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 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of IBM nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. */ 28 29 /* Virtio devices use a standardized configuration space to define their 30 * features and pass configuration information, but each implementation can 31 * store and access that space differently. */ 32 #include <linux/types.h> 33 34 /* Status byte for guest to report progress, and synchronize features. */ 35 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */ 36 #define VIRTIO_CONFIG_S_ACKNOWLEDGE 1 37 /* We have found a driver for the device. */ 38 #define VIRTIO_CONFIG_S_DRIVER 2 39 /* Driver has used its parts of the config, and is happy */ 40 #define VIRTIO_CONFIG_S_DRIVER_OK 4 41 /* We've given up on this device. */ 42 #define VIRTIO_CONFIG_S_FAILED 0x80 43 44 /* Some virtio feature bits (currently bits 28 through 31) are reserved for the 45 * transport being used (eg. virtio_ring), the rest are per-device feature 46 * bits. */ 47 #define VIRTIO_TRANSPORT_F_START 28 48 #define VIRTIO_TRANSPORT_F_END 32 49 50 /* Do we get callbacks when the ring is completely used, even if we've 51 * suppressed them? */ 52 #define VIRTIO_F_NOTIFY_ON_EMPTY 24 53 54 #ifdef __KERNEL__ 55 #include <linux/err.h> 56 #include <linux/virtio.h> 57 58 /** 59 * virtio_config_ops - operations for configuring a virtio device 60 * @get: read the value of a configuration field 61 * vdev: the virtio_device 62 * offset: the offset of the configuration field 63 * buf: the buffer to write the field value into. 64 * len: the length of the buffer 65 * @set: write the value of a configuration field 66 * vdev: the virtio_device 67 * offset: the offset of the configuration field 68 * buf: the buffer to read the field value from. 69 * len: the length of the buffer 70 * @get_status: read the status byte 71 * vdev: the virtio_device 72 * Returns the status byte 73 * @set_status: write the status byte 74 * vdev: the virtio_device 75 * status: the new status byte 76 * @request_vqs: request the specified number of virtqueues 77 * vdev: the virtio_device 78 * max_vqs: the max number of virtqueues we want 79 * If supplied, must call before any virtqueues are instantiated. 80 * To modify the max number of virtqueues after request_vqs has been 81 * called, call free_vqs and then request_vqs with a new value. 82 * @free_vqs: cleanup resources allocated by request_vqs 83 * vdev: the virtio_device 84 * If supplied, must call after all virtqueues have been deleted. 85 * @reset: reset the device 86 * vdev: the virtio device 87 * After this, status and feature negotiation must be done again 88 * Device must not be reset from its vq/config callbacks, or in 89 * parallel with being added/removed. 90 * @find_vqs: find virtqueues and instantiate them. 91 * vdev: the virtio_device 92 * nvqs: the number of virtqueues to find 93 * vqs: on success, includes new virtqueues 94 * callbacks: array of callbacks, for each virtqueue 95 * names: array of virtqueue names (mainly for debugging) 96 * Returns 0 on success or error status 97 * @del_vqs: free virtqueues found by find_vqs(). 98 * @get_features: get the array of feature bits for this device. 99 * vdev: the virtio_device 100 * Returns the first 32 feature bits (all we currently need). 101 * @finalize_features: confirm what device features we'll be using. 102 * vdev: the virtio_device 103 * This gives the final feature bits for the device: it can change 104 * the dev->feature bits if it wants. 105 */ 106 typedef void vq_callback_t(struct virtqueue *); 107 struct virtio_config_ops { 108 void (*get)(struct virtio_device *vdev, unsigned offset, 109 void *buf, unsigned len); 110 void (*set)(struct virtio_device *vdev, unsigned offset, 111 const void *buf, unsigned len); 112 u8 (*get_status)(struct virtio_device *vdev); 113 void (*set_status)(struct virtio_device *vdev, u8 status); 114 void (*reset)(struct virtio_device *vdev); 115 int (*find_vqs)(struct virtio_device *, unsigned nvqs, 116 struct virtqueue *vqs[], 117 vq_callback_t *callbacks[], 118 const char *names[]); 119 void (*del_vqs)(struct virtio_device *); 120 u32 (*get_features)(struct virtio_device *vdev); 121 void (*finalize_features)(struct virtio_device *vdev); 122 }; 123 124 /* If driver didn't advertise the feature, it will never appear. */ 125 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 126 unsigned int fbit); 127 128 /** 129 * virtio_has_feature - helper to determine if this device has this feature. 130 * @vdev: the device 131 * @fbit: the feature bit 132 */ 133 static inline bool virtio_has_feature(const struct virtio_device *vdev, 134 unsigned int fbit) 135 { 136 /* Did you forget to fix assumptions on max features? */ 137 if (__builtin_constant_p(fbit)) 138 BUILD_BUG_ON(fbit >= 32); 139 else 140 BUG_ON(fbit >= 32); 141 142 if (fbit < VIRTIO_TRANSPORT_F_START) 143 virtio_check_driver_offered_feature(vdev, fbit); 144 145 return test_bit(fbit, vdev->features); 146 } 147 148 /** 149 * virtio_config_val - look for a feature and get a virtio config entry. 150 * @vdev: the virtio device 151 * @fbit: the feature bit 152 * @offset: the type to search for. 153 * @val: a pointer to the value to fill in. 154 * 155 * The return value is -ENOENT if the feature doesn't exist. Otherwise 156 * the config value is copied into whatever is pointed to by v. */ 157 #define virtio_config_val(vdev, fbit, offset, v) \ 158 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v)) 159 160 #define virtio_config_val_len(vdev, fbit, offset, v, len) \ 161 virtio_config_buf((vdev), (fbit), (offset), (v), (len)) 162 163 static inline int virtio_config_buf(struct virtio_device *vdev, 164 unsigned int fbit, 165 unsigned int offset, 166 void *buf, unsigned len) 167 { 168 if (!virtio_has_feature(vdev, fbit)) 169 return -ENOENT; 170 171 vdev->config->get(vdev, offset, buf, len); 172 return 0; 173 } 174 175 static inline 176 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, 177 vq_callback_t *c, const char *n) 178 { 179 vq_callback_t *callbacks[] = { c }; 180 const char *names[] = { n }; 181 struct virtqueue *vq; 182 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names); 183 if (err < 0) 184 return ERR_PTR(err); 185 return vq; 186 } 187 #endif /* __KERNEL__ */ 188 #endif /* _LINUX_VIRTIO_CONFIG_H */ 189