[PATCH v9 3/3] fpga: region: Use standard dev_release for class driver

[Russ Weight <russell.h.weight@intel.com>]

The FPGA region class driver data structure is being treated as a
managed resource instead of using the standard dev_release call-back
function to release the class data structure. This change removes the
managed resource code and combines the create() and register()
functions into a single register() or register_simple() function.

The register() function accepts an info data structure to provide
flexibility in passing optional parameters. The register_simple()
function supports the current parameter list for users that don't
require the use of optional parameters.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
---
v9:
  - Cleaned up documentation for the FPGA Region register functions
  - Renamed fpga_region_register() to fpga_region_register_full()
  - Renamed fpga_region_register_simple() to fpga_region_register()
v8:
  - Added reviewed-by tag.
  - Updated Documentation/driver-api/fpga/fpga-region.rst documentation.
v7:
  - Update the commit message to describe the new parameters for the
    fpga_region_register() function and to mention the
    fpga_region_register_simple() function.
  - Fix function prototypes in header file to rename dev to parent.
  - Some cleanup of comments.
  - Update function defintions/prototypes to apply const to the new info
    parameter.
  - Verify a non-null info pointer in the register() functions.
v6:
  - Moved FPGA manager optional parameters out of the ops structure and
    back into the FPGA Region structure.
  - Changed fpga_region_register() parameters to accept an info data
    structure to provide flexibility in passing optional parameters.
  - Added fpga_region_register_simple() functions to support current
    parameters for users that don't require the use of optional parameters.
v5:
  - Rebased on top of recently accepted patches.
  - Created the fpga_region_ops data structure which is optionally passed
    to fpga_region_register(). compat_id, the get_bridges() pointer, and
    the priv pointer are included in the fpga_region_ops structure.
v4:
  - Added the compat_id parameter to fpga_region_register() to ensure
    that the compat_id is set before the device_register() call.
  - Modified the dfl_fpga_feature_devs_enumerate() function to restore
    the fpga_region_register() call to the correct location.
v3:
  - Cleaned up comment header for fpga_region_register()
  - Fix fpga_region_register() error return on ida_simple_get() failure
v2:
  - No changes
---
 Documentation/driver-api/fpga/fpga-region.rst |   8 +-
 drivers/fpga/dfl-fme-region.c                 |  17 ++-
 drivers/fpga/dfl.c                            |  12 +-
 drivers/fpga/fpga-region.c                    | 119 +++++++-----------
 drivers/fpga/of-fpga-region.c                 |  10 +-
 include/linux/fpga/fpga-region.h              |  36 ++++--
 6 files changed, 91 insertions(+), 111 deletions(-)

diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst
index 2636a27c11b2..904518190bb4 100644
--- a/Documentation/driver-api/fpga/fpga-region.rst
+++ b/Documentation/driver-api/fpga/fpga-region.rst
@@ -46,8 +46,10 @@ API to add a new FPGA region
 ----------------------------
 
 * struct fpga_region - The FPGA region struct
-* devm_fpga_region_create() - Allocate and init a region struct
-* fpga_region_register() -  Register an FPGA region
+* fpga_region_register_full() -  Create and register an FPGA region using the
+  fpga_region_info structure to provide the full flexibility of options
+* fpga_region_register() -  Create and register an FPGA region using standard
+  arguments
 * fpga_region_unregister() -  Unregister an FPGA region
 
 The FPGA region's probe function will need to get a reference to the FPGA
@@ -76,7 +78,7 @@ following APIs to handle building or tearing down that list.
    :functions: fpga_region
 
 .. kernel-doc:: drivers/fpga/fpga-region.c
-   :functions: devm_fpga_region_create
+   :functions: fpga_region_register_full
 
 .. kernel-doc:: drivers/fpga/fpga-region.c
    :functions: fpga_region_register
diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
index 1eeb42af1012..4aebde0a7f1c 100644
--- a/drivers/fpga/dfl-fme-region.c
+++ b/drivers/fpga/dfl-fme-region.c
@@ -30,6 +30,7 @@ static int fme_region_get_bridges(struct fpga_region *region)
 static int fme_region_probe(struct platform_device *pdev)
 {
 	struct dfl_fme_region_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct fpga_region_info info = { 0 };
 	struct device *dev = &pdev->dev;
 	struct fpga_region *region;
 	struct fpga_manager *mgr;
@@ -39,20 +40,18 @@ static int fme_region_probe(struct platform_device *pdev)
 	if (IS_ERR(mgr))
 		return -EPROBE_DEFER;
 
-	region = devm_fpga_region_create(dev, mgr, fme_region_get_bridges);
-	if (!region) {
-		ret = -ENOMEM;
+	info.mgr = mgr;
+	info.compat_id = mgr->compat_id;
+	info.get_bridges = fme_region_get_bridges;
+	info.priv = pdata;
+	region = fpga_region_register_full(dev, &info);
+	if (IS_ERR(region)) {
+		ret = PTR_ERR(region);
 		goto eprobe_mgr_put;
 	}
 
-	region->priv = pdata;
-	region->compat_id = mgr->compat_id;
 	platform_set_drvdata(pdev, region);
 
-	ret = fpga_region_register(region);
-	if (ret)
-		goto eprobe_mgr_put;
-
 	dev_dbg(dev, "DFL FME FPGA Region probed\n");
 
 	return 0;
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 511b20ff35a3..3905995ef6d5 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -1400,19 +1400,15 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
 	if (!cdev)
 		return ERR_PTR(-ENOMEM);
 
-	cdev->region = devm_fpga_region_create(info->dev, NULL, NULL);
-	if (!cdev->region) {
-		ret = -ENOMEM;
-		goto free_cdev_exit;
-	}
-
 	cdev->parent = info->dev;
 	mutex_init(&cdev->lock);
 	INIT_LIST_HEAD(&cdev->port_dev_list);
 
-	ret = fpga_region_register(cdev->region);
-	if (ret)
+	cdev->region = fpga_region_register(info->dev, NULL, NULL);
+	if (IS_ERR(cdev->region)) {
+		ret = PTR_ERR(cdev->region);
 		goto free_cdev_exit;
+	}
 
 	/* create and init build info for enumeration */
 	binfo = devm_kzalloc(info->dev, sizeof(*binfo), GFP_KERNEL);
diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
index a4838715221f..8af108a383e0 100644
--- a/drivers/fpga/fpga-region.c
+++ b/drivers/fpga/fpga-region.c
@@ -180,39 +180,42 @@ static struct attribute *fpga_region_attrs[] = {
 ATTRIBUTE_GROUPS(fpga_region);
 
 /**
- * fpga_region_create - alloc and init a struct fpga_region
+ * fpga_region_register_full - create and register an FPGA Region device
  * @parent: device parent
- * @mgr: manager that programs this region
- * @get_bridges: optional function to get bridges to a list
- *
- * The caller of this function is responsible for freeing the resulting region
- * struct with fpga_region_free().  Using devm_fpga_region_create() instead is
- * recommended.
+ * @info: parameters for FPGA Region
  *
- * Return: struct fpga_region or NULL
+ * Return: struct fpga_region or ERR_PTR()
  */
-struct fpga_region
-*fpga_region_create(struct device *parent,
-		    struct fpga_manager *mgr,
-		    int (*get_bridges)(struct fpga_region *))
+struct fpga_region *
+fpga_region_register_full(struct device *parent, const struct fpga_region_info *info)
 {
 	struct fpga_region *region;
 	int id, ret = 0;
 
+	if (!info) {
+		dev_err(parent,
+			"Attempt to register without required info structure\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	region = kzalloc(sizeof(*region), GFP_KERNEL);
 	if (!region)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	id = ida_simple_get(&fpga_region_ida, 0, 0, GFP_KERNEL);
-	if (id < 0)
+	if (id < 0) {
+		ret = id;
 		goto err_free;
+	}
+
+	region->mgr = info->mgr;
+	region->compat_id = info->compat_id;
+	region->priv = info->priv;
+	region->get_bridges = info->get_bridges;
 
-	region->mgr = mgr;
-	region->get_bridges = get_bridges;
 	mutex_init(&region->mutex);
 	INIT_LIST_HEAD(&region->bridge_list);
 
-	device_initialize(&region->dev);
 	region->dev.class = fpga_region_class;
 	region->dev.parent = parent;
 	region->dev.of_node = parent->of_node;
@@ -222,6 +225,12 @@ struct fpga_region
 	if (ret)
 		goto err_remove;
 
+	ret = device_register(&region->dev);
+	if (ret) {
+		put_device(&region->dev);
+		return ERR_PTR(ret);
+	}
+
 	return region;
 
 err_remove:
@@ -229,76 +238,32 @@ struct fpga_region
 err_free:
 	kfree(region);
 
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(fpga_region_create);
-
-/**
- * fpga_region_free - free an FPGA region created by fpga_region_create()
- * @region: FPGA region
- */
-void fpga_region_free(struct fpga_region *region)
-{
-	ida_simple_remove(&fpga_region_ida, region->dev.id);
-	kfree(region);
-}
-EXPORT_SYMBOL_GPL(fpga_region_free);
-
-static void devm_fpga_region_release(struct device *dev, void *res)
-{
-	struct fpga_region *region = *(struct fpga_region **)res;
-
-	fpga_region_free(region);
+	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL_GPL(fpga_region_register_full);
 
 /**
- * devm_fpga_region_create - create and initialize a managed FPGA region struct
+ * fpga_region_register - create and register an FPGA Region device
  * @parent: device parent
  * @mgr: manager that programs this region
  * @get_bridges: optional function to get bridges to a list
  *
- * This function is intended for use in an FPGA region driver's probe function.
- * After the region driver creates the region struct with
- * devm_fpga_region_create(), it should register it with fpga_region_register().
- * The region driver's remove function should call fpga_region_unregister().
- * The region struct allocated with this function will be freed automatically on
- * driver detach.  This includes the case of a probe function returning error
- * before calling fpga_region_register(), the struct will still get cleaned up.
+ * This simple version of the register should be sufficient for most users.
+ * The fpga_region_register_full() function is available for users that need to
+ * pass additional, optional parameters.
  *
- * Return: struct fpga_region or NULL
+ * Return: struct fpga_region or ERR_PTR()
  */
-struct fpga_region
-*devm_fpga_region_create(struct device *parent,
-			 struct fpga_manager *mgr,
-			 int (*get_bridges)(struct fpga_region *))
+struct fpga_region *
+fpga_region_register(struct device *parent, struct fpga_manager *mgr,
+		     int (*get_bridges)(struct fpga_region *))
 {
-	struct fpga_region **ptr, *region;
-
-	ptr = devres_alloc(devm_fpga_region_release, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
-		return NULL;
+	struct fpga_region_info info = { 0 };
 
-	region = fpga_region_create(parent, mgr, get_bridges);
-	if (!region) {
-		devres_free(ptr);
-	} else {
-		*ptr = region;
-		devres_add(parent, ptr);
-	}
+	info.mgr = mgr;
+	info.get_bridges = get_bridges;
 
-	return region;
-}
-EXPORT_SYMBOL_GPL(devm_fpga_region_create);
-
-/**
- * fpga_region_register - register an FPGA region
- * @region: FPGA region
- *
- * Return: 0 or -errno
- */
-int fpga_region_register(struct fpga_region *region)
-{
-	return device_add(&region->dev);
+	return fpga_region_register_full(parent, &info);
 }
 EXPORT_SYMBOL_GPL(fpga_region_register);
 
@@ -316,6 +281,10 @@ EXPORT_SYMBOL_GPL(fpga_region_unregister);
 
 static void fpga_region_dev_release(struct device *dev)
 {
+	struct fpga_region *region = to_fpga_region(dev);
+
+	ida_simple_remove(&fpga_region_ida, region->dev.id);
+	kfree(region);
 }
 
 /**
diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
index e3c25576b6b9..9c662db1c508 100644
--- a/drivers/fpga/of-fpga-region.c
+++ b/drivers/fpga/of-fpga-region.c
@@ -405,16 +405,12 @@ static int of_fpga_region_probe(struct platform_device *pdev)
 	if (IS_ERR(mgr))
 		return -EPROBE_DEFER;
 
-	region = devm_fpga_region_create(dev, mgr, of_fpga_region_get_bridges);
-	if (!region) {
-		ret = -ENOMEM;
+	region = fpga_region_register(dev, mgr, of_fpga_region_get_bridges);
+	if (IS_ERR(region)) {
+		ret = PTR_ERR(region);
 		goto eprobe_mgr_put;
 	}
 
-	ret = fpga_region_register(region);
-	if (ret)
-		goto eprobe_mgr_put;
-
 	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
 	platform_set_drvdata(pdev, region);
 
diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-region.h
index 27cb706275db..ae111beeffba 100644
--- a/include/linux/fpga/fpga-region.h
+++ b/include/linux/fpga/fpga-region.h
@@ -7,6 +7,27 @@
 #include <linux/fpga/fpga-mgr.h>
 #include <linux/fpga/fpga-bridge.h>
 
+struct fpga_region;
+
+/**
+ * struct fpga_region_info - collection of parameters an FPGA Region
+ * @mgr: fpga region manager
+ * @compat_id: FPGA region id for compatibility check.
+ * @priv: fpga region private data
+ * @get_bridges: optional function to get bridges to a list
+ *
+ * fpga_region_info contains parameters for the register function. These
+ * are separated into an info structure because they some are optional
+ * others could be added to in the future. The info structure facilitates
+ * maintaining a stable API.
+ */
+struct fpga_region_info {
+	struct fpga_manager *mgr;
+	struct fpga_compat_id *compat_id;
+	void *priv;
+	int (*get_bridges)(struct fpga_region *region);
+};
+
 /**
  * struct fpga_region - FPGA Region structure
  * @dev: FPGA Region device
@@ -37,15 +58,12 @@ struct fpga_region *fpga_region_class_find(
 
 int fpga_region_program_fpga(struct fpga_region *region);
 
-struct fpga_region
-*fpga_region_create(struct device *dev, struct fpga_manager *mgr,
-		    int (*get_bridges)(struct fpga_region *));
-void fpga_region_free(struct fpga_region *region);
-int fpga_region_register(struct fpga_region *region);
-void fpga_region_unregister(struct fpga_region *region);
+struct fpga_region *
+fpga_region_register_full(struct device *parent, const struct fpga_region_info *info);
 
-struct fpga_region
-*devm_fpga_region_create(struct device *dev, struct fpga_manager *mgr,
-			int (*get_bridges)(struct fpga_region *));
+struct fpga_region *
+fpga_region_register(struct device *parent, struct fpga_manager *mgr,
+		     int (*get_bridges)(struct fpga_region *));
+void fpga_region_unregister(struct fpga_region *region);
 
 #endif /* _FPGA_REGION_H */
-- 
2.25.1