[deliverable/linux.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/err.h>
#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;

	rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
	if (!rngdev)
		return -ENOMEM;
	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
	rngdev->base = devm_ioremap_resource(&dev->dev, r);
	if (IS_ERR(rngdev->base))
		return PTR_ERR(rngdev->base);

	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 devm_hwrng_register(&dev->dev, &rngdev->rng);
}

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

module_platform_driver_probe(tx4939_rng_driver, tx4939_rng_probe);

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	*/
c7c9e1c3	10	#include <linux/err.h>
049a947c AN	11	#include <linux/module.h>
	12	#include <linux/kernel.h>
	13	#include <linux/init.h>
	14	#include <linux/delay.h>
	15	#include <linux/io.h>
	16	#include <linux/platform_device.h>
	17	#include <linux/hw_random.h>
5a0e3ad6	18	#include <linux/gfp.h>
049a947c AN	19
	20	#define TX4939_RNG_RCSR 0x00000000
	21	#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8)
	22
	23	#define TX4939_RNG_RCSR_INTE 0x00000008
	24	#define TX4939_RNG_RCSR_RST 0x00000004
	25	#define TX4939_RNG_RCSR_FIN 0x00000002
	26	#define TX4939_RNG_RCSR_ST 0x00000001
	27
	28	struct tx4939_rng {
	29	struct hwrng rng;
	30	void __iomem *base;
	31	u64 databuf[3];
	32	unsigned int data_avail;
	33	};
	34
	35	static void rng_io_start(void)
	36	{
	37	#ifndef CONFIG_64BIT
	38	/*
	39	* readq is reading a 64-bit register using a 64-bit load. On
	40	* a 32-bit kernel however interrupts or any other processor
	41	* exception would clobber the upper 32-bit of the processor
	42	* register so interrupts need to be disabled.
	43	*/
	44	local_irq_disable();
	45	#endif
	46	}
	47
	48	static void rng_io_end(void)
	49	{
	50	#ifndef CONFIG_64BIT
	51	local_irq_enable();
	52	#endif
	53	}
	54
	55	static u64 read_rng(void __iomem *base, unsigned int offset)
	56	{
	57	return ____raw_readq(base + offset);
	58	}
	59
	60	static void write_rng(u64 val, void __iomem *base, unsigned int offset)
	61	{
	62	return ____raw_writeq(val, base + offset);
	63	}
	64
	65	static int tx4939_rng_data_present(struct hwrng *rng, int wait)
	66	{
	67	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
	68	int i;
	69
	70	if (rngdev->data_avail)
	71	return rngdev->data_avail;
	72	for (i = 0; i < 20; i++) {
	73	rng_io_start();
	74	if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
	75	& TX4939_RNG_RCSR_ST)) {
	76	rngdev->databuf[0] =
	77	read_rng(rngdev->base, TX4939_RNG_ROR(0));
	78	rngdev->databuf[1] =
	79	read_rng(rngdev->base, TX4939_RNG_ROR(1));
	80	rngdev->databuf[2] =
	81	read_rng(rngdev->base, TX4939_RNG_ROR(2));
	82	rngdev->data_avail =
83	sizeof(rngdev->databuf) / sizeof(u32);
84	/* Start RNG */
85	write_rng(TX4939_RNG_RCSR_ST,
86	rngdev->base, TX4939_RNG_RCSR);
87	wait = 0;
88	}
89	rng_io_end();
90	if (!wait)
91	break;
92	/* 90 bus clock cycles by default for generation */
93	ndelay(90 * 5);
94	}
95	return rngdev->data_avail;
96	}
97
98	static int tx4939_rng_data_read(struct hwrng rng, u32 buffer)
99	{
100	struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
101
102	rngdev->data_avail--;
103	buffer = ((u32 *)&rngdev->databuf + rngdev->data_avail);
104	return sizeof(u32);
105	}
106
107	static int __init tx4939_rng_probe(struct platform_device *dev)
108	{
109	struct tx4939_rng *rngdev;
110	struct resource *r;
111	int i;
112
049a947c AN	113	rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
	114	if (!rngdev)
	115	return -ENOMEM;
9dc48034	116	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
c7c9e1c3 TR	117	rngdev->base = devm_ioremap_resource(&dev->dev, r);
	118	if (IS_ERR(rngdev->base))
	119	return PTR_ERR(rngdev->base);
049a947c AN	120
	121	rngdev->rng.name = dev_name(&dev->dev);
	122	rngdev->rng.data_present = tx4939_rng_data_present;
	123	rngdev->rng.data_read = tx4939_rng_data_read;
	124
	125	rng_io_start();
	126	/* Reset RNG */
	127	write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
	128	write_rng(0, rngdev->base, TX4939_RNG_RCSR);
	129	/* Start RNG */
	130	write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
	131	rng_io_end();
	132	/*
	133	* Drop first two results. From the datasheet:
	134	* The quality of the random numbers generated immediately
	135	* after reset can be insufficient. Therefore, do not use
	136	* random numbers obtained from the first and second
	137	* generations; use the ones from the third or subsequent
	138	* generation.
	139	*/
	140	for (i = 0; i < 2; i++) {
	141	rngdev->data_avail = 0;
	142	if (!tx4939_rng_data_present(&rngdev->rng, 1))
	143	return -EIO;
	144	}
	145
	146	platform_set_drvdata(dev, rngdev);
98a3c465	147	return devm_hwrng_register(&dev->dev, &rngdev->rng);
049a947c AN	148	}
	149
	150	static struct platform_driver tx4939_rng_driver = {
	151	.driver = {
	152	.name = "tx4939-rng",
049a947c	153	},
049a947c AN	154	};
049a947c AN	155
e7c2199f	156	module_platform_driver_probe(tx4939_rng_driver, tx4939_rng_probe);
049a947c AN	157
	158	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
	159	MODULE_LICENSE("GPL");