160 lines
4.1 KiB
C
160 lines
4.1 KiB
C
/*
|
|
* RNG driver for TX4939 Random Number Generators (RNG)
|
|
*
|
|
* Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file "COPYING" in the main directory of this archive
|
|
* for more details.
|
|
*/
|
|
#include <linux/err.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/io.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/hw_random.h>
|
|
#include <linux/gfp.h>
|
|
|
|
#define TX4939_RNG_RCSR 0x00000000
|
|
#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8)
|
|
|
|
#define TX4939_RNG_RCSR_INTE 0x00000008
|
|
#define TX4939_RNG_RCSR_RST 0x00000004
|
|
#define TX4939_RNG_RCSR_FIN 0x00000002
|
|
#define TX4939_RNG_RCSR_ST 0x00000001
|
|
|
|
struct tx4939_rng {
|
|
struct hwrng rng;
|
|
void __iomem *base;
|
|
u64 databuf[3];
|
|
unsigned int data_avail;
|
|
};
|
|
|
|
static void rng_io_start(void)
|
|
{
|
|
#ifndef CONFIG_64BIT
|
|
/*
|
|
* readq is reading a 64-bit register using a 64-bit load. On
|
|
* a 32-bit kernel however interrupts or any other processor
|
|
* exception would clobber the upper 32-bit of the processor
|
|
* register so interrupts need to be disabled.
|
|
*/
|
|
local_irq_disable();
|
|
#endif
|
|
}
|
|
|
|
static void rng_io_end(void)
|
|
{
|
|
#ifndef CONFIG_64BIT
|
|
local_irq_enable();
|
|
#endif
|
|
}
|
|
|
|
static u64 read_rng(void __iomem *base, unsigned int offset)
|
|
{
|
|
return ____raw_readq(base + offset);
|
|
}
|
|
|
|
static void write_rng(u64 val, void __iomem *base, unsigned int offset)
|
|
{
|
|
return ____raw_writeq(val, base + offset);
|
|
}
|
|
|
|
static int tx4939_rng_data_present(struct hwrng *rng, int wait)
|
|
{
|
|
struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
|
|
int i;
|
|
|
|
if (rngdev->data_avail)
|
|
return rngdev->data_avail;
|
|
for (i = 0; i < 20; i++) {
|
|
rng_io_start();
|
|
if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
|
|
& TX4939_RNG_RCSR_ST)) {
|
|
rngdev->databuf[0] =
|
|
read_rng(rngdev->base, TX4939_RNG_ROR(0));
|
|
rngdev->databuf[1] =
|
|
read_rng(rngdev->base, TX4939_RNG_ROR(1));
|
|
rngdev->databuf[2] =
|
|
read_rng(rngdev->base, TX4939_RNG_ROR(2));
|
|
rngdev->data_avail =
|
|
sizeof(rngdev->databuf) / sizeof(u32);
|
|
/* Start RNG */
|
|
write_rng(TX4939_RNG_RCSR_ST,
|
|
rngdev->base, TX4939_RNG_RCSR);
|
|
wait = 0;
|
|
}
|
|
rng_io_end();
|
|
if (!wait)
|
|
break;
|
|
/* 90 bus clock cycles by default for generation */
|
|
ndelay(90 * 5);
|
|
}
|
|
return rngdev->data_avail;
|
|
}
|
|
|
|
static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer)
|
|
{
|
|
struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
|
|
|
|
rngdev->data_avail--;
|
|
*buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail);
|
|
return sizeof(u32);
|
|
}
|
|
|
|
static int __init tx4939_rng_probe(struct platform_device *dev)
|
|
{
|
|
struct tx4939_rng *rngdev;
|
|
struct resource *r;
|
|
int i;
|
|
|
|
rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
|
|
if (!rngdev)
|
|
return -ENOMEM;
|
|
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
|
|
rngdev->base = devm_ioremap_resource(&dev->dev, r);
|
|
if (IS_ERR(rngdev->base))
|
|
return PTR_ERR(rngdev->base);
|
|
|
|
rngdev->rng.name = dev_name(&dev->dev);
|
|
rngdev->rng.data_present = tx4939_rng_data_present;
|
|
rngdev->rng.data_read = tx4939_rng_data_read;
|
|
|
|
rng_io_start();
|
|
/* Reset RNG */
|
|
write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
|
|
write_rng(0, rngdev->base, TX4939_RNG_RCSR);
|
|
/* Start RNG */
|
|
write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
|
|
rng_io_end();
|
|
/*
|
|
* Drop first two results. From the datasheet:
|
|
* The quality of the random numbers generated immediately
|
|
* after reset can be insufficient. Therefore, do not use
|
|
* random numbers obtained from the first and second
|
|
* generations; use the ones from the third or subsequent
|
|
* generation.
|
|
*/
|
|
for (i = 0; i < 2; i++) {
|
|
rngdev->data_avail = 0;
|
|
if (!tx4939_rng_data_present(&rngdev->rng, 1))
|
|
return -EIO;
|
|
}
|
|
|
|
platform_set_drvdata(dev, rngdev);
|
|
return devm_hwrng_register(&dev->dev, &rngdev->rng);
|
|
}
|
|
|
|
static struct platform_driver tx4939_rng_driver = {
|
|
.driver = {
|
|
.name = "tx4939-rng",
|
|
},
|
|
};
|
|
|
|
module_platform_driver_probe(tx4939_rng_driver, tx4939_rng_probe);
|
|
|
|
MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
|
|
MODULE_LICENSE("GPL");
|