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 * @find_vqs: find virtqueues and instantiate them. 89 * vdev: the virtio_device 90 * nvqs: the number of virtqueues to find 91 * vqs: on success, includes new virtqueues 92 * callbacks: array of callbacks, for each virtqueue 93 * names: array of virtqueue names (mainly for debugging) 94 * Returns 0 on success or error status 95 * @del_vqs: free virtqueues found by find_vqs(). 96 * @get_features: get the array of feature bits for this device. 97 * vdev: the virtio_device 98 * Returns the first 32 feature bits (all we currently need). 99 * @finalize_features: confirm what device features we'll be using. 100 * vdev: the virtio_device 101 * This gives the final feature bits for the device: it can change 102 * the dev->feature bits if it wants. 103 */ 104 typedef void vq_callback_t(struct virtqueue *); 105 struct virtio_config_ops { 106 void (*get)(struct virtio_device *vdev, unsigned offset, 107 void *buf, unsigned len); 108 void (*set)(struct virtio_device *vdev, unsigned offset, 109 const void *buf, unsigned len); 110 u8 (*get_status)(struct virtio_device *vdev); 111 void (*set_status)(struct virtio_device *vdev, u8 status); 112 void (*reset)(struct virtio_device *vdev); 113 int (*find_vqs)(struct virtio_device *, unsigned nvqs, 114 struct virtqueue *vqs[], 115 vq_callback_t *callbacks[], 116 const char *names[]); 117 void (*del_vqs)(struct virtio_device *); 118 u32 (*get_features)(struct virtio_device *vdev); 119 void (*finalize_features)(struct virtio_device *vdev); 120 }; 121 122 /* If driver didn't advertise the feature, it will never appear. */ 123 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 124 unsigned int fbit); 125 126 /** 127 * virtio_has_feature - helper to determine if this device has this feature. 128 * @vdev: the device 129 * @fbit: the feature bit 130 */ 131 static inline bool virtio_has_feature(const struct virtio_device *vdev, 132 unsigned int fbit) 133 { 134 /* Did you forget to fix assumptions on max features? */ 135 if (__builtin_constant_p(fbit)) 136 BUILD_BUG_ON(fbit >= 32); 137 else 138 BUG_ON(fbit >= 32); 139 140 if (fbit < VIRTIO_TRANSPORT_F_START) 141 virtio_check_driver_offered_feature(vdev, fbit); 142 143 return test_bit(fbit, vdev->features); 144 } 145 146 /** 147 * virtio_config_val - look for a feature and get a virtio config entry. 148 * @vdev: the virtio device 149 * @fbit: the feature bit 150 * @offset: the type to search for. 151 * @val: a pointer to the value to fill in. 152 * 153 * The return value is -ENOENT if the feature doesn't exist. Otherwise 154 * the config value is copied into whatever is pointed to by v. */ 155 #define virtio_config_val(vdev, fbit, offset, v) \ 156 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v)) 157 158 static inline int virtio_config_buf(struct virtio_device *vdev, 159 unsigned int fbit, 160 unsigned int offset, 161 void *buf, unsigned len) 162 { 163 if (!virtio_has_feature(vdev, fbit)) 164 return -ENOENT; 165 166 vdev->config->get(vdev, offset, buf, len); 167 return 0; 168 } 169 170 static inline 171 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, 172 vq_callback_t *c, const char *n) 173 { 174 vq_callback_t *callbacks[] = { c }; 175 const char *names[] = { n }; 176 struct virtqueue *vq; 177 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names); 178 if (err < 0) 179 return ERR_PTR(err); 180 return vq; 181 } 182 #endif /* __KERNEL__ */ 183 #endif /* _LINUX_VIRTIO_CONFIG_H */ 184