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    Subject[patch 3/4] sdio: extend sdio_readsb() and friends to handle any length of buffer
    -- 
    David Vrabel, Software Engineer, Drivers group Tel: +44 (0)1223 692562
    CSR plc, Churchill House, Cambridge Business Park, Cowley Road, CB4 0WZ


    .
    sdio: extend sdio_readsb() and friends to handle any length of buffer

    Extend sdio_readsb(), sdio_writesb(), sdio_memcpy_fromio(), and
    sdio_memcpy_toio() to handle any length of buffer by splitting the transfer
    into several IO_RW_EXTENDED commands. Typically, a transfer would be split
    into a single block mode transfer followed by a byte mode transfer for the
    remainder.

    For this to work the block size must be limited to the maximum size of a
    byte mode transfer (512 bytes). This limitation could be revisited if
    there are any cards out there that require a block size > 512.
    host->max_seg_size <= host->max_req_size so there's no need to check both
    when determining the maximum data size for a single command.

    Signed-off-by: David Vrabel <david.vrabel@csr.com>
    ---
    Index: mmc/drivers/mmc/core/sdio_io.c
    ===================================================================
    --- mmc.orig/drivers/mmc/core/sdio_io.c 2007-08-07 07:27:31.000000000 +0100
    +++ mmc/drivers/mmc/core/sdio_io.c 2007-08-07 07:35:02.000000000 +0100
    @@ -153,6 +153,13 @@
    {
    int ret;

    + /* The standard permits block sizes up to 2048 bytes, but
    + * sdio_readsb() etc. can only work with block size <= 512. */
    + if (blksz > 512) {
    + blksz = 512;
    + dev_warn(&func->dev, "block size limited to 512 bytes\n");
    + }
    +
    ret = mmc_io_rw_direct(func->card, 1, 0,
    SDIO_FBR_BASE(func->num) + SDIO_FBR_BLKSIZE,
    blksz & 0xff, NULL);
    @@ -227,6 +234,48 @@

    EXPORT_SYMBOL_GPL(sdio_writeb);

    +/* Split an arbitrarily sized data transfer into several
    + * IO_RW_EXTENDED commands. */
    +static int sdio_io_rw_ext_helper(struct sdio_func *func, int write,
    + unsigned fn, unsigned addr, int incr_addr, u8 *buf, unsigned size)
    +{
    + unsigned remainder = size;
    + unsigned max_blocks;
    + int ret;
    +
    + /* Blocks per command is limited by host count, host transfer size
    + (we only use a single sg entry) and the maximum for IO_RW_EXTENDED
    + of 511 blocks. */
    + max_blocks = min(min(
    + func->card->host->max_blk_count,
    + func->card->host->max_seg_size / func->cur_blksize),
    + 511u);
    +
    + while (remainder > func->cur_blksize) {
    + unsigned blocks;
    +
    + blocks = remainder % func->cur_blksize;
    + if (blocks > max_blocks)
    + blocks = max_blocks;
    + size = blocks * func->cur_blksize;
    +
    + ret = mmc_io_rw_extended(func->card, write, fn, addr,
    + incr_addr, buf, blocks, func->cur_blksize);
    + if (ret)
    + return ret;
    +
    + remainder -= size;
    + buf += size;
    + if (incr_addr)
    + addr += size;
    + }
    +
    + if (remainder)
    + ret = mmc_io_rw_extended(func->card, write, fn, addr,
    + incr_addr, buf, 1, remainder);
    + return ret;
    +}
    +
    /**
    * sdio_memcpy_fromio - read a chunk of memory from a SDIO function
    * @func: SDIO function to access
    @@ -234,14 +283,13 @@
    * @addr: address to begin reading from
    * @count: number of bytes to read
    *
    - * Reads up to 512 bytes from the address space of a given SDIO
    - * function. Return value indicates if the transfer succeeded or
    - * not.
    + * Reads from the address space of a given SDIO function. Return
    + * value indicates if the transfer succeeded or not.
    */
    int sdio_memcpy_fromio(struct sdio_func *func, void *dst,
    unsigned int addr, int count)
    {
    - return mmc_io_rw_extended(func->card, 0, func->num, addr, 0, dst,
    + return sdio_io_rw_ext_helper(func, 0, func->num, addr, 1, dst,
    count);
    }

    @@ -254,14 +302,13 @@
    * @src: buffer that contains the data to write
    * @count: number of bytes to write
    *
    - * Writes up to 512 bytes to the address space of a given SDIO
    - * function. Return value indicates if the transfer succeeded or
    - * not.
    + * Writes to the address space of a given SDIO function. Return
    + * value indicates if the transfer succeeded or not.
    */
    int sdio_memcpy_toio(struct sdio_func *func, unsigned int addr,
    void *src, int count)
    {
    - return mmc_io_rw_extended(func->card, 1, func->num, addr, 0, src,
    + return sdio_io_rw_ext_helper(func, 1, func->num, addr, 1, src,
    count);
    }

    @@ -272,14 +319,13 @@
    * @addr: address of (single byte) FIFO
    * @count: number of bytes to read
    *
    - * Reads up to 512 bytes from the specified FIFO of a given SDIO
    - * function. Return value indicates if the transfer succeeded or
    - * not.
    + * Reads from the specified FIFO of a given SDIO function. Return
    + * value indicates if the transfer succeeded or not.
    */
    int sdio_readsb(struct sdio_func *func, void *dst, unsigned int addr,
    int count)
    {
    - return mmc_io_rw_extended(func->card, 0, func->num, addr, 1, dst,
    + return sdio_io_rw_ext_helper(func, 0, func->num, addr, 0, dst,
    count);
    }

    @@ -299,7 +345,7 @@
    int sdio_writesb(struct sdio_func *func, unsigned int addr, void *src,
    int count)
    {
    - return mmc_io_rw_extended(func->card, 1, func->num, addr, 1, src,
    + return sdio_io_rw_ext_helper(func, 1, func->num, addr, 0, src,
    count);
    }

    Index: mmc/drivers/mmc/core/sdio_ops.c
    ===================================================================
    --- mmc.orig/drivers/mmc/core/sdio_ops.c 2007-08-07 07:27:27.000000000 +0100
    +++ mmc/drivers/mmc/core/sdio_ops.c 2007-08-07 07:27:31.000000000 +0100
    @@ -88,7 +88,7 @@
    }

    int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
    - unsigned addr, int bang, u8 *buf, unsigned size)
    + unsigned addr, int incr_addr, u8 *buf, unsigned blocks, unsigned blksz)
    {
    struct mmc_request mrq;
    struct mmc_command cmd;
    @@ -97,7 +97,7 @@

    BUG_ON(!card);
    BUG_ON(fn > 7);
    - BUG_ON(size > 512);
    + BUG_ON(blocks == 1 && blksz > 512);

    memset(&mrq, 0, sizeof(struct mmc_request));
    memset(&cmd, 0, sizeof(struct mmc_command));
    @@ -109,18 +109,22 @@
    cmd.opcode = SD_IO_RW_EXTENDED;
    cmd.arg = write ? 0x80000000 : 0x00000000;
    cmd.arg |= fn << 28;
    - cmd.arg |= bang ? 0x00000000 : 0x04000000;
    + cmd.arg |= incr_addr ? 0x04000000 : 0x00000000;
    cmd.arg |= addr << 9;
    - cmd.arg |= (size == 512) ? 0 : size;
    + if (blocks > 1) {
    + cmd.arg |= 0x08000000;
    + cmd.arg |= blocks;
    + } else
    + cmd.arg |= (blksz == 512) ? 0 : blksz;
    cmd.flags = MMC_RSP_R5 | MMC_CMD_ADTC;

    - data.blksz = size;
    - data.blocks = 1;
    + data.blksz = blksz;
    + data.blocks = blocks;
    data.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ;
    data.sg = &sg;
    data.sg_len = 1;

    - sg_init_one(&sg, buf, size);
    + sg_init_one(&sg, buf, blksz * blocks);

    mmc_set_data_timeout(&data, card, 0);

    Index: mmc/drivers/mmc/core/sdio_ops.h
    ===================================================================
    --- mmc.orig/drivers/mmc/core/sdio_ops.h 2007-08-07 07:27:27.000000000 +0100
    +++ mmc/drivers/mmc/core/sdio_ops.h 2007-08-07 07:27:31.000000000 +0100
    @@ -16,7 +16,7 @@
    int mmc_io_rw_direct(struct mmc_card *card, int write, unsigned fn,
    unsigned addr, u8 in, u8* out);
    int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
    - unsigned addr, int bang, u8 *data, unsigned size);
    + unsigned addr, int incr_addr, u8 *buf, unsigned blocks, unsigned blksz);

    #endif
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