[mirror_ubuntu-jammy-kernel.git] / drivers / char / hw_random / timeriomem-rng.c

/*
 * drivers/char/hw_random/timeriomem-rng.c
 *
 * Copyright (C) 2009 Alexander Clouter <alex@digriz.org.uk>
 *
 * Derived from drivers/char/hw_random/omap-rng.c
 *   Copyright 2005 (c) MontaVista Software, Inc.
 *   Author: Deepak Saxena <dsaxena@plexity.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Overview:
 *   This driver is useful for platforms that have an IO range that provides
 *   periodic random data from a single IO memory address.  All the platform
 *   has to do is provide the address and 'wait time' that new data becomes
 *   available.
 *
 * TODO: add support for reading sizes other than 32bits and masking
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/timeriomem-rng.h>
#include <linux/jiffies.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/completion.h>

static struct timeriomem_rng_data *timeriomem_rng_data;

static void timeriomem_rng_trigger(unsigned long);
static DEFINE_TIMER(timeriomem_rng_timer, timeriomem_rng_trigger, 0, 0);

/*
 * have data return 1, however return 0 if we have nothing
 */
static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
{
	if (rng->priv == 0)
		return 1;

	if (!wait || timeriomem_rng_data->present)
		return timeriomem_rng_data->present;

	wait_for_completion(&timeriomem_rng_data->completion);

	return 1;
}

static int timeriomem_rng_data_read(struct hwrng *rng, u32 *data)
{
	unsigned long cur;
	s32 delay;

	*data = readl(timeriomem_rng_data->address);

	if (rng->priv != 0) {
		cur = jiffies;

		delay = cur - timeriomem_rng_timer.expires;
		delay = rng->priv - (delay % rng->priv);

		timeriomem_rng_timer.expires = cur + delay;
		timeriomem_rng_data->present = 0;

		init_completion(&timeriomem_rng_data->completion);
		add_timer(&timeriomem_rng_timer);
	}

	return 4;
}

static void timeriomem_rng_trigger(unsigned long dummy)
{
	timeriomem_rng_data->present = 1;
	complete(&timeriomem_rng_data->completion);
}

static struct hwrng timeriomem_rng_ops = {
	.name		= "timeriomem",
	.data_present	= timeriomem_rng_data_present,
	.data_read	= timeriomem_rng_data_read,
	.priv		= 0,
};

static int __devinit timeriomem_rng_probe(struct platform_device *pdev)
{
	struct resource *res;
	int ret;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res)
		return -ENOENT;

	timeriomem_rng_data = pdev->dev.platform_data;

	timeriomem_rng_data->address = ioremap(res->start, resource_size(res));
	if (!timeriomem_rng_data->address)
		return -EIO;

	if (timeriomem_rng_data->period != 0
		&& usecs_to_jiffies(timeriomem_rng_data->period) > 0) {
		timeriomem_rng_timer.expires = jiffies;

		timeriomem_rng_ops.priv = usecs_to_jiffies(
						timeriomem_rng_data->period);
	}
	timeriomem_rng_data->present = 1;

	ret = hwrng_register(&timeriomem_rng_ops);
	if (ret)
		goto failed;

	dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
			timeriomem_rng_data->address,
			timeriomem_rng_data->period);

	return 0;

failed:
	dev_err(&pdev->dev, "problem registering\n");
	iounmap(timeriomem_rng_data->address);

	return ret;
}

static int __devexit timeriomem_rng_remove(struct platform_device *pdev)
{
	del_timer_sync(&timeriomem_rng_timer);
	hwrng_unregister(&timeriomem_rng_ops);

	iounmap(timeriomem_rng_data->address);

	return 0;
}

static struct platform_driver timeriomem_rng_driver = {
	.driver = {
		.name		= "timeriomem_rng",
		.owner		= THIS_MODULE,
	},
	.probe		= timeriomem_rng_probe,
	.remove		= __devexit_p(timeriomem_rng_remove),
};

static int __init timeriomem_rng_init(void)
{
	return platform_driver_register(&timeriomem_rng_driver);
}

static void __exit timeriomem_rng_exit(void)
{
	platform_driver_unregister(&timeriomem_rng_driver);
}

module_init(timeriomem_rng_init);
module_exit(timeriomem_rng_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
MODULE_DESCRIPTION("Timer IOMEM H/W RNG driver");
Commit	Line	Data
9c3c133b AC	1	/*
	2	* drivers/char/hw_random/timeriomem-rng.c
	3	*
	4	* Copyright (C) 2009 Alexander Clouter <alex@digriz.org.uk>
	5	*
	6	* Derived from drivers/char/hw_random/omap-rng.c
	7	* Copyright 2005 (c) MontaVista Software, Inc.
	8	* Author: Deepak Saxena <dsaxena@plexity.net>
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
	13	*
	14	* Overview:
	15	* This driver is useful for platforms that have an IO range that provides
	16	* periodic random data from a single IO memory address. All the platform
	17	* has to do is provide the address and 'wait time' that new data becomes
	18	* available.
	19	*
	20	* TODO: add support for reading sizes other than 32bits and masking
	21	*/
	22
	23	#include <linux/module.h>
	24	#include <linux/kernel.h>
	25	#include <linux/platform_device.h>
	26	#include <linux/hw_random.h>
	27	#include <linux/io.h>
	28	#include <linux/timeriomem-rng.h>
	29	#include <linux/jiffies.h>
	30	#include <linux/sched.h>
	31	#include <linux/timer.h>
	32	#include <linux/completion.h>
	33
	34	static struct timeriomem_rng_data *timeriomem_rng_data;
	35
	36	static void timeriomem_rng_trigger(unsigned long);
	37	static DEFINE_TIMER(timeriomem_rng_timer, timeriomem_rng_trigger, 0, 0);
	38
	39	/*
	40	* have data return 1, however return 0 if we have nothing
	41	*/
	42	static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
	43	{
	44	if (rng->priv == 0)
	45	return 1;
	46
	47	if (!wait \|\| timeriomem_rng_data->present)
	48	return timeriomem_rng_data->present;
	49
	50	wait_for_completion(&timeriomem_rng_data->completion);
	51
	52	return 1;
	53	}
	54
	55	static int timeriomem_rng_data_read(struct hwrng rng, u32 data)
	56	{
	57	unsigned long cur;
	58	s32 delay;
	59
	60	*data = readl(timeriomem_rng_data->address);
	61
	62	if (rng->priv != 0) {
	63	cur = jiffies;
	64
65	delay = cur - timeriomem_rng_timer.expires;
66	delay = rng->priv - (delay % rng->priv);
67
68	timeriomem_rng_timer.expires = cur + delay;
69	timeriomem_rng_data->present = 0;
70
71	init_completion(&timeriomem_rng_data->completion);
72	add_timer(&timeriomem_rng_timer);
73	}
74
75	return 4;
76	}
77
78	static void timeriomem_rng_trigger(unsigned long dummy)
79	{
80	timeriomem_rng_data->present = 1;
81	complete(&timeriomem_rng_data->completion);
82	}
83
84	static struct hwrng timeriomem_rng_ops = {
85	.name = "timeriomem",
86	.data_present = timeriomem_rng_data_present,
87	.data_read = timeriomem_rng_data_read,
88	.priv = 0,
89	};
90
08ced854	91	static int __devinit timeriomem_rng_probe(struct platform_device *pdev)
9c3c133b	92	{
08ced854	93	struct resource *res;
9c3c133b AC	94	int ret;
9c3c133b AC	95
3341323b AC	96	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	97
	98	if (!res)
	99	return -ENOENT;
	100
9c3c133b AC	101	timeriomem_rng_data = pdev->dev.platform_data;
9c3c133b AC	102
033590fc	103	timeriomem_rng_data->address = ioremap(res->start, resource_size(res));
08ced854 AC	104	if (!timeriomem_rng_data->address)
08ced854 AC	105	return -EIO;
3341323b	106
9c3c133b AC	107	if (timeriomem_rng_data->period != 0
	108	&& usecs_to_jiffies(timeriomem_rng_data->period) > 0) {
	109	timeriomem_rng_timer.expires = jiffies;
	110
	111	timeriomem_rng_ops.priv = usecs_to_jiffies(
	112	timeriomem_rng_data->period);
	113	}
	114	timeriomem_rng_data->present = 1;
	115
	116	ret = hwrng_register(&timeriomem_rng_ops);
3341323b	117	if (ret)
08ced854	118	goto failed;
9c3c133b AC	119
	120	dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
	121	timeriomem_rng_data->address,
	122	timeriomem_rng_data->period);
	123
	124	return 0;
3341323b	125
08ced854	126	failed:
3341323b AC	127	dev_err(&pdev->dev, "problem registering\n");
3341323b AC	128	iounmap(timeriomem_rng_data->address);
3341323b AC	129
3341323b AC	130	return ret;
9c3c133b AC	131	}
	132
	133	static int __devexit timeriomem_rng_remove(struct platform_device *pdev)
	134	{
	135	del_timer_sync(&timeriomem_rng_timer);
	136	hwrng_unregister(&timeriomem_rng_ops);
	137
3341323b	138	iounmap(timeriomem_rng_data->address);
3341323b	139
9c3c133b AC	140	return 0;
	141	}
	142
	143	static struct platform_driver timeriomem_rng_driver = {
	144	.driver = {
	145	.name = "timeriomem_rng",
	146	.owner = THIS_MODULE,
	147	},
	148	.probe = timeriomem_rng_probe,
	149	.remove = __devexit_p(timeriomem_rng_remove),
	150	};
	151
	152	static int __init timeriomem_rng_init(void)
	153	{
	154	return platform_driver_register(&timeriomem_rng_driver);
	155	}
	156
	157	static void __exit timeriomem_rng_exit(void)
	158	{
	159	platform_driver_unregister(&timeriomem_rng_driver);
	160	}
	161
	162	module_init(timeriomem_rng_init);
	163	module_exit(timeriomem_rng_exit);
	164
	165	MODULE_LICENSE("GPL");
	166	MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
	167	MODULE_DESCRIPTION("Timer IOMEM H/W RNG driver");