diff options
Diffstat (limited to 'drivers/mmc/host/mmc_spi.c')
| -rw-r--r-- | drivers/mmc/host/mmc_spi.c | 1408 |
1 files changed, 1408 insertions, 0 deletions
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c new file mode 100644 index 0000000..f30327b --- /dev/null +++ b/drivers/mmc/host/mmc_spi.c @@ -0,0 +1,1408 @@ +/* + * 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/hrtimer.h> +#include <linux/delay.h> +#include <linux/blkdev.h> +#include <linux/dma-mapping.h> +#include <linux/crc7.h> +#include <linux/crc-itu-t.h> + +#include <linux/mmc/host.h> +#include <linux/mmc/mmc.h> /* for R1_SPI_* bit values */ + +#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 readblock_timeout ktime_set(0, 100 * 1000 * 1000) +#define writeblock_timeout ktime_set(0, 250 * 1000 * 1000) +#define r1b_timeout ktime_set(3, 0) + + +/****************************************************************************/ + +/* + * 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(host->spi, &host->readback); + if (status == 0) + status = host->readback.status; + + 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, ktime_t timeout, unsigned n, u8 byte) +{ + u8 *cp = host->data->status; + + timeout = ktime_add(timeout, ktime_get()); + + 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]; + } + + /* REVISIT investigate msleep() to avoid busy-wait I/O + * in at least some cases. + */ + if (ktime_to_ns(ktime_sub(ktime_get(), timeout)) > 0) + break; + } + return -ETIMEDOUT; +} + +static inline int +mmc_spi_wait_unbusy(struct mmc_spi_host *host, ktime_t timeout) +{ + return mmc_spi_skip(host, timeout, sizeof(host->data->status), 0); +} + +static int mmc_spi_readtoken(struct mmc_spi_host *host) +{ + return mmc_spi_skip(host, readblock_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; + 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) { + unsigned i; + + cp = host->data->status; + + /* 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... + */ + for (i = 2; i < 9; i++) { + value = mmc_spi_readbytes(host, 1); + if (value < 0) + goto done; + if (*cp != 0xff) + goto checkstatus; + } + value = -ETIMEDOUT; + goto done; + } + +checkstatus: + if (*cp & 0x80) { + dev_dbg(&host->spi->dev, "%s: INVALID RESPONSE, %02x\n", + tag, *cp); + value = -EBADR; + goto done; + } + + 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) + & cmd->resp[0]) + value = -EINVAL; + else if (R1_SPI_COM_CRC & cmd->resp[0]) + value = -EILSEQ; + else if ((R1_SPI_ERASE_SEQ | R1_SPI_ERASE_RESET) + & cmd->resp[0]) + value = -EIO; + /* 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: + cmd->resp[0] |= *cp << 8; + break; + + /* SPI R3, R4, or R7 == R1 + 4 bytes */ + case MMC_RSP_SPI_R3: + cmd->resp[1] = be32_to_cpu(get_unaligned((u32 *)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(host->spi, &host->m); + if (status == 0) + status = host->m.status; + + 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) +{ + struct spi_device *spi = host->spi; + int status, i; + struct scratch *scratch = host->data; + + 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(spi, &host->m); + if (status == 0) + status = host->m.status; + + 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. + */ + switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) { + 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 = 1; i < sizeof(scratch->status); i++) { + if (scratch->status[i] != 0) + return 0; + } + return mmc_spi_wait_unbusy(host, writeblock_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) +{ + struct spi_device *spi = host->spi; + int status; + struct scratch *scratch = host->data; + + /* 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); + + 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); + } + + status = spi_sync(spi, &host->m); + if (status == 0) + status = host->m.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); + } + + } else { + dev_dbg(&spi->dev, "read error %02x (%d)\n", status, status); + + /* we've read extra garbage, timed out, etc */ + if (status < 0) + return status; + + /* low four bits are an R2 subset, fifth seems to be + * vendor specific ... map them all to generic error.. + */ + return -EIO; + } + + 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); + + 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; + + /* 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, 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); + 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); + else + status = mmc_spi_readblock(host, t); + 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); + kunmap(sg->page); + 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(spi, &host->m); + if (tmp == 0) + tmp = host->m.status; + + 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, writeblock_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; + +#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 + + /* 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); + if (mrq->stop) + status = mmc_spi_command_send(host, mrq, mrq->stop, 0); + else + mmc_cs_off(host); + } + + 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; + + 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_w8r8(host->spi, 0x00) < 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 int mmc_spi_get_ro(struct mmc_host *mmc) +{ + struct mmc_spi_host *host = mmc_priv(mmc); + + if (host->pdata && host->pdata->get_ro) + return host->pdata->get_ro(mmc->parent); + /* board doesn't support read only detection; assume writeable */ + return 0; +} + + +static const struct mmc_host_ops mmc_spi_ops = { + .request = mmc_spi_request, + .set_ios = mmc_spi_set_ios, + .get_ro = mmc_spi_get_ro, +}; + + +/****************************************************************************/ + +/* + * 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; + + /* 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 it seems to be a + * bit less troublesome on some hardware ... unclear why. + */ + 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 can use the bus safely iff nobody else will interfere with + * us. That is, either we have the experimental exclusive access + * primitives ... or else there's nobody to share it with. + */ + if (spi->master->num_chipselect > 1) { + struct device *parent = spi->dev.parent; + + /* If there are multiple devices on this bus, we + * can't proceed. + */ + spin_lock(&parent->klist_children.k_lock); + if (parent->klist_children.k_list.next + != parent->klist_children.k_list.prev) + status = -EMLINK; + else + status = 0; + spin_unlock(&parent->klist_children.k_lock); + if (status < 0) { + dev_err(&spi->dev, "can't share SPI bus\n"); + return status; + } + + /* REVISIT we can't guarantee another device won't + * be added later. It's uncommon though ... for now, + * work as if this is safe. + */ + dev_warn(&spi->dev, "ASSUMING unshared SPI bus!\n"); + } + + /* 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; + + /* As long as we keep track of the number of successfully + * transmitted blocks, we're good for multiwrite. + */ + mmc->caps = MMC_CAP_SPI | MMC_CAP_MULTIWRITE; + + /* 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 = spi->dev.platform_data; + 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->cdev.dev->dma_mask) { + struct device *dev = spi->master->cdev.dev; + + 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; + } + + status = mmc_add_host(mmc); + if (status != 0) + goto fail_add_host; + + dev_info(&spi->dev, "SD/MMC host %s%s%s%s\n", + mmc->class_dev.bus_id, + host->dma_dev ? "" : ", no DMA", + (host->pdata && host->pdata->get_ro) + ? "" : ", no WP", + (host->pdata && host->pdata->setpower) + ? "" : ", no poweroff"); + 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); + dev_set_drvdata(&spi->dev, NULL); + +nomem: + kfree(ones); + return status; +} + + +static int __devexit 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); + dev_set_drvdata(&spi->dev, NULL); + } + return 0; +} + + +static struct spi_driver mmc_spi_driver = { + .driver = { + .name = "mmc_spi", + .bus = &spi_bus_type, + .owner = THIS_MODULE, + }, + .probe = mmc_spi_probe, + .remove = __devexit_p(mmc_spi_remove), +}; + + +static int __init mmc_spi_init(void) +{ + return spi_register_driver(&mmc_spi_driver); +} +module_init(mmc_spi_init); + + +static void __exit mmc_spi_exit(void) +{ + spi_unregister_driver(&mmc_spi_driver); +} +module_exit(mmc_spi_exit); + + +MODULE_AUTHOR("Mike Lavender, David Brownell, " + "Hans-Peter Nilsson, Jan Nikitenko"); +MODULE_DESCRIPTION("SPI SD/MMC host driver"); +MODULE_LICENSE("GPL"); |
