return (0);
outoftxd:
DMA_ERROR(("%s: dma_txfast: out of txds\n", di->name));
PKTFREE(di->drv, p0, TRUE);
di->txavail = 0;
di->hnddma.txnobuf++;
return (-1);
}
#define PAGESZ 4096
#define PAGEBASE(x) ((uint)(x) & ~4095)
/*
* Just like above except go through the extra effort of splitting
* buffers that cross 4Kbyte boundaries into multiple tx descriptors.
*/
int
dma_tx(dma_info_t *di, void *p0, uint32 coreflags)
{
void *p, *next;
uchar *data;
uint plen, len;
uchar *page, *start, *end;
uint txout;
uint32 ctrl;
uint32 pa;
DMA_TRACE(("%s: dma_tx\n", di->name));
txout = di->txout;
ctrl = 0;
/*
* Walk the chain of packet buffers
* splitting those that cross 4 Kbyte boundaries
* allocating and initializing transmit descriptor entries.
*/
for (p = p0; p; p = next) {
data = PKTDATA(di->drv, p);
plen = PKTLEN(di->drv, p);
next = PKTNEXT(di->drv, p);
if (plen == 0)
continue;
for (page = (uchar*)PAGEBASE(data);
page <= (uchar*)PAGEBASE(data + plen - 1);
page += PAGESZ) {
/* return nonzero if out of tx descriptors */
if (NEXTTXD(txout) == di->txin)
goto outoftxd;
start = (page == (uchar*)PAGEBASE(data))? data: page;
end = (page == (uchar*)PAGEBASE(data + plen))?
(data + plen): (page + PAGESZ);
len = end - start;
/* build the descriptor control value */
ctrl = len & CTRL_BC_MASK;
ctrl |= coreflags;
if ((p == p0) && (start == data))
ctrl |= CTRL_SOF;
if ((next == NULL) && (end == (data + plen)))
ctrl |= (CTRL_IOC | CTRL_EOF);
if (txout == (di->ntxd - 1))
ctrl |= CTRL_EOT;
/* get physical address of buffer start */
pa = (uint32) DMA_MAP(di->dev, start, len, DMA_TX, p);
/* init the tx descriptor */
W_SM(&di->txd[txout].ctrl, BUS_SWAP32(ctrl));
W_SM(&di->txd[txout].addr, BUS_SWAP32(pa + di->dataoffset));
ASSERT(di->txp[txout] == NULL);
txout = NEXTTXD(txout);
}
}
/* if last txd eof not set, fix it */
if (!(ctrl & CTRL_EOF))
W_SM(&di->txd[PREVTXD(txout)].ctrl, BUS_SWAP32(ctrl | CTRL_IOC | CTRL_EOF));
/* save the packet */
di->txp[PREVTXD(txout)] = p0;
/* bump the tx descriptor index */
di->txout = txout;
/* kick the chip */
W_REG(&di->regs->xmtptr, I2B(txout));
/* tx flow control */
di->txavail = di->ntxd - NTXDACTIVE(di->txin, di->txout) - 1;
return (0);
outoftxd:
DMA_ERROR(("%s: dma_tx: out of txds\n", di->name));
PKTFREE(di->drv, p0, TRUE);
di->txavail = 0;
di->hnddma.txnobuf++;
return (-1);
}
/* returns a pointer to the next frame received, or NULL if there are no more */
void*
dma_rx(dma_info_t *di)
{
void *p;
uint len;
int skiplen = 0;
while ((p = dma_getnextrxp(di, FALSE))) {
/* skip giant packets which span multiple rx descriptors */
if (skiplen > 0) {
skiplen -= di->rxbufsize;
if (skiplen < 0)
skiplen = 0;
PKTFREE(di->drv, p, FALSE);
continue;
}
len = ltoh16(*(uint16*)(PKTDATA(di->drv, p)));
DMA_TRACE(("%s: dma_rx len %d\n", di->name, len));
/* bad frame length check */
if (len > (di->rxbufsize - di->rxoffset)) {
DMA_ERROR(("%s: dma_rx: bad frame length (%d)\n", di->name, len));
if (len > 0)
skiplen = len - (di->rxbufsize - di->rxoffset);
PKTFREE(di->drv, p, FALSE);
di->hnddma.rxgiants++;
continue;
}
/* set actual length */
PKTSETLEN(di->drv, p, (di->rxoffset + len));
break;
}
return (p);
}
/* post receive buffers */
void
dma_rxfill(dma_info_t *di)
{
void *p;
uint rxin, rxout;
uint ctrl;
uint n;
uint i;
uint32 pa;
uint rxbufsize;
/*
* Determine how many receive buffers we're lacking
* from the full complement, allocate, initialize,
* and post them, then update the chip rx lastdscr.
*/
rxin = di->rxin;
rxout = di->rxout;
rxbufsize = di->rxbufsize;
n = di->nrxpost - NRXDACTIVE(rxin, rxout);
DMA_TRACE(("%s: dma_rxfill: post %d\n", di->name, n));
for (i = 0; i < n; i++) {
if ((p = PKTGET(di->drv, rxbufsize, FALSE)) == NULL) {
DMA_ERROR(("%s: dma_rxfill: out of rxbufs\n", di->name));
di->hnddma.rxnobuf++;
break;
}
*(uint32*)(OSL_UNCACHED(PKTDATA(di->drv, p))) = 0;
pa = (uint32) DMA_MAP(di->dev, PKTDATA(di->drv, p), rxbufsize, DMA_RX, p);
ASSERT(ISALIGNED(pa, 4));
/* save the free packet pointer */
ASSERT(di->rxp[rxout] == NULL);
di->rxp[rxout] = p;
/* prep the descriptor control value */
ctrl = rxbufsize;
if (rxout == (di->nrxd - 1))
ctrl |= CTRL_EOT;
/* init the rx descriptor */
W_SM(&di->rxd[rxout].ctrl, BUS_SWAP32(ctrl));
W_SM(&di->rxd[rxout].addr, BUS_SWAP32(pa + di->dataoffset));
rxout = NEXTRXD(rxout);
}
di->rxout = rxout;
/* update the chip lastdscr pointer */
W_REG(&di->regs->rcvptr, I2B(rxout));
}
void
dma_txreclaim(dma_info_t *di, bool forceall)
{
void *p;
DMA_TRACE(("%s: dma_txreclaim %s\n", di->name, forceall ? "all" : ""));
while ((p = dma_getnexttxp(di, forceall)))
PKTFREE(di->drv, p, TRUE);
}
/*
* Reclaim next completed txd (txds if using chained buffers) and
* return associated packet.
* If 'force' is true, reclaim txd(s) and return associated packet
* regardless of the value of the hardware "curr" pointer.
*/
void*
dma_getnexttxp(dma_info_t *di, bool forceall)
{
uint start, end, i;
void *txp;
DMA_TRACE(("%s: dma_getnexttxp %s\n", di->name, forceall ? "all" : ""));
txp = NULL;
start = di->txin;
if (forceall)
end = di->txout;
else
end = B2I(R_REG(&di->regs->xmtstatus) & XS_CD_MASK);
if ((start == 0) && (end > di->txout))
goto bogus;
for (i = start; i != end && !txp; i = NEXTTXD(i)) {
DMA_UNMAP(di->dev, (BUS_SWAP32(R_SM(&di->txd[i].addr)) - di->dataoffset),
(BUS_SWAP32(R_SM(&di->txd[i].ctrl)) & CTRL_BC_MASK), DMA_TX, di->txp[i]);
W_SM(&di->txd[i].addr, 0xdeadbeef);
txp = di->txp[i];
di->txp[i] = NULL;
}
di->txin = i;
/* tx flow control */
di->txavail = di->ntxd - NTXDACTIVE(di->txin, di->txout) - 1;
return (txp);
bogus:
/*
DMA_ERROR(("dma_getnexttxp: bogus curr: start %d end %d txout %d force %d\n",
start, end, di->txout, forceall));
*/
return (NULL);
}
/* like getnexttxp but no reclaim */
void*
dma_peeknexttxp(dma_info_t *di)
{
uint end, i;
end = B2I(R_REG(&di->regs->xmtstatus) & XS_CD_MASK);
for (i = di->txin; i != end; i = NEXTTXD(i))
if (di->txp[i])
return (di->txp[i]);
return (NULL);
}
void
dma_rxreclaim(dma_info_t *di)
{
void *p;
DMA_TRACE(("%s: dma_rxreclaim\n", di->name));
while ((p = dma_getnextrxp(di, TRUE)))
PKTFREE(di->drv, p, FALSE);
}
void *
dma_getnextrxp(dma_info_t *di, bool forceall)
{
uint i;
void *rxp;
/* if forcing, dma engine must be disabled */
ASSERT(!forceall || !dma_rxenabled(di));
i = di->rxin;
/* return if no packets posted */
if (i == di->rxout)
return (NULL);
/* ignore curr if forceall */
if (!forceall && (i == B2I(R_REG(&di->regs->rcvstatus) & RS_CD_MASK)))
return (NULL);
/* get the packet pointer that corresponds to the rx descriptor */
rxp = di->rxp[i];
ASSERT(rxp);
di->rxp[i] = NULL;
/* clear this packet from the descriptor ring */
DMA_UNMAP(di->dev, (BUS_SWAP32(R_SM(&di->rxd[i].addr)) - di->dataoffset),
di->rxbufsize, DMA_RX, rxp);
W_SM(&di->rxd[i].addr, 0xdeadbeef);
di->rxin = NEXTRXD(i);
return (rxp);
}
char*
dma_dumptx(dma_info_t *di, char *buf)
{
buf += sprintf(buf, "txd 0x%lx txdpa 0x%lx txp 0x%lx txin %d txout %d txavail %d\n",
(ulong)di->txd, di->txdpa, (ulong)di->txp, di->txin, di->txout, di->txavail);
buf += sprintf(buf, "xmtcontrol 0x%x xmtaddr 0x%x xmtptr 0x%x xmtstatus 0x%x\n",
R_REG(&di->regs->xmtcontrol),
R_REG(&di->regs->xmtaddr),
R_REG(&di->regs->xmtptr),
R_REG(&di->regs->xmtstatus));
return (buf);
}
char*
dma_dumprx(dma_info_t *di, char *buf)
{
buf += sprintf(buf, "rxd 0x%lx rxdpa 0x%lx rxp 0x%lx rxin %d rxout %d\n",
(ulong)di->rxd, di->rxdpa, (ulong)di->rxp, di->rxin, di->rxout);
buf += sprintf(buf, "rcvcontrol 0x%x rcvaddr 0x%x rcvptr 0x%x rcvstatus 0x%x\n",
R_REG(&di->regs->rcvcontrol),
R_REG(&di->regs->rcvaddr),
R_REG(&di->regs->rcvptr),
R_REG(&di->regs->rcvstatus));
return (buf);
}
char*
dma_dump(dma_info_t *di, char *buf)
{
buf = dma_dumptx(di, buf);
buf = dma_dumprx(di, buf);
return (buf);
}
uint
dma_getvar(dma_info_t *di, char *name)
{
if (!strcmp(name, "&txavail"))
return ((uint) &di->txavail);
else {
ASSERT(0);
}
return (0);
}
void
dma_txblock(dma_info_t *di)
{
di->txavail = 0;
}
void
dma_txunblock(dma_info_t *di)
{
di->txavail = di->ntxd - NTXDACTIVE(di->txin, di->txout) - 1;
}
uint
dma_txactive(dma_info_t *di)
{
return (NTXDACTIVE(di->txin, di->txout));
}
/*
* Rotate all active tx dma ring entries "forward" by (ActiveDescriptor - txin).
*/
void
dma_txrotate(di_t *di)
{
uint ad;
uint nactive;
uint rot;
uint old, new;
uint32 w;
uint first, last;
ASSERT(dma_txsuspended(di));
nactive = dma_txactive(di);
ad = B2I((R_REG(&di->regs->xmtstatus) & XS_AD_MASK) >> XS_AD_SHIFT);
rot = TXD(ad - di->txin);
ASSERT(rot < di->ntxd);
/* full-ring case is a lot harder - don't worry about this */
if (rot >= (di->ntxd - nactive)) {
DMA_ERROR(("%s: dma_txrotate: ring full - punt\n", di->name));
return;
}
first = di->txin;
last = PREVTXD(di->txout);
/* move entries starting at last and moving backwards to first */
for (old = last; old != PREVTXD(first); old = PREVTXD(old)) {
new = TXD(old + rot);
/*
* Move the tx dma descriptor.
* EOT is set only in the last entry in the ring.
*/
w = R_SM(&di->txd[old].ctrl) & ~CTRL_EOT;
if (new == (di->ntxd - 1))
w |= CTRL_EOT;
W_SM(&di->txd[new].ctrl, w);
W_SM(&di->txd[new].addr, R_SM(&di->txd[old].addr));
/* zap the old tx dma descriptor address field */
W_SM(&di->txd[old].addr, 0xdeadbeef);
/* move the corresponding txp[] entry */
ASSERT(di->txp[new] == NULL);
di->txp[new] = di->txp[old];
di->txp[old] = NULL;
}
/* update txin and txout */
di->txin = ad;
di->txout = TXD(di->txout + rot);
di->txavail = di->ntxd - NTXDACTIVE(di->txin, di->txout) - 1;
/* kick the chip */
W_REG(&di->regs->xmtptr, I2B(di->txout));
}