satip-axe/kernel/drivers/char/hw_random/stm-rng.c

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/*
* drivers/char/hw_random/stm-rng.c
*
* RNG driver for ST Microelectronics STx7xxx SoCs
*
* Author: Carl Shaw <carl.shaw@st.com>
*
* Copyright (c) 2007-2008 ST Microelectronics R&D Ltd.
*
* Based on omap RNG driver
*
* 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 <asm/io.h>
#define STM_RNG_STATUS_REG 0x20
#define STM_RNG_DATA_REG 0x24
static void __iomem *rng_base;
static u32 stm_rng_read_reg(int reg)
{
return __raw_readl(rng_base + reg);
}
static int stm_rng_data_present(struct hwrng *rng)
{
return ((stm_rng_read_reg(STM_RNG_STATUS_REG) & 3) == 0);
}
static int stm_rng_data_read(struct hwrng *rng, u32 *data)
{
*data = stm_rng_read_reg(STM_RNG_DATA_REG);
return 2;
}
static struct hwrng stm_rng_ops = {
.name = "stm",
.data_present = stm_rng_data_present,
.data_read = stm_rng_data_read,
};
static int __init stm_rng_probe(struct platform_device *pdev)
{
struct resource *res;
int ret;
BUG_ON(rng_base);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
printk(KERN_ERR "STM hw_random device probe failed."
"Please Check your SoC config.\n");
return -ENOENT;
}
rng_base = (u32 __iomem *)ioremap(res->start, 0x28);
if (!rng_base) {
printk(KERN_ERR "STM hw_random device: cannot ioremap\n");
return -ENOMEM;
}
ret = hwrng_register(&stm_rng_ops);
if (ret) {
iounmap(rng_base);
rng_base = NULL;
return ret;
}
dev_info(&pdev->dev, "STM Random Number Generator ver. 0.1\n");
return 0;
}
static int __exit stm_rng_remove(struct platform_device *pdev)
{
hwrng_unregister(&stm_rng_ops);
iounmap(rng_base);
rng_base = NULL;
return 0;
}
static struct platform_driver stm_rng_driver = {
.driver = {
.name = "stm-hwrandom",
.owner = THIS_MODULE,
},
.probe = stm_rng_probe,
.remove = __exit_p(stm_rng_remove),
};
static int __init stm_rng_init(void)
{
return platform_driver_register(&stm_rng_driver);
}
static void __exit stm_rng_exit(void)
{
platform_driver_unregister(&stm_rng_driver);
}
module_init(stm_rng_init);
module_exit(stm_rng_exit);
MODULE_AUTHOR("ST Microelectronics <carl.shaw@st.com>");
MODULE_LICENSE("GPL");