[PATCH v3 4/4] PCIe: qcom: Add support to control pipe clk mux

[Prasad Malisetty <pmaliset@codeaurora.org>]

pipe-clk mux needs to switch between pipe_clk
and XO as part of LPM squence. This is done by setting
pipe_clk mux as parent of pipe_clk after phy init.
This is a new requirement for sc7280.
For accessing to DBI registers during L23,
need to switch the pipe clock with free-running
clock (TCXO) using GCC’s registers

Signed-off-by: Prasad Malisetty <pmaliset@codeaurora.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 8a7a300..80e9ee4 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -166,6 +166,9 @@ struct qcom_pcie_resources_2_7_0 {
 	struct regulator_bulk_data supplies[2];
 	struct reset_control *pci_reset;
 	struct clk *pipe_clk;
+	struct clk *pipe_clk_mux;
+	struct clk *pipe_ext_src;
+	struct clk *ref_clk_src;
 };
 
 union qcom_pcie_resources {
@@ -1167,6 +1170,20 @@ static int qcom_pcie_get_resources_2_7_0(struct qcom_pcie *pcie)
 	if (ret < 0)
 		return ret;
 
+	if (of_device_is_compatible(dev->of_node, "qcom,pcie-sc7280")) {
+		res->pipe_clk_mux = devm_clk_get(dev, "pipe_mux");
+		if (IS_ERR(res->pipe_clk_mux))
+			return PTR_ERR(res->pipe_clk_mux);
+
+		res->pipe_ext_src = devm_clk_get(dev, "phy_pipe");
+		if (IS_ERR(res->pipe_ext_src))
+			return PTR_ERR(res->pipe_ext_src);
+
+		res->ref_clk_src = devm_clk_get(dev, "ref");
+		if (IS_ERR(res->ref_clk_src))
+			return PTR_ERR(res->ref_clk_src);
+	}
+
 	res->pipe_clk = devm_clk_get(dev, "pipe");
 	return PTR_ERR_OR_ZERO(res->pipe_clk);
 }
@@ -1255,6 +1272,11 @@ static void qcom_pcie_deinit_2_7_0(struct qcom_pcie *pcie)
 static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
+	struct dw_pcie *pci = pcie->pci;
+	struct device *dev = pci->dev;
+
+	if (of_device_is_compatible(dev->of_node, "qcom,pcie-sc7280"))
+		clk_set_parent(res->pipe_clk_mux, res->pipe_ext_src);
 
 	return clk_prepare_enable(res->pipe_clk);
 }
-- 
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