[PATCH v6 2/2] scsi: ufs: core: Add support for static TX Equalization settings

[Can Guo]

Static TX Equalization settings and TX Precode enable indication from DT
properties txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6], and
tx-precode-enable-g6 are board-specific baseline values. Values are
provided as per-lane tuples:

<Host_Lane0 Device_Lane0>, [<Host_Lane1 Device_Lane1>]

Parse DT u32 properties with explicit range checks by using
of_property_count_u32_elems()/of_property_read_u32_array().

When adaptive TX Equalization is used, these static settings are not final:

- If valid settings are retrieved from qTxEQGnSettings/wTxEQGnSettingsExt,
  those retrieved settings override static DT settings.
- If retrieval is not available/valid, TX EQTR runs and trained settings
  override static DT settings.

So static DT settings are a fallback and are intended for cases where
adaptive TX Equalization is not enabled/used. Adaptive TX Equalization
remains the primary path when enabled.

No behavior changes for platforms that do not provide these properties.

Reviewed-by: Bean Huo <beanhuo@xxxxxxxxxx>
Signed-off-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
---
 drivers/ufs/core/ufs-txeq.c      |  10 ++-
 drivers/ufs/host/ufshcd-pltfrm.c | 139 +++++++++++++++++++++++++++++++
 include/ufs/ufshcd.h             |   2 +
 3 files changed, 150 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufs-txeq.c b/drivers/ufs/core/ufs-txeq.c
index 4b264adfdf49..b645fe5f6d95 100644
--- a/drivers/ufs/core/ufs-txeq.c
+++ b/drivers/ufs/core/ufs-txeq.c
@@ -1297,7 +1297,13 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
 	}
 
 	params = &hba->tx_eq_params[gear - 1];
-	if (!params->is_valid || force_tx_eqtr) {
+	/*
+	 * TX EQTR must run for the following cases:
+	 * 1. TX EQ settings are invalid.
+	 * 2. TX EQ settings are valid but static, i.e., populated from DT.
+	 * 3. TX EQTR procedure is forced.
+	 */
+	if (!params->is_valid || params->is_static || force_tx_eqtr) {
 		int ret;
 
 		ret = ufshcd_tx_eqtr(hba, params, pwr_mode);
@@ -1310,6 +1316,7 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
 		/* Mark TX Equalization settings as valid */
 		params->is_valid = true;
 		params->is_trained = true;
+		params->is_static = false;
 		params->is_applied = false;
 	}
 
@@ -1495,6 +1502,7 @@ static void ufshcd_extract_tx_eq_settings_attrs(struct ufs_hba *hba, u8 gear)
 	}
 
 	params->is_valid = true;
+	params->is_static = false;
 }
 
 void ufshcd_retrieve_tx_eq_settings(struct ufs_hba *hba)
diff --git a/drivers/ufs/host/ufshcd-pltfrm.c b/drivers/ufs/host/ufshcd-pltfrm.c
index c2dafb583cf5..fc6aa91b6210 100644
--- a/drivers/ufs/host/ufshcd-pltfrm.c
+++ b/drivers/ufs/host/ufshcd-pltfrm.c
@@ -210,6 +210,143 @@ static void ufshcd_init_lanes_per_dir(struct ufs_hba *hba)
 	}
 }
 
+/**
+ * ufshcd_parse_tx_eq_settings_for_gear - Parse static TX EQ DT settings for one gear
+ * @hba: per adapter instance
+ * @gear: target HS gear
+ * @num_elems: expected number of elements per property
+ *
+ * Reads the txeq-preshoot-gN, txeq-deemphasis-gN, and (for G6)
+ * tx-precode-enable-gN device-tree properties and, if all are valid, stores
+ * them as static TX Equalization settings for the given gear.
+ */
+static void ufshcd_parse_tx_eq_settings_for_gear(struct ufs_hba *hba,
+						 int gear, const u32 num_elems)
+{
+	u32 precode_en[UFS_MAX_LANES * 2] = { 0 };
+	const u32 lpd = hba->lanes_per_direction;
+	struct ufshcd_tx_eq_params *params;
+	u32 deemphasis[UFS_MAX_LANES * 2];
+	u32 preshoot[UFS_MAX_LANES * 2];
+	struct device *dev = hba->dev;
+	char prop_name[MAX_PROP_SIZE];
+	int i, err, lane, count;
+
+	snprintf(prop_name, MAX_PROP_SIZE, "txeq-preshoot-g%d", gear);
+	count = of_property_count_u32_elems(dev->of_node, prop_name);
+	if (count <= 0)
+		return;
+
+	if (count != num_elems) {
+		dev_err(dev, "Property %s has invalid count (%d), expecting %u\n",
+			prop_name, count, num_elems);
+		return;
+	}
+
+	err = of_property_read_u32_array(dev->of_node, prop_name, preshoot, num_elems);
+	if (err) {
+		dev_err(dev, "Failed to read %s property, %d\n", prop_name, err);
+		return;
+	}
+
+	for (i = 0; i < num_elems; i++) {
+		if (preshoot[i] >= TX_HS_NUM_PRESHOOT) {
+			dev_err(dev, "An invalid TX EQ PreShoot (%d) provided in %s property\n",
+				preshoot[i], prop_name);
+			return;
+		}
+	}
+
+	snprintf(prop_name, MAX_PROP_SIZE, "txeq-deemphasis-g%d", gear);
+	count = of_property_count_u32_elems(dev->of_node, prop_name);
+	if (count <= 0) {
+		dev_err(dev, "Missing required %s property\n", prop_name);
+		return;
+	}
+
+	if (count != num_elems) {
+		dev_err(dev, "Property %s has invalid count (%d), expecting %u\n",
+			prop_name, count, num_elems);
+		return;
+	}
+
+	err = of_property_read_u32_array(dev->of_node, prop_name, deemphasis, num_elems);
+	if (err) {
+		dev_err(dev, "Failed to read %s property, %d\n", prop_name, err);
+		return;
+	}
+
+	for (i = 0; i < num_elems; i++) {
+		if (deemphasis[i] >= TX_HS_NUM_DEEMPHASIS) {
+			dev_err(dev, "An invalid TX EQ DeEmphasis (%d) provided in %s property\n",
+				deemphasis[i], prop_name);
+			return;
+		}
+	}
+
+	if (gear == UFS_HS_G6) {
+		snprintf(prop_name, MAX_PROP_SIZE, "tx-precode-enable-g%d", gear);
+		count = of_property_count_u32_elems(dev->of_node, prop_name);
+		if (count > 0) {
+			if (count != num_elems) {
+				dev_err(dev, "Property %s has invalid count (%d), expecting %u\n",
+					prop_name, count, num_elems);
+				return;
+			}
+
+			err = of_property_read_u32_array(dev->of_node, prop_name,
+							 precode_en, num_elems);
+			if (err) {
+				dev_err(dev, "Failed to read %s property, %d\n",
+					prop_name, err);
+				return;
+			}
+
+			for (i = 0; i < num_elems; i++) {
+				if (precode_en[i] > 1) {
+					dev_err(dev, "An invalid PrecodeEn (%d) provided in %s property\n",
+						precode_en[i], prop_name);
+					return;
+				}
+			}
+		}
+	}
+
+	params = &hba->tx_eq_params[gear - 1];
+	for (lane = 0; lane < lpd; lane++) {
+		params->host[lane].preshoot = preshoot[lane * 2];
+		params->host[lane].deemphasis = deemphasis[lane * 2];
+		params->host[lane].precode_en = precode_en[lane * 2];
+
+		params->device[lane].preshoot = preshoot[lane * 2 + 1];
+		params->device[lane].deemphasis = deemphasis[lane * 2 + 1];
+		params->device[lane].precode_en = precode_en[lane * 2 + 1];
+	}
+
+	params->is_valid = true;
+	params->is_static = true;
+}
+
+static void ufshcd_parse_static_tx_eq_settings(struct ufs_hba *hba)
+{
+	const u32 lpd = hba->lanes_per_direction;
+	const u32 num_elems = lpd * 2;
+	int gear;
+
+	if (!lpd) {
+		return;
+	}
+
+	if (lpd > UFS_MAX_LANES) {
+		dev_warn(hba->dev, "lanes_per_direction (%u) exceeds UFS_MAX_LANES (%u)\n",
+			 lpd, UFS_MAX_LANES);
+		return;
+	}
+
+	for (gear = UFS_HS_G1; gear <= UFS_HS_GEAR_MAX; gear++)
+		ufshcd_parse_tx_eq_settings_for_gear(hba, gear, num_elems);
+}
+
 /**
  * ufshcd_parse_clock_min_max_freq  - Parse MIN and MAX clocks freq
  * @hba: per adapter instance
@@ -528,6 +665,8 @@ int ufshcd_pltfrm_init(struct platform_device *pdev,
 
 	ufshcd_init_lanes_per_dir(hba);
 
+	ufshcd_parse_static_tx_eq_settings(hba);
+
 	err = ufshcd_parse_operating_points(hba);
 	if (err) {
 		dev_err(dev, "%s: OPP parse failed %d\n", __func__, err);
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index f48d6416e299..c01824576472 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -359,6 +359,7 @@ struct ufshcd_tx_eqtr_record {
  * @is_valid: True if parameter contains valid TX Equalization settings
  * @is_applied: True if settings have been applied to UniPro of both sides
  * @is_trained: True if parameters obtained from TX EQTR procedure
+ * @is_static: True if settings are static
  */
 struct ufshcd_tx_eq_params {
 	struct ufshcd_tx_eq_settings host[UFS_MAX_LANES];
@@ -367,6 +368,7 @@ struct ufshcd_tx_eq_params {
 	bool is_valid;
 	bool is_applied;
 	bool is_trained;
+	bool is_static;
 };
 
 /**
-- 
2.34.1