[PATCH V2] scsi: ufs: ufs-qcom: Enable only lane clocks in lane clock APIs

[Nitin Rawat <nitin.rawat@oss.qualcomm.com>]

ufs_qcom_enable_lane_clks() and ufs_qcom_disable_lane_clks() currently
use clk_bulk_prepare_enable()/clk_bulk_disable_unprepare() on the
entire host->clks array obtained from devm_clk_bulk_get_all(). This
array contains all device clocks, not just lane symbol clocks.

Since the UFS core framework already manages the non-lane clocks via
the setup_clocks callback, the bulk enable/disable in the lane clock
APIs resulted in duplicate reference count increments on those shared
clocks. The extra enable counts were never balanced by a corresponding
disable from the framework's clock gating path, preventing the clock
reference counts from reaching zero and ultimately blocking CXO
shutdown during low-power states.

Fix this by restricting the lane clock APIs to only prepare/enable
and disable/unprepare the three lane symbol clocks (tx_lane0_sync_clk,
rx_lane0_sync_clk, rx_lane1_sync_clk), leaving the handling of all
other clocks to the UFS core framework. The lane clocks are now
acquired individually via devm_clk_get() instead of being looked up
in the bulk clock array.

Signed-off-by: Nitin Rawat <nitin.rawat@oss.qualcomm.com>
---
Changes from v1:
1. As per konrad's comment, used devm_clk_get instead of to get
   lane clock handle instead of using bulk call API.
---
 drivers/ufs/host/ufs-qcom.c | 47 ++++++++++++++++++++++++++++++-------
 drivers/ufs/host/ufs-qcom.h |  5 ++--
 2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index aa2ac2cd2b69..50f34d1c5fdb 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -348,7 +348,9 @@ static void ufs_qcom_disable_lane_clks(struct ufs_qcom_host *host)
 	if (!host->is_lane_clks_enabled)
 		return;

-	clk_bulk_disable_unprepare(host->num_clks, host->clks);
+	clk_disable_unprepare(host->rx_lane1_sync_clk);
+	clk_disable_unprepare(host->rx_lane0_sync_clk);
+	clk_disable_unprepare(host->tx_lane0_sync_clk);

 	host->is_lane_clks_enabled = false;
 }
@@ -357,28 +359,57 @@ static int ufs_qcom_enable_lane_clks(struct ufs_qcom_host *host)
 {
 	int err;

-	err = clk_bulk_prepare_enable(host->num_clks, host->clks);
+	if (host->is_lane_clks_enabled)
+		return 0;
+
+	err = clk_prepare_enable(host->tx_lane0_sync_clk);
 	if (err)
-		return err;
+		goto out;
+
+	err = clk_prepare_enable(host->rx_lane0_sync_clk);
+	if (err)
+		goto out_disable_tx_lane0;
+
+	err = clk_prepare_enable(host->rx_lane1_sync_clk);
+	if (err)
+		goto out_disable_rx_lane0;

 	host->is_lane_clks_enabled = true;

 	return 0;
+
+out_disable_rx_lane0:
+	clk_disable_unprepare(host->rx_lane0_sync_clk);
+out_disable_tx_lane0:
+	clk_disable_unprepare(host->tx_lane0_sync_clk);
+out:
+	return err;
 }

 static int ufs_qcom_init_lane_clks(struct ufs_qcom_host *host)
 {
-	int err;
 	struct device *dev = host->hba->dev;

 	if (has_acpi_companion(dev))
 		return 0;

-	err = devm_clk_bulk_get_all(dev, &host->clks);
-	if (err <= 0)
-		return err;
+	host->tx_lane0_sync_clk = devm_clk_get(dev, "tx_lane0_sync_clk");
+	if (IS_ERR(host->tx_lane0_sync_clk))
+		return dev_err_probe(dev, PTR_ERR(host->tx_lane0_sync_clk),
+				     "failed to get tx_lane0_sync_clk\n");
+
+	host->rx_lane0_sync_clk = devm_clk_get(dev, "rx_lane0_sync_clk");
+	if (IS_ERR(host->rx_lane0_sync_clk))
+		return dev_err_probe(dev, PTR_ERR(host->rx_lane0_sync_clk),
+				     "failed to get rx_lane0_sync_clk\n");

-	host->num_clks = err;
+	/* In case of single lane per direction, don't read lane1 clocks */
+	if (host->hba->lanes_per_direction > 1) {
+		host->rx_lane1_sync_clk = devm_clk_get(dev, "rx_lane1_sync_clk");
+		if (IS_ERR(host->rx_lane1_sync_clk))
+			return dev_err_probe(dev, PTR_ERR(host->rx_lane1_sync_clk),
+					     "failed to get rx_lane1_sync_clk\n");
+	}

 	return 0;
 }
diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
index e20b3ca50577..37f6e88b0adf 100644
--- a/drivers/ufs/host/ufs-qcom.h
+++ b/drivers/ufs/host/ufs-qcom.h
@@ -330,8 +330,9 @@ struct ufs_qcom_host {
 	struct phy *generic_phy;
 	struct ufs_hba *hba;
 	struct ufs_pa_layer_attr dev_req_params;
-	struct clk_bulk_data *clks;
-	u32 num_clks;
+	struct clk *tx_lane0_sync_clk;
+	struct clk *rx_lane0_sync_clk;
+	struct clk *rx_lane1_sync_clk;
 	bool is_lane_clks_enabled;

 	struct icc_path *icc_ddr;
--
2.34.1