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290 lines
9.4 KiB
290 lines
9.4 KiB
From 1d4b3ab562fa87e2c7f05cf92af1ff4b6cd42581 Mon Sep 17 00:00:00 2001
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From: Oliver Schinagl <oliver@schinagl.nl>
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Date: Tue, 3 Sep 2013 12:33:27 +0200
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Subject: [PATCH] ARM: sunxi: Initial support for Allwinner's Security ID fuses
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Allwinner has electric fuses (efuse) on their line of chips. This driver
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reads those fuses, seeds the kernel entropy and exports them as a sysfs
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node.
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These fuses are most likely to be programmed at the factory, encoding
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things like Chip ID, some sort of serial number, etc. and appear to be
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reasonably unique.
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While in theory, these should be writeable by the user, it will probably
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be inconvenient to do so. Allwinner recommends that a certain input pin,
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labeled 'efuse_vddq', be connected to GND. To write these fuses however,
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a 2.5 V programming voltage needs to be applied to this pin.
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Even so, they can still be used to generate a board-unique mac from,
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board unique RSA key and seed the kernel RNG.
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On sun7i additional storage is available, this is initially used for an
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UEFI BOOT key, Secure JTAG key, HDMI-HDCP key and vendor specific keys.
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Currently supported are the following known chips:
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Allwinner sun4i (A10)
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Allwinner sun5i (A10s, A13)
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Allwinner sun7i (A20)
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Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
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---
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Documentation/ABI/testing/sysfs-driver-sunxi-sid | 22 +++
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.../bindings/misc/allwinner,sunxi-sid.txt | 17 +++
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drivers/misc/eeprom/Kconfig | 13 ++
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drivers/misc/eeprom/Makefile | 1 +
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drivers/misc/eeprom/sunxi_sid.c | 158 +++++++++++++++++++++
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5 files changed, 211 insertions(+)
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create mode 100644 Documentation/ABI/testing/sysfs-driver-sunxi-sid
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create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-sid.txt
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create mode 100644 drivers/misc/eeprom/sunxi_sid.c
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diff --git a/Documentation/ABI/testing/sysfs-driver-sunxi-sid b/Documentation/ABI/testing/sysfs-driver-sunxi-sid
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new file mode 100644
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index 0000000..ffb9536
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--- /dev/null
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+++ b/Documentation/ABI/testing/sysfs-driver-sunxi-sid
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@@ -0,0 +1,22 @@
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+What: /sys/devices/*/<our-device>/eeprom
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+Date: August 2013
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+Contact: Oliver Schinagl <oliver@schinagl.nl>
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+Description: read-only access to the SID (Security-ID) on current
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+ A-series SoC's from Allwinner. Currently supports A10, A10s, A13
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+ and A20 CPU's. The earlier A1x series of SoCs exports 16 bytes,
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+ whereas the newer A20 SoC exposes 512 bytes split into sections.
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+ Besides the 16 bytes of SID, there's also an SJTAG area,
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+ HDMI-HDCP key and some custom keys. Below a quick overview, for
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+ details see the user manual:
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+ 0x000 128 bit root-key (sun[457]i)
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+ 0x010 128 bit boot-key (sun7i)
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+ 0x020 64 bit security-jtag-key (sun7i)
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+ 0x028 16 bit key configuration (sun7i)
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+ 0x02b 16 bit custom-vendor-key (sun7i)
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+ 0x02c 320 bit low general key (sun7i)
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+ 0x040 32 bit read-control access (sun7i)
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+ 0x064 224 bit low general key (sun7i)
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+ 0x080 2304 bit HDCP-key (sun7i)
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+ 0x1a0 768 bit high general key (sun7i)
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+Users: any user space application which wants to read the SID on
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+ Allwinner's A-series of CPU's.
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diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-sid.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-sid.txt
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new file mode 100644
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index 0000000..68ba372
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--- /dev/null
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+++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-sid.txt
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@@ -0,0 +1,17 @@
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+Allwinner sunxi-sid
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+
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+Required properties:
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+- compatible: "allwinner,sun4i-sid" or "allwinner,sun7i-a20-sid".
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+- reg: Should contain registers location and length
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+
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+Example for sun4i:
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+ sid@01c23800 {
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+ compatible = "allwinner,sun4i-sid";
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+ reg = <0x01c23800 0x10>
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+ };
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+
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+Example for sun7i:
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+ sid@01c23800 {
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+ compatible = "allwinner,sun7i-a20-sid";
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+ reg = <0x01c23800 0x200>
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+ };
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diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
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index 04f2e1f..9536852f 100644
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--- a/drivers/misc/eeprom/Kconfig
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+++ b/drivers/misc/eeprom/Kconfig
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@@ -96,4 +96,17 @@ config EEPROM_DIGSY_MTC_CFG
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If unsure, say N.
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+config EEPROM_SUNXI_SID
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+ tristate "Allwinner sunxi security ID support"
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+ depends on ARCH_SUNXI && SYSFS
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+ help
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+ This is a driver for the 'security ID' available on various Allwinner
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+ devices.
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+
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+ Due to the potential risks involved with changing e-fuses,
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+ this driver is read-only.
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+
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+ This driver can also be built as a module. If so, the module
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+ will be called sunxi_sid.
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+
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endmenu
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diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
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index fc1e81d..9507aec 100644
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--- a/drivers/misc/eeprom/Makefile
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+++ b/drivers/misc/eeprom/Makefile
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@@ -4,4 +4,5 @@ obj-$(CONFIG_EEPROM_LEGACY) += eeprom.o
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obj-$(CONFIG_EEPROM_MAX6875) += max6875.o
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obj-$(CONFIG_EEPROM_93CX6) += eeprom_93cx6.o
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obj-$(CONFIG_EEPROM_93XX46) += eeprom_93xx46.o
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+obj-$(CONFIG_EEPROM_SUNXI_SID) += sunxi_sid.o
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obj-$(CONFIG_EEPROM_DIGSY_MTC_CFG) += digsy_mtc_eeprom.o
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diff --git a/drivers/misc/eeprom/sunxi_sid.c b/drivers/misc/eeprom/sunxi_sid.c
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new file mode 100644
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index 0000000..9c34e57
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--- /dev/null
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+++ b/drivers/misc/eeprom/sunxi_sid.c
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@@ -0,0 +1,158 @@
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+/*
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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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+
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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/init.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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+
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+#define DRV_NAME "sunxi-sid"
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+
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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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+
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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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+
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+ if (offset >= sid_data->keysize)
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+ return 0;
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+
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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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+
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+ return sid_key; /* Only return the last byte */
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+}
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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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+
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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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+
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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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+
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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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+
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+ return i;
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+}
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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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+
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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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+
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+ return 0;
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+}
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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-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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+
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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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+
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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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+
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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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+
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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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+
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+ platform_set_drvdata(pdev, sid_data);
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+
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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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+
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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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+
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+ dev_dbg(&pdev->dev, "loaded\n");
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+
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+ return 0;
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+}
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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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+
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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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--
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1.8.4
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