Re: [PATCH 2/4] clk: qcom: clk-alpha-pll: Add support for Lucid 5LPE PLL

[AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>]

Il 05/01/21 16:46, Vinod Koul ha scritto:
> From: Vivek Aknurwar <viveka@codeaurora.org>
> 
> Lucid 5LPE is a slightly different Lucid PLL with different offsets and
> porgramming sequence so add support for these
> 
> Signed-off-by: Vivek Aknurwar <viveka@codeaurora.org>
> Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>
> [vkoul: rebase and tidy up for upstream]
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>   drivers/clk/qcom/clk-alpha-pll.c | 217 +++++++++++++++++++++++++++++++
>   drivers/clk/qcom/clk-alpha-pll.h |   4 +
>   2 files changed, 221 insertions(+)
> 
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index f7721088494c..843c43649a5a 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -156,6 +156,12 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_regs);
>   /* LUCID PLL specific settings and offsets */
>   #define LUCID_PCAL_DONE		BIT(27)
>   
> +/* LUCID 5LPE PLL specific settings and offsets */
> +#define LUCID_5LPE_PCAL_DONE		BIT(11)
> +#define LUCID_5LPE_ALPHA_PLL_ACK_LATCH	BIT(13)
> +#define LUCID_5LPE_PLL_LATCH_INPUT	BIT(14)
> +#define LUCID_5LPE_ENABLE_VOTE_RUN	BIT(21)
> +
>   #define pll_alpha_width(p)					\
>   		((PLL_ALPHA_VAL_U(p) - PLL_ALPHA_VAL(p) == 4) ?	\
>   				 ALPHA_REG_BITWIDTH : ALPHA_REG_16BIT_WIDTH)
> @@ -1600,3 +1606,214 @@ const struct clk_ops clk_alpha_pll_agera_ops = {
>   	.set_rate = clk_alpha_pll_agera_set_rate,
>   };
>   EXPORT_SYMBOL_GPL(clk_alpha_pll_agera_ops);
> +
> +static int alpha_pll_lucid_5lpe_enable(struct clk_hw *hw)
> +{
> +	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> +	u32 val;
> +	int ret;
> +
> +	ret = regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &val);
> +	if (ret)
> +		return ret;
> +
> +	/* If in FSM mode, just vote for it */
> +	if (val & LUCID_5LPE_ENABLE_VOTE_RUN) {
> +		ret = clk_enable_regmap(hw);
> +		if (ret)
> +			return ret;
> +		return wait_for_pll_enable_lock(pll);
> +	}
> +
> +	/* Check if PLL is already enabled, return if enabled */
> +	ret = trion_pll_is_enabled(pll, pll->clkr.regmap);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_RESET_N, PLL_RESET_N);
> +	if (ret)
> +		return ret;
> +
> +	regmap_write(pll->clkr.regmap, PLL_OPMODE(pll), PLL_RUN);
> +
> +	ret = wait_for_pll_enable_lock(pll);
> +	if (ret)
> +		return ret;
> +
> +	/* Enable the PLL outputs */
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll), PLL_OUT_MASK, PLL_OUT_MASK);
> +	if (ret)
> +		return ret;
> +
> +	/* Enable the global PLL outputs */
> +	return regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_OUTCTRL, PLL_OUTCTRL);
> +}
> +
> +static void alpha_pll_lucid_5lpe_disable(struct clk_hw *hw)
> +{
> +	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> +	u32 val;
> +	int ret;
> +
> +	ret = regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &val);
> +	if (ret)
> +		return;
> +
> +	/* If in FSM mode, just unvote it */
> +	if (val & LUCID_5LPE_ENABLE_VOTE_RUN) {
> +		clk_disable_regmap(hw);
> +		return;
> +	}
> +
> +	/* Disable the global PLL output */
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_OUTCTRL, 0);
> +	if (ret)
> +		return;
> +
> +	/* Disable the PLL outputs */
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll), PLL_OUT_MASK, 0);
> +	if (ret)
> +		return;
> +
> +	/* Place the PLL mode in STANDBY */
> +	regmap_write(pll->clkr.regmap, PLL_OPMODE(pll), PLL_STANDBY);
> +}
> +
> +/*
> + * The Lucid 5LPE PLL requires a power-on self-calibration which happens
> + * when the PLL comes out of reset. Calibrate in case it is not completed.
> + */
> +static int alpha_pll_lucid_5lpe_prepare(struct clk_hw *hw)
> +{
> +	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> +	struct clk_hw *p;
> +	u32 val;
> +	int ret;
> +
> +	/* Return early if calibration is not needed. */
> +	regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
> +	if (val & LUCID_5LPE_PCAL_DONE)
> +		return 0;
> +
> +	p = clk_hw_get_parent(hw);
> +	if (!p)
> +		return -EINVAL;
> +
> +	ret = alpha_pll_lucid_5lpe_enable(hw);
> +	if (ret)
> +		return ret;
> +
> +	alpha_pll_lucid_5lpe_disable(hw);
> +
> +	return 0;
> +}
> +
> +static int alpha_pll_lucid_5lpe_set_rate(struct clk_hw *hw, unsigned long rate,
> +					 unsigned long prate)
> +{
> +	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> +	unsigned long rrate;
> +	u32 val, l;
> +	u64 a;
> +	int ret;
> +
> +	rrate = alpha_pll_round_rate(rate, prate, &l, &a, ALPHA_REG_16BIT_WIDTH);
> +
> +	/*
> +	 * Due to a limited number of bits for fractional rate programming, the
> +	 * rounded up rate could be marginally higher than the requested rate.
> +	 */
> +	ret = alpha_pll_check_rate_margin(hw, rrate, rate);
> +	if (ret)
> +		return ret;
> +
> +	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
> +	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
> +
> +	/* Latch the PLL input */
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
> +				 LUCID_5LPE_PLL_LATCH_INPUT, LUCID_5LPE_PLL_LATCH_INPUT);
> +	if (ret)
> +		return ret;
> +
> +	/* Wait for 2 reference cycles before checking the ACK bit. */
> +	udelay(1);
> +	regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
> +	if (!(val & LUCID_5LPE_ALPHA_PLL_ACK_LATCH)) {
> +		pr_err("Lucid 5LPE PLL latch failed. Output may be unstable!\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Return the latch input to 0 */
> +	ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), LUCID_5LPE_PLL_LATCH_INPUT, 0);
> +	if (ret)
> +		return ret;
> +
> +	if (clk_hw_is_enabled(hw)) {
> +		ret = wait_for_pll_enable_lock(pll);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/* Wait for PLL output to stabilize */
> +	udelay(100);
> +	return 0;
> +}
> +

This one looks exactly like alpha_pll_trion_set_rate() but:
1. You are forcing ALPHA_REG_16BIT_WIDTH for the alpha_pll_round_rate
    call: this is bad, you should actually use pll_alpha_width(pll) here,
    unless you have a very good reason that I didn't understand...
2. The only change between these two functions (trion and
    lucid_5lpe_set_rate) is that PLL_UPDATE becomes
    LUCID_5LPE_PLL_LATCH_INPUT, and that you check for
    LUCID_5LPE_ALPHA_PLL_ACK_LATCH instead of ALPHA_PLL_ACK_LATCH: this
    looks like being 95% code duplication.

The best options here, in my opinion, would be to commonize the function
alpha_pll_trion_set_rate: that will avoid this huge duplication.

> +static int clk_lucid_5lpe_pll_postdiv_set_rate(struct clk_hw *hw, unsigned long rate,
> +					       unsigned long parent_rate)
> +{
> +	struct clk_alpha_pll_postdiv *pll = to_clk_alpha_pll_postdiv(hw);
> +	int i, val = 0, div, ret;
> +	u32 mask;
> +
> +	/*
> +	 * If the PLL is in FSM mode, then treat set_rate callback as a
> +	 * no-operation.
> +	 */
> +	ret = regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val & LUCID_5LPE_ENABLE_VOTE_RUN)
> +		return 0;
> +
> +	div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
> +	for (i = 0; i < pll->num_post_div; i++) {
> +		if (pll->post_div_table[i].div == div) {
> +			val = pll->post_div_table[i].val;
> +			break;
> +		}
> +	}
> +
> +	mask = GENMASK(pll->width + pll->post_div_shift - 1, pll->post_div_shift);
> +	return regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll),
> +				  mask, val << pll->post_div_shift);
> +}
> +
> +const struct clk_ops clk_alpha_pll_lucid_5lpe_ops = {
> +	.prepare = alpha_pll_lucid_5lpe_prepare,
> +	.enable = alpha_pll_lucid_5lpe_enable,
> +	.disable = alpha_pll_lucid_5lpe_disable,
> +	.is_enabled = clk_trion_pll_is_enabled,
> +	.recalc_rate = clk_trion_pll_recalc_rate,
> +	.round_rate = clk_alpha_pll_round_rate,
> +	.set_rate = alpha_pll_lucid_5lpe_set_rate,
> +};
> +EXPORT_SYMBOL(clk_alpha_pll_lucid_5lpe_ops);
> +
> +const struct clk_ops clk_alpha_pll_fixed_lucid_5lpe_ops = {
> +	.enable = alpha_pll_lucid_5lpe_enable,
> +	.disable = alpha_pll_lucid_5lpe_disable,
> +	.is_enabled = clk_trion_pll_is_enabled,
> +	.recalc_rate = clk_trion_pll_recalc_rate,
> +	.round_rate = clk_alpha_pll_round_rate,
> +};
> +EXPORT_SYMBOL(clk_alpha_pll_fixed_lucid_5lpe_ops);
> +
> +const struct clk_ops clk_alpha_pll_postdiv_lucid_5lpe_ops = {
> +	.recalc_rate = clk_alpha_pll_postdiv_fabia_recalc_rate,
> +	.round_rate = clk_alpha_pll_postdiv_fabia_round_rate,
> +	.set_rate = clk_lucid_5lpe_pll_postdiv_set_rate,
> +};
> +EXPORT_SYMBOL(clk_alpha_pll_postdiv_lucid_5lpe_ops);
> diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
> index 0ea30d2f3da1..6943e933be0f 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.h
> +++ b/drivers/clk/qcom/clk-alpha-pll.h
> @@ -144,6 +144,10 @@ extern const struct clk_ops clk_alpha_pll_lucid_ops;
>   extern const struct clk_ops clk_alpha_pll_postdiv_lucid_ops;
>   extern const struct clk_ops clk_alpha_pll_agera_ops;
>   
> +extern const struct clk_ops clk_alpha_pll_lucid_5lpe_ops;
> +extern const struct clk_ops clk_alpha_pll_fixed_lucid_5lpe_ops;
> +extern const struct clk_ops clk_alpha_pll_postdiv_lucid_5lpe_ops;
> +
>   void clk_alpha_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
>   			     const struct alpha_pll_config *config);
>   void clk_fabia_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
>