Hi Oliver, Le 17/05/2013 15:35, Oliver Schinagl a écrit : > From: Oliver Schinagl <oli...@schinagl.nl> > > Allwinner has electric fuses (efuse) on their line of chips. This driver > reads those fuses and exports them as a sysfs node. Also a symbol is exported > for in-kernel useage. > > While initially these fuses are used to somewhat determin the chipID, these > appear to be writeable by the user and thus can be used for other purpouses. > For example storing a 128 bit root key, a unique serial number, which could > then even be used as a MAC address. > > Because writing to e-fuses can be potentially dangerous, and are certainly > not as often writable (if at all) as flash memory, these shouldn't be easily > changeable, hence only a read-only mode. An offline tool to write the fuses > is in the works. > > Currently supported are the following known chips: > Allwinner sun4i (A10) > Allwinner sun5i (A10s A13) > Allwinner sun6i (A31, A31s) > Allwinner sun7i (A20)
Since I don't think those patches have been tested on sun6i/sun7i, and that there's not even kernel support for those, maybe it's not worth mentionning them? > > Signed-off-by: Oliver Schinagl <oli...@schinagl.nl> > --- > drivers/misc/eeprom/Kconfig | 19 ++++ > drivers/misc/eeprom/Makefile | 1 + > drivers/misc/eeprom/sunxi_sid.c | 218 > ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 238 insertions(+) > create mode 100644 drivers/misc/eeprom/sunxi_sid.c > > diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig > index 04f2e1f..c9ddda5 100644 > --- a/drivers/misc/eeprom/Kconfig > +++ b/drivers/misc/eeprom/Kconfig > @@ -96,4 +96,23 @@ config EEPROM_DIGSY_MTC_CFG > > If unsure, say N. > > +config EEPROM_SUNXI_SID > + tristate "Allwinner sunxi security ID support" > + depends on ARCH_SUNXI && SYSFS > + help > + This is a driver for the 'security ID' available on various Allwinner > + devices. Currently supported are: > + sun4i (A10) > + sun5i (A10s, A12, A13) > + sun6i (A31) > + sun7i (A20) Same things here. > + > + Due to the potential risks involved with changing e-fuses, > + this driver is read-only > + > + For more information visit http://linux-sunxi.org/SID > + > + This driver can also be built as a module. If so, the module > + will be called sunxi_sid. > + > endmenu > diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile > index fc1e81d..9507aec 100644 > --- a/drivers/misc/eeprom/Makefile > +++ b/drivers/misc/eeprom/Makefile > @@ -4,4 +4,5 @@ obj-$(CONFIG_EEPROM_LEGACY) += eeprom.o > obj-$(CONFIG_EEPROM_MAX6875) += max6875.o > obj-$(CONFIG_EEPROM_93CX6) += eeprom_93cx6.o > obj-$(CONFIG_EEPROM_93XX46) += eeprom_93xx46.o > +obj-$(CONFIG_EEPROM_SUNXI_SID) += sunxi_sid.o > obj-$(CONFIG_EEPROM_DIGSY_MTC_CFG) += digsy_mtc_eeprom.o > diff --git a/drivers/misc/eeprom/sunxi_sid.c b/drivers/misc/eeprom/sunxi_sid.c > new file mode 100644 > index 0000000..953f137 > --- /dev/null > +++ b/drivers/misc/eeprom/sunxi_sid.c > @@ -0,0 +1,218 @@ > +/* > + * Copyright (c) 2013 Oliver Schinagl > + * http://www.linux-sunxi.org > + * > + * Oliver Schinagl <oli...@schinagl.nl> > + * > + * 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, a 128 bit eeprom, in chunks > + * of 8 bytes. 16 bytes or 8 bits? because 8 bytes != 128 bits. > + */ > + > +#include <linux/compiler.h> > +#include <linux/device.h> > +#include <linux/errno.h> > +#include <linux/export.h> > +#include <linux/fs.h> > +#include <linux/init.h> > +#include <linux/io.h> > +#include <linux/kobject.h> > +#include <linux/module.h> > +#include <linux/of_address.h> > +#include <linux/platform_device.h> > +#include <linux/stat.h> > +#include <linux/sysfs.h> > +#include <linux/types.h> > + > + > +#define DRV_NAME "sunxi-sid" > +#define DRV_VERSION "1.0" > + > +/* Register offsets */ > +#define SUNXI_SID_KEY0 0x00 > +#define SUNXI_SID_KEY1 0x04 > +#define SUNXI_SID_KEY2 0x08 > +#define SUNXI_SID_KEY3 0x0c > + > +/* There are 4 32-bit keys */ > +#define SUNXI_SID_KEYS 4 > +/* and 4 32-bit keys per 32-bit key */ The comment is wrong here. > +#define SUNXI_SID_SIZE (SUNXI_SID_KEYS * 4) > + > +#if (SUNXI_SID_SIZE > PAGE_SIZE) > +#error "SUNXI_SID_SIZE is larger then the target's PAGE_SIZE, ENOMEM." > +#endif Hmmmm, I don't follow you here, what's the relation between your driver and PAGE_SIZE? > + > +static u8 keys_lut[] = { > + SUNXI_SID_KEY0, > + SUNXI_SID_KEY1, > + SUNXI_SID_KEY2, > + SUNXI_SID_KEY3, > +}; > + > +struct sid_priv { > + void __iomem *sid_base; > +}; > + > +struct sid_priv *p; What's the point of having a structure here? And why putting a global value, !static, with a generic name, while you could have an instance-specific one? struct file has a private_data field, use it. > + > + > +/* We read the entire key, using a look up table. Returned is only the > + * requested byte. This is of course slower then it could be and uses 4 times > + * more reads as needed but keeps code a little simpler. > + */ > +u8 sunxi_sid_read_byte(const int key) > +{ > + u32 sid_key; > + u8 ret; > + > + ret = 0; > + if (likely((key <= SUNXI_SID_SIZE))) { > + sid_key = ioread32(p->sid_base + keys_lut[key >> 2]); > + switch (key % 4) { > + case 0: > + ret = (sid_key >> 24) & 0xff; > + break; > + case 1: > + ret = (sid_key >> 16) & 0xff; > + break; > + case 2: > + ret = (sid_key >> 8) & 0xff; > + break; > + case 3: > + ret = sid_key & 0xff; > + break; > + } > + } Come on, you can do better. This lookup table is useless. Also, why the first key is the one with the MSBs? I'd expect that the key 0 is the one holding the LSBs. > + > + return ret; > +} > + > +static ssize_t sid_read(struct file *fd, struct kobject *kobj, > + struct bin_attribute *attr, char *buf, > + loff_t pos, size_t size) > +{ > + ssize_t ret; > + struct device *dev; > + struct sid_priv *priv; > + int i; > + > + ret = -EPERM; > + dev = kobj_to_dev(kobj); > + priv = dev_get_drvdata(dev); > + > + if ((likely(size > 0)) && ((size + pos) <= SUNXI_SID_SIZE)) { > + for (i = 0; i < size; i++) { > + buf[i] = sunxi_sid_read_byte(pos + i); > + } > + if (i < PAGE_SIZE) { > + buf[i] = '\0'; > + ret = (ssize_t)size; > + } else { > + ret = -ENOMEM; > + } Hmmmm, what? Why returning \0 here? It's not a string, it's binary data. What's the relation with PAGE_SIZE again? Just return the number of bytes read, that's it. > + } else { > + buf[0] = '\0'; > + ret = 0; > + } > + > + return ret; > +} > + > +static struct of_device_id sid_of_match[] = { > + { > + .compatible = "allwinner,sun4i-sid", > + }, > + {/* sentinel */} > +}; > +MODULE_DEVICE_TABLE(of, sid_of_match); > + > +static struct bin_attribute sid_bin_attr = { > + .attr = { > + .name = "key", > + .mode = S_IRUGO, > + }, > + .size = SUNXI_SID_SIZE, > + .read = sid_read, > +}; > + > +static int sid_remove(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct sid_priv *priv; > + > + priv = dev_get_drvdata(dev); > + device_remove_bin_file(dev, &sid_bin_attr); > + iounmap(priv->sid_base); > + devm_kfree(dev, priv); > + return 0; > +} > + > +static int __init sid_probe(struct platform_device *pdev) > +{ > + int ret; > + struct device *dev = &pdev->dev; > + struct sid_priv *priv; > + > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > + p = priv; > + > + dev_set_drvdata(dev, priv); > + > + if (!priv) { > + dev_err(dev, "Unable to allocate device private data\n"); > + ret = -ENOMEM; > + goto exit; > + } Isn't it a bit weird to check for the memory allocation after using the variable. Also, you don't really need the dev_err, since if the kernel fails to allocate some memory, it will tell you anyway. > + priv->sid_base = of_iomap(dev->of_node, 0); > + if (!priv->sid_base) { > + dev_err(dev, "Unable to map memory region\n"); > + ret = -ENOMEM; > + goto exit_free; > + } > + > + ret = device_create_bin_file(dev, &sid_bin_attr); > + if (ret) { > + dev_err(dev, "Unable to create sysfs bin entry\n"); > + goto exit_unmap; > + } Hmmm, maybe it's not worth all these gotos just for an iounmap, I'd probably return right away, but that's your call. > + dev_info(dev, "Sunxi security ID driver loaded successfully.\n"); > + > + return 0; > + > + > +exit_unmap: > + iounmap(priv->sid_base); > +exit_free: > + devm_kfree(dev, priv); > +exit: > + return ret; > +} > + > +static struct platform_driver sid_driver = { > + .probe = sid_probe, > + .remove = sid_remove, > + .driver = { > + .name = DRV_NAME, > + .owner = THIS_MODULE, > + .of_match_table = sid_of_match, > + }, > +}; > +module_platform_driver(sid_driver); > + > + > +MODULE_AUTHOR("Oliver Schinagl <oli...@schinagl.nl>"); > +MODULE_DESCRIPTION("Allwinner sunxi security id driver"); > +MODULE_VERSION(DRV_VERSION); > +MODULE_LICENSE("GPL"); > Thanks for this driver! Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
