dmaengine: idxd: export hw version through sysfs

Some user apps would like to know the hardware version in order to
determine the variation of the hardware. Export the hardware version number
to userspace via sysfs.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/158696714008.39484.13401950732606906479.stgit@djiang5-desk3.ch.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/ABI/stable/sysfs-driver-dma-idxd

+What:		sys/bus/dsa/devices/dsa<m>/version
+Date:		Apr 15, 2020
+KernelVersion:	5.8.0
+Contact:	dmaengine@vger.kernel.org
+Description:	The hardware version number.
+
 What:           sys/bus/dsa/devices/dsa<m>/cdev_major
 Date:           Oct 25, 2019
 KernelVersion: 	5.6.0

drivers/dma/idxd/sysfs.c

@@ -1092,6 +1092,16 @@ static const struct attribute_group *idxd_wq_attribute_groups[] = {
 };
 
 /* IDXD device attribs */
+static ssize_t version_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct idxd_device *idxd =
+		container_of(dev, struct idxd_device, conf_dev);
+
+	return sprintf(buf, "%#x\n", idxd->hw.version);
+}
+static DEVICE_ATTR_RO(version);
+
 static ssize_t max_work_queues_size_show(struct device *dev,
 					 struct device_attribute *attr,
 					 char *buf)
@@ -1313,6 +1323,7 @@ static ssize_t cdev_major_show(struct device *dev,
 static DEVICE_ATTR_RO(cdev_major);
 
 static struct attribute *idxd_device_attributes[] = {
+	&dev_attr_version.attr,
 	&dev_attr_max_groups.attr,
 	&dev_attr_max_work_queues.attr,
 	&dev_attr_max_work_queues_size.attr,