ocxl: Create a clear delineation between ocxl backend & frontend

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@d-silva.org>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 100 insertions, 42 deletions

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 009e09b7ded5..7a38ea5af9db 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -17,70 +17,60 @@ 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
-	 * minor number of a device is removed from the idr, the ref count of
+	 * info reference is removed from the idr, the ref count of
 	 * 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;
-	}
+	if (!ctx)
+		return -ENOMEM;
 
-	rc = ocxl_context_init(ctx, afu, inode->i_mapping);
+	rc = ocxl_context_init(ctx, info->afu, inode->i_mapping);
 	if (rc)
-		goto put_afu;
+		return rc;
+
 	file->private_data = ctx;
-	ocxl_afu_put(afu);
 	return 0;
-
-put_afu:
-	ocxl_afu_put(afu);
-	return rc;
 }
 
 static long afu_ioctl_attach(struct ocxl_context *ctx,
@@ -204,11 +194,16 @@ 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) {
@@ -468,39 +463,102 @@ static const struct file_operations ocxl_afu_fops = {
 	.release        = afu_release,
 };
 
-int ocxl_create_cdev(struct ocxl_afu *afu)
+// Free the info struct
+static void info_release(struct device *dev)
+{
+	struct ocxl_file_info *info = container_of(dev, struct ocxl_file_info, dev);
+
+	free_minor(info);
+	ocxl_afu_put(info->afu);
+	kfree(info);
+}
+
+static int ocxl_file_make_visible(struct ocxl_file_info *info)
 {
 	int rc;
 
-	cdev_init(&afu->cdev, &ocxl_afu_fops);
-	rc = cdev_add(&afu->cdev, afu->dev.devt, 1);
+	cdev_init(&info->cdev, &ocxl_afu_fops);
+	rc = cdev_add(&info->cdev, info->dev.devt, 1);
 	if (rc) {
-		dev_err(&afu->dev, "Unable to add afu char device: %d\n", rc);
+		dev_err(&info->dev, "Unable to add afu char device: %d\n", rc);
 		return rc;
 	}
+
 	return 0;
 }
 
-void ocxl_destroy_cdev(struct ocxl_afu *afu)
+static void ocxl_file_make_invisible(struct ocxl_file_info *info)
 {
-	cdev_del(&afu->cdev);
+	cdev_del(&info->cdev);
 }
 
-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)
+	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;
+	info->dev.release = info_release;
+
+	info->afu = afu;
+	ocxl_afu_get(afu);
+
+	rc = dev_set_name(&info->dev, "%s.%s.%hhu",
+		afu->config.name, dev_name(&pci_dev->dev), afu->config.idx);
+	if (rc)
+		goto err_put;
+
+	rc = device_register(&info->dev);
+	if (rc)
+		goto err_put;
+
+	rc = ocxl_sysfs_register_afu(info);
+	if (rc)
+		goto err_unregister;
+
+	rc = ocxl_file_make_visible(info);
+	if (rc)
+		goto err_unregister;
+
+	ocxl_afu_set_private(afu, info);
+
+	return 0;
+
+err_unregister:
+	ocxl_sysfs_unregister_afu(info); // safe to call even if register failed
+	device_unregister(&info->dev);
+err_put:
+	ocxl_afu_put(afu);
+	free_minor(info);
+	kfree(info);
+	return rc;
 }
 
-void ocxl_unregister_afu(struct ocxl_afu *afu)
+void ocxl_file_unregister_afu(struct ocxl_afu *afu)
 {
-	free_afu_minor(afu);
+	struct ocxl_file_info *info = ocxl_afu_get_private(afu);
+
+	if (!info)
+		return;
+
+	ocxl_file_make_invisible(info);
+	ocxl_sysfs_unregister_afu(info);
+	device_unregister(&info->dev);
 }
 
 static char *ocxl_devnode(struct device *dev, umode_t *mode)