Certain EEPROMS have a size that is larger than the number of address
bytes would allow, and store the MSB of the address in bit 3 of the
instruction byte.
This can be described in platform data using EE_INSTR_BIT3_IS_ADDR, or
in DT using the obsolete legacy "at25,addr-mode" property.
But currently there exists no non-deprecated way to describe this in DT.
Hence extend the existing "address-width" DT property to allow
specifying 9 address bits, and enable support for that in the driver.
This has been tested with a Microchip 25LC040A.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
v2:
- Do not consider odd address widths of 17 or 25 bits,
- Move handling inside the switch() statement.
---
Documentation/devicetree/bindings/eeprom/at25.txt | 4 +++-
drivers/misc/eeprom/at25.c | 3 +++
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/eeprom/at25.txt b/Documentation/devicetree/bindings/eeprom/at25.txt
index e823d90b802f7f8f..b3bde97dc19913ea 100644
--- a/Documentation/devicetree/bindings/eeprom/at25.txt
+++ b/Documentation/devicetree/bindings/eeprom/at25.txt
@@ -11,7 +11,9 @@ Required properties:
- spi-max-frequency : max spi frequency to use
- pagesize : size of the eeprom page
- size : total eeprom size in bytes
-- address-width : number of address bits (one of 8, 16, or 24)
+- address-width : number of address bits (one of 8, 9, 16, or 24).
+ For 9 bits, the MSB of the address is sent as bit 3 of the instruction
+ byte, before the address byte.
Optional properties:
- spi-cpha : SPI shifted clock phase, as per spi-bus bindings.
diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index 5afe4cd165699060..9282ffd607ff2799 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -276,6 +276,9 @@ static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
return -ENODEV;
}
switch (val) {
+ case 9:
+ chip->flags |= EE_INSTR_BIT3_IS_ADDR;
+ /* fall through */
case 8:
chip->flags |= EE_ADDR1;
break;
--
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
