1#ifndef _LINUX_VIRTIO_CONFIG_H 2#define _LINUX_VIRTIO_CONFIG_H 3/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so 4 * anyone can use the definitions to implement compatible drivers/servers. */ 5 6/* Virtio devices use a standardized configuration space to define their 7 * features and pass configuration information, but each implementation can 8 * store and access that space differently. */ 9#include <linux/types.h> 10 11/* Status byte for guest to report progress, and synchronize features. */ 12/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */ 13#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1 14/* We have found a driver for the device. */ 15#define VIRTIO_CONFIG_S_DRIVER 2 16/* Driver has used its parts of the config, and is happy */ 17#define VIRTIO_CONFIG_S_DRIVER_OK 4 18/* We've given up on this device. */ 19#define VIRTIO_CONFIG_S_FAILED 0x80 20 21/* Some virtio feature bits (currently bits 28 through 31) are reserved for the 22 * transport being used (eg. virtio_ring), the rest are per-device feature 23 * bits. */ 24#define VIRTIO_TRANSPORT_F_START 28 25#define VIRTIO_TRANSPORT_F_END 32 26 27/* Do we get callbacks when the ring is completely used, even if we've 28 * suppressed them? */ 29#define VIRTIO_F_NOTIFY_ON_EMPTY 24 30 31#ifdef __KERNEL__ 32#include <linux/err.h> 33#include <linux/virtio.h> 34 35/** 36 * virtio_config_ops - operations for configuring a virtio device 37 * @get: read the value of a configuration field 38 * vdev: the virtio_device 39 * offset: the offset of the configuration field 40 * buf: the buffer to write the field value into. 41 * len: the length of the buffer 42 * @set: write the value of a configuration field 43 * vdev: the virtio_device 44 * offset: the offset of the configuration field 45 * buf: the buffer to read the field value from. 46 * len: the length of the buffer 47 * @get_status: read the status byte 48 * vdev: the virtio_device 49 * Returns the status byte 50 * @set_status: write the status byte 51 * vdev: the virtio_device 52 * status: the new status byte 53 * @request_vqs: request the specified number of virtqueues 54 * vdev: the virtio_device 55 * max_vqs: the max number of virtqueues we want 56 * If supplied, must call before any virtqueues are instantiated. 57 * To modify the max number of virtqueues after request_vqs has been 58 * called, call free_vqs and then request_vqs with a new value. 59 * @free_vqs: cleanup resources allocated by request_vqs 60 * vdev: the virtio_device 61 * If supplied, must call after all virtqueues have been deleted. 62 * @reset: reset the device 63 * vdev: the virtio device 64 * After this, status and feature negotiation must be done again 65 * @find_vqs: find virtqueues and instantiate them. 66 * vdev: the virtio_device 67 * nvqs: the number of virtqueues to find 68 * vqs: on success, includes new virtqueues 69 * callbacks: array of callbacks, for each virtqueue 70 * names: array of virtqueue names (mainly for debugging) 71 * Returns 0 on success or error status 72 * @del_vqs: free virtqueues found by find_vqs(). 73 * @get_features: get the array of feature bits for this device. 74 * vdev: the virtio_device 75 * Returns the first 32 feature bits (all we currently need). 76 * @finalize_features: confirm what device features we'll be using. 77 * vdev: the virtio_device 78 * This gives the final feature bits for the device: it can change 79 * the dev->feature bits if it wants. 80 */ 81typedef void vq_callback_t(struct virtqueue *); 82struct virtio_config_ops { 83 void (*get)(struct virtio_device *vdev, unsigned offset, 84 void *buf, unsigned len); 85 void (*set)(struct virtio_device *vdev, unsigned offset, 86 const void *buf, unsigned len); 87 u8 (*get_status)(struct virtio_device *vdev); 88 void (*set_status)(struct virtio_device *vdev, u8 status); 89 void (*reset)(struct virtio_device *vdev); 90 int (*find_vqs)(struct virtio_device *, unsigned nvqs, 91 struct virtqueue *vqs[], 92 vq_callback_t *callbacks[], 93 const char *names[]); 94 void (*del_vqs)(struct virtio_device *); 95 u32 (*get_features)(struct virtio_device *vdev); 96 void (*finalize_features)(struct virtio_device *vdev); 97}; 98 99/* If driver didn't advertise the feature, it will never appear. */ 100void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 101 unsigned int fbit); 102 103/** 104 * virtio_has_feature - helper to determine if this device has this feature. 105 * @vdev: the device 106 * @fbit: the feature bit 107 */ 108static inline bool virtio_has_feature(const struct virtio_device *vdev, 109 unsigned int fbit) 110{ 111 /* Did you forget to fix assumptions on max features? */ 112 MAYBE_BUILD_BUG_ON(fbit >= 32); 113 114 if (fbit < VIRTIO_TRANSPORT_F_START) 115 virtio_check_driver_offered_feature(vdev, fbit); 116 117 return test_bit(fbit, vdev->features); 118} 119 120/** 121 * virtio_config_val - look for a feature and get a virtio config entry. 122 * @vdev: the virtio device 123 * @fbit: the feature bit 124 * @offset: the type to search for. 125 * @val: a pointer to the value to fill in. 126 * 127 * The return value is -ENOENT if the feature doesn't exist. Otherwise 128 * the config value is copied into whatever is pointed to by v. */ 129#define virtio_config_val(vdev, fbit, offset, v) \ 130 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v)) 131 132static inline int virtio_config_buf(struct virtio_device *vdev, 133 unsigned int fbit, 134 unsigned int offset, 135 void *buf, unsigned len) 136{ 137 if (!virtio_has_feature(vdev, fbit)) 138 return -ENOENT; 139 140 vdev->config->get(vdev, offset, buf, len); 141 return 0; 142} 143 144static inline 145struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, 146 vq_callback_t *c, const char *n) 147{ 148 vq_callback_t *callbacks[] = { c }; 149 const char *names[] = { n }; 150 struct virtqueue *vq; 151 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names); 152 if (err < 0) 153 return ERR_PTR(err); 154 return vq; 155} 156#endif /* __KERNEL__ */ 157#endif /* _LINUX_VIRTIO_CONFIG_H */ 158