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

Boris Brezillon
2020-05-04T08:58:36Z

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).