linux/drivers/i2c/chips/max6875.c
Jean Delvare bd8d421f7c i2c: Convert the max6875 driver to a new-style i2c driver
The new-style max6875 driver implements the optional detect() callback
to cover the use cases of the legacy driver. I'm curious if anyone
really needs this though, so it might be removed in the feature.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-16 19:30:07 +02:00

246 lines
5.8 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/mutex.h>
/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
/* Insmod parameters */
I2C_CLIENT_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 *fake_client;
struct mutex update_lock;
u32 valid;
u8 data[USER_EEPROM_SIZE];
unsigned long last_updated[USER_EEPROM_SLICES];
};
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;
mutex_lock(&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,
SLICE_SIZE,
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:
mutex_unlock(&data->update_lock);
}
static ssize_t max6875_read(struct kobject *kobj,
struct bin_attribute *bin_attr,
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,
},
.size = USER_EEPROM_SIZE,
.read = max6875_read,
};
/* Return 0 if detection is successful, -ENODEV otherwise */
static int max6875_detect(struct i2c_client *client, int kind,
struct i2c_board_info *info)
{
struct i2c_adapter *adapter = client->adapter;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
| I2C_FUNC_SMBUS_READ_BYTE))
return -ENODEV;
/* Only check even addresses */
if (client->addr & 1)
return -ENODEV;
strlcpy(info->type, "max6875", I2C_NAME_SIZE);
return 0;
}
static int max6875_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct max6875_data *data;
int err;
if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
return -ENOMEM;
/* A fake client is created on the odd address */
data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1);
if (!data->fake_client) {
err = -ENOMEM;
goto exit_kfree;
}
/* Init real i2c_client */
i2c_set_clientdata(client, data);
mutex_init(&data->update_lock);
err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr);
if (err)
goto exit_remove_fake;
return 0;
exit_remove_fake:
i2c_unregister_device(data->fake_client);
exit_kfree:
kfree(data);
return err;
}
static int max6875_remove(struct i2c_client *client)
{
struct max6875_data *data = i2c_get_clientdata(client);
i2c_unregister_device(data->fake_client);
sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
kfree(data);
return 0;
}
static const struct i2c_device_id max6875_id[] = {
{ "max6875", 0 },
{ }
};
static struct i2c_driver max6875_driver = {
.driver = {
.name = "max6875",
},
.probe = max6875_probe,
.remove = max6875_remove,
.id_table = max6875_id,
.detect = max6875_detect,
.address_data = &addr_data,
};
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);