cxl/mbox: Move mailbox and other non-PCI specific infrastructure to the core

Now that the internals of mailbox operations are abstracted from the PCI
specifics a bulk of infrastructure can move to the core.

The CXL_PMEM driver intends to proxy LIBNVDIMM UAPI and driver requests
to the equivalent functionality provided by the CXL hardware mailbox
interface. In support of that intent move the mailbox implementation to
a shared location for the CXL_PCI driver native IOCTL path and CXL_PMEM
nvdimm command proxy path to share.

A unit test framework seeks to implement a unit test backend transport
for mailbox commands to communicate mocked up payloads. It can reuse all
of the mailbox infrastructure minus the PCI specifics, so that also gets
moved to the core.

Finally with the mailbox infrastructure and ioctl handling being
transport generic there is no longer any need to pass file
file_operations to devm_cxl_add_memdev(). That allows all the ioctl
boilerplate to move into the core for unit test reuse.

No functional change intended, just code movement.

Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163116435233.2460985.16197340449713287180.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 72 insertions, 9 deletions

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 331ef7d6c598..df2ba87238c2 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -8,6 +8,8 @@
 #include <cxlmem.h>
 #include "core.h"
 
+static DECLARE_RWSEM(cxl_memdev_rwsem);
+
 /*
  * An entire PCI topology full of devices should be enough for any
  * config
@@ -132,16 +134,21 @@ static const struct device_type cxl_memdev_type = {
 	.groups = cxl_memdev_attribute_groups,
 };
 
+static void cxl_memdev_shutdown(struct device *dev)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+
+	down_write(&cxl_memdev_rwsem);
+	cxlmd->cxlm = NULL;
+	up_write(&cxl_memdev_rwsem);
+}
+
 static void cxl_memdev_unregister(void *_cxlmd)
 {
 	struct cxl_memdev *cxlmd = _cxlmd;
 	struct device *dev = &cxlmd->dev;
-	struct cdev *cdev = &cxlmd->cdev;
-	const struct cdevm_file_operations *cdevm_fops;
-
-	cdevm_fops = container_of(cdev->ops, typeof(*cdevm_fops), fops);
-	cdevm_fops->shutdown(dev);
 
+	cxl_memdev_shutdown(dev);
 	cdev_device_del(&cxlmd->cdev, dev);
 	put_device(dev);
 }
@@ -180,16 +187,72 @@ err:
 	return ERR_PTR(rc);
 }
 
+static long __cxl_memdev_ioctl(struct cxl_memdev *cxlmd, unsigned int cmd,
+			       unsigned long arg)
+{
+	switch (cmd) {
+	case CXL_MEM_QUERY_COMMANDS:
+		return cxl_query_cmd(cxlmd, (void __user *)arg);
+	case CXL_MEM_SEND_COMMAND:
+		return cxl_send_cmd(cxlmd, (void __user *)arg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static long cxl_memdev_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct cxl_memdev *cxlmd = file->private_data;
+	int rc = -ENXIO;
+
+	down_read(&cxl_memdev_rwsem);
+	if (cxlmd->cxlm)
+		rc = __cxl_memdev_ioctl(cxlmd, cmd, arg);
+	up_read(&cxl_memdev_rwsem);
+
+	return rc;
+}
+
+static int cxl_memdev_open(struct inode *inode, struct file *file)
+{
+	struct cxl_memdev *cxlmd =
+		container_of(inode->i_cdev, typeof(*cxlmd), cdev);
+
+	get_device(&cxlmd->dev);
+	file->private_data = cxlmd;
+
+	return 0;
+}
+
+static int cxl_memdev_release_file(struct inode *inode, struct file *file)
+{
+	struct cxl_memdev *cxlmd =
+		container_of(inode->i_cdev, typeof(*cxlmd), cdev);
+
+	put_device(&cxlmd->dev);
+
+	return 0;
+}
+
+static const struct file_operations cxl_memdev_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = cxl_memdev_ioctl,
+	.open = cxl_memdev_open,
+	.release = cxl_memdev_release_file,
+	.compat_ioctl = compat_ptr_ioctl,
+	.llseek = noop_llseek,
+};
+
 struct cxl_memdev *
-devm_cxl_add_memdev(struct cxl_mem *cxlm,
-		    const struct cdevm_file_operations *cdevm_fops)
+devm_cxl_add_memdev(struct cxl_mem *cxlm)
 {
 	struct cxl_memdev *cxlmd;
 	struct device *dev;
 	struct cdev *cdev;
 	int rc;
 
-	cxlmd = cxl_memdev_alloc(cxlm, &cdevm_fops->fops);
+	cxlmd = cxl_memdev_alloc(cxlm, &cxl_memdev_fops);
 	if (IS_ERR(cxlmd))
 		return cxlmd;
 
@@ -219,7 +282,7 @@ err:
 	 * The cdev was briefly live, shutdown any ioctl operations that
 	 * saw that state.
 	 */
-	cdevm_fops->shutdown(dev);
+	cxl_memdev_shutdown(dev);
 	put_device(dev);
 	return ERR_PTR(rc);
 }