forked from Minki/linux
beca35d05c
The Nomadik HW RNG driver has seen some rust and is not preparing the clock before use. Fix this up so we get rid of runtime complaints from the clock subsystem. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/*
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* Nomadik RNG support
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* Copyright 2009 Alessandro Rubini
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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/init.h>
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#include <linux/device.h>
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#include <linux/amba/bus.h>
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#include <linux/hw_random.h>
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#include <linux/io.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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static struct clk *rng_clk;
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static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
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{
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void __iomem *base = (void __iomem *)rng->priv;
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/*
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* The register is 32 bits and gives 16 random bits (low half).
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* A subsequent read will delay the core for 400ns, so we just read
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* once and accept the very unlikely very small delay, even if wait==0.
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*/
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*(u16 *)data = __raw_readl(base + 8) & 0xffff;
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return 2;
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}
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/* we have at most one RNG per machine, granted */
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static struct hwrng nmk_rng = {
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.name = "nomadik",
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.read = nmk_rng_read,
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};
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static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
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{
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void __iomem *base;
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int ret;
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rng_clk = clk_get(&dev->dev, NULL);
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if (IS_ERR(rng_clk)) {
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dev_err(&dev->dev, "could not get rng clock\n");
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ret = PTR_ERR(rng_clk);
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return ret;
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}
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clk_prepare_enable(rng_clk);
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ret = amba_request_regions(dev, dev->dev.init_name);
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if (ret)
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goto out_clk;
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ret = -ENOMEM;
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base = ioremap(dev->res.start, resource_size(&dev->res));
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if (!base)
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goto out_release;
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nmk_rng.priv = (unsigned long)base;
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ret = hwrng_register(&nmk_rng);
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if (ret)
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goto out_unmap;
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return 0;
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out_unmap:
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iounmap(base);
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out_release:
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amba_release_regions(dev);
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out_clk:
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clk_disable(rng_clk);
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clk_put(rng_clk);
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return ret;
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}
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static int nmk_rng_remove(struct amba_device *dev)
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{
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void __iomem *base = (void __iomem *)nmk_rng.priv;
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hwrng_unregister(&nmk_rng);
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iounmap(base);
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amba_release_regions(dev);
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clk_disable(rng_clk);
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clk_put(rng_clk);
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return 0;
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}
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static struct amba_id nmk_rng_ids[] = {
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{
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.id = 0x000805e1,
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.mask = 0x000fffff, /* top bits are rev and cfg: accept all */
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},
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{0, 0},
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};
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MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
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static struct amba_driver nmk_rng_driver = {
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.drv = {
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.owner = THIS_MODULE,
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.name = "rng",
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},
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.probe = nmk_rng_probe,
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.remove = nmk_rng_remove,
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.id_table = nmk_rng_ids,
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};
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module_amba_driver(nmk_rng_driver);
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MODULE_LICENSE("GPL");
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