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
|
/*
* I2C slave mode EEPROM simulator
*
* Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
* Copyright (C) 2014 by Renesas Electronics Corporation
*
* 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.
*
* Because most IP blocks can only detect one I2C slave address anyhow, this
* driver does not support simulating EEPROM types which take more than one
* address. It is prepared to simulate bigger EEPROMs with an internal 16 bit
* pointer, yet implementation is deferred until the need actually arises.
*/
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
struct eeprom_data {
struct bin_attribute bin;
bool first_write;
spinlock_t buffer_lock;
u8 buffer_idx;
u8 buffer[];
};
static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
struct eeprom_data *eeprom = i2c_get_clientdata(client);
switch (event) {
case I2C_SLAVE_REQ_WRITE_END:
if (eeprom->first_write) {
eeprom->buffer_idx = *val;
eeprom->first_write = false;
} else {
spin_lock(&eeprom->buffer_lock);
eeprom->buffer[eeprom->buffer_idx++] = *val;
spin_unlock(&eeprom->buffer_lock);
}
break;
case I2C_SLAVE_REQ_READ_START:
spin_lock(&eeprom->buffer_lock);
*val = eeprom->buffer[eeprom->buffer_idx];
spin_unlock(&eeprom->buffer_lock);
break;
case I2C_SLAVE_REQ_READ_END:
eeprom->buffer_idx++;
break;
case I2C_SLAVE_STOP:
eeprom->first_write = true;
break;
default:
break;
}
return 0;
}
static ssize_t i2c_slave_eeprom_bin_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, char *buf, loff_t off, size_t count)
{
struct eeprom_data *eeprom;
unsigned long flags;
if (off + count >= attr->size)
return -EFBIG;
eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj));
spin_lock_irqsave(&eeprom->buffer_lock, flags);
memcpy(buf, &eeprom->buffer[off], count);
spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
return count;
}
static ssize_t i2c_slave_eeprom_bin_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, char *buf, loff_t off, size_t count)
{
struct eeprom_data *eeprom;
unsigned long flags;
if (off + count >= attr->size)
return -EFBIG;
eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj));
spin_lock_irqsave(&eeprom->buffer_lock, flags);
memcpy(&eeprom->buffer[off], buf, count);
spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
return count;
}
static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct eeprom_data *eeprom;
int ret;
unsigned size = id->driver_data;
eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
if (!eeprom)
return -ENOMEM;
eeprom->first_write = true;
spin_lock_init(&eeprom->buffer_lock);
i2c_set_clientdata(client, eeprom);
sysfs_bin_attr_init(&eeprom->bin);
eeprom->bin.attr.name = "slave-eeprom";
eeprom->bin.attr.mode = S_IRUSR | S_IWUSR;
eeprom->bin.read = i2c_slave_eeprom_bin_read;
eeprom->bin.write = i2c_slave_eeprom_bin_write;
eeprom->bin.size = size;
ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin);
if (ret)
return ret;
ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb);
if (ret) {
sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
return ret;
}
return 0;
};
static int i2c_slave_eeprom_remove(struct i2c_client *client)
{
struct eeprom_data *eeprom = i2c_get_clientdata(client);
i2c_slave_unregister(client);
sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
return 0;
}
static const struct i2c_device_id i2c_slave_eeprom_id[] = {
{ "slave-24c02", 2048 / 8 },
{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
static struct i2c_driver i2c_slave_eeprom_driver = {
.driver = {
.name = "i2c-slave-eeprom",
.owner = THIS_MODULE,
},
.probe = i2c_slave_eeprom_probe,
.remove = i2c_slave_eeprom_remove,
.id_table = i2c_slave_eeprom_id,
};
module_i2c_driver(i2c_slave_eeprom_driver);
MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
MODULE_DESCRIPTION("I2C slave mode EEPROM simulator");
MODULE_LICENSE("GPL v2");
|
