dmaengine: idxd: create dmaengine driver for wq 'device'

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_dmaengine_drv driver that controls the enabling and disabling of the
wq and also register and unregister the dma channel.

idxd_wq_alloc_resources() and idxd_wq_free_resources() also get moved to
the dmaengine driver. The resources (dma descriptors allocation and setup)
are only used by the dmaengine driver and should only happen when it loads.

The char dev driver (cdev) related bits are left in the __drv_enable_wq()
and __drv_disable_wq() calls to be moved when we split out the char dev
driver just like how the dmaengine driver is split out.

WQ autoload support is not expected currently. With the amount of
configuration needed for the device, the wq is always expected to
be enabled by a tool (or via sysfs) rather than auto enabled at driver
load.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/162637467033.744545.12330636655625405394.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 5 insertions, 35 deletions

diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 12ae3f1639f1..4dcc9431ae3d 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -1130,7 +1130,7 @@ int idxd_device_load_config(struct idxd_device *idxd)
 	return 0;
 }
 
-static int __drv_enable_wq(struct idxd_wq *wq)
+int __drv_enable_wq(struct idxd_wq *wq)
 {
 	struct idxd_device *idxd = wq->idxd;
 	struct device *dev = &idxd->pdev->dev;
@@ -1178,12 +1178,7 @@ static int __drv_enable_wq(struct idxd_wq *wq)
 		}
 	}
 
-	rc = idxd_wq_alloc_resources(wq);
-	if (rc < 0) {
-		dev_dbg(dev, "wq resource alloc failed\n");
-		goto err;
-	}
-
+	rc = 0;
 	spin_lock_irqsave(&idxd->dev_lock, flags);
 	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
 		rc = idxd_device_config(idxd);
@@ -1207,21 +1202,7 @@ static int __drv_enable_wq(struct idxd_wq *wq)
 
 	wq->client_count = 0;
 
-	if (wq->type == IDXD_WQT_KERNEL) {
-		rc = idxd_wq_init_percpu_ref(wq);
-		if (rc < 0) {
-			dev_dbg(dev, "wq %d percpu_ref setup failed\n", wq->id);
-			goto err_cpu_ref;
-		}
-	}
-
-	if (is_idxd_wq_dmaengine(wq)) {
-		rc = idxd_register_dma_channel(wq);
-		if (rc < 0) {
-			dev_dbg(dev, "wq %d DMA channel register failed\n", wq->id);
-			goto err_client;
-		}
-	} else if (is_idxd_wq_cdev(wq)) {
+	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);
@@ -1229,12 +1210,9 @@ static int __drv_enable_wq(struct idxd_wq *wq)
 		}
 	}
 
-	dev_info(dev, "wq %s enabled\n", dev_name(wq_confdev(wq)));
 	return 0;
 
 err_client:
-	idxd_wq_quiesce(wq);
-err_cpu_ref:
 	idxd_wq_unmap_portal(wq);
 err_map_portal:
 	rc = idxd_wq_disable(wq, false);
@@ -1254,19 +1232,14 @@ int drv_enable_wq(struct idxd_wq *wq)
 	return rc;
 }
 
-static void __drv_disable_wq(struct idxd_wq *wq)
+void __drv_disable_wq(struct idxd_wq *wq)
 {
 	struct idxd_device *idxd = wq->idxd;
 	struct device *dev = &idxd->pdev->dev;
 
 	lockdep_assert_held(&wq->wq_lock);
 
-	if (wq->type == IDXD_WQT_KERNEL)
-		idxd_wq_quiesce(wq);
-
-	if (is_idxd_wq_dmaengine(wq))
-		idxd_unregister_dma_channel(wq);
-	else if (is_idxd_wq_cdev(wq))
+	if (is_idxd_wq_cdev(wq))
 		idxd_wq_del_cdev(wq);
 
 	if (idxd_wq_refcount(wq))
@@ -1278,10 +1251,7 @@ static void __drv_disable_wq(struct idxd_wq *wq)
 	idxd_wq_drain(wq);
 	idxd_wq_reset(wq);
 
-	idxd_wq_free_resources(wq);
 	wq->client_count = 0;
-
-	dev_info(dev, "wq %s disabled\n", dev_name(wq_confdev(wq)));
 }
 
 void drv_disable_wq(struct idxd_wq *wq)