meson-rng.c
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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>
struct meson_rng_platdata {
fdt_addr_t base;
struct clk clk;
};
/**
* 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_platdata *pdata = dev_get_platdata(dev);
char *buffer = (char *)data;
while (len) {
u32 rand = readl(pdata->base);
size_t step;
if (len >= 4)
step = 4;
else
step = len;
memcpy(buffer, &rand, step);
buffer += step;
len -= step;
}
return 0;
}
/**
* meson_rng_probe() - probe rng device
*
* @dev: device
* Return: 0 if ok
*/
static int meson_rng_probe(struct udevice *dev)
{
struct meson_rng_platdata *pdata = dev_get_platdata(dev);
int err;
err = clk_enable(&pdata->clk);
if (err)
return err;
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_platdata *pdata = dev_get_platdata(dev);
return clk_disable(&pdata->clk);
}
/**
* meson_rng_ofdata_to_platdata() - transfer device tree data to plaform data
*
* @dev: device
* Return: 0 if ok
*/
static int meson_rng_ofdata_to_platdata(struct udevice *dev)
{
struct meson_rng_platdata *pdata = dev_get_platdata(dev);
int err;
pdata->base = dev_read_addr(dev);
if (!pdata->base)
return -ENODEV;
err = clk_get_by_name(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 udevice_id meson_rng_match[] = {
{
.compatible = "amlogic,meson-rng",
},
{},
};
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,
.platdata_auto_alloc_size = sizeof(struct meson_rng_platdata),
.ofdata_to_platdata = meson_rng_ofdata_to_platdata,
};