| // Copyright 2018 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef GARNET_BIN_GUEST_VMM_DEVICE_CONFIG_H_ |
| #define GARNET_BIN_GUEST_VMM_DEVICE_CONFIG_H_ |
| |
| #include <zircon/types.h> |
| |
| static constexpr zx_signals_t kDeviceInterruptShift = |
| __builtin_ctz(ZX_USER_SIGNAL_ALL); |
| |
| // Virtio 1.0 Section 4.1.4.4: notify_off_multiplier is combined with the |
| // queue_notify_off to derive the Queue Notify address within a BAR for a |
| // virtqueue: |
| // |
| // cap.offset + queue_notify_off * notify_off_multiplier |
| // |
| // Virtio 1.0 Section 4.1.4.4.1: The device MUST either present |
| // notify_off_multiplier as an even power of 2, or present |
| // notify_off_multiplier as 0. |
| // |
| // By using a multiplier of 4, we use sequential 4b words to notify, ex: |
| // |
| // cap.offset + 0 -> Notify Queue 0 |
| // cap.offset + 4 -> Notify Queue 1 |
| // ... |
| // cap.offset + 4n -> Notify Queue n |
| static constexpr size_t kQueueNotifyMultiplier = 4; |
| |
| constexpr uint16_t queue_from(zx_gpaddr_t base, zx_gpaddr_t off) { |
| return (off - base) / kQueueNotifyMultiplier; |
| } |
| |
| #endif // GARNET_BIN_GUEST_VMM_DEVICE_CONFIG_H_ |
