/*
max6875.c - driver for MAX6874/MAX6875
Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
Based on i2c/chips/eeprom.c
The MAX6875 has two EEPROM sections: config and user.
At reset, the config EEPROM is read into the registers.
This driver make 3 binary files available in sysfs:
reg_config - direct access to the registers
eeprom_config - acesses configuration eeprom space
eeprom_user - free for application use
In our application, we put device serial & model numbers in user eeprom.
Notes:
1) The datasheet says that register 0x44 / EEPROM 0x8044 should NOT
be overwritten, so the driver explicitly prevents that.
2) It's a good idea to keep the config (0x45) locked in config EEPROM.
You can temporarily enable config writes by changing register 0x45.
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/config.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/i2c-sensor.h>
/* Addresses to scan */
/* No address scanned by default, as this could corrupt standard EEPROMS. */
static unsigned short normal_i2c[] = {I2C_CLIENT_END};
static unsigned int normal_isa[] = {I2C_CLIENT_ISA_END};
/* Insmod parameters */
SENSORS_INSMOD_1(max6875);
/* this param will prevent 'accidental' writes to the eeprom */
static int allow_write = 0;
module_param(allow_write, int, 0);
MODULE_PARM_DESC(allow_write,
"Enable write access:\n"
"*0: Read only\n"
" 1: Read/Write access");
/* The MAX6875 can only read/write 16 bytes at a time */
#define SLICE_SIZE 16
#define SLICE_BITS 4
/* CONFIG EEPROM is at addresses 0x8000 - 0x8045, registers are at 0 - 0x45 */
#define CONFIG_EEPROM_BASE 0x8000
#define CONFIG_EEPROM_SIZE 0x0046
#define CONFIG_EEPROM_SLICES 5
/* 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_BLOCK_WRITE 0x83
#define MAX6875_CMD_BLOCK_READ 0x84
#define MAX6875_CMD_REBOOT 0x88
enum max6875_area_type {
max6875_register_config=0,
max6875_eeprom_config,
max6875_eeprom_user,
max6857_max
};
struct eeprom_block {
enum max6875_area_type type;
u8 slices;
u32 size;
u32 valid;
u32 base;
unsigned long *updated;
u8 *data;
};
/* Each client has this additional data */
struct max6875_data {
struct i2c_client client;
struct semaphore update_lock;
struct eeprom_block blocks[max6857_max];
/* the above structs point into the arrays below */
u8 data[USER_EEPROM_SIZE + (CONFIG_EEPROM_SIZE*2)];
unsigned long last_updated[USER_EEPROM_SLICES + (CONFIG_EEPROM_SLICES*2)];
};
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 int max6875_update_slice(struct i2c_client *client,
struct eeprom_block *blk,
int slice)
{
struct max6875_data *data = i2c_get_clientdata(client);
int i, j, addr, count;
u8 rdbuf[SLICE_SIZE];
int retval = 0;
if (slice >= blk->slices)
return -1;
down(&data->update_lock);
if (!(blk->valid & (1 << slice)) ||
(jiffies - blk->updated[slice] > 300 * HZ) ||
(jiffies < blk->updated[slice])) {
dev_dbg(&client->dev, "Starting eeprom update, slice %u, base %u\n",
slice, blk->base);
addr = blk->base + (slice << SLICE_BITS);
count = blk->size - (slice << SLICE_BITS);
if (count > SLICE_SIZE) {
count = SLICE_SIZE;
}
/* Preset the read address */
if (addr < 0x100) {
/* select the register */
if (i2c_smbus_write_byte(client, addr & 0xFF)) {
dev_dbg(&client->dev, "max6875 register select has failed!\n");
retval = -1;
goto exit;
}
} else {
/* select the eeprom */
if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
dev_dbg(&client->dev, "max6875 address set has failed!\n");
retval = -1;
goto exit;
}
}
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
if (i2c_smbus_read_i2c_block_data(client, MAX6875_CMD_BLOCK_READ,
rdbuf) != SLICE_SIZE)
{
retval = -1;
goto exit;
}
memcpy(&blk->data[slice << SLICE_BITS], rdbuf, count);
} else {
for (i = 0; i < count; i++) {
j = i2c_smbus_read_byte(client);
if (j < 0)
{
retval = -1;
goto exit;
}
blk->data[(slice << SLICE_BITS) + i] = (u8) j;
}
}
blk->updated[slice] = jiffies;
blk->valid |= (1 << slice);
}
exit:
up(&data->update_lock);
return retval;
}
static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off, size_t count,
enum max6875_area_type area_type)
{
struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
struct max6875_data *data = i2c_get_clientdata(client);
struct eeprom_block *blk;
int slice;
blk = &data->blocks[area_type];
if (off > blk->size)
return 0;
if (off + count > blk->size)
count = blk->size - off;
/* Only refresh slices which contain requested bytes */
for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++)
max6875_update_slice(client, blk, slice);
memcpy(buf, &blk->data[off], count);
return count;
}
static ssize_t max6875_user_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_read(kobj, buf, off, count, max6875_eeprom_user);
}
static ssize_t max6875_config_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_read(kobj, buf, off, count, max6875_eeprom_config);
}
static ssize_t max6875_cfgreg_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_read(kobj, buf, off, count, max6875_register_config);
}
static ssize_t max6875_write(struct kobject *kobj, char *buf, loff_t off, size_t count,
enum max6875_area_type area_type)
{
struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
struct max6875_data *data = i2c_get_clientdata(client);
struct eeprom_block *blk;
int slice, addr, retval;
ssize_t sent = 0;
blk = &data->blocks[area_type];
if (off > blk->size)
return 0;
if ((off + count) > blk->size)
count = blk->size - off;
if (down_interruptible(&data->update_lock))
return -EAGAIN;
/* writing to a register is done with i2c_smbus_write_byte_data() */
if (blk->type == max6875_register_config) {
for (sent = 0; sent < count; sent++) {
addr = off + sent;
if (addr == 0x44)
continue;
retval = i2c_smbus_write_byte_data(client, addr, buf[sent]);
}
} else {
int cmd, val;
/* We are writing to EEPROM */
for (sent = 0; sent < count; sent++) {
addr = blk->base + off + sent;
cmd = addr >> 8;
val = (addr & 0xff) | (buf[sent] << 8); // reversed
if (addr == 0x8044)
continue;
retval = i2c_smbus_write_word_data(client, cmd, val);
if (retval) {
goto error_exit;
}
/* A write takes up to 11 ms */
msleep(11);
}
}
/* Invalidate the scratch buffer */
for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++)
blk->valid &= ~(1 << slice);
error_exit:
up(&data->update_lock);
return sent;
}
static ssize_t max6875_user_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_write(kobj, buf, off, count, max6875_eeprom_user);
}
static ssize_t max6875_config_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_write(kobj, buf, off, count, max6875_eeprom_config);
}
static ssize_t max6875_cfgreg_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
return max6875_write(kobj, buf, off, count, max6875_register_config);
}
static struct bin_attribute user_eeprom_attr = {
.attr = {
.name = "eeprom_user",
.mode = S_IRUGO | S_IWUSR | S_IWGRP,
.owner = THIS_MODULE,
},
.size = USER_EEPROM_SIZE,
.read = max6875_user_read,
.write = max6875_user_write,
};
static struct bin_attribute config_eeprom_attr = {
.attr = {
.name = "eeprom_config",
.mode = S_IRUGO | S_IWUSR,
.owner = THIS_MODULE,
},
.size = CONFIG_EEPROM_SIZE,
.read = max6875_config_read,
.write = max6875_config_write,
};
static struct bin_attribute config_register_attr = {
.attr = {
.name = "reg_config",
.mode = S_IRUGO | S_IWUSR,
.owner = THIS_MODULE,
},
.size = CONFIG_EEPROM_SIZE,
.read = max6875_cfgreg_read,
.write = max6875_cfgreg_write,
};
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 *new_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);
/* There are three ways we can read the EEPROM data:
(1) I2C block reads (faster, but unsupported by most adapters)
(2) Consecutive byte reads (100% overhead)
(3) Regular byte data reads (200% overhead)
The third method is not implemented by this driver because all
known adapters support at least the second. */
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA |
I2C_FUNC_SMBUS_BYTE |
I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
goto exit;
/* OK. For now, we presume we have a valid client. We now create the
client structure, even though we cannot fill it completely yet.
But it allows us to access eeprom_{read,write}_value. */
if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL))) {
err = -ENOMEM;
goto exit;
}
memset(data, 0, sizeof(struct max6875_data));
new_client = &data->client;
i2c_set_clientdata(new_client, data);
new_client->addr = address;
new_client->adapter = adapter;
new_client->driver = &max6875_driver;
new_client->flags = 0;
/* Setup the user section */
data->blocks[max6875_eeprom_user].type = max6875_eeprom_user;
data->blocks[max6875_eeprom_user].slices = USER_EEPROM_SLICES;
data->blocks[max6875_eeprom_user].size = USER_EEPROM_SIZE;
data->blocks[max6875_eeprom_user].base = USER_EEPROM_BASE;
data->blocks[max6875_eeprom_user].data = data->data;
data->blocks[max6875_eeprom_user].updated = data->last_updated;
/* Setup the config section */
data->blocks[max6875_eeprom_config].type = max6875_eeprom_config;
data->blocks[max6875_eeprom_config].slices = CONFIG_EEPROM_SLICES;
data->blocks[max6875_eeprom_config].size = CONFIG_EEPROM_SIZE;
data->blocks[max6875_eeprom_config].base = CONFIG_EEPROM_BASE;
data->blocks[max6875_eeprom_config].data = &data->data[USER_EEPROM_SIZE];
data->blocks[max6875_eeprom_config].updated = &data->last_updated[USER_EEPROM_SLICES];
/* Setup the register section */
data->blocks[max6875_register_config].type = max6875_register_config;
data->blocks[max6875_register_config].slices = CONFIG_EEPROM_SLICES;
data->blocks[max6875_register_config].size = CONFIG_EEPROM_SIZE;
data->blocks[max6875_register_config].base = 0;
data->blocks[max6875_register_config].data = &data->data[USER_EEPROM_SIZE+CONFIG_EEPROM_SIZE];
data->blocks[max6875_register_config].updated = &data->last_updated[USER_EEPROM_SLICES+CONFIG_EEPROM_SLICES];
/* Init the data */
memset(data->data, 0xff, sizeof(data->data));
/* Fill in the remaining client fields */
strlcpy(new_client->name, "max6875", I2C_NAME_SIZE);
init_MUTEX(&data->update_lock);
/* Verify that the chip is really what we think it is */
if ((max6875_update_slice(new_client, &data->blocks[max6875_eeprom_config], 4) < 0) ||
(max6875_update_slice(new_client, &data->blocks[max6875_register_config], 4) < 0))
goto exit_kfree;
/* 0x41,0x42 must be zero and 0x40 must match in eeprom and registers */
if ((data->blocks[max6875_eeprom_config].data[0x41] != 0) ||
(data->blocks[max6875_eeprom_config].data[0x42] != 0) ||
(data->blocks[max6875_register_config].data[0x41] != 0) ||
(data->blocks[max6875_register_config].data[0x42] != 0) ||
(data->blocks[max6875_eeprom_config].data[0x40] !=
data->blocks[max6875_register_config].data[0x40]))
goto exit_kfree;
/* Tell the I2C layer a new client has arrived */
if ((err = i2c_attach_client(new_client)))
goto exit_kfree;
/* create the sysfs eeprom files with the correct permissions */
if (allow_write == 0) {
user_eeprom_attr.attr.mode &= ~S_IWUGO;
user_eeprom_attr.write = NULL;
config_eeprom_attr.attr.mode &= ~S_IWUGO;
config_eeprom_attr.write = NULL;
config_register_attr.attr.mode &= ~S_IWUGO;
config_register_attr.write = NULL;
}
sysfs_create_bin_file(&new_client->dev.kobj, &user_eeprom_attr);
sysfs_create_bin_file(&new_client->dev.kobj, &config_eeprom_attr);
sysfs_create_bin_file(&new_client->dev.kobj, &config_register_attr);
return 0;
exit_kfree:
kfree(data);
exit:
return err;
}
static int max6875_detach_client(struct i2c_client *client)
{
int err;
err = i2c_detach_client(client);
if (err) {
dev_err(&client->dev, "Client deregistration failed, client not detached.\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);
