[PATCH v2 07/12] clk: qcom: ipq-cmn-pll: Add PON reference clock support

The PON (Passive Optical Network) reference clock is derived from the
CMN PLL output divided by 2 and then further divided by a configurable
8-bit divider (1-255). The clock supports two modes:

- UNIPHY mode (CMN_PLL_PON_MODE_SEL = 0): fixed 31.25 MHz output
- PON mode   (CMN_PLL_PON_MODE_SEL = 1): pll_rate / (2 * divider)

The clock output can be independently enabled and disabled via the
CMN_PLL_PON_EN bit.

Signed-off-by: Luo Jie <[email protected]>
---
 drivers/clk/qcom/ipq-cmn-pll.c | 171 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)

diff --git a/drivers/clk/qcom/ipq-cmn-pll.c b/drivers/clk/qcom/ipq-cmn-pll.c
index a24e57b33c6b..356988c03a7a 100644
--- a/drivers/clk/qcom/ipq-cmn-pll.c
+++ b/drivers/clk/qcom/ipq-cmn-pll.c
@@ -73,6 +73,11 @@
 #define CMN_PLL_NSS_CLK_SEL			GENMASK(13, 8)
 #define CMN_PLL_PPE_CLK_SEL			GENMASK(5, 0)
 
+#define CMN_PLL_PON_CONFIG			0x42c
+#define CMN_PLL_PON_MODE_SEL			BIT(9)
+#define CMN_PLL_PON_EN				BIT(8)
+#define CMN_PLL_PON_DIV_CTRL			GENMASK(7, 0)
+
 #define CMN_PLL_POWER_ON_AND_RESET		0x780
 #define CMN_ANA_EN_SW_RSTN			BIT(6)
 
@@ -92,11 +97,13 @@
  * @CMN_PLL_CLK_FIXED_RATE: plain fixed rate clock
  * @CMN_PLL_CLK_NSS: NSS clock with configurable divider
  * @CMN_PLL_CLK_PPE: PPE clock with configurable divider
+ * @CMN_PLL_CLK_PON: PON reference clock
  */
 enum cmn_pll_clk_type {
 	CMN_PLL_CLK_FIXED_RATE,
 	CMN_PLL_CLK_NSS,
 	CMN_PLL_CLK_PPE,
+	CMN_PLL_CLK_PON,
 };
 
 /**
@@ -413,6 +420,164 @@ static struct clk_hw *ipq_cmn_pll_regmap_div_register(struct platform_device *pd
 	return &div_clk->clkr.hw;
 }
 
+/*
+ * PON (Passive Optical Network) reference clock operations.
+ * The PON refclk is derived from CMN PLL rate / 2, then divided by
+ * a configurable 8-bit divider (1-255).
+ */
+static int clk_pon_refclk_enable(struct clk_hw *hw)
+{
+	struct clk_cmn_pll *pon_clk = to_clk_cmn_pll(hw);
+
+	return regmap_set_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+			       CMN_PLL_PON_EN);
+}
+
+static void clk_pon_refclk_disable(struct clk_hw *hw)
+{
+	struct clk_cmn_pll *pon_clk = to_clk_cmn_pll(hw);
+
+	regmap_clear_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+			  CMN_PLL_PON_EN);
+}
+
+static int clk_pon_refclk_is_enabled(struct clk_hw *hw)
+{
+	struct clk_cmn_pll *pon_clk = to_clk_cmn_pll(hw);
+
+	return regmap_test_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+				CMN_PLL_PON_EN);
+}
+
+static unsigned long clk_pon_refclk_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct clk_cmn_pll *pon_clk = to_clk_cmn_pll(hw);
+	u32 val, div;
+	int ret;
+
+	ret = regmap_read(pon_clk->regmap, CMN_PLL_PON_CONFIG, &val);
+	if (WARN_ON_ONCE(ret))
+		return 0;
+
+	/* Check if in UNIPHY mode (bit 9 = 0) - fixed 31.25 MHz */
+	if (!(val & CMN_PLL_PON_MODE_SEL))
+		return 31250000UL;
+
+	/* PON mode: calculate from divider */
+	div = FIELD_GET(CMN_PLL_PON_DIV_CTRL, val);
+	if (WARN_ON_ONCE(!div))
+		return 0;
+
+	return DIV_ROUND_CLOSEST_ULL((u64)parent_rate, 2ULL * div);
+}
+
+static int clk_pon_refclk_determine_rate(struct clk_hw *hw,
+					 struct clk_rate_request *req)
+{
+	unsigned long div, pon_rate, uniphy_rate = 31250000UL;
+
+	if (WARN_ON_ONCE(!req->rate))
+		return -EINVAL;
+
+	div = DIV64_U64_ROUND_CLOSEST((u64)req->best_parent_rate, 2ULL * req->rate);
+
+	/* Clamp to valid range (1-255) */
+	div = clamp_t(unsigned long, div, 1, 255);
+
+	pon_rate = DIV_ROUND_CLOSEST_ULL((u64)req->best_parent_rate, 2ULL * div);
+
+	/* Pick whichever mode gets closer to the requested rate */
+	req->rate = abs_diff(req->rate, uniphy_rate) < abs_diff(req->rate, pon_rate) ?
+		    uniphy_rate : pon_rate;
+
+	return 0;
+}
+
+static int clk_pon_refclk_set_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long parent_rate)
+{
+	struct clk_cmn_pll *pon_clk = to_clk_cmn_pll(hw);
+	unsigned long div;
+	int ret;
+
+	if (rate == 0)
+		return -EINVAL;
+
+	/*
+	 * An exact request for 31.25 MHz is always satisfiable by UNIPHY
+	 * mode, even though PON mode with a suitable divider can produce
+	 * the same frequency for some parent rates. Preferring UNIPHY here
+	 * is safe: this function is only ever called with a rate produced
+	 * by clk_pon_refclk_determine_rate() through the standard
+	 * clk_set_rate() path, and either mode yields the identical output
+	 * rate for this value.
+	 */
+	if (rate == 31250000UL)
+		return regmap_clear_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+					 CMN_PLL_PON_MODE_SEL);
+
+	div = DIV64_U64_ROUND_CLOSEST((u64)parent_rate, 2ULL * rate);
+	if (div == 0 || div > 255)
+		return -EINVAL;
+
+	/* Switch to PON mode */
+	ret = regmap_set_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+			      CMN_PLL_PON_MODE_SEL);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(pon_clk->regmap, CMN_PLL_PON_CONFIG,
+				  CMN_PLL_PON_DIV_CTRL,
+				  FIELD_PREP(CMN_PLL_PON_DIV_CTRL, div));
+}
+
+static const struct clk_ops clk_pon_refclk_ops = {
+	.enable = clk_pon_refclk_enable,
+	.disable = clk_pon_refclk_disable,
+	.is_enabled = clk_pon_refclk_is_enabled,
+	.recalc_rate = clk_pon_refclk_recalc_rate,
+	.determine_rate = clk_pon_refclk_determine_rate,
+	.set_rate = clk_pon_refclk_set_rate,
+};
+
+static struct clk_hw *ipq_cmn_pll_pon_refclk_register(struct platform_device *pdev,
+						      struct regmap *regmap,
+						      struct clk_hw *cmn_pll_hw,
+						      const char *name)
+{
+	struct clk_parent_data pdata = { .hw = cmn_pll_hw };
+	struct device *dev = &pdev->dev;
+	struct clk_init_data init = {};
+	struct clk_cmn_pll *pon_clk;
+	int ret;
+
+	pon_clk = devm_kzalloc(dev, sizeof(*pon_clk), GFP_KERNEL);
+	if (!pon_clk)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.parent_data = &pdata;
+	init.num_parents = 1;
+	init.ops = &clk_pon_refclk_ops;
+	/*
+	 * The PON reference clock may already be enabled by bootloader
+	 * or consumed by hardware without an in-kernel client driver.
+	 * Add CLK_IGNORE_UNUSED so the clock framework does not disable
+	 * it when no consumer has claimed it.
+	 */
+	init.flags = CLK_IGNORE_UNUSED;
+
+	pon_clk->hw.init = &init;
+	pon_clk->regmap = regmap;
+
+	ret = devm_clk_hw_register(dev, &pon_clk->hw);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return &pon_clk->hw;
+}
+
 static int ipq_cmn_pll_register_clks(struct platform_device *pdev)
 {
 	const struct cmn_pll_fixed_output_clk *p, *fixed_clk;
@@ -473,6 +638,12 @@ static int ipq_cmn_pll_register_clks(struct platform_device *pdev)
 							     fixed_clk[i].name,
 							     CMN_PLL_PPE_CLK_SEL);
 			break;
+		case CMN_PLL_CLK_PON:
+			hw = ipq_cmn_pll_pon_refclk_register(pdev,
+							     cmn_pll->regmap,
+							     cmn_pll_hw,
+							     fixed_clk[i].name);
+			break;
 		}
 
 		if (IS_ERR(hw))

-- 
2.43.0