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 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>;

		...

		ebu@xxxx {
			compatible = "intel,lgm-ebu", "simple-bus";
			ranges;
			pinctrl-names = "default";
			pinctrl-0 = <&ebu_nand_base &ebu_cs1>;

			/*
			 * Add your PCI and NOR controller definitions
			 * here.
			 */
			...
			
			nand-controller@16f00000 {
				compatible = "intel,lgm-ebu-nand-controller";
				reg = <0x16f00000 0x100>,
				      <0x17000000 0x300>,
				      <0x17400000 0x80000>,
				      <0x17c00000 0x10000>;
				reg-names = "ebunand", "hsnand",
					     "cs0", cs1";
				#address-cells = <1>;
				#size-cells = <0>;

				/*
				 * I'm not sure if those belong here: if the
				 * DMA channels and clocks are shared by all
				 * controllers attached to the EBU they should
				 * be moved to the EBU node.
				 */
				dmas = <&dma0 8>, <&dma0 9>;
				dma-names = "rx", "tx";
				clocks =  <&cgu0 LGM_GCLK_EBU>;

				nand@1 {
					reg = <1>;
					nand-ecc-mode = "hw";
				}
			}
		}
	}
}