X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Flinux%2Fvirtio_config.h;h=f364bbf63c3413547738ae4028b399577bc76650;hb=18ce3751ccd488c78d3827e9f6bf54e6322676fb;hp=d581b2914b342cbbe83744bc15762fb8718a81a3;hpb=8f859016ea49cd8d7c743533bd1ab3db9a813ffa;p=linux-2.6

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index d581b2914b..f364bbf63c 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -15,28 +15,25 @@
 /* We've given up on this device. */
 #define VIRTIO_CONFIG_S_FAILED		0x80
 
+/* Do we get callbacks when the ring is completely used, even if we've
+ * suppressed them? */
+#define VIRTIO_F_NOTIFY_ON_EMPTY	24
+
 #ifdef __KERNEL__
-struct virtio_device;
+#include <linux/virtio.h>
 
 /**
  * virtio_config_ops - operations for configuring a virtio device
- * @feature: search for a feature in this config
- *	vdev: the virtio_device
- *	bit: the feature bit
- *	Returns true if the feature is supported.  Acknowledges the feature
- *	so the host can see it.
  * @get: read the value of a configuration field
  *	vdev: the virtio_device
  *	offset: the offset of the configuration field
  *	buf: the buffer to write the field value into.
  *	len: the length of the buffer
- *	Note that contents are conventionally little-endian.
  * @set: write the value of a configuration field
  *	vdev: the virtio_device
  *	offset: the offset of the configuration field
  *	buf: the buffer to read the field value from.
  *	len: the length of the buffer
- *	Note that contents are conventionally little-endian.
  * @get_status: read the status byte
  *	vdev: the virtio_device
  *	Returns the status byte
@@ -52,10 +49,15 @@ struct virtio_device;
  *	callback: the virqtueue callback
  *	Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
  * @del_vq: free a virtqueue found by find_vq().
+ * @get_features: get the array of feature bits for this device.
+ *	vdev: the virtio_device
+ *	Returns the first 32 feature bits (all we currently need).
+ * @set_features: confirm what device features we'll be using.
+ *	vdev: the virtio_device
+ *	feature: the first 32 feature bits
  */
 struct virtio_config_ops
 {
-	bool (*feature)(struct virtio_device *vdev, unsigned bit);
 	void (*get)(struct virtio_device *vdev, unsigned offset,
 		    void *buf, unsigned len);
 	void (*set)(struct virtio_device *vdev, unsigned offset,
@@ -67,43 +69,52 @@ struct virtio_config_ops
 				     unsigned index,
 				     void (*callback)(struct virtqueue *));
 	void (*del_vq)(struct virtqueue *vq);
+	u32 (*get_features)(struct virtio_device *vdev);
+	void (*set_features)(struct virtio_device *vdev, u32 features);
 };
 
+/* If driver didn't advertise the feature, it will never appear. */
+void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
+					 unsigned int fbit);
+
 /**
- * virtio_config_val - look for a feature and get a single virtio config.
- * @vdev: the virtio device
+ * virtio_has_feature - helper to determine if this device has this feature.
+ * @vdev: the device
  * @fbit: the feature bit
- * @offset: the type to search for.
- * @val: a pointer to the value to fill in.
- *
- * The return value is -ENOENT if the feature doesn't exist.  Otherwise
- * the value is endian-corrected and returned in v. */
-#define virtio_config_val(vdev, fbit, offset, v) ({			\
-	int _err;							\
-	if ((vdev)->config->feature((vdev), (fbit))) {			\
-		__virtio_config_val((vdev), (offset), (v));		\
-		_err = 0;						\
-	} else								\
-		_err = -ENOENT;						\
-	_err;								\
-})
+ */
+static inline bool virtio_has_feature(const struct virtio_device *vdev,
+				      unsigned int fbit)
+{
+	/* Did you forget to fix assumptions on max features? */
+	if (__builtin_constant_p(fbit))
+		BUILD_BUG_ON(fbit >= 32);
+
+	virtio_check_driver_offered_feature(vdev, fbit);
+	return test_bit(fbit, vdev->features);
+}
 
 /**
- * __virtio_config_val - get a single virtio config without feature check.
+ * virtio_config_val - look for a feature and get a virtio config entry.
  * @vdev: the virtio device
+ * @fbit: the feature bit
  * @offset: the type to search for.
  * @val: a pointer to the value to fill in.
  *
- * The value is endian-corrected and returned in v. */
-#define __virtio_config_val(vdev, offset, v) do {			\
-	BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2		\
-		     && sizeof(*(v)) != 4 && sizeof(*(v)) != 8);	\
-	(vdev)->config->get((vdev), (offset), (v), sizeof(*(v)));	\
-	switch (sizeof(*(v))) {						\
-	case 2: le16_to_cpus((__u16 *) v); break;			\
-	case 4: le32_to_cpus((__u32 *) v); break;			\
-	case 8: le64_to_cpus((__u64 *) v); break;			\
-	}								\
-} while(0)
+ * The return value is -ENOENT if the feature doesn't exist.  Otherwise
+ * the config value is copied into whatever is pointed to by v. */
+#define virtio_config_val(vdev, fbit, offset, v) \
+	virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
+
+static inline int virtio_config_buf(struct virtio_device *vdev,
+				    unsigned int fbit,
+				    unsigned int offset,
+				    void *buf, unsigned len)
+{
+	if (!virtio_has_feature(vdev, fbit))
+		return -ENOENT;
+
+	vdev->config->get(vdev, offset, buf, len);
+	return 0;
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_VIRTIO_CONFIG_H */