As explained in commit 4af2a33ee5 ("cmd: gpio: Make `gpio input`
return pin value again") the `gpio input` is used in scripts to obtain
the value of a pin, despite the fact that CMD_RET_FAILURE is
indistinguishable from a valid pin value.
To be able to detect failures and properly use the value of a GPIO in
scripts we introduce the `gpio read` command that sets the variable
`name` to the value of the pin. Return code of the `gpio read` command
can be used to check for CMD_RET_SUCCESS or CMD_RET_FAILURE.
CONFIG_CMD_GPIO_READ is used to enable the `gpio read` command.
Signed-off-by: Diego Rondini <diego.rondini@kynetics.com>
4dbc107f46 ("cmd: gpio: Correct do_gpio() return value") correctly
changed the behaviour of the gpio command to return CMD_RET_SUCCESS or
CMD_RET_FAILURE, but any existing script which expects the return value
to be the pin value is broken by this change.
Reinstate the legacy behaviour for `gpio input` only.
Fixes: 4dbc107f46 ("cmd: gpio: Correct do_gpio() return value")
Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Signed-off-by: Alex Kiernan <alex.kiernan@hivehome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
