158 lines
4.2 KiB
C
158 lines
4.2 KiB
C
/*
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* Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
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* http://www.linux-sunxi.org
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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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* This driver exposes the Allwinner security ID, efuses exported in byte-
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* sized chunks.
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*/
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#include <linux/compiler.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/sysfs.h>
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#include <linux/types.h>
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#define DRV_NAME "sunxi-sid"
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struct sunxi_sid_data {
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void __iomem *reg_base;
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unsigned int keysize;
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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_data *sid_data,
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const unsigned int offset)
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{
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u32 sid_key;
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if (offset >= sid_data->keysize)
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return 0;
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sid_key = ioread32be(sid_data->reg_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 ssize_t sid_read(struct file *fd, struct kobject *kobj,
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struct bin_attribute *attr, char *buf,
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loff_t pos, size_t size)
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{
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struct platform_device *pdev;
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struct sunxi_sid_data *sid_data;
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int i;
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pdev = to_platform_device(kobj_to_dev(kobj));
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sid_data = platform_get_drvdata(pdev);
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if (pos < 0 || pos >= sid_data->keysize)
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return 0;
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if (size > sid_data->keysize - pos)
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size = sid_data->keysize - pos;
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for (i = 0; i < size; i++)
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buf[i] = sunxi_sid_read_byte(sid_data, pos + i);
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return i;
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}
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static struct bin_attribute sid_bin_attr = {
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.attr = { .name = "eeprom", .mode = S_IRUGO, },
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.read = sid_read,
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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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device_remove_bin_file(&pdev->dev, &sid_bin_attr);
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dev_dbg(&pdev->dev, "driver unloaded\n");
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return 0;
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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", .data = (void *)16},
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{ .compatible = "allwinner,sun7i-a20-sid", .data = (void *)512},
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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 int sunxi_sid_probe(struct platform_device *pdev)
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{
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struct sunxi_sid_data *sid_data;
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struct resource *res;
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const struct of_device_id *of_dev_id;
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u8 *entropy;
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unsigned int i;
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sid_data = devm_kzalloc(&pdev->dev, sizeof(struct sunxi_sid_data),
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GFP_KERNEL);
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if (!sid_data)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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sid_data->reg_base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(sid_data->reg_base))
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return PTR_ERR(sid_data->reg_base);
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of_dev_id = of_match_device(sunxi_sid_of_match, &pdev->dev);
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if (!of_dev_id)
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return -ENODEV;
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sid_data->keysize = (int)of_dev_id->data;
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platform_set_drvdata(pdev, sid_data);
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sid_bin_attr.size = sid_data->keysize;
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if (device_create_bin_file(&pdev->dev, &sid_bin_attr))
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return -ENODEV;
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entropy = kzalloc(sizeof(u8) * sid_data->keysize, GFP_KERNEL);
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for (i = 0; i < sid_data->keysize; i++)
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entropy[i] = sunxi_sid_read_byte(sid_data, i);
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add_device_randomness(entropy, sid_data->keysize);
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kfree(entropy);
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dev_dbg(&pdev->dev, "loaded\n");
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return 0;
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}
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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 = DRV_NAME,
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.owner = THIS_MODULE,
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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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