mmc_spi host driver

This is the latest version of the MMC-over-SPI support.  It works
on 2.6.23-rc2 plus git-mmc (from rc1-mm2), along with the preceding
patches which teach the rest of the MMC stack about SPI.

The main issue of note is that sometimes cards need to be power cycled
to recover after certain faults.  Also, it may sometimes be necessary
to disable CRCs.  ("modprobe mmc_core use_spi_crc=n")
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: mikael.starvik@axis.com,
Cc: Hans-Peter Nilsson <hp@axis.com>
Cc: Jan Nikitenko <jan.nikitenko@gmail.com>
Cc: Mike Lavender <mike@steroidmicros.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

MAINTAINERS

@@ -2567,6 +2567,12 @@ M:	drzeus-mmc@drzeus.cx
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 
+MULTIMEDIA CARD (MMC) ETC. OVER SPI
+P:	David Brownell
+M:	dbrownell@users.sourceforge.net
+L:	linux-kernel@vger.kernel.org
+S:	Odd fixes
+
 MULTISOUND SOUND DRIVER
 P:	Andrew Veliath
 M:	andrewtv@usa.net

drivers/mmc/host/Kconfig

@@ -100,3 +100,16 @@ config MMC_TIFM_SD
           To compile this driver as a module, choose M here: the
 	  module will be called tifm_sd.
 
+config MMC_SPI
+	tristate "MMC/SD over SPI (EXPERIMENTAL)"
+	depends on MMC && SPI_MASTER && !HIGHMEM && EXPERIMENTAL
+	select CRC7
+	select CRC_ITU_T
+	help
+	  Some systems accss MMC/SD cards using a SPI controller instead of
+	  using a "native" MMC/SD controller.  This has a disadvantage of
+	  being relatively high overhead, but a compensating advantage of
+	  working on many systems without dedicated MMC/SD controllers.
+
+	  If unsure, or if your system has no SPI master driver, say N.
+

drivers/mmc/host/Makefile

@@ -15,4 +15,5 @@ obj-$(CONFIG_MMC_AU1X)		+= au1xmmc.o
 obj-$(CONFIG_MMC_OMAP)		+= omap.o
 obj-$(CONFIG_MMC_AT91)		+= at91_mci.o
 obj-$(CONFIG_MMC_TIFM_SD)	+= tifm_sd.o
+obj-$(CONFIG_MMC_SPI)		+= mmc_spi.o
 

include/linux/spi/mmc_spi.h

+#ifndef __LINUX_SPI_MMC_SPI_H
+#define __LINUX_SPI_MMC_SPI_H
+
+struct device;
+struct mmc_host;
+
+/* Put this in platform_data of a device being used to manage an MMC/SD
+ * card slot.  (Modeled after PXA mmc glue; see that for usage examples.)
+ *
+ * REVISIT This is not a spi-specific notion.  Any card slot should be
+ * able to handle it.  If the MMC core doesn't adopt this kind of notion,
+ * switch the "struct device *" parameters over to "struct spi_device *".
+ */
+struct mmc_spi_platform_data {
+	/* driver activation and (optional) card detect irq hookup */
+	int (*init)(struct device *,
+		irqreturn_t (*)(int, void *),
+		void *);
+	void (*exit)(struct device *, void *);
+
+	/* sense switch on sd cards */
+	int (*get_ro)(struct device *);
+
+	/* how long to debounce card detect, in msecs */
+	u16 detect_delay;
+
+	/* power management */
+	u16 powerup_msecs;		/* delay of up to 250 msec */
+	u32 ocr_mask;			/* available voltages */
+	void (*setpower)(struct device *, unsigned int maskval);
+};
+
+#endif /* __LINUX_SPI_MMC_SPI_H */