112 lines
2.6 KiB
C
112 lines
2.6 KiB
C
/**
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* Copyright (c) 2010-2012 Broadcom. All rights reserved.
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* Copyright (c) 2013 Lubomir Rintel
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License ("GPL")
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* version 2, as published by the Free Software Foundation.
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*/
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#include <linux/hw_random.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/of_platform.h>
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#include <linux/platform_device.h>
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#include <linux/printk.h>
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#define RNG_CTRL 0x0
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#define RNG_STATUS 0x4
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#define RNG_DATA 0x8
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/* enable rng */
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#define RNG_RBGEN 0x1
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/* the initial numbers generated are "less random" so will be discarded */
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#define RNG_WARMUP_COUNT 0x40000
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static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
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bool wait)
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{
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void __iomem *rng_base = (void __iomem *)rng->priv;
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while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) {
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if (!wait)
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return 0;
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cpu_relax();
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}
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*(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
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return sizeof(u32);
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}
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static struct hwrng bcm2835_rng_ops = {
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.name = "bcm2835",
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.read = bcm2835_rng_read,
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};
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static int bcm2835_rng_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->of_node;
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void __iomem *rng_base;
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int err;
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/* map peripheral */
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rng_base = of_iomap(np, 0);
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if (!rng_base) {
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dev_err(dev, "failed to remap rng regs");
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return -ENODEV;
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}
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bcm2835_rng_ops.priv = (unsigned long)rng_base;
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/* set warm-up count & enable */
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__raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
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__raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
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/* register driver */
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err = hwrng_register(&bcm2835_rng_ops);
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if (err) {
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dev_err(dev, "hwrng registration failed\n");
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iounmap(rng_base);
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} else
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dev_info(dev, "hwrng registered\n");
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return err;
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}
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static int bcm2835_rng_remove(struct platform_device *pdev)
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{
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void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv;
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/* disable rng hardware */
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__raw_writel(0, rng_base + RNG_CTRL);
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/* unregister driver */
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hwrng_unregister(&bcm2835_rng_ops);
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iounmap(rng_base);
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return 0;
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}
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static const struct of_device_id bcm2835_rng_of_match[] = {
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{ .compatible = "brcm,bcm2835-rng", },
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{},
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};
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MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
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static struct platform_driver bcm2835_rng_driver = {
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.driver = {
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.name = "bcm2835-rng",
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.of_match_table = bcm2835_rng_of_match,
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},
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.probe = bcm2835_rng_probe,
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.remove = bcm2835_rng_remove,
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};
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module_platform_driver(bcm2835_rng_driver);
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MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
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MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");
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MODULE_LICENSE("GPL v2");
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