Re: [PATCH v4 2/7] clk: qcom: Add generic clkref_en support

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 5/28/26 4:29 AM, Qiang Yu wrote:
> Before XO refclk is distributed to PCIe/USB/eDP PHYs, it passes through
> a QREF block. QREF is powered by dedicated LDO rails, and the clkref_en
> register controls whether refclk is gated through to the PHY side.
> 
> These clkref controls are different from typical GCC branch clocks:
> - only a single enable bit is present, without branch-style config bits
> - regulators must be voted before enable and unvoted after disable
> 
> Model this as a dedicated clk_ref clock type with custom clk_ops instead
> of reusing struct clk_branch semantics.
> 
> Also provide a common registration/probe API so the same clkref model
> can be reused regardless of where clkref_en registers are placed, e.g.
> TCSR on glymur and TLMM on SM8750.
> 
> Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
> ---

[...]

> +static int qcom_clk_ref_enable(struct clk_hw *hw)
> +{
> +	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
> +	int ret;
> +
> +	ret = regmap_update_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK,
> +				 QCOM_CLK_REF_EN_MASK);

regmap_set_bits()

> +	if (ret)
> +		return ret;
> +
> +	udelay(10);
> +
> +	return 0;
> +}
> +
> +static void qcom_clk_ref_disable(struct clk_hw *hw)
> +{
> +	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
> +
> +	regmap_update_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK, 0);

regmap_clear_bits()

[...]

> +static int qcom_clk_ref_register(struct device *dev, struct regmap *regmap,
> +				 struct qcom_clk_ref *clk_refs,
> +				 const struct qcom_clk_ref_desc *descs,
> +				 size_t num_clk_refs)
> +{
> +	const struct qcom_clk_ref_desc *desc;
> +	struct qcom_clk_ref *clk_ref;
> +	size_t clk_idx;
> +	unsigned int i;
> +	int ret;
> +
> +	for (clk_idx = 0; clk_idx < num_clk_refs; clk_idx++) {
> +		clk_ref = &clk_refs[clk_idx];
> +		desc = &descs[clk_idx];
> +
> +		if (!desc->name)
> +			continue;

// this allows "holes" in dt-bindings for $reasons
if (!desc)
	continue;

// this makes sure the programmer did not omit something important
// while not taking the entire system down
if (WARN_ON(!desc->name)
	continue;


Konrad