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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2020, Heinrich Schuchardt <xypron.glpk@gmx.de>
*
* Driver for Amlogic hardware random number generator
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <rng.h>
#include <asm/io.h>
#include <linux/iopoll.h>
#define RNG_DATA 0x00
#define RNG_S4_DATA 0x08
#define RNG_S4_CFG 0x00
#define RUN_BIT BIT(0)
#define SEED_READY_STS_BIT BIT(31)
struct meson_rng_priv {
u32 (*read)(fdt_addr_t base);
};
struct meson_rng_plat {
fdt_addr_t base;
struct clk clk;
struct meson_rng_priv *priv;
};
/**
* meson_rng_read() - fill buffer with random bytes
*
* @buffer: buffer to receive data
* @size: size of buffer
*
* Return: 0
*/
static int meson_rng_read(struct udevice *dev, void *data, size_t len)
{
struct meson_rng_plat *pdata = dev_get_plat(dev);
struct meson_rng_priv *priv = pdata->priv;
char *buffer = (char *)data;
while (len) {
u32 rand = priv->read(pdata->base);
size_t step;
if (len >= 4)
step = 4;
else
step = len;
memcpy(buffer, &rand, step);
buffer += step;
len -= step;
}
return 0;
}
static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
{
u32 status = 0;
int ret;
ret = readl_relaxed_poll_timeout(cfg_addr,
status, !(status & bit),
10000);
if (ret)
return -EBUSY;
return 0;
}
static u32 meson_common_rng_read(fdt_addr_t base)
{
return readl(base);
}
static u32 meson_s4_rng_read(fdt_addr_t base)
{
void __iomem *cfg_addr = (void *)base + RNG_S4_CFG;
int err;
writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);
err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
if (err) {
pr_err("Seed isn't ready, try again\n");
return err;
}
err = meson_rng_wait_status(cfg_addr, RUN_BIT);
if (err) {
pr_err("Can't get random number, try again\n");
return err;
}
return readl_relaxed(base + RNG_S4_DATA);
}
/**
* meson_rng_probe() - probe rng device
*
* @dev: device
* Return: 0 if ok
*/
static int meson_rng_probe(struct udevice *dev)
{
struct meson_rng_plat *pdata = dev_get_plat(dev);
int err;
err = clk_enable(&pdata->clk);
if (err)
return err;
pdata->priv = (struct meson_rng_priv *)dev_get_driver_data(dev);
return 0;
}
/**
* meson_rng_remove() - deinitialize rng device
*
* @dev: device
* Return: 0 if ok
*/
static int meson_rng_remove(struct udevice *dev)
{
struct meson_rng_plat *pdata = dev_get_plat(dev);
return clk_disable(&pdata->clk);
}
/**
* meson_rng_of_to_plat() - transfer device tree data to plaform data
*
* @dev: device
* Return: 0 if ok
*/
static int meson_rng_of_to_plat(struct udevice *dev)
{
struct meson_rng_plat *pdata = dev_get_plat(dev);
int err;
pdata->base = dev_read_addr(dev);
if (!pdata->base)
return -ENODEV;
/* Get optional "core" clock */
err = clk_get_by_name_optional(dev, "core", &pdata->clk);
if (err)
return err;
return 0;
}
static const struct dm_rng_ops meson_rng_ops = {
.read = meson_rng_read,
};
static const struct meson_rng_priv meson_rng_priv = {
.read = meson_common_rng_read,
};
static const struct meson_rng_priv meson_rng_priv_s4 = {
.read = meson_s4_rng_read,
};
static const struct udevice_id meson_rng_match[] = {
{
.compatible = "amlogic,meson-rng",
.data = (ulong)&meson_rng_priv,
},
{
.compatible = "amlogic,meson-s4-rng",
.data = (ulong)&meson_rng_priv_s4,
},
{},
};
U_BOOT_DRIVER(meson_rng) = {
.name = "meson-rng",
.id = UCLASS_RNG,
.of_match = meson_rng_match,
.ops = &meson_rng_ops,
.probe = meson_rng_probe,
.remove = meson_rng_remove,
.plat_auto = sizeof(struct meson_rng_plat),
.of_to_plat = meson_rng_of_to_plat,
};
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