156 lines
3.3 KiB
C
156 lines
3.3 KiB
C
/*
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* Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/hw_random.h>
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#include <linux/platform_device.h>
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#define TRNG_CR 0x00
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#define TRNG_ISR 0x1c
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#define TRNG_ODATA 0x50
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#define TRNG_KEY 0x524e4700 /* RNG */
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struct atmel_trng {
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struct clk *clk;
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void __iomem *base;
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struct hwrng rng;
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};
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static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
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bool wait)
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{
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struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
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u32 *data = buf;
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/* data ready? */
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if (readl(trng->base + TRNG_ISR) & 1) {
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*data = readl(trng->base + TRNG_ODATA);
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/*
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ensure data ready is only set again AFTER the next data
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word is ready in case it got set between checking ISR
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and reading ODATA, so we don't risk re-reading the
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same word
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*/
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readl(trng->base + TRNG_ISR);
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return 4;
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} else
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return 0;
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}
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static int atmel_trng_probe(struct platform_device *pdev)
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{
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struct atmel_trng *trng;
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struct resource *res;
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int ret;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!res)
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return -EINVAL;
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trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
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if (!trng)
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return -ENOMEM;
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if (!devm_request_mem_region(&pdev->dev, res->start,
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resource_size(res), pdev->name))
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return -EBUSY;
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trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
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if (!trng->base)
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return -EBUSY;
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trng->clk = clk_get(&pdev->dev, NULL);
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if (IS_ERR(trng->clk))
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return PTR_ERR(trng->clk);
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ret = clk_enable(trng->clk);
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if (ret)
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goto err_enable;
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writel(TRNG_KEY | 1, trng->base + TRNG_CR);
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trng->rng.name = pdev->name;
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trng->rng.read = atmel_trng_read;
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ret = hwrng_register(&trng->rng);
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if (ret)
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goto err_register;
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platform_set_drvdata(pdev, trng);
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return 0;
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err_register:
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clk_disable(trng->clk);
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err_enable:
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clk_put(trng->clk);
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return ret;
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}
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static int atmel_trng_remove(struct platform_device *pdev)
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{
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struct atmel_trng *trng = platform_get_drvdata(pdev);
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hwrng_unregister(&trng->rng);
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writel(TRNG_KEY, trng->base + TRNG_CR);
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clk_disable(trng->clk);
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clk_put(trng->clk);
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platform_set_drvdata(pdev, NULL);
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return 0;
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}
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#ifdef CONFIG_PM
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static int atmel_trng_suspend(struct device *dev)
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{
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struct atmel_trng *trng = dev_get_drvdata(dev);
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clk_disable(trng->clk);
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return 0;
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}
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static int atmel_trng_resume(struct device *dev)
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{
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struct atmel_trng *trng = dev_get_drvdata(dev);
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return clk_enable(trng->clk);
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}
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static const struct dev_pm_ops atmel_trng_pm_ops = {
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.suspend = atmel_trng_suspend,
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.resume = atmel_trng_resume,
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};
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#endif /* CONFIG_PM */
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static struct platform_driver atmel_trng_driver = {
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.probe = atmel_trng_probe,
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.remove = atmel_trng_remove,
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.driver = {
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.name = "atmel-trng",
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.owner = THIS_MODULE,
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#ifdef CONFIG_PM
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.pm = &atmel_trng_pm_ops,
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#endif /* CONFIG_PM */
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},
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};
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module_platform_driver(atmel_trng_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
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MODULE_DESCRIPTION("Atmel true random number generator driver");
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