Message-Id: <20190313041524.14644-6-alastair@au1.ibm.com>
Date:   Wed, 13 Mar 2019 15:15:20 +1100
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     "Alastair D'Silva" <alastair@...ilva.org>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 5/7] ocxl: Create a clear delineation between ocxl backend & frontend

From: Alastair D'Silva <alastair@...ilva.org>

The OCXL driver contains both frontend code for interacting with userspace,
as well as backend code for interacting with the hardware.

This patch separates the backend code from the frontend so that it can be
used by other device drivers that communicate via OpenCAPI.

Relocate dev, cdev & sysfs files to the frontend code to allow external
drivers to maintain their own devices.

Reference counting on the device in the backend is replaced with kref
counting.

Move file & sysfs layer initialisation from core.c (backend) to
pci.c (frontend).

Create an ocxl_function oriented interface for initing devices &
enumerating AFUs.

Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
 drivers/misc/ocxl/context.c       |   2 +-
 drivers/misc/ocxl/core.c          | 205 +++++++++++++++++++-----------
 drivers/misc/ocxl/file.c          | 122 +++++++++++-------
 drivers/misc/ocxl/ocxl_internal.h |  39 +++---
 drivers/misc/ocxl/pci.c           |  61 ++++-----
 drivers/misc/ocxl/sysfs.c         |  58 +++++----
 include/misc/ocxl.h               | 121 ++++++++++++++++--
 7 files changed, 411 insertions(+), 197 deletions(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 1534b56f1db1..9a37e9632cd9 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -241,7 +241,7 @@ int ocxl_context_detach(struct ocxl_context *ctx)
 	}
 	rc = ocxl_link_remove_pe(ctx->afu->fn->link, ctx->pasid);
 	if (rc) {
-		dev_warn(&ctx->afu->dev,
+		dev_warn(&dev->dev,
 			"Couldn't remove PE entry cleanly: %d\n", rc);
 	}
 	return 0;
diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
index 2fd0c700e8a0..c632ec372342 100644
--- a/drivers/misc/ocxl/core.c
+++ b/drivers/misc/ocxl/core.c
@@ -13,16 +13,6 @@ static void ocxl_fn_put(struct ocxl_fn *fn)
 	put_device(&fn->dev);
 }
 
-struct ocxl_afu *ocxl_afu_get(struct ocxl_afu *afu)
-{
-	return (get_device(&afu->dev) == NULL) ? NULL : afu;
-}
-
-void ocxl_afu_put(struct ocxl_afu *afu)
-{
-	put_device(&afu->dev);
-}
-
 static struct ocxl_afu *alloc_afu(struct ocxl_fn *fn)
 {
 	struct ocxl_afu *afu;
@@ -31,6 +21,7 @@ static struct ocxl_afu *alloc_afu(struct ocxl_fn *fn)
 	if (!afu)
 		return NULL;
 
+	kref_init(&afu->kref);
 	mutex_init(&afu->contexts_lock);
 	mutex_init(&afu->afu_control_lock);
 	idr_init(&afu->contexts_idr);
@@ -39,32 +30,26 @@ static struct ocxl_afu *alloc_afu(struct ocxl_fn *fn)
 	return afu;
 }
 
-static void free_afu(struct ocxl_afu *afu)
+static void afu_release(struct kref *kref)
 {
+	struct ocxl_afu *afu = container_of(kref, struct ocxl_afu, kref);
+
 	idr_destroy(&afu->contexts_idr);
 	ocxl_fn_put(afu->fn);
 	kfree(afu);
 }
 
-static void free_afu_dev(struct device *dev)
+void ocxl_afu_get(struct ocxl_afu *afu)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(dev);
-
-	ocxl_unregister_afu(afu);
-	free_afu(afu);
+	kref_get(&afu->kref);
 }
+EXPORT_SYMBOL_GPL(ocxl_afu_get);
 
-static int set_afu_device(struct ocxl_afu *afu, const char *location)
+void ocxl_afu_put(struct ocxl_afu *afu)
 {
-	struct ocxl_fn *fn = afu->fn;
-	int rc;
-
-	afu->dev.parent = &fn->dev;
-	afu->dev.release = free_afu_dev;
-	rc = dev_set_name(&afu->dev, "%s.%s.%hhu", afu->config.name, location,
-		afu->config.idx);
-	return rc;
+	kref_put(&afu->kref, afu_release);
 }
+EXPORT_SYMBOL_GPL(ocxl_afu_put);
 
 static int assign_afu_actag(struct ocxl_afu *afu)
 {
@@ -233,27 +218,25 @@ static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct pci_dev *dev)
 	if (rc)
 		return rc;
 
-	rc = set_afu_device(afu, dev_name(&dev->dev));
-	if (rc)
-		return rc;
-
 	rc = assign_afu_actag(afu);
 	if (rc)
 		return rc;
 
 	rc = assign_afu_pasid(afu);
-	if (rc) {
-		reclaim_afu_actag(afu);
-		return rc;
-	}
+	if (rc)
+		goto err_free_actag;
 
 	rc = map_mmio_areas(afu);
-	if (rc) {
-		reclaim_afu_pasid(afu);
-		reclaim_afu_actag(afu);
-		return rc;
-	}
+	if (rc)
+		goto err_free_pasid;
+
 	return 0;
+
+err_free_pasid:
+	reclaim_afu_pasid(afu);
+err_free_actag:
+	reclaim_afu_actag(afu);
+	return rc;
 }
 
 static void deconfigure_afu(struct ocxl_afu *afu)
@@ -265,16 +248,8 @@ static void deconfigure_afu(struct ocxl_afu *afu)
 
 static int activate_afu(struct pci_dev *dev, struct ocxl_afu *afu)
 {
-	int rc;
-
 	ocxl_config_set_afu_state(dev, afu->config.dvsec_afu_control_pos, 1);
-	/*
-	 * Char device creation is the last step, as processes can
-	 * call our driver immediately, so all our inits must be finished.
-	 */
-	rc = ocxl_create_cdev(afu);
-	if (rc)
-		return rc;
+
 	return 0;
 }
 
@@ -282,11 +257,10 @@ static void deactivate_afu(struct ocxl_afu *afu)
 {
 	struct pci_dev *dev = to_pci_dev(afu->fn->dev.parent);
 
-	ocxl_destroy_cdev(afu);
 	ocxl_config_set_afu_state(dev, afu->config.dvsec_afu_control_pos, 0);
 }
 
-int init_afu(struct pci_dev *dev, struct ocxl_fn *fn, u8 afu_idx)
+static int init_afu(struct pci_dev *dev, struct ocxl_fn *fn, u8 afu_idx)
 {
 	int rc;
 	struct ocxl_afu *afu;
@@ -297,41 +271,29 @@ int init_afu(struct pci_dev *dev, struct ocxl_fn *fn, u8 afu_idx)
 
 	rc = configure_afu(afu, afu_idx, dev);
 	if (rc) {
-		free_afu(afu);
+		ocxl_afu_put(afu);
 		return rc;
 	}
 
-	rc = ocxl_register_afu(afu);
-	if (rc)
-		goto err;
-
-	rc = ocxl_sysfs_add_afu(afu);
-	if (rc)
-		goto err;
-
 	rc = activate_afu(dev, afu);
-	if (rc)
-		goto err_sys;
+	if (rc) {
+		deconfigure_afu(afu);
+		ocxl_afu_put(afu);
+		return rc;
+	}
 
 	list_add_tail(&afu->list, &fn->afu_list);
-	return 0;
 
-err_sys:
-	ocxl_sysfs_remove_afu(afu);
-err:
-	deconfigure_afu(afu);
-	device_unregister(&afu->dev);
-	return rc;
+	return 0;
 }
 
-void remove_afu(struct ocxl_afu *afu)
+static void remove_afu(struct ocxl_afu *afu)
 {
 	list_del(&afu->list);
 	ocxl_context_detach_all(afu);
 	deactivate_afu(afu);
-	ocxl_sysfs_remove_afu(afu);
 	deconfigure_afu(afu);
-	device_unregister(&afu->dev);
+	ocxl_afu_put(afu); // matches the implicit get in alloc_afu
 }
 
 static struct ocxl_fn *alloc_function(void)
@@ -358,7 +320,7 @@ static void free_function(struct ocxl_fn *fn)
 
 static void free_function_dev(struct device *dev)
 {
-	struct ocxl_fn *fn = to_ocxl_function(dev);
+	struct ocxl_fn *fn = container_of(dev, struct ocxl_fn, dev);
 
 	free_function(fn);
 }
@@ -372,7 +334,6 @@ static int set_function_device(struct ocxl_fn *fn, struct pci_dev *dev)
 	rc = dev_set_name(&fn->dev, "ocxlfn.%s", dev_name(&dev->dev));
 	if (rc)
 		return rc;
-	pci_set_drvdata(dev, fn);
 	return 0;
 }
 
@@ -490,7 +451,7 @@ static void deconfigure_function(struct ocxl_fn *fn)
 	pci_disable_device(dev);
 }
 
-struct ocxl_fn *init_function(struct pci_dev *dev)
+static struct ocxl_fn *init_function(struct pci_dev *dev)
 {
 	struct ocxl_fn *fn;
 	int rc;
@@ -514,8 +475,104 @@ struct ocxl_fn *init_function(struct pci_dev *dev)
 	return fn;
 }
 
-void remove_function(struct ocxl_fn *fn)
+// Device detection & initialisation
+
+struct ocxl_fn *ocxl_function_open(struct pci_dev *dev)
+{
+	int rc, afu_count = 0;
+	u8 afu;
+	struct ocxl_fn *fn;
+
+	if (!radix_enabled()) {
+		dev_err(&dev->dev, "Unsupported memory model (hash)\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	fn = init_function(dev);
+	if (IS_ERR(fn)) {
+		dev_err(&dev->dev, "function init failed: %li\n",
+			PTR_ERR(fn));
+		return fn;
+	}
+
+	for (afu = 0; afu <= fn->config.max_afu_index; afu++) {
+		rc = ocxl_config_check_afu_index(dev, &fn->config, afu);
+		if (rc > 0) {
+			rc = init_afu(dev, fn, afu);
+			if (rc) {
+				dev_err(&dev->dev,
+					"Can't initialize AFU index %d\n", afu);
+				continue;
+			}
+			afu_count++;
+		}
+	}
+	dev_info(&dev->dev, "%d AFU(s) configured\n", afu_count);
+	return fn;
+}
+EXPORT_SYMBOL_GPL(ocxl_function_open);
+
+struct list_head *ocxl_function_afu_list(struct ocxl_fn *fn)
+{
+	return &fn->afu_list;
+}
+EXPORT_SYMBOL_GPL(ocxl_function_afu_list);
+
+struct ocxl_afu *ocxl_function_fetch_afu(struct ocxl_fn *fn, u8 afu_idx)
+{
+	struct ocxl_afu *afu;
+
+	list_for_each_entry(afu, &fn->afu_list, list) {
+		if (afu->config.idx == afu_idx)
+			return afu;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ocxl_function_fetch_afu);
+
+const struct ocxl_fn_config *ocxl_function_config(struct ocxl_fn *fn)
 {
+	return &fn->config;
+}
+EXPORT_SYMBOL_GPL(ocxl_function_config);
+
+void ocxl_function_close(struct ocxl_fn *fn)
+{
+	struct ocxl_afu *afu, *tmp;
+
+	list_for_each_entry_safe(afu, tmp, &fn->afu_list, list) {
+		if (afu->private && afu->private_release)
+			afu->private_release(afu->private);
+		remove_afu(afu);
+	}
+
 	deconfigure_function(fn);
 	device_unregister(&fn->dev);
 }
+EXPORT_SYMBOL_GPL(ocxl_function_close);
+
+// AFU Metadata
+
+struct ocxl_afu_config *ocxl_afu_config(struct ocxl_afu *afu)
+{
+	return &afu->config;
+}
+EXPORT_SYMBOL_GPL(ocxl_afu_config);
+
+void ocxl_afu_set_private(struct ocxl_afu *afu, void *private,
+			void (*private_release)(void *private))
+{
+	afu->private = private;
+	afu->private_release = private_release;
+}
+EXPORT_SYMBOL_GPL(ocxl_afu_set_private);
+
+void *ocxl_afu_get_private(struct ocxl_afu *afu)
+{
+	if (afu)
+		return afu->private;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ocxl_afu_get_private);
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 865b3d176431..424bb0b40afb 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -17,12 +17,10 @@ static struct class *ocxl_class;
 static struct mutex minors_idr_lock;
 static struct idr minors_idr;
 
-static struct ocxl_afu *find_and_get_afu(dev_t devno)
+static struct ocxl_file_info *find_file_info(dev_t devno)
 {
-	struct ocxl_afu *afu;
-	int afu_minor;
+	struct ocxl_file_info *info;
 
-	afu_minor = MINOR(devno);
 	/*
 	 * We don't declare an RCU critical section here, as our AFU
 	 * is protected by a reference counter on the device. By the time the
@@ -30,56 +28,52 @@ static struct ocxl_afu *find_and_get_afu(dev_t devno)
 	 * the device is already at 0, so no user API will access that AFU and
 	 * this function can't return it.
 	 */
-	afu = idr_find(&minors_idr, afu_minor);
-	if (afu)
-		ocxl_afu_get(afu);
-	return afu;
+	info = idr_find(&minors_idr, MINOR(devno));
+	return info;
 }
 
-static int allocate_afu_minor(struct ocxl_afu *afu)
+static int allocate_minor(struct ocxl_file_info *info)
 {
 	int minor;
 
 	mutex_lock(&minors_idr_lock);
-	minor = idr_alloc(&minors_idr, afu, 0, OCXL_NUM_MINORS, GFP_KERNEL);
+	minor = idr_alloc(&minors_idr, info, 0, OCXL_NUM_MINORS, GFP_KERNEL);
 	mutex_unlock(&minors_idr_lock);
 	return minor;
 }
 
-static void free_afu_minor(struct ocxl_afu *afu)
+static void free_minor(struct ocxl_file_info *info)
 {
 	mutex_lock(&minors_idr_lock);
-	idr_remove(&minors_idr, MINOR(afu->dev.devt));
+	idr_remove(&minors_idr, MINOR(info->dev.devt));
 	mutex_unlock(&minors_idr_lock);
 }
 
 static int afu_open(struct inode *inode, struct file *file)
 {
-	struct ocxl_afu *afu;
+	struct ocxl_file_info *info;
 	struct ocxl_context *ctx;
 	int rc;
 
 	pr_debug("%s for device %x\n", __func__, inode->i_rdev);
 
-	afu = find_and_get_afu(inode->i_rdev);
-	if (!afu)
+	info = find_file_info(inode->i_rdev);
+	if (!info)
 		return -ENODEV;
 
 	ctx = ocxl_context_alloc();
 	if (!ctx) {
 		rc = -ENOMEM;
-		goto put_afu;
+		goto err;
 	}
 
-	rc = ocxl_context_init(ctx, afu, inode->i_mapping);
+	rc = ocxl_context_init(ctx, info->afu, inode->i_mapping);
 	if (rc)
-		goto put_afu;
+		goto err;
 	file->private_data = ctx;
-	ocxl_afu_put(afu);
 	return 0;
 
-put_afu:
-	ocxl_afu_put(afu);
+err:
 	return rc;
 }
 
@@ -205,11 +199,16 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 	struct ocxl_ioctl_irq_fd irq_fd;
 	u64 irq_offset;
 	long rc;
+	bool closed;
 
 	pr_debug("%s for context %d, command %s\n", __func__, ctx->pasid,
 		CMD_STR(cmd));
 
-	if (ctx->status == CLOSED)
+	mutex_lock(&ctx->status_mutex);
+	closed = (ctx->status == CLOSED);
+	mutex_unlock(&ctx->status_mutex);
+
+	if (closed)
 		return -EIO;
 
 	switch (cmd) {
@@ -469,39 +468,76 @@ static const struct file_operations ocxl_afu_fops = {
 	.release        = afu_release,
 };
 
-int ocxl_create_cdev(struct ocxl_afu *afu)
+// Called when there are no more consumers of the AFU
+static void ocxl_file_release(void *private)
 {
-	int rc;
+	struct ocxl_file_info *info = private;
 
-	cdev_init(&afu->cdev, &ocxl_afu_fops);
-	rc = cdev_add(&afu->cdev, afu->dev.devt, 1);
-	if (rc) {
-		dev_err(&afu->dev, "Unable to add afu char device: %d\n", rc);
-		return rc;
-	}
-	return 0;
-}
+	ocxl_sysfs_unregister_afu(info->afu);
+	device_unregister(&info->dev);
 
-void ocxl_destroy_cdev(struct ocxl_afu *afu)
-{
-	cdev_del(&afu->cdev);
+	free_minor(info);
+	kfree(info);
 }
 
-int ocxl_register_afu(struct ocxl_afu *afu)
+int ocxl_file_register_afu(struct ocxl_afu *afu)
 {
 	int minor;
+	int rc;
+	struct ocxl_file_info *info;
+	struct ocxl_fn *fn = afu->fn;
+	struct pci_dev *pci_dev = to_pci_dev(fn->dev.parent);
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (info == NULL)
+		return -ENOMEM;
 
-	minor = allocate_afu_minor(afu);
-	if (minor < 0)
+	info->afu = afu;
+
+	minor = allocate_minor(info);
+	if (minor < 0) {
+		kfree(info);
 		return minor;
-	afu->dev.devt = MKDEV(MAJOR(ocxl_dev), minor);
-	afu->dev.class = ocxl_class;
-	return device_register(&afu->dev);
+	}
+
+	info->dev.parent = &fn->dev;
+	info->dev.devt = MKDEV(MAJOR(ocxl_dev), minor);
+	info->dev.class = ocxl_class;
+
+	ocxl_afu_set_private(afu, info, ocxl_file_release);
+
+	rc = dev_set_name(&info->dev, "%s.%s.%hhu",
+		afu->config.name, dev_name(&pci_dev->dev), afu->config.idx);
+	if (rc)
+		return rc;
+
+	rc = device_register(&info->dev);
+	if (rc)
+		return rc;
+
+	return ocxl_sysfs_register_afu(afu);
+}
+
+int ocxl_file_make_visible(struct ocxl_afu *afu)
+{
+	int rc;
+	struct ocxl_file_info *info = ocxl_afu_get_private(afu);
+
+	cdev_init(&info->cdev, &ocxl_afu_fops);
+	rc = cdev_add(&info->cdev, info->dev.devt, 1);
+	if (rc) {
+		dev_err(&info->dev, "Unable to add afu char device: %d\n", rc);
+		return rc;
+	}
+
+	return 0;
 }
 
-void ocxl_unregister_afu(struct ocxl_afu *afu)
+void ocxl_file_make_invisible(struct ocxl_afu *afu)
 {
-	free_afu_minor(afu);
+	struct ocxl_file_info *info = ocxl_afu_get_private(afu);
+
+	cdev_del(&info->cdev);
 }
 
 static char *ocxl_devnode(struct device *dev, umode_t *mode)
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 1319406ce5c6..4fc7e9597ede 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -11,9 +11,6 @@
 #define MAX_IRQ_PER_LINK	2000
 #define MAX_IRQ_PER_CONTEXT	MAX_IRQ_PER_LINK
 
-#define to_ocxl_function(d) container_of(d, struct ocxl_fn, dev)
-#define to_ocxl_afu(d) container_of(d, struct ocxl_afu, dev)
-
 extern struct pci_driver ocxl_pci_driver;
 
 struct ocxl_fn {
@@ -30,11 +27,17 @@ struct ocxl_fn {
 	void *link;
 };
 
+struct ocxl_file_info {
+	struct ocxl_afu *afu;
+	struct device dev;
+	struct cdev cdev;
+	struct bin_attribute attr_global_mmio;
+};
+
 struct ocxl_afu {
+	struct kref kref;
 	struct ocxl_fn *fn;
 	struct list_head list;
-	struct device dev;
-	struct cdev cdev;
 	struct ocxl_afu_config config;
 	int pasid_base;
 	int pasid_count; /* opened contexts */
@@ -48,7 +51,9 @@ struct ocxl_afu {
 	u64 irq_base_offset;
 	void __iomem *global_mmio_ptr;
 	u64 pp_mmio_start;
-	struct bin_attribute attr_global_mmio;
+	void *private;
+	void (*private_release)(void *private);
+
 };
 
 enum ocxl_context_status {
@@ -91,13 +96,11 @@ struct ocxl_process_element {
 	__be32 software_state;
 };
 
-struct ocxl_afu *ocxl_afu_get(struct ocxl_afu *afu);
-void ocxl_afu_put(struct ocxl_afu *afu);
-
 int ocxl_create_cdev(struct ocxl_afu *afu);
 void ocxl_destroy_cdev(struct ocxl_afu *afu);
-int ocxl_register_afu(struct ocxl_afu *afu);
-void ocxl_unregister_afu(struct ocxl_afu *afu);
+int ocxl_file_register_afu(struct ocxl_afu *afu);
+int ocxl_file_make_visible(struct ocxl_afu *afu);
+void ocxl_file_make_invisible(struct ocxl_afu *afu);
 
 int ocxl_file_init(void);
 void ocxl_file_exit(void);
@@ -134,8 +137,8 @@ int ocxl_context_mmap(struct ocxl_context *ctx,
 			struct vm_area_struct *vma);
 void ocxl_context_detach_all(struct ocxl_afu *afu);
 
-int ocxl_sysfs_add_afu(struct ocxl_afu *afu);
-void ocxl_sysfs_remove_afu(struct ocxl_afu *afu);
+int ocxl_sysfs_register_afu(struct ocxl_afu *afu);
+void ocxl_sysfs_unregister_afu(struct ocxl_afu *afu);
 
 int ocxl_afu_irq_alloc(struct ocxl_context *ctx, u64 *irq_offset);
 int ocxl_afu_irq_free(struct ocxl_context *ctx, u64 irq_offset);
@@ -144,9 +147,11 @@ int ocxl_afu_irq_set_fd(struct ocxl_context *ctx, u64 irq_offset,
 			int eventfd);
 u64 ocxl_afu_irq_get_addr(struct ocxl_context *ctx, u64 irq_offset);
 
-struct ocxl_fn *init_function(struct pci_dev *dev);
-void remove_function(struct ocxl_fn *fn);
-int init_afu(struct pci_dev *dev, struct ocxl_fn *fn, u8 afu_idx);
-void remove_afu(struct ocxl_afu *afu);
+/**
+ * Free an AFU
+ *
+ * afu: The AFU to free
+ */
+void ocxl_free_afu(struct ocxl_afu *afu);
 
 #endif /* _OCXL_INTERNAL_H_ */
diff --git a/drivers/misc/ocxl/pci.c b/drivers/misc/ocxl/pci.c
index 5926c863716c..a1ed2bb02e4b 100644
--- a/drivers/misc/ocxl/pci.c
+++ b/drivers/misc/ocxl/pci.c
@@ -16,47 +16,48 @@ MODULE_DEVICE_TABLE(pci, ocxl_pci_tbl);
 
 static int ocxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
-	int rc, afu_count = 0;
-	u8 afu;
+	int rc;
+	struct ocxl_afu *afu, *tmp;
 	struct ocxl_fn *fn;
+	struct list_head *afu_list;
 
-	if (!radix_enabled()) {
-		dev_err(&dev->dev, "Unsupported memory model (hash)\n");
-		return -ENODEV;
-	}
-
-	fn = init_function(dev);
-	if (IS_ERR(fn)) {
-		dev_err(&dev->dev, "function init failed: %li\n",
-			PTR_ERR(fn));
+	fn = ocxl_function_open(dev);
+	if (IS_ERR(fn))
 		return PTR_ERR(fn);
-	}
 
-	for (afu = 0; afu <= fn->config.max_afu_index; afu++) {
-		rc = ocxl_config_check_afu_index(dev, &fn->config, afu);
-		if (rc > 0) {
-			rc = init_afu(dev, fn, afu);
-			if (rc) {
-				dev_err(&dev->dev,
-					"Can't initialize AFU index %d\n", afu);
-				continue;
-			}
-			afu_count++;
-		}
+	pci_set_drvdata(dev, fn);
+
+	afu_list = ocxl_function_afu_list(fn);
+
+	list_for_each_entry_safe(afu, tmp, afu_list, list) {
+		rc = ocxl_file_register_afu(afu);
+		if (rc)
+			continue;
+
+		rc = ocxl_file_make_visible(afu);
+		if (rc)
+			continue;
+
+		// Defer error cleanup until the device is removed
 	}
-	dev_info(&dev->dev, "%d AFU(s) configured\n", afu_count);
+
 	return 0;
 }
 
-static void ocxl_remove(struct pci_dev *dev)
+void ocxl_remove(struct pci_dev *dev)
 {
-	struct ocxl_afu *afu, *tmp;
-	struct ocxl_fn *fn = pci_get_drvdata(dev);
+	struct ocxl_fn *fn;
+	struct ocxl_afu *afu;
+	struct list_head *afu_list;
+
+	fn = pci_get_drvdata(dev);
+	afu_list = ocxl_function_afu_list(fn);
 
-	list_for_each_entry_safe(afu, tmp, &fn->afu_list, list) {
-		remove_afu(afu);
+	list_for_each_entry(afu, afu_list, list) {
+		ocxl_file_make_invisible(afu);
 	}
-	remove_function(fn);
+
+	ocxl_function_close(fn);
 }
 
 struct pci_driver ocxl_pci_driver = {
diff --git a/drivers/misc/ocxl/sysfs.c b/drivers/misc/ocxl/sysfs.c
index 0ab1fd1b2682..a67931f1feec 100644
--- a/drivers/misc/ocxl/sysfs.c
+++ b/drivers/misc/ocxl/sysfs.c
@@ -3,11 +3,18 @@
 #include <linux/sysfs.h>
 #include "ocxl_internal.h"
 
+static inline struct ocxl_afu *to_afu(struct device *device)
+{
+	struct ocxl_file_info *info = container_of(device, struct ocxl_file_info, dev);
+
+	return info->afu;
+}
+
 static ssize_t global_mmio_size_show(struct device *device,
 				struct device_attribute *attr,
 				char *buf)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(device);
+	struct ocxl_afu *afu = to_afu(device);
 
 	return scnprintf(buf, PAGE_SIZE, "%d\n",
 			afu->config.global_mmio_size);
@@ -17,7 +24,7 @@ static ssize_t pp_mmio_size_show(struct device *device,
 				struct device_attribute *attr,
 				char *buf)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(device);
+	struct ocxl_afu *afu = to_afu(device);
 
 	return scnprintf(buf, PAGE_SIZE, "%d\n",
 			afu->config.pp_mmio_stride);
@@ -27,7 +34,7 @@ static ssize_t afu_version_show(struct device *device,
 				struct device_attribute *attr,
 				char *buf)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(device);
+	struct ocxl_afu *afu = to_afu(device);
 
 	return scnprintf(buf, PAGE_SIZE, "%hhu:%hhu\n",
 			afu->config.version_major,
@@ -38,7 +45,7 @@ static ssize_t contexts_show(struct device *device,
 		struct device_attribute *attr,
 		char *buf)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(device);
+	struct ocxl_afu *afu = to_afu(device);
 
 	return scnprintf(buf, PAGE_SIZE, "%d/%d\n",
 			afu->pasid_count, afu->pasid_max);
@@ -55,7 +62,7 @@ static ssize_t global_mmio_read(struct file *filp, struct kobject *kobj,
 				struct bin_attribute *bin_attr, char *buf,
 				loff_t off, size_t count)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(kobj_to_dev(kobj));
+	struct ocxl_afu *afu = to_afu(kobj_to_dev(kobj));
 
 	if (count == 0 || off < 0 ||
 		off >= afu->config.global_mmio_size)
@@ -86,7 +93,7 @@ static int global_mmio_mmap(struct file *filp, struct kobject *kobj,
 			struct bin_attribute *bin_attr,
 			struct vm_area_struct *vma)
 {
-	struct ocxl_afu *afu = to_ocxl_afu(kobj_to_dev(kobj));
+	struct ocxl_afu *afu = to_afu(kobj_to_dev(kobj));
 
 	if ((vma_pages(vma) + vma->vm_pgoff) >
 		(afu->config.global_mmio_size >> PAGE_SHIFT))
@@ -99,27 +106,29 @@ static int global_mmio_mmap(struct file *filp, struct kobject *kobj,
 	return 0;
 }
 
-int ocxl_sysfs_add_afu(struct ocxl_afu *afu)
+int ocxl_sysfs_register_afu(struct ocxl_afu *afu)
 {
 	int i, rc;
+	struct ocxl_file_info *info = ocxl_afu_get_private(afu);
+
+	if (!info)
+		return -EFAULT; // ocxl_file_register_afu() must be called first
 
 	for (i = 0; i < ARRAY_SIZE(afu_attrs); i++) {
-		rc = device_create_file(&afu->dev, &afu_attrs[i]);
+		rc = device_create_file(&info->dev, &afu_attrs[i]);
 		if (rc)
 			goto err;
 	}
 
-	sysfs_attr_init(&afu->attr_global_mmio.attr);
-	afu->attr_global_mmio.attr.name = "global_mmio_area";
-	afu->attr_global_mmio.attr.mode = 0600;
-	afu->attr_global_mmio.size = afu->config.global_mmio_size;
-	afu->attr_global_mmio.read = global_mmio_read;
-	afu->attr_global_mmio.mmap = global_mmio_mmap;
-	rc = device_create_bin_file(&afu->dev, &afu->attr_global_mmio);
+	sysfs_attr_init(&info->attr_global_mmio.attr);
+	info->attr_global_mmio.attr.name = "global_mmio_area";
+	info->attr_global_mmio.attr.mode = 0600;
+	info->attr_global_mmio.size = afu->config.global_mmio_size;
+	info->attr_global_mmio.read = global_mmio_read;
+	info->attr_global_mmio.mmap = global_mmio_mmap;
+	rc = device_create_bin_file(&info->dev, &info->attr_global_mmio);
 	if (rc) {
-		dev_err(&afu->dev,
-			"Unable to create global mmio attr for afu: %d\n",
-			rc);
+		dev_err(&info->dev, "Unable to create global mmio attr for afu: %d\n", rc);
 		goto err;
 	}
 
@@ -127,15 +136,20 @@ int ocxl_sysfs_add_afu(struct ocxl_afu *afu)
 
 err:
 	for (i--; i >= 0; i--)
-		device_remove_file(&afu->dev, &afu_attrs[i]);
+		device_remove_file(&info->dev, &afu_attrs[i]);
+
 	return rc;
 }
 
-void ocxl_sysfs_remove_afu(struct ocxl_afu *afu)
+void ocxl_sysfs_unregister_afu(struct ocxl_afu *afu)
 {
+	struct ocxl_file_info *info = ocxl_afu_get_private(afu);
 	int i;
 
+	if (!info)
+		return;
+
 	for (i = 0; i < ARRAY_SIZE(afu_attrs); i++)
-		device_remove_file(&afu->dev, &afu_attrs[i]);
-	device_remove_bin_file(&afu->dev, &afu->attr_global_mmio);
+		device_remove_file(&info->dev, &afu_attrs[i]);
+	device_remove_bin_file(&info->dev, &info->attr_global_mmio);
 }
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index ebbfe83cd5a6..54f8bafa3caa 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -16,11 +16,7 @@
 
 #define OCXL_AFU_NAME_SZ      (24+1)  /* add 1 for NULL termination */
 
-/*
- * The following 2 structures are a fairly generic way of representing
- * the configuration data for a function and AFU, as read from the
- * configuration space.
- */
+
 struct ocxl_afu_config {
 	u8 idx;
 	int dvsec_afu_control_pos; /* offset of AFU control DVSEC */
@@ -51,6 +47,7 @@ struct ocxl_fn_config {
 
 // These are opaque outside the ocxl driver
 struct ocxl_afu;
+struct ocxl_fn;
 struct ocxl_context;
 
 enum ocxl_endian {
@@ -59,6 +56,74 @@ enum ocxl_endian {
 	OCXL_HOST_ENDIAN = 2,   /**< AFU data is the same endianness as the host */
 };
 
+// Device detection & initialisation
+
+/**
+ * Open an OpenCAPI function on an OpenCAPI device
+ *
+ * @dev: The PCI device that contains the function
+ *
+ * Returns an opaque pointer to the function, or an error pointer (check with IS_ERR)
+ */
+struct ocxl_fn *ocxl_function_open(struct pci_dev *dev);
+
+/**
+ * Get the list of AFUs associated with a PCI function device
+ *
+ * Returns a list of struct ocxl_afu *
+ *
+ * @fn: The OpenCAPI function containing the AFUs
+ */
+struct list_head *ocxl_function_afu_list(struct ocxl_fn *fn);
+
+/**
+ * Fetch an AFU instance from an OpenCAPI function
+ *
+ * @fn: The OpenCAPI function to get the AFU from
+ * @afu_idx: The index of the AFU to get
+ *
+ * If successful, the AFU should be released with ocxl_afu_put()
+ *
+ * Returns a pointer to the AFU, or NULL on error
+ */
+struct ocxl_afu *ocxl_function_fetch_afu(struct ocxl_fn *fn, u8 afu_idx);
+
+/**
+ * Take a reference to an AFU
+ *
+ * @afu: The AFU to increment the reference count on
+ */
+void ocxl_afu_get(struct ocxl_afu *afu);
+
+/**
+ * Release a reference to an AFU
+ *
+ * @afu: The AFU to decrement the reference count on
+ */
+void ocxl_afu_put(struct ocxl_afu *afu);
+
+
+/**
+ * Get the configuration information for an OpenCAPI function
+ *
+ * @fn: The OpenCAPI function to get the config for
+ *
+ * Returns the function config, or NULL on error
+ */
+const struct ocxl_fn_config *ocxl_function_config(struct ocxl_fn *fn);
+
+/**
+ * Close an OpenCAPI function
+ *
+ * This will free any AFUs previously retrieved from the function, and
+ * detach and associated contexts. The contexts must by freed by the caller.
+ *
+ * @fn: The OpenCAPI function to close
+ *
+ */
+void ocxl_function_close(struct ocxl_fn *fn);
+
+// OpenCAPI contexts
 /**
  * Allocate space for a new OpenCAPI context
  *
@@ -102,6 +167,8 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr,
  */
 int ocxl_context_detach(struct ocxl_context *ctx);
 
+// OpenCAPI MMIO accesses
+
 /**
  * Read a 32 bit value from global MMIO
  *
@@ -206,12 +273,39 @@ int ocxl_global_mmio_clear32(struct ocxl_afu *afu, size_t offset,
 int ocxl_global_mmio_clear64(struct ocxl_afu *afu, size_t offset,
 				enum ocxl_endian endian, u64 mask);
 
-/*
- * Read the configuration space of a function and fill in a
- * ocxl_fn_config structure with all the function details
+// AFU Metadata
+
+/**
+ * Get a pointer to the config for an AFU
+ *
+ * @afu: a pointer to the AFU to get the config for
+ *
+ * Returns a pointer to the AFU config
  */
-int ocxl_config_read_function(struct pci_dev *dev,
-				struct ocxl_fn_config *fn);
+struct ocxl_afu_config *ocxl_afu_config(struct ocxl_afu *afu);
+
+/**
+ * Assign opaque hardware specific information to an OpenCAPI AFU.
+ *
+ * @dev: The PCI device associated with the OpenCAPI device
+ * @private: the opaque hardware specific information to assign to the driver
+ * @private_release: A callback to free the private data
+ */
+void ocxl_afu_set_private(struct ocxl_afu *afu, void *private,
+			void (*private_release)(void *private));
+
+/**
+ * Fetch the hardware specific information associated with an external OpenCAPI
+ * AFU. This may be consumed by an external OpenCAPI driver.
+ *
+ * @afu: The AFU
+ *
+ * Returns the opaque pointer associated with the device, or NULL if not set
+ */
+void *ocxl_afu_get_private(struct ocxl_afu *dev);
+
+
+// Functions left here are for compatibility with the cxlflash driver
 
 /*
  * Read the configuration space of a function for the AFU specified by
@@ -298,6 +392,13 @@ int ocxl_config_set_TL(struct pci_dev *dev, int tl_dvsec);
 int ocxl_config_terminate_pasid(struct pci_dev *dev,
 				int afu_control_offset, int pasid);
 
+/*
+ * Read the configuration space of a function and fill in a
+ * ocxl_fn_config structure with all the function details
+ */
+int ocxl_config_read_function(struct pci_dev *dev,
+				struct ocxl_fn_config *fn);
+
 /*
  * Set up the opencapi link for the function.
  *
-- 
2.20.1

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