Support M95040 SPI EEPROM

Updated the generic SPI EEPROM driver AT25 for support of an additional address
bit in the instruction byte. Certain EEPROMS have a size that is larger than the
number of address bytes would allow (e.g. like M95040 from ST that has 512 Byte
size but uses only one address byte (A0 to A7) for addressing.) For the extra
address bit (A8, A16 or A24) bit 3 of the instruction byte is used. This
instruction bit is normally defined as don't care for other AT25 like chips.

Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/spi/eeprom.h b/include/linux/spi/eeprom.h
index 306e7b1..403e007 100644
--- a/include/linux/spi/eeprom.h
+++ b/include/linux/spi/eeprom.h
@@ -20,6 +20,16 @@ struct spi_eeprom {
 #define	EE_ADDR3	0x0004			/* 24 bit addrs */
 #define	EE_READONLY	0x0008			/* disallow writes */
 
+	/*
+	 * Certain EEPROMS have a size that is larger than the number of address
+	 * bytes would allow (e.g. like M95040 from ST that has 512 Byte size
+	 * but uses only one address byte (A0 to A7) for addressing.) For
+	 * the extra address bit (A8, A16 or A24) bit 3 of the instruction byte
+	 * is used. This instruction bit is normally defined as don't care for
+	 * other AT25 like chips.
+	 */
+#define EE_INSTR_BIT3_IS_ADDR	0x0010
+
 	/* for exporting this chip's data to other kernel code */
 	void (*setup)(struct memory_accessor *mem, void *context);
 	void *context;