virtio: expose features in sysfs
Each device negotiates feature bits; expose these in sysfs to help
diagnostics and debugging.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 3f52c76..bd074525 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -31,11 +31,27 @@
return sprintf(buf, "virtio:d%08Xv%08X\n",
dev->id.device, dev->id.vendor);
}
+static ssize_t features_show(struct device *_d,
+ struct device_attribute *attr, char *buf)
+{
+ struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
+ unsigned int i;
+ ssize_t len = 0;
+
+ /* We actually represent this as a bitstring, as it could be
+ * arbitrary length in future. */
+ for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
+ len += sprintf(buf+len, "%c",
+ test_bit(i, dev->features) ? '1' : '0');
+ len += sprintf(buf+len, "\n");
+ return len;
+}
static struct device_attribute virtio_dev_attrs[] = {
__ATTR_RO(device),
__ATTR_RO(vendor),
__ATTR_RO(status),
__ATTR_RO(modalias),
+ __ATTR_RO(features),
__ATTR_NULL
};
