// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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>
*/
#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");
