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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2017-12-08 16:46:41 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-18 17:59:17 +0300 |
| commit | f8d3bc10041914cceef4585a38cfdc071724b2a7 (patch) | |
| tree | 3146eb5bdf0ac3681852d1719d07f0826eb8c6b7 | |
| parent | eb90826babfb13cf5cf240187d56cdfed9df5064 (diff) | |
| download | linux-f8d3bc10041914cceef4585a38cfdc071724b2a7.tar.xz | |
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 <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | Documentation/devicetree/bindings/eeprom/at25.txt | 4 | ||||
| -rw-r--r-- | drivers/misc/eeprom/at25.c | 3 |
2 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/eeprom/at25.txt b/Documentation/devicetree/bindings/eeprom/at25.txt index e823d90b802f..b3bde97dc199 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 5afe4cd16569..9282ffd607ff 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; |