1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
|
/*
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 client;
struct mutex 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 = {
.driver = {
.name = "max6875",
},
.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;
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,
};
static int max6875_attach_adapter(struct i2c_adapter *adapter)
{
return i2c_probe(adapter, &addr_data, max6875_detect);
}
/* This function is called by i2c_probe */
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;
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 = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
return -ENOMEM;
/* A fake client is created on the odd address */
if (!(fake_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
err = -ENOMEM;
goto exit_kfree1;
}
/* 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);
mutex_init(&data->update_lock);
/* Init fake client data */
i2c_set_clientdata(fake_client, NULL);
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);
if ((err = i2c_attach_client(real_client)) != 0)
goto exit_kfree2;
if ((err = i2c_attach_client(fake_client)) != 0)
goto exit_detach1;
err = sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr);
if (err)
goto exit_detach2;
return 0;
exit_detach2:
i2c_detach_client(fake_client);
exit_detach1:
i2c_detach_client(real_client);
exit_kfree2:
kfree(fake_client);
exit_kfree1:
kfree(data);
return err;
}
/* Will be called for both the real client and the fake client */
static int max6875_detach_client(struct i2c_client *client)
{
int err;
struct max6875_data *data = i2c_get_clientdata(client);
/* data is NULL for the fake client */
if (data)
sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
err = i2c_detach_client(client);
if (err)
return err;
if (data) /* real client */
kfree(data);
else /* fake client */
kfree(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);
|
