Re: [PATCH] ARM: zynq: Add OCM driver

[Michal Simek]

On 03/17/2014 05:48 AM, Olof Johansson wrote:
> On Wed, Mar 12, 2014 at 01:00:51PM +0100, Michal Simek wrote:
>> Hi Olof,
>>
>>>> diff --git a/Documentation/devicetree/bindings/arm/zynq/xlnx,zynq-ocm.txt b/Documentation/devicetree/bindings/arm/zynq/xlnx,zynq-ocm.txt
>>>> new file mode 100644
>>>> index 0000000..64cb5e8
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/arm/zynq/xlnx,zynq-ocm.txt
>>>> @@ -0,0 +1,17 @@
>>>> +Device tree bindings for Zynq's OCM
>>>> +
>>>> +The OCM is divided to 4 64kB segments which can be separately configured
>>>> +to low or high location. Location is controlled via SLCR.
>>>> +
>>>> +Required properties:
>>>> + compatible: Compatibility string. Must be "xlnx,zynq-ocm-1.0".
>>>> + reg: Specify the base and size of the OCM registers in the memory map.
>>>> +      E.g.: reg = <0xf800c000 0x1000>;
>>>> +
>>>> +Example:
>>>> +ocmc: ocmc@f800c000 {
>>>> +       compatible =  "xlnx,zynq-ocm-1.0";
>>>> +       interrupt-parent = <&intc>;
>>>> +       interrupts = <0 3 4>;
>>>> +       reg = <0xf800c000 0x1000>;
>>>> +} ;
>>>> diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
>>>> index 1d942e2..4929be5 100644
>>>> --- a/arch/arm/boot/dts/zynq-7000.dtsi
>>>> +++ b/arch/arm/boot/dts/zynq-7000.dtsi
>>>> @@ -66,6 +66,13 @@
>>>>                         cache-level = <2>;
>>>>                 };
>>>>
>>>> +               ocmc: ocmc@f800c000 {
>>>> +                       compatible = "xlnx,zynq-ocm-1.0";
>>>> +                       interrupt-parent = <&intc>;
>>>> +                       interrupts = <0 3 4>;
>>>> +                       reg = <0xf800c000 0x1000>;
>>>> +               } ;
>>>> +
>>>>                 uart0: uart@e0000000 {
>>>>                         compatible = "xlnx,xuartps";
>>>>                         status = "disabled";
>>>> diff --git a/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
>>>> index 323e505..f3e6ce4 100644
>>>> --- a/arch/arm/mach-zynq/Kconfig
>>>> +++ b/arch/arm/mach-zynq/Kconfig
>>>> @@ -15,5 +15,6 @@ config ARCH_ZYNQ
>>>>         select CADENCE_TTC_TIMER
>>>>         select ARM_GLOBAL_TIMER
>>>>         select MFD_SYSCON
>>>> +       select GENERIC_ALLOCATOR
>>>>         help
>>>>           Support for Xilinx Zynq ARM Cortex A9 Platform
>>>> diff --git a/arch/arm/mach-zynq/Makefile b/arch/arm/mach-zynq/Makefile
>>>> index 1b25d92..626f64b 100644
>>>> --- a/arch/arm/mach-zynq/Makefile
>>>> +++ b/arch/arm/mach-zynq/Makefile
>>>> @@ -3,7 +3,7 @@
>>>>  #
>>>>
>>>>  # Common support
>>>> -obj-y                          := common.o slcr.o
>>>> +obj-y                          := common.o slcr.o zynq_ocm.o
>>>>  CFLAGS_REMOVE_hotplug.o                =-march=armv6k
>>>>  CFLAGS_hotplug.o               =-Wa,-march=armv7-a -mcpu=cortex-a9
>>>>  obj-$(CONFIG_HOTPLUG_CPU)      += hotplug.o
>>>> diff --git a/arch/arm/mach-zynq/common.h b/arch/arm/mach-zynq/common.h
>>>> index b097844..953f6a1 100644
>>>> --- a/arch/arm/mach-zynq/common.h
>>>> +++ b/arch/arm/mach-zynq/common.h
>>>> @@ -24,6 +24,7 @@ extern int zynq_early_slcr_init(void);
>>>>  extern void zynq_slcr_system_reset(void);
>>>>  extern void zynq_slcr_cpu_stop(int cpu);
>>>>  extern void zynq_slcr_cpu_start(int cpu);
>>>> +extern u32 zynq_slcr_get_ocm_config(void);
>>>>
>>>>  #ifdef CONFIG_SMP
>>>>  extern void secondary_startup(void);
>>>> diff --git a/arch/arm/mach-zynq/slcr.c b/arch/arm/mach-zynq/slcr.c
>>>> index c1f1499..9a37ab3 100644
>>>> --- a/arch/arm/mach-zynq/slcr.c
>>>> +++ b/arch/arm/mach-zynq/slcr.c
>>>> @@ -26,6 +26,7 @@
>>>>  #define SLCR_PS_RST_CTRL_OFFSET                0x200 /* PS Software Reset Control */
>>>>  #define SLCR_A9_CPU_RST_CTRL_OFFSET    0x244 /* CPU Software Reset Control */
>>>>  #define SLCR_REBOOT_STATUS_OFFSET      0x258 /* PS Reboot Status */
>>>> +#define SLCR_OCM_CFG_OFFSET            0x910 /* OCM Address Mapping */
>>>>
>>>>  #define SLCR_UNLOCK_MAGIC              0xDF0D
>>>>  #define SLCR_A9_CPU_CLKSTOP            0x10
>>>> @@ -107,6 +108,20 @@ void zynq_slcr_system_reset(void)
>>>>  }
>>>>
>>>>  /**
>>>> + * zynq_slcr_get_ocm_config - Get SLCR OCM config
>>>> + *
>>>> + * return:     OCM config bits
>>>> + */
>>>> +u32 zynq_slcr_get_ocm_config(void)
>>>> +{
>>>> +       u32 val;
>>>> +
>>>> +       zynq_slcr_read(&val, SLCR_OCM_CFG_OFFSET);
>>>> +
>>>> +       return val;
>>>> +}
>>>> +
>>>> +/**
>>>>   * zynq_slcr_cpu_start - Start cpu
>>>>   * @cpu:       cpu number
>>>>   */
>>>> diff --git a/arch/arm/mach-zynq/zynq_ocm.c b/arch/arm/mach-zynq/zynq_ocm.c
>>>> new file mode 100644
>>>> index 0000000..034a65b
>>>> --- /dev/null
>>>> +++ b/arch/arm/mach-zynq/zynq_ocm.c
>>>> @@ -0,0 +1,243 @@
>>>> +/*
>>>> + * Copyright (C) 2013 Xilinx
>>>> + *
>>>> + * Based on "Generic on-chip SRAM allocation driver"
>>>
>>> We're not adding new drivers under arch/arm, so if you need this
>>> driver then you should either merge it under drivers/ somewhere, or
>>> look at extending the generic driver in a way that you can reuse it.
>>
>> Driver is reusing ideas from this generic driver but
>> incorporation our changes to will be problematic.
>>
>> It is a shame that you didn't review the rest of code below.
>> The reason why I have added this driver to arch/arm/mach-zynq
>> was that there is code connection to zynq SMP bootup trampoline
>> which has to be added at 0x0 when OCM is placed at 0x0.
>> And this memory can't be used for generic purpose.
>> If you see any nice way how to it please let me know.
> 
> Rockchip just went through some of the same discussions -- they need to
> use onchip SRAM for SMP spin-up. You should look at that patchset and
> see if you can solve it in a similar manner, the needs seem to be quite
> similar.

I found that
http://www.spinics.net/lists/arm-kernel/msg310761.html
it is definitely good starting point. Thanks for that.

The solution which I have in my mind because of autodetection
via slcr is to build up that node in zynq code from controller
and support ranges in node just because of not copy that node
in worst case 4 times.

               sram: sram@0 {
                       compatible = "mmio-sram";
                       reg = <0x0 0x20000 0xfffe0000 0x20000>;
                       #address-cells = <1>;
                       #size-cells = <1>;
                       ranges;

                       smp-sram@0 {
                               compatible = "xlnx,zynq-smp-sram";
                               reg = <0x0 0x50>;
                       };
               };

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform

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