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mmc_spi: support for non-byte-aligned cards
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A very large subset of SD cards in the market send their
responses and data non-byte-aligned. So add logic to the
mmc spi driver to handle this mess.

Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>
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Wolfgang Muees authored and Pierre Ossman committed Apr 8, 2009
1 parent a8fe29d commit ab5a643
Showing 1 changed file with 112 additions and 38 deletions.
150 changes: 112 additions & 38 deletions drivers/mmc/host/mmc_spi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -254,6 +254,10 @@ static int mmc_spi_response_get(struct mmc_spi_host *host,
u8 *cp = host->data->status;
u8 *end = cp + host->t.len;
int value = 0;
int bitshift;
u8 leftover = 0;
unsigned short rotator;
int i;
char tag[32];

snprintf(tag, sizeof(tag), " ... CMD%d response SPI_%s",
Expand All @@ -271,9 +275,8 @@ static int mmc_spi_response_get(struct mmc_spi_host *host,

/* Data block reads (R1 response types) may need more data... */
if (cp == end) {
unsigned i;

cp = host->data->status;
end = cp+1;

/* Card sends N(CR) (== 1..8) bytes of all-ones then one
* status byte ... and we already scanned 2 bytes.
Expand All @@ -298,20 +301,34 @@ static int mmc_spi_response_get(struct mmc_spi_host *host,
}

checkstatus:
if (*cp & 0x80) {
dev_dbg(&host->spi->dev, "%s: INVALID RESPONSE, %02x\n",
tag, *cp);
value = -EBADR;
goto done;
bitshift = 0;
if (*cp & 0x80) {
/* Houston, we have an ugly card with a bit-shifted response */
rotator = *cp++ << 8;
/* read the next byte */
if (cp == end) {
value = mmc_spi_readbytes(host, 1);
if (value < 0)
goto done;
cp = host->data->status;
end = cp+1;
}
rotator |= *cp++;
while (rotator & 0x8000) {
bitshift++;
rotator <<= 1;
}
cmd->resp[0] = rotator >> 8;
leftover = rotator;
} else {
cmd->resp[0] = *cp++;
}

cmd->resp[0] = *cp++;
cmd->error = 0;

/* Status byte: the entire seven-bit R1 response. */
if (cmd->resp[0] != 0) {
if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS
| R1_SPI_ILLEGAL_COMMAND)
| R1_SPI_ILLEGAL_COMMAND)
& cmd->resp[0])
value = -EINVAL;
else if (R1_SPI_COM_CRC & cmd->resp[0])
Expand Down Expand Up @@ -339,12 +356,45 @@ static int mmc_spi_response_get(struct mmc_spi_host *host,
* SPI R5 == R1 + data byte; IO_RW_DIRECT
*/
case MMC_RSP_SPI_R2:
cmd->resp[0] |= *cp << 8;
/* read the next byte */
if (cp == end) {
value = mmc_spi_readbytes(host, 1);
if (value < 0)
goto done;
cp = host->data->status;
end = cp+1;
}
if (bitshift) {
rotator = leftover << 8;
rotator |= *cp << bitshift;
cmd->resp[0] |= (rotator & 0xFF00);
} else {
cmd->resp[0] |= *cp << 8;
}
break;

/* SPI R3, R4, or R7 == R1 + 4 bytes */
case MMC_RSP_SPI_R3:
cmd->resp[1] = get_unaligned_be32(cp);
rotator = leftover << 8;
cmd->resp[1] = 0;
for (i = 0; i < 4; i++) {
cmd->resp[1] <<= 8;
/* read the next byte */
if (cp == end) {
value = mmc_spi_readbytes(host, 1);
if (value < 0)
goto done;
cp = host->data->status;
end = cp+1;
}
if (bitshift) {
rotator |= *cp++ << bitshift;
cmd->resp[1] |= (rotator >> 8);
rotator <<= 8;
} else {
cmd->resp[1] |= *cp++;
}
}
break;

/* SPI R1 == just one status byte */
Expand Down Expand Up @@ -725,6 +775,8 @@ mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,
struct spi_device *spi = host->spi;
int status;
struct scratch *scratch = host->data;
unsigned int bitshift;
u8 leftover;

/* At least one SD card sends an all-zeroes byte when N(CX)
* applies, before the all-ones bytes ... just cope with that.
Expand All @@ -736,38 +788,60 @@ mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,
if (status == 0xff || status == 0)
status = mmc_spi_readtoken(host, timeout);

if (status == SPI_TOKEN_SINGLE) {
if (host->dma_dev) {
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
dma_sync_single_for_device(host->dma_dev,
t->rx_dma, t->len,
DMA_FROM_DEVICE);
}
if (status < 0) {
dev_dbg(&spi->dev, "read error %02x (%d)\n", status, status);
return status;
}

status = spi_sync(spi, &host->m);
/* The token may be bit-shifted...
* the first 0-bit precedes the data stream.
*/
bitshift = 7;
while (status & 0x80) {
status <<= 1;
bitshift--;
}
leftover = status << 1;

if (host->dma_dev) {
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
dma_sync_single_for_cpu(host->dma_dev,
t->rx_dma, t->len,
DMA_FROM_DEVICE);
}
if (host->dma_dev) {
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
dma_sync_single_for_device(host->dma_dev,
t->rx_dma, t->len,
DMA_FROM_DEVICE);
}

} else {
dev_dbg(&spi->dev, "read error %02x (%d)\n", status, status);
status = spi_sync(spi, &host->m);

/* we've read extra garbage, timed out, etc */
if (status < 0)
return status;
if (host->dma_dev) {
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
dma_sync_single_for_cpu(host->dma_dev,
t->rx_dma, t->len,
DMA_FROM_DEVICE);
}

/* low four bits are an R2 subset, fifth seems to be
* vendor specific ... map them all to generic error..
if (bitshift) {
/* Walk through the data and the crc and do
* all the magic to get byte-aligned data.
*/
return -EIO;
u8 *cp = t->rx_buf;
unsigned int len;
unsigned int bitright = 8 - bitshift;
u8 temp;
for (len = t->len; len; len--) {
temp = *cp;
*cp++ = leftover | (temp >> bitshift);
leftover = temp << bitright;
}
cp = (u8 *) &scratch->crc_val;
temp = *cp;
*cp++ = leftover | (temp >> bitshift);
leftover = temp << bitright;
temp = *cp;
*cp = leftover | (temp >> bitshift);
}

if (host->mmc->use_spi_crc) {
Expand Down

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