[block] Replace gPXE block-device API with an iPXE asynchronous interface

The block device interface used in gPXE predates the invention of even
the old gPXE data-transfer interface, let alone the current iPXE
generic asynchronous interface mechanism.  Bring this old code up to
date, with the following benefits:

 o  Block device commands can be cancelled by the requestor.  The INT 13
    layer uses this to provide a global timeout on all INT 13 calls,
    with the result that an unexpected passive failure mode (such as
    an iSCSI target ACKing the request but never sending a response)
    will lead to a timeout that gets reported back to the INT 13 user,
    rather than simply freezing the system.

 o  INT 13,00 (reset drive) is now able to reset the underlying block
    device.  INT 13 users, such as DOS, that use INT 13,00 as a method
    for error recovery now have a chance of recovering.

 o  All block device commands are tagged, with a numerical tag that
    will show up in debugging output and in packet captures; this will
    allow easier interpretation of bug reports that include both
    sources of information.

 o  The extremely ugly hacks used to generate the boot firmware tables
    have been eradicated and replaced with a generic acpi_describe()
    method (exploiting the ability of iPXE interfaces to pass through
    methods to an underlying interface).  The ACPI tables are now
    built in a shared data block within .bss16, rather than each
    requiring dedicated space in .data16.

 o  The architecture-independent concept of a SAN device has been
    exposed to the iPXE core through the sanboot API, which provides
    calls to hook, unhook, boot, and describe SAN devices.  This
    allows for much more flexible usage patterns (such as hooking an
    empty SAN device and then running an OS installer via TFTP).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 82 insertions, 9 deletions

diff --git a/src/include/ipxe/sanboot.h b/src/include/ipxe/sanboot.h
index d27452cb6..913282eb5 100644
--- a/src/include/ipxe/sanboot.h
+++ b/src/include/ipxe/sanboot.h
@@ -1,20 +1,93 @@
 #ifndef _IPXE_SANBOOT_H
 #define _IPXE_SANBOOT_H
 
+/** @file
+ *
+ * iPXE sanboot API
+ *
+ * The sanboot API provides methods for hooking, unhooking,
+ * describing, and booting from SAN devices.
+ *
+ * The standard methods (readl()/writel() etc.) do not strictly check
+ * the type of the address parameter; this is because traditional
+ * usage does not necessarily provide the correct pointer type.  For
+ * example, code written for ISA devices at fixed I/O addresses (such
+ * as the keyboard controller) tend to use plain integer constants for
+ * the address parameter.
+ */
+
 FILE_LICENCE ( GPL2_OR_LATER );
 
-#include <ipxe/tables.h>
+#include <ipxe/api.h>
+#include <config/sanboot.h>
+
+struct uri;
+
+/**
+ * Calculate static inline sanboot API function name
+ *
+ * @v _prefix		Subsystem prefix
+ * @v _api_func		API function
+ * @ret _subsys_func	Subsystem API function
+ */
+#define SANBOOT_INLINE( _subsys, _api_func ) \
+	SINGLE_API_INLINE ( SANBOOT_PREFIX_ ## _subsys, _api_func )
+
+/**
+ * Provide a sanboot API implementation
+ *
+ * @v _prefix		Subsystem prefix
+ * @v _api_func		API function
+ * @v _func		Implementing function
+ */
+#define PROVIDE_SANBOOT( _subsys, _api_func, _func ) \
+	PROVIDE_SINGLE_API ( SANBOOT_PREFIX_ ## _subsys, _api_func, _func )
+
+/**
+ * Provide a static inline sanboot API implementation
+ *
+ * @v _prefix		Subsystem prefix
+ * @v _api_func		API function
+ */
+#define PROVIDE_SANBOOT_INLINE( _subsys, _api_func ) \
+	PROVIDE_SINGLE_API_INLINE ( SANBOOT_PREFIX_ ## _subsys, _api_func )
+
+/* Include all architecture-independent sanboot API headers */
+#include <ipxe/null_sanboot.h>
+
+/* Include all architecture-dependent sanboot API headers */
+#include <bits/sanboot.h>
 
-struct sanboot_protocol {
-	const char *prefix;
-	int ( * boot ) ( const char *root_path );
-};
+/**
+ * Hook SAN device
+ *
+ * @v uri		URI
+ * @v drive		Requested drive number
+ * @ret drive		Assigned drive number, or negative error
+ */
+int san_hook ( struct uri *uri, unsigned int drive );
 
-#define SANBOOT_PROTOCOLS \
-	__table ( struct sanboot_protocol, "sanboot_protocols" )
+/**
+ * Unhook SAN device
+ *
+ * @v drive		Drive number
+ */
+void san_unhook ( unsigned int drive );
 
-#define __sanboot_protocol __table_entry ( SANBOOT_PROTOCOLS, 01 )
+/**
+ * Attempt to boot from a SAN device
+ *
+ * @v drive		Drive number
+ * @ret rc		Return status code
+ */
+int san_boot ( unsigned int drive );
 
-extern int keep_san ( void );
+/**
+ * Describe SAN device for SAN-booted operating system
+ *
+ * @v drive		Drive number
+ * @ret rc		Return status code
+ */
+int san_describe ( unsigned int drive );
 
 #endif /* _IPXE_SANBOOT_H */