[16/18] dmaengine: idxd: create user driver for wq 'device'

Commit Message

Dave Jiang May 21, 2021, 10:22 p.m. UTC

The original architecture of /sys/bus/dsa invented a scheme whereby a
single entry in the list of bus drivers, /sys/bus/drivers/dsa, handled
all device types and internally routed them to different drivers.
Those internal drivers were invisible to userspace. Now, as
/sys/bus/dsa wants to grow support for alternate drivers for a given
device, for example vfio-mdev instead of kernel-internal-dmaengine, a
proper bus device-driver model is needed. The first step in that process
is separating the existing omnibus/implicit "dsa" driver into proper
individual drivers registered on /sys/bus/dsa. Establish the
idxd_user_drv driver that controls the enabling and disabling of the
wq and also register and unregister a char device to allow user space
to mmap the descriptor submission portal.

The cdev related bits are moved to the cdev driver probe/remove and out of
the drv_enabe/disable_wq() calls. These bits are exclusive to the cdev
operation and not part of the generic enable/disable of the wq device.

Reviewed-by: Dan Williams <[e-mail]>
Signed-off-by: Dave Jiang <[e-mail]>
---
 drivers/dma/idxd/cdev.c   |   53 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/dma/idxd/device.c |   14 ------------
 drivers/dma/idxd/idxd.h   |    1 +
 drivers/dma/idxd/init.c   |    7 ++++++
 4 files changed, 61 insertions(+), 14 deletions(-)

Patch

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index 0b0c8d1c4d6c..32254996fbfb 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -303,6 +303,59 @@  void idxd_wq_del_cdev(struct idxd_wq *wq)
 	put_device(cdev_dev(idxd_cdev));
 }
 
+static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
+{
+	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
+	struct idxd_device *idxd = wq->idxd;
+	int rc;
+
+	if (idxd->state != IDXD_DEV_ENABLED)
+		return -ENXIO;
+
+	mutex_lock(&wq->wq_lock);
+	wq->type = IDXD_WQT_USER;
+	rc = __drv_enable_wq(wq);
+	if (rc < 0)
+		goto err;
+
+	rc = idxd_wq_add_cdev(wq);
+	if (rc < 0)
+		goto err_cdev;
+
+	mutex_unlock(&wq->wq_lock);
+	return 0;
+
+err_cdev:
+	__drv_disable_wq(wq);
+err:
+	wq->type = IDXD_WQT_NONE;
+	mutex_unlock(&wq->wq_lock);
+	return rc;
+}
+
+static void idxd_user_drv_remove(struct idxd_dev *idxd_dev)
+{
+	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
+
+	mutex_lock(&wq->wq_lock);
+	idxd_wq_del_cdev(wq);
+	__drv_disable_wq(wq);
+	wq->type = IDXD_WQT_NONE;
+	mutex_unlock(&wq->wq_lock);
+}
+
+static enum idxd_dev_type dev_types[] = {
+	IDXD_DEV_WQ,
+	IDXD_DEV_NONE,
+};
+
+struct idxd_device_driver idxd_user_drv = {
+	.probe = idxd_user_drv_probe,
+	.remove = idxd_user_drv_remove,
+	.name = "user",
+	.type = dev_types,
+};
+
 int idxd_cdev_register(void)
 {
 	int rc, i;
diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 85ee5d65c724..2ead07909459 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -1158,19 +1158,8 @@  int __drv_enable_wq(struct idxd_wq *wq)
 	}
 
 	wq->client_count = 0;
-
-	if (is_idxd_wq_cdev(wq)) {
-		rc = idxd_wq_add_cdev(wq);
-		if (rc < 0) {
-			dev_dbg(dev, "wq %d cdev creation failed\n", wq->id);
-			goto err_client;
-		}
-	}
-
 	return 0;
 
-err_client:
-	idxd_wq_unmap_portal(wq);
 err_map_portal:
 	rc = idxd_wq_disable(wq);
 	if (rc < 0)
@@ -1196,9 +1185,6 @@  void __drv_disable_wq(struct idxd_wq *wq)
 
 	lockdep_assert_held(&wq->wq_lock);
 
-	if (is_idxd_wq_cdev(wq))
-		idxd_wq_del_cdev(wq);
-
 	if (idxd_wq_refcount(wq))
 		dev_warn(dev, "Clients has claim on wq %d: %d\n",
 			 wq->id, idxd_wq_refcount(wq));
diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 43ec1472ce25..b5c485e17d11 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -60,6 +60,7 @@  struct idxd_device_driver {
 extern struct idxd_device_driver dsa_drv;
 extern struct idxd_device_driver idxd_drv;
 extern struct idxd_device_driver idxd_dmaengine_drv;
+extern struct idxd_device_driver idxd_user_drv;
 
 struct idxd_irq_entry {
 	struct idxd_device *idxd;
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 72f49e072e1c..bde0126d4f85 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -789,6 +789,10 @@  static int __init idxd_init_module(void)
 	if (err < 0)
 		goto err_idxd_dmaengine_driver_register;
 
+	err = idxd_driver_register(&idxd_user_drv);
+	if (err < 0)
+		goto err_idxd_user_driver_register;
+
 	err = idxd_driver_register(&dsa_drv);
 	if (err < 0)
 		goto err_dsa_driver_register;
@@ -808,6 +812,8 @@  static int __init idxd_init_module(void)
 err_cdev_register:
 	idxd_driver_unregister(&dsa_drv);
 err_dsa_driver_register:
+	idxd_driver_unregister(&idxd_user_drv);
+err_idxd_user_driver_register:
 	idxd_driver_unregister(&idxd_dmaengine_drv);
 err_idxd_dmaengine_driver_register:
 	idxd_driver_unregister(&idxd_drv);
@@ -819,6 +825,7 @@  module_init(idxd_init_module);
 
 static void __exit idxd_exit_module(void)
 {
+	idxd_driver_unregister(&idxd_user_drv);
 	idxd_driver_unregister(&idxd_dmaengine_drv);
 	idxd_driver_unregister(&idxd_drv);
 	idxd_driver_unregister(&dsa_drv);