1 /* 2 * Copyright (c) 2024, MediaTek Inc. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <assert.h> 8 #include <stdbool.h> 9 #include <stdint.h> 10 11 #include <common/debug.h> 12 #include <drivers/delay_timer.h> 13 #include <lib/mmio.h> 14 #include <lib/smccc.h> 15 #include <plat/common/platform.h> 16 #include <platform_def.h> 17 #include <services/trng_svc.h> 18 #include <smccc_helpers.h> 19 20 #include "rng_plat.h" 21 22 static void trng_external_swrst(void) 23 { 24 /* External swrst to reset whole rng module */ 25 mmio_setbits_32(TRNG_SWRST_SET_REG, RNG_SWRST_B); 26 mmio_setbits_32(TRNG_SWRST_CLR_REG, RNG_SWRST_B); 27 28 /* Disable irq */ 29 mmio_clrbits_32(RNG_IRQ_CFG, IRQ_EN); 30 /* Set default cutoff value */ 31 mmio_write_32(RNG_HTEST, RNG_DEFAULT_CUTOFF); 32 /* Enable rng */ 33 mmio_setbits_32(RNG_EN, DRBG_EN | NRBG_EN); 34 } 35 36 static bool get_entropy_32(uint32_t *out) 37 { 38 uint64_t time = timeout_init_us(MTK_TIMEOUT_POLL); 39 int retry_times = 0; 40 41 while (!(mmio_read_32(RNG_STATUS) & DRBG_VALID)) { 42 if (mmio_read_32(RNG_STATUS) & (RNG_ERROR | APB_ERROR)) { 43 mmio_clrbits_32(RNG_EN, DRBG_EN | NRBG_EN); 44 45 mmio_clrbits_32(RNG_SWRST, SWRST_B); 46 mmio_setbits_32(RNG_SWRST, SWRST_B); 47 48 mmio_setbits_32(RNG_EN, DRBG_EN | NRBG_EN); 49 } 50 51 if (timeout_elapsed(time)) { 52 trng_external_swrst(); 53 time = timeout_init_us(MTK_TIMEOUT_POLL); 54 retry_times++; 55 } 56 57 if (retry_times > MTK_RETRY_CNT) { 58 ERROR("%s: trng NOT ready\n", __func__); 59 return false; 60 } 61 } 62 63 *out = mmio_read_32(RNG_OUT); 64 65 return true; 66 } 67 68 /* Get random number from HWRNG and return 8 bytes of entropy. 69 * Return 'true' when random value generated successfully, otherwise return 70 * 'false'. 71 */ 72 bool plat_get_entropy(uint64_t *out) 73 { 74 uint32_t seed[2] = { 0 }; 75 int i = 0; 76 77 assert(out); 78 assert(!check_uptr_overflow((uintptr_t)out, sizeof(*out))); 79 80 /* Disable interrupt mode */ 81 mmio_clrbits_32(RNG_IRQ_CFG, IRQ_EN); 82 /* Set rng health test cutoff value */ 83 mmio_write_32(RNG_HTEST, RNG_DEFAULT_CUTOFF); 84 /* Enable rng module */ 85 mmio_setbits_32(RNG_EN, DRBG_EN | NRBG_EN); 86 87 for (i = 0; i < ARRAY_SIZE(seed); i++) { 88 if (!get_entropy_32(&seed[i])) 89 return false; 90 } 91 92 /* Output 8 bytes entropy by combining 2 32-bit random numbers. */ 93 *out = ((uint64_t)seed[0] << 32) | seed[1]; 94 95 return true; 96 } 97