README: document CONFIG_ENV_IS_IN_SPI_FLASH

The option can be used to save the environment in spi flash.
Implementation code is already exist in command/env_sf.c. But
the documentation is missing.

This patch add the details for this option to the README file.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
This commit is contained in:
Wu, Josh 2014-07-01 19:30:13 +08:00 committed by Tom Rini
parent be354c1a21
commit bd83b59212

37
README
View File

@ -4069,6 +4069,43 @@ to save the current settings.
environment area within the total memory of your DataFlash placed
at the specified address.
- CONFIG_ENV_IS_IN_SPI_FLASH:
Define this if you have a SPI Flash memory device which you
want to use for the environment.
- CONFIG_ENV_OFFSET:
- CONFIG_ENV_SIZE:
These two #defines specify the offset and size of the
environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
aligned to an erase sector boundary.
- CONFIG_ENV_SECT_SIZE:
Define the SPI flash's sector size.
- CONFIG_ENV_OFFSET_REDUND (optional):
This setting describes a second storage area of CONFIG_ENV_SIZE
size used to hold a redundant copy of the environment data, so
that there is a valid backup copy in case there is a power failure
during a "saveenv" operation. CONFIG_ENV_OFFSET_RENDUND must be
aligned to an erase sector boundary.
- CONFIG_ENV_SPI_BUS (optional):
- CONFIG_ENV_SPI_CS (optional):
Define the SPI bus and chip select. If not defined they will be 0.
- CONFIG_ENV_SPI_MAX_HZ (optional):
Define the SPI max work clock. If not defined then use 1MHz.
- CONFIG_ENV_SPI_MODE (optional):
Define the SPI work mode. If not defined then use SPI_MODE_3.
- CONFIG_ENV_IS_IN_REMOTE:
Define this if you have a remote memory space which you