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