linux-phytec-ti

mmc: host: omap_hsmmc: add voltage switch support for UHS SD card

UHS SD card i/o data line operates at 1.8V when in UHS speed
mode.

Add support for signal voltage switch to support UHS cards.

Also, enable CIRQ before checking for CLEV/DLEV. MMC module can
sense when the clock lines and data lines are driven high by the
card, if MMC is active and CIRQ can be used to keep the MMC
module active. This is required for voltage switching to succeed
and the card to enumerate in UHS mode.

Signed-off-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
[kishon@ti.com : cleanup the voltage switch sequence]
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
[nsekhar@ti.com: make card busy functions preempt safe]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>