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/*
* RNG driver for Freescale RNGA
*
* Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
* Author: Alan Carvalho de Assis <acassis@gmail.com>
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*
* This driver is based on other RNG drivers.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/io.h>
/* RNGA Registers */
#define RNGA_CONTROL 0x00
#define RNGA_STATUS 0x04
#define RNGA_ENTROPY 0x08
#define RNGA_OUTPUT_FIFO 0x0c
#define RNGA_MODE 0x10
#define RNGA_VERIFICATION_CONTROL 0x14
#define RNGA_OSC_CONTROL_COUNTER 0x18
#define RNGA_OSC1_COUNTER 0x1c
#define RNGA_OSC2_COUNTER 0x20
#define RNGA_OSC_COUNTER_STATUS 0x24
/* RNGA Registers Range */
#define RNG_ADDR_RANGE 0x28
/* RNGA Control Register */
#define RNGA_CONTROL_SLEEP 0x00000010
#define RNGA_CONTROL_CLEAR_INT 0x00000008
#define RNGA_CONTROL_MASK_INTS 0x00000004
#define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002
#define RNGA_CONTROL_GO 0x00000001
#define RNGA_STATUS_LEVEL_MASK 0x0000ff00
/* RNGA Status Register */
#define RNGA_STATUS_OSC_DEAD 0x80000000
#define RNGA_STATUS_SLEEP 0x00000010
#define RNGA_STATUS_ERROR_INT 0x00000008
#define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004
#define RNGA_STATUS_LAST_READ_STATUS 0x00000002
#define RNGA_STATUS_SECURITY_VIOLATION 0x00000001
static struct platform_device *rng_dev;
static int mxc_rnga_data_present(struct hwrng *rng)
{
int level;
void __iomem *rng_base = (void __iomem *)rng->priv;
/* how many random numbers is in FIFO? [0-16] */
level = ((__raw_readl(rng_base + RNGA_STATUS) &
RNGA_STATUS_LEVEL_MASK) >> 8);
return level > 0 ? 1 : 0;
}
static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
{
int err;
u32 ctrl;
void __iomem *rng_base = (void __iomem *)rng->priv;
/* retrieve a random number from FIFO */
*data = __raw_readl(rng_base + RNGA_OUTPUT_FIFO);
/* some error while reading this random number? */
err = __raw_readl(rng_base + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
/* if error: clear error interrupt, but doesn't return random number */
if (err) {
dev_dbg(&rng_dev->dev, "Error while reading random number!\n");
ctrl = __raw_readl(rng_base + RNGA_CONTROL);
__raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
rng_base + RNGA_CONTROL);
return 0;
} else
return 4;
}
static int mxc_rnga_init(struct hwrng *rng)
{
u32 ctrl, osc;
void __iomem *rng_base = (void __iomem *)rng->priv;
/* wake up */
ctrl = __raw_readl(rng_base + RNGA_CONTROL);
__raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, rng_base + RNGA_CONTROL);
/* verify if oscillator is working */
osc = __raw_readl(rng_base + RNGA_STATUS);
if (osc & RNGA_STATUS_OSC_DEAD) {
dev_err(&rng_dev->dev, "RNGA Oscillator is dead!\n");
return -ENODEV;
}
/* go running */
ctrl = __raw_readl(rng_base + RNGA_CONTROL);
__raw_writel(ctrl | RNGA_CONTROL_GO, rng_base + RNGA_CONTROL);
return 0;
}
static void mxc_rnga_cleanup(struct hwrng *rng)
{
u32 ctrl;
void __iomem *rng_base = (void __iomem *)rng->priv;
ctrl = __raw_readl(rng_base + RNGA_CONTROL);
/* stop rnga */
__raw_writel(ctrl & ~RNGA_CONTROL_GO, rng_base + RNGA_CONTROL);
}
static struct hwrng mxc_rnga = {
.name = "mxc-rnga",
.init = mxc_rnga_init,
.cleanup = mxc_rnga_cleanup,
.data_present = mxc_rnga_data_present,
.data_read = mxc_rnga_data_read
};
static int __init mxc_rnga_probe(struct platform_device *pdev)
{
int err = -ENODEV;
struct clk *clk;
struct resource *res, *mem;
void __iomem *rng_base = NULL;
if (rng_dev)
return -EBUSY;
clk = clk_get(&pdev->dev, "rng");
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "Could not get rng_clk!\n");
err = PTR_ERR(clk);
goto out;
}
clk_enable(clk);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
err = -ENOENT;
goto err_region;
}
mem = request_mem_region(res->start, resource_size(res), pdev->name);
if (mem == NULL) {
err = -EBUSY;
goto err_region;
}
rng_base = ioremap(res->start, resource_size(res));
if (!rng_base) {
err = -ENOMEM;
goto err_ioremap;
}
mxc_rnga.priv = (unsigned long)rng_base;
err = hwrng_register(&mxc_rnga);
if (err) {
dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
goto err_register;
}
rng_dev = pdev;
dev_info(&pdev->dev, "MXC RNGA Registered.\n");
return 0;
err_register:
iounmap(rng_base);
rng_base = NULL;
err_ioremap:
release_mem_region(res->start, resource_size(res));
err_region:
clk_disable(clk);
clk_put(clk);
out:
return err;
}
static int __exit mxc_rnga_remove(struct platform_device *pdev)
{
struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
void __iomem *rng_base = (void __iomem *)mxc_rnga.priv;
struct clk *clk = clk_get(&pdev->dev, "rng");
hwrng_unregister(&mxc_rnga);
iounmap(rng_base);
release_mem_region(res->start, resource_size(res));
clk_disable(clk);
clk_put(clk);
return 0;
}
static struct platform_driver mxc_rnga_driver = {
.driver = {
.name = "mxc_rnga",
.owner = THIS_MODULE,
},
.remove = __exit_p(mxc_rnga_remove),
};
static int __init mod_init(void)
{
return platform_driver_probe(&mxc_rnga_driver, mxc_rnga_probe);
}
static void __exit mod_exit(void)
{
platform_driver_unregister(&mxc_rnga_driver);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("H/W RNGA driver for i.MX");
MODULE_LICENSE("GPL");
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