We need distinguish the following two situations in various SPI APIs:
- given chip select num is invalid
- given chip select num is valid, but no device is attached
Currently -ENODEV is returned for both cases.
For the first case, it's more reasonable to return -EINVAL instead of
-ENODEV for invalid chip select numbers.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # SoPine
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
If an SPI controller driver does not implement ops->cs_info, that
probably means any chip select number could be valid, hence let's
return 0 for spi_cs_info().
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # SoPine
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Convert plain text documentation to reStructuredText format and add
it to Sphinx TOC tree. No essential content change.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
