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 but we also handle lack of block mode support and the block size
being greater than 512 (the maximum byte mode transfer size).

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>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 73 insertions, 20 deletions

diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index c2bad1195e3b..34b085d4024a 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -189,6 +189,67 @@ int sdio_set_block_size(struct sdio_func *func, unsigned blksz)
 
 EXPORT_SYMBOL_GPL(sdio_set_block_size);
 
+/* 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 addr, int incr_addr, u8 *buf, unsigned size)
+{
+        unsigned remainder = size;
+        unsigned max_blocks;
+        int ret;
+
+        /* Do the bulk of the transfer using block mode (if supported). */
+        if (func->card->cccr.multi_block) {
+                /* 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,
+                                func->num, addr, incr_addr, buf,
+                                blocks, func->cur_blksize);
+                        if (ret)
+                                return ret;
+
+                        remainder -= size;
+                        buf += size;
+                        if (incr_addr)
+                                addr += size;
+                }
+        }
+
+        /* Write the remainder using byte mode. */
+        while (remainder > 0) {
+                size = remainder;
+                if (size > func->cur_blksize)
+                        size = func->cur_blksize;
+                if (size > 512)
+                        size = 512; /* maximum size for byte mode */
+
+                ret = mmc_io_rw_extended(func->card, write, func->num, addr,
+                         incr_addr, buf, 1, size);
+                if (ret)
+                        return ret;
+
+                remainder -= size;
+                buf += size;
+                if (incr_addr)
+                        addr += size;
+        }
+        return 0;
+}
+
 /**
  *      sdio_readb - read a single byte from a SDIO function
  *      @func: SDIO function to access
@@ -252,15 +313,13 @@ EXPORT_SYMBOL_GPL(sdio_writeb);
  *      @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,
-                count);
+        return sdio_io_rw_ext_helper(func, 0, addr, 1, dst, count);
 }
 EXPORT_SYMBOL_GPL(sdio_memcpy_fromio);
 
@@ -271,15 +330,13 @@ EXPORT_SYMBOL_GPL(sdio_memcpy_fromio);
  *      @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,
-                count);
+        return sdio_io_rw_ext_helper(func, 1, addr, 1, src, count);
 }
 EXPORT_SYMBOL_GPL(sdio_memcpy_toio);
 
@@ -290,15 +347,13 @@ EXPORT_SYMBOL_GPL(sdio_memcpy_toio);
  *      @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,
-                count);
+        return sdio_io_rw_ext_helper(func, 0, addr, 0, dst, count);
 }
 
 EXPORT_SYMBOL_GPL(sdio_readsb);
@@ -310,15 +365,13 @@ EXPORT_SYMBOL_GPL(sdio_readsb);
  *      @src: buffer that contains the data to write
  *      @count: number of bytes to write
  *
- *      Writes up to 512 bytes to the specified FIFO of a given SDIO
- *      function. Return value indicates if the transfer succeeded or
- *      not.
+ *      Writes to the specified FIFO of a given SDIO function. Return
+ *      value indicates if the transfer succeeded or not.
  */
 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,
-                count);
+        return sdio_io_rw_ext_helper(func, 1, addr, 0, src, count);
 }
 EXPORT_SYMBOL_GPL(sdio_writesb);