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-rw-r--r--drivers/misc/eeprom/at25.c19
-rw-r--r--include/linux/spi/eeprom.h10
2 files changed, 26 insertions, 3 deletions
diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index 01ab3c9b4cf7..0842c2994ee2 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -50,6 +50,7 @@ struct at25_data {
#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 @@ at25_ee_read(
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 @@ at25_ee_read(
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 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
/* 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 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
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 */
diff --git a/include/linux/spi/eeprom.h b/include/linux/spi/eeprom.h
index 306e7b1c69ed..403e007aef68 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;