[1/2] dt-bindings: nand: meson: add Amlogic NAND controller driver

Message ID 20180613161314.14894-2-yixun.lan@amlogic.com
State New
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Series
  • mtd: rawnand: meson: add Amlogic NAND driver support
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Commit Message

Yixun Lan June 13, 2018, 4:13 p.m.
From: Liang Yang <liang.yang@amlogic.com>

Add Amlogic NAND controller dt-bindings for Meson SoC,
Current this driver support GXBB/GXL/AXG platform.

Signed-off-by: Liang Yang <liang.yang@amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
---
 .../bindings/mtd/amlogic,meson-nand.txt       | 118 ++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt

Comments

Martin Blumenstingl June 23, 2018, 10:46 p.m. | #1
Hello Yixun, Hello Liang,

I have a few small comments inline below
additionally I tried to explain the reason behind
"amlogic,mmc-syscon", clkin0 and clkin1 so Rob (or the devicetree
maintainers in general) can give feedback. feel free to correct me
wherever I'm wrong or provide additional notes in case I missed
something!

On Wed, Jun 13, 2018 at 10:17 AM Yixun Lan <yixun.lan@amlogic.com> wrote:
>
> From: Liang Yang <liang.yang@amlogic.com>
>
> Add Amlogic NAND controller dt-bindings for Meson SoC,
> Current this driver support GXBB/GXL/AXG platform.
>
> Signed-off-by: Liang Yang <liang.yang@amlogic.com>
> Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
> ---
>  .../bindings/mtd/amlogic,meson-nand.txt       | 118 ++++++++++++++++++
>  1 file changed, 118 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
>
> diff --git a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
> new file mode 100644
> index 000000000000..eac9f9433d5d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
> @@ -0,0 +1,118 @@
> +Amlogic NAND Flash Controller (NFC) for GXBB/GXL/AXG family SoCs
> +
> +This file documents the properties in addition to those available in
> +the MTD NAND bindings.
> +
> +Required properties:
> +- compatible : contains one of:
> +  - "amlogic,meson-gxl-nfc"
> +  - "amlogic,meson-axg-nfc"
the patch description states that GXBB/GXL/AXG are supported
shouldn't you add a compatible string for GXBB as well?

> +- clocks     :
> +       A list of phandle + clock-specifier pairs for the clocks listed
> +       in clock-names.
> +
> +- clock-names: Should contain the following:
> +       "core" - NFC module gate clock
> +       "clkin0" - Parent clock of internal mux
> +       "clkin1" - Other parent clock of internal mux
to give the devicetree maintainers some context on clkin0 and clkin1:

older SoCs (Meson8, Meson8b - not supported by this binding/driver
yet) had a dedicated NAND clock. there neither clkin0 or clkin1 would
be used, instead we just had a "nand" or "interface" clock (I'm not
aware of the actual naming in Amlogic's internal datasheets)

newer SoCs do NOT have a dedicated NAND "interface" clock anymore.
instead they are sharing the clock with the "sd_emmc_c" controller (I
*believe* the reason for this is because sd_emmc_c and the NAND
controller use the same pads on the SoC, pinctrl muxing controls where
these pads are routed -> NAND and sd_emmc_c cannot be used at the same
time, so SoC designers probably decided to re-use the clock)

unfortunately the sd_emmc_c clock is not provided by the "main" clock
controller on these newer SoCs
instead the clock is part of the MMC controller's register space (see
the SD_EMMC_CLOCK register in drivers/mmc/host/meson-gx-mmc.c)
even worse: the SD_EMMC_CLOCK contains more than just clock settings
(bit 25 enables the SDIO interrupt, which is currently not supported
by the meson-gx-mmc driver though)

the SD_EMMC_CLOCK register has a mux (CLK_SRC_MASK) to choose from
clkin0 and clkin1 which are passed here
the "amlogic,mmc-syscon" property is used to get a phandle to the
sd_emmc_c syscon register space
thus there is a bit of code duplication in the MMC and NAND drivers
with this binding (because both need to configure the SD_EMMC_CLOCK
register)

> +
> +- pins     : Select pins which NFC need.
> +- nand_pins: Detail NAND pins information.
> +               nand_pins: nand {
> +                       mux {
> +                               groups = "emmc_nand_d0",
> +                                       "emmc_nand_d1",
> +                                       "emmc_nand_d2",
> +                                       "emmc_nand_d3",
> +                                       "emmc_nand_d4",
> +                                       "emmc_nand_d5",
> +                                       "emmc_nand_d6",
> +                                       "emmc_nand_d7",
> +                                       "nand_ce0",
> +                                       "nand_rb0",
> +                                       "nand_ale",
> +                                       "nand_cle",
> +                                       "nand_wen_clk",
> +                                       "nand_ren_wr";
> +                               function = "nand";
> +                       };
> +               };
> +
> +- amlogic,mmc-syscon   : Required for NAND clocks, it's shared with SD/eMMC
> +                               controller port C
> +
> +Optional children nodes:
> +Children nodes represent the available nand chips.
> +
> +Optional properties:
> +- meson-nand-user-mode :
> +       only set 2 or 16 which mean the way of reading OOB bytes by NFC.
as far as I know vendor specific properties should follow the naming
schema "vendor,purpose"
in this case this would be "amlogic,nand-user-mode"

maybe Rob can comment on this?

> +- meson-nand-ran-mode :
> +       setting 0 or 1, means disable/enable scrambler which keeps the balence
> +       of 0 and 1
I assume 0 and 1 are the only possible values.
to use of_property_read_bool in the driver the property would be either:
- (absent) = scrambler is disabled
- amlogic,nand-enable-scrambler (without any value - also same comment
as above for the value) = scrambler is enabled


Regards
Martin
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Patch

diff --git a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
new file mode 100644
index 000000000000..eac9f9433d5d
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
@@ -0,0 +1,118 @@ 
+Amlogic NAND Flash Controller (NFC) for GXBB/GXL/AXG family SoCs
+
+This file documents the properties in addition to those available in
+the MTD NAND bindings.
+
+Required properties:
+- compatible : contains one of:
+  - "amlogic,meson-gxl-nfc"
+  - "amlogic,meson-axg-nfc"
+- clocks     :
+	A list of phandle + clock-specifier pairs for the clocks listed
+	in clock-names.
+
+- clock-names: Should contain the following:
+	"core" - NFC module gate clock
+	"clkin0" - Parent clock of internal mux
+	"clkin1" - Other parent clock of internal mux
+
+- pins     : Select pins which NFC need.
+- nand_pins: Detail NAND pins information.
+		nand_pins: nand {
+			mux {
+				groups = "emmc_nand_d0",
+					"emmc_nand_d1",
+					"emmc_nand_d2",
+					"emmc_nand_d3",
+					"emmc_nand_d4",
+					"emmc_nand_d5",
+					"emmc_nand_d6",
+					"emmc_nand_d7",
+					"nand_ce0",
+					"nand_rb0",
+					"nand_ale",
+					"nand_cle",
+					"nand_wen_clk",
+					"nand_ren_wr";
+				function = "nand";
+			};
+		};
+
+- amlogic,mmc-syscon	: Required for NAND clocks, it's shared with SD/eMMC
+				controller port C
+
+Optional children nodes:
+Children nodes represent the available nand chips.
+
+Optional properties:
+- meson-nand-user-mode :
+	only set 2 or 16 which mean the way of reading OOB bytes by NFC.
+- meson-nand-ran-mode :
+	setting 0 or 1, means disable/enable scrambler which keeps the balence
+	of 0 and 1
+
+Other properties:
+see Documentation/devicetree/bindings/mtd/nand.txt for generic bindings.
+
+Example demonstrate on AXG SoC:
+
+	sd_emmc_c: mmc@7000 {
+		compatible = "simple-bus", "syscon";
+		reg = <0x0 0x7000 0x0 0x800>;
+		status = "okay";
+	};
+
+	nand: nfc@7800 {
+		compatible = "amlogic,meson-axg-nfc";
+		reg = <0x0 0x7800 0x0 0x100>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		interrupts = <GIC_SPI 34 IRQ_TYPE_EDGE_RISING>;
+		status = "disabled";
+		clocks = <&clkc CLKID_SD_EMMC_C>,
+				<&clkc CLKID_SD_EMMC_C_CLK0>,
+				<&clkc CLKID_FCLK_DIV2>;
+		clock-names = "core", "clkin0", "clkin1";
+		amlogic,mmc-syscon = <&sd_mmc_c>;
+
+		status = "okay";
+
+		pinctrl-names = "default";
+		pinctrl-0 = <&nand_pins>;
+
+		nand@0 {
+			reg = <0>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			nand-on-flash-bbt;
+			nand-ecc-mode = "hw";
+			nand-ecc-strength = <8>;
+			nand-ecc-step-size = <1024>;
+
+			meson-nand-user-mode = <2>;
+			meson-nand-ran-mode = <1>;
+
+			partition@0 {
+				label = "boot";
+				reg = <0x00000000 0x00200000>;
+				read-only;
+			};
+			partition@200000 {
+				label = "env";
+				reg = <0x00200000 0x00400000>;
+			};
+			partition@600000 {
+				label = "system";
+				reg = <0x00600000 0x00a00000>;
+			};
+			partition@1000000 {
+				label = "rootfs";
+				reg = <0x01000000 0x03000000>;
+			};
+			partition@4000000 {
+				label = "media";
+				reg = <0x04000000 0x8000000>;
+			};
+		};
+	};