4 files changed, 67 insertions, 28 deletions

diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 65437b6a6842..435bde40f361 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c
@@ -561,14 +561,16 @@ static int afu_open(struct inode *inode, struct file *filp)
 	if (WARN_ON(!pdata))
 		return -ENODEV;
 
-	ret = dfl_feature_dev_use_begin(pdata);
-	if (ret)
-		return ret;
-
-	dev_dbg(&fdev->dev, "Device File Open\n");
-	filp->private_data = fdev;
+	mutex_lock(&pdata->lock);
+	ret = dfl_feature_dev_use_begin(pdata, filp->f_flags & O_EXCL);
+	if (!ret) {
+		dev_dbg(&fdev->dev, "Device File Opened %d Times\n",
+			dfl_feature_dev_use_count(pdata));
+		filp->private_data = fdev;
+	}
+	mutex_unlock(&pdata->lock);
 
-	return 0;
+	return ret;
 }
 
 static int afu_release(struct inode *inode, struct file *filp)
@@ -581,12 +583,14 @@ static int afu_release(struct inode *inode, struct file *filp)
 	pdata = dev_get_platdata(&pdev->dev);
 
 	mutex_lock(&pdata->lock);
-	__port_reset(pdev);
-	afu_dma_region_destroy(pdata);
-	mutex_unlock(&pdata->lock);
-
 	dfl_feature_dev_use_end(pdata);
 
+	if (!dfl_feature_dev_use_count(pdata)) {
+		__port_reset(pdev);
+		afu_dma_region_destroy(pdata);
+	}
+	mutex_unlock(&pdata->lock);
+
 	return 0;
 }
 
diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
index 1d4690c99268..56d720c1af39 100644
--- a/drivers/fpga/dfl-fme-main.c
+++ b/drivers/fpga/dfl-fme-main.c
@@ -600,14 +600,16 @@ static int fme_open(struct inode *inode, struct file *filp)
 	if (WARN_ON(!pdata))
 		return -ENODEV;
 
-	ret = dfl_feature_dev_use_begin(pdata);
-	if (ret)
-		return ret;
-
-	dev_dbg(&fdev->dev, "Device File Open\n");
-	filp->private_data = pdata;
+	mutex_lock(&pdata->lock);
+	ret = dfl_feature_dev_use_begin(pdata, filp->f_flags & O_EXCL);
+	if (!ret) {
+		dev_dbg(&fdev->dev, "Device File Opened %d Times\n",
+			dfl_feature_dev_use_count(pdata));
+		filp->private_data = pdata;
+	}
+	mutex_unlock(&pdata->lock);
 
-	return 0;
+	return ret;
 }
 
 static int fme_release(struct inode *inode, struct file *filp)
@@ -616,7 +618,10 @@ static int fme_release(struct inode *inode, struct file *filp)
 	struct platform_device *pdev = pdata->dev;
 
 	dev_dbg(&pdev->dev, "Device File Release\n");
+
+	mutex_lock(&pdata->lock);
 	dfl_feature_dev_use_end(pdata);
+	mutex_unlock(&pdata->lock);
 
 	return 0;
 }
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 96a2b8274a33..990994874bf1 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -1079,6 +1079,7 @@ static int __init dfl_fpga_init(void)
  */
 int dfl_fpga_cdev_release_port(struct dfl_fpga_cdev *cdev, int port_id)
 {
+	struct dfl_feature_platform_data *pdata;
 	struct platform_device *port_pdev;
 	int ret = -ENODEV;
 
@@ -1093,7 +1094,11 @@ int dfl_fpga_cdev_release_port(struct dfl_fpga_cdev *cdev, int port_id)
 		goto put_dev_exit;
 	}
 
-	ret = dfl_feature_dev_use_begin(dev_get_platdata(&port_pdev->dev));
+	pdata = dev_get_platdata(&port_pdev->dev);
+
+	mutex_lock(&pdata->lock);
+	ret = dfl_feature_dev_use_begin(pdata, true);
+	mutex_unlock(&pdata->lock);
 	if (ret)
 		goto put_dev_exit;
 
@@ -1120,6 +1125,7 @@ EXPORT_SYMBOL_GPL(dfl_fpga_cdev_release_port);
  */
 int dfl_fpga_cdev_assign_port(struct dfl_fpga_cdev *cdev, int port_id)
 {
+	struct dfl_feature_platform_data *pdata;
 	struct platform_device *port_pdev;
 	int ret = -ENODEV;
 
@@ -1138,7 +1144,12 @@ int dfl_fpga_cdev_assign_port(struct dfl_fpga_cdev *cdev, int port_id)
 	if (ret)
 		goto put_dev_exit;
 
-	dfl_feature_dev_use_end(dev_get_platdata(&port_pdev->dev));
+	pdata = dev_get_platdata(&port_pdev->dev);
+
+	mutex_lock(&pdata->lock);
+	dfl_feature_dev_use_end(pdata);
+	mutex_unlock(&pdata->lock);
+
 	cdev->released_port_num--;
 put_dev_exit:
 	put_device(&port_pdev->dev);
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index 9f0e656de720..4a9a33cd9979 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -205,8 +205,6 @@ struct dfl_feature {
 	const struct dfl_feature_ops *ops;
 };
 
-#define DEV_STATUS_IN_USE	0
-
 #define FEATURE_DEV_ID_UNUSED	(-1)
 
 /**
@@ -219,8 +217,9 @@ struct dfl_feature {
  * @dfl_cdev: ptr to container device.
  * @id: id used for this feature device.
  * @disable_count: count for port disable.
+ * @excl_open: set on feature device exclusive open.
+ * @open_count: count for feature device open.
  * @num: number for sub features.
- * @dev_status: dev status (e.g. DEV_STATUS_IN_USE).
  * @private: ptr to feature dev private data.
  * @features: sub features of this feature dev.
  */
@@ -232,26 +231,46 @@ struct dfl_feature_platform_data {
 	struct dfl_fpga_cdev *dfl_cdev;
 	int id;
 	unsigned int disable_count;
-	unsigned long dev_status;
+	bool excl_open;
+	int open_count;
 	void *private;
 	int num;
 	struct dfl_feature features[0];
 };
 
 static inline
-int dfl_feature_dev_use_begin(struct dfl_feature_platform_data *pdata)
+int dfl_feature_dev_use_begin(struct dfl_feature_platform_data *pdata,
+			      bool excl)
 {
-	/* Test and set IN_USE flags to ensure file is exclusively used */
-	if (test_and_set_bit_lock(DEV_STATUS_IN_USE, &pdata->dev_status))
+	if (pdata->excl_open)
 		return -EBUSY;
 
+	if (excl) {
+		if (pdata->open_count)
+			return -EBUSY;
+
+		pdata->excl_open = true;
+	}
+	pdata->open_count++;
+
 	return 0;
 }
 
 static inline
 void dfl_feature_dev_use_end(struct dfl_feature_platform_data *pdata)
 {
-	clear_bit_unlock(DEV_STATUS_IN_USE, &pdata->dev_status);
+	pdata->excl_open = false;
+
+	if (WARN_ON(pdata->open_count <= 0))
+		return;
+
+	pdata->open_count--;
+}
+
+static inline
+int dfl_feature_dev_use_count(struct dfl_feature_platform_data *pdata)
+{
+	return pdata->open_count;
 }
 
 static inline