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/*
* omap-rng.c - RNG driver for TI OMAP CPU family
*
* Author: Deepak Saxena <dsaxena@plexity.net>
*
* Copyright 2005 (c) MontaVista Software, Inc.
*
* Mostly based on original driver:
*
* Copyright (C) 2005 Nokia Corporation
* Author: Juha Yrjölä <juha.yrjola@nokia.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <asm/io.h>
#define RNG_OUT_REG 0x00 /* Output register */
#define RNG_STAT_REG 0x04 /* Status register
[0] = STAT_BUSY */
#define RNG_ALARM_REG 0x24 /* Alarm register
[7:0] = ALARM_COUNTER */
#define RNG_CONFIG_REG 0x28 /* Configuration register
[11:6] = RESET_COUNT
[5:3] = RING2_DELAY
[2:0] = RING1_DELAY */
#define RNG_REV_REG 0x3c /* Revision register
[7:0] = REV_NB */
#define RNG_MASK_REG 0x40 /* Mask and reset register
[2] = IT_EN
[1] = SOFTRESET
[0] = AUTOIDLE */
#define RNG_SYSSTATUS 0x44 /* System status
[0] = RESETDONE */
static void __iomem *rng_base;
static struct clk *rng_ick;
static struct platform_device *rng_dev;
static inline u32 omap_rng_read_reg(int reg)
{
return __raw_readl(rng_base + reg);
}
static inline void omap_rng_write_reg(int reg, u32 val)
{
__raw_writel(val, rng_base + reg);
}
static int omap_rng_data_present(struct hwrng *rng, int wait)
{
int data, i;
for (i = 0; i < 20; i++) {
data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
if (data || !wait)
break;
/* RNG produces data fast enough (2+ MBit/sec, even
* during "rngtest" loads, that these delays don't
* seem to trigger. We *could* use the RNG IRQ, but
* that'd be higher overhead ... so why bother?
*/
udelay(10);
}
return data;
}
static int omap_rng_data_read(struct hwrng *rng, u32 *data)
{
*data = omap_rng_read_reg(RNG_OUT_REG);
return 4;
}
static struct hwrng omap_rng_ops = {
.name = "omap",
.data_present = omap_rng_data_present,
.data_read = omap_rng_data_read,
};
static int __init omap_rng_probe(struct platform_device *pdev)
{
struct resource *res, *mem;
int ret;
/*
* A bit ugly, and it will never actually happen but there can
* be only one RNG and this catches any bork
*/
if (rng_dev)
return -EBUSY;
if (cpu_is_omap24xx()) {
rng_ick = clk_get(&pdev->dev, "rng_ick");
if (IS_ERR(rng_ick)) {
dev_err(&pdev->dev, "Could not get rng_ick\n");
ret = PTR_ERR(rng_ick);
return ret;
} else
clk_enable(rng_ick);
}
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
mem = request_mem_region(res->start, res->end - res->start + 1,
pdev->name);
if (mem == NULL) {
ret = -EBUSY;
goto err_region;
}
dev_set_drvdata(&pdev->dev, mem);
rng_base = ioremap(res->start, res->end - res->start + 1);
if (!rng_base) {
ret = -ENOMEM;
goto err_ioremap;
}
ret = hwrng_register(&omap_rng_ops);
if (ret)
goto err_register;
dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
omap_rng_read_reg(RNG_REV_REG));
omap_rng_write_reg(RNG_MASK_REG, 0x1);
rng_dev = pdev;
return 0;
err_register:
iounmap(rng_base);
rng_base = NULL;
err_ioremap:
release_resource(mem);
err_region:
if (cpu_is_omap24xx()) {
clk_disable(rng_ick);
clk_put(rng_ick);
}
return ret;
}
static int __exit omap_rng_remove(struct platform_device *pdev)
{
struct resource *mem = dev_get_drvdata(&pdev->dev);
hwrng_unregister(&omap_rng_ops);
omap_rng_write_reg(RNG_MASK_REG, 0x0);
iounmap(rng_base);
if (cpu_is_omap24xx()) {
clk_disable(rng_ick);
clk_put(rng_ick);
}
release_resource(mem);
rng_base = NULL;
return 0;
}
#ifdef CONFIG_PM
static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message)
{
omap_rng_write_reg(RNG_MASK_REG, 0x0);
return 0;
}
static int omap_rng_resume(struct platform_device *pdev)
{
omap_rng_write_reg(RNG_MASK_REG, 0x1);
return 0;
}
#else
#define omap_rng_suspend NULL
#define omap_rng_resume NULL
#endif
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:omap_rng");
static struct platform_driver omap_rng_driver = {
.driver = {
.name = "omap_rng",
.owner = THIS_MODULE,
},
.probe = omap_rng_probe,
.remove = __exit_p(omap_rng_remove),
.suspend = omap_rng_suspend,
.resume = omap_rng_resume
};
static int __init omap_rng_init(void)
{
if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
return -ENODEV;
return platform_driver_register(&omap_rng_driver);
}
static void __exit omap_rng_exit(void)
{
platform_driver_unregister(&omap_rng_driver);
}
module_init(omap_rng_init);
module_exit(omap_rng_exit);
MODULE_AUTHOR("Deepak Saxena (and others)");
MODULE_LICENSE("GPL");
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