Hi Mark,
On 09/08/2019 14:54, Mark Rutland wrote:
On Fri, Aug 09, 2019 at 01:53:55PM +0100, Joe Burmeister wrote:
Many, though not all, AT25s have an instruction for chip erase.
If there is one in the datasheet, it can be added to device tree.
Erase can then be done in userspace via the sysfs API with a new
"erase" device attribute. This matches the eeprom_93xx46 driver's
"erase".
Signed-off-by: Joe Burmeister <joe.burmeister@xxxxxxxxxxxxx>
---
.../devicetree/bindings/eeprom/at25.txt | 2 +
drivers/misc/eeprom/at25.c | 83 ++++++++++++++++++-
2 files changed, 82 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/eeprom/at25.txt b/Documentation/devicetree/bindings/eeprom/at25.txt
index b3bde97dc199..c65d11e14c7a 100644
--- a/Documentation/devicetree/bindings/eeprom/at25.txt
+++ b/Documentation/devicetree/bindings/eeprom/at25.txt
@@ -19,6 +19,7 @@ Optional properties:
- spi-cpha : SPI shifted clock phase, as per spi-bus bindings.
- spi-cpol : SPI inverse clock polarity, as per spi-bus bindings.
- read-only : this parameter-less property disables writes to the eeprom
+- chip_erase_instruction : Chip erase instruction for this AT25, often 0xc7 or 0x62.
This should be using '-' rather than '_', as per general DT conventions
and as with the existing properties.
Obsolete legacy properties can be used in place of "size", "pagesize",
"address-width", and "read-only":
@@ -39,4 +40,5 @@ Example:
pagesize = <64>;
size = <32768>;
address-width = <16>;
+ chip_erase_instruction = <0x62>;
[...]
+ /* Optional chip erase instruction */
+ device_property_read_u8(&spi->dev, "chip_erase_instruction", &at25->erase_instr);
This will not behave as you expect, since you didn't mark the property as
8-bits.
Rats, I forgot to update the documentation. In my device tree I have
already found the /bit 8/ bit.
Read this as a u32 into the existing val temporary variable, as is done
for pagesize. You can add a warnign if it's out-of-range.
32bit would certainly read better in the device tree. I'll do that.
Thanks,
Mark.
Cheers,
Joe
