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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/regmap.h>
#include <linux/slab.h>
#include <linux/random.h>
static struct nvmem_config econfig = {
.name = "sunxi-sid",
.read_only = true,
.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,
const void *reg, size_t reg_size,
void *val, size_t val_size)
{
struct sunxi_sid *sid = context;
unsigned int offset = *(u32 *)reg;
u8 *buf = val;
while (val_size) {
*buf++ = sunxi_sid_read_byte(sid, offset);
val_size--;
offset++;
}
return 0;
}
static int sunxi_sid_write(void *context, const void *data, size_t count)
{
/* Unimplemented, dummy to keep regmap core happy */
return 0;
}
static struct regmap_bus sunxi_sid_bus = {
.read = sunxi_sid_read,
.write = sunxi_sid_write,
.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
};
static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg)
{
return false;
}
static struct regmap_config sunxi_sid_regmap_config = {
.reg_bits = 32,
.val_bits = 8,
.reg_stride = 1,
.writeable_reg = sunxi_sid_writeable_reg,
};
static int sunxi_sid_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct resource *res;
struct nvmem_device *nvmem;
struct regmap *regmap;
struct sunxi_sid *sid;
int 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;
sunxi_sid_regmap_config.max_register = size;
regmap = devm_regmap_init(dev, &sunxi_sid_bus, sid,
&sunxi_sid_regmap_config);
if (IS_ERR(regmap)) {
dev_err(dev, "regmap init failed\n");
return PTR_ERR(regmap);
}
econfig.dev = dev;
nvmem = nvmem_register(&econfig);
if (IS_ERR(nvmem))
return PTR_ERR(nvmem);
randomness = kzalloc(sizeof(u8) * size, GFP_KERNEL);
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;
}
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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