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

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 4 May 2020 16:50:08 +0800
"Ramuthevar, Vadivel MuruganX"
<vadivel.muruganx.ramuthevar@linux.intel.com> wrote:

> 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.

Duh, not sure that's a good idea to hide that, especially since you
have to describe the address translation that happens when crossing the
FPI bus (the ranges thing I mentioned previously).