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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* I2C slave mode EEPROM simulator
*
* Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
* Copyright (C) 2014 by Renesas Electronics Corporation
*
* Because most slave IP cores can only detect one I2C slave address anyhow,
* this driver does not support simulating EEPROM types which take more than
* one address.
*/
/*
* FIXME: What to do if only 8 bits of a 16 bit address are sent?
* The ST-M24C64 sends only 0xff then. Needs verification with other
* EEPROMs, though. We currently use the 8 bit as a valid address.
*/
#include <linux/bitfield.h>
#include <linux/firmware.h>
#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;
spinlock_t buffer_lock;
u16 buffer_idx;
u16 address_mask;
u8 num_address_bytes;
u8 idx_write_cnt;
bool read_only;
u8 buffer[];
};
#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
#define I2C_SLAVE_FLAG_RO BIT(17)
#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))
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_WRITE_RECEIVED:
if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
if (eeprom->idx_write_cnt == 0)
eeprom->buffer_idx = 0;
eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
eeprom->idx_write_cnt++;
} else {
if (!eeprom->read_only) {
spin_lock(&eeprom->buffer_lock);
eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
spin_unlock(&eeprom->buffer_lock);
}
}
break;
case I2C_SLAVE_READ_PROCESSED:
/* The previous byte made it to the bus, get next one */
eeprom->buffer_idx++;
fallthrough;
case I2C_SLAVE_READ_REQUESTED:
spin_lock(&eeprom->buffer_lock);
*val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
spin_unlock(&eeprom->buffer_lock);
/*
* Do not increment buffer_idx here, because we don't know if
* this byte will be actually used. Read Linux I2C slave docs
* for details.
*/
break;
case I2C_SLAVE_STOP:
case I2C_SLAVE_WRITE_REQUESTED:
eeprom->idx_write_cnt = 0;
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;
eeprom = dev_get_drvdata(kobj_to_dev(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;
eeprom = dev_get_drvdata(kobj_to_dev(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_init_eeprom_data(struct eeprom_data *eeprom, struct i2c_client *client,
unsigned int size)
{
const struct firmware *fw;
const char *eeprom_data;
int ret = device_property_read_string(&client->dev, "firmware-name", &eeprom_data);
if (!ret) {
ret = request_firmware_into_buf(&fw, eeprom_data, &client->dev,
eeprom->buffer, size);
if (ret)
return ret;
release_firmware(fw);
} else {
/* An empty eeprom typically has all bits set to 1 */
memset(eeprom->buffer, 0xff, size);
}
return 0;
}
static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct eeprom_data *eeprom;
int ret;
unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
if (!eeprom)
return -ENOMEM;
eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
eeprom->address_mask = size - 1;
eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
spin_lock_init(&eeprom->buffer_lock);
i2c_set_clientdata(client, eeprom);
ret = i2c_slave_init_eeprom_data(eeprom, client, size);
if (ret)
return ret;
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 void 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);
}
static const struct i2c_device_id i2c_slave_eeprom_id[] = {
{ "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, 0) },
{ "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, I2C_SLAVE_FLAG_RO) },
{ "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
{ "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
{ "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
static struct i2c_driver i2c_slave_eeprom_driver = {
.driver = {
.name = "i2c-slave-eeprom",
},
.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");
|
