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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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