diff options
Diffstat (limited to 'drivers/misc/eeprom/eeprom.c')
| -rw-r--r-- | drivers/misc/eeprom/eeprom.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/misc/eeprom/eeprom.c b/drivers/misc/eeprom/eeprom.c new file mode 100644 index 000000000..60e3d91b5 --- /dev/null +++ b/drivers/misc/eeprom/eeprom.c @@ -0,0 +1,222 @@ +/* + * Copyright (C) 1998, 1999 Frodo Looijaard <frodol@dds.nl> and + * Philip Edelbrock <phil@netroedge.com> + * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com> + * Copyright (C) 2003 IBM Corp. + * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de> + * + * 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. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/capability.h> +#include <linux/jiffies.h> +#include <linux/i2c.h> +#include <linux/mutex.h> + +/* Addresses to scan */ +static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54, + 0x55, 0x56, 0x57, I2C_CLIENT_END }; + + +/* Size of EEPROM in bytes */ +#define EEPROM_SIZE 256 + +/* possible types of eeprom devices */ +enum eeprom_nature { + UNKNOWN, + VAIO, +}; + +/* Each client has this additional data */ +struct eeprom_data { + struct mutex update_lock; + u8 valid; /* bitfield, bit!=0 if slice is valid */ + unsigned long last_updated[8]; /* In jiffies, 8 slices */ + u8 data[EEPROM_SIZE]; /* Register values */ + enum eeprom_nature nature; +}; + + +static void eeprom_update_client(struct i2c_client *client, u8 slice) +{ + struct eeprom_data *data = i2c_get_clientdata(client); + int i; + + mutex_lock(&data->update_lock); + + if (!(data->valid & (1 << slice)) || + time_after(jiffies, data->last_updated[slice] + 300 * HZ)) { + dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice); + + if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { + for (i = slice << 5; i < (slice + 1) << 5; i += 32) + if (i2c_smbus_read_i2c_block_data(client, i, + 32, data->data + i) + != 32) + goto exit; + } else { + for (i = slice << 5; i < (slice + 1) << 5; i += 2) { + int word = i2c_smbus_read_word_data(client, i); + if (word < 0) + goto exit; + data->data[i] = word & 0xff; + data->data[i + 1] = word >> 8; + } + } + data->last_updated[slice] = jiffies; + data->valid |= (1 << slice); + } +exit: + mutex_unlock(&data->update_lock); +} + +static ssize_t eeprom_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t off, size_t count) +{ + struct i2c_client *client = to_i2c_client(kobj_to_dev(kobj)); + struct eeprom_data *data = i2c_get_clientdata(client); + u8 slice; + + /* Only refresh slices which contain requested bytes */ + for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++) + eeprom_update_client(client, slice); + + /* Hide Vaio private settings to regular users: + - BIOS passwords: bytes 0x00 to 0x0f + - UUID: bytes 0x10 to 0x1f + - Serial number: 0xc0 to 0xdf */ + if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) { + int i; + + for (i = 0; i < count; i++) { + if ((off + i <= 0x1f) || + (off + i >= 0xc0 && off + i <= 0xdf)) + buf[i] = 0; + else + buf[i] = data->data[off + i]; + } + } else { + memcpy(buf, &data->data[off], count); + } + + return count; +} + +static const struct bin_attribute eeprom_attr = { + .attr = { + .name = "eeprom", + .mode = S_IRUGO, + }, + .size = EEPROM_SIZE, + .read = eeprom_read, +}; + +/* Return 0 if detection is successful, -ENODEV otherwise */ +static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info) +{ + struct i2c_adapter *adapter = client->adapter; + + /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all + addresses 0x50-0x57, but we only care about 0x50. So decline + attaching to addresses >= 0x51 on DDC buses */ + if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51) + return -ENODEV; + + /* There are four ways we can read the EEPROM data: + (1) I2C block reads (faster, but unsupported by most adapters) + (2) Word reads (128% overhead) + (3) Consecutive byte reads (88% overhead, unsafe) + (4) Regular byte data reads (265% overhead) + The third and fourth methods are not implemented by this driver + because all known adapters support one of the first two. */ + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA) + && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) + return -ENODEV; + + strlcpy(info->type, "eeprom", I2C_NAME_SIZE); + + return 0; +} + +static int eeprom_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct i2c_adapter *adapter = client->adapter; + struct eeprom_data *data; + + data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data), + GFP_KERNEL); + if (!data) + return -ENOMEM; + + memset(data->data, 0xff, EEPROM_SIZE); + i2c_set_clientdata(client, data); + mutex_init(&data->update_lock); + data->nature = UNKNOWN; + + /* Detect the Vaio nature of EEPROMs. + We use the "PCG-" or "VGN-" prefix as the signature. */ + if (client->addr == 0x57 + && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) { + char name[4]; + + name[0] = i2c_smbus_read_byte_data(client, 0x80); + name[1] = i2c_smbus_read_byte_data(client, 0x81); + name[2] = i2c_smbus_read_byte_data(client, 0x82); + name[3] = i2c_smbus_read_byte_data(client, 0x83); + + if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) { + dev_info(&client->dev, "Vaio EEPROM detected, " + "enabling privacy protection\n"); + data->nature = VAIO; + } + } + + /* create the sysfs eeprom file */ + return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr); +} + +static int eeprom_remove(struct i2c_client *client) +{ + sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr); + + return 0; +} + +static const struct i2c_device_id eeprom_id[] = { + { "eeprom", 0 }, + { } +}; + +static struct i2c_driver eeprom_driver = { + .driver = { + .name = "eeprom", + }, + .probe = eeprom_probe, + .remove = eeprom_remove, + .id_table = eeprom_id, + + .class = I2C_CLASS_DDC | I2C_CLASS_SPD, + .detect = eeprom_detect, + .address_list = normal_i2c, +}; + +module_i2c_driver(eeprom_driver); + +MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " + "Philip Edelbrock <phil@netroedge.com> and " + "Greg Kroah-Hartman <greg@kroah.com>"); +MODULE_DESCRIPTION("I2C EEPROM driver"); +MODULE_LICENSE("GPL"); |