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