| /* |
| * Copyright (c) 2019 Antmicro <www.antmicro.com> |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #define DT_DRV_COMPAT litex_prbs |
| |
| #include <device.h> |
| #include <drivers/entropy.h> |
| #include <errno.h> |
| #include <init.h> |
| #include <soc.h> |
| #include <string.h> |
| #include <zephyr.h> |
| |
| #define PRBS_STATUS ((volatile uint32_t *)DT_INST_REG_ADDR(0)) |
| #define PRBS_WIDTH DT_INST_REG_SIZE(0) |
| #define SUBREG_SIZE_BIT 8 |
| |
| static inline unsigned int prbs_read(volatile uint32_t *reg_status, |
| volatile uint32_t reg_width) |
| { |
| uint32_t shifted_data, shift, i; |
| uint32_t result = 0; |
| |
| for (i = 0; i < reg_width; ++i) { |
| shifted_data = *(reg_status + i); |
| shift = (reg_width - i - 1) * SUBREG_SIZE_BIT; |
| result |= (shifted_data << shift); |
| } |
| |
| return result; |
| } |
| |
| static int entropy_prbs_get_entropy(const struct device *dev, uint8_t *buffer, |
| uint16_t length) |
| { |
| while (length > 0) { |
| size_t to_copy; |
| uint32_t value; |
| |
| value = prbs_read(PRBS_STATUS, PRBS_WIDTH); |
| to_copy = MIN(length, sizeof(value)); |
| |
| memcpy(buffer, &value, to_copy); |
| buffer += to_copy; |
| length -= to_copy; |
| } |
| return 0; |
| } |
| |
| static int entropy_prbs_init(const struct device *dev) |
| { |
| return 0; |
| } |
| |
| static const struct entropy_driver_api entropy_prbs_api = { |
| .get_entropy = entropy_prbs_get_entropy |
| }; |
| |
| DEVICE_DT_INST_DEFINE(0, |
| entropy_prbs_init, NULL, NULL, NULL, |
| PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE, |
| &entropy_prbs_api); |