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>
diff --git a/spi4ba.h b/spi4ba.h
index 15feecb..f2e7bc5 100644
--- a/spi4ba.h
+++ b/spi4ba.h
@@ -36,6 +36,16 @@
 #define JEDEC_EXIT_4_BYTE_ADDR_MODE_OUTSIZE	0x01
 #define JEDEC_EXIT_4_BYTE_ADDR_MODE_INSIZE	0x00
 
+/* Write Extended Address Register */
+#define JEDEC_WRITE_EXT_ADDR_REG		0xC5
+#define JEDEC_WRITE_EXT_ADDR_REG_OUTSIZE	0x02
+#define JEDEC_WRITE_EXT_ADDR_REG_INSIZE		0x00
+
+/* Read Extended Address Register */
+#define JEDEC_READ_EXT_ADDR_REG			0xC8
+#define JEDEC_READ_EXT_ADDR_REG_OUTSIZE		0x01
+#define JEDEC_READ_EXT_ADDR_REG_INSIZE		0x01
+
 /* enter 4-bytes addressing mode */
 int spi_enter_4ba_b7(struct flashctx *flash);
 int spi_enter_4ba_b7_we(struct flashctx *flash);
@@ -50,5 +60,15 @@
 int spi_block_erase_52_4ba(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 int spi_block_erase_d8_4ba(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 
+/* read/write flash bytes from 3-bytes addressing mode using extended address register */
+int spi_byte_program_4ba_ereg(struct flashctx *flash, unsigned int addr, uint8_t databyte);
+int spi_nbyte_program_4ba_ereg(struct flashctx *flash, unsigned int addr, const uint8_t *bytes, unsigned int len);
+int spi_nbyte_read_4ba_ereg(struct flashctx *flash, unsigned int addr, uint8_t *bytes, unsigned int len);
+
+/* erase flash bytes from 3-bytes addressing mode using extended address register */
+int spi_block_erase_20_4ba_ereg(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
+int spi_block_erase_52_4ba_ereg(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
+int spi_block_erase_d8_4ba_ereg(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
+
 
 #endif /* __SPI_4BA_H__ */