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/drivers/virtio.h>
9 #include <zephyr/drivers/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
entropy_virtio_virtq_recv_cb(void * priv,uint32_t len)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
entropy_virtio_enum_queues_cb(uint16_t q_index,uint16_t q_size_max,void * unused)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
entropy_virtio_get_entropy(const struct device * dev,uint8_t * buffer,uint16_t length)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 data->received_len = 0;
58 ret = virtq_add_buffer_chain(vq, buf, 1, 0, entropy_virtio_virtq_recv_cb, data, K_FOREVER);
59 if (ret) {
60 LOG_ERR("virtq_add_buffer_chain failed: %d", ret);
61 return -EIO;
62 }
63
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
entropy_virtio_init(const struct device * dev)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, NULL);
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);
115