[U-Boot] [PATCH] imx: mx7: psci: Add support for version command

[Stefan Agner <stefan@agner.ch>]

On 31.05.2018 20:13, Trent Piepho wrote:
> This command should be supported for PSCI 1.0.  Current code results in
> this message from the kernel:  "PSCIv65535.65535 detected in firmware."
> 
> This will mess up a kernel check of the PSCI version.  Currently the
> kernel only cares if the version is at least 1.0 so it doesn't break
> anything, as the incorrect version and correct version are both >= 1.0,
> but as soon as a check for > 1.0 goes in it will fail.

The right direction, it can also be done in C though:

unsigned int __secure psci_version(u32 function_id)
{
	return ARM_PSCI_VER_1_0;
}

But this is not complete though, since also other callbacks need to be
supported for proper PSCI 1.0 support.

See also this discussion:
https://www.spinics.net/lists/arm-kernel/msg640337.html

I try to come up with a proper fix for this.

--
Stefan

> 
> CC: Anson Huang <Anson.Huang@nxp.com>
> Cc: Fabio Estevam <fabio.estevam@nxp.com>
> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Stefano Babic <sbabic@denx.de>
> Signed-off-by: Trent Piepho <tpiepho@impinj.com>
> ---
>  arch/arm/mach-imx/mx7/psci.S | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/mx7/psci.S b/arch/arm/mach-imx/mx7/psci.S
> index 89dcf880e8..7035f6093b 100644
> --- a/arch/arm/mach-imx/mx7/psci.S
> +++ b/arch/arm/mach-imx/mx7/psci.S
> @@ -57,4 +57,14 @@ psci_system_off:
>  3: 	wfi
>  	b 3b
>  
> +.globl psci_version
> +psci_version:
> +#if defined(CONFIG_ARMV7_PSCI_1_0)
> +	ldr	r0, =ARM_PSCI_VER_1_0
> +#else
> +#error "add support for your PSCI version"
> +#endif
> +
> +	bx	lr
> +
>  	.popsection