273 lines
6.8 KiB
C
273 lines
6.8 KiB
C
/*
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max6875.c - driver for MAX6874/MAX6875
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Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
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Based on i2c/chips/eeprom.c
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The MAX6875 has a bank of registers and two banks of EEPROM.
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Address ranges are defined as follows:
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* 0x0000 - 0x0046 = configuration registers
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* 0x8000 - 0x8046 = configuration EEPROM
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* 0x8100 - 0x82FF = user EEPROM
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This driver makes the user EEPROM available for read.
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The registers & config EEPROM should be accessed via i2c-dev.
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The MAX6875 ignores the lowest address bit, so each chip responds to
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two addresses - 0x50/0x51 and 0x52/0x53.
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Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
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address, so this driver is destructive if loaded for the wrong EEPROM chip.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/mutex.h>
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/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
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static unsigned short normal_i2c[] = {I2C_CLIENT_END};
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/* Insmod parameters */
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I2C_CLIENT_INSMOD_1(max6875);
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/* The MAX6875 can only read/write 16 bytes at a time */
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#define SLICE_SIZE 16
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#define SLICE_BITS 4
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/* USER EEPROM is at addresses 0x8100 - 0x82FF */
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#define USER_EEPROM_BASE 0x8100
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#define USER_EEPROM_SIZE 0x0200
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#define USER_EEPROM_SLICES 32
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/* MAX6875 commands */
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#define MAX6875_CMD_BLK_READ 0x84
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/* Each client has this additional data */
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struct max6875_data {
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struct i2c_client client;
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struct mutex update_lock;
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u32 valid;
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u8 data[USER_EEPROM_SIZE];
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unsigned long last_updated[USER_EEPROM_SLICES];
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};
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static int max6875_attach_adapter(struct i2c_adapter *adapter);
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static int max6875_detect(struct i2c_adapter *adapter, int address, int kind);
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static int max6875_detach_client(struct i2c_client *client);
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/* This is the driver that will be inserted */
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static struct i2c_driver max6875_driver = {
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.driver = {
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.name = "max6875",
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},
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.attach_adapter = max6875_attach_adapter,
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.detach_client = max6875_detach_client,
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};
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static void max6875_update_slice(struct i2c_client *client, int slice)
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{
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struct max6875_data *data = i2c_get_clientdata(client);
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int i, j, addr;
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u8 *buf;
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if (slice >= USER_EEPROM_SLICES)
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return;
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mutex_lock(&data->update_lock);
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buf = &data->data[slice << SLICE_BITS];
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if (!(data->valid & (1 << slice)) ||
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time_after(jiffies, data->last_updated[slice])) {
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dev_dbg(&client->dev, "Starting update of slice %u\n", slice);
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data->valid &= ~(1 << slice);
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addr = USER_EEPROM_BASE + (slice << SLICE_BITS);
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/* select the eeprom address */
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if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
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dev_err(&client->dev, "address set failed\n");
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goto exit_up;
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}
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if (i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
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if (i2c_smbus_read_i2c_block_data(client,
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MAX6875_CMD_BLK_READ,
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buf) != SLICE_SIZE) {
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goto exit_up;
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}
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} else {
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for (i = 0; i < SLICE_SIZE; i++) {
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j = i2c_smbus_read_byte(client);
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if (j < 0) {
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goto exit_up;
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}
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buf[i] = j;
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}
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}
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data->last_updated[slice] = jiffies;
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data->valid |= (1 << slice);
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}
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exit_up:
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mutex_unlock(&data->update_lock);
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}
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static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off,
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size_t count)
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{
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struct i2c_client *client = kobj_to_i2c_client(kobj);
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struct max6875_data *data = i2c_get_clientdata(client);
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int slice, max_slice;
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if (off > USER_EEPROM_SIZE)
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return 0;
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if (off + count > USER_EEPROM_SIZE)
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count = USER_EEPROM_SIZE - off;
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/* refresh slices which contain requested bytes */
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max_slice = (off + count - 1) >> SLICE_BITS;
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for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
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max6875_update_slice(client, slice);
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memcpy(buf, &data->data[off], count);
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return count;
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}
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static struct bin_attribute user_eeprom_attr = {
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.attr = {
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.name = "eeprom",
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.mode = S_IRUGO,
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.owner = THIS_MODULE,
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},
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.size = USER_EEPROM_SIZE,
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.read = max6875_read,
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};
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static int max6875_attach_adapter(struct i2c_adapter *adapter)
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{
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return i2c_probe(adapter, &addr_data, max6875_detect);
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}
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/* This function is called by i2c_probe */
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static int max6875_detect(struct i2c_adapter *adapter, int address, int kind)
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{
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struct i2c_client *real_client;
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struct i2c_client *fake_client;
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struct max6875_data *data;
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int err = 0;
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
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| I2C_FUNC_SMBUS_READ_BYTE))
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return 0;
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/* Only check even addresses */
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if (address & 1)
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return 0;
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if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
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return -ENOMEM;
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/* A fake client is created on the odd address */
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if (!(fake_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
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err = -ENOMEM;
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goto exit_kfree1;
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}
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/* Init real i2c_client */
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real_client = &data->client;
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i2c_set_clientdata(real_client, data);
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real_client->addr = address;
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real_client->adapter = adapter;
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real_client->driver = &max6875_driver;
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real_client->flags = 0;
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strlcpy(real_client->name, "max6875", I2C_NAME_SIZE);
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mutex_init(&data->update_lock);
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/* Init fake client data */
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i2c_set_clientdata(fake_client, NULL);
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fake_client->addr = address | 1;
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fake_client->adapter = adapter;
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fake_client->driver = &max6875_driver;
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fake_client->flags = 0;
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strlcpy(fake_client->name, "max6875 subclient", I2C_NAME_SIZE);
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/* Prevent 24RF08 corruption (in case of user error) */
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i2c_smbus_write_quick(real_client, 0);
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if ((err = i2c_attach_client(real_client)) != 0)
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goto exit_kfree2;
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if ((err = i2c_attach_client(fake_client)) != 0)
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goto exit_detach1;
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err = sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr);
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if (err)
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goto exit_detach2;
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return 0;
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exit_detach2:
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i2c_detach_client(fake_client);
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exit_detach1:
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i2c_detach_client(real_client);
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exit_kfree2:
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kfree(fake_client);
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exit_kfree1:
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kfree(data);
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return err;
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}
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/* Will be called for both the real client and the fake client */
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static int max6875_detach_client(struct i2c_client *client)
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{
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int err;
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struct max6875_data *data = i2c_get_clientdata(client);
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/* data is NULL for the fake client */
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if (data)
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sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
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err = i2c_detach_client(client);
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if (err)
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return err;
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if (data) /* real client */
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kfree(data);
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else /* fake client */
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kfree(client);
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return 0;
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}
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static int __init max6875_init(void)
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{
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return i2c_add_driver(&max6875_driver);
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}
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static void __exit max6875_exit(void)
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{
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i2c_del_driver(&max6875_driver);
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}
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MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
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MODULE_DESCRIPTION("MAX6875 driver");
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MODULE_LICENSE("GPL");
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module_init(max6875_init);
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module_exit(max6875_exit);
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