Subject: [PATCH 06/10] clk: sunxi: mod0 support

From: [email-masked] (Maxime Ripard)
Date: Mon, 30 Sep 2013 19:35:08 +0200

Hi Emilio,

Overall, it looks fine, I just have a small question.

On Sun, Sep 29, 2013 at 12:49:35AM -0300, Emilio L?pez wrote:
> This commit implements support for the "module 0" type of clocks, as
> used by MMC, IR, NAND, SATA and other components.
> 
> Signed-off-by: Emilio L?pez <[email-masked]>
> ---
>  Documentation/devicetree/bindings/clock/sunxi.txt |  1 +
>  drivers/clk/sunxi/clk-sunxi.c                     | 57 +++++++++++++++++++++++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> index 773f3ae..ff3f61c 100644
> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> @@ -35,6 +35,7 @@ Required properties:
>  	"allwinner,sun7i-a20-apb1-gates-clk" - for the APB1 gates on A20
>  	"allwinner,sun6i-a31-apb2-div-clk" - for the APB2 gates on A31
>  	"allwinner,sun6i-a31-apb2-gates-clk" - for the APB2 gates on A31
> +	"allwinner,sun4i-mod0-clk" - for the module 0 family of clocks
>  
>  Required properties for all clocks:
>  - reg : shall be the control register address for the clock.
> diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
> index b1210f3..163a3d8 100644
> --- a/drivers/clk/sunxi/clk-sunxi.c
> +++ b/drivers/clk/sunxi/clk-sunxi.c
> @@ -287,6 +287,47 @@ static void sun4i_get_apb1_factors(u32 *freq, u32 parent_rate,
>  
>  
>  /**
> + * sun4i_get_mod0_factors() - calculates m, n factors for MOD0-style clocks
> + * MMC rate is calculated as follows
> + * rate = (parent_rate >> p) / (m + 1);
> + */
> +
> +static void sun4i_get_mod0_factors(u32 *freq, u32 parent_rate,
> +				   u8 *n, u8 *k, u8 *m, u8 *p)
> +{
> +	u8 div, calcm, calcp;
> +
> +	/* These clocks can only divide, so we will never be able to achieve
> +	 * frequencies higher than the parent frequency */
> +	if (*freq > parent_rate)
> +		*freq = parent_rate;
> +
> +	div = parent_rate / *freq;
> +
> +	if (div < 16)
> +		calcp = 0;
> +	else if (div / 2 < 16)
> +		calcp = 1;
> +	else if (div / 4 < 16)
> +		calcp = 2;
> +	else
> +		calcp = 3;
> +
> +	calcm = DIV_ROUND_UP(div, 1 << calcp);
> +
> +	*freq = (parent_rate >> calcp) / calcm;
> +
> +	/* we were called to round the frequency, we can now return */
> +	if (n == NULL)
> +		return;
> +
> +	*m = calcm - 1;
> +	*p = calcp;
> +}
> +
> +
> +
> +/**
>   * sunxi_factors_clk_setup() - Setup function for factor clocks
>   */
>  
> @@ -333,6 +374,14 @@ static struct clk_factors_config sun4i_apb1_config = {
>  	.pwidth = 2,
>  };
>  
> +/* user manual says "n" but it's really "p" */
> +static struct clk_factors_config sun4i_mod0_config = {
> +	.mshift = 0,
> +	.mwidth = 4,
> +	.pshift = 16,
> +	.pwidth = 2,
> +};
> +
>  static const struct factors_data sun4i_pll1_data __initconst = {
>  	.enable = 31,
>  	.table = &sun4i_pll1_config,
> @@ -356,6 +405,13 @@ static const struct factors_data sun4i_apb1_data __initconst = {
>  	.getter = sun4i_get_apb1_factors,
>  };
>  
> +static const struct factors_data sun4i_mod0_data __initconst = {
> +	.enable = 31,
> +	.mux = 24,
> +	.table = &sun4i_mod0_config,
> +	.getter = sun4i_get_mod0_factors,
> +};

How are the parents handled here for the mux part? Do you expect the
different parents in a precise order in the device tree, so that you
have a direct mapping to the value to put in the muxing registers, or do
you have a smarter way to do it?

Thanks,
Maxime

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