--- /dev/null
+/*
+ * exyswd-rng.c - Random Number Generator driver for the exynos
+ *
+ * Copyright (C) 2018 Samsung Electronics
+ * Sehee Kim <sehi.kim@samsung.com>
+ *
+ * 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 <linux/hw_random.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/smc.h>
+
+#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 <sehi.kim@samsung.com>");
+MODULE_LICENSE("GPL");
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff