stm32mp1_rng.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2019, Linaro Limited
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <reset.h>
#include <rng.h>
#include <asm/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#define RNG_CR 0x00
#define RNG_CR_RNGEN BIT(2)
#define RNG_CR_CED BIT(5)
#define RNG_SR 0x04
#define RNG_SR_SEIS BIT(6)
#define RNG_SR_CEIS BIT(5)
#define RNG_SR_SECS BIT(2)
#define RNG_SR_DRDY BIT(0)
#define RNG_DR 0x08
struct stm32_rng_platdata {
fdt_addr_t base;
struct clk clk;
struct reset_ctl rst;
};
static int stm32_rng_read(struct udevice *dev, void *data, size_t len)
{
int retval, i;
u32 sr, count, reg;
size_t increment;
struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
while (len > 0) {
retval = readl_poll_timeout(pdata->base + RNG_SR, sr,
sr & RNG_SR_DRDY, 10000);
if (retval)
return retval;
if (sr & (RNG_SR_SEIS | RNG_SR_SECS)) {
/* As per SoC TRM */
clrbits_le32(pdata->base + RNG_SR, RNG_SR_SEIS);
for (i = 0; i < 12; i++)
readl(pdata->base + RNG_DR);
if (readl(pdata->base + RNG_SR) & RNG_SR_SEIS) {
printf("RNG Noise");
return -EIO;
}
/* start again */
continue;
}
/*
* Once the DRDY bit is set, the RNG_DR register can
* be read four consecutive times.
*/
count = 4;
while (len && count) {
reg = readl(pdata->base + RNG_DR);
memcpy(data, ®, min(len, sizeof(u32)));
increment = min(len, sizeof(u32));
data += increment;
len -= increment;
count--;
}
}
return 0;
}
static int stm32_rng_init(struct stm32_rng_platdata *pdata)
{
int err;
err = clk_enable(&pdata->clk);
if (err)
return err;
/* Disable CED */
writel(RNG_CR_RNGEN | RNG_CR_CED, pdata->base + RNG_CR);
/* clear error indicators */
writel(0, pdata->base + RNG_SR);
return 0;
}
static int stm32_rng_cleanup(struct stm32_rng_platdata *pdata)
{
writel(0, pdata->base + RNG_CR);
return clk_disable(&pdata->clk);
}
static int stm32_rng_probe(struct udevice *dev)
{
struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
reset_assert(&pdata->rst);
udelay(20);
reset_deassert(&pdata->rst);
return stm32_rng_init(pdata);
}
static int stm32_rng_remove(struct udevice *dev)
{
struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
return stm32_rng_cleanup(pdata);
}
static int stm32_rng_ofdata_to_platdata(struct udevice *dev)
{
struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
int err;
pdata->base = dev_read_addr(dev);
if (!pdata->base)
return -ENOMEM;
err = clk_get_by_index(dev, 0, &pdata->clk);
if (err)
return err;
err = reset_get_by_index(dev, 0, &pdata->rst);
if (err)
return err;
return 0;
}
static const struct dm_rng_ops stm32_rng_ops = {
.read = stm32_rng_read,
};
static const struct udevice_id stm32_rng_match[] = {
{
.compatible = "st,stm32-rng",
},
{},
};
U_BOOT_DRIVER(stm32_rng) = {
.name = "stm32-rng",
.id = UCLASS_RNG,
.of_match = stm32_rng_match,
.ops = &stm32_rng_ops,
.probe = stm32_rng_probe,
.remove = stm32_rng_remove,
.platdata_auto_alloc_size = sizeof(struct stm32_rng_platdata),
.ofdata_to_platdata = stm32_rng_ofdata_to_platdata,
};