+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-/*
- * exynos-rng.c - Random Number Generator driver for the Exynos
- *
- * Copyright (c) 2017 Krzysztof Kozlowski <krzk@kernel.org>
- *
- * Loosely based on old driver from drivers/char/hw_random/exynos-rng.c:
- * Copyright (C) 2012 Samsung Electronics
- * Jonghwa Lee <jonghwa3.lee@samsung.com>
- */
-
-#include <linux/clk.h>
-#include <linux/crypto.h>
-#include <linux/err.h>
-#include <linux/io.h>
-#include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/of.h>
-#include <linux/platform_device.h>
-
-#include <crypto/internal/rng.h>
-
-#define EXYNOS_RNG_CONTROL 0x0
-#define EXYNOS_RNG_STATUS 0x10
-
-#define EXYNOS_RNG_SEED_CONF 0x14
-#define EXYNOS_RNG_GEN_PRNG BIT(1)
-
-#define EXYNOS_RNG_SEED_BASE 0x140
-#define EXYNOS_RNG_SEED(n) (EXYNOS_RNG_SEED_BASE + (n * 0x4))
-#define EXYNOS_RNG_OUT_BASE 0x160
-#define EXYNOS_RNG_OUT(n) (EXYNOS_RNG_OUT_BASE + (n * 0x4))
-
-/* EXYNOS_RNG_CONTROL bit fields */
-#define EXYNOS_RNG_CONTROL_START 0x18
-/* EXYNOS_RNG_STATUS bit fields */
-#define EXYNOS_RNG_STATUS_SEED_SETTING_DONE BIT(1)
-#define EXYNOS_RNG_STATUS_RNG_DONE BIT(5)
-
-/* Five seed and output registers, each 4 bytes */
-#define EXYNOS_RNG_SEED_REGS 5
-#define EXYNOS_RNG_SEED_SIZE (EXYNOS_RNG_SEED_REGS * 4)
-
-enum exynos_prng_type {
- EXYNOS_PRNG_UNKNOWN = 0,
- EXYNOS_PRNG_EXYNOS4,
- EXYNOS_PRNG_EXYNOS5,
-};
-
-/*
- * Driver re-seeds itself with generated random numbers to hinder
- * backtracking of the original seed.
- *
- * Time for next re-seed in ms.
- */
-#define EXYNOS_RNG_RESEED_TIME 1000
-#define EXYNOS_RNG_RESEED_BYTES 65536
-
-/*
- * In polling mode, do not wait infinitely for the engine to finish the work.
- */
-#define EXYNOS_RNG_WAIT_RETRIES 100
-
-/* Context for crypto */
-struct exynos_rng_ctx {
- struct exynos_rng_dev *rng;
-};
-
-/* Device associated memory */
-struct exynos_rng_dev {
- struct device *dev;
- enum exynos_prng_type type;
- void __iomem *mem;
- struct clk *clk;
- struct mutex lock;
- /* Generated numbers stored for seeding during resume */
- u8 seed_save[EXYNOS_RNG_SEED_SIZE];
- unsigned int seed_save_len;
- /* Time of last seeding in jiffies */
- unsigned long last_seeding;
- /* Bytes generated since last seeding */
- unsigned long bytes_seeding;
-};
-
-static struct exynos_rng_dev *exynos_rng_dev;
-
-static u32 exynos_rng_readl(struct exynos_rng_dev *rng, u32 offset)
-{
- return readl_relaxed(rng->mem + offset);
-}
-
-static void exynos_rng_writel(struct exynos_rng_dev *rng, u32 val, u32 offset)
-{
- writel_relaxed(val, rng->mem + offset);
-}
-
-static int exynos_rng_set_seed(struct exynos_rng_dev *rng,
- const u8 *seed, unsigned int slen)
-{
- u32 val;
- int i;
-
- /* Round seed length because loop iterates over full register size */
- slen = ALIGN_DOWN(slen, 4);
-
- if (slen < EXYNOS_RNG_SEED_SIZE)
- return -EINVAL;
-
- for (i = 0; i < slen ; i += 4) {
- unsigned int seed_reg = (i / 4) % EXYNOS_RNG_SEED_REGS;
-
- val = seed[i] << 24;
- val |= seed[i + 1] << 16;
- val |= seed[i + 2] << 8;
- val |= seed[i + 3] << 0;
-
- exynos_rng_writel(rng, val, EXYNOS_RNG_SEED(seed_reg));
- }
-
- val = exynos_rng_readl(rng, EXYNOS_RNG_STATUS);
- if (!(val & EXYNOS_RNG_STATUS_SEED_SETTING_DONE)) {
- dev_warn(rng->dev, "Seed setting not finished\n");
- return -EIO;
- }
-
- rng->last_seeding = jiffies;
- rng->bytes_seeding = 0;
-
- return 0;
-}
-
-/*
- * Start the engine and poll for finish. Then read from output registers
- * filling the 'dst' buffer up to 'dlen' bytes or up to size of generated
- * random data (EXYNOS_RNG_SEED_SIZE).
- *
- * On success: return 0 and store number of read bytes under 'read' address.
- * On error: return -ERRNO.
- */
-static int exynos_rng_get_random(struct exynos_rng_dev *rng,
- u8 *dst, unsigned int dlen,
- unsigned int *read)
-{
- int retry = EXYNOS_RNG_WAIT_RETRIES;
-
- if (rng->type == EXYNOS_PRNG_EXYNOS4) {
- exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START,
- EXYNOS_RNG_CONTROL);
- } else if (rng->type == EXYNOS_PRNG_EXYNOS5) {
- exynos_rng_writel(rng, EXYNOS_RNG_GEN_PRNG,
- EXYNOS_RNG_SEED_CONF);
- }
-
- while (!(exynos_rng_readl(rng,
- EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && --retry)
- cpu_relax();
-
- if (!retry)
- return -ETIMEDOUT;
-
- /* Clear status bit */
- exynos_rng_writel(rng, EXYNOS_RNG_STATUS_RNG_DONE,
- EXYNOS_RNG_STATUS);
- *read = min_t(size_t, dlen, EXYNOS_RNG_SEED_SIZE);
- memcpy_fromio(dst, rng->mem + EXYNOS_RNG_OUT_BASE, *read);
- rng->bytes_seeding += *read;
-
- return 0;
-}
-
-/* Re-seed itself from time to time */
-static void exynos_rng_reseed(struct exynos_rng_dev *rng)
-{
- unsigned long next_seeding = rng->last_seeding + \
- msecs_to_jiffies(EXYNOS_RNG_RESEED_TIME);
- unsigned long now = jiffies;
- unsigned int read = 0;
- u8 seed[EXYNOS_RNG_SEED_SIZE];
-
- if (time_before(now, next_seeding) &&
- rng->bytes_seeding < EXYNOS_RNG_RESEED_BYTES)
- return;
-
- if (exynos_rng_get_random(rng, seed, sizeof(seed), &read))
- return;
-
- exynos_rng_set_seed(rng, seed, read);
-
- /* Let others do some of their job. */
- mutex_unlock(&rng->lock);
- mutex_lock(&rng->lock);
-}
-
-static int exynos_rng_generate(struct crypto_rng *tfm,
- const u8 *src, unsigned int slen,
- u8 *dst, unsigned int dlen)
-{
- struct exynos_rng_ctx *ctx = crypto_rng_ctx(tfm);
- struct exynos_rng_dev *rng = ctx->rng;
- unsigned int read = 0;
- int ret;
-
- ret = clk_prepare_enable(rng->clk);
- if (ret)
- return ret;
-
- mutex_lock(&rng->lock);
- do {
- ret = exynos_rng_get_random(rng, dst, dlen, &read);
- if (ret)
- break;
-
- dlen -= read;
- dst += read;
-
- exynos_rng_reseed(rng);
- } while (dlen > 0);
- mutex_unlock(&rng->lock);
-
- clk_disable_unprepare(rng->clk);
-
- return ret;
-}
-
-static int exynos_rng_seed(struct crypto_rng *tfm, const u8 *seed,
- unsigned int slen)
-{
- struct exynos_rng_ctx *ctx = crypto_rng_ctx(tfm);
- struct exynos_rng_dev *rng = ctx->rng;
- int ret;
-
- ret = clk_prepare_enable(rng->clk);
- if (ret)
- return ret;
-
- mutex_lock(&rng->lock);
- ret = exynos_rng_set_seed(ctx->rng, seed, slen);
- mutex_unlock(&rng->lock);
-
- clk_disable_unprepare(rng->clk);
-
- return ret;
-}
-
-static int exynos_rng_kcapi_init(struct crypto_tfm *tfm)
-{
- struct exynos_rng_ctx *ctx = crypto_tfm_ctx(tfm);
-
- ctx->rng = exynos_rng_dev;
-
- return 0;
-}
-
-static struct rng_alg exynos_rng_alg = {
- .generate = exynos_rng_generate,
- .seed = exynos_rng_seed,
- .seedsize = EXYNOS_RNG_SEED_SIZE,
- .base = {
- .cra_name = "stdrng",
- .cra_driver_name = "exynos_rng",
- .cra_priority = 300,
- .cra_ctxsize = sizeof(struct exynos_rng_ctx),
- .cra_module = THIS_MODULE,
- .cra_init = exynos_rng_kcapi_init,
- }
-};
-
-static int exynos_rng_probe(struct platform_device *pdev)
-{
- struct exynos_rng_dev *rng;
- int ret;
-
- if (exynos_rng_dev)
- return -EEXIST;
-
- rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
- if (!rng)
- return -ENOMEM;
-
- rng->type = (uintptr_t)of_device_get_match_data(&pdev->dev);
-
- mutex_init(&rng->lock);
-
- rng->dev = &pdev->dev;
- rng->clk = devm_clk_get(&pdev->dev, "secss");
- if (IS_ERR(rng->clk)) {
- dev_err(&pdev->dev, "Couldn't get clock.\n");
- return PTR_ERR(rng->clk);
- }
-
- rng->mem = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(rng->mem))
- return PTR_ERR(rng->mem);
-
- platform_set_drvdata(pdev, rng);
-
- exynos_rng_dev = rng;
-
- ret = crypto_register_rng(&exynos_rng_alg);
- if (ret) {
- dev_err(&pdev->dev,
- "Couldn't register rng crypto alg: %d\n", ret);
- exynos_rng_dev = NULL;
- }
-
- return ret;
-}
-
-static void exynos_rng_remove(struct platform_device *pdev)
-{
- crypto_unregister_rng(&exynos_rng_alg);
-
- exynos_rng_dev = NULL;
-}
-
-static int __maybe_unused exynos_rng_suspend(struct device *dev)
-{
- struct exynos_rng_dev *rng = dev_get_drvdata(dev);
- int ret;
-
- /* If we were never seeded then after resume it will be the same */
- if (!rng->last_seeding)
- return 0;
-
- rng->seed_save_len = 0;
- ret = clk_prepare_enable(rng->clk);
- if (ret)
- return ret;
-
- mutex_lock(&rng->lock);
-
- /* Get new random numbers and store them for seeding on resume. */
- exynos_rng_get_random(rng, rng->seed_save, sizeof(rng->seed_save),
- &(rng->seed_save_len));
-
- mutex_unlock(&rng->lock);
-
- dev_dbg(rng->dev, "Stored %u bytes for seeding on system resume\n",
- rng->seed_save_len);
-
- clk_disable_unprepare(rng->clk);
-
- return 0;
-}
-
-static int __maybe_unused exynos_rng_resume(struct device *dev)
-{
- struct exynos_rng_dev *rng = dev_get_drvdata(dev);
- int ret;
-
- /* Never seeded so nothing to do */
- if (!rng->last_seeding)
- return 0;
-
- ret = clk_prepare_enable(rng->clk);
- if (ret)
- return ret;
-
- mutex_lock(&rng->lock);
-
- ret = exynos_rng_set_seed(rng, rng->seed_save, rng->seed_save_len);
-
- mutex_unlock(&rng->lock);
-
- clk_disable_unprepare(rng->clk);
-
- return ret;
-}
-
-static SIMPLE_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_suspend,
- exynos_rng_resume);
-
-static const struct of_device_id exynos_rng_dt_match[] = {
- {
- .compatible = "samsung,exynos4-rng",
- .data = (const void *)EXYNOS_PRNG_EXYNOS4,
- }, {
- .compatible = "samsung,exynos5250-prng",
- .data = (const void *)EXYNOS_PRNG_EXYNOS5,
- },
- { },
-};
-MODULE_DEVICE_TABLE(of, exynos_rng_dt_match);
-
-static struct platform_driver exynos_rng_driver = {
- .driver = {
- .name = "exynos-rng",
- .pm = &exynos_rng_pm_ops,
- .of_match_table = exynos_rng_dt_match,
- },
- .probe = exynos_rng_probe,
- .remove = exynos_rng_remove,
-};
-
-module_platform_driver(exynos_rng_driver);
-
-MODULE_DESCRIPTION("Exynos H/W Random Number Generator driver");
-MODULE_AUTHOR("Krzysztof Kozlowski <krzk@kernel.org>");
-MODULE_LICENSE("GPL v2");
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