diff options
Diffstat (limited to 'drivers/char/hw_random/exynos-trng.c')
| -rw-r--r-- | drivers/char/hw_random/exynos-trng.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c new file mode 100644 index 000000000000..1947aed7c044 --- /dev/null +++ b/drivers/char/hw_random/exynos-trng.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RNG driver for Exynos TRNGs + * + * Author: Łukasz Stelmach <l.stelmach@samsung.com> + * + * Copyright 2017 (c) Samsung Electronics Software, Inc. + * + * Based on the Exynos PRNG driver drivers/crypto/exynos-rng by + * Krzysztof Kozłowski <krzk@kernel.org> + */ + +#include <linux/clk.h> +#include <linux/crypto.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> + +#define EXYNOS_TRNG_CLKDIV (0x0) + +#define EXYNOS_TRNG_CTRL (0x20) +#define EXYNOS_TRNG_CTRL_RNGEN BIT(31) + +#define EXYNOS_TRNG_POST_CTRL (0x30) +#define EXYNOS_TRNG_ONLINE_CTRL (0x40) +#define EXYNOS_TRNG_ONLINE_STAT (0x44) +#define EXYNOS_TRNG_ONLINE_MAXCHI2 (0x48) +#define EXYNOS_TRNG_FIFO_CTRL (0x50) +#define EXYNOS_TRNG_FIFO_0 (0x80) +#define EXYNOS_TRNG_FIFO_1 (0x84) +#define EXYNOS_TRNG_FIFO_2 (0x88) +#define EXYNOS_TRNG_FIFO_3 (0x8c) +#define EXYNOS_TRNG_FIFO_4 (0x90) +#define EXYNOS_TRNG_FIFO_5 (0x94) +#define EXYNOS_TRNG_FIFO_6 (0x98) +#define EXYNOS_TRNG_FIFO_7 (0x9c) +#define EXYNOS_TRNG_FIFO_LEN (8) +#define EXYNOS_TRNG_CLOCK_RATE (500000) + + +struct exynos_trng_dev { + struct device *dev; + void __iomem *mem; + struct clk *clk; + struct hwrng rng; +}; + +static int exynos_trng_do_read(struct hwrng *rng, void *data, size_t max, + bool wait) +{ + struct exynos_trng_dev *trng; + int val; + + max = min_t(size_t, max, (EXYNOS_TRNG_FIFO_LEN * 4)); + + trng = (struct exynos_trng_dev *)rng->priv; + + writel_relaxed(max * 8, trng->mem + EXYNOS_TRNG_FIFO_CTRL); + val = readl_poll_timeout(trng->mem + EXYNOS_TRNG_FIFO_CTRL, val, + val == 0, 200, 1000000); + if (val < 0) + return val; + + memcpy_fromio(data, trng->mem + EXYNOS_TRNG_FIFO_0, max); + + return max; +} + +static int exynos_trng_init(struct hwrng *rng) +{ + struct exynos_trng_dev *trng = (struct exynos_trng_dev *)rng->priv; + unsigned long sss_rate; + u32 val; + + sss_rate = clk_get_rate(trng->clk); + + /* + * For most TRNG circuits the clock frequency of under 500 kHz + * is safe. + */ + val = sss_rate / (EXYNOS_TRNG_CLOCK_RATE * 2); + if (val > 0x7fff) { + dev_err(trng->dev, "clock divider too large: %d", val); + return -ERANGE; + } + val = val << 1; + writel_relaxed(val, trng->mem + EXYNOS_TRNG_CLKDIV); + + /* Enable the generator. */ + val = EXYNOS_TRNG_CTRL_RNGEN; + writel_relaxed(val, trng->mem + EXYNOS_TRNG_CTRL); + + /* + * Disable post-processing. /dev/hwrng is supposed to deliver + * unprocessed data. + */ + writel_relaxed(0, trng->mem + EXYNOS_TRNG_POST_CTRL); + + return 0; +} + +static int exynos_trng_probe(struct platform_device *pdev) +{ + struct exynos_trng_dev *trng; + struct resource *res; + int ret = -ENOMEM; + + trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); + if (!trng) + return ret; + + trng->rng.name = devm_kstrdup(&pdev->dev, dev_name(&pdev->dev), + GFP_KERNEL); + if (!trng->rng.name) + return ret; + + trng->rng.init = exynos_trng_init; + trng->rng.read = exynos_trng_do_read; + trng->rng.priv = (unsigned long) trng; + + platform_set_drvdata(pdev, trng); + trng->dev = &pdev->dev; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + trng->mem = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(trng->mem)) + return PTR_ERR(trng->mem); + + pm_runtime_enable(&pdev->dev); + ret = pm_runtime_get_sync(&pdev->dev); + if (ret < 0) { + dev_err(&pdev->dev, "Could not get runtime PM.\n"); + goto err_pm_get; + } + + trng->clk = devm_clk_get(&pdev->dev, "secss"); + if (IS_ERR(trng->clk)) { + ret = PTR_ERR(trng->clk); + dev_err(&pdev->dev, "Could not get clock.\n"); + goto err_clock; + } + + ret = clk_prepare_enable(trng->clk); + if (ret) { + dev_err(&pdev->dev, "Could not enable the clk.\n"); + goto err_clock; + } + + ret = hwrng_register(&trng->rng); + if (ret) { + dev_err(&pdev->dev, "Could not register hwrng device.\n"); + goto err_register; + } + + dev_info(&pdev->dev, "Exynos True Random Number Generator.\n"); + + return 0; + +err_register: + clk_disable_unprepare(trng->clk); + +err_clock: + pm_runtime_put_sync(&pdev->dev); + +err_pm_get: + pm_runtime_disable(&pdev->dev); + + return ret; +} + +static int exynos_trng_remove(struct platform_device *pdev) +{ + struct exynos_trng_dev *trng = platform_get_drvdata(pdev); + + hwrng_unregister(&trng->rng); + clk_disable_unprepare(trng->clk); + + pm_runtime_put_sync(&pdev->dev); + pm_runtime_disable(&pdev->dev); + + return 0; +} + +static int __maybe_unused exynos_trng_suspend(struct device *dev) +{ + pm_runtime_put_sync(dev); + + return 0; +} + +static int __maybe_unused exynos_trng_resume(struct device *dev) +{ + int ret; + + ret = pm_runtime_get_sync(dev); + if (ret < 0) { + dev_err(dev, "Could not get runtime PM.\n"); + pm_runtime_put_noidle(dev); + return ret; + } + + return 0; +} + +static SIMPLE_DEV_PM_OPS(exynos_trng_pm_ops, exynos_trng_suspend, + exynos_trng_resume); + +static const struct of_device_id exynos_trng_dt_match[] = { + { + .compatible = "samsung,exynos5250-trng", + }, + { }, +}; +MODULE_DEVICE_TABLE(of, exynos_trng_dt_match); + +static struct platform_driver exynos_trng_driver = { + .driver = { + .name = "exynos-trng", + .pm = &exynos_trng_pm_ops, + .of_match_table = exynos_trng_dt_match, + }, + .probe = exynos_trng_probe, + .remove = exynos_trng_remove, +}; + +module_platform_driver(exynos_trng_driver); +MODULE_AUTHOR("Łukasz Stelmach"); +MODULE_DESCRIPTION("H/W TRNG driver for Exynos chips"); +MODULE_LICENSE("GPL v2"); |