Re: [PATCH v4 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC

["Ramuthevar, Vadivel MuruganX" <vadivel.muruganx.ramuthevar@linux.intel.com>]

Hi Boris,

   Thank you very much for the prompt review and suggestions...

On 4/5/2020 3:08 pm, Boris Brezillon wrote:
> On Mon, 4 May 2020 10:02:35 +0800
> "Ramuthevar, Vadivel MuruganX"
> <vadivel.muruganx.ramuthevar@linux.intel.com>  wrote:
> 
>> Hi Boris,
>>
>> On 30/4/2020 9:01 pm, Boris Brezillon wrote:
>>> On Thu, 30 Apr 2020 14:36:00 +0200
>>> Boris Brezillon<boris.brezillon@collabora.com>  wrote:
>>>    
>>>> On Thu, 30 Apr 2020 17:07:03 +0800
>>>> "Ramuthevar, Vadivel MuruganX"
>>>> <vadivel.muruganx.ramuthevar@linux.intel.com>  wrote:
>>>>   
>>>>>>>> The question is, is it the same value we have in nand_pa or it is
>>>>>>>> different?
>>>>>>>>            
>>>>>>> Different address which is 0xE1400000 NAND_BASE_PHY address.
>>>>>> Then why didn't you tell me they didn't match when I suggested to pass
>>>>> sorry, because you keep asking nand_pa after that only I realized that.
>>>>>       
>>>>>> nand_pa? So now the question is, what does this address represent?
>>>>>                   EBU-MODULE
>>>>>     _________     _______________________
>>>>> |         |   |            |NAND CTRL  |
>>>>> | FPI BUS |==>| CS0(0x174) | 0xE100    ( 0xE14/0xE1C) NAND_PHY_BASE
>>>>> |_________|   |_CS1(0x17C)_|__________ |
>>>>>
>>>>> EBU_CONRTROLLER_BASE : 0xE0F0_0000
>>>>> HSNAND_BASE: 0xE100_0000
>>>>> NAND_CS0: 0xE140_0000
>>>>> NAND_CS1: 0xE1C0_0000
>>>>>
>>>>> MEM_REGION_BASE_CS0: 0x17400 (internal to ebu controller )
>>>>> MEM_REGION_BASE_CS1: 0x17C00
>>>>>       
>>>> Hm, I wonder if we shouldn't use a 'ranges' property to describe this
>>>> address translation. Something like
>>>>
>>>> 	ebu@xxx {
>>>> 		ranges = <0x17400000 0xe1400000 0x1000>,
>>>> 			 <0x17c00000 0xe1c00000 0x1000>;
>>>> 		reg = <0x17400000>, <0x17c00000>;
>>>> 		reg-names = "cs-0", "cs-1";
>>>> 	}
>>>>
>>>> The translated address (0xE1X00000) will be available in res->start,
>>>> and the non-translated one (0x17X00000) can be retrieved with
>>>> of_get_address(). All you'd have to do then would be calculate the
>>>> mask:
>>>>
>>>> 	mask = (translated_address & original_address) >> 22;
>>>> 	num_comp_bits = fls(mask);
>>>> 	WARN_ON(mask != GENMASK(num_comp_bits - 1, 0));
>>>>
>>>> Which allows you to properly set the ADDR_SEL() register without
>>>> relying on some hardcoded values:
>>>>
>>>> 	writel(original_address | EBU_ADDR_SEL_REGEN |
>>>> 	       EBU_ADDR_COMP_BITS(num_comp_bits),
>>>> 	       ebu_host->ebu + EBU_ADDR_SEL(csid));
>>>>
>>>> That's quite important if we want to merge the xway NAND driver with
>>>> this one.
>>> Looks like the translation is done at the FPI bus declaration level (see
>>> [1]). We really need to see the big picture to take a wise decision
>>> about the bindings. Would you mind pasting your dsti/dts files
>>> somewhere? It feels like the NAND controller is a sub-part of a more
>>> generic 'memory' controller, in which case the NAND controller should be
>>> declared as a child of this generic memory bus (called localbus in [1],
>>> but maybe EBU is more accurate).
>>>
>>> [1]https://github.com/xieyaxiongfly/Atheros_CSI_tool_OpenWRT_src/blob/master/target/linux/lantiq/files-4.14/arch/mips/boot/dts/vr9.dtsi#L162   
>>
>>    ebu_nand: ebu_nand@e0f00000 {
>>                    compatible = "intel,lgm-ebu-nand";
>>                    reg = <0xe0f00000 0x100
>>                    0xe1000000 0x300
>>                    0xe1400000 0x80000
>>                    0xe1c00000 0x10000>;
>>                    reg-names = "ebunand", "hsnand", "nand_cs0", nand_cs1";
>>                    dmas = <&dma0 8>, <&dma0 9>;
>>                    dma-names = "ebu_rx", "ebu_tx";
>>                    clocks =  <&cgu0 LGM_GCLK_EBU>;
>>            };
>>
>>
>> 	 &ebu_nand {
>> 	         status = "disabled";
>> 	        nand,cs = <1>;
>> 	        nand-ecc-mode = "hw";
>> 	        pinctrl-names = "default";
>> 	        pinctrl-0 = <&ebu_nand_base &ebu_cs1>;
>> 	};
>>
>>>    
> Ok. If I understand the SoC topology correctly it should actually be
> something like that:
> 
> {
> 	...
> 	fpi@xxxxx {
> 		compatible = "intel,lgm-fpi", "simple-bus";
> 
> 		/* You might have other ranges to define here */
> 		ranges = <0x16000000 0xe0000000 0x1000000>;
> 
> 		...

Sorry, we do not have fpi tree node in our dts/dtsi file instead we have 
the below one.. , that also not included the major peripherals 
controllers node.
         /* Special part from CPU core */
         core: core {
                 compatible = "intel,core", "simple-bus";
                 #address-cells = <1>;
                 #size-cells = <1>;
                 ranges;

                 ioapic1: interrupt-controller@fec00000 {
                         #interrupt-cells = <2>;
                         #address-cells = <0>;
                         compatible = "intel,ce4100-ioapic";
                         interrupt-controller;
                         reg = <0xfec00000 0x1000>;
                         nr_entries = <256>;
                 };

                 hpet: timer@fed00000 {
                         compatible = "intel,ce4100-hpet";
                         reg = <0xfed00000 0x400>;
                 };

                 lapic0: interrupt-controller@fee00000 {
                         compatible = "intel,ce4100-lapic";
                         reg = <0xfee00000 0x1000>;
                         no_pic_mode;
                 };
         };

other than this, rest all in independent node .

Thanks!

Regards
Vadivel