270 lines
6.9 KiB
C
270 lines
6.9 KiB
C
/*
|
|
max6875.c - driver for MAX6874/MAX6875
|
|
|
|
Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
|
|
|
|
Based on i2c/chips/eeprom.c
|
|
|
|
The MAX6875 has a bank of registers and two banks of EEPROM.
|
|
Address ranges are defined as follows:
|
|
* 0x0000 - 0x0046 = configuration registers
|
|
* 0x8000 - 0x8046 = configuration EEPROM
|
|
* 0x8100 - 0x82FF = user EEPROM
|
|
|
|
This driver makes the user EEPROM available for read.
|
|
|
|
The registers & config EEPROM should be accessed via i2c-dev.
|
|
|
|
The MAX6875 ignores the lowest address bit, so each chip responds to
|
|
two addresses - 0x50/0x51 and 0x52/0x53.
|
|
|
|
Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
|
|
address, so this driver is destructive if loaded for the wrong EEPROM chip.
|
|
|
|
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; version 2 of the License.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/i2c-sensor.h>
|
|
#include <asm/semaphore.h>
|
|
|
|
/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
|
|
static unsigned short normal_i2c[] = {I2C_CLIENT_END};
|
|
|
|
/* Insmod parameters */
|
|
SENSORS_INSMOD_1(max6875);
|
|
|
|
/* The MAX6875 can only read/write 16 bytes at a time */
|
|
#define SLICE_SIZE 16
|
|
#define SLICE_BITS 4
|
|
|
|
/* USER EEPROM is at addresses 0x8100 - 0x82FF */
|
|
#define USER_EEPROM_BASE 0x8100
|
|
#define USER_EEPROM_SIZE 0x0200
|
|
#define USER_EEPROM_SLICES 32
|
|
|
|
/* MAX6875 commands */
|
|
#define MAX6875_CMD_BLK_READ 0x84
|
|
|
|
/* Each client has this additional data */
|
|
struct max6875_data {
|
|
struct i2c_client client;
|
|
struct semaphore update_lock;
|
|
|
|
u32 valid;
|
|
u8 data[USER_EEPROM_SIZE];
|
|
unsigned long last_updated[USER_EEPROM_SLICES];
|
|
};
|
|
|
|
static int max6875_attach_adapter(struct i2c_adapter *adapter);
|
|
static int max6875_detect(struct i2c_adapter *adapter, int address, int kind);
|
|
static int max6875_detach_client(struct i2c_client *client);
|
|
|
|
/* This is the driver that will be inserted */
|
|
static struct i2c_driver max6875_driver = {
|
|
.owner = THIS_MODULE,
|
|
.name = "max6875",
|
|
.flags = I2C_DF_NOTIFY,
|
|
.attach_adapter = max6875_attach_adapter,
|
|
.detach_client = max6875_detach_client,
|
|
};
|
|
|
|
static void max6875_update_slice(struct i2c_client *client, int slice)
|
|
{
|
|
struct max6875_data *data = i2c_get_clientdata(client);
|
|
int i, j, addr;
|
|
u8 *buf;
|
|
|
|
if (slice >= USER_EEPROM_SLICES)
|
|
return;
|
|
|
|
down(&data->update_lock);
|
|
|
|
buf = &data->data[slice << SLICE_BITS];
|
|
|
|
if (!(data->valid & (1 << slice)) ||
|
|
time_after(jiffies, data->last_updated[slice])) {
|
|
|
|
dev_dbg(&client->dev, "Starting update of slice %u\n", slice);
|
|
|
|
data->valid &= ~(1 << slice);
|
|
|
|
addr = USER_EEPROM_BASE + (slice << SLICE_BITS);
|
|
|
|
/* select the eeprom address */
|
|
if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
|
|
dev_err(&client->dev, "address set failed\n");
|
|
goto exit_up;
|
|
}
|
|
|
|
if (i2c_check_functionality(client->adapter,
|
|
I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
|
|
if (i2c_smbus_read_i2c_block_data(client,
|
|
MAX6875_CMD_BLK_READ,
|
|
buf) != SLICE_SIZE) {
|
|
goto exit_up;
|
|
}
|
|
} else {
|
|
for (i = 0; i < SLICE_SIZE; i++) {
|
|
j = i2c_smbus_read_byte(client);
|
|
if (j < 0) {
|
|
goto exit_up;
|
|
}
|
|
buf[i] = j;
|
|
}
|
|
}
|
|
data->last_updated[slice] = jiffies;
|
|
data->valid |= (1 << slice);
|
|
}
|
|
exit_up:
|
|
up(&data->update_lock);
|
|
}
|
|
|
|
static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off,
|
|
size_t count)
|
|
{
|
|
struct i2c_client *client = kobj_to_i2c_client(kobj);
|
|
struct max6875_data *data = i2c_get_clientdata(client);
|
|
int slice, max_slice;
|
|
|
|
if (off > USER_EEPROM_SIZE)
|
|
return 0;
|
|
|
|
if (off + count > USER_EEPROM_SIZE)
|
|
count = USER_EEPROM_SIZE - off;
|
|
|
|
/* refresh slices which contain requested bytes */
|
|
max_slice = (off + count - 1) >> SLICE_BITS;
|
|
for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
|
|
max6875_update_slice(client, slice);
|
|
|
|
memcpy(buf, &data->data[off], count);
|
|
|
|
return count;
|
|
}
|
|
|
|
static struct bin_attribute user_eeprom_attr = {
|
|
.attr = {
|
|
.name = "eeprom",
|
|
.mode = S_IRUGO,
|
|
.owner = THIS_MODULE,
|
|
},
|
|
.size = USER_EEPROM_SIZE,
|
|
.read = max6875_read,
|
|
};
|
|
|
|
static int max6875_attach_adapter(struct i2c_adapter *adapter)
|
|
{
|
|
return i2c_detect(adapter, &addr_data, max6875_detect);
|
|
}
|
|
|
|
/* This function is called by i2c_detect */
|
|
static int max6875_detect(struct i2c_adapter *adapter, int address, int kind)
|
|
{
|
|
struct i2c_client *real_client;
|
|
struct i2c_client *fake_client;
|
|
struct max6875_data *data;
|
|
int err = 0;
|
|
|
|
/* Prevent 24rf08 corruption (in case of user error) */
|
|
if (kind < 0)
|
|
i2c_smbus_xfer(adapter, address, 0, 0, 0,
|
|
I2C_SMBUS_QUICK, NULL);
|
|
|
|
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
|
|
| I2C_FUNC_SMBUS_READ_BYTE))
|
|
return 0;
|
|
|
|
/* Only check even addresses */
|
|
if (address & 1)
|
|
return 0;
|
|
|
|
if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL)))
|
|
return -ENOMEM;
|
|
memset(data, 0, sizeof(struct max6875_data));
|
|
|
|
/* A fake client is created on the odd address */
|
|
if (!(fake_client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
|
|
err = -ENOMEM;
|
|
goto exit_kfree1;
|
|
}
|
|
memset(fake_client, 0, sizeof(struct i2c_client));
|
|
|
|
/* Init real i2c_client */
|
|
real_client = &data->client;
|
|
i2c_set_clientdata(real_client, data);
|
|
real_client->addr = address;
|
|
real_client->adapter = adapter;
|
|
real_client->driver = &max6875_driver;
|
|
real_client->flags = 0;
|
|
strlcpy(real_client->name, "max6875", I2C_NAME_SIZE);
|
|
init_MUTEX(&data->update_lock);
|
|
|
|
/* Init fake client data */
|
|
/* set the client data to the i2c_client so that it will get freed */
|
|
i2c_set_clientdata(fake_client, fake_client);
|
|
fake_client->addr = address | 1;
|
|
fake_client->adapter = adapter;
|
|
fake_client->driver = &max6875_driver;
|
|
fake_client->flags = 0;
|
|
strlcpy(fake_client->name, "max6875 subclient", I2C_NAME_SIZE);
|
|
|
|
/* Prevent 24RF08 corruption (in case of user error) */
|
|
i2c_smbus_write_quick(real_client, 0);
|
|
|
|
if ((err = i2c_attach_client(real_client)) != 0)
|
|
goto exit_kfree2;
|
|
|
|
if ((err = i2c_attach_client(fake_client)) != 0)
|
|
goto exit_detach;
|
|
|
|
sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr);
|
|
|
|
return 0;
|
|
|
|
exit_detach:
|
|
i2c_detach_client(real_client);
|
|
exit_kfree2:
|
|
kfree(fake_client);
|
|
exit_kfree1:
|
|
kfree(data);
|
|
return err;
|
|
}
|
|
|
|
static int max6875_detach_client(struct i2c_client *client)
|
|
{
|
|
int err;
|
|
|
|
err = i2c_detach_client(client);
|
|
if (err) {
|
|
dev_err(&client->dev, "i2c_detach_client() failed\n");
|
|
return err;
|
|
}
|
|
kfree(i2c_get_clientdata(client));
|
|
return 0;
|
|
}
|
|
|
|
static int __init max6875_init(void)
|
|
{
|
|
return i2c_add_driver(&max6875_driver);
|
|
}
|
|
|
|
static void __exit max6875_exit(void)
|
|
{
|
|
i2c_del_driver(&max6875_driver);
|
|
}
|
|
|
|
|
|
MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
|
|
MODULE_DESCRIPTION("MAX6875 driver");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_init(max6875_init);
|
|
module_exit(max6875_exit);
|