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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/delay.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
struct mxc_rng {
struct device *dev;
struct hwrng rng;
void __iomem *mem;
struct clk *clk;
};
static int mxc_rnga_data_present(struct hwrng *rng, int wait)
{
int i;
struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
for (i = 0; i < 20; i++) {
/* how many random numbers are in FIFO? [0-16] */
int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) &
RNGA_STATUS_LEVEL_MASK) >> 8;
if (level || !wait)
return !!level;
udelay(10);
}
return 0;
}
static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
{
int err;
u32 ctrl;
struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
/* retrieve a random number from FIFO */
*data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO);
/* some error while reading this random number? */
err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
/* if error: clear error interrupt, but doesn't return random number */
if (err) {
dev_dbg(mxc_rng->dev, "Error while reading random number!\n");
ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
__raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
mxc_rng->mem + RNGA_CONTROL);
return 0;
} else
return 4;
}
static int mxc_rnga_init(struct hwrng *rng)
{
u32 ctrl, osc;
struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
/* wake up */
ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
__raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL);
/* verify if oscillator is working */
osc = __raw_readl(mxc_rng->mem + RNGA_STATUS);
if (osc & RNGA_STATUS_OSC_DEAD) {
dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n");
return -ENODEV;
}
/* go running */
ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
__raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
return 0;
}
static void mxc_rnga_cleanup(struct hwrng *rng)
{
u32 ctrl;
struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
/* stop rnga */
__raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
}
static int __init mxc_rnga_probe(struct platform_device *pdev)
{
int err = -ENODEV;
struct resource *res;
struct mxc_rng *mxc_rng;
mxc_rng = devm_kzalloc(&pdev->dev, sizeof(struct mxc_rng),
GFP_KERNEL);
if (!mxc_rng)
return -ENOMEM;
mxc_rng->dev = &pdev->dev;
mxc_rng->rng.name = "mxc-rnga";
mxc_rng->rng.init = mxc_rnga_init;
mxc_rng->rng.cleanup = mxc_rnga_cleanup,
mxc_rng->rng.data_present = mxc_rnga_data_present,
mxc_rng->rng.data_read = mxc_rnga_data_read,
mxc_rng->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(mxc_rng->clk)) {
dev_err(&pdev->dev, "Could not get rng_clk!\n");
err = PTR_ERR(mxc_rng->clk);
goto out;
}
clk_prepare_enable(mxc_rng->clk);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mxc_rng->mem = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(mxc_rng->mem)) {
err = PTR_ERR(mxc_rng->mem);
goto err_ioremap;
}
err = hwrng_register(&mxc_rng->rng);
if (err) {
dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
goto err_ioremap;
}
dev_info(&pdev->dev, "MXC RNGA Registered.\n");
return 0;
err_ioremap:
clk_disable_unprepare(mxc_rng->clk);
out:
return err;
}
static int __exit mxc_rnga_remove(struct platform_device *pdev)
{
struct mxc_rng *mxc_rng = platform_get_drvdata(pdev);
hwrng_unregister(&mxc_rng->rng);
clk_disable_unprepare(mxc_rng->clk);
return 0;
}
static struct platform_driver mxc_rnga_driver = {
.driver = {
.name = "mxc_rnga",
.owner = THIS_MODULE,
},
.remove = __exit_p(mxc_rnga_remove),
};
module_platform_driver_probe(mxc_rnga_driver, mxc_rnga_probe);
MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("H/W RNGA driver for i.MX");
MODULE_LICENSE("GPL");
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