Re: [PATCH v7 1/2] phy: Add new Exynos5 USB 3.0 PHY driver

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

On 28/04/14 08:17, Vivek Gautam wrote:
> Add a new driver for the USB 3.0 PHY on Exynos5 series of SoCs.
> The new driver uses the generic PHY framework and will interact
> with DWC3 controller present on Exynos5 series of SoCs.
> Thereby, removing old phy-samsung-usb3 driver and related code
> used untill now which was based on usb/phy framework.
> 
> Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
> ---
> 
> Changes from v6:
>  - Addressed review comments:
>    -- Sorted config entries in Kconfig and Makefile
>    -- Made #define to_usbdrd_phy(inst) to a static inline routine.
>    -- Restructured exynos5_rate_to_clk() as suggested.
>    -- Amended 'val' field for regmap_update_bits() in the routine
>       exynos5_usbdrd_phy_isol().
>    -- Removed sentinel entry from exynos5_usbdrd_phy_cfg[] struct.
>    -- Removed check for 'match' entry in probe().
> 
>  .../devicetree/bindings/phy/samsung-phy.txt        |   40 ++
>  drivers/phy/Kconfig                                |   11 +
>  drivers/phy/Makefile                               |    1 +
>  drivers/phy/phy-exynos5-usbdrd.c                   |  627 ++++++++++++++++++++
>  4 files changed, 679 insertions(+)
>  create mode 100644 drivers/phy/phy-exynos5-usbdrd.c
> 
> diff --git a/Documentation/devicetree/bindings/phy/samsung-phy.txt b/Documentation/devicetree/bindings/phy/samsung-phy.txt
> index b422e38..51efe4c 100644
> --- a/Documentation/devicetree/bindings/phy/samsung-phy.txt
> +++ b/Documentation/devicetree/bindings/phy/samsung-phy.txt
> @@ -114,3 +114,43 @@ Example:
>  		compatible = "samsung,exynos-sataphy-i2c";
>  		reg = <0x38>;
>  	};
> +
> +Samsung Exynos5 SoC series USB DRD PHY controller
> +--------------------------------------------------
> +
> +Required properties:
> +- compatible : Should be set to one of the following supported values:
> +	- "samsung,exynos5250-usbdrd-phy" - for exynos5250 SoC,
> +	- "samsung,exynos5420-usbdrd-phy" - for exynos5420 SoC.
> +- reg : Register offset and length of USB DRD PHY register set;
> +- clocks: Clock IDs array as required by the controller
> +- clock-names: names of clocks correseponding to IDs in the clock property;
> +	       Required clocks:
> +	- phy: main PHY clock (same as USB DRD controller i.e. DWC3 IP clock),
> +	       used for register access.
> +	- ref: PHY's reference clock (usually crystal clock), used for
> +	       PHY operations, associated by phy name. It is used to
> +	       determine bit values for clock settings register.
> +	       For Exynos5420 this is given as 'sclk_usbphy30' in CMU.
> +- samsung,pmu-syscon: phandle for PMU system controller interface, used to
> +		      control pmu registers for power isolation.
> +- samsung,pmu-offset: phy power control register offset to pmu-system-controller
> +		      base.

It doesn't seem right to have register offset encoded in the device tree
like this. I think it'd be more appropriate to associate such an offset
with the compatible string's value in the driver.

Also it might be sensible to create a new header file in include/linux/mfd/
syscon/ for Exynos5 SoCs and put any required PMU offset definitions there. 
Instead having them scattered and possibly duplicated in various drivers.

> +- #phy-cells : from the generic PHY bindings, must be 1;
> +
> +For "samsung,exynos5250-usbdrd-phy" and "samsung,exynos5420-usbdrd-phy"
> +compatible PHYs, the second cell in the PHY specifier identifies the
> +PHY id, which is interpreted as follows:
> +  0 - UTMI+ type phy,
> +  1 - PIPE3 type phy,
> +
> +Example:
> +	usb3_phy: usbphy@12100000 {
> +		compatible = "samsung,exynos5250-usbdrd-phy";
> +		reg = <0x12100000 0x100>;
> +		clocks = <&clock 286>, <&clock 1>;
> +		clock-names = "phy", "ref";
> +		samsung,pmu-syscon = <&pmu_system_controller>;
> +		samsung,pmu-offset = <0x704>;
> +		#phy-cells = <1>;
> +	};
[...]
> +struct usbdrd_phy_config {

Isn't name of this data structure too generic ? 
Perhaps rename it to exynos_usbdrd_phy_config ?

> +	u32 id;
> +	void (*phy_isol)(struct phy_usb_instance *inst, u32 on);
> +	void (*phy_init)(struct exynos5_usbdrd_phy *phy_drd);
> +	unsigned int (*set_refclk)(struct phy_usb_instance *inst);
> +};
> +
> +struct exynos5_usbdrd_phy_drvdata {
> +	const struct usbdrd_phy_config *phy_cfg;
> +};
> +
[...]
> +const struct exynos5_usbdrd_phy_drvdata exynos5420_usbdrd_phy = {
> +	.phy_cfg		= exynos5_usbdrd_phy_cfg,
> +};
> +
> +const struct exynos5_usbdrd_phy_drvdata exynos5250_usbdrd_phy = {
> +	.phy_cfg		= exynos5_usbdrd_phy_cfg,
> +};
> +
> +static const struct of_device_id exynos5_usbdrd_phy_of_match[] = {
> +	{
> +		.compatible = "samsung,exynos5250-usbdrd-phy",
> +		.data = &exynos5250_usbdrd_phy
> +	}, {
> +		.compatible = "samsung,exynos5420-usbdrd-phy",
> +		.data = &exynos5420_usbdrd_phy
> +	},
> +	{ },
> +};
> +
> +static int exynos5_usbdrd_phy_probe(struct platform_device *pdev)
> +{
[...]
> +	reg_pmu = syscon_regmap_lookup_by_phandle(dev->of_node,
> +						   "samsung,pmu-syscon");
> +	if (IS_ERR(reg_pmu)) {
> +		dev_err(dev, "Failed to map PMU register (via syscon)\n");

nit: Maybe change it to: "Failed to lookup PMU regmap\n" ?

> +		return PTR_ERR(reg_pmu);
> +	}
> +
> +	ret = of_property_read_u32(node, "samsung,pmu-offset", &pmu_offset);
> +	if (ret) {
> +		dev_err(dev, "Missing pmu-offset for phy isolation\n");
> +		return ret;
> +	}

Otherwise the patch looks good.

--
Thanks,
Sylwester