Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: r234524

o Fixes:
- When switching to 4-bit operation, send a SET_CLR_CARD_DETECT command
to disconnect the card-detect pull-up resistor from the DAT3 line before
sending the SET_BUS_WIDTH command.
- Add the missing "reserved" zero entry to the mantissa table used to
decode various CSD fields. This was causing SD cards to report that they
could run at 30 MHz instead of the maximum 25 MHz mandated in the spec.
o Enhancements:
- At the MMC layer, format various info from the CID into a string that
uniquely identifies the card instance (manufacturer number, serial
number, product name and revision, etc). Export it as an instance
variable.
- At the MMCSD layer, display the formatted card ID string, and also
report the clock speed of the hardware (not the card's max speed), and
the number of bits and number of blocks per transfer. It comes out like
this now:
mmcsd0: 968MB <SD SD01G 8.0 SN 276886905 MFG 08/2008 by 3 SD> at mmc0
22.5MHz/4bit/128-block
o Use DEVMETHOD_END.
o Use NULL instead of 0 for pointers.

PR: 156496
Submitted by: Ian Lepore

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Allow card reader bridge driver to report maximum supported transfer size.
sdhci supports up to 65535 blocks transfers, at91_mci - one block.

Enable multiblock operations disabled before to follow at91_mci driver
limitations.

Reviewed by: imp@

Set of mmc layer improvements:
- add MMC support.
- add SDHC support.
- add 4 and 8 bit bus width support.
- add High Speed bus timing support.

Add "caps" word to host bridge.

Propigate read-only status of cards. Right now it is read only at
device attach time. We may need to read this more often in the
future, but for now simplicity of implementation wins.

Submitted by: mav@

A careful reading of the disclaimer that is required to download the
SD Simplified specification, as well as other SD and SDIO
implemenations I've examined, suggest this disclaimer may be required.
It is unclear to me exactly what the license would be for, or why it
might be required. Err on the side of caution and include this
disclaimer so anybody deploying this code can judge for themselves. I
have no further unformation about the details.

Preliminary MMC stack. This stack supports SD 1.0 cards only, but
should be easily adapted to SD 2.0 (aka SDHC), SDIO, MMC and MMCplus
cards. At the present time, there's only one bridge driver for the
ARM9 based Atmel AT91RM9200.