From 990ab78e788093d30b9416927fafb3bc13fa086f Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Tue, 9 Jul 2019 14:29:24 +0100 Subject: rpi3: Move rng driver to drivers To allow sharing the driver between the RPi3 and RPi4, move the random number generator driver into the generic driver directory. Change-Id: Iae94d7cb22c6bce3af9bff709d76d4caf87b14d1 Signed-off-by: Andre Przywara --- drivers/rpi3/rng/rpi3_rng.c | 75 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 drivers/rpi3/rng/rpi3_rng.c (limited to 'drivers/rpi3') diff --git a/drivers/rpi3/rng/rpi3_rng.c b/drivers/rpi3/rng/rpi3_rng.c new file mode 100644 index 000000000..b6bf0052a --- /dev/null +++ b/drivers/rpi3/rng/rpi3_rng.c @@ -0,0 +1,75 @@ +/* + * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include +#include + +#include + +#include + +/* Initial amount of values to discard */ +#define RNG_WARMUP_COUNT U(0x40000) + +static void rpi3_rng_initialize(void) +{ + uint32_t int_mask, ctrl; + + /* Return if it is already enabled */ + ctrl = mmio_read_32(RPI3_RNG_BASE + RPI3_RNG_CTRL_OFFSET); + if ((ctrl & RPI3_RNG_CTRL_ENABLE) != 0U) { + return; + } + + /* Mask interrupts */ + int_mask = mmio_read_32(RPI3_RNG_BASE + RPI3_RNG_INT_MASK_OFFSET); + int_mask |= RPI3_RNG_INT_MASK_DISABLE; + mmio_write_32(RPI3_RNG_BASE + RPI3_RNG_INT_MASK_OFFSET, int_mask); + + /* Discard several values when initializing to give it time to warmup */ + mmio_write_32(RPI3_RNG_BASE + RPI3_RNG_STATUS_OFFSET, RNG_WARMUP_COUNT); + + mmio_write_32(RPI3_RNG_BASE + RPI3_RNG_CTRL_OFFSET, + RPI3_RNG_CTRL_ENABLE); +} + +static uint32_t rpi3_rng_get_word(void) +{ + size_t nwords; + + do { + /* Get number of available words to read */ + nwords = (mmio_read_32(RPI3_RNG_BASE + RPI3_RNG_STATUS_OFFSET) + >> RPI3_RNG_STATUS_NUM_WORDS_SHIFT) + & RPI3_RNG_STATUS_NUM_WORDS_MASK; + } while (nwords == 0U); + + return mmio_read_32(RPI3_RNG_BASE + RPI3_RNG_DATA_OFFSET); +} + +void rpi3_rng_read(void *buf, size_t len) +{ + uint32_t data; + size_t left = len; + uint32_t *dst = buf; + + assert(buf != NULL); + assert(len != 0U); + assert(check_uptr_overflow((uintptr_t) buf, (uintptr_t) len) == 0); + + rpi3_rng_initialize(); + + while (left >= sizeof(uint32_t)) { + data = rpi3_rng_get_word(); + *dst++ = data; + left -= sizeof(uint32_t); + } + + if (left > 0U) { + data = rpi3_rng_get_word(); + memcpy(dst, &data, left); + } +} -- cgit v1.2.1