[PATCH RFC 1/5] phy: qcom-qmp: add support for pipe clock muxing

[Johan Hovold <johan+linaro@kernel.org>]

Some QMP PHYs need to remux to their pipe clock input to the pipe clock
output generated by the PHY before powering on the PHY and restore the
default source during power down.

Add support for an optional pipe clock mux which will be reparented to
the generated pipe clock before powering on the PHY and restored to the
default reference source on power off.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++---
 1 file changed, 65 insertions(+), 6 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c
index 7d2d1ab061f7..bc6db9670291 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
@@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg {
  * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs)
  * @pcs_misc: iomapped memory space for lane's pcs_misc
  * @pipe_clk: pipe clock
+ * @pipemux_clk: pipe clock source mux
+ * @piperef_clk: pipe clock default reference source
  * @index: lane index
  * @qmp: QMP phy to which this lane belongs
  * @lane_rst: lane's reset controller
@@ -3311,6 +3313,8 @@ struct qmp_phy {
 	void __iomem *rx2;
 	void __iomem *pcs_misc;
 	struct clk *pipe_clk;
+	struct clk *pipemux_clk;
+	struct clk *piperef_clk;
 	unsigned int index;
 	struct qcom_qmp *qmp;
 	struct reset_control *lane_rst;
@@ -3346,6 +3350,7 @@ struct qcom_qmp {
 	void __iomem *dp_com;
 
 	struct clk_bulk_data *clks;
+	struct clk *pipe_clksrc;
 	struct reset_control **resets;
 	struct regulator_bulk_data *vregs;
 
@@ -5355,6 +5360,42 @@ static int qcom_qmp_phy_init(struct phy *phy)
 	return 0;
 }
 
+static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy)
+{
+	struct qcom_qmp *qmp = qphy->qmp;
+	int ret;
+
+	ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc);
+	if (ret)
+		dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret);
+
+
+	ret = clk_prepare_enable(qphy->pipe_clk);
+	if (ret) {
+		dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret);
+		goto err_restore_parent;
+	}
+
+	return 0;
+
+err_restore_parent:
+	clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk);
+
+	return ret;
+}
+
+static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy)
+{
+	struct qcom_qmp *qmp = qphy->qmp;
+	int ret;
+
+	clk_disable_unprepare(qphy->pipe_clk);
+
+	ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk);
+	if (ret)
+		dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret);
+}
+
 static int qcom_qmp_phy_power_on(struct phy *phy)
 {
 	struct qmp_phy *qphy = phy_get_drvdata(phy);
@@ -5379,11 +5420,9 @@ static int qcom_qmp_phy_power_on(struct phy *phy)
 		}
 	}
 
-	ret = clk_prepare_enable(qphy->pipe_clk);
-	if (ret) {
-		dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret);
+	ret = qcom_qmp_phy_pipe_clk_enable(qphy);
+	if (ret)
 		goto err_reset_lane;
-	}
 
 	/* Tx, Rx, and PCS configurations */
 	qcom_qmp_phy_configure_lane(tx, cfg->regs,
@@ -5478,7 +5517,7 @@ static int qcom_qmp_phy_power_on(struct phy *phy)
 	return 0;
 
 err_disable_pipe_clk:
-	clk_disable_unprepare(qphy->pipe_clk);
+	qcom_qmp_phy_pipe_clk_disable(qphy);
 err_reset_lane:
 	if (cfg->has_lane_rst)
 		reset_control_assert(qphy->lane_rst);
@@ -5491,7 +5530,7 @@ static int qcom_qmp_phy_power_off(struct phy *phy)
 	struct qmp_phy *qphy = phy_get_drvdata(phy);
 	const struct qmp_phy_cfg *cfg = qphy->cfg;
 
-	clk_disable_unprepare(qphy->pipe_clk);
+	qcom_qmp_phy_pipe_clk_disable(qphy);
 
 	if (cfg->type == PHY_TYPE_DP) {
 		/* Assert DP PHY power down */
@@ -5777,6 +5816,8 @@ static int phy_pipe_clk_register(struct qcom_qmp *qmp, struct device_node *np)
 	if (ret)
 		return ret;
 
+	qmp->pipe_clksrc = fixed->hw.clk;
+
 	ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw);
 	if (ret)
 		return ret;
@@ -6091,6 +6132,24 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id,
 		qphy->pipe_clk = NULL;
 	}
 
+	/* Get optional pipe clock mux and default reference source clock. */
+	qphy->pipemux_clk = of_clk_get_by_name(np, "mux");
+	if (IS_ERR(qphy->pipemux_clk)) {
+		ret = PTR_ERR(qphy->pipemux_clk);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		qphy->pipemux_clk = NULL;
+	} else {
+		qphy->piperef_clk = of_clk_get_by_name(np, "ref");
+		if (IS_ERR(qphy->piperef_clk)) {
+			ret = PTR_ERR(qphy->piperef_clk);
+			return dev_err_probe(dev, ret,
+					     "failed to get lane%d piperef_clk\n",
+					     id);
+		}
+	}
+
 	/* Get lane reset, if any */
 	if (cfg->has_lane_rst) {
 		snprintf(prop_name, sizeof(prop_name), "lane%d", id);
-- 
2.35.1