1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index ff27c8c71355..0f687cdeb064 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -406,6 +406,36 @@ void sdio_writeb(struct sdio_func *func, u8 b, unsigned int addr, int *err_ret)
 EXPORT_SYMBOL_GPL(sdio_writeb);
 
 /**
+ *      sdio_writeb_readb - write and read a byte from SDIO function
+ *      @func: SDIO function to access
+ *      @write_byte: byte to write
+ *      @addr: address to write to
+ *      @err_ret: optional status value from transfer
+ *
+ *      Performs a RAW (Read after Write) operation as defined by SDIO spec -
+ *      single byte is written to address space of a given SDIO function and
+ *      response is read back from the same address, both using single request.
+ *      If there is a problem with the operation, 0xff is returned and
+ *      @err_ret will contain the error code.
+ */
+u8 sdio_writeb_readb(struct sdio_func *func, u8 write_byte,
+        unsigned int addr, int *err_ret)
+{
+        int ret;
+        u8 val;
+
+        ret = mmc_io_rw_direct(func->card, 1, func->num, addr,
+                        write_byte, &val);
+        if (err_ret)
+                *err_ret = ret;
+        if (ret)
+                val = 0xff;
+
+        return val;
+}
+EXPORT_SYMBOL_GPL(sdio_writeb_readb);
+
+/**
  *      sdio_memcpy_fromio - read a chunk of memory from a SDIO function
  *      @func: SDIO function to access
  *      @dst: buffer to store the data