Commit 049a947c authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
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MIPS: hwrng: Add TX4939 RNG driver

This patch adds support for the integrated RNG of the TX4939 SoC.
Signed-off-by: default avatarAtsushi Nemoto <>
Acked-by: default avatarMatt Mackall <>
Signed-off-by: default avatarRalf Baechle <>
parent c3b28ae2
......@@ -149,6 +149,19 @@ config HW_RANDOM_VIRTIO
To compile this driver as a module, choose M here: the
module will be called virtio-rng. If unsure, say N.
config HW_RANDOM_TX4939
tristate "TX4939 Random Number Generator support"
depends on HW_RANDOM && SOC_TX4939
default HW_RANDOM
This driver provides kernel-side support for the Random Number
Generator hardware found on TX4939 SoC.
To compile this driver as a module, choose M here: the
module will be called tx4939-rng.
If unsure, say Y.
tristate "Freescale i.MX RNGA Random Number Generator"
......@@ -15,4 +15,5 @@ obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o
obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o
obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
* RNG driver for TX4939 Random Number Generators (RNG)
* Copyright (C) 2009 Atsushi Nemoto <>
* 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/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>
#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.
static void rng_io_end(void)
#ifndef CONFIG_64BIT
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++) {
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 */
rngdev->base, TX4939_RNG_RCSR);
wait = 0;
if (!wait)
/* 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);
*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;
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!r)
return -EBUSY;
rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
if (!rngdev)
return -ENOMEM;
if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
return -EBUSY;
rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r));
if (!rngdev->base)
return -EBUSY;
rngdev-> = dev_name(&dev->dev);
rngdev->rng.data_present = tx4939_rng_data_present;
rngdev->rng.data_read = tx4939_rng_data_read;
/* 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);
* 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 hwrng_register(&rngdev->rng);
static int __exit tx4939_rng_remove(struct platform_device *dev)
struct tx4939_rng *rngdev = platform_get_drvdata(dev);
platform_set_drvdata(dev, NULL);
return 0;
static struct platform_driver tx4939_rng_driver = {
.driver = {
.name = "tx4939-rng",
.owner = THIS_MODULE,
.remove = tx4939_rng_remove,
static int __init tx4939rng_init(void)
return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
static void __exit tx4939rng_exit(void)
MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
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