150 lines
3.4 KiB
C
150 lines
3.4 KiB
C
/*
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* Copyright (c) 2021 Henrik Brix Andersen <henrik@brixandersen.dk>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT neorv32_trng
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#include <zephyr/device.h>
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#include <zephyr/drivers/syscon.h>
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#include <zephyr/drivers/entropy.h>
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#include <zephyr/pm/device.h>
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#include <zephyr/sys/sys_io.h>
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#include <zephyr/logging/log.h>
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LOG_MODULE_REGISTER(neorv32_trng, CONFIG_ENTROPY_LOG_LEVEL);
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/* TRNG CTRL register bits */
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#define NEORV32_TRNG_CTRL_DATA_MASK BIT_MASK(8)
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#define NEORV32_TRNG_CTRL_EN BIT(30)
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#define NEORV32_TRNG_CTRL_VALID BIT(31)
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struct neorv32_trng_config {
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const struct device *syscon;
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mm_reg_t base;
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};
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static inline uint32_t neorv32_trng_read_ctrl(const struct device *dev)
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{
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const struct neorv32_trng_config *config = dev->config;
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return sys_read32(config->base);
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}
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static inline void neorv32_trng_write_ctrl(const struct device *dev, uint32_t ctrl)
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{
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const struct neorv32_trng_config *config = dev->config;
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sys_write32(ctrl, config->base);
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}
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static int neorv32_trng_get_entropy(const struct device *dev, uint8_t *buffer, uint16_t len)
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{
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uint32_t ctrl;
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while (len > 0) {
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ctrl = neorv32_trng_read_ctrl(dev);
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if ((ctrl & NEORV32_TRNG_CTRL_VALID) != 0) {
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*buffer++ = ctrl & NEORV32_TRNG_CTRL_DATA_MASK;
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len--;
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}
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}
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return 0;
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}
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static int neorv32_trng_get_entropy_isr(const struct device *dev, uint8_t *buffer,
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uint16_t len, uint32_t flags)
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{
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uint32_t ctrl;
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int err;
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if ((flags & ENTROPY_BUSYWAIT) == 0) {
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ctrl = neorv32_trng_read_ctrl(dev);
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if ((ctrl & NEORV32_TRNG_CTRL_VALID) != 0) {
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*buffer = ctrl & NEORV32_TRNG_CTRL_DATA_MASK;
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return 1;
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}
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/* No entropy available */
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return 0;
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}
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err = neorv32_trng_get_entropy(dev, buffer, len);
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if (err < 0) {
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return err;
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}
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return len;
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}
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static int neorv32_trng_init(const struct device *dev)
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{
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const struct neorv32_trng_config *config = dev->config;
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uint32_t features;
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int err;
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if (!device_is_ready(config->syscon)) {
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LOG_ERR("syscon device not ready");
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return -EINVAL;
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}
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err = syscon_read_reg(config->syscon, NEORV32_SYSINFO_FEATURES, &features);
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if (err < 0) {
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LOG_ERR("failed to determine implemented features (err %d)", err);
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return err;
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}
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if ((features & NEORV32_SYSINFO_FEATURES_IO_TRNG) == 0) {
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LOG_ERR("neorv32 trng not supported");
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return -ENODEV;
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}
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neorv32_trng_write_ctrl(dev, NEORV32_TRNG_CTRL_EN);
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return 0;
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}
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#ifdef CONFIG_PM_DEVICE
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static int neorv32_trng_pm_action(const struct device *dev, enum pm_device_action action)
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{
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switch (action) {
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case PM_DEVICE_ACTION_SUSPEND:
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neorv32_trng_write_ctrl(dev, 0);
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break;
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case PM_DEVICE_ACTION_RESUME:
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neorv32_trng_write_ctrl(dev, NEORV32_TRNG_CTRL_EN);
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break;
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default:
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return -ENOTSUP;
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}
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return 0;
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}
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#endif /* CONFIG_PM_DEVICE */
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static const struct entropy_driver_api neorv32_trng_driver_api = {
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.get_entropy = neorv32_trng_get_entropy,
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.get_entropy_isr = neorv32_trng_get_entropy_isr,
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};
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#define NEORV32_TRNG_INIT(n) \
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static const struct neorv32_trng_config neorv32_trng_##n##_config = { \
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.syscon = DEVICE_DT_GET(DT_INST_PHANDLE(n, syscon)), \
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.base = DT_INST_REG_ADDR(n), \
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}; \
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\
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PM_DEVICE_DT_INST_DEFINE(n, neorv32_trng_pm_action); \
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\
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DEVICE_DT_INST_DEFINE(n, &neorv32_trng_init, \
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PM_DEVICE_DT_INST_GET(n), \
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NULL, \
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&neorv32_trng_##n##_config, \
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PRE_KERNEL_1, \
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CONFIG_ENTROPY_INIT_PRIORITY, \
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&neorv32_trng_driver_api);
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DT_INST_FOREACH_STATUS_OKAY(NEORV32_TRNG_INIT)
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