fpga: dfl: factor out feature device data from platform device data

Add a structure dfl_feature_dev_data to hold the DFL enumeration
info previously held in dfl_feature_platform_data. Allocate the new
structure using device-managed memory whose lifetime is bound to the
lifetime of the physical DFL, e.g., PCIe FPGA device. In a subsequent
commit, this will allow the feature platform device to be completely
destroyed and recreated on port release and assign, respectively, while
retaining the feature data in the new dfl_feature_dev_data structure.

Signed-off-by: Peter Colberg <peter.colberg@intel.com>
Reviewed-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Reviewed-by: Basheer Ahmed Muddebihal <basheer.ahmed.muddebihal@linux.intel.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20241120011035.230574-11-peter.colberg@intel.com
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>

drivers/fpga/dfl.c

@@ -752,13 +752,7 @@ binfo_create_feature_dev_data(struct build_feature_devs_info *binfo)
 	if (WARN_ON_ONCE(type >= DFL_ID_MAX))
 		return ERR_PTR(-EINVAL);
 
-	/*
+	fdata = devm_kzalloc(binfo->dev, struct_size(fdata, features, binfo->feature_num), GFP_KERNEL);
-	 * we do not need to care for the memory which is associated with
-	 * the platform device. After calling platform_device_unregister(),
-	 * it will be automatically freed by device's release() callback,
-	 * platform_device_release().
-	 */
-	fdata = kzalloc(struct_size(fdata, features, binfo->feature_num), GFP_KERNEL);
 	if (!fdata)
 		return ERR_PTR(-ENOMEM);
 
@@ -779,8 +773,6 @@ binfo_create_feature_dev_data(struct build_feature_devs_info *binfo)
 	 */
 	WARN_ON(fdata->disable_count);
 
-	fdev->dev.platform_data = fdata;
-
 	/* each sub feature has one MMIO resource */
 	fdev->num_resources = binfo->feature_num;
 	fdev->resource = kcalloc(binfo->feature_num, sizeof(*fdev->resource),
@@ -882,12 +874,18 @@ build_info_create_dev(struct build_feature_devs_info *binfo)
  */
 static int feature_dev_register(struct dfl_feature_dev_data *fdata)
 {
+	struct dfl_feature_platform_data pdata = {};
 	struct platform_device *fdev = fdata->dev;
 	int ret;
 
 	fdev->dev.parent = &fdata->dfl_cdev->region->dev;
 	fdev->dev.devt = dfl_get_devt(dfl_devs[fdata->type].devt_type, fdev->id);
 
+	pdata.fdata = fdata;
+	ret = platform_device_add_data(fdev, &pdata, sizeof(pdata));
+	if (ret)
+		return ret;
+
 	ret = platform_device_add(fdev);
 	if (ret)
 		return ret;

drivers/fpga/dfl.h

@@ -207,8 +207,7 @@
 #define PORT_UINT_CAP_INT_NUM	GENMASK_ULL(11, 0)	/* Interrupts num */
 #define PORT_UINT_CAP_FST_VECT	GENMASK_ULL(23, 12)	/* First Vector */
 
-struct dfl_feature_platform_data;
+struct dfl_feature_dev_data;
-#define dfl_feature_dev_data dfl_feature_platform_data
 
 /**
  * struct dfl_fpga_port_ops - port ops
@@ -304,26 +303,24 @@ struct dfl_feature {
 #define FEATURE_DEV_ID_UNUSED	(-1)
 
 /**
- * struct dfl_feature_platform_data - platform data for feature devices
+ * struct dfl_feature_dev_data - dfl enumeration data for dfl feature dev.
  *
- * @node: node to link feature devs to container device's port_dev_list.
+ * @node: node to link the data structure to container device's port_dev_list.
- * @lock: mutex to protect platform data.
+ * @lock: mutex to protect feature dev data.
- * @cdev: cdev of feature dev.
+ * @dev: ptr to the feature's platform device linked with this structure.
- * @dev: ptr to platform device linked with this platform data.
  * @type: type of DFL FIU for the feature dev. See enum dfl_id_type.
  * @dfl_cdev: ptr to container device.
- * @id: id used for this feature device.
+ * @id: id used for the 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.
  * @private: ptr to feature dev private data.
- * @features: sub features of this feature dev.
+ * @features: sub features for the feature dev.
  */
-struct dfl_feature_platform_data {
+struct dfl_feature_dev_data {
 	struct list_head node;
 	struct mutex lock;
-	struct cdev cdev;
 	struct platform_device *dev;
 	enum dfl_id_type type;
 	struct dfl_fpga_cdev *dfl_cdev;
@@ -336,6 +333,17 @@ struct dfl_feature_platform_data {
 	struct dfl_feature features[];
 };
 
+/**
+ * struct dfl_feature_platform_data - platform data for feature devices
+ *
+ * @cdev: cdev of feature dev.
+ * @fdata: dfl enumeration data for the dfl feature device.
+ */
+struct dfl_feature_platform_data {
+	struct cdev cdev;
+	struct dfl_feature_dev_data *fdata;
+};
+
 static inline
 int dfl_feature_dev_use_begin(struct dfl_feature_dev_data *fdata,
 			      bool excl)
@@ -404,14 +412,14 @@ int dfl_fpga_dev_ops_register(struct platform_device *pdev,
 			      struct module *owner);
 void dfl_fpga_dev_ops_unregister(struct platform_device *pdev);
 
-static inline struct dfl_feature_platform_data *
+static inline struct dfl_feature_dev_data *
 dfl_fpga_inode_to_feature_dev_data(struct inode *inode)
 {
 	struct dfl_feature_platform_data *pdata;
 
 	pdata = container_of(inode->i_cdev, struct dfl_feature_platform_data,
 			     cdev);
-	return pdata;
+	return pdata->fdata;
 }
 
 #define dfl_fpga_dev_for_each_feature(fdata, feature)			    \
@@ -442,7 +450,13 @@ dfl_get_feature_ioaddr_by_id(struct dfl_feature_dev_data *fdata, u16 id)
 	return NULL;
 }
 
-#define to_dfl_feature_dev_data dev_get_platdata
+static inline struct dfl_feature_dev_data *
+to_dfl_feature_dev_data(struct device *dev)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
+
+	return pdata->fdata;
+}
 
 static inline
 struct device *dfl_fpga_fdata_to_parent(struct dfl_feature_dev_data *fdata)