[PATCH v3 04/12] clk: qcom: ipq-cmn-pll: Register CMN PLL /2 clock

[Luo Jie]

Most CMN PLL output clocks are derived from the 12 GHz PLL output
through a shared, physical /2 stage, ahead of any further per-clock
processing: a gated fixed rate (PCS/ETH0/ETH1/ETH2/EPHY/ETH), a
configurable divider (NSS/PPE/PON), or a rate-select bit (EPHY-RAW).
This /2 stage is present in the CMN PLL block on every SoC supported
by this driver, not just IPQ5210.

Register this /2 stage once as a fixed-factor clock, "cmn_pll_div2",
and store it on struct clk_cmn_pll so the output clock types added by
later patches can parent on it. The two plain fixed-rate outputs,
xo-24mhz and sleep-32khz, are the exception on IPQ5210 SoC: they stay
parented directly on the main PLL clock.

On SoCs other than IPQ5210, every output clock is a plain fixed-rate
clock (CMN_PLL_CLK_FIXED_RATE) whose rate is a hardcoded absolute
value rather than one computed from the parent rate, so this /2 clock
is registered there but currently has no consumers; IPQ5210 is simply
the first SoC in this driver whose output clocks are modeled as
depending on parent_rate, which is what makes the /2 stage significant.

This patch only registers the clock; later patches wire it in as the
effective parent for the output clock types that sit downstream of it.

Signed-off-by: Luo Jie <jie.luo@xxxxxxxxxxxxxxxx>
---
 drivers/clk/qcom/ipq-cmn-pll.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/clk/qcom/ipq-cmn-pll.c b/drivers/clk/qcom/ipq-cmn-pll.c
index 4fdf78f6829e..bcb51a5f559a 100644
--- a/drivers/clk/qcom/ipq-cmn-pll.c
+++ b/drivers/clk/qcom/ipq-cmn-pll.c
@@ -96,10 +96,17 @@ struct cmn_pll_fixed_output_clk {
  * struct clk_cmn_pll - CMN PLL hardware specific data
  * @regmap: hardware regmap.
  * @hw: handle between common and hardware-specific interfaces
+ * @div2_hw: fixed /2 clock derived from the CMN PLL output; present on
+ *           every supported SoC, but only IPQ5210 currently parents
+ *           any output clock on it (every output clock except the
+ *           plain fixed-rate xo/sleep clocks, which stay on the main
+ *           PLL); other SoCs' output clocks use hardcoded rates that
+ *           never depend on a parent
  */
 struct clk_cmn_pll {
 	struct regmap *regmap;
 	struct clk_hw hw;
+	struct clk_hw *div2_hw;
 };
 
 #define CLK_PLL_OUTPUT(_id, _name, _rate) {		\
@@ -362,6 +369,7 @@ static int ipq_cmn_pll_register_clks(struct platform_device *pdev)
 	const struct cmn_pll_fixed_output_clk *p, *fixed_clk;
 	struct clk_hw_onecell_data *hw_data;
 	struct device *dev = &pdev->dev;
+	struct clk_cmn_pll *cmn_pll;
 	struct clk_hw *cmn_pll_hw;
 	unsigned int num_clks;
 	struct clk_hw *hw;
@@ -388,6 +396,20 @@ static int ipq_cmn_pll_register_clks(struct platform_device *pdev)
 	if (IS_ERR(cmn_pll_hw))
 		return PTR_ERR(cmn_pll_hw);
 
+	cmn_pll = to_clk_cmn_pll(cmn_pll_hw);
+
+	/*
+	 * The CMN PLL output feeds a shared, physical /2 stage ahead of
+	 * any further per-clock processing (a gated fixed rate, a
+	 * configurable divider, or a rate-select bit). Register it once
+	 * as a fixed-factor clock so the output clock types added by
+	 * later patches can parent on it.
+	 */
+	cmn_pll->div2_hw = devm_clk_hw_register_fixed_factor_parent_hw(dev, "cmn_pll_div2",
+								       cmn_pll_hw, 0, 1, 2);
+	if (IS_ERR(cmn_pll->div2_hw))
+		return PTR_ERR(cmn_pll->div2_hw);
+
 	/* Register the fixed rate output clocks. */
 	for (i = 0; i < num_clks; i++) {
 		struct clk_parent_data pdata = { .hw = cmn_pll_hw };

-- 
2.43.0