1 #ifndef _LINUX_VIRTIO_CONFIG_H 2 #define _LINUX_VIRTIO_CONFIG_H 3 /* Virtio devices use a standardized configuration space to define their 4 * features and pass configuration information, but each implementation can 5 * store and access that space differently. */ 6 #include <linux/types.h> 7 8 /* Status byte for guest to report progress, and synchronize features. */ 9 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */ 10 #define VIRTIO_CONFIG_S_ACKNOWLEDGE 1 11 /* We have found a driver for the device. */ 12 #define VIRTIO_CONFIG_S_DRIVER 2 13 /* Driver has used its parts of the config, and is happy */ 14 #define VIRTIO_CONFIG_S_DRIVER_OK 4 15 /* We've given up on this device. */ 16 #define VIRTIO_CONFIG_S_FAILED 0x80 17 18 #ifdef __KERNEL__ 19 #include <linux/virtio.h> 20 21 /** 22 * virtio_config_ops - operations for configuring a virtio device 23 * @get: read the value of a configuration field 24 * vdev: the virtio_device 25 * offset: the offset of the configuration field 26 * buf: the buffer to write the field value into. 27 * len: the length of the buffer 28 * @set: write the value of a configuration field 29 * vdev: the virtio_device 30 * offset: the offset of the configuration field 31 * buf: the buffer to read the field value from. 32 * len: the length of the buffer 33 * @get_status: read the status byte 34 * vdev: the virtio_device 35 * Returns the status byte 36 * @set_status: write the status byte 37 * vdev: the virtio_device 38 * status: the new status byte 39 * @reset: reset the device 40 * vdev: the virtio device 41 * After this, status and feature negotiation must be done again 42 * @find_vq: find a virtqueue and instantiate it. 43 * vdev: the virtio_device 44 * index: the 0-based virtqueue number in case there's more than one. 45 * callback: the virqtueue callback 46 * Returns the new virtqueue or ERR_PTR() (eg. -ENOENT). 47 * @del_vq: free a virtqueue found by find_vq(). 48 * @get_features: get the array of feature bits for this device. 49 * vdev: the virtio_device 50 * Returns the first 32 feature bits (all we currently need). 51 * @set_features: confirm what device features we'll be using. 52 * vdev: the virtio_device 53 * feature: the first 32 feature bits 54 */ 55 struct virtio_config_ops 56 { 57 void (*get)(struct virtio_device *vdev, unsigned offset, 58 void *buf, unsigned len); 59 void (*set)(struct virtio_device *vdev, unsigned offset, 60 const void *buf, unsigned len); 61 u8 (*get_status)(struct virtio_device *vdev); 62 void (*set_status)(struct virtio_device *vdev, u8 status); 63 void (*reset)(struct virtio_device *vdev); 64 struct virtqueue *(*find_vq)(struct virtio_device *vdev, 65 unsigned index, 66 void (*callback)(struct virtqueue *)); 67 void (*del_vq)(struct virtqueue *vq); 68 u32 (*get_features)(struct virtio_device *vdev); 69 void (*set_features)(struct virtio_device *vdev, u32 features); 70 }; 71 72 /* If driver didn't advertise the feature, it will never appear. */ 73 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 74 unsigned int fbit); 75 76 /** 77 * virtio_has_feature - helper to determine if this device has this feature. 78 * @vdev: the device 79 * @fbit: the feature bit 80 */ 81 static inline bool virtio_has_feature(const struct virtio_device *vdev, 82 unsigned int fbit) 83 { 84 /* Did you forget to fix assumptions on max features? */ 85 if (__builtin_constant_p(fbit)) 86 BUILD_BUG_ON(fbit >= 32); 87 88 virtio_check_driver_offered_feature(vdev, fbit); 89 return test_bit(fbit, vdev->features); 90 } 91 92 /** 93 * virtio_config_val - look for a feature and get a virtio config entry. 94 * @vdev: the virtio device 95 * @fbit: the feature bit 96 * @offset: the type to search for. 97 * @val: a pointer to the value to fill in. 98 * 99 * The return value is -ENOENT if the feature doesn't exist. Otherwise 100 * the config value is copied into whatever is pointed to by v. */ 101 #define virtio_config_val(vdev, fbit, offset, v) \ 102 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(v)) 103 104 static inline int virtio_config_buf(struct virtio_device *vdev, 105 unsigned int fbit, 106 unsigned int offset, 107 void *buf, unsigned len) 108 { 109 if (!virtio_has_feature(vdev, fbit)) 110 return -ENOENT; 111 112 vdev->config->get(vdev, offset, buf, len); 113 return 0; 114 } 115 #endif /* __KERNEL__ */ 116 #endif /* _LINUX_VIRTIO_CONFIG_H */ 117