For some unknown reason ELP_CTRL can't be accesed using
sdio_memcpy_* functions (any attemts to do so result in timeouts):

 wl1251: ERROR sdio write failed (-110)
 wl1251: ERROR sdio read failed (-110)
 wl1251: WARNING WLAN not ready

To fix this, add special IO functions for ELP_CTRL access that are
using sdio_readb/sdio_writeb. Similar handling is done in TI
reference driver from Android code drop.
Signed-off-by: NGrazvydas Ignotas <notasas@gmail.com>
Cc: Bob Copeland <me@bobcopeland.com>
Acked-by: NKalle Valo <kalle.valo@iki.fi>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

The same partition setting code can be used for both SPI and SDIO
modes, if we remove the spi-specific commands and use the more
generic buffer write routines.  Do that and move it to io.c
since it deals with register/memory address offsets.
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Signed-off-by: NKalle Valo <kalle.valo@nokia.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Introduce an ops struct with read, write, and reset functions to
abstract away the details of the wl1251 bus interface.  Doing this
will allow SDIO to coexist with SPI by supplying its own I/O
routines.
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Signed-off-by: NKalle Valo <kalle.valo@nokia.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

In order to eventually support wl1251 spi and sdio interfaces, move
the register and memory transfer functions to a common file.  Also
rename wl1251_spi_mem_{read,write} to indicate its common usage.
We still use spi_read internally until SDIO interface is introduced
so nothing functional should change here.
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Signed-off-by: NKalle Valo <kalle.valo@nokia.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>