1 /*
2 * Copyright (c) 2023-2024 Analog Devices, Inc.
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <string.h>
8 #include <zephyr/sys/util.h>
9
10 #define DT_DRV_COMPAT adi_max32_trng
11
12 #include <zephyr/device.h>
13 #include <zephyr/drivers/entropy.h>
14 #include <zephyr/drivers/clock_control/adi_max32_clock_control.h>
15
16 #include <wrap_max32_trng.h>
17
18 struct max32_trng_config {
19 const struct device *clock;
20 struct max32_perclk perclk;
21 };
22
api_get_entropy(const struct device * dev,uint8_t * buf,uint16_t len)23 static int api_get_entropy(const struct device *dev, uint8_t *buf, uint16_t len)
24 {
25 return MXC_TRNG_Random(buf, len);
26 }
27
api_get_entropy_isr(const struct device * dev,uint8_t * buf,uint16_t len,uint32_t flags)28 static int api_get_entropy_isr(const struct device *dev, uint8_t *buf, uint16_t len, uint32_t flags)
29 {
30 int ret = 0;
31
32 if ((flags & ENTROPY_BUSYWAIT) == 0) {
33 uint32_t temp;
34 uint32_t copy_len;
35 uint32_t count = 0;
36
37 while (len) {
38 ret = Wrap_MXC_TRNG_RandomInt_NonBlocking(&temp);
39 if (ret != 0) {
40 break; /* Data not ready do not wait */
41 }
42
43 copy_len = MIN(len, 4);
44 memcpy(buf, (uint8_t *)&temp, copy_len);
45
46 len -= copy_len;
47 buf += copy_len;
48 count += copy_len;
49 }
50
51 /* User would like to read len bytes but in non-blocking mode
52 * the function might read less, in that case return value will be
53 * number of bytes read, if its 0 that means no data reads function
54 * will return -ENODATA
55 */
56 ret = count ? count : -ENODATA;
57 } else {
58 /* Allowed to busy-wait */
59 ret = api_get_entropy(dev, buf, len);
60 if (ret == 0) {
61 ret = len; /* Data retrieved successfully. */
62 }
63 }
64
65 return ret;
66 }
67
68 static DEVICE_API(entropy, entropy_max32_api) = {.get_entropy = api_get_entropy,
69 .get_entropy_isr = api_get_entropy_isr};
70
entropy_max32_init(const struct device * dev)71 static int entropy_max32_init(const struct device *dev)
72 {
73 int ret;
74 const struct max32_trng_config *cfg = dev->config;
75
76 /* Enable clock */
77 ret = clock_control_on(cfg->clock, (clock_control_subsys_t)&cfg->perclk);
78
79 return ret;
80 }
81
82 static const struct max32_trng_config max32_trng_cfg = {
83 .clock = DEVICE_DT_GET(DT_INST_CLOCKS_CTLR(0)),
84 .perclk.bus = DT_INST_CLOCKS_CELL(0, offset),
85 .perclk.bit = DT_INST_CLOCKS_CELL(0, bit),
86 };
87
88 DEVICE_DT_INST_DEFINE(0, entropy_max32_init, NULL, NULL, &max32_trng_cfg, PRE_KERNEL_1,
89 CONFIG_ENTROPY_INIT_PRIORITY, &entropy_max32_api);
90
