sdhci and mmc implementation

sdhci:
- Add semaphore for interrupt management
- Add basic operations (setting clock, executing a command)
- Add early initialization (clocks and power up)
- Wrap the bus in a C++ class to ease usage
- Expose API to MMC bus manager
- TODO: manage card insertion and removal interrupts
- TODO: use MSI when available

mmc_bus:
- Implements SD card management independant of the way we access the bus
  (later on different drivers can provide the same API as SDHCI)
- Worker thread to do the initialization
- Implement card initialization process up until getting an RCA from the
  card. This is the generic part to assign an ID to the card, after this
  point commands can be targetted at the specific card so it can be
  handed over to the mmc_disk driver.
- TODO: initialization for non-SDHC cards which do not reply to CMD8.

Change-Id: I71950ca3ce206378a68fa7f97c19f638183d6cdd
Reviewed-on: https://review.haiku-os.org/c/1032
Reviewed-by: waddlesplash <[email protected]>

headers/private/drivers/mmc.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2019, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Adrien Destugues, [email protected]
+ */
+#ifndef _MMC_H
+#define _MMC_H
+
+
+#include <device_manager.h>
+
+
+#define MMC_BUS_MODULE_NAME "bus_managers/mmc_bus/driver_v1"
+
+
+// Interface between mmc_bus and underlying implementation
+typedef struct mmc_bus_interface {
+	driver_module_info info;
+
+	status_t (*set_clock)(void* controller, uint32_t kilohertz);
+	status_t (*execute_command)(void* controller, uint8_t command,
+		uint32_t argument, uint32_t* result);
+} mmc_bus_interface;
+
+
+#endif /* _MMC_H */