1 files changed, 39 insertions, 5 deletions

diff --git a/drivers/i2c/busses/i2c-mlxbf.c b/drivers/i2c/busses/i2c-mlxbf.c
index 1a0fc9640c23..78b2bc9b0a34 100644
--- a/drivers/i2c/busses/i2c-mlxbf.c
+++ b/drivers/i2c/busses/i2c-mlxbf.c
@@ -306,6 +306,7 @@ static u64 mlxbf_i2c_corepll_frequency;
  * exact.
  */
 #define MLXBF_I2C_SMBUS_TIMEOUT   (300 * 1000) /* 300ms */
+#define MLXBF_I2C_SMBUS_LOCK_POLL_TIMEOUT (300 * 1000) /* 300ms */
 
 /* Encapsulates timing parameters. */
 struct mlxbf_i2c_timings {
@@ -514,6 +515,25 @@ static bool mlxbf_smbus_master_wait_for_idle(struct mlxbf_i2c_priv *priv)
 	return false;
 }
 
+/*
+ * wait for the lock to be released before acquiring it.
+ */
+static bool mlxbf_i2c_smbus_master_lock(struct mlxbf_i2c_priv *priv)
+{
+	if (mlxbf_smbus_poll(priv->smbus->io, MLXBF_I2C_SMBUS_MASTER_GW,
+			   MLXBF_I2C_MASTER_LOCK_BIT, true,
+			   MLXBF_I2C_SMBUS_LOCK_POLL_TIMEOUT))
+		return true;
+
+	return false;
+}
+
+static void mlxbf_i2c_smbus_master_unlock(struct mlxbf_i2c_priv *priv)
+{
+	/* Clear the gw to clear the lock */
+	writel(0, priv->smbus->io + MLXBF_I2C_SMBUS_MASTER_GW);
+}
+
 static bool mlxbf_i2c_smbus_transaction_success(u32 master_status,
 						u32 cause_status)
 {
@@ -705,10 +725,19 @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
 	slave = request->slave & GENMASK(6, 0);
 	addr = slave << 1;
 
-	/* First of all, check whether the HW is idle. */
-	if (WARN_ON(!mlxbf_smbus_master_wait_for_idle(priv)))
+	/*
+	 * Try to acquire the smbus gw lock before any reads of the GW register since
+	 * a read sets the lock.
+	 */
+	if (WARN_ON(!mlxbf_i2c_smbus_master_lock(priv)))
 		return -EBUSY;
 
+	/* Check whether the HW is idle */
+	if (WARN_ON(!mlxbf_smbus_master_wait_for_idle(priv))) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
 	/* Set first byte. */
 	data_desc[data_idx++] = addr;
 
@@ -732,8 +761,10 @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
 			write_en = 1;
 			write_len += operation->length;
 			if (data_idx + operation->length >
-					MLXBF_I2C_MASTER_DATA_DESC_SIZE)
-				return -ENOBUFS;
+					MLXBF_I2C_MASTER_DATA_DESC_SIZE) {
+				ret = -ENOBUFS;
+				goto out_unlock;
+			}
 			memcpy(data_desc + data_idx,
 			       operation->buffer, operation->length);
 			data_idx += operation->length;
@@ -765,7 +796,7 @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
 		ret = mlxbf_i2c_smbus_enable(priv, slave, write_len, block_en,
 					 pec_en, 0);
 		if (ret)
-			return ret;
+			goto out_unlock;
 	}
 
 	if (read_en) {
@@ -792,6 +823,9 @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
 			priv->smbus->io + MLXBF_I2C_SMBUS_MASTER_FSM);
 	}
 
+out_unlock:
+	mlxbf_i2c_smbus_master_unlock(priv);
+
 	return ret;
 }