- 根目录:
- drivers
- mmc
- host
- mmc_spi.c
/*
* mmc_spi.c - Access SD/MMC cards through SPI master controllers
*
* (C) Copyright 2005, Intec Automation,
* Mike Lavender (mike@steroidmicros)
* (C) Copyright 2006-2007, David Brownell
* (C) Copyright 2007, Axis Communications,
* Hans-Peter Nilsson (hp@axis.com)
* (C) Copyright 2007, ATRON electronic GmbH,
* Jan Nikitenko <jan.nikitenko@gmail.com>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/dma-mapping.h>
#include <linux/crc7.h>
#include <linux/crc-itu-t.h>
#include <linux/scatterlist.h>
#include <linux/mmc/host.h>
#include <linux/mmc/mmc.h> /* for R1_SPI_* bit values */
#include <linux/mmc/slot-gpio.h>
#include <linux/spi/spi.h>
#include <linux/spi/mmc_spi.h>
#include <asm/unaligned.h>
/* NOTES:
*
* - For now, we won't try to interoperate with a real mmc/sd/sdio
* controller, although some of them do have hardware support for
* SPI protocol. The main reason for such configs would be mmc-ish
* cards like DataFlash, which don't support that "native" protocol.
*
* We don't have a "DataFlash/MMC/SD/SDIO card slot" abstraction to
* switch between driver stacks, and in any case if "native" mode
* is available, it will be faster and hence preferable.
*
* - MMC depends on a different chipselect management policy than the
* SPI interface currently supports for shared bus segments: it needs
* to issue multiple spi_message requests with the chipselect active,
* using the results of one message to decide the next one to issue.
*
* Pending updates to the programming interface, this driver expects
* that it not share the bus with other drivers (precluding conflicts).
*
* - We tell the controller to keep the chipselect active from the
* beginning of an mmc_host_ops.request until the end. So beware
* of SPI controller drivers that mis-handle the cs_change flag!
*
* However, many cards seem OK with chipselect flapping up/down
* during that time ... at least on unshared bus segments.
*/
/*
* Local protocol constants, internal to data block protocols.
*/
/* Response tokens used to ack each block written: */
#define SPI_MMC_RESPONSE_CODE(x) ((x) & 0x1f)
#define SPI_RESPONSE_ACCEPTED ((2 << 1)|1)
#define SPI_RESPONSE_CRC_ERR ((5 << 1)|1)
#define SPI_RESPONSE_WRITE_ERR ((6 << 1)|1)
/* Read and write blocks start with these tokens and end with crc;
* on error, read tokens act like a subset of R2_SPI_* values.
*/
#define SPI_TOKEN_SINGLE 0xfe /* single block r/w, multiblock read */
#define SPI_TOKEN_MULTI_WRITE 0xfc /* multiblock write */
#define SPI_TOKEN_STOP_TRAN 0xfd /* terminate multiblock write */
#define MMC_SPI_BLOCKSIZE 512
/* These fixed timeouts come from the latest SD specs, which say to ignore
* the CSD values. The R1B value is for card erase (e.g. the "I forgot the
* card's password" scenario); it's mostly applied to STOP_TRANSMISSION after
* reads which takes nowhere near that long. Older cards may be able to use
* shorter timeouts ... but why bother?
*/
#define r1b_timeout (HZ * 3)
/* One of the critical speed parameters is the amount of data which may
* be transferred in one command. If this value is too low, the SD card
* controller has to do multiple partial block writes (argggh!). With
* today (2008) SD cards there is little speed gain if we transfer more
* than 64 KBytes at a time. So use this value until there is any indication
* that we should do more here.
*/
#define MMC_SPI_BLOCKSATONCE 128
/****************************************************************************/
/*
* Local Data Structures
*/
/* "scratch" is per-{command,block} data exchanged with the card */
struct scratch {
u8 status[29];
u8 data_token;
__be16 crc_val;
};
struct mmc_spi_host {
struct mmc_host *mmc;
struct spi_device *spi;
unsigned char power_mode;
u16 powerup_msecs;
struct mmc_spi_platform_data *pdata;
/* for bulk data transfers */
struct spi_transfer token, t, crc, early_status;
struct spi_message m;
/* for status readback */
struct spi_transfer status;
struct spi_message readback;
/* underlying DMA-aware controller, or null */
struct device *dma_dev;
/* buffer used for commands and for message "overhead" */
struct scratch *data;
dma_addr_t data_dma;
/* Specs say to write ones most of the time, even when the card
* has no need to read its input data; and many cards won't care.
* This is our source of those ones.
*/
void *ones;
dma_addr_t ones_dma;
};
/****************************************************************************/
/*
* MMC-over-SPI protocol glue, used by the MMC stack interface
*/
static inline int mmc_cs_off(struct mmc_spi_host *host)
{
/* chipselect will always be inactive after setup() */
return spi_setup(host->spi);
}
static int
mmc_spi_readbytes(struct mmc_spi_host *host, unsigned len)
{
int status;
if (len > sizeof(*host->data)) {
WARN_ON(1);
return -EIO;
}
host->status.len = len;
if (host->dma_dev)
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*host->data),
DMA_FROM_DEVICE);
status = spi_sync_locked(host->spi, &host->readback);
if (host->dma_dev)
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*host->data),
DMA_FROM_DEVICE);
return status;
}
static int mmc_spi_skip(struct mmc_spi_host *host, unsigned long timeout,
unsigned n, u8 byte)
{
u8 *cp = host->data->status;
unsigned long start = jiffies;
while (1) {
int status;
unsigned i;
status = mmc_spi_readbytes(host, n);
if (status < 0)
return status;
for (i = 0; i < n; i++) {
if (cp[i] != byte)
return cp[i];
}
if (time_is_before_jiffies(start + timeout))
break;
/* If we need long timeouts, we may release the CPU.
* We use jiffies here because we want to have a relation
* between elapsed time and the blocking of the scheduler.
*/
if (time_is_before_jiffies(start+1))
schedule();
}
return -ETIMEDOUT;
}
static inline int
mmc_spi_wait_unbusy(struct mmc_spi_host *host, unsigned long timeout)
{
return mmc_spi_skip(host, timeout, sizeof(host->data->status), 0);
}
static int mmc_spi_readtoken(struct mmc_spi_host *host, unsigned long timeout)
{
return mmc_spi_skip(host, timeout, 1, 0xff);
}
/*
* Note that for SPI, cmd->resp[0] is not the same data as "native" protocol
* hosts return! The low byte holds R1_SPI bits. The next byte may hold
* R2_SPI bits ... for SEND_STATUS, or after data read errors.
*
* cmd->resp[1] holds any four-byte response, for R3 (READ_OCR) and on
* newer cards R7 (IF_COND).
*/
static char *maptype(struct mmc_command *cmd)
{
switch (mmc_spi_resp_type(cmd)) {
case MMC_RSP_SPI_R1: return "R1";
case MMC_RSP_SPI_R1B: return "R1B";
case MMC_RSP_SPI_R2: return "R2/R5";
case MMC_RSP_SPI_R3: return "R3/R4/R7";
default: return "?";
}
}
/* return zero, else negative errno after setting cmd->error */
static int mmc_spi_response_get(struct mmc_spi_host *host,
struct mmc_command *cmd, int cs_on)
{
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",
cmd->opcode, maptype(cmd));
/* Except for data block reads, the whole response will already
* be stored in the scratch buffer. It's somewhere after the
* command and the first byte we read after it. We ignore that
* first byte. After STOP_TRANSMISSION command it may include
* two data bits, but otherwise it's all ones.
*/
cp += 8;
while (cp < end && *cp == 0xff)
cp++;
/* Data block reads (R1 response types) may need more data... */
if (cp == end) {
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.
*
* REVISIT block read paths use nasty byte-at-a-time I/O
* so it can always DMA directly into the target buffer.
* It'd probably be better to memcpy() the first chunk and
* avoid extra i/o calls...
*
* Note we check for more than 8 bytes, because in practice,
* some SD cards are slow...
*/
for (i = 2; i < 16; i++) {
value = mmc_spi_readbytes(host, 1);
if (value < 0)
goto done;
if (*cp != 0xff)
goto checkstatus;
}
value = -ETIMEDOUT;
goto done;
}
checkstatus:
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->error = 0;
/* Status byte: the entire seven-bit R1 response. */
if (cmd->resp[0] != 0) {
if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS)
& cmd->resp[0])
value = -EFAULT; /* Bad address */
else if (R1_SPI_ILLEGAL_COMMAND & cmd->resp[0])
value = -ENOSYS; /* Function not implemented */
else if (R1_SPI_COM_CRC & cmd->resp[0])
value = -EILSEQ; /* Illegal byte sequence */
else if ((R1_SPI_ERASE_SEQ | R1_SPI_ERASE_RESET)
& cmd->resp[0])
value = -EIO; /* I/O error */
/* else R1_SPI_IDLE, "it's resetting" */
}
switch (mmc_spi_resp_type(cmd)) {
/* SPI R1B == R1 + busy; STOP_TRANSMISSION (for multiblock reads)
* and less-common stuff like various erase operations.
*/
case MMC_RSP_SPI_R1B:
/* maybe we read all the busy tokens already */
while (cp < end && *cp == 0)
cp++;
if (cp == end)
mmc_spi_wait_unbusy(host, r1b_timeout);
break;
/* SPI R2 == R1 + second status byte; SEND_STATUS
* SPI R5 == R1 + data byte; IO_RW_DIRECT
*/
case MMC_RSP_SPI_R2:
/* 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:
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 */
case MMC_RSP_SPI_R1:
break;
default:
dev_dbg(&host->spi->dev, "bad response type %04x\n",
mmc_spi_resp_type(cmd));
if (value >= 0)
value = -EINVAL;
goto done;
}
if (value < 0)
dev_dbg(&host->spi->dev, "%s: resp %04x %08x\n",
tag, cmd->resp[0], cmd->resp[1]);
/* disable chipselect on errors and some success cases */
if (value >= 0 && cs_on)
return value;
done:
if (value < 0)
cmd->error = value;
mmc_cs_off(host);
return value;
}
/* Issue command and read its response.
* Returns zero on success, negative for error.
*
* On error, caller must cope with mmc core retry mechanism. That
* means immediate low-level resubmit, which affects the bus lock...
*/
static int
mmc_spi_command_send(struct mmc_spi_host *host,
struct mmc_request *mrq,
struct mmc_command *cmd, int cs_on)
{
struct scratch *data = host->data;
u8 *cp = data->status;
u32 arg = cmd->arg;
int status;
struct spi_transfer *t;
/* We can handle most commands (except block reads) in one full
* duplex I/O operation before either starting the next transfer
* (data block or command) or else deselecting the card.
*
* First, write 7 bytes:
* - an all-ones byte to ensure the card is ready
* - opcode byte (plus start and transmission bits)
* - four bytes of big-endian argument
* - crc7 (plus end bit) ... always computed, it's cheap
*
* We init the whole buffer to all-ones, which is what we need
* to write while we're reading (later) response data.
*/
memset(cp++, 0xff, sizeof(data->status));
*cp++ = 0x40 | cmd->opcode;
*cp++ = (u8)(arg >> 24);
*cp++ = (u8)(arg >> 16);
*cp++ = (u8)(arg >> 8);
*cp++ = (u8)arg;
*cp++ = (crc7(0, &data->status[1], 5) << 1) | 0x01;
/* Then, read up to 13 bytes (while writing all-ones):
* - N(CR) (== 1..8) bytes of all-ones
* - status byte (for all response types)
* - the rest of the response, either:
* + nothing, for R1 or R1B responses
* + second status byte, for R2 responses
* + four data bytes, for R3 and R7 responses
*
* Finally, read some more bytes ... in the nice cases we know in
* advance how many, and reading 1 more is always OK:
* - N(EC) (== 0..N) bytes of all-ones, before deselect/finish
* - N(RC) (== 1..N) bytes of all-ones, before next command
* - N(WR) (== 1..N) bytes of all-ones, before data write
*
* So in those cases one full duplex I/O of at most 21 bytes will
* handle the whole command, leaving the card ready to receive a
* data block or new command. We do that whenever we can, shaving
* CPU and IRQ costs (especially when using DMA or FIFOs).
*
* There are two other cases, where it's not generally practical
* to rely on a single I/O:
*
* - R1B responses need at least N(EC) bytes of all-zeroes.
*
* In this case we can *try* to fit it into one I/O, then
* maybe read more data later.
*
* - Data block reads are more troublesome, since a variable
* number of padding bytes precede the token and data.
* + N(CX) (== 0..8) bytes of all-ones, before CSD or CID
* + N(AC) (== 1..many) bytes of all-ones
*
* In this case we currently only have minimal speedups here:
* when N(CR) == 1 we can avoid I/O in response_get().
*/
if (cs_on && (mrq->data->flags & MMC_DATA_READ)) {
cp += 2; /* min(N(CR)) + status */
/* R1 */
} else {
cp += 10; /* max(N(CR)) + status + min(N(RC),N(WR)) */
if (cmd->flags & MMC_RSP_SPI_S2) /* R2/R5 */
cp++;
else if (cmd->flags & MMC_RSP_SPI_B4) /* R3/R4/R7 */
cp += 4;
else if (cmd->flags & MMC_RSP_BUSY) /* R1B */
cp = data->status + sizeof(data->status);
/* else: R1 (most commands) */
}
dev_dbg(&host->spi->dev, " mmc_spi: CMD%d, resp %s\n",
cmd->opcode, maptype(cmd));
/* send command, leaving chipselect active */
spi_message_init(&host->m);
t = &host->t;
memset(t, 0, sizeof(*t));
t->tx_buf = t->rx_buf = data->status;
t->tx_dma = t->rx_dma = host->data_dma;
t->len = cp - data->status;
t->cs_change = 1;
spi_message_add_tail(t, &host->m);
if (host->dma_dev) {
host->m.is_dma_mapped = 1;
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*host->data),
DMA_BIDIRECTIONAL);
}
status = spi_sync_locked(host->spi, &host->m);
if (host->dma_dev)
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*host->data),
DMA_BIDIRECTIONAL);
if (status < 0) {
dev_dbg(&host->spi->dev, " ... write returned %d\n", status);
cmd->error = status;
return status;
}
/* after no-data commands and STOP_TRANSMISSION, chipselect off */
return mmc_spi_response_get(host, cmd, cs_on);
}
/* Build data message with up to four separate transfers. For TX, we
* start by writing the data token. And in most cases, we finish with
* a status transfer.
*
* We always provide TX data for data and CRC. The MMC/SD protocol
* requires us to write ones; but Linux defaults to writing zeroes;
* so we explicitly initialize it to all ones on RX paths.
*
* We also handle DMA mapping, so the underlying SPI controller does
* not need to (re)do it for each message.
*/
static void
mmc_spi_setup_data_message(
struct mmc_spi_host *host,
int multiple,
enum dma_data_direction direction)
{
struct spi_transfer *t;
struct scratch *scratch = host->data;
dma_addr_t dma = host->data_dma;
spi_message_init(&host->m);
if (dma)
host->m.is_dma_mapped = 1;
/* for reads, readblock() skips 0xff bytes before finding
* the token; for writes, this transfer issues that token.
*/
if (direction == DMA_TO_DEVICE) {
t = &host->token;
memset(t, 0, sizeof(*t));
t->len = 1;
if (multiple)
scratch->data_token = SPI_TOKEN_MULTI_WRITE;
else
scratch->data_token = SPI_TOKEN_SINGLE;
t->tx_buf = &scratch->data_token;
if (dma)
t->tx_dma = dma + offsetof(struct scratch, data_token);
spi_message_add_tail(t, &host->m);
}
/* Body of transfer is buffer, then CRC ...
* either TX-only, or RX with TX-ones.
*/
t = &host->t;
memset(t, 0, sizeof(*t));
t->tx_buf = host->ones;
t->tx_dma = host->ones_dma;
/* length and actual buffer info are written later */
spi_message_add_tail(t, &host->m);
t = &host->crc;
memset(t, 0, sizeof(*t));
t->len = 2;
if (direction == DMA_TO_DEVICE) {
/* the actual CRC may get written later */
t->tx_buf = &scratch->crc_val;
if (dma)
t->tx_dma = dma + offsetof(struct scratch, crc_val);
} else {
t->tx_buf = host->ones;
t->tx_dma = host->ones_dma;
t->rx_buf = &scratch->crc_val;
if (dma)
t->rx_dma = dma + offsetof(struct scratch, crc_val);
}
spi_message_add_tail(t, &host->m);
/*
* A single block read is followed by N(EC) [0+] all-ones bytes
* before deselect ... don't bother.
*
* Multiblock reads are followed by N(AC) [1+] all-ones bytes before
* the next block is read, or a STOP_TRANSMISSION is issued. We'll
* collect that single byte, so readblock() doesn't need to.
*
* For a write, the one-byte data response follows immediately, then
* come zero or more busy bytes, then N(WR) [1+] all-ones bytes.
* Then single block reads may deselect, and multiblock ones issue
* the next token (next data block, or STOP_TRAN). We can try to
* minimize I/O ops by using a single read to collect end-of-busy.
*/
if (multiple || direction == DMA_TO_DEVICE) {
t = &host->early_status;
memset(t, 0, sizeof(*t));
t->len = (direction == DMA_TO_DEVICE)
? sizeof(scratch->status)
: 1;
t->tx_buf = host->ones;
t->tx_dma = host->ones_dma;
t->rx_buf = scratch->status;
if (dma)
t->rx_dma = dma + offsetof(struct scratch, status);
t->cs_change = 1;
spi_message_add_tail(t, &host->m);
}
}
/*
* Write one block:
* - caller handled preceding N(WR) [1+] all-ones bytes
* - data block
* + token
* + data bytes
* + crc16
* - an all-ones byte ... card writes a data-response byte
* - followed by N(EC) [0+] all-ones bytes, card writes zero/'busy'
*
* Return negative errno, else success.
*/
static int
mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
unsigned long timeout)
{
struct spi_device *spi = host->spi;
int status, i;
struct scratch *scratch = host->data;
u32 pattern;
if (host->mmc->use_spi_crc)
scratch->crc_val = cpu_to_be16(
crc_itu_t(0, t->tx_buf, t->len));
if (host->dma_dev)
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
status = spi_sync_locked(spi, &host->m);
if (status != 0) {
dev_dbg(&spi->dev, "write error (%d)\n", status);
return status;
}
if (host->dma_dev)
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
/*
* Get the transmission data-response reply. It must follow
* immediately after the data block we transferred. This reply
* doesn't necessarily tell whether the write operation succeeded;
* it just says if the transmission was ok and whether *earlier*
* writes succeeded; see the standard.
*
* In practice, there are (even modern SDHC-)cards which are late
* in sending the response, and miss the time frame by a few bits,
* so we have to cope with this situation and check the response
* bit-by-bit. Arggh!!!
*/
pattern = scratch->status[0] << 24;
pattern |= scratch->status[1] << 16;
pattern |= scratch->status[2] << 8;
pattern |= scratch->status[3];
/* First 3 bit of pattern are undefined */
pattern |= 0xE0000000;
/* left-adjust to leading 0 bit */
while (pattern & 0x80000000)
pattern <<= 1;
/* right-adjust for pattern matching. Code is in bit 4..0 now. */
pattern >>= 27;
switch (pattern) {
case SPI_RESPONSE_ACCEPTED:
status = 0;
break;
case SPI_RESPONSE_CRC_ERR:
/* host shall then issue MMC_STOP_TRANSMISSION */
status = -EILSEQ;
break;
case SPI_RESPONSE_WRITE_ERR:
/* host shall then issue MMC_STOP_TRANSMISSION,
* and should MMC_SEND_STATUS to sort it out
*/
status = -EIO;
break;
default:
status = -EPROTO;
break;
}
if (status != 0) {
dev_dbg(&spi->dev, "write error %02x (%d)\n",
scratch->status[0], status);
return status;
}
t->tx_buf += t->len;
if (host->dma_dev)
t->tx_dma += t->len;
/* Return when not busy. If we didn't collect that status yet,
* we'll need some more I/O.
*/
for (i = 4; i < sizeof(scratch->status); i++) {
/* card is non-busy if the most recent bit is 1 */
if (scratch->status[i] & 0x01)
return 0;
}
return mmc_spi_wait_unbusy(host, timeout);
}
/*
* Read one block:
* - skip leading all-ones bytes ... either
* + N(AC) [1..f(clock,CSD)] usually, else
* + N(CX) [0..8] when reading CSD or CID
* - data block
* + token ... if error token, no data or crc
* + data bytes
* + crc16
*
* After single block reads, we're done; N(EC) [0+] all-ones bytes follow
* before dropping chipselect.
*
* For multiblock reads, caller either reads the next block or issues a
* STOP_TRANSMISSION command.
*/
static int
mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,
unsigned long timeout)
{
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.
*/
status = mmc_spi_readbytes(host, 1);
if (status < 0)
return status;
status = scratch->status[0];
if (status == 0xff || status == 0)
status = mmc_spi_readtoken(host, timeout);
if (status < 0) {
dev_dbg(&spi->dev, "read error %02x (%d)\n", status, status);
return status;
}
/* 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_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);
}
status = spi_sync_locked(spi, &host->m);
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 (bitshift) {
/* Walk through the data and the crc and do
* all the magic to get byte-aligned data.
*/
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) {
u16 crc = crc_itu_t(0, t->rx_buf, t->len);
be16_to_cpus(&scratch->crc_val);
if (scratch->crc_val != crc) {
dev_dbg(&spi->dev, "read - crc error: crc_val=0x%04x, "
"computed=0x%04x len=%d\n",
scratch->crc_val, crc, t->len);
return -EILSEQ;
}
}
t->rx_buf += t->len;
if (host->dma_dev)
t->rx_dma += t->len;
return 0;
}
/*
* An MMC/SD data stage includes one or more blocks, optional CRCs,
* and inline handshaking. That handhaking makes it unlike most
* other SPI protocol stacks.
*/
static void
mmc_spi_data_do(struct mmc_spi_host *host, struct mmc_command *cmd,
struct mmc_data *data, u32 blk_size)
{
struct spi_device *spi = host->spi;
struct device *dma_dev = host->dma_dev;
struct spi_transfer *t;
enum dma_data_direction direction;
struct scatterlist *sg;
unsigned n_sg;
int multiple = (data->blocks > 1);
u32 clock_rate;
unsigned long timeout;
if (data->flags & MMC_DATA_READ)
direction = DMA_FROM_DEVICE;
else
direction = DMA_TO_DEVICE;
mmc_spi_setup_data_message(host, multiple, direction);
t = &host->t;
if (t->speed_hz)
clock_rate = t->speed_hz;
else
clock_rate = spi->max_speed_hz;
timeout = data->timeout_ns +
data->timeout_clks * 1000000 / clock_rate;
timeout = usecs_to_jiffies((unsigned int)(timeout / 1000)) + 1;
/* Handle scatterlist segments one at a time, with synch for
* each 512-byte block
*/
for (sg = data->sg, n_sg = data->sg_len; n_sg; n_sg--, sg++) {
int status = 0;
dma_addr_t dma_addr = 0;
void *kmap_addr;
unsigned length = sg->length;
enum dma_data_direction dir = direction;
/* set up dma mapping for controller drivers that might
* use DMA ... though they may fall back to PIO
*/
if (dma_dev) {
/* never invalidate whole *shared* pages ... */
if ((sg->offset != 0 || length != PAGE_SIZE)
&& dir == DMA_FROM_DEVICE)
dir = DMA_BIDIRECTIONAL;
dma_addr = dma_map_page(dma_dev, sg_page(sg), 0,
PAGE_SIZE, dir);
if (direction == DMA_TO_DEVICE)
t->tx_dma = dma_addr + sg->offset;
else
t->rx_dma = dma_addr + sg->offset;
}
/* allow pio too; we don't allow highmem */
kmap_addr = kmap(sg_page(sg));
if (direction == DMA_TO_DEVICE)
t->tx_buf = kmap_addr + sg->offset;
else
t->rx_buf = kmap_addr + sg->offset;
/* transfer each block, and update request status */
while (length) {
t->len = min(length, blk_size);
dev_dbg(&host->spi->dev,
" mmc_spi: %s block, %d bytes\n",
(direction == DMA_TO_DEVICE)
? "write"
: "read",
t->len);
if (direction == DMA_TO_DEVICE)
status = mmc_spi_writeblock(host, t, timeout);
else
status = mmc_spi_readblock(host, t, timeout);
if (status < 0)
break;
data->bytes_xfered += t->len;
length -= t->len;
if (!multiple)
break;
}
/* discard mappings */
if (direction == DMA_FROM_DEVICE)
flush_kernel_dcache_page(sg_page(sg));
kunmap(sg_page(sg));
if (dma_dev)
dma_unmap_page(dma_dev, dma_addr, PAGE_SIZE, dir);
if (status < 0) {
data->error = status;
dev_dbg(&spi->dev, "%s status %d\n",
(direction == DMA_TO_DEVICE)
? "write" : "read",
status);
break;
}
}
/* NOTE some docs describe an MMC-only SET_BLOCK_COUNT (CMD23) that
* can be issued before multiblock writes. Unlike its more widely
* documented analogue for SD cards (SET_WR_BLK_ERASE_COUNT, ACMD23),
* that can affect the STOP_TRAN logic. Complete (and current)
* MMC specs should sort that out before Linux starts using CMD23.
*/
if (direction == DMA_TO_DEVICE && multiple) {
struct scratch *scratch = host->data;
int tmp;
const unsigned statlen = sizeof(scratch->status);
dev_dbg(&spi->dev, " mmc_spi: STOP_TRAN\n");
/* Tweak the per-block message we set up earlier by morphing
* it to hold single buffer with the token followed by some
* all-ones bytes ... skip N(BR) (0..1), scan the rest for
* "not busy any longer" status, and leave chip selected.
*/
INIT_LIST_HEAD(&host->m.transfers);
list_add(&host->early_status.transfer_list,
&host->m.transfers);
memset(scratch->status, 0xff, statlen);
scratch->status[0] = SPI_TOKEN_STOP_TRAN;
host->early_status.tx_buf = host->early_status.rx_buf;
host->early_status.tx_dma = host->early_status.rx_dma;
host->early_status.len = statlen;
if (host->dma_dev)
dma_sync_single_for_device(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
tmp = spi_sync_locked(spi, &host->m);
if (host->dma_dev)
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*scratch),
DMA_BIDIRECTIONAL);
if (tmp < 0) {
if (!data->error)
data->error = tmp;
return;
}
/* Ideally we collected "not busy" status with one I/O,
* avoiding wasteful byte-at-a-time scanning... but more
* I/O is often needed.
*/
for (tmp = 2; tmp < statlen; tmp++) {
if (scratch->status[tmp] != 0)
return;
}
tmp = mmc_spi_wait_unbusy(host, timeout);
if (tmp < 0 && !data->error)
data->error = tmp;
}
}
/****************************************************************************/
/*
* MMC driver implementation -- the interface to the MMC stack
*/
static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
struct mmc_spi_host *host = mmc_priv(mmc);
int status = -EINVAL;
int crc_retry = 5;
struct mmc_command stop;
#ifdef DEBUG
/* MMC core and layered drivers *MUST* issue SPI-aware commands */
{
struct mmc_command *cmd;
int invalid = 0;
cmd = mrq->cmd;
if (!mmc_spi_resp_type(cmd)) {
dev_dbg(&host->spi->dev, "bogus command\n");
cmd->error = -EINVAL;
invalid = 1;
}
cmd = mrq->stop;
if (cmd && !mmc_spi_resp_type(cmd)) {
dev_dbg(&host->spi->dev, "bogus STOP command\n");
cmd->error = -EINVAL;
invalid = 1;
}
if (invalid) {
dump_stack();
mmc_request_done(host->mmc, mrq);
return;
}
}
#endif
/* request exclusive bus access */
spi_bus_lock(host->spi->master);
crc_recover:
/* issue command; then optionally data and stop */
status = mmc_spi_command_send(host, mrq, mrq->cmd, mrq->data != NULL);
if (status == 0 && mrq->data) {
mmc_spi_data_do(host, mrq->cmd, mrq->data, mrq->data->blksz);
/*
* The SPI bus is not always reliable for large data transfers.
* If an occasional crc error is reported by the SD device with
* data read/write over SPI, it may be recovered by repeating
* the last SD command again. The retry count is set to 5 to
* ensure the driver passes stress tests.
*/
if (mrq->data->error == -EILSEQ && crc_retry) {
stop.opcode = MMC_STOP_TRANSMISSION;
stop.arg = 0;
stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
status = mmc_spi_command_send(host, mrq, &stop, 0);
crc_retry--;
mrq->data->error = 0;
goto crc_recover;
}
if (mrq->stop)
status = mmc_spi_command_send(host, mrq, mrq->stop, 0);
else
mmc_cs_off(host);
}
/* release the bus */
spi_bus_unlock(host->spi->master);
mmc_request_done(host->mmc, mrq);
}
/* See Section 6.4.1, in SD "Simplified Physical Layer Specification 2.0"
*
* NOTE that here we can't know that the card has just been powered up;
* not all MMC/SD sockets support power switching.
*
* FIXME when the card is still in SPI mode, e.g. from a previous kernel,
* this doesn't seem to do the right thing at all...
*/
static void mmc_spi_initsequence(struct mmc_spi_host *host)
{
/* Try to be very sure any previous command has completed;
* wait till not-busy, skip debris from any old commands.
*/
mmc_spi_wait_unbusy(host, r1b_timeout);
mmc_spi_readbytes(host, 10);
/*
* Do a burst with chipselect active-high. We need to do this to
* meet the requirement of 74 clock cycles with both chipselect
* and CMD (MOSI) high before CMD0 ... after the card has been
* powered up to Vdd(min), and so is ready to take commands.
*
* Some cards are particularly needy of this (e.g. Viking "SD256")
* while most others don't seem to care.
*
* Note that this is one of the places MMC/SD plays games with the
* SPI protocol. Another is that when chipselect is released while
* the card returns BUSY status, the clock must issue several cycles
* with chipselect high before the card will stop driving its output.
*/
host->spi->mode |= SPI_CS_HIGH;
if (spi_setup(host->spi) != 0) {
/* Just warn; most cards work without it. */
dev_warn(&host->spi->dev,
"can't change chip-select polarity\n");
host->spi->mode &= ~SPI_CS_HIGH;
} else {
mmc_spi_readbytes(host, 18);
host->spi->mode &= ~SPI_CS_HIGH;
if (spi_setup(host->spi) != 0) {
/* Wot, we can't get the same setup we had before? */
dev_err(&host->spi->dev,
"can't restore chip-select polarity\n");
}
}
}
static char *mmc_powerstring(u8 power_mode)
{
switch (power_mode) {
case MMC_POWER_OFF: return "off";
case MMC_POWER_UP: return "up";
case MMC_POWER_ON: return "on";
}
return "?";
}
static void mmc_spi_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
struct mmc_spi_host *host = mmc_priv(mmc);
if (host->power_mode != ios->power_mode) {
int canpower;
canpower = host->pdata && host->pdata->setpower;
dev_dbg(&host->spi->dev, "mmc_spi: power %s (%d)%s\n",
mmc_powerstring(ios->power_mode),
ios->vdd,
canpower ? ", can switch" : "");
/* switch power on/off if possible, accounting for
* max 250msec powerup time if needed.
*/
if (canpower) {
switch (ios->power_mode) {
case MMC_POWER_OFF:
case MMC_POWER_UP:
host->pdata->setpower(&host->spi->dev,
ios->vdd);
if (ios->power_mode == MMC_POWER_UP)
msleep(host->powerup_msecs);
}
}
/* See 6.4.1 in the simplified SD card physical spec 2.0 */
if (ios->power_mode == MMC_POWER_ON)
mmc_spi_initsequence(host);
/* If powering down, ground all card inputs to avoid power
* delivery from data lines! On a shared SPI bus, this
* will probably be temporary; 6.4.2 of the simplified SD
* spec says this must last at least 1msec.
*
* - Clock low means CPOL 0, e.g. mode 0
* - MOSI low comes from writing zero
* - Chipselect is usually active low...
*/
if (canpower && ios->power_mode == MMC_POWER_OFF) {
int mres;
u8 nullbyte = 0;
host->spi->mode &= ~(SPI_CPOL|SPI_CPHA);
mres = spi_setup(host->spi);
if (mres < 0)
dev_dbg(&host->spi->dev,
"switch to SPI mode 0 failed\n");
if (spi_write(host->spi, &nullbyte, 1) < 0)
dev_dbg(&host->spi->dev,
"put spi signals to low failed\n");
/*
* Now clock should be low due to spi mode 0;
* MOSI should be low because of written 0x00;
* chipselect should be low (it is active low)
* power supply is off, so now MMC is off too!
*
* FIXME no, chipselect can be high since the
* device is inactive and SPI_CS_HIGH is clear...
*/
msleep(10);
if (mres == 0) {
host->spi->mode |= (SPI_CPOL|SPI_CPHA);
mres = spi_setup(host->spi);
if (mres < 0)
dev_dbg(&host->spi->dev,
"switch back to SPI mode 3"
" failed\n");
}
}
host->power_mode = ios->power_mode;
}
if (host->spi->max_speed_hz != ios->clock && ios->clock != 0) {
int status;
host->spi->max_speed_hz = ios->clock;
status = spi_setup(host->spi);
dev_dbg(&host->spi->dev,
"mmc_spi: clock to %d Hz, %d\n",
host->spi->max_speed_hz, status);
}
}
static const struct mmc_host_ops mmc_spi_ops = {
.request = mmc_spi_request,
.set_ios = mmc_spi_set_ios,
.get_ro = mmc_gpio_get_ro,
.get_cd = mmc_gpio_get_cd,
};
/****************************************************************************/
/*
* SPI driver implementation
*/
static irqreturn_t
mmc_spi_detect_irq(int irq, void *mmc)
{
struct mmc_spi_host *host = mmc_priv(mmc);
u16 delay_msec = max(host->pdata->detect_delay, (u16)100);
mmc_detect_change(mmc, msecs_to_jiffies(delay_msec));
return IRQ_HANDLED;
}
static int mmc_spi_probe(struct spi_device *spi)
{
void *ones;
struct mmc_host *mmc;
struct mmc_spi_host *host;
int status;
bool has_ro = false;
/* We rely on full duplex transfers, mostly to reduce
* per-transfer overheads (by making fewer transfers).
*/
if (spi->master->flags & SPI_MASTER_HALF_DUPLEX)
return -EINVAL;
/* MMC and SD specs only seem to care that sampling is on the
* rising edge ... meaning SPI modes 0 or 3. So either SPI mode
* should be legit. We'll use mode 0 since the steady state is 0,
* which is appropriate for hotplugging, unless the platform data
* specify mode 3 (if hardware is not compatible to mode 0).
*/
if (spi->mode != SPI_MODE_3)
spi->mode = SPI_MODE_0;
spi->bits_per_word = 8;
status = spi_setup(spi);
if (status < 0) {
dev_dbg(&spi->dev, "needs SPI mode %02x, %d KHz; %d\n",
spi->mode, spi->max_speed_hz / 1000,
status);
return status;
}
/* We need a supply of ones to transmit. This is the only time
* the CPU touches these, so cache coherency isn't a concern.
*
* NOTE if many systems use more than one MMC-over-SPI connector
* it'd save some memory to share this. That's evidently rare.
*/
status = -ENOMEM;
ones = kmalloc(MMC_SPI_BLOCKSIZE, GFP_KERNEL);
if (!ones)
goto nomem;
memset(ones, 0xff, MMC_SPI_BLOCKSIZE);
mmc = mmc_alloc_host(sizeof(*host), &spi->dev);
if (!mmc)
goto nomem;
mmc->ops = &mmc_spi_ops;
mmc->max_blk_size = MMC_SPI_BLOCKSIZE;
mmc->max_segs = MMC_SPI_BLOCKSATONCE;
mmc->max_req_size = MMC_SPI_BLOCKSATONCE * MMC_SPI_BLOCKSIZE;
mmc->max_blk_count = MMC_SPI_BLOCKSATONCE;
mmc->caps = MMC_CAP_SPI;
/* SPI doesn't need the lowspeed device identification thing for
* MMC or SD cards, since it never comes up in open drain mode.
* That's good; some SPI masters can't handle very low speeds!
*
* However, low speed SDIO cards need not handle over 400 KHz;
* that's the only reason not to use a few MHz for f_min (until
* the upper layer reads the target frequency from the CSD).
*/
mmc->f_min = 400000;
mmc->f_max = spi->max_speed_hz;
host = mmc_priv(mmc);
host->mmc = mmc;
host->spi = spi;
host->ones = ones;
/* Platform data is used to hook up things like card sensing
* and power switching gpios.
*/
host->pdata = mmc_spi_get_pdata(spi);
if (host->pdata)
mmc->ocr_avail = host->pdata->ocr_mask;
if (!mmc->ocr_avail) {
dev_warn(&spi->dev, "ASSUMING 3.2-3.4 V slot power\n");
mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34;
}
if (host->pdata && host->pdata->setpower) {
host->powerup_msecs = host->pdata->powerup_msecs;
if (!host->powerup_msecs || host->powerup_msecs > 250)
host->powerup_msecs = 250;
}
dev_set_drvdata(&spi->dev, mmc);
/* preallocate dma buffers */
host->data = kmalloc(sizeof(*host->data), GFP_KERNEL);
if (!host->data)
goto fail_nobuf1;
if (spi->master->dev.parent->dma_mask) {
struct device *dev = spi->master->dev.parent;
host->dma_dev = dev;
host->ones_dma = dma_map_single(dev, ones,
MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
host->data_dma = dma_map_single(dev, host->data,
sizeof(*host->data), DMA_BIDIRECTIONAL);
/* REVISIT in theory those map operations can fail... */
dma_sync_single_for_cpu(host->dma_dev,
host->data_dma, sizeof(*host->data),
DMA_BIDIRECTIONAL);
}
/* setup message for status/busy readback */
spi_message_init(&host->readback);
host->readback.is_dma_mapped = (host->dma_dev != NULL);
spi_message_add_tail(&host->status, &host->readback);
host->status.tx_buf = host->ones;
host->status.tx_dma = host->ones_dma;
host->status.rx_buf = &host->data->status;
host->status.rx_dma = host->data_dma + offsetof(struct scratch, status);
host->status.cs_change = 1;
/* register card detect irq */
if (host->pdata && host->pdata->init) {
status = host->pdata->init(&spi->dev, mmc_spi_detect_irq, mmc);
if (status != 0)
goto fail_glue_init;
}
/* pass platform capabilities, if any */
if (host->pdata) {
mmc->caps |= host->pdata->caps;
mmc->caps2 |= host->pdata->caps2;
}
status = mmc_add_host(mmc);
if (status != 0)
goto fail_add_host;
if (host->pdata && host->pdata->flags & MMC_SPI_USE_CD_GPIO) {
status = mmc_gpio_request_cd(mmc, host->pdata->cd_gpio,
host->pdata->cd_debounce);
if (status != 0)
goto fail_add_host;
}
if (host->pdata && host->pdata->flags & MMC_SPI_USE_RO_GPIO) {
has_ro = true;
status = mmc_gpio_request_ro(mmc, host->pdata->ro_gpio);
if (status != 0)
goto fail_add_host;
}
dev_info(&spi->dev, "SD/MMC host %s%s%s%s%s\n",
dev_name(&mmc->class_dev),
host->dma_dev ? "" : ", no DMA",
has_ro ? "" : ", no WP",
(host->pdata && host->pdata->setpower)
? "" : ", no poweroff",
(mmc->caps & MMC_CAP_NEEDS_POLL)
? ", cd polling" : "");
return 0;
fail_add_host:
mmc_remove_host (mmc);
fail_glue_init:
if (host->dma_dev)
dma_unmap_single(host->dma_dev, host->data_dma,
sizeof(*host->data), DMA_BIDIRECTIONAL);
kfree(host->data);
fail_nobuf1:
mmc_free_host(mmc);
mmc_spi_put_pdata(spi);
dev_set_drvdata(&spi->dev, NULL);
nomem:
kfree(ones);
return status;
}
static int mmc_spi_remove(struct spi_device *spi)
{
struct mmc_host *mmc = dev_get_drvdata(&spi->dev);
struct mmc_spi_host *host;
if (mmc) {
host = mmc_priv(mmc);
/* prevent new mmc_detect_change() calls */
if (host->pdata && host->pdata->exit)
host->pdata->exit(&spi->dev, mmc);
mmc_remove_host(mmc);
if (host->dma_dev) {
dma_unmap_single(host->dma_dev, host->ones_dma,
MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
dma_unmap_single(host->dma_dev, host->data_dma,
sizeof(*host->data), DMA_BIDIRECTIONAL);
}
kfree(host->data);
kfree(host->ones);
spi->max_speed_hz = mmc->f_max;
mmc_free_host(mmc);
mmc_spi_put_pdata(spi);
dev_set_drvdata(&spi->dev, NULL);
}
return 0;
}
static struct of_device_id mmc_spi_of_match_table[] = {
{ .compatible = "mmc-spi-slot", },
{},
};
static struct spi_driver mmc_spi_driver = {
.driver = {
.name = "mmc_spi",
.owner = THIS_MODULE,
.of_match_table = mmc_spi_of_match_table,
},
.probe = mmc_spi_probe,
.remove = mmc_spi_remove,
};
module_spi_driver(mmc_spi_driver);
MODULE_AUTHOR("Mike Lavender, David Brownell, "
"Hans-Peter Nilsson, Jan Nikitenko");
MODULE_DESCRIPTION("SPI SD/MMC host driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:mmc_spi");