[PATCH v5 1/2] clk: starfive: jh7110-sys: Add notifier for PLL0 clock

[Emil Renner Berthing]

Xingyu Wu wrote:
> Add notifier function for PLL0 clock. In the function, the cpu_root clock
> should be operated by saving its current parent and setting a new safe
> parent (osc clock) before setting the PLL0 clock rate. After setting PLL0
> rate, it should be switched back to the original parent clock.
>
> Fixes: e2c510d6d630 ("riscv: dts: starfive: Add cpu scaling for JH7110 SoC")
> Signed-off-by: Xingyu Wu <xingyu.wu at starfivetech.com>

This looks much better, thanks!

Reviewed-by: Emil Renner Berthing <emil.renner.berthing at canonical.com>

> ---
>  .../clk/starfive/clk-starfive-jh7110-sys.c    | 31 ++++++++++++++++++-
>  drivers/clk/starfive/clk-starfive-jh71x0.h    |  2 ++
>  2 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/starfive/clk-starfive-jh7110-sys.c b/drivers/clk/starfive/clk-starfive-jh7110-sys.c
> index 8f5e5abfa178..dafa3ae71751 100644
> --- a/drivers/clk/starfive/clk-starfive-jh7110-sys.c
> +++ b/drivers/clk/starfive/clk-starfive-jh7110-sys.c
> @@ -385,6 +385,32 @@ int jh7110_reset_controller_register(struct jh71x0_clk_priv *priv,
>  }
>  EXPORT_SYMBOL_GPL(jh7110_reset_controller_register);
>
> +/*
> + * This clock notifier is called when the rate of PLL0 clock is to be changed.
> + * The cpu_root clock should save the curent parent clock and swicth its parent
> + * clock to osc before PLL0 rate will be changed. Then swicth its parent clock
> + * back after the PLL0 rate is completed.
> + */
> +static int jh7110_pll0_clk_notifier_cb(struct notifier_block *nb,
> +				       unsigned long action, void *data)
> +{
> +	struct jh71x0_clk_priv *priv = container_of(nb, struct jh71x0_clk_priv, pll_clk_nb);
> +	struct clk *cpu_root = priv->reg[JH7110_SYSCLK_CPU_ROOT].hw.clk;
> +	int ret = 0;
> +
> +	if (action == PRE_RATE_CHANGE) {
> +		struct clk *osc = clk_get(priv->dev, "osc");
> +
> +		priv->original_clk = clk_get_parent(cpu_root);
> +		ret = clk_set_parent(cpu_root, osc);
> +		clk_put(osc);
> +	} else if (action == POST_RATE_CHANGE) {
> +		ret = clk_set_parent(cpu_root, priv->original_clk);
> +	}
> +
> +	return notifier_from_errno(ret);
> +}
> +
>  static int __init jh7110_syscrg_probe(struct platform_device *pdev)
>  {
>  	struct jh71x0_clk_priv *priv;
> @@ -413,7 +439,10 @@ static int __init jh7110_syscrg_probe(struct platform_device *pdev)
>  		if (IS_ERR(priv->pll[0]))
>  			return PTR_ERR(priv->pll[0]);
>  	} else {
> -		clk_put(pllclk);
> +		priv->pll_clk_nb.notifier_call = jh7110_pll0_clk_notifier_cb;
> +		ret = clk_notifier_register(pllclk, &priv->pll_clk_nb);
> +		if (ret)
> +			return ret;
>  		priv->pll[0] = NULL;
>  	}
>
> diff --git a/drivers/clk/starfive/clk-starfive-jh71x0.h b/drivers/clk/starfive/clk-starfive-jh71x0.h
> index 23e052fc1549..e3f441393e48 100644
> --- a/drivers/clk/starfive/clk-starfive-jh71x0.h
> +++ b/drivers/clk/starfive/clk-starfive-jh71x0.h
> @@ -114,6 +114,8 @@ struct jh71x0_clk_priv {
>  	spinlock_t rmw_lock;
>  	struct device *dev;
>  	void __iomem *base;
> +	struct clk *original_clk;
> +	struct notifier_block pll_clk_nb;
>  	struct clk_hw *pll[3];
>  	struct jh71x0_clk reg[];
>  };
> --
> 2.25.1
>
>
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