diff options
Diffstat (limited to 'include/linux/virtio_config.h')
| -rw-r--r-- | include/linux/virtio_config.h | 81 |
1 files changed, 44 insertions, 37 deletions
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index d581b2914b34..50db245c81ad 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -16,27 +16,20 @@ #define VIRTIO_CONFIG_S_FAILED 0x80 #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 +45,15 @@ 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 +65,52 @@ 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 */ |