mmc: sdhci-acpi: add SDHCI ACPI driver

Add a driver for SDHCI controllers enumerated via ACPI and identified
by the ACPI Compatibility ID PNP0D40 (or other SDHCI-specific ACPI
hardware IDs in the future).

[rjw: Added the changelog.]
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Chris Ball <cjb@laptop.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 9bf10e7..56eac10 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -81,6 +81,18 @@
 
 	  If unsure, say Y.
 
+config MMC_SDHCI_ACPI
+	tristate "SDHCI support for ACPI enumerated SDHCI controllers"
+	depends on MMC_SDHCI && ACPI
+	help
+	  This selects support for ACPI enumerated SDHCI controllers,
+	  identified by ACPI Compatibility ID PNP0D40 or specific
+	  ACPI Hardware IDs.
+
+	  If you have a controller with this interface, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_SDHCI_PLTFM
 	tristate "SDHCI platform and OF driver helper"
 	depends on MMC_SDHCI