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BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -04001/*
Arce, Abraham6858d492010-05-13 15:05:47 -05002 * max6875.c - driver for MAX6874/MAX6875
3 *
4 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
5 *
6 * Based on eeprom.c
7 *
8 * The MAX6875 has a bank of registers and two banks of EEPROM.
9 * Address ranges are defined as follows:
10 * * 0x0000 - 0x0046 = configuration registers
11 * * 0x8000 - 0x8046 = configuration EEPROM
12 * * 0x8100 - 0x82FF = user EEPROM
13 *
14 * This driver makes the user EEPROM available for read.
15 *
16 * The registers & config EEPROM should be accessed via i2c-dev.
17 *
18 * The MAX6875 ignores the lowest address bit, so each chip responds to
19 * two addresses - 0x50/0x51 and 0x52/0x53.
20 *
21 * Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
22 * address, so this driver is destructive if loaded for the wrong EEPROM chip.
23 *
24 * This program is free software; you can redistribute it and/or modify
25 * it under the terms of the GNU General Public License as published by
26 * the Free Software Foundation; version 2 of the License.
27 */
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040028
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040029#include <linux/kernel.h>
30#include <linux/init.h>
31#include <linux/module.h>
32#include <linux/slab.h>
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040033#include <linux/i2c.h>
Ingo Molnar5c085d32006-01-18 23:16:04 +010034#include <linux/mutex.h>
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040035
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040036/* The MAX6875 can only read/write 16 bytes at a time */
37#define SLICE_SIZE 16
38#define SLICE_BITS 4
39
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040040/* USER EEPROM is at addresses 0x8100 - 0x82FF */
41#define USER_EEPROM_BASE 0x8100
42#define USER_EEPROM_SIZE 0x0200
43#define USER_EEPROM_SLICES 32
44
45/* MAX6875 commands */
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050046#define MAX6875_CMD_BLK_READ 0x84
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040047
48/* Each client has this additional data */
49struct max6875_data {
Jean Delvarebd8d4212008-07-16 19:30:07 +020050 struct i2c_client *fake_client;
Ingo Molnar5c085d32006-01-18 23:16:04 +010051 struct mutex update_lock;
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050052
53 u32 valid;
54 u8 data[USER_EEPROM_SIZE];
55 unsigned long last_updated[USER_EEPROM_SLICES];
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040056};
57
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050058static void max6875_update_slice(struct i2c_client *client, int slice)
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040059{
60 struct max6875_data *data = i2c_get_clientdata(client);
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050061 int i, j, addr;
62 u8 *buf;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040063
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050064 if (slice >= USER_EEPROM_SLICES)
65 return;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040066
Ingo Molnar5c085d32006-01-18 23:16:04 +010067 mutex_lock(&data->update_lock);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040068
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050069 buf = &data->data[slice << SLICE_BITS];
70
71 if (!(data->valid & (1 << slice)) ||
72 time_after(jiffies, data->last_updated[slice])) {
73
Greg Kroah-Hartmana8decc62005-07-27 12:43:03 -050074 dev_dbg(&client->dev, "Starting update of slice %u\n", slice);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040075
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050076 data->valid &= ~(1 << slice);
77
78 addr = USER_EEPROM_BASE + (slice << SLICE_BITS);
79
80 /* select the eeprom address */
81 if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
82 dev_err(&client->dev, "address set failed\n");
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050083 goto exit_up;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040084 }
85
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050086 if (i2c_check_functionality(client->adapter,
87 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
88 if (i2c_smbus_read_i2c_block_data(client,
89 MAX6875_CMD_BLK_READ,
Jean Delvare4b2643d2007-07-12 14:12:29 +020090 SLICE_SIZE,
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050091 buf) != SLICE_SIZE) {
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050092 goto exit_up;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040093 }
94 } else {
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050095 for (i = 0; i < SLICE_SIZE; i++) {
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040096 j = i2c_smbus_read_byte(client);
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050097 if (j < 0) {
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -050098 goto exit_up;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -040099 }
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500100 buf[i] = j;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400101 }
102 }
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500103 data->last_updated[slice] = jiffies;
104 data->valid |= (1 << slice);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400105 }
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500106exit_up:
Ingo Molnar5c085d32006-01-18 23:16:04 +0100107 mutex_unlock(&data->update_lock);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400108}
109
Chris Wright2c3c8be2010-05-12 18:28:57 -0700110static ssize_t max6875_read(struct file *filp, struct kobject *kobj,
Zhang Rui91a69022007-06-09 13:57:22 +0800111 struct bin_attribute *bin_attr,
112 char *buf, loff_t off, size_t count)
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500113{
114 struct i2c_client *client = kobj_to_i2c_client(kobj);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400115 struct max6875_data *data = i2c_get_clientdata(client);
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500116 int slice, max_slice;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400117
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500118 if (off > USER_EEPROM_SIZE)
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400119 return 0;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400120
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500121 if (off + count > USER_EEPROM_SIZE)
122 count = USER_EEPROM_SIZE - off;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400123
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500124 /* refresh slices which contain requested bytes */
125 max_slice = (off + count - 1) >> SLICE_BITS;
126 for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
127 max6875_update_slice(client, slice);
128
129 memcpy(buf, &data->data[off], count);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400130
131 return count;
132}
133
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400134static struct bin_attribute user_eeprom_attr = {
135 .attr = {
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500136 .name = "eeprom",
137 .mode = S_IRUGO,
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400138 },
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500139 .size = USER_EEPROM_SIZE,
140 .read = max6875_read,
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400141};
142
Jean Delvareb835d7f2009-10-04 22:53:41 +0200143static int max6875_probe(struct i2c_client *client,
144 const struct i2c_device_id *id)
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400145{
Jean Delvarebd8d4212008-07-16 19:30:07 +0200146 struct i2c_adapter *adapter = client->adapter;
Jean Delvareb835d7f2009-10-04 22:53:41 +0200147 struct max6875_data *data;
148 int err;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400149
bgardner@wabtec.com17f990c2005-07-27 12:43:14 -0500150 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500151 | I2C_FUNC_SMBUS_READ_BYTE))
Jean Delvarebd8d4212008-07-16 19:30:07 +0200152 return -ENODEV;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400153
Jean Delvareb835d7f2009-10-04 22:53:41 +0200154 /* Only bind to even addresses */
Jean Delvarebd8d4212008-07-16 19:30:07 +0200155 if (client->addr & 1)
156 return -ENODEV;
157
Deepak Saxena5263ebb2005-10-17 23:09:43 +0200158 if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500159 return -ENOMEM;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400160
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500161 /* A fake client is created on the odd address */
Jean Delvarebd8d4212008-07-16 19:30:07 +0200162 data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1);
163 if (!data->fake_client) {
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500164 err = -ENOMEM;
Jean Delvarebd8d4212008-07-16 19:30:07 +0200165 goto exit_kfree;
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500166 }
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400167
bgardner@wabtec.combc769ff2005-07-12 13:21:11 -0500168 /* Init real i2c_client */
Jean Delvarebd8d4212008-07-16 19:30:07 +0200169 i2c_set_clientdata(client, data);
Ingo Molnar5c085d32006-01-18 23:16:04 +0100170 mutex_init(&data->update_lock);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400171
Jean Delvarebd8d4212008-07-16 19:30:07 +0200172 err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr);
Jean Delvare7d9db672006-09-03 22:20:24 +0200173 if (err)
Jean Delvarebd8d4212008-07-16 19:30:07 +0200174 goto exit_remove_fake;
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400175
176 return 0;
177
Jean Delvarebd8d4212008-07-16 19:30:07 +0200178exit_remove_fake:
179 i2c_unregister_device(data->fake_client);
180exit_kfree:
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400181 kfree(data);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400182 return err;
183}
184
Jean Delvarebd8d4212008-07-16 19:30:07 +0200185static int max6875_remove(struct i2c_client *client)
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400186{
Jean Delvare7d9db672006-09-03 22:20:24 +0200187 struct max6875_data *data = i2c_get_clientdata(client);
188
Jean Delvarebd8d4212008-07-16 19:30:07 +0200189 i2c_unregister_device(data->fake_client);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400190
Jean Delvarebd8d4212008-07-16 19:30:07 +0200191 sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
192 kfree(data);
Jean Delvare7d9db672006-09-03 22:20:24 +0200193
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400194 return 0;
195}
196
Jean Delvarebd8d4212008-07-16 19:30:07 +0200197static const struct i2c_device_id max6875_id[] = {
198 { "max6875", 0 },
199 { }
200};
201
202static struct i2c_driver max6875_driver = {
203 .driver = {
204 .name = "max6875",
205 },
206 .probe = max6875_probe,
207 .remove = max6875_remove,
208 .id_table = max6875_id,
Jean Delvarebd8d4212008-07-16 19:30:07 +0200209};
210
Axel Lina64fe2e2012-01-22 15:36:45 +0800211module_i2c_driver(max6875_driver);
BGardner@Wabtec.comc3bc4ca2005-06-03 13:03:27 -0400212
213MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
214MODULE_DESCRIPTION("MAX6875 driver");
215MODULE_LICENSE("GPL");