linux-kernel - Re: [PATCHv2] clk:aspeed:Fix AST2600 hpll calculate formula

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Date:   Mon, 13 Sep 2021 05:26:27 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <ryan_chen@...eedtech.com>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <joel@....id.au>, <andrew@...id.au>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] clk:aspeed:Fix AST2600 hpll calculate formula

On 08.09.2021 12:18, Ryan Chen wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> AST2600 HPLL calculate formula [SCU200]
> HPLL Numerator(M): have fixed value depend on SCU strap.
> M = SCU500[10] ? 0x5F : SCU500[8] ? 0xBF : SCU200[12:0]
> 
> if SCU500[10] = 1, M=0x5F.
> else if SCU500[10]=0 & SCU500[8]=1, M=0xBF.
> others (SCU510[10]=0 and SCU510[8]=0)
> depend on SCU200[12:0] (default 0x8F) register setting.
> 
> HPLL Denumerator (N) =  SCU200[18:13] (default 0x2)
> HPLL Divider (P)         =      SCU200[22:19] (default 0x0)
> 
> Fixes: d3d04f6c330a ("clk: Add support for AST2600 SoC")
> Signed-off-by: Ryan Chen <ryan_chen@...eedtech.com>
> ---
>  drivers/clk/clk-ast2600.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
> index 085d0a18b2b6..5d8c46bcf237 100644
> --- a/drivers/clk/clk-ast2600.c
> +++ b/drivers/clk/clk-ast2600.c
> @@ -169,6 +169,33 @@ static const struct clk_div_table ast2600_div_table[] = {
>  };
> 
>  /* For hpll/dpll/epll/mpll */
> +static struct clk_hw *ast2600_calc_hpll(const char *name, u32 val)
> +{
> +       unsigned int mult, div;
> +       u32 hwstrap = readl(scu_g6_base + ASPEED_G6_STRAP1);
> +
> +       if (val & BIT(24)) {
> +               /* Pass through mode */
> +               mult = div = 1;
> +       } else {
> +               /* F = 25Mhz * [(M + 2) / (n + 1)] / (p + 1) */
> +               u32 m = val  & 0x1fff;
> +               u32 n = (val >> 13) & 0x3f;
> +               u32 p = (val >> 19) & 0xf;
> +
> +               if (hwstrap & BIT(10))
> +                       m = 0x5F;
> +               else {
> +                       if (hwstrap & BIT(8))

You may write it directly:
		  else if (hwstrap & BIT(8))

> +                               m = 0xBF;
> +               }
> +               mult = (m + 1) / (n + 1);
> +               div = (p + 1);
> +       }
> +       return clk_hw_register_fixed_factor(NULL, name, "clkin", 0,
> +                       mult, div);
> +};
> +
>  static struct clk_hw *ast2600_calc_pll(const char *name, u32 val)
>  {
>         unsigned int mult, div;
> @@ -716,7 +743,7 @@ static void __init aspeed_g6_cc(struct regmap *map)
>          * and we assume that it is enabled
>          */
>         regmap_read(map, ASPEED_HPLL_PARAM, &val);
> -       aspeed_g6_clk_data->hws[ASPEED_CLK_HPLL] = ast2600_calc_pll("hpll", val);
> +       aspeed_g6_clk_data->hws[ASPEED_CLK_HPLL] = ast2600_calc_hpll("hpll", val);
> 
>         regmap_read(map, ASPEED_MPLL_PARAM, &val);
>         aspeed_g6_clk_data->hws[ASPEED_CLK_MPLL] = ast2600_calc_pll("mpll", val);
> --
> 2.17.1
>