commands/*: Replace license and copyright boilerplate by SPDX identfiers ...

While at it also drop references to the non-existing CREDITS file and do
some small rearrangements for some uniform formatting.
(SPDX-License-Identifier first, then copyright texts and then an empty
line.)

The advantage is that these specifiers are machine-parseable which helps
license conformance.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: smc: make command usable when ARM_PSCI is undefined ...

The smc command can be useful whenever PSCI is used, regardless of
whether barebox provides the secure monitor or not. Have it depend
on ARM_SMCCC instead.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: smc: verify PSCI_POWER_ON with interprocessor handshake ...

The use of psci_printf here, at least for the phytec-phycore-imx7,
is racy, because access to the UART is not synchronized. This may
lead to characters being swallowed and most certainly to garbled
text. One way around this would be using separate UART ports for
each core or even more generically, just dropping psci_printf and
resorting to inter-core communication over shared-memory to check
whether code execution succeeded.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: psci: make locally-used function static ...

Fixes a warning that the function is global, but without prototype.
No functional change.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: psci: properly wire in command help ...

This was supposed to happen in 9efa1f8b ("ARM: psci: wire in smc command
help") along with some other changes. After rebases, the other changes
remained but this one was lost.. Do this right this time and specify the
appropriate BAREBOX_CMD_HELP.

Fixes: 9efa1f8b ("ARM: psci: wire in smc command help")
Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: psci: factor out smc command into commands/ ...

So far, the smc command was only usable when barebox also provides the
secure monitor. It's useful to have it when barebox is a PSCI consumer
as well to test whether the secure monitor works.
Factor out the code into commands/ in preparation to do so.
No functional change.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>