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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/err.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/pm_runtime.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 */
/**
* struct omap_rng_private_data - RNG IP block-specific data
* @base: virtual address of the beginning of the RNG IP block registers
* @mem_res: struct resource * for the IP block registers physical memory
*/
struct omap_rng_private_data {
void __iomem *base;
struct resource *mem_res;
};
static inline u32 omap_rng_read_reg(struct omap_rng_private_data *priv, int reg)
{
return __raw_readl(priv->base + reg);
}
static inline void omap_rng_write_reg(struct omap_rng_private_data *priv,
int reg, u32 val)
{
__raw_writel(val, priv->base + reg);
}
static int omap_rng_data_present(struct hwrng *rng, int wait)
{
struct omap_rng_private_data *priv;
int data, i;
priv = (struct omap_rng_private_data *)rng->priv;
for (i = 0; i < 20; i++) {
data = omap_rng_read_reg(priv, 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)
{
struct omap_rng_private_data *priv;
priv = (struct omap_rng_private_data *)rng->priv;
*data = omap_rng_read_reg(priv, RNG_OUT_REG);
return sizeof(u32);
}
static struct hwrng omap_rng_ops = {
.name = "omap",
.data_present = omap_rng_data_present,
.data_read = omap_rng_data_read,
};
static int omap_rng_probe(struct platform_device *pdev)
{
struct omap_rng_private_data *priv;
int ret;
priv = devm_kzalloc(&pdev->dev, sizeof(struct omap_rng_private_data),
GFP_KERNEL);
if (!priv) {
dev_err(&pdev->dev, "could not allocate memory\n");
return -ENOMEM;
};
omap_rng_ops.priv = (unsigned long)priv;
platform_set_drvdata(pdev, priv);
priv->mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->base = devm_ioremap_resource(&pdev->dev, priv->mem_res);
if (IS_ERR(priv->base)) {
ret = PTR_ERR(priv->base);
goto err_ioremap;
}
pm_runtime_enable(&pdev->dev);
pm_runtime_get_sync(&pdev->dev);
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(priv, RNG_REV_REG));
omap_rng_write_reg(priv, RNG_MASK_REG, 0x1);
return 0;
err_register:
priv->base = NULL;
pm_runtime_disable(&pdev->dev);
err_ioremap:
return ret;
}
static int __exit omap_rng_remove(struct platform_device *pdev)
{
struct omap_rng_private_data *priv = platform_get_drvdata(pdev);
hwrng_unregister(&omap_rng_ops);
omap_rng_write_reg(priv, RNG_MASK_REG, 0x0);
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int omap_rng_suspend(struct device *dev)
{
struct omap_rng_private_data *priv = dev_get_drvdata(dev);
omap_rng_write_reg(priv, RNG_MASK_REG, 0x0);
pm_runtime_put_sync(dev);
return 0;
}
static int omap_rng_resume(struct device *dev)
{
struct omap_rng_private_data *priv = dev_get_drvdata(dev);
pm_runtime_get_sync(dev);
omap_rng_write_reg(priv, RNG_MASK_REG, 0x1);
return 0;
}
static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
#define OMAP_RNG_PM (&omap_rng_pm)
#else
#define OMAP_RNG_PM NULL
#endif
static struct platform_driver omap_rng_driver = {
.driver = {
.name = "omap_rng",
.owner = THIS_MODULE,
.pm = OMAP_RNG_PM,
},
.probe = omap_rng_probe,
.remove = __exit_p(omap_rng_remove),
};
module_platform_driver(omap_rng_driver);
MODULE_ALIAS("platform:omap_rng");
MODULE_AUTHOR("Deepak Saxena (and others)");
MODULE_LICENSE("GPL");
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