| // 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/mod_devicetable.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"); |