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Reply-To: vadivel.muruganx.ramuthevar@linux.intel.com
Subject: Re: [PATCH v4 2/2] mtd: rawnand: Add NAND controller support on Intel
 LGM SoC
To:     Boris Brezillon <boris.brezillon@collabora.com>,
        tglx@linutronix.de, cheol.yong.kim@intel.com,
        devicetree@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, masonccyang@mxic.com.tw,
        anders.roxell@linaro.org, vigneshr@ti.com, arnd@arndb.de,
        hauke.mehrtens@intel.com, richard@nod.at,
        brendanhiggins@google.com, linux-mips@vger.kernel.org,
        robh+dt@kernel.org, linux-mtd@lists.infradead.org,
        miquel.raynal@bootlin.com, qi-ming.wu@intel.com,
        andriy.shevchenko@intel.com
References: <20200429104205.18780-1-vadivel.muruganx.ramuthevar@linux.intel.com>
 <20200429104205.18780-3-vadivel.muruganx.ramuthevar@linux.intel.com>
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From:   "Ramuthevar, Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
Message-ID: <db023399-8b4d-c75c-30c8-b35e38e2e5f8@linux.intel.com>
Date:   Mon, 4 May 2020 16:50:08 +0800
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Hi Boris,

On 4/5/2020 3:17 pm, Boris Brezillon wrote:
> On Mon, 4 May 2020 15:15:08 +0800
> "Ramuthevar, Vadivel MuruganX"
> <vadivel.muruganx.ramuthevar@linux.intel.com> wrote:
> 
>> 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 .
> 
> But you do have an FPI bus, right? If this is the case it should be
> represented.

Yes, FPI bus is slave to core which connects all the peripherals.

  Or is the "intel,core" bus actually the FPI bus that you
> named differently?

FPI slave bus connects to core bus by OCP bridge, so here it is named 
FPI bus, but SW perspective didn't have root tree which has all 
sub-nodes, as of now each peripheral has its own node.

Regards
Vadivel
>