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