/* * exyswd-rng.c - Random Number Generator driver for the exynos * * Copyright (C) 2016 Samsung Electronics * Sehee Kim * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * */ #include #include #include #include #include #include #include #include #include #define HWRNG_RET_OK 0 #define HWRNG_RET_INVALID_ERROR 1 #define HWRNG_RET_RETRY_ERROR 2 #define HWRNG_RET_INVALID_FLAG_ERROR 3 #define HWRNG_RET_TEST_ERROR 4 #define HWRNG_RET_START_UP_TEST_DONE 5 #define HWRNG_RET_TEST_KAT_ERROR 0xC #define EXYRNG_MAX_FAILURES 25 #define EXYRNG_START_UP_SIZE (4096 + 1) #define EXYRNG_RETRY_MAX_COUNT 1000000 #define EXYRNG_START_UP_TEST_MAX_RETRY 2 uint32_t hwrng_read_flag; static struct hwrng rng; spinlock_t hwrandom_lock; #if defined(CONFIG_EXYRNG_FAIL_POLICY_DISABLE) static int hwrng_disabled; #endif static int start_up_test; #ifdef CONFIG_EXYRNG_DEBUG #define exyrng_debug(args...) printk(KERN_INFO args) #else #define exyrng_debug(args...) #endif void exynos_swd_test_fail(void) { #if defined(CONFIG_EXYRNG_FAIL_POLICY_DISABLE) hwrng_disabled = 1; printk("[ExyRNG] disabled for test failures\n"); #else /* defined(CONFIG_EXYRNG_POLICY_RESET) */ panic("[ExyRNG] It failed to health tests. It means that it detects " "the malfunction of TRNG(HW) which generates random numbers. If it " "doesn't offer enough entropy, it should not be used. The system " "reset could be a way to solve it. The health tests are designed " "to have the false positive rate of approximately once per billion " "based on min-entropy of TRNG.\n"); #endif } static int exynos_swd_startup_test(void) { uint32_t start_up_size; uint32_t retry_cnt; uint32_t test_cnt; int ret = HWRNG_RET_OK; start_up_size = EXYRNG_START_UP_SIZE; retry_cnt = 0; test_cnt = 1; while (start_up_size) { ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_GET_DATA, 1, 0); if (ret == HWRNG_RET_RETRY_ERROR) { if (retry_cnt++ > EXYRNG_RETRY_MAX_COUNT) { printk("[ExyRNG] exceed retry in start-up test\n"); break; } usleep_range(50, 100); continue; } if (ret == HWRNG_RET_TEST_ERROR || ret == HWRNG_RET_TEST_KAT_ERROR) { #ifndef CONFIG_EXYRNG_USE_CRYPTOMANAGER if (ret == HWRNG_RET_TEST_KAT_ERROR) { printk("[ExyRNG] start-up KAT test failed: %d\n", ret); } else if (test_cnt < EXYRNG_START_UP_TEST_MAX_RETRY) { start_up_size = EXYRNG_START_UP_SIZE; test_cnt++; printk("[ExyRNG] It performs start-up test " "again to detect the malfunction of TRNG with " "accuracy\n"); continue; } #endif exynos_swd_test_fail(); return -EFAULT; } /* start-up test is performed already */ if (ret == HWRNG_RET_START_UP_TEST_DONE) { ret = HWRNG_RET_OK; exyrng_debug("[ExyRNG] start-up test is already done\n"); break; } if (ret != HWRNG_RET_OK) { exyrng_debug("[ExyRNG] failed to get random\n"); return -EFAULT; } if (start_up_size >= 32) start_up_size -= 32; else start_up_size = 0; retry_cnt = 0; } return ret; } static int exynos_swd_read(struct hwrng *rng, void *data, size_t max, bool wait) { uint32_t *read_buf = data; uint32_t read_size = max; uint32_t r_data[2]; unsigned long flag; uint32_t retry_cnt; int ret = HWRNG_RET_OK; register u64 reg0 __asm__("x0"); register u64 reg1 __asm__("x1"); register u64 reg2 __asm__("x2"); register u64 reg3 __asm__("x3"); #if defined(CONFIG_EXYRNG_FAIL_POLICY_DISABLE) if (hwrng_disabled) return -EPERM; #endif reg0 = 0; reg1 = 0; reg2 = 0; reg3 = 0; retry_cnt = 0; do { spin_lock_irqsave(&hwrandom_lock, flag); if (hwrng_read_flag == 0) { ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_INIT, 0, 0); if (ret == HWRNG_RET_OK) hwrng_read_flag = 1; spin_unlock_irqrestore(&hwrandom_lock, flag); if (ret == HWRNG_RET_RETRY_ERROR) { if (retry_cnt++ > EXYRNG_RETRY_MAX_COUNT) { printk("[ExyRNG] exceed retry in init\n"); break; } usleep_range(50, 100); } else if (ret == HWRNG_RET_TEST_ERROR) { printk("[ExyRNG] health test fail after resume\n"); ret = -EAGAIN; goto out; } } else { spin_unlock_irqrestore(&hwrandom_lock, flag); break; } } while (ret == HWRNG_RET_RETRY_ERROR); if (ret != HWRNG_RET_OK) { msleep(1); return -EFAULT; } if (start_up_test) { ret = exynos_swd_startup_test(); if (ret != HWRNG_RET_OK) goto out; start_up_test = 0; printk("[ExyRNG] passed the start-up test\n"); } retry_cnt = 0; while (read_size) { spin_lock_irqsave(&hwrandom_lock, flag); ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_GET_DATA, 0, 0); __asm__ volatile( "\t" : "+r"(reg0), "+r"(reg1), "+r"(reg2), "+r"(reg3) ); r_data[0] = (uint32_t)reg2; r_data[1] = (uint32_t)reg3; spin_unlock_irqrestore(&hwrandom_lock, flag); if (ret == HWRNG_RET_RETRY_ERROR) { if (retry_cnt++ > EXYRNG_RETRY_MAX_COUNT) { ret = -EFAULT; printk("[ExyRNG] exceed retry in read\n"); goto out; } usleep_range(50, 100); continue; } if (ret == HWRNG_RET_TEST_ERROR) { exyrng_debug("[ExyRNG] failed to continuous test\n"); ret = -EAGAIN; goto out; } if (ret != HWRNG_RET_OK) { ret = -EFAULT; goto out; } *(uint32_t*)(read_buf++) = r_data[0]; *(uint32_t*)(read_buf++) = r_data[1]; read_size -= 8; retry_cnt = 0; } ret = max; out: retry_cnt = 0; do { spin_lock_irqsave(&hwrandom_lock, flag); if (!exynos_smc(SMC_CMD_RANDOM, HWRNG_EXIT, 0, 0)) { hwrng_read_flag = 0; spin_unlock_irqrestore(&hwrandom_lock, flag); break; } spin_unlock_irqrestore(&hwrandom_lock, flag); if (retry_cnt++ > EXYRNG_RETRY_MAX_COUNT) { printk("[ExyRNG] exceed retry in exit\n"); break; } usleep_range(50, 100); } while(1); return ret; } static int exyswd_rng_probe(struct platform_device *pdev) { int ret; rng.name = "exyswd_rng"; rng.read = exynos_swd_read; rng.quality = 500; spin_lock_init(&hwrandom_lock); #if defined(CONFIG_EXYRNG_FIPS_COMPLIANCE) start_up_test = 1; #endif ret = hwrng_register(&rng); if (ret) return ret; printk(KERN_INFO "ExyRNG: hwrng registered\n"); return 0; } static int exyswd_rng_remove(struct platform_device *pdev) { hwrng_unregister(&rng); return 0; } #if defined(CONFIG_PM_SLEEP) || defined(CONFIG_PM_RUNTIME) static int exyswd_rng_suspend(struct device *dev) { unsigned long flag; int ret = HWRNG_RET_OK; spin_lock_irqsave(&hwrandom_lock, flag); if (hwrng_read_flag) { ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_EXIT, 0, 0); if (ret != HWRNG_RET_OK) printk("[ExyRNG] failed to enter suspend with %d\n", ret); } spin_unlock_irqrestore(&hwrandom_lock, flag); return ret; } static int exyswd_rng_resume(struct device *dev) { unsigned long flag; int ret = HWRNG_RET_OK; spin_lock_irqsave(&hwrandom_lock, flag); #if defined(CONFIG_EXYRNG_FIPS_COMPLIANCE) ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_RESUME, 0, 0); if (ret != HWRNG_RET_OK) printk("[ExyRNG] failed to resume with %d\n", ret); #endif if (hwrng_read_flag) { ret = exynos_smc(SMC_CMD_RANDOM, HWRNG_INIT, 0, 0); if (ret != HWRNG_RET_OK) printk("[ExyRNG] failed to resume with %d\n", ret); } spin_unlock_irqrestore(&hwrandom_lock, flag); return ret; } #endif static UNIVERSAL_DEV_PM_OPS(exyswd_rng_pm_ops, exyswd_rng_suspend, exyswd_rng_resume, NULL); static struct platform_driver exyswd_rng_driver = { .probe = exyswd_rng_probe, .remove = exyswd_rng_remove, .driver = { .name = "exyswd_rng", .owner = THIS_MODULE, .pm = &exyswd_rng_pm_ops, }, }; static struct platform_device exyswd_rng_device = { .name = "exyswd_rng", .id = -1, }; static int __init exyswd_rng_init(void) { int ret; ret = platform_device_register(&exyswd_rng_device); if (ret) return ret; ret = platform_driver_register(&exyswd_rng_driver); if (ret) { platform_device_unregister(&exyswd_rng_device); return ret; } printk(KERN_INFO "ExyRNG driver, (c) 2014 Samsung Electronics\n"); return 0; } static void __exit exyswd_rng_exit(void) { platform_driver_unregister(&exyswd_rng_driver); platform_device_unregister(&exyswd_rng_device); } module_init(exyswd_rng_init); module_exit(exyswd_rng_exit); MODULE_DESCRIPTION("EXYNOS H/W Random Number Generator driver"); MODULE_AUTHOR("Sehee Kim "); MODULE_LICENSE("GPL");