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| 1 | +/** |
| 2 | + * Copyright (c) 2025 TOKITA Hiroshi |
| 3 | + * |
| 4 | + * SPDX-License-Identifier: Apache-2.0 |
| 5 | + */ |
| 6 | + |
| 7 | +#include <zephyr/drivers/entropy.h> |
| 8 | +#include <zephyr/virtio/virtio.h> |
| 9 | +#include <zephyr/virtio/virtqueue.h> |
| 10 | +#include <zephyr/logging/log.h> |
| 11 | + |
| 12 | +#define VIRTIO_ENTROPY_QUEUE_IDX 0 |
| 13 | + |
| 14 | +#define DT_DRV_COMPAT virtio_device4 |
| 15 | + |
| 16 | +LOG_MODULE_REGISTER(virtio_entropy, CONFIG_ENTROPY_LOG_LEVEL); |
| 17 | + |
| 18 | +struct entropy_virtio_config { |
| 19 | + const struct device *vdev; |
| 20 | +}; |
| 21 | + |
| 22 | +struct entropy_virtio_data { |
| 23 | + struct k_sem sem; |
| 24 | + uint32_t received_len; |
| 25 | +}; |
| 26 | + |
| 27 | +static void entropy_virtio_virtq_recv_cb(void *priv, uint32_t len) |
| 28 | +{ |
| 29 | + struct entropy_virtio_data *data = priv; |
| 30 | + |
| 31 | + data->received_len = len; |
| 32 | + k_sem_give(&data->sem); |
| 33 | +} |
| 34 | + |
| 35 | +static uint16_t entropy_virtio_enum_queues_cb(uint16_t q_index, uint16_t q_size_max, void *unused) |
| 36 | +{ |
| 37 | + if (q_index == VIRTIO_ENTROPY_QUEUE_IDX) { |
| 38 | + return MIN(1, q_size_max); |
| 39 | + } |
| 40 | + |
| 41 | + return 0; |
| 42 | +} |
| 43 | + |
| 44 | +static int entropy_virtio_get_entropy(const struct device *dev, uint8_t *buffer, uint16_t length) |
| 45 | +{ |
| 46 | + struct virtq_buf buf[] = {{.addr = buffer, .len = length}}; |
| 47 | + const struct entropy_virtio_config *cfg = dev->config; |
| 48 | + struct entropy_virtio_data *data = dev->data; |
| 49 | + struct virtq *vq = virtio_get_virtqueue(cfg->vdev, VIRTIO_ENTROPY_QUEUE_IDX); |
| 50 | + int ret; |
| 51 | + |
| 52 | + if (!vq) { |
| 53 | + LOG_ERR("failed to get virtqueue %d", VIRTIO_ENTROPY_QUEUE_IDX); |
| 54 | + return -ENODEV; |
| 55 | + } |
| 56 | + |
| 57 | + ret = virtq_add_buffer_chain(vq, buf, 1, 0, entropy_virtio_virtq_recv_cb, data, K_FOREVER); |
| 58 | + if (ret) { |
| 59 | + LOG_ERR("virtq_add_buffer_chain failed: %d", ret); |
| 60 | + return -EIO; |
| 61 | + } |
| 62 | + |
| 63 | + data->received_len = 0; |
| 64 | + virtio_notify_virtqueue(cfg->vdev, VIRTIO_ENTROPY_QUEUE_IDX); |
| 65 | + |
| 66 | + k_sem_take(&data->sem, K_FOREVER); |
| 67 | + |
| 68 | + if (data->received_len != length) { |
| 69 | + LOG_ERR("insufficient number of values: %d/%d", data->received_len, length); |
| 70 | + return -EIO; |
| 71 | + } |
| 72 | + |
| 73 | + return 0; |
| 74 | +} |
| 75 | + |
| 76 | +static DEVICE_API(entropy, entropy_virtio_api) = { |
| 77 | + .get_entropy = entropy_virtio_get_entropy, |
| 78 | +}; |
| 79 | + |
| 80 | +static int entropy_virtio_init(const struct device *dev) |
| 81 | +{ |
| 82 | + const struct entropy_virtio_config *cfg = dev->config; |
| 83 | + struct entropy_virtio_data *data = dev->data; |
| 84 | + int ret; |
| 85 | + |
| 86 | + ret = virtio_commit_feature_bits(cfg->vdev); |
| 87 | + if (ret != 0) { |
| 88 | + return ret; |
| 89 | + } |
| 90 | + |
| 91 | + ret = virtio_init_virtqueues(cfg->vdev, 1, entropy_virtio_enum_queues_cb, (void *)dev); |
| 92 | + if (ret) { |
| 93 | + LOG_ERR("virtio_init_virtqueues failed: %d", ret); |
| 94 | + return ret; |
| 95 | + } |
| 96 | + |
| 97 | + virtio_finalize_init(cfg->vdev); |
| 98 | + |
| 99 | + k_sem_init(&data->sem, 0, 1); |
| 100 | + |
| 101 | + LOG_DBG("VirtIO entropy driver initialized"); |
| 102 | + return 0; |
| 103 | +} |
| 104 | + |
| 105 | +#define ENTROPY_VIRTIO_INST(n) \ |
| 106 | + static struct entropy_virtio_data entropy_virtio_data_##n; \ |
| 107 | + static const struct entropy_virtio_config entropy_virtio_config_##n = { \ |
| 108 | + .vdev = DEVICE_DT_GET(DT_PARENT(DT_DRV_INST(n))), \ |
| 109 | + }; \ |
| 110 | + DEVICE_DT_INST_DEFINE(n, entropy_virtio_init, NULL, &entropy_virtio_data_##n, \ |
| 111 | + &entropy_virtio_config_##n, POST_KERNEL, \ |
| 112 | + CONFIG_ENTROPY_INIT_PRIORITY, &entropy_virtio_api); |
| 113 | + |
| 114 | +DT_INST_FOREACH_STATUS_OKAY(ENTROPY_VIRTIO_INST); |
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