phy: qcom: qmp-pcie: register second optional PHY AUX clock

The PCIe Gen4x2 PHY found in the SM8[456]50 SoCs have a second clock,
add the code to register it for PHYs configs that sets a aux_clock_rate.

In order to get the right clock, add qmp_pcie_clk_hw_get() which uses
the newly introduced QMP_PCIE_PIPE_CLK & QMP_PCIE_PHY_AUX_CLK clock
IDs and also supports the legacy bindings by returning the PIPE clock
when #clock-cells=0.

Signed-off-by: Neil Armstrong <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/r/20240322-topic-sm8x50-upstream-pcie-1-phy-aux-clk-v2-3-3ec0a966d52f@linaro.org
Signed-off-by: Vinod Koul <[email protected]>

Author: superna9999

drivers/phy/qualcomm/phy-qcom-qmp-pcie.c

@@ -22,6 +22,8 @@
 #include <linux/reset.h>
 #include <linux/slab.h>
 
+#include <dt-bindings/phy/phy-qcom-qmp.h>
+
 #include "phy-qcom-qmp-common.h"
 
 #include "phy-qcom-qmp.h"
@@ -2389,6 +2391,9 @@ struct qmp_phy_cfg {
 
 	/* QMP PHY pipe clock interface rate */
 	unsigned long pipe_clock_rate;
+
+	/* QMP PHY AUX clock interface rate */
+	unsigned long aux_clock_rate;
 };
 
 struct qmp_pcie {
@@ -2420,6 +2425,7 @@ struct qmp_pcie {
 	int mode;
 
 	struct clk_fixed_rate pipe_clk_fixed;
+	struct clk_fixed_rate aux_clk_fixed;
 };
 
 static inline void qphy_setbits(void __iomem *base, u32 offset, u32 val)
@@ -3686,6 +3692,62 @@ static int phy_pipe_clk_register(struct qmp_pcie *qmp, struct device_node *np)
 	return devm_clk_hw_register(qmp->dev, &fixed->hw);
 }
 
+/*
+ * Register a fixed rate PHY aux clock.
+ *
+ * The <s>_phy_aux_clksrc generated by PHY goes to the GCC that gate
+ * controls it. The <s>_phy_aux_clk coming out of the GCC is requested
+ * by the PHY driver for its operations.
+ * We register the <s>_phy_aux_clksrc here. The gcc driver takes care
+ * of assigning this <s>_phy_aux_clksrc as parent to <s>_phy_aux_clk.
+ * Below picture shows this relationship.
+ *
+ *         +---------------+
+ *         |   PHY block   |<<---------------------------------------------+
+ *         |               |                                               |
+ *         |   +-------+   |                      +-----+                  |
+ *   I/P---^-->|  PLL  |---^--->phy_aux_clksrc--->| GCC |--->phy_aux_clk---+
+ *    clk  |   +-------+   |                      +-----+
+ *         +---------------+
+ */
+static int phy_aux_clk_register(struct qmp_pcie *qmp, struct device_node *np)
+{
+	struct clk_fixed_rate *fixed = &qmp->aux_clk_fixed;
+	struct clk_init_data init = { };
+	int ret;
+
+	ret = of_property_read_string_index(np, "clock-output-names", 1, &init.name);
+	if (ret) {
+		dev_err(qmp->dev, "%pOFn: No clock-output-names index 1\n", np);
+		return ret;
+	}
+
+	init.ops = &clk_fixed_rate_ops;
+
+	fixed->fixed_rate = qmp->cfg->aux_clock_rate;
+	fixed->hw.init = &init;
+
+	return devm_clk_hw_register(qmp->dev, &fixed->hw);
+}
+
+static struct clk_hw *qmp_pcie_clk_hw_get(struct of_phandle_args *clkspec, void *data)
+{
+	struct qmp_pcie *qmp = data;
+
+	/* Support legacy bindings */
+	if (!clkspec->args_count)
+		return &qmp->pipe_clk_fixed.hw;
+
+	switch (clkspec->args[0]) {
+	case QMP_PCIE_PIPE_CLK:
+		return &qmp->pipe_clk_fixed.hw;
+	case QMP_PCIE_PHY_AUX_CLK:
+		return &qmp->aux_clk_fixed.hw;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
 static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np)
 {
 	int ret;
@@ -3694,9 +3756,19 @@ static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np
 	if (ret)
 		return ret;
 
-	ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &qmp->pipe_clk_fixed.hw);
-	if (ret)
-		return ret;
+	if (qmp->cfg->aux_clock_rate) {
+		ret = phy_aux_clk_register(qmp, np);
+		if (ret)
+			return ret;
+
+		ret = of_clk_add_hw_provider(np, qmp_pcie_clk_hw_get, qmp);
+		if (ret)
+			return ret;
+	} else {
+		ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &qmp->pipe_clk_fixed.hw);
+		if (ret)
+			return ret;
+	}
 
 	/*
 	 * Roll a devm action because the clock provider is the child node, but