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/*
* Allwinner sunXi SoCs Security ID support.
*
* Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
* Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/device.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/random.h>
static struct nvmem_config econfig = {
.name = "sunxi-sid",
.read_only = true,
.stride = 4,
.word_size = 1,
.owner = THIS_MODULE,
};
struct sunxi_sid {
void __iomem *base;
};
/* We read the entire key, due to a 32 bit read alignment requirement. Since we
* want to return the requested byte, this results in somewhat slower code and
* uses 4 times more reads as needed but keeps code simpler. Since the SID is
* only very rarely probed, this is not really an issue.
*/
static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
const unsigned int offset)
{
u32 sid_key;
sid_key = ioread32be(sid->base + round_down(offset, 4));
sid_key >>= (offset % 4) * 8;
return sid_key; /* Only return the last byte */
}
static int sunxi_sid_read(void *context, unsigned int offset,
void *val, size_t bytes)
{
struct sunxi_sid *sid = context;
u8 *buf = val;
while (bytes--)
*buf++ = sunxi_sid_read_byte(sid, offset++);
return 0;
}
static int sunxi_sid_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct resource *res;
struct nvmem_device *nvmem;
struct sunxi_sid *sid;
int ret, i, size;
char *randomness;
sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
if (!sid)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
sid->base = devm_ioremap_resource(dev, res);
if (IS_ERR(sid->base))
return PTR_ERR(sid->base);
size = resource_size(res) - 1;
econfig.size = resource_size(res);
econfig.dev = dev;
econfig.reg_read = sunxi_sid_read;
econfig.priv = sid;
nvmem = nvmem_register(&econfig);
if (IS_ERR(nvmem))
return PTR_ERR(nvmem);
randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL);
if (!randomness) {
ret = -EINVAL;
goto err_unreg_nvmem;
}
for (i = 0; i < size; i++)
randomness[i] = sunxi_sid_read_byte(sid, i);
add_device_randomness(randomness, size);
kfree(randomness);
platform_set_drvdata(pdev, nvmem);
return 0;
err_unreg_nvmem:
nvmem_unregister(nvmem);
return ret;
}
static int sunxi_sid_remove(struct platform_device *pdev)
{
struct nvmem_device *nvmem = platform_get_drvdata(pdev);
return nvmem_unregister(nvmem);
}
static const struct of_device_id sunxi_sid_of_match[] = {
{ .compatible = "allwinner,sun4i-a10-sid" },
{ .compatible = "allwinner,sun7i-a20-sid" },
{/* sentinel */},
};
MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
static struct platform_driver sunxi_sid_driver = {
.probe = sunxi_sid_probe,
.remove = sunxi_sid_remove,
.driver = {
.name = "eeprom-sunxi-sid",
.of_match_table = sunxi_sid_of_match,
},
};
module_platform_driver(sunxi_sid_driver);
MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
MODULE_DESCRIPTION("Allwinner sunxi security id driver");
MODULE_LICENSE("GPL");
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