1 files changed, 158 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/sunxi_sid.c b/drivers/misc/eeprom/sunxi_sid.c
new file mode 100644
index 000000000000..9c34e5704304
--- /dev/null
+++ b/drivers/misc/eeprom/sunxi_sid.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
+ * http://www.linux-sunxi.org
+ *
+ * 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.
+ *
+ * This driver exposes the Allwinner security ID, efuses exported in byte-
+ * sized chunks.
+ */
+
+#include <linux/compiler.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#define DRV_NAME "sunxi-sid"
+
+struct sunxi_sid_data {
+	void __iomem *reg_base;
+	unsigned int keysize;
+};
+
+/* 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_data *sid_data,
+			      const unsigned int offset)
+{
+	u32 sid_key;
+
+	if (offset >= sid_data->keysize)
+		return 0;
+
+	sid_key = ioread32be(sid_data->reg_base + round_down(offset, 4));
+	sid_key >>= (offset % 4) * 8;
+
+	return sid_key; /* Only return the last byte */
+}
+
+static ssize_t sid_read(struct file *fd, struct kobject *kobj,
+			struct bin_attribute *attr, char *buf,
+			loff_t pos, size_t size)
+{
+	struct platform_device *pdev;
+	struct sunxi_sid_data *sid_data;
+	int i;
+
+	pdev = to_platform_device(kobj_to_dev(kobj));
+	sid_data = platform_get_drvdata(pdev);
+
+	if (pos < 0 || pos >= sid_data->keysize)
+		return 0;
+	if (size > sid_data->keysize - pos)
+		size = sid_data->keysize - pos;
+
+	for (i = 0; i < size; i++)
+		buf[i] = sunxi_sid_read_byte(sid_data, pos + i);
+
+	return i;
+}
+
+static struct bin_attribute sid_bin_attr = {
+	.attr = { .name = "eeprom", .mode = S_IRUGO, },
+	.read = sid_read,
+};
+
+static int sunxi_sid_remove(struct platform_device *pdev)
+{
+	device_remove_bin_file(&pdev->dev, &sid_bin_attr);
+	dev_dbg(&pdev->dev, "driver unloaded\n");
+
+	return 0;
+}
+
+static const struct of_device_id sunxi_sid_of_match[] = {
+	{ .compatible = "allwinner,sun4i-sid", .data = (void *)16},
+	{ .compatible = "allwinner,sun7i-a20-sid", .data = (void *)512},
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
+
+static int sunxi_sid_probe(struct platform_device *pdev)
+{
+	struct sunxi_sid_data *sid_data;
+	struct resource *res;
+	const struct of_device_id *of_dev_id;
+	u8 *entropy;
+	unsigned int i;
+
+	sid_data = devm_kzalloc(&pdev->dev, sizeof(struct sunxi_sid_data),
+				GFP_KERNEL);
+	if (!sid_data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sid_data->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(sid_data->reg_base))
+		return PTR_ERR(sid_data->reg_base);
+
+	of_dev_id = of_match_device(sunxi_sid_of_match, &pdev->dev);
+	if (!of_dev_id)
+		return -ENODEV;
+	sid_data->keysize = (int)of_dev_id->data;
+
+	platform_set_drvdata(pdev, sid_data);
+
+	sid_bin_attr.size = sid_data->keysize;
+	if (device_create_bin_file(&pdev->dev, &sid_bin_attr))
+		return -ENODEV;
+
+	entropy = kzalloc(sizeof(u8) * sid_data->keysize, GFP_KERNEL);
+	for (i = 0; i < sid_data->keysize; i++)
+		entropy[i] = sunxi_sid_read_byte(sid_data, i);
+	add_device_randomness(entropy, sid_data->keysize);
+	kfree(entropy);
+
+	dev_dbg(&pdev->dev, "loaded\n");
+
+	return 0;
+}
+
+static struct platform_driver sunxi_sid_driver = {
+	.probe = sunxi_sid_probe,
+	.remove = sunxi_sid_remove,
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.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");