[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / char / hw_random / nomadik-rng.c

/*
 * Nomadik RNG support
 *  Copyright 2009 Alessandro Rubini
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/amba/bus.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>

static struct clk *rng_clk;

static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
	void __iomem *base = (void __iomem *)rng->priv;

	/*
	 * The register is 32 bits and gives 16 random bits (low half).
	 * A subsequent read will delay the core for 400ns, so we just read
	 * once and accept the very unlikely very small delay, even if wait==0.
	 */
	*(u16 *)data = __raw_readl(base + 8) & 0xffff;
	return 2;
}

/* we have at most one RNG per machine, granted */
static struct hwrng nmk_rng = {
	.name		= "nomadik",
	.read		= nmk_rng_read,
};

static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
{
	void __iomem *base;
	int ret;

	rng_clk = clk_get(&dev->dev, NULL);
	if (IS_ERR(rng_clk)) {
		dev_err(&dev->dev, "could not get rng clock\n");
		ret = PTR_ERR(rng_clk);
		return ret;
	}

	clk_enable(rng_clk);

	ret = amba_request_regions(dev, dev->dev.init_name);
	if (ret)
		goto out_clk;
	ret = -ENOMEM;
	base = ioremap(dev->res.start, resource_size(&dev->res));
	if (!base)
		goto out_release;
	nmk_rng.priv = (unsigned long)base;
	ret = hwrng_register(&nmk_rng);
	if (ret)
		goto out_unmap;
	return 0;

out_unmap:
	iounmap(base);
out_release:
	amba_release_regions(dev);
out_clk:
	clk_disable(rng_clk);
	clk_put(rng_clk);
	return ret;
}

static int nmk_rng_remove(struct amba_device *dev)
{
	void __iomem *base = (void __iomem *)nmk_rng.priv;
	hwrng_unregister(&nmk_rng);
	iounmap(base);
	amba_release_regions(dev);
	clk_disable(rng_clk);
	clk_put(rng_clk);
	return 0;
}

static struct amba_id nmk_rng_ids[] = {
	{
		.id	= 0x000805e1,
		.mask	= 0x000fffff, /* top bits are rev and cfg: accept all */
	},
	{0, 0},
};

MODULE_DEVICE_TABLE(amba, nmk_rng_ids);

static struct amba_driver nmk_rng_driver = {
	.drv = {
		.owner = THIS_MODULE,
		.name = "rng",
		},
	.probe = nmk_rng_probe,
	.remove = nmk_rng_remove,
	.id_table = nmk_rng_ids,
};

module_amba_driver(nmk_rng_driver);

MODULE_LICENSE("GPL");
Commit	Line	Data
bc85b25e AR	1	/*
	2	* Nomadik RNG support
	3	* Copyright 2009 Alessandro Rubini
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*/
	10
	11	#include <linux/kernel.h>
	12	#include <linux/module.h>
	13	#include <linux/init.h>
	14	#include <linux/device.h>
	15	#include <linux/amba/bus.h>
	16	#include <linux/hw_random.h>
	17	#include <linux/io.h>
1944cc89 SK	18	#include <linux/clk.h>
	19	#include <linux/err.h>
	20
	21	static struct clk *rng_clk;
bc85b25e AR	22
	23	static int nmk_rng_read(struct hwrng rng, void data, size_t max, bool wait)
	24	{
	25	void __iomem base = (void __iomem )rng->priv;
	26
	27	/*
	28	* The register is 32 bits and gives 16 random bits (low half).
	29	* A subsequent read will delay the core for 400ns, so we just read
	30	* once and accept the very unlikely very small delay, even if wait==0.
	31	*/
	32	(u16 )data = __raw_readl(base + 8) & 0xffff;
	33	return 2;
	34	}
	35
	36	/* we have at most one RNG per machine, granted */
	37	static struct hwrng nmk_rng = {
	38	.name = "nomadik",
	39	.read = nmk_rng_read,
	40	};
	41
aa25afad	42	static int nmk_rng_probe(struct amba_device dev, const struct amba_id id)
bc85b25e AR	43	{
	44	void __iomem *base;
	45	int ret;
	46
1944cc89 SK	47	rng_clk = clk_get(&dev->dev, NULL);
	48	if (IS_ERR(rng_clk)) {
	49	dev_err(&dev->dev, "could not get rng clock\n");
	50	ret = PTR_ERR(rng_clk);
	51	return ret;
	52	}
	53
	54	clk_enable(rng_clk);
	55
bc85b25e AR	56	ret = amba_request_regions(dev, dev->dev.init_name);
bc85b25e AR	57	if (ret)
2725ae17	58	goto out_clk;
bc85b25e AR	59	ret = -ENOMEM;
	60	base = ioremap(dev->res.start, resource_size(&dev->res));
	61	if (!base)
	62	goto out_release;
	63	nmk_rng.priv = (unsigned long)base;
	64	ret = hwrng_register(&nmk_rng);
	65	if (ret)
	66	goto out_unmap;
	67	return 0;
	68
	69	out_unmap:
	70	iounmap(base);
	71	out_release:
	72	amba_release_regions(dev);
2725ae17	73	out_clk:
1944cc89 SK	74	clk_disable(rng_clk);
1944cc89 SK	75	clk_put(rng_clk);
bc85b25e AR	76	return ret;
	77	}
	78
	79	static int nmk_rng_remove(struct amba_device *dev)
	80	{
	81	void __iomem base = (void __iomem )nmk_rng.priv;
	82	hwrng_unregister(&nmk_rng);
	83	iounmap(base);
	84	amba_release_regions(dev);
1944cc89 SK	85	clk_disable(rng_clk);
1944cc89 SK	86	clk_put(rng_clk);
bc85b25e AR	87	return 0;
	88	}
	89
	90	static struct amba_id nmk_rng_ids[] = {
	91	{
	92	.id = 0x000805e1,
	93	.mask = 0x000fffff, /* top bits are rev and cfg: accept all */
	94	},
	95	{0, 0},
	96	};
	97
4e3f3d53 DM	98	MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
4e3f3d53 DM	99
bc85b25e AR	100	static struct amba_driver nmk_rng_driver = {
	101	.drv = {
	102	.owner = THIS_MODULE,
	103	.name = "rng",
	104	},
	105	.probe = nmk_rng_probe,
	106	.remove = nmk_rng_remove,
	107	.id_table = nmk_rng_ids,
	108	};
	109
9e5ed094	110	module_amba_driver(nmk_rng_driver);
bc85b25e AR	111
bc85b25e AR	112	MODULE_LICENSE("GPL");