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

Boris Brezillon
2020-05-04T07:08:32Z

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";
}
}
}
}
}