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/*
* Copyright (C) 2015 Broadcom Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation version 2.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
/*
* DESCRIPTION: The Broadcom iProc RNG200 Driver
*/
#include <linux/hw_random.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
/* Registers */
#define RNG_CTRL_OFFSET 0x00
#define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF
#define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001
#define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000
#define RNG_SOFT_RESET_OFFSET 0x04
#define RNG_SOFT_RESET 0x00000001
#define RBG_SOFT_RESET_OFFSET 0x08
#define RBG_SOFT_RESET 0x00000001
#define RNG_INT_STATUS_OFFSET 0x18
#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x80000000
#define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x00020000
#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x00000020
#define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x00000001
#define RNG_FIFO_DATA_OFFSET 0x20
#define RNG_FIFO_COUNT_OFFSET 0x24
#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF
struct iproc_rng200_dev {
void __iomem *base;
};
static void iproc_rng200_restart(void __iomem *rng_base)
{
uint32_t val;
/* Disable RBG */
val = ioread32(rng_base + RNG_CTRL_OFFSET);
val &= ~RNG_CTRL_RNG_RBGEN_MASK;
val |= RNG_CTRL_RNG_RBGEN_DISABLE;
iowrite32(val, rng_base + RNG_CTRL_OFFSET);
/* Clear all interrupt status */
iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
/* Reset RNG and RBG */
val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
val |= RBG_SOFT_RESET;
iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
val |= RNG_SOFT_RESET;
iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
val &= ~RNG_SOFT_RESET;
iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
val &= ~RBG_SOFT_RESET;
iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
/* Enable RBG */
val = ioread32(rng_base + RNG_CTRL_OFFSET);
val &= ~RNG_CTRL_RNG_RBGEN_MASK;
val |= RNG_CTRL_RNG_RBGEN_ENABLE;
iowrite32(val, rng_base + RNG_CTRL_OFFSET);
}
static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
uint32_t status;
uint32_t num_remaining = max;
struct iproc_rng200_dev *priv = (struct iproc_rng200_dev *)rng->priv;
#define MAX_RESETS_PER_READ 1
uint32_t num_resets = 0;
#define MAX_IDLE_TIME (1 * HZ)
unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;
while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {
/* Is RNG sane? If not, reset it. */
status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);
if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |
RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {
if (num_resets >= MAX_RESETS_PER_READ)
return max - num_remaining;
iproc_rng200_restart(priv->base);
num_resets++;
}
/* Are there any random numbers available? */
if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &
RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
if (num_remaining >= sizeof(uint32_t)) {
/* Buffer has room to store entire word */
*(uint32_t *)buf = ioread32(priv->base +
RNG_FIFO_DATA_OFFSET);
buf += sizeof(uint32_t);
num_remaining -= sizeof(uint32_t);
} else {
/* Buffer can only store partial word */
uint32_t rnd_number = ioread32(priv->base +
RNG_FIFO_DATA_OFFSET);
memcpy(buf, &rnd_number, num_remaining);
buf += num_remaining;
num_remaining = 0;
}
/* Reset the IDLE timeout */
idle_endtime = jiffies + MAX_IDLE_TIME;
} else {
if (!wait)
/* Cannot wait, return immediately */
return max - num_remaining;
/* Can wait, give others chance to run */
usleep_range(min(num_remaining * 10, 500U), 500);
}
}
return max - num_remaining;
}
static int iproc_rng200_init(struct hwrng *rng)
{
uint32_t val;
struct iproc_rng200_dev *priv;
priv = (struct iproc_rng200_dev *)rng->priv;
/* Setup RNG. */
val = ioread32(priv->base + RNG_CTRL_OFFSET);
val &= ~RNG_CTRL_RNG_RBGEN_MASK;
val |= RNG_CTRL_RNG_RBGEN_ENABLE;
iowrite32(val, priv->base + RNG_CTRL_OFFSET);
return 0;
}
static void iproc_rng200_cleanup(struct hwrng *rng)
{
uint32_t val;
struct iproc_rng200_dev *priv;
priv = (struct iproc_rng200_dev *)rng->priv;
/* Disable RNG hardware */
val = ioread32(priv->base + RNG_CTRL_OFFSET);
val &= ~RNG_CTRL_RNG_RBGEN_MASK;
val |= RNG_CTRL_RNG_RBGEN_DISABLE;
iowrite32(val, priv->base + RNG_CTRL_OFFSET);
}
static struct hwrng iproc_rng200_ops = {
.name = "iproc-rng200",
.read = iproc_rng200_read,
.init = iproc_rng200_init,
.cleanup = iproc_rng200_cleanup,
};
static int iproc_rng200_probe(struct platform_device *pdev)
{
struct iproc_rng200_dev *priv;
struct resource *res;
struct device *dev = &pdev->dev;
int ret;
priv = devm_kzalloc(dev, sizeof(struct iproc_rng200_dev), GFP_KERNEL);
if (!priv)
return -ENOMEM;
iproc_rng200_ops.priv = (unsigned long)priv;
platform_set_drvdata(pdev, priv);
/* Map peripheral */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(dev, "failed to get rng resources\n");
return -EINVAL;
}
priv->base = devm_ioremap_resource(dev, res);
if (IS_ERR(priv->base)) {
dev_err(dev, "failed to remap rng regs\n");
return PTR_ERR(priv->base);
}
/* Register driver */
ret = hwrng_register(&iproc_rng200_ops);
if (ret) {
dev_err(dev, "hwrng registration failed\n");
return ret;
}
dev_info(dev, "hwrng registered\n");
return 0;
}
static int iproc_rng200_remove(struct platform_device *pdev)
{
/* Unregister driver */
hwrng_unregister(&iproc_rng200_ops);
return 0;
}
static const struct of_device_id iproc_rng200_of_match[] = {
{ .compatible = "brcm,iproc-rng200", },
{},
};
MODULE_DEVICE_TABLE(of, iproc_rng200_of_match);
static struct platform_driver iproc_rng200_driver = {
.driver = {
.name = "iproc-rng200",
.of_match_table = iproc_rng200_of_match,
},
.probe = iproc_rng200_probe,
.remove = iproc_rng200_remove,
};
module_platform_driver(iproc_rng200_driver);
MODULE_AUTHOR("Broadcom");
MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver");
MODULE_LICENSE("GPL v2");
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