[U-Boot] [PATCH V4 2/3] mx7: psci: add basic psci support

[Gary Bisson]

Hi Peng,

On Thu, Mar 31, 2016 at 3:33 PM, Peng Fan <van.freenix at gmail.com> wrote:
> Hi Gary,
>
> On Thu, Mar 31, 2016 at 01:17:07PM +0200, Gary Bisson wrote:
>>Hi all,
>>
>>Sorry to revive an old thread but I have some questions about thit patch.
>>
>>On Fri, Oct 23, 2015 at 10:13:04AM +0800, Peng Fan wrote:
>>> 1. add basic psci support for imx7 chip.
>>> 2. support cpu_on and cpu_off.
>>> 3. switch to non-secure mode when boot linux kernel.
>>> 4. set csu allow accessing all peripherial register in non-secure mode.
>>>
>>> Signed-off-by: Frank Li <Frank.Li at freescale.com>
>>> Signed-off-by: Peng Fan <Peng.Fan at freescale.com>
>>> Cc: Stefano Babic <sbabic at denx.de>
>>> Cc: Fabio Estevam <fabio.estevam at freescale.com>
>>> ---
>>> [snip]
>>> diff --git a/arch/arm/include/asm/arch-mx7/imx-regs.h b/arch/arm/include/asm/arch-mx7/imx-regs.h
>>> index 4dc11ee..9213374 100644
>>> --- a/arch/arm/include/asm/arch-mx7/imx-regs.h
>>> +++ b/arch/arm/include/asm/arch-mx7/imx-regs.h
>>> @@ -866,6 +866,9 @@ struct cspi_regs {
>>>      ECSPI3_BASE_ADDR, \
>>>      ECSPI4_BASE_ADDR
>>>
>>> +#define CSU_INIT_SEC_LEVEL0 0x00FF00FF
>>> +#define CSU_NUM_REGS                64
>>
>>In the security documentation (revA) it is said that there are 40 CSL,
>>why is it 64 here?
>>
>>Also, although this seems to work, later on when the kernel boots I get
>>the following CAAM errors:
>>caam 30900000.caam: failed to acquire DECO 0
>>...
>>caam 30900000.caam: failed to acquire DECO 0
>>caam 30900000.caam: failed to instantiate RNG
>>caam: probe of 30900000.caam failed with error -11
>
> This patch will let SoC switch to non sec mode. I have little knowledge
> of CAAM, I guess it works in sec mode. So when kernel boots up, it will
> complains a lot...

Seems like a safe assumption to say CAAM requires to be run in secure mode.

>>If I revert this patch and therefore leave the CSU to its default state
>>at bootup the above CAAM issue disappears, do you have any idea why?
>
>
> Revert this patch, then all code runs in sec mode.
>
>>
>>As a FYI, I am using U-Boot v2016.03 + a few patches that adds support
>>for our i.MX7 Nitrogen7 board. You can find the repo here:
>>https://github.com/boundarydevices/u-boot-imx6/tree/boundary-v2016.03
>>
>>Also, if I base U-Boot on top of NXP repo it works too since this csu/psci
>>support isn't there:
>>http://git.freescale.com/git/cgit.cgi/imx/uboot-imx.git/tree/?id=rel_imx_3.14.52_1.1.0_ga
>
> Yeah. NXP code not switch to non sec mode.
>
> You can revert this patch in your vendor tree. I am not sure whether you
> have tested linux upstream tree, or you use caam code from NXP vendor
> tree. If you use NXP vendor tree, and use uboot upstream code, sure
> caam will complain errros. We would like to use PSCI and work in
> non-sec mode, but still some works need to be done.

Thanks for your feedback. We are using our own tree based on NXP
vendor one (3.14.52_1.1.0_ga).

We usually use upstream U-Boot with this kernel tree. I guess the
easiest option here is actually to add CONFIG_MX7_SEC to our board
config, this avoids to revert the patches.

Thanks,
Gary