Re: [PATCH 2/3] dt-bindings: arm: amlogic: Add SoC information bindings

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On 04/04/2017 02:26 PM, Rob Herring wrote:
> On Tue, Apr 4, 2017 at 3:51 AM, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
>> On 04/03/2017 06:34 PM, Rob Herring wrote:
>>> On Fri, Mar 31, 2017 at 04:10:30PM +0200, Neil Armstrong wrote:
>>>> On 03/31/2017 03:44 PM, Arnd Bergmann wrote:
>>>>> On Fri, Mar 31, 2017 at 10:47 AM, Neil Armstrong
>>>>> <narmstrong@xxxxxxxxxxxx> wrote:
>>>>>> Add bindings for the SoC information register of the Amlogic SoCs.
>>>>>>
>>>>>> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>>>>>> ---
>>>>>>  Documentation/devicetree/bindings/arm/amlogic.txt | 20 ++++++++++++++++++++
>>>>>>  1 file changed, 20 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/arm/amlogic.txt b/Documentation/devicetree/bindings/arm/amlogic.txt
>>>>>> index bfd5b55..b850985 100644
>>>>>> --- a/Documentation/devicetree/bindings/arm/amlogic.txt
>>>>>> +++ b/Documentation/devicetree/bindings/arm/amlogic.txt
>>>>>> @@ -52,3 +52,23 @@ Board compatible values:
>>>>>>    - "amlogic,q201" (Meson gxm s912)
>>>>>>    - "nexbox,a95x" (Meson gxbb or Meson gxl s905x)
>>>>>>    - "nexbox,a1" (Meson gxm s912)
>>>>>> +
>>>>>> +Amlogic Meson GX SoCs Information
>>>>>> +----------------------------------
>>>>>> +
>>>>>> +The Meson SoCs have a Product Register that allows to retrieve SoC type,
>>>>>> +package and revision information. If present, a device node for this register
>>>>>> +should be added.
>>>>>> +
>>>>>> +Required properties:
>>>>>> +  - compatible: For Meson GX SoCs, must be "amlogic,meson-gx-socinfo".
>>>>>> +  - reg: Base address and length of the register block.
>>>>>> +
>>>>>> +Examples
>>>>>> +--------
>>>>>> +
>>>>>> +       chipid@220 {
>>>>>> +               compatible = "amlogic,meson-gx-socinfo";
>>>>>> +               reg = <0x0 0x00220 0x0 0x4>;
>>>>>> +       };
>>>>>> +
>>>>>
>>>>> The register location would hint that this is in the middle of some block of
>>>>> random registers, i.e. a syscon or some unrelated device.
>>>>>
>>>>> Are you sure that "socinfo" is the actual name of the IP block and that
>>>>> it only has a single 32-bit register?
>>>>>
>>>>>      Arnd
>>>>>
>>>>
>>>> Hi Arnd,
>>>>
>>>> I'm sorry I did not find any relevant registers in the docs or source code describing
>>>> it in a specific block of registers, and no close enough register definitions either.
>>>> They may be used by the secure firmware I imagine.
>>>>
>>>> For the register name, Amlogic refers it to "cpu_version" in their code, but it really
>>>> gives some details on the whole SoC and package, and socinfo seems better.
>>>
>>> A register at address 0x220 seems a bit strange (unless there's ranges
>>> you're not showing), but ROM code at this address would be fairly
>>> typical. And putting version information into the ROM is also common.
>>>
>>> Rob
>>>
>>
>> Hi Rob.
>>
>> Indeed it's part of a larger range :
>>                  aobus: aobus@c8100000 {
>>                         compatible = "simple-bus";
>>                         reg = <0x0 0xc8100000 0x0 0x100000>;
>>                         #address-cells = <2>;
>>                         #size-cells = <2>;
>>                         ranges = <0x0 0x0 0x0 0xc8100000 0x0 0x100000>;
>>
>>
>> While scrubbing on the uboot source, I found a sort of block of registers dedicated to communicate with
>> the secure firmware :
>> AO_SEC_REG0                                                     0x140
>> AO_SEC_REG1                                                     0x144
>> AO_SEC_REG2                                                     0x148
>> AO_SEC_TMODE_PWD0                                               0x160
>> AO_SEC_TMODE_PWD1                                               0x164
>> AO_SEC_TMODE_PWD2                                               0x168
>> AO_SEC_TMODE_PWD3                                               0x16C
>> AO_SEC_SCRATCH                                                  0x17C
>> AO_SEC_JTAG_PWD0                                                0x180
>> AO_SEC_JTAG_PWD1                                                0x184
>> AO_SEC_JTAG_PWD2                                                0x188
>> AO_SEC_JTAG_PWD3                                                0x18C
>> AO_SEC_JTAG_SEC_CNTL                                            0x190
>> AO_SEC_JTAG_PWD_ADDR0                                           0x194
>> AO_SEC_JTAG_PWD_ADDR1                                           0x198
>> AO_SEC_JTAG_PWD_ADDR2                                           0x19C
>> AO_SEC_JTAG_PWD_ADDR3                                           0x1A0
>> AO_SEC_SHARED_AHB_SRAM_REG0_0                                   0x1C0
>> AO_SEC_SHARED_AHB_SRAM_REG0_1                                   0x1C4
>> AO_SEC_SHARED_AHB_SRAM_REG0_2                                   0x1C8
>> AO_SEC_SHARED_AHB_SRAM_REG1_0                                   0x1CC
>> AO_SEC_SHARED_AHB_SRAM_REG1_1                                   0x1D0
>> AO_SEC_SHARED_AHB_SRAM_REG1_2                                   0x1D4
>> AO_SEC_SHARED_AHB_SRAM_REG2_0                                   0x1D8
>> AO_SEC_SHARED_AHB_SRAM_REG2_1                                   0x1DC
>> AO_SEC_SHARED_AHB_SRAM_REG2_2                                   0x1E0
>> AO_SEC_SHARED_AHB_SRAM_REG3_0                                   0x1E4
>> AO_SEC_SHARED_AHB_SRAM_REG3_1                                   0x1E8
>> AO_SEC_SHARED_AHB_SRAM_REG3_2                                   0x1EC
>> AO_SEC_AO_AHB_SRAM_REG0_0                                       0x1F0
>> AO_SEC_AO_AHB_SRAM_REG0_1                                       0x1F4
>> AO_SEC_AO_AHB_SRAM_REG1_0                                       0x1F8
>> AO_SEC_AO_AHB_SRAM_REG1_1                                       0x1FC
>> AO_SEC_SD_CFG8                                                  0x220
>> AO_SEC_SD_CFG9                                                  0x224
>> AO_SEC_SD_CFG10                                                 0x228
>> AO_SEC_SD_CFG11                                                 0x22C
>> AO_SEC_SD_CFG12                                                 0x230
>> AO_SEC_SD_CFG13                                                 0x234
>> AO_SEC_SD_CFG14                                                 0x238
>> AO_SEC_SD_CFG15                                                 0x23C
>> AO_SEC_GP_CFG0                                                  0x240
>> AO_SEC_GP_CFG1                                                  0x244
>> AO_SEC_GP_CFG2                                                  0x248
>> AO_SEC_GP_CFG3                                                  0x24C
>> AO_SEC_GP_CFG4                                                  0x250
>> AO_SEC_GP_CFG5                                                  0x254
>> AO_SEC_GP_CFG6                                                  0x258
>> AO_SEC_GP_CFG7                                                  0x25C
>> AO_SEC_GP_CFG8                                                  0x260
>> AO_SEC_GP_CFG9                                                  0x264
>> AO_SEC_GP_CFG10                                                 0x268
>> AO_SEC_GP_CFG11                                                 0x26C
>> AO_SEC_GP_CFG12                                                 0x270
>> AO_SEC_GP_CFG13                                                 0x274
>> AO_SEC_GP_CFG14                                                 0x278
>> AO_SEC_GP_CFG15                                                 0x27C
>>
>>
>> As you see, the register we use here is AO_SEC_SD_CFG8...
>>
>> Should I define all this block as simple-mfd and refer to it as a regmap ?
>>
>> aobus: aobus@c8100000 {
>>         compatible = "simple-bus";
>>         reg = <0x0 0xc8100000 0x0 0x100000>;
>>         #address-cells = <2>;
>>         #size-cells = <2>;
>>         ranges = <0x0 0x0 0x0 0xc8100000 0x0 0x100000>;
>>
>>         ao_secure: ao-secure@140 {
>>                 compatible = "amlogic,meson-gx-ao-secure", "simple-mfd";
>>                 reg = <0x0 0x140 0x0 0x140>;
>>         };
>> };
>>
>> chipid {
>>         compatible = "amlogic,meson-gx-socinfo";
>>         ao-secure = <&ao_secure>;
>>         chip-info-reg = <0xe0>;
> 
> Why even divide it up further in DT? IMO, describing single
> registers/address in DT is too fine grained.
> 
> Rob
> 

Rob, I don't get it.

Maybe something like that ?

aobus: aobus@c8100000 {
        compatible = "simple-bus";
        reg = <0x0 0xc8100000 0x0 0x100000>;
        #address-cells = <2>;
        #size-cells = <2>;
        ranges = <0x0 0x0 0x0 0xc8100000 0x0 0x100000>;

        ao_secure: ao-secure@140 {
                compatible = "amlogic,meson-gx-ao-secure", "simple-mfd", "simple-bus";
                reg = <0x0 0x140 0x0 0x140>;
		#address-cells = <1>;
		#size-cells = <1>;

		chipid@e0 {
        		compatible = "amlogic,meson-gx-socinfo";
			reg = <0xe0 0x4>;
        	};
	};
};

Concerning the fine graining, I'm sorry but the actual information comes from a single register here...

Neil
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