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

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

Il 15/01/21 14:02, Vinod Koul ha scritto:
> On 13-01-21, 23:39, AngeloGioacchino Del Regno wrote:
>> 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.
> 
> Yeah I agree we could reuse, I can redo this. I was thinking of making
> this bit as one of the values in register and use that but that does not
> look good as this is not a register offset, so only option is to have a
> new type of PLL for this and use that as here..
> 

Just an idea:

static int __alpha_pll_trion_set_rate(struct clk_hw *hw,
                                       u32 upd_regbit, u32 latch_regbit,
                                       unsigned long rate,
                                       unsigned long prate)

static int alpha_pll_trion_set_rate( args here )
{
	return __alpha_pll_trion_set_rate(hw, PLL_UPDATE,
					 ALPHA_PLL_ACK_LATCH,
					 rate, prate);
}

static int alpha_pll_lucid_5lpe_set_rate( args )
{
	return __alpha_pll_trion_set_rate(hw, LUCID_5LPE_PLL_UPDATE,
					  LUCID_5LPE_PLL_ACK_LATCH,
					  rate, prate);
}

Perhaps, that would be good.

--Angelo