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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2020, Matthias Brugger <mbrugger@suse.com>
*
* Driver for Raspberry Pi hardware random number generator
*/
#include <common.h>
#include <dm.h>
#include <linux/delay.h>
#include <rng.h>
#include <asm/io.h>
#define usleep_range(a, b) udelay((b))
#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_NIST_FAIL_IRQ_MASK 0x00000020
#define RNG_FIFO_DATA_OFFSET 0x20
#define RNG_FIFO_COUNT_OFFSET 0x24
#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF
struct iproc_rng200_plat {
void __iomem *base;
};
static void iproc_rng200_enable(struct iproc_rng200_plat *pdata, bool enable)
{
void __iomem *rng_base = pdata->base;
u32 val;
val = readl(rng_base + RNG_CTRL_OFFSET);
val &= ~RNG_CTRL_RNG_RBGEN_MASK;
if (enable)
val |= RNG_CTRL_RNG_RBGEN_ENABLE;
else
val &= ~RNG_CTRL_RNG_RBGEN_ENABLE;
writel(val, rng_base + RNG_CTRL_OFFSET);
}
static void iproc_rng200_restart(struct iproc_rng200_plat *pdata)
{
void __iomem *rng_base = pdata->base;
u32 val;
iproc_rng200_enable(pdata, false);
/* Clear all interrupt status */
writel(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
/* Reset RNG and RBG */
val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
val |= RBG_SOFT_RESET;
writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
val |= RNG_SOFT_RESET;
writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
val &= ~RNG_SOFT_RESET;
writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
val &= ~RBG_SOFT_RESET;
writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
iproc_rng200_enable(pdata, true);
}
static int iproc_rng200_read(struct udevice *dev, void *data, size_t len)
{
struct iproc_rng200_plat *priv = dev_get_plat(dev);
char *buf = (char *)data;
u32 num_remaining = len;
u32 status;
#define MAX_RESETS_PER_READ 1
u32 num_resets = 0;
while (num_remaining > 0) {
/* Is RNG sane? If not, reset it. */
status = readl(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 len - num_remaining;
iproc_rng200_restart(priv);
num_resets++;
}
/* Are there any random numbers available? */
if ((readl(priv->base + RNG_FIFO_COUNT_OFFSET) &
RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
if (num_remaining >= sizeof(u32)) {
/* Buffer has room to store entire word */
*(u32 *)buf = readl(priv->base +
RNG_FIFO_DATA_OFFSET);
buf += sizeof(u32);
num_remaining -= sizeof(u32);
} else {
/* Buffer can only store partial word */
u32 rnd_number = readl(priv->base +
RNG_FIFO_DATA_OFFSET);
memcpy(buf, &rnd_number, num_remaining);
buf += num_remaining;
num_remaining = 0;
}
} else {
/* Can wait, give others chance to run */
usleep_range(min(num_remaining * 10, 500U), 500);
}
}
return 0;
}
static int iproc_rng200_probe(struct udevice *dev)
{
struct iproc_rng200_plat *priv = dev_get_plat(dev);
iproc_rng200_enable(priv, true);
return 0;
}
static int iproc_rng200_remove(struct udevice *dev)
{
struct iproc_rng200_plat *priv = dev_get_plat(dev);
iproc_rng200_enable(priv, false);
return 0;
}
static int iproc_rng200_of_to_plat(struct udevice *dev)
{
struct iproc_rng200_plat *pdata = dev_get_plat(dev);
pdata->base = devfdt_map_physmem(dev, sizeof(void *));
if (!pdata->base)
return -ENODEV;
return 0;
}
static const struct dm_rng_ops iproc_rng200_ops = {
.read = iproc_rng200_read,
};
static const struct udevice_id iproc_rng200_rng_match[] = {
{ .compatible = "brcm,bcm2711-rng200", },
{ .compatible = "brcm,iproc-rng200", },
{},
};
U_BOOT_DRIVER(iproc_rng200_rng) = {
.name = "iproc_rng200-rng",
.id = UCLASS_RNG,
.of_match = iproc_rng200_rng_match,
.ops = &iproc_rng200_ops,
.probe = iproc_rng200_probe,
.remove = iproc_rng200_remove,
.priv_auto = sizeof(struct iproc_rng200_plat),
.of_to_plat = iproc_rng200_of_to_plat,
};
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