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/bug.h> 57 #include <linux/virtio.h> 58 59 /** 60 * virtio_config_ops - operations for configuring a virtio device 61 * @get: read the value of a configuration field 62 * vdev: the virtio_device 63 * offset: the offset of the configuration field 64 * buf: the buffer to write the field value into. 65 * len: the length of the buffer 66 * @set: write the value of a configuration field 67 * vdev: the virtio_device 68 * offset: the offset of the configuration field 69 * buf: the buffer to read the field value from. 70 * len: the length of the buffer 71 * @get_status: read the status byte 72 * vdev: the virtio_device 73 * Returns the status byte 74 * @set_status: write the status byte 75 * vdev: the virtio_device 76 * status: the new status byte 77 * @reset: reset the device 78 * vdev: the virtio device 79 * After this, status and feature negotiation must be done again 80 * Device must not be reset from its vq/config callbacks, or in 81 * parallel with being added/removed. 82 * @find_vqs: find virtqueues and instantiate them. 83 * vdev: the virtio_device 84 * nvqs: the number of virtqueues to find 85 * vqs: on success, includes new virtqueues 86 * callbacks: array of callbacks, for each virtqueue 87 * names: array of virtqueue names (mainly for debugging) 88 * Returns 0 on success or error status 89 * @del_vqs: free virtqueues found by find_vqs(). 90 * @get_features: get the array of feature bits for this device. 91 * vdev: the virtio_device 92 * Returns the first 32 feature bits (all we currently need). 93 * @finalize_features: confirm what device features we'll be using. 94 * vdev: the virtio_device 95 * This gives the final feature bits for the device: it can change 96 * the dev->feature bits if it wants. 97 * @bus_name: return the bus name associated with the device 98 * vdev: the virtio_device 99 * This returns a pointer to the bus name a la pci_name from which 100 * the caller can then copy. 101 */ 102 typedef void vq_callback_t(struct virtqueue *); 103 struct virtio_config_ops { 104 void (*get)(struct virtio_device *vdev, unsigned offset, 105 void *buf, unsigned len); 106 void (*set)(struct virtio_device *vdev, unsigned offset, 107 const void *buf, unsigned len); 108 u8 (*get_status)(struct virtio_device *vdev); 109 void (*set_status)(struct virtio_device *vdev, u8 status); 110 void (*reset)(struct virtio_device *vdev); 111 int (*find_vqs)(struct virtio_device *, unsigned nvqs, 112 struct virtqueue *vqs[], 113 vq_callback_t *callbacks[], 114 const char *names[]); 115 void (*del_vqs)(struct virtio_device *); 116 u32 (*get_features)(struct virtio_device *vdev); 117 void (*finalize_features)(struct virtio_device *vdev); 118 const char *(*bus_name)(struct virtio_device *vdev); 119 }; 120 121 /* If driver didn't advertise the feature, it will never appear. */ 122 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 123 unsigned int fbit); 124 125 /** 126 * virtio_has_feature - helper to determine if this device has this feature. 127 * @vdev: the device 128 * @fbit: the feature bit 129 */ 130 static inline bool virtio_has_feature(const struct virtio_device *vdev, 131 unsigned int fbit) 132 { 133 /* Did you forget to fix assumptions on max features? */ 134 if (__builtin_constant_p(fbit)) 135 BUILD_BUG_ON(fbit >= 32); 136 else 137 BUG_ON(fbit >= 32); 138 139 if (fbit < VIRTIO_TRANSPORT_F_START) 140 virtio_check_driver_offered_feature(vdev, fbit); 141 142 return test_bit(fbit, vdev->features); 143 } 144 145 /** 146 * virtio_config_val - look for a feature and get a virtio config entry. 147 * @vdev: the virtio device 148 * @fbit: the feature bit 149 * @offset: the type to search for. 150 * @v: a pointer to the value to fill in. 151 * 152 * The return value is -ENOENT if the feature doesn't exist. Otherwise 153 * the config value is copied into whatever is pointed to by v. */ 154 #define virtio_config_val(vdev, fbit, offset, v) \ 155 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v)) 156 157 #define virtio_config_val_len(vdev, fbit, offset, v, len) \ 158 virtio_config_buf((vdev), (fbit), (offset), (v), (len)) 159 160 static inline int virtio_config_buf(struct virtio_device *vdev, 161 unsigned int fbit, 162 unsigned int offset, 163 void *buf, unsigned len) 164 { 165 if (!virtio_has_feature(vdev, fbit)) 166 return -ENOENT; 167 168 vdev->config->get(vdev, offset, buf, len); 169 return 0; 170 } 171 172 static inline 173 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, 174 vq_callback_t *c, const char *n) 175 { 176 vq_callback_t *callbacks[] = { c }; 177 const char *names[] = { n }; 178 struct virtqueue *vq; 179 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names); 180 if (err < 0) 181 return ERR_PTR(err); 182 return vq; 183 } 184 185 static inline 186 const char *virtio_bus_name(struct virtio_device *vdev) 187 { 188 if (!vdev->config->bus_name) 189 return "virtio"; 190 return vdev->config->bus_name(vdev); 191 } 192 193 #endif /* __KERNEL__ */ 194 #endif /* _LINUX_VIRTIO_CONFIG_H */ 195