4BA: Support for 4-bytes addressing via Extended Address Register

On some flash chips data with addresses more than 24-bit field
can address may be accessed by using Extended Address Register.
The register has 1-byte size and stores high byte of 32-bit address.
Then flash can be read from 3-bytes addressing mode with writing
high byte of address to this Register. By using this way we have
access to full memory of a chip. Some chips may support this method
only.

This patch provides code use Extended Address Register.

Patched files
-------------
chipdrivers.h
+ added functions declarations for spi4ba.c

flash.h
+ feature definitions added

flashrom.c
+ modified switch to 4-bytes addressing to support extended address register

spi4ba.h
+ definitions for 4-bytes addressing JEDEC commands
+ functions declarations from spi4ba.c (same as in chipdrivers.h, just to see)

spi4ba.c
+ functions for write Extended Address Register
+ functions for read/write/erase with Extended Address Register

Change-Id: I09a8aa11de2ca14901f142c67c83c4fa0def4e27
Signed-off-by: Boris Baykov <dev@borisbaykov.com>, Russia, Jan 2014
[clg: ported from
      https://www.flashrom.org/pipermail/flashrom/2015-January/013200.html ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-on: https://review.coreboot.org/20507
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

flash.h

@@ -120,8 +120,9 @@ enum write_granularity {
 #define FEATURE_OTP		(1 << 8)
 #define FEATURE_QPI		(1 << 9)
 /* Feature bits used for 4-bytes addressing mode */
-#define FEATURE_4BA_SUPPORT	(1 << 10)
-#define FEATURE_4BA_ONLY 	(1 << 11)
+#define FEATURE_4BA_SUPPORT		(1 << 10)
+#define FEATURE_4BA_ONLY 		(1 << 11)
+#define FEATURE_4BA_EXTENDED_ADDR_REG	(1 << 12)
 
 enum test_state {
 	OK = 0,