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>
diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index 01ab3c9..0842c299 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -50,6 +50,7 @@
#define AT25_SR_BP1 0x08
#define AT25_SR_WPEN 0x80 /* writeprotect enable */
+#define AT25_INSTR_BIT3 0x08 /* Additional address bit in instr */
#define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */
@@ -75,6 +76,7 @@
ssize_t status;
struct spi_transfer t[2];
struct spi_message m;
+ u8 instr;
if (unlikely(offset >= at25->bin.size))
return 0;
@@ -84,7 +86,12 @@
return count;
cp = command;
- *cp++ = AT25_READ;
+
+ instr = AT25_READ;
+ if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+ if (offset >= (1U << (at25->addrlen * 8)))
+ instr |= AT25_INSTR_BIT3;
+ *cp++ = instr;
/* 8/16/24-bit address is written MSB first */
switch (at25->addrlen) {
@@ -167,14 +174,14 @@
/* For write, rollover is within the page ... so we write at
* most one page, then manually roll over to the next page.
*/
- bounce[0] = AT25_WRITE;
mutex_lock(&at25->lock);
do {
unsigned long timeout, retries;
unsigned segment;
unsigned offset = (unsigned) off;
- u8 *cp = bounce + 1;
+ u8 *cp = bounce;
int sr;
+ u8 instr;
*cp = AT25_WREN;
status = spi_write(at25->spi, cp, 1);
@@ -184,6 +191,12 @@
break;
}
+ instr = AT25_WRITE;
+ if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+ if (offset >= (1U << (at25->addrlen * 8)))
+ instr |= AT25_INSTR_BIT3;
+ *cp++ = instr;
+
/* 8/16/24-bit address is written MSB first */
switch (at25->addrlen) {
default: /* case 3 */