Message-Id: <1531172389-7312-1-git-send-email-atull@kernel.org>
Date:   Mon,  9 Jul 2018 16:39:49 -0500
From:   Alan Tull <atull@...nel.org>
To:     Moritz Fischer <mdf@...nel.org>
Cc:     Alan Tull <atull@...nel.org>,
        Appana Durga Kedareswara rao <appana.durga.rao@...inx.com>,
        linux-kernel@...r.kernel.org, linux-fpga@...r.kernel.org
Subject: [PATCH] fpga: mgr: rework fpga_mgr_get API for multiple managers

Change fpga_mgr_get() function to take manager as the parameter
instead of dev.  Caller probably has a pointer to manager already
anyway, so remove code that searched for manager based on dev.  The
rationale for this change is that cards that have more than one FPGA
may have more than one manager.

Add new __fpga_mgr_create() API which adds an 'owner' parameter.  This
API will save owner in struct fpga_manager.

Existing fpga_mgr_create() API becomes a macro that calls
__fpga_mgr_create(), setting owner to THIS_MODULE of caller.

fpga_mgr_get() will do try_module_get(mgr->owner).  For drivers that
have one manager, this has the same effect as the code it replaces
that did try_module_get(dev->parent->driver->owner) since the parent
is the low level FPGA manager driver.

Fixes: 9dce0287a60d ("fpga: add method to get fpga manager from device")
Reported-by: Appana Durga Kedareswara rao <appana.durga.rao@...inx.com>
Signed-off-by: Alan Tull <atull@...nel.org>
---
 drivers/fpga/fpga-mgr.c       | 77 +++++++++++++++++++------------------------
 include/linux/fpga/fpga-mgr.h | 15 +++++----
 2 files changed, 43 insertions(+), 49 deletions(-)

diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index c1564cf..8d0ac96 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -162,9 +162,7 @@ static int fpga_mgr_write_complete(struct fpga_manager *mgr,
  *
  * Step the low level fpga manager through the device-specific steps of getting
  * an FPGA ready to be configured, writing the image to it, then doing whatever
- * post-configuration steps necessary.  This code assumes the caller got the
- * mgr pointer from of_fpga_mgr_get() or fpga_mgr_get() and checked that it is
- * not an error code.
+ * post-configuration steps necessary.
  *
  * This is the preferred entry point for FPGA programming, it does not require
  * any contiguous kernel memory.
@@ -239,8 +237,7 @@ static int fpga_mgr_buf_load_mapped(struct fpga_manager *mgr,
  *
  * Step the low level fpga manager through the device-specific steps of getting
  * an FPGA ready to be configured, writing the image to it, then doing whatever
- * post-configuration steps necessary.  This code assumes the caller got the
- * mgr pointer from of_fpga_mgr_get() and checked that it is not an error code.
+ * post-configuration steps necessary.
  *
  * Return: 0 on success, negative error code otherwise.
  */
@@ -310,9 +307,7 @@ static int fpga_mgr_buf_load(struct fpga_manager *mgr,
  *
  * Request an FPGA image using the firmware class, then write out to the FPGA.
  * Update the state before each step to provide info on what step failed if
- * there is a failure.  This code assumes the caller got the mgr pointer
- * from of_fpga_mgr_get() or fpga_mgr_get() and checked that it is not an error
- * code.
+ * there is a failure.
  *
  * Return: 0 on success, negative error code otherwise.
  */
@@ -347,8 +342,11 @@ static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
  * @mgr:	fpga manager
  * @info:	fpga image information.
  *
- * Load the FPGA from an image which is indicated in @info.  If successful, the
- * FPGA ends up in operating mode.
+ * Load the FPGA from an image which is indicated in @info.  @mgr is a
+ * valid pointer to an FPGA manager whose refcount has been
+ * incremented by of_fpga_mgr_get() or fpga_mgr_get() and has been
+ * locked by fpga_mgr_lock().  If successful, the FPGA ends up in
+ * operating mode.
  *
  * Return: 0 on success, negative error code otherwise.
  */
@@ -416,41 +414,28 @@ static struct attribute *fpga_mgr_attrs[] = {
 };
 ATTRIBUTE_GROUPS(fpga_mgr);
 
-static struct fpga_manager *__fpga_mgr_get(struct device *dev)
+/* Assumes mgr->dev has refcount incremented already. */
+static struct fpga_manager *__fpga_mgr_get(struct fpga_manager *mgr)
 {
-	struct fpga_manager *mgr;
-
-	mgr = to_fpga_manager(dev);
-
-	if (!try_module_get(dev->parent->driver->owner))
-		goto err_dev;
+	if (try_module_get(mgr->owner))
+		return mgr;
 
-	return mgr;
+	put_device(&mgr->dev);
 
-err_dev:
-	put_device(dev);
 	return ERR_PTR(-ENODEV);
 }
 
-static int fpga_mgr_dev_match(struct device *dev, const void *data)
-{
-	return dev->parent == data;
-}
-
 /**
- * fpga_mgr_get - Given a device, get a reference to a fpga mgr.
- * @dev:	parent device that fpga mgr was registered with
+ * fpga_mgr_get - Increment refcount for a fpga mgr.
+ * @mgr:	fpga manager
  *
  * Return: fpga manager struct or IS_ERR() condition containing error code.
  */
-struct fpga_manager *fpga_mgr_get(struct device *dev)
+struct fpga_manager *fpga_mgr_get(struct fpga_manager *mgr)
 {
-	struct device *mgr_dev = class_find_device(fpga_mgr_class, NULL, dev,
-						   fpga_mgr_dev_match);
-	if (!mgr_dev)
-		return ERR_PTR(-ENODEV);
+	get_device(&mgr->dev);
 
-	return __fpga_mgr_get(mgr_dev);
+	return __fpga_mgr_get(mgr);
 }
 EXPORT_SYMBOL_GPL(fpga_mgr_get);
 
@@ -468,6 +453,7 @@ static int fpga_mgr_of_node_match(struct device *dev, const void *data)
  */
 struct fpga_manager *of_fpga_mgr_get(struct device_node *node)
 {
+	struct fpga_manager *mgr;
 	struct device *dev;
 
 	dev = class_find_device(fpga_mgr_class, NULL, node,
@@ -475,7 +461,9 @@ struct fpga_manager *of_fpga_mgr_get(struct device_node *node)
 	if (!dev)
 		return ERR_PTR(-ENODEV);
 
-	return __fpga_mgr_get(dev);
+	mgr = to_fpga_manager(dev);
+
+	return __fpga_mgr_get(mgr);
 }
 EXPORT_SYMBOL_GPL(of_fpga_mgr_get);
 
@@ -485,7 +473,7 @@ EXPORT_SYMBOL_GPL(of_fpga_mgr_get);
  */
 void fpga_mgr_put(struct fpga_manager *mgr)
 {
-	module_put(mgr->dev.parent->driver->owner);
+	module_put(mgr->owner);
 	put_device(&mgr->dev);
 }
 EXPORT_SYMBOL_GPL(fpga_mgr_put);
@@ -494,9 +482,8 @@ EXPORT_SYMBOL_GPL(fpga_mgr_put);
  * fpga_mgr_lock - Lock FPGA manager for exclusive use
  * @mgr:	fpga manager
  *
- * Given a pointer to FPGA Manager (from fpga_mgr_get() or
- * of_fpga_mgr_put()) attempt to get the mutex. The user should call
- * fpga_mgr_lock() and verify that it returns 0 before attempting to
+ * Given a pointer to FPGA Manager, attempt to get the mutex. The user should
+ * call fpga_mgr_lock() and verify that it returns 0 before attempting to
  * program the FPGA.  Likewise, the user should call fpga_mgr_unlock
  * when done programming the FPGA.
  *
@@ -524,17 +511,20 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
 EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
 
 /**
- * fpga_mgr_create - create and initialize a FPGA manager struct
+ * __fpga_mgr_create - create and initialize a FPGA manager struct
  * @dev:	fpga manager device from pdev
+ * @owner:	owner of manager, i.e. THIS_MODULE of manager driver
  * @name:	fpga manager name
  * @mops:	pointer to structure of fpga manager ops
  * @priv:	fpga manager private data
  *
  * Return: pointer to struct fpga_manager or NULL
  */
-struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
-				     const struct fpga_manager_ops *mops,
-				     void *priv)
+struct fpga_manager *__fpga_mgr_create(struct device *dev,
+				       struct module *owner,
+				       const char *name,
+				       const struct fpga_manager_ops *mops,
+				       void *priv)
 {
 	struct fpga_manager *mgr;
 	int id, ret;
@@ -563,6 +553,7 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
 
 	mutex_init(&mgr->ref_mutex);
 
+	mgr->owner = owner;
 	mgr->name = name;
 	mgr->mops = mops;
 	mgr->priv = priv;
@@ -587,7 +578,7 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
 
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(fpga_mgr_create);
+EXPORT_SYMBOL_GPL(__fpga_mgr_create);
 
 /**
  * fpga_mgr_free - deallocate a FPGA manager
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index eec7c24..f948202 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -127,6 +127,7 @@ struct fpga_manager_ops {
 /**
  * struct fpga_manager - fpga manager structure
  * @name: name of low level fpga manager
+ * @owner: module that owns this manager
  * @dev: fpga manager device
  * @ref_mutex: only allows one reference to fpga manager
  * @state: state of fpga manager
@@ -135,6 +136,7 @@ struct fpga_manager_ops {
  */
 struct fpga_manager {
 	const char *name;
+	struct module *owner;
 	struct device dev;
 	struct mutex ref_mutex;
 	enum fpga_mgr_states state;
@@ -154,14 +156,15 @@ int fpga_mgr_lock(struct fpga_manager *mgr);
 void fpga_mgr_unlock(struct fpga_manager *mgr);
 
 struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
-
-struct fpga_manager *fpga_mgr_get(struct device *dev);
-
+struct fpga_manager *fpga_mgr_get(struct fpga_manager *mgr);
 void fpga_mgr_put(struct fpga_manager *mgr);
 
-struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
-				     const struct fpga_manager_ops *mops,
-				     void *priv);
+struct fpga_manager *__fpga_mgr_create(struct device *dev,
+				       struct module *owner, const char *name,
+				       const struct fpga_manager_ops *mops,
+				       void *priv);
+#define fpga_mgr_create(dev, name, mops, priv)	\
+	__fpga_mgr_create((dev), THIS_MODULE, (name), (mops), (priv))
 void fpga_mgr_free(struct fpga_manager *mgr);
 int fpga_mgr_register(struct fpga_manager *mgr);
 void fpga_mgr_unregister(struct fpga_manager *mgr);
-- 
2.7.4

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