Re: [PATCH v1 12/30] dt-bindings: reset: Add starfive,jh7110-reset bindings

[Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu, 29 Sep 2022 13:43:49 -0500, Rob Herring wrote:
> On Fri, Sep 30, 2022 at 01:51:47AM +0800, Hal Feng wrote:
> > Add bindings for the reset controller on the JH7110 RISC-V
> > SoC by StarFive Technology Ltd.
> > 
> > Signed-off-by: Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> >  .../bindings/reset/starfive,jh7110-reset.yaml | 54 +++++++++++++++++++
> >  1 file changed, 54 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml b/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
> > new file mode 100644
> > index 000000000000..bb0010c200f9
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
> > @@ -0,0 +1,54 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/reset/starfive,jh7110-reset.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: StarFive JH7110 SoC Reset Controller Device Tree Bindings
> > +
> > +maintainers:
> > +  - Emil Renner Berthing <kernel@xxxxxxxx>
> > +  - Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - starfive,jh7110-reset
> 
> 'reg' needed? Is this a sub-block of something else?

Yes, the reset node is a child node of the syscon node, see patch 27 for detail.
You might not see the complete patches at that time due to technical issue of
our smtp email server. Again, I feel so sorry about that.

	syscrg: syscrg@13020000 {
		compatible = "syscon", "simple-mfd";
		reg = <0x0 0x13020000 0x0 0x10000>;

		syscrg_clk: clock-controller@13020000 {
			compatible = "starfive,jh7110-clkgen-sys";
			clocks = <&osc>, <&gmac1_rmii_refin>,
				 <&gmac1_rgmii_rxin>,
				 <&i2stx_bclk_ext>, <&i2stx_lrck_ext>,
				 <&i2srx_bclk_ext>, <&i2srx_lrck_ext>,
				 <&tdm_ext>, <&mclk_ext>;
			clock-names = "osc", "gmac1_rmii_refin",
				"gmac1_rgmii_rxin",
				"i2stx_bclk_ext", "i2stx_lrck_ext",
				"i2srx_bclk_ext", "i2srx_lrck_ext",
				"tdm_ext", "mclk_ext";
			#clock-cells = <1>;
		};

		syscrg_rst: reset-controller@13020000 {
			compatible = "starfive,jh7110-reset";
			#reset-cells = <1>;
			starfive,assert-offset = <0x2F8>;
			starfive,status-offset= <0x308>;
			starfive,nr-resets = <JH7110_SYSRST_END>;
		};
	};

In this case, we get the memory mapped space through the parent node with syscon
APIs. You can see patch 13 for detail.

static int reset_starfive_register(struct platform_device *pdev, const u32 *asserted)
{
	struct starfive_reset *data;
	int ret;

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->regmap = device_node_to_regmap(pdev->dev.of_node);		  //for JH7100
	if (IS_ERR(data->regmap)) {
		data->regmap = syscon_node_to_regmap(pdev->dev.of_node->parent);  //for JH7110
		if (IS_ERR(data->regmap)) {
			dev_err(&pdev->dev, "failed to get regmap (error %ld)\n",
				PTR_ERR(data->regmap));
			return PTR_ERR(data->regmap);
		}
	}
	...
}

We use this method to avoid errors when remapping the same address in two
different drivers, because clock and reset of StarFive JH7110 share a common
register address region. For similar implementation, refer to file [1] and [2].

[1] arch/riscv/boot/dts/canaan/k210.dtsi

	sysctl: syscon@50440000 {
		compatible = "canaan,k210-sysctl",
			     "syscon", "simple-mfd";
		reg = <0x50440000 0x100>;
		clocks = <&sysclk K210_CLK_APB1>;
		clock-names = "pclk";

		sysclk: clock-controller {
			#clock-cells = <1>;
			compatible = "canaan,k210-clk";
			clocks = <&in0>;
		};

		sysrst: reset-controller {
			compatible = "canaan,k210-rst";
			#reset-cells = <1>;
		};

		reboot: syscon-reboot {
			compatible = "syscon-reboot";
			regmap = <&sysctl>;
			offset = <48>;
			mask = <1>;
			value = <1>;
		};
	};

[2] drivers/reset/reset-k210.c

> 
> > +
> > +  "#reset-cells":
> > +    const: 1
> > +
> > +  starfive,assert-offset:
> > +    description: Offset of the first ASSERT register
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +  starfive,status-offset:
> > +    description: Offset of the first STATUS register
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> These can't be implied from the compatible string?

These two properties are the key differences among different reset controllers.
There are five memory regions for clock and reset in StarFive JH7110 SoC. They
are "syscrg", "aoncrg", "stgcrg", "ispcrg" and "voutcrg". Each memory region
has different reset ASSERT/STATUS register offset and different number of reset
signals. After storing them in dt, the reset driver can register all reset
controllers with the same compatible string. All we expect is that all reset
controllers in a single SoC use the same compatible string for matching and the
reset driver can be applied to all StarFive SoCs using different compatible strings.
Just like

arch/riscv/boot/dts/starfive/jh7100.dtsi:

	rstgen: reset-controller@11840000 {
		compatible = "starfive,jh7100-reset";
		reg = <0x0 0x11840000 0x0 0x10000>;
		#reset-cells = <1>;
		starfive,assert-offset = <0x0>;
		starfive,status-offset= <0x10>;
		starfive,nr-resets = <JH7100_RSTN_END>;
	};

arch/riscv/boot/dts/starfive/jh7110.dtsi:

	syscrg: syscrg@13020000 {
		compatible = "syscon", "simple-mfd";
		reg = <0x0 0x13020000 0x0 0x10000>;

		syscrg_clk: clock-controller@13020000 {
			compatible = "starfive,jh7110-clkgen-sys";
			...
		};

		syscrg_rst: reset-controller@13020000 {
			compatible = "starfive,jh7110-reset";
			#reset-cells = <1>;
			starfive,assert-offset = <0x2F8>;
			starfive,status-offset= <0x308>;
			starfive,nr-resets = <JH7110_SYSRST_END>;
		};
	};

	aoncrg: aoncrg@17000000 {
		compatible = "syscon", "simple-mfd";
		reg = <0x0 0x17000000 0x0 0x10000>;

		aoncrg_clk: clock-controller@17000000 {
			compatible = "starfive,jh7110-clkgen-aon";
			...
		};

		aoncrg_rst: reset-controller@17000000 {
			compatible = "starfive,jh7110-reset";
			#reset-cells = <1>;
			starfive,assert-offset = <0x38>;
			starfive,status-offset= <0x3C>;
			starfive,nr-resets = <JH7110_AONRST_END>;
		};
	};

	stgcrg: stgcrg@10230000 {	//Not submmited yet
		compatible = "syscon", "simple-mfd";
		reg = <0x0 0x10230000 0x0 0x10000>;

		stgcrg_clk: clock-controller@10230000 {
			compatible = "starfive,jh7110-clkgen-stg";
			...
		};

		stgcrg_rst: reset-controller@10230000 {
			compatible = "starfive,jh7110-reset";
			#reset-cells = <1>;
			starfive,assert-offset = <0x74>;
			starfive,status-offset= <0x78>;
			starfive,nr-resets = <JH7110_STGRST_END>;
		};
	};
	...

> 
> > +
> > +  starfive,nr-resets:
> > +    description: Number of reset signals
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> Why do you need this? Most bindings don't. If just to validate 'resets' 
> args, then don't.

Can be removed. Instead, the reset driver should includes some related
binding headers or defines some macros for pointing out the number of
reset signals of each reset controller.

Best regards,
Hal

> 
> 
> > +
> > +required:
> > +  - compatible
> > +  - "#reset-cells"
> > +  - starfive,assert-offset
> > +  - starfive,status-offset
> > +  - starfive,nr-resets
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/reset/starfive-jh7110.h>
> > +
> > +    syscrg_rst: reset-controller@13020000 {
> > +        compatible = "starfive,jh7110-reset";
> > +        #reset-cells = <1>;
> > +        starfive,assert-offset = <0x2F8>;
> > +        starfive,status-offset= <0x308>;
> > +        starfive,nr-resets = <JH7110_SYSRST_END>;
> > +    };
> > +
> > +...
> > -- 
> > 2.17.1
> > 
> > 
>