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/*
* exynos-rng.c - Random Number Generator driver for the exynos
*
* Copyright (C) 2012 Samsung Electronics
* Jonghwa Lee <jonghwa3.lee@smasung.com>
*
* 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;
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/hw_random.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/pm_runtime.h>
#include <linux/err.h>
#define EXYNOS_PRNG_STATUS_OFFSET 0x10
#define EXYNOS_PRNG_SEED_OFFSET 0x140
#define EXYNOS_PRNG_OUT1_OFFSET 0x160
#define SEED_SETTING_DONE BIT(1)
#define PRNG_START 0x18
#define PRNG_DONE BIT(5)
#define EXYNOS_AUTOSUSPEND_DELAY 100
struct exynos_rng {
struct device *dev;
struct hwrng rng;
void __iomem *mem;
struct clk *clk;
};
static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset)
{
return __raw_readl(rng->mem + offset);
}
static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset)
{
__raw_writel(val, rng->mem + offset);
}
static int exynos_init(struct hwrng *rng)
{
struct exynos_rng *exynos_rng = container_of(rng,
struct exynos_rng, rng);
int i;
int ret = 0;
pm_runtime_get_sync(exynos_rng->dev);
for (i = 0 ; i < 5 ; i++)
exynos_rng_writel(exynos_rng, jiffies,
EXYNOS_PRNG_SEED_OFFSET + 4*i);
if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
& SEED_SETTING_DONE))
ret = -EIO;
pm_runtime_put_noidle(exynos_rng->dev);
return ret;
}
static int exynos_read(struct hwrng *rng, void *buf,
size_t max, bool wait)
{
struct exynos_rng *exynos_rng = container_of(rng,
struct exynos_rng, rng);
u32 *data = buf;
pm_runtime_get_sync(exynos_rng->dev);
exynos_rng_writel(exynos_rng, PRNG_START, 0);
while (!(exynos_rng_readl(exynos_rng,
EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE))
cpu_relax();
exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
*data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
pm_runtime_mark_last_busy(exynos_rng->dev);
pm_runtime_autosuspend(exynos_rng->dev);
return 4;
}
static int exynos_rng_probe(struct platform_device *pdev)
{
struct exynos_rng *exynos_rng;
exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
GFP_KERNEL);
if (!exynos_rng)
return -ENOMEM;
exynos_rng->dev = &pdev->dev;
exynos_rng->rng.name = "exynos";
exynos_rng->rng.init = exynos_init;
exynos_rng->rng.read = exynos_read;
exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
if (IS_ERR(exynos_rng->clk)) {
dev_err(&pdev->dev, "Couldn't get clock.\n");
return -ENOENT;
}
exynos_rng->mem = devm_request_and_ioremap(&pdev->dev,
platform_get_resource(pdev, IORESOURCE_MEM, 0));
if (!exynos_rng->mem)
return -EBUSY;
platform_set_drvdata(pdev, exynos_rng);
pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_enable(&pdev->dev);
return hwrng_register(&exynos_rng->rng);
}
static int exynos_rng_remove(struct platform_device *pdev)
{
struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
hwrng_unregister(&exynos_rng->rng);
return 0;
}
static int exynos_rng_runtime_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
clk_disable_unprepare(exynos_rng->clk);
return 0;
}
static int exynos_rng_runtime_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
return clk_prepare_enable(exynos_rng->clk);
}
UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend,
exynos_rng_runtime_resume, NULL);
static struct platform_driver exynos_rng_driver = {
.driver = {
.name = "exynos-rng",
.owner = THIS_MODULE,
.pm = &exynos_rng_pm_ops,
},
.probe = exynos_rng_probe,
.remove = exynos_rng_remove,
};
module_platform_driver(exynos_rng_driver);
MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
MODULE_LICENSE("GPL");
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