usb: typec: fusb302: Refactor / simplify tcpm_set_cc()

usb: typec: fusb302: Refactor / simplify tcpm_set_cc()

After commit ea3b4d5523bc ("usb: typec: fusb302: Resolve fixed power role
contract setup"), tcpm_set_cc always calls fusb302_set_toggling.

Before this refactor tcpm_set_cc does the following:

1) fusb302_set_toggling(TOGGLING_MODE_OFF),
   this sets both FUSB_REG_MASK_BC_LVL and FUSB_REG_MASK_COMP_CHNG.
2) fusb302_set_cc_pull(...).
3) "reset cc status".
4) if pull-up fusb302_set_src_current(...).
5) if pull-up or pull-down enable bc-lvl resp comp-chng irq.
6) fusb302_set_toggling(new-toggling-mode), which again
   sets both FUSB_REG_MASK_BC_LVL and FUSB_REG_MASK_COMP_CHNG disabling
   the just enabled irq. fusb302_set_toggling is skipped when the new
   toggling mode is TOGGLING_MODE_OFF because this is already done in 1,
   note in this case 5) is a no-op.

When we are toggling the bits set by fusb302_set_cc_pull will be ignored
until we turn toggling off, so we can safely move the fusb302_set_cc_pull
call to before setting TOGGLING_MODE_OFF.

Either we are not toggling yet, or the src-current has already been set,
so we can also safely set the src-current earlier, allowing us to do the
fusb302_set_toggling(TOGGLING_MODE_OFF) call at the same time as we
set the other toggling modes. Also setting the src-current is a no-op
when not enabling pull-ups, so we can drop the if.

And since the second fusb302_set_toggling undoes the effects of step 5,
we can skip step 5, the bc-lvl resp comp-chng irq wil be enabled by
fusb302_handle_togdone_snk resp. fusb302_handle_togdone_src when toggling
is done.

Together this allows us to simplify things to:

1) fusb302_set_cc_pull(...)
2) "reset cc status"
3) fusb302_set_src_current(...)
4) fusb302_set_toggling(new-toggling-mode)

This commit does this, leading to a nice cleanup.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>