Re: [PATCH v3 1/8] clk: sunxi: Add Allwinner A20/A31 GMAC clock unit

[Maxime Ripard]

Hi,

On Mon, Feb 03, 2014 at 11:32:19AM +0800, Chen-Yu Tsai wrote:
> The Allwinner A20/A31 clock module controls the transmit clock source
> and interface type of the GMAC ethernet controller. Model this as
> a single clock for GMAC drivers to use.
> 
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> ---
>  Documentation/devicetree/bindings/clock/sunxi.txt | 26 +++++++
>  drivers/clk/sunxi/clk-sunxi.c                     | 83 +++++++++++++++++++++++
>  2 files changed, 109 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> index 0cf679b..f43b4c0 100644
> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> @@ -37,6 +37,7 @@ Required properties:
>  	"allwinner,sun6i-a31-apb2-gates-clk" - for the APB2 gates on A31
>  	"allwinner,sun4i-mod0-clk" - for the module 0 family of clocks
>  	"allwinner,sun7i-a20-out-clk" - for the external output clocks
> +	"allwinner,sun7i-a20-gmac-clk" - for the GMAC clock module on A20/A31
>  
>  Required properties for all clocks:
>  - reg : shall be the control register address for the clock.
> @@ -50,6 +51,9 @@ Required properties for all clocks:
>  	If the clock module only has one output, the name shall be the
>  	module name.
>  
> +For "allwinner,sun7i-a20-gmac-clk", the parent clocks shall be fixed rate
> +dummy clocks at 25 MHz and 125 MHz, respectively. See example.
> +
>  Clock consumers should specify the desired clocks they use with a
>  "clocks" phandle cell. Consumers that are using a gated clock should
>  provide an additional ID in their clock property. This ID is the
> @@ -96,3 +100,25 @@ mmc0_clk: clk@01c20088 {
>  	clocks = <&osc24M>, <&pll6 1>, <&pll5 1>;
>  	clock-output-names = "mmc0";
>  };
> +
> +mii_phy_tx_clk: clk@2 {
> +	#clock-cells = <0>;
> +	compatible = "fixed-clock";
> +	clock-frequency = <25000000>;
> +	clock-output-names = "mii_phy_tx";
> +};
> +
> +gmac_int_tx_clk: clk@3 {
> +	#clock-cells = <0>;
> +	compatible = "fixed-clock";
> +	clock-frequency = <125000000>;
> +	clock-output-names = "gmac_int_tx";
> +};
> +
> +gmac_clk: clk@01c20164 {
> +	#clock-cells = <0>;
> +	compatible = "allwinner,sun7i-a20-gmac-clk";
> +	reg = <0x01c20164 0x4>;
> +	clocks = <&mii_phy_tx_clk>, <&gmac_int_tx_clk>;

You should also document in which order you expect the parents to
be. Or it will probably be easier to just use clock-names here.

> +	clock-output-names = "gmac";
> +};
> diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
> index 736fb60..0b361d2 100644
> --- a/drivers/clk/sunxi/clk-sunxi.c
> +++ b/drivers/clk/sunxi/clk-sunxi.c
> @@ -379,6 +379,89 @@ static void sun7i_a20_get_out_factors(u32 *freq, u32 parent_rate,
>  
>  
>  /**
> + * sun7i_a20_gmac_clk_setup - Setup function for A20/A31 GMAC clock module
> + *
> + * This clock looks something like this
> + *                               ________________________
> + *  MII TX clock from PHY >-----|___________    _________|----> to GMAC core
> + *  GMAC Int. RGMII TX clk >----|___________\__/__gate---|----> to PHY
> + *  Ext. 125MHz RGMII TX clk >--|__divider__/            |
> + *                              |________________________|
> + *
> + * The external 125 MHz reference is optional, i.e. GMAC can use its
> + * internal TX clock just fine. The A31 GMAC clock module does not have
> + * the divider controls for the external reference.
> + *
> + * To keep it simple, let the GMAC use either the MII TX clock for MII mode,
> + * and its internal TX clock for GMII and RGMII modes. The GMAC driver should
> + * select the appropriate source and gate/ungate the output to the PHY.
> + *
> + * Only the GMAC should use this clock. Altering the clock so that it doesn't
> + * match the GMAC's operation parameters will result in the GMAC not being
> + * able to send traffic out. The GMAC driver should set the clock rate and
> + * enable/disable this clock to configure the required state. The clock
> + * driver then responds by auto-reparenting the clock.
> + */
> +
> +#define SUN7I_A20_GMAC_GPIT	2
> +#define SUN7I_A20_GMAC_MASK	0x3
> +#define SUN7I_A20_GMAC_MAX_PARENTS	2
> +
> +static void __init sun7i_a20_gmac_clk_setup(struct device_node *node)
> +{
> +	struct clk *clk;
> +	struct clk_mux *mux;
> +	struct clk_gate *gate;
> +	const char *clk_name = node->name;
> +	const char *parents[SUN7I_A20_GMAC_MAX_PARENTS];
> +	void *reg;
> +	int i = 0;
> +
> +	/* allocate mux and gate clock structs */
> +	mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
> +	if (!mux)
> +		return;

Newline.

> +	gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
> +	if (!gate) {
> +		kfree(mux);
> +		return;
> +	}
> +
> +	reg = of_iomap(node, 0);

You should check for the return code here.

> +	of_property_read_string(node, "clock-output-names", &clk_name);

And here too, since you made the clock-output-names property mandatory

> +	while (i < SUN7I_A20_GMAC_MAX_PARENTS &&
> +			(parents[i] = of_clk_get_parent_name(node, i)) != NULL)

You should check for an error here too, but if you switch to using
clock-names, that will probably be refactored anyway.

> +		i++;
> +
> +	/* set up gate and fixed rate properties */
> +	gate->reg = reg;
> +	gate->bit_idx = SUN7I_A20_GMAC_GPIT;
> +	gate->lock = &clk_lock;
> +	mux->reg = reg;
> +	mux->mask = SUN7I_A20_GMAC_MASK;
> +	mux->flags = CLK_MUX_INDEX_BIT;
> +	mux->lock = &clk_lock;
> +
> +	clk = clk_register_composite(NULL, clk_name,
> +			parents, i,
> +			&mux->hw, &clk_mux_ops,
> +			NULL, NULL,
> +			&gate->hw, &clk_gate_ops,
> +			0);
> +
> +	if (!IS_ERR(clk)) {
> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +		clk_register_clkdev(clk, clk_name, NULL);
> +	}
> +}
> +CLK_OF_DECLARE(sun7i_a20_gmac, "allwinner,sun7i-a20-gmac-clk",
> +		sun7i_a20_gmac_clk_setup);
> +
> +
> +
> +/**
>   * sunxi_factors_clk_setup() - Setup function for factor clocks
>   */
>  
> -- 
> 1.9.rc1
> 

It looks fine otherwise.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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