| Message ID | 1512740801-21142-1-git-send-email-geert+renesas@glider.be |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [v2] eeprom: at25: Add DT support for EEPROMs with odd address bits | expand |
On Fri, Dec 08, 2017 at 02:46:41PM +0100, Geert Uytterhoeven wrote: > 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> > --- > 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(-) Reviewed-by: Rob Herring <robh@kernel.org> -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2017-12-12 21:54 GMT+01:00 Rob Herring <robh@kernel.org>: > On Fri, Dec 08, 2017 at 02:46:41PM +0100, Geert Uytterhoeven wrote: >> 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> >> --- >> 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(-) > > Reviewed-by: Rob Herring <robh@kernel.org> Reviewed-by: Ivo Sieben <meltedpianoman@gmail.com> -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;
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> --- 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(-)