[net-next-2.6.git] / drivers / char / hw_random / tx4939-rng.c

/*
 * RNG driver for TX4939 Random Number Generators (RNG)
 *
 * Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/gfp.h>

#define TX4939_RNG_RCSR		0x00000000
#define TX4939_RNG_ROR(n)	(0x00000018 + (n) * 8)

#define TX4939_RNG_RCSR_INTE	0x00000008
#define TX4939_RNG_RCSR_RST	0x00000004
#define TX4939_RNG_RCSR_FIN	0x00000002
#define TX4939_RNG_RCSR_ST	0x00000001

struct tx4939_rng {
	struct hwrng rng;
	void __iomem *base;
	u64 databuf[3];
	unsigned int data_avail;
};

static void rng_io_start(void)
{
#ifndef CONFIG_64BIT
	/*
	 * readq is reading a 64-bit register using a 64-bit load.  On
	 * a 32-bit kernel however interrupts or any other processor
	 * exception would clobber the upper 32-bit of the processor
	 * register so interrupts need to be disabled.
	 */
	local_irq_disable();
#endif
}

static void rng_io_end(void)
{
#ifndef CONFIG_64BIT
	local_irq_enable();
#endif
}

static u64 read_rng(void __iomem *base, unsigned int offset)
{
	return ____raw_readq(base + offset);
}

static void write_rng(u64 val, void __iomem *base, unsigned int offset)
{
	return ____raw_writeq(val, base + offset);
}

static int tx4939_rng_data_present(struct hwrng *rng, int wait)
{
	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
	int i;

	if (rngdev->data_avail)
		return rngdev->data_avail;
	for (i = 0; i < 20; i++) {
		rng_io_start();
		if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
		      & TX4939_RNG_RCSR_ST)) {
			rngdev->databuf[0] =
				read_rng(rngdev->base, TX4939_RNG_ROR(0));
			rngdev->databuf[1] =
				read_rng(rngdev->base, TX4939_RNG_ROR(1));
			rngdev->databuf[2] =
				read_rng(rngdev->base, TX4939_RNG_ROR(2));
			rngdev->data_avail =
				sizeof(rngdev->databuf) / sizeof(u32);
			/* Start RNG */
			write_rng(TX4939_RNG_RCSR_ST,
				  rngdev->base, TX4939_RNG_RCSR);
			wait = 0;
		}
		rng_io_end();
		if (!wait)
			break;
		/* 90 bus clock cycles by default for generation */
		ndelay(90 * 5);
	}
	return rngdev->data_avail;
}

static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer)
{
	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);

	rngdev->data_avail--;
	*buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail);
	return sizeof(u32);
}

static int __init tx4939_rng_probe(struct platform_device *dev)
{
	struct tx4939_rng *rngdev;
	struct resource *r;
	int i;

	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
	if (!r)
		return -EBUSY;
	rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
	if (!rngdev)
		return -ENOMEM;
	if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
				     dev_name(&dev->dev)))
		return -EBUSY;
	rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r));
	if (!rngdev->base)
		return -EBUSY;

	rngdev->rng.name = dev_name(&dev->dev);
	rngdev->rng.data_present = tx4939_rng_data_present;
	rngdev->rng.data_read = tx4939_rng_data_read;

	rng_io_start();
	/* Reset RNG */
	write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
	write_rng(0, rngdev->base, TX4939_RNG_RCSR);
	/* Start RNG */
	write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
	rng_io_end();
	/*
	 * Drop first two results.  From the datasheet:
	 * The quality of the random numbers generated immediately
	 * after reset can be insufficient.  Therefore, do not use
	 * random numbers obtained from the first and second
	 * generations; use the ones from the third or subsequent
	 * generation.
	 */
	for (i = 0; i < 2; i++) {
		rngdev->data_avail = 0;
		if (!tx4939_rng_data_present(&rngdev->rng, 1))
			return -EIO;
	}

	platform_set_drvdata(dev, rngdev);
	return hwrng_register(&rngdev->rng);
}

static int __exit tx4939_rng_remove(struct platform_device *dev)
{
	struct tx4939_rng *rngdev = platform_get_drvdata(dev);

	hwrng_unregister(&rngdev->rng);
	platform_set_drvdata(dev, NULL);
	return 0;
}

static struct platform_driver tx4939_rng_driver = {
	.driver		= {
		.name	= "tx4939-rng",
		.owner	= THIS_MODULE,
	},
	.remove = tx4939_rng_remove,
};

static int __init tx4939rng_init(void)
{
	return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
}

static void __exit tx4939rng_exit(void)
{
	platform_driver_unregister(&tx4939_rng_driver);
}

module_init(tx4939rng_init);
module_exit(tx4939rng_exit);

MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
MODULE_LICENSE("GPL");
Commit	Line	Data
049a947c AN	1	/*
	2	* RNG driver for TX4939 Random Number Generators (RNG)
	3	*
	4	* Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
	5	*
	6	* This file is subject to the terms and conditions of the GNU General Public
	7	* License. See the file "COPYING" in the main directory of this archive
	8	* for more details.
	9	*/
	10	#include <linux/module.h>
	11	#include <linux/kernel.h>
	12	#include <linux/init.h>
	13	#include <linux/delay.h>
	14	#include <linux/io.h>
	15	#include <linux/platform_device.h>
	16	#include <linux/hw_random.h>
5a0e3ad6	17	#include <linux/gfp.h>
049a947c AN	18
	19	#define TX4939_RNG_RCSR 0x00000000
	20	#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8)
	21
	22	#define TX4939_RNG_RCSR_INTE 0x00000008
	23	#define TX4939_RNG_RCSR_RST 0x00000004
	24	#define TX4939_RNG_RCSR_FIN 0x00000002
	25	#define TX4939_RNG_RCSR_ST 0x00000001
	26
	27	struct tx4939_rng {
	28	struct hwrng rng;
	29	void __iomem *base;
	30	u64 databuf[3];
	31	unsigned int data_avail;
	32	};
	33
	34	static void rng_io_start(void)
	35	{
	36	#ifndef CONFIG_64BIT
	37	/*
	38	* readq is reading a 64-bit register using a 64-bit load. On
	39	* a 32-bit kernel however interrupts or any other processor
	40	* exception would clobber the upper 32-bit of the processor
	41	* register so interrupts need to be disabled.
	42	*/
	43	local_irq_disable();
	44	#endif
	45	}
	46
	47	static void rng_io_end(void)
	48	{
	49	#ifndef CONFIG_64BIT
	50	local_irq_enable();
	51	#endif
	52	}
	53
	54	static u64 read_rng(void __iomem *base, unsigned int offset)
	55	{
	56	return ____raw_readq(base + offset);
	57	}
	58
	59	static void write_rng(u64 val, void __iomem *base, unsigned int offset)
	60	{
	61	return ____raw_writeq(val, base + offset);
	62	}
	63
	64	static int tx4939_rng_data_present(struct hwrng *rng, int wait)
	65	{
	66	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
	67	int i;
	68
	69	if (rngdev->data_avail)
	70	return rngdev->data_avail;
	71	for (i = 0; i < 20; i++) {
	72	rng_io_start();
	73	if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
	74	& TX4939_RNG_RCSR_ST)) {
	75	rngdev->databuf[0] =
	76	read_rng(rngdev->base, TX4939_RNG_ROR(0));
	77	rngdev->databuf[1] =
	78	read_rng(rngdev->base, TX4939_RNG_ROR(1));
	79	rngdev->databuf[2] =
	80	read_rng(rngdev->base, TX4939_RNG_ROR(2));
	81	rngdev->data_avail =
82	sizeof(rngdev->databuf) / sizeof(u32);
83	/* Start RNG */
84	write_rng(TX4939_RNG_RCSR_ST,
85	rngdev->base, TX4939_RNG_RCSR);
86	wait = 0;
87	}
88	rng_io_end();
89	if (!wait)
90	break;
91	/* 90 bus clock cycles by default for generation */
92	ndelay(90 * 5);
93	}
94	return rngdev->data_avail;
95	}
96
97	static int tx4939_rng_data_read(struct hwrng rng, u32 buffer)
98	{
99	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
100
101	rngdev->data_avail--;
102	buffer = ((u32 *)&rngdev->databuf + rngdev->data_avail);
103	return sizeof(u32);
104	}
105
106	static int __init tx4939_rng_probe(struct platform_device *dev)
107	{
108	struct tx4939_rng *rngdev;
109	struct resource *r;
110	int i;
111
112	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
113	if (!r)
114	return -EBUSY;
115	rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
116	if (!rngdev)
117	return -ENOMEM;
118	if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
119	dev_name(&dev->dev)))
120	return -EBUSY;
121	rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r));
122	if (!rngdev->base)
123	return -EBUSY;
124
125	rngdev->rng.name = dev_name(&dev->dev);
126	rngdev->rng.data_present = tx4939_rng_data_present;
127	rngdev->rng.data_read = tx4939_rng_data_read;
128
129	rng_io_start();
130	/* Reset RNG */
131	write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
132	write_rng(0, rngdev->base, TX4939_RNG_RCSR);
133	/* Start RNG */
134	write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
135	rng_io_end();
136	/*
137	* Drop first two results. From the datasheet:
138	* The quality of the random numbers generated immediately
139	* after reset can be insufficient. Therefore, do not use
140	* random numbers obtained from the first and second
141	* generations; use the ones from the third or subsequent
142	* generation.
143	*/
144	for (i = 0; i < 2; i++) {
145	rngdev->data_avail = 0;
146	if (!tx4939_rng_data_present(&rngdev->rng, 1))
147	return -EIO;
148	}
149
150	platform_set_drvdata(dev, rngdev);
151	return hwrng_register(&rngdev->rng);
152	}
153
154	static int __exit tx4939_rng_remove(struct platform_device *dev)
155	{
156	struct tx4939_rng *rngdev = platform_get_drvdata(dev);
157
158	hwrng_unregister(&rngdev->rng);
159	platform_set_drvdata(dev, NULL);
160	return 0;
161	}
162
163	static struct platform_driver tx4939_rng_driver = {
164	.driver = {
165	.name = "tx4939-rng",
166	.owner = THIS_MODULE,
167	},
168	.remove = tx4939_rng_remove,
169	};
170
171	static int __init tx4939rng_init(void)
172	{
173	return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
174	}
175
176	static void __exit tx4939rng_exit(void)
177	{
178	platform_driver_unregister(&tx4939_rng_driver);
179	}
180
181	module_init(tx4939rng_init);
182	module_exit(tx4939rng_exit);
183
184	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
185	MODULE_LICENSE("GPL");