[U-Boot] [PATCH 1/2] arm: Add minimal support for Cortex-R5

[Michal Simek]

On 23.4.2018 05:53, Lokesh Vutla wrote:
> 
> 
> On Friday 20 April 2018 07:21 PM, Michal Simek wrote:
>> This minimal support will be used by Xilinx ZynqMP R5 cpu.
>>
>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>> ---
>>
>>  arch/arm/Kconfig              |  6 ++++++
>>  arch/arm/cpu/armv7r/Makefile  |  4 ++++
>>  arch/arm/cpu/armv7r/config.mk |  3 +++
>>  arch/arm/cpu/armv7r/cpu.c     | 24 ++++++++++++++++++++++++
>>  arch/arm/cpu/armv7r/start.S   | 17 +++++++++++++++++
>>  5 files changed, 54 insertions(+)
>>  create mode 100644 arch/arm/cpu/armv7r/Makefile
>>  create mode 100644 arch/arm/cpu/armv7r/config.mk
>>  create mode 100644 arch/arm/cpu/armv7r/cpu.c
>>  create mode 100644 arch/arm/cpu/armv7r/start.S
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index b5fbce03667d..b10804f55224 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -192,6 +192,10 @@ config CPU_V7M
>>  	select THUMB2_KERNEL
>>  	select SYS_CACHE_SHIFT_5
>>  
>> +config CPU_V7R
>> +	bool
>> +	select SYS_CACHE_SHIFT_6
> 
> select HAS_THUMB2 might be a good option?

I didn't enable it because I didn't test it.
It can be added when someone tests this.

> 
>> +
>>  config CPU_PXA
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> @@ -209,6 +213,7 @@ config SYS_CPU
>>  	default "arm1176" if CPU_ARM1176
>>  	default "armv7" if CPU_V7
>>  	default "armv7m" if CPU_V7M
>> +	default "armv7r" if CPU_V7R
>>  	default "pxa" if CPU_PXA
>>  	default "sa1100" if CPU_SA1100
>>  	default "armv8" if ARM64
>> @@ -223,6 +228,7 @@ config SYS_ARM_ARCH
>>  	default 6 if CPU_ARM1176
>>  	default 7 if CPU_V7
>>  	default 7 if CPU_V7M
>> +	default 7 if CPU_V7R
>>  	default 5 if CPU_PXA
>>  	default 4 if CPU_SA1100
>>  	default 8 if ARM64
> 
> I did a grep of CPU_V7, and you might want to update for CPU_V7R in the
> following places:
> 
> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> index 4fa8b38397..f4bc1f250d 100644
> --- a/arch/arm/Makefile
> +++ b/arch/arm/Makefile
> @@ -18,6 +18,7 @@ arch-$(CONFIG_CPU_ARM1136)	=-march=armv5
>  arch-$(CONFIG_CPU_ARM1176)	=-march=armv5t
>  arch-$(CONFIG_CPU_V7)		=$(call cc-option, -march=armv7-a, \
>  				 $(call cc-option, -march=armv7, -march=armv5))
> +arch-$(CONFIG_CPU_V7R)		=-march=armv7-r

I have setup PLATFORM_CPPFLAGS via config.mk

If both options are selected I am getting this compilation warning.
cc1: warning: switch -mcpu=cortex-r5 conflicts with -march=armv7-r switch

Not sure which one is better or if it is better to have this arch flag
via this makefile or as platform cppflags via config.mk.
I choose the second option because it seems to me better if this is in
subfolder. But not a problem to use different flag and put it to this
Makefile.

The same style is used for cpu_v7m.

>  arch-$(CONFIG_ARM64)		=-march=armv8-a
> 
>  # On Tegra systems we must build SPL for the armv4 core on the device
> @@ -41,6 +42,7 @@ tune-$(CONFIG_CPU_PXA)		=-mcpu=xscale
>  tune-$(CONFIG_CPU_ARM1136)	=
>  tune-$(CONFIG_CPU_ARM1176)	=
>  tune-$(CONFIG_CPU_V7)		=
> +tune-$(CONFIG_CPU_V7R)		=

Again as above. I used v7m as pattern and there is also empty tune
parameter. Is there any good reason to have it empty?

>  tune-$(CONFIG_ARM64)		=
> 
>  # Evaluate tune cc-option calls now
> 
> 
>> diff --git a/arch/arm/cpu/armv7r/Makefile b/arch/arm/cpu/armv7r/Makefile
>> new file mode 100644
>> index 000000000000..3c66976dfa62
>> --- /dev/null
>> +++ b/arch/arm/cpu/armv7r/Makefile
> 
> hmm..do we really need to create a separate folder? IIUC, the main
> difference between V7 and V7R is MMU vs MPU. IMHO, we should be able to
> get it using Kconfigs.

I have used V7 for the initial port and then was checking V7M which is
already there and used it as pattern for writing this patch.

I have debugged V7 and found that I need to disable CONFIG_HAS_VBAR
that's why I have created new symbol as for V7M.

Definitely I am open to hear your suggestions.

Thanks,
Michal