sd: Add sdmmc protocol stack

Add SDMMC driver to subsystem. SDMMC driver will handle initialization,
as well as SDMMC I/O. SD mode support is currently supported, SPI mode
support is not.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>

subsys/sd/CMakeLists.txt

@@ -4,5 +4,5 @@ if (CONFIG_SD_STACK)
   zephyr_interface_library_named(SD)
 
   zephyr_library()
-  zephyr_library_sources (sd.c)
+  zephyr_library_sources (sd.c sdmmc.c)
 endif()

subsys/sd/Kconfig

@@ -1,4 +1,4 @@
-# Copyright (c) 2022 NXP
+# Copyright 2022 NXP
 # SPDX-License-Identifier: Apache-2.0
 
 # SD stack configuration options
@@ -48,7 +48,11 @@ config SD_DATA_TIMEOUT
 
 config SD_BUFFER_SIZE
 	int
-	default 512
+	# If SDHC required buffer alignment, we need a full block size in
+	# internal buffer
+	default 512 if SDHC_BUFFER_ALIGNMENT != 1
+	# Otherwise, we only need 64 bytes to read SD switch function
+	default 64
 	help
 	  Size in bytes of internal buffer SD card uses for unaligned reads and
 	  internal data reads during initialization

subsys/sd/sd.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 NXP
+ * Copyright 2022 NXP
  *
  * SPDX-License-Identifier: Apache-2.0
  */