[PATCH 2/2] dmaengine: idxd: Make max batch size attributes in sysfs invisible for Intel IAA

[Xiaochen Shen <xiaochen.shen@intel.com>]

In current code, dev.max_batch_size and wq.max_batch_size attributes in
sysfs are exposed to user to show or update the values.

From Intel IAA spec [1], Intel IAA does not support batch processing. So
these sysfs attributes should not be supported on IAA device.

Fix this issue by making the attributes of max_batch_size invisible in
sysfs through is_visible() filter when the device is IAA.

Add description in the ABI documentation to mention that the attributes
are not visible when the device does not support batch.

[1]: https://cdrdv2.intel.com/v1/dl/getContent/721858

Fixes: e7184b159dd3 ("dmaengine: idxd: add support for configurable max wq batch size")
Fixes: c52ca478233c ("dmaengine: idxd: add configuration component of driver")
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
---
 .../ABI/stable/sysfs-driver-dma-idxd          |  2 ++
 drivers/dma/idxd/sysfs.c                      | 30 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-driver-dma-idxd b/Documentation/ABI/stable/sysfs-driver-dma-idxd
index 0c2b613f2373..da3f6d01e0bd 100644
--- a/Documentation/ABI/stable/sysfs-driver-dma-idxd
+++ b/Documentation/ABI/stable/sysfs-driver-dma-idxd
@@ -22,6 +22,7 @@ Date:           Oct 25, 2019
 KernelVersion:  5.6.0
 Contact:        dmaengine@vger.kernel.org
 Description:    The largest number of work descriptors in a batch.
+		It's not visible when the device does not support batch.
 
 What:           /sys/bus/dsa/devices/dsa<m>/max_work_queues_size
 Date:           Oct 25, 2019
@@ -205,6 +206,7 @@ KernelVersion:	5.10.0
 Contact:	dmaengine@vger.kernel.org
 Description:	The max batch size for this workqueue. Cannot exceed device
 		max batch size. Configurable parameter.
+		It's not visible when the device does not support batch.
 
 What:		/sys/bus/dsa/devices/wq<m>.<n>/ats_disable
 Date:		Nov 13, 2020
diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
index fa729fac4b97..b13a8cc4d24f 100644
--- a/drivers/dma/idxd/sysfs.c
+++ b/drivers/dma/idxd/sysfs.c
@@ -1055,6 +1055,20 @@ static ssize_t wq_enqcmds_retries_store(struct device *dev, struct device_attrib
 static struct device_attribute dev_attr_wq_enqcmds_retries =
 		__ATTR(enqcmds_retries, 0644, wq_enqcmds_retries_show, wq_enqcmds_retries_store);
 
+static umode_t idxd_wq_visible(struct kobject *kobj,
+			       struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct idxd_wq *wq = confdev_to_wq(dev);
+
+	/* Intel IAA does not support batch processing, make it invisible */
+	if (attr == &dev_attr_wq_max_batch_size.attr &&
+			wq->idxd->data->type == IDXD_TYPE_IAX)
+		return 0;
+
+	return attr->mode;
+}
+
 static struct attribute *idxd_wq_attributes[] = {
 	&dev_attr_wq_clients.attr,
 	&dev_attr_wq_state.attr,
@@ -1077,6 +1091,7 @@ static struct attribute *idxd_wq_attributes[] = {
 
 static const struct attribute_group idxd_wq_attribute_group = {
 	.attrs = idxd_wq_attributes,
+	.is_visible = idxd_wq_visible,
 };
 
 static const struct attribute_group *idxd_wq_attribute_groups[] = {
@@ -1366,6 +1381,20 @@ static ssize_t cmd_status_store(struct device *dev, struct device_attribute *att
 }
 static DEVICE_ATTR_RW(cmd_status);
 
+static umode_t idxd_device_visible(struct kobject *kobj,
+				   struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct idxd_device *idxd = confdev_to_idxd(dev);
+
+	/* Intel IAA does not support batch processing, make it invisible */
+	if (attr == &dev_attr_max_batch_size.attr &&
+			idxd->data->type == IDXD_TYPE_IAX)
+		return 0;
+
+	return attr->mode;
+}
+
 static struct attribute *idxd_device_attributes[] = {
 	&dev_attr_version.attr,
 	&dev_attr_max_groups.attr,
@@ -1393,6 +1422,7 @@ static struct attribute *idxd_device_attributes[] = {
 
 static const struct attribute_group idxd_device_attribute_group = {
 	.attrs = idxd_device_attributes,
+	.is_visible = idxd_device_visible,
 };
 
 static const struct attribute_group *idxd_attribute_groups[] = {
-- 
2.18.4