linux-kernel - Re: [PATCH v4 07/13] clk: microchip: mpfs: add MSS pll's set & round rate

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Date:   Thu, 8 Sep 2022 06:46:06 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <Conor.Dooley@...rochip.com>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <palmer@...belt.com>,
        <Daire.McNamara@...rochip.com>
CC:     <paul.walmsley@...ive.com>, <aou@...s.berkeley.edu>,
        <linux-clk@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v4 07/13] clk: microchip: mpfs: add MSS pll's set & round
 rate

On 30.08.2022 15:52, Conor Dooley wrote:
> The MSS pll is not a fixed frequency clock, so add set() & round_rate()
> support.
> Control is limited to a 7 bit output divider as other devices on the
> FPGA occupy the other three outputs of the PLL & prevent changing
> the multiplier.
> 
> Reviewed-by: Daire McNamara <daire.mcnamara@...rochip.com>
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>

Reviewed-by: Claudiu Beznea <claudiu.beznea@...rochip.com>


> ---
>  drivers/clk/microchip/clk-mpfs.c | 54 ++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
> 
> diff --git a/drivers/clk/microchip/clk-mpfs.c b/drivers/clk/microchip/clk-mpfs.c
> index 43cc9583cd14..008b76d81485 100644
> --- a/drivers/clk/microchip/clk-mpfs.c
> +++ b/drivers/clk/microchip/clk-mpfs.c
> @@ -131,8 +131,62 @@ static unsigned long mpfs_clk_msspll_recalc_rate(struct clk_hw *hw, unsigned lon
>  	return prate * mult / (ref_div * MSSPLL_FIXED_DIV * postdiv);
>  }
>  
> +static long mpfs_clk_msspll_round_rate(struct clk_hw *hw, unsigned long rate, unsigned long *prate)
> +{
> +	struct mpfs_msspll_hw_clock *msspll_hw = to_mpfs_msspll_clk(hw);
> +	void __iomem *mult_addr = msspll_hw->base + msspll_hw->reg_offset;
> +	void __iomem *ref_div_addr = msspll_hw->base + REG_MSSPLL_REF_CR;
> +	u32 mult, ref_div;
> +	unsigned long rate_before_ctrl;
> +
> +	mult = readl_relaxed(mult_addr) >> MSSPLL_FBDIV_SHIFT;
> +	mult &= clk_div_mask(MSSPLL_FBDIV_WIDTH);
> +	ref_div = readl_relaxed(ref_div_addr) >> MSSPLL_REFDIV_SHIFT;
> +	ref_div &= clk_div_mask(MSSPLL_REFDIV_WIDTH);
> +
> +	rate_before_ctrl = rate * (ref_div * MSSPLL_FIXED_DIV) / mult;
> +
> +	return divider_round_rate(hw, rate_before_ctrl, prate, NULL, MSSPLL_POSTDIV_WIDTH,
> +				  msspll_hw->flags);
> +}
> +
> +static int mpfs_clk_msspll_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long prate)
> +{
> +	struct mpfs_msspll_hw_clock *msspll_hw = to_mpfs_msspll_clk(hw);
> +	void __iomem *mult_addr = msspll_hw->base + msspll_hw->reg_offset;
> +	void __iomem *ref_div_addr = msspll_hw->base + REG_MSSPLL_REF_CR;
> +	void __iomem *postdiv_addr = msspll_hw->base + REG_MSSPLL_POSTDIV_CR;
> +	u32 mult, ref_div, postdiv;
> +	int divider_setting;
> +	unsigned long rate_before_ctrl, flags;
> +
> +	mult = readl_relaxed(mult_addr) >> MSSPLL_FBDIV_SHIFT;
> +	mult &= clk_div_mask(MSSPLL_FBDIV_WIDTH);
> +	ref_div = readl_relaxed(ref_div_addr) >> MSSPLL_REFDIV_SHIFT;
> +	ref_div &= clk_div_mask(MSSPLL_REFDIV_WIDTH);
> +
> +	rate_before_ctrl = rate * (ref_div * MSSPLL_FIXED_DIV) / mult;
> +	divider_setting = divider_get_val(rate_before_ctrl, prate, NULL, MSSPLL_POSTDIV_WIDTH,
> +					  msspll_hw->flags);
> +
> +	if (divider_setting < 0)
> +		return divider_setting;
> +
> +	spin_lock_irqsave(&mpfs_clk_lock, flags);
> +
> +	postdiv = readl_relaxed(postdiv_addr);
> +	postdiv &= ~(clk_div_mask(MSSPLL_POSTDIV_WIDTH) << MSSPLL_POSTDIV_SHIFT);
> +	writel_relaxed(postdiv, postdiv_addr);
> +
> +	spin_unlock_irqrestore(&mpfs_clk_lock, flags);
> +
> +	return 0;
> +}
> +
>  static const struct clk_ops mpfs_clk_msspll_ops = {
>  	.recalc_rate = mpfs_clk_msspll_recalc_rate,
> +	.round_rate = mpfs_clk_msspll_round_rate,
> +	.set_rate = mpfs_clk_msspll_set_rate,
>  };
>  
>  #define CLK_PLL(_id, _name, _parent, _shift, _width, _flags, _offset) {			\