add some more Blackfin docs

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

README

@@ -3517,6 +3517,11 @@ For PowerPC, the following registers have specific use:
     average for all boards 752 bytes for the whole U-Boot image,
     624 text + 127 data).
 
+On Blackfin, the normal C ABI (except for P5) is followed as documented here:
+	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
+
+    ==> U-Boot will use P5 to hold a pointer to the global data
+
 On ARM, the following registers are used:
 
 	R0:	function argument word/integer result

doc/README.blackfin

@@ -0,0 +1,46 @@
+Notes for the Blackfin architecture port of Das U-Boot
+
+ =========
+ ! ABOUT !
+ =========
+
+<marketing blurb>
+Blackfin Processors embody a new breed of 16/32-bit embedded processor, ideally
+suited for products where a convergence of capabilities are necessary -
+multi-format audio, video, voice and image processing; multi-mode baseband and
+packet processing; control processing; and real-time security.  The Blackfin's
+unique combination of software flexibility and scalability has gained it
+widespread adoption in convergent applications.
+</marketing blurb>
+
+The Blackfin processor is wholly developed by Analog Devices Inc.
+
+ ===========
+ ! SUPPORT !
+ ===========
+
+All open source code for the Blackfin processors are being handled via our
+collaborative website:
+http://blackfin.uclinux.org/
+
+In particular, bug reports, feature requests, help etc... for Das U-Boot are
+handled in the Das U-Boot sub project:
+http://blackfin.uclinux.org/gf/project/u-boot
+
+This website is backed both by an open source community as well as a dedicated
+team from Analog Devices Inc.
+
+ =============
+ ! TOOLCHAIN !
+ =============
+
+To compile the Blackfin aspects, you'll need the GNU toolchain configured for
+the Blackfin processor.  You can obtain such a cross-compiler here:
+http://blackfin.uclinux.org/gf/project/toolchain
+
+ =================
+ ! DOCUMENTATION !
+ =================
+
+For Blackfin specific documentation, you can visit our dedicated doc wiki:
+http://docs.blackfin.uclinux.org/doku.php?id=bootloaders:u-boot

doc/README.standalone

@@ -19,11 +19,11 @@ Design Notes on Exporting U-Boot Functions to Standalone Applications:
    thus the compiler cannot perform type checks on these assignments.
 
 2. The pointer to the jump table is passed to the application in a
-   machine-dependent way. PowerPC, ARM and MIPS architectures use a
-   dedicated register to hold the pointer to the 'global_data'
-   structure: r29 on PowerPC, r8 on ARM and k0 on MIPS. The x86
-   architecture does not use such a register; instead, the pointer to
-   the 'global_data' structure is passed as 'argv[-1]' pointer.
+   machine-dependent way. PowerPC, ARM, MIPS and Blackfin architectures
+   use a dedicated register to hold the pointer to the 'global_data'
+   structure: r29 on PowerPC, r8 on ARM, k0 on MIPS, and P5 on Blackfin.
+   The x86 architecture does not use such a register; instead, the pointer
+   to the 'global_data' structure is passed as 'argv[-1]' pointer.
 
    The application can access the 'global_data' structure in the same
    way as U-Boot does:
@@ -49,11 +49,12 @@ Design Notes on Exporting U-Boot Functions to Standalone Applications:
 4. The default load and start addresses of the applications are as
    follows:
 
-		Load address	Start address
-	x86	0x00040000	0x00040000
-	PowerPC	0x00040000	0x00040004
-	ARM	0x0c100000	0x0c100000
-	MIPS	0x80200000	0x80200000
+			Load address	Start address
+	x86		0x00040000	0x00040000
+	PowerPC		0x00040000	0x00040004
+	ARM		0x0c100000	0x0c100000
+	MIPS		0x80200000	0x80200000
+	Blackfin	0x00001000	0x00001000
 
    For example, the "hello world" application may be loaded and
    executed on a PowerPC board with the following commands: