From f8d3bc10041914cceef4585a38cfdc071724b2a7 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 8 Dec 2017 14:46:41 +0100 Subject: [PATCH] eeprom: at25: Add DT support for EEPROMs with odd address bits 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 Reviewed-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- 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 e823d90..b3bde97 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 5afe4cd..9282ffd 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