Commit | Line | Data |
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c3bc4cae BW |
1 | /* |
2 | max6875.c - driver for MAX6874/MAX6875 | |
3 | ||
4 | Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com> | |
5 | ||
6 | Based on i2c/chips/eeprom.c | |
7 | ||
bc769ff8 | 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 | |
c3bc4cae | 13 | |
bc769ff8 | 14 | This driver makes the user EEPROM available for read. |
c3bc4cae | 15 | |
bc769ff8 | 16 | The registers & config EEPROM should be accessed via i2c-dev. |
c3bc4cae | 17 | |
bc769ff8 | 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. | |
c3bc4cae BW |
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 | */ | |
28 | ||
c3bc4cae BW |
29 | #include <linux/kernel.h> |
30 | #include <linux/init.h> | |
31 | #include <linux/module.h> | |
32 | #include <linux/slab.h> | |
c3bc4cae | 33 | #include <linux/i2c.h> |
5c085d36 | 34 | #include <linux/mutex.h> |
c3bc4cae | 35 | |
bc769ff8 | 36 | /* Do not scan - the MAX6875 access method will write to some EEPROM chips */ |
2cdddeb8 | 37 | static const unsigned short normal_i2c[] = { I2C_CLIENT_END }; |
c3bc4cae BW |
38 | |
39 | /* Insmod parameters */ | |
f4b50261 | 40 | I2C_CLIENT_INSMOD_1(max6875); |
c3bc4cae | 41 | |
c3bc4cae BW |
42 | /* The MAX6875 can only read/write 16 bytes at a time */ |
43 | #define SLICE_SIZE 16 | |
44 | #define SLICE_BITS 4 | |
45 | ||
c3bc4cae BW |
46 | /* USER EEPROM is at addresses 0x8100 - 0x82FF */ |
47 | #define USER_EEPROM_BASE 0x8100 | |
48 | #define USER_EEPROM_SIZE 0x0200 | |
49 | #define USER_EEPROM_SLICES 32 | |
50 | ||
51 | /* MAX6875 commands */ | |
bc769ff8 | 52 | #define MAX6875_CMD_BLK_READ 0x84 |
c3bc4cae BW |
53 | |
54 | /* Each client has this additional data */ | |
55 | struct max6875_data { | |
bd8d421f | 56 | struct i2c_client *fake_client; |
5c085d36 | 57 | struct mutex update_lock; |
bc769ff8 | 58 | |
59 | u32 valid; | |
60 | u8 data[USER_EEPROM_SIZE]; | |
61 | unsigned long last_updated[USER_EEPROM_SLICES]; | |
c3bc4cae BW |
62 | }; |
63 | ||
bc769ff8 | 64 | static void max6875_update_slice(struct i2c_client *client, int slice) |
c3bc4cae BW |
65 | { |
66 | struct max6875_data *data = i2c_get_clientdata(client); | |
bc769ff8 | 67 | int i, j, addr; |
68 | u8 *buf; | |
c3bc4cae | 69 | |
bc769ff8 | 70 | if (slice >= USER_EEPROM_SLICES) |
71 | return; | |
c3bc4cae | 72 | |
5c085d36 | 73 | mutex_lock(&data->update_lock); |
c3bc4cae | 74 | |
bc769ff8 | 75 | buf = &data->data[slice << SLICE_BITS]; |
76 | ||
77 | if (!(data->valid & (1 << slice)) || | |
78 | time_after(jiffies, data->last_updated[slice])) { | |
79 | ||
a8decc65 | 80 | dev_dbg(&client->dev, "Starting update of slice %u\n", slice); |
c3bc4cae | 81 | |
bc769ff8 | 82 | data->valid &= ~(1 << slice); |
c3bc4cae | 83 | |
bc769ff8 | 84 | addr = USER_EEPROM_BASE + (slice << SLICE_BITS); |
85 | ||
86 | /* select the eeprom address */ | |
87 | if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) { | |
88 | dev_err(&client->dev, "address set failed\n"); | |
bc769ff8 | 89 | goto exit_up; |
c3bc4cae BW |
90 | } |
91 | ||
bc769ff8 | 92 | if (i2c_check_functionality(client->adapter, |
93 | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { | |
94 | if (i2c_smbus_read_i2c_block_data(client, | |
95 | MAX6875_CMD_BLK_READ, | |
4b2643d7 | 96 | SLICE_SIZE, |
bc769ff8 | 97 | buf) != SLICE_SIZE) { |
bc769ff8 | 98 | goto exit_up; |
c3bc4cae | 99 | } |
c3bc4cae | 100 | } else { |
bc769ff8 | 101 | for (i = 0; i < SLICE_SIZE; i++) { |
c3bc4cae | 102 | j = i2c_smbus_read_byte(client); |
bc769ff8 | 103 | if (j < 0) { |
bc769ff8 | 104 | goto exit_up; |
c3bc4cae | 105 | } |
bc769ff8 | 106 | buf[i] = j; |
c3bc4cae BW |
107 | } |
108 | } | |
bc769ff8 | 109 | data->last_updated[slice] = jiffies; |
110 | data->valid |= (1 << slice); | |
c3bc4cae | 111 | } |
bc769ff8 | 112 | exit_up: |
5c085d36 | 113 | mutex_unlock(&data->update_lock); |
c3bc4cae BW |
114 | } |
115 | ||
91a69029 ZR |
116 | static ssize_t max6875_read(struct kobject *kobj, |
117 | struct bin_attribute *bin_attr, | |
118 | char *buf, loff_t off, size_t count) | |
c3bc4cae | 119 | { |
bc769ff8 | 120 | struct i2c_client *client = kobj_to_i2c_client(kobj); |
c3bc4cae | 121 | struct max6875_data *data = i2c_get_clientdata(client); |
bc769ff8 | 122 | int slice, max_slice; |
c3bc4cae | 123 | |
bc769ff8 | 124 | if (off > USER_EEPROM_SIZE) |
c3bc4cae | 125 | return 0; |
c3bc4cae | 126 | |
bc769ff8 | 127 | if (off + count > USER_EEPROM_SIZE) |
128 | count = USER_EEPROM_SIZE - off; | |
c3bc4cae | 129 | |
bc769ff8 | 130 | /* refresh slices which contain requested bytes */ |
131 | max_slice = (off + count - 1) >> SLICE_BITS; | |
132 | for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++) | |
133 | max6875_update_slice(client, slice); | |
c3bc4cae | 134 | |
bc769ff8 | 135 | memcpy(buf, &data->data[off], count); |
c3bc4cae | 136 | |
bc769ff8 | 137 | return count; |
c3bc4cae BW |
138 | } |
139 | ||
140 | static struct bin_attribute user_eeprom_attr = { | |
141 | .attr = { | |
bc769ff8 | 142 | .name = "eeprom", |
143 | .mode = S_IRUGO, | |
c3bc4cae | 144 | }, |
bc769ff8 | 145 | .size = USER_EEPROM_SIZE, |
146 | .read = max6875_read, | |
c3bc4cae BW |
147 | }; |
148 | ||
bd8d421f JD |
149 | /* Return 0 if detection is successful, -ENODEV otherwise */ |
150 | static int max6875_detect(struct i2c_client *client, int kind, | |
151 | struct i2c_board_info *info) | |
c3bc4cae | 152 | { |
bd8d421f | 153 | struct i2c_adapter *adapter = client->adapter; |
c3bc4cae | 154 | |
17f990c8 | 155 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
bc769ff8 | 156 | | I2C_FUNC_SMBUS_READ_BYTE)) |
bd8d421f | 157 | return -ENODEV; |
bc769ff8 | 158 | |
159 | /* Only check even addresses */ | |
bd8d421f JD |
160 | if (client->addr & 1) |
161 | return -ENODEV; | |
162 | ||
163 | strlcpy(info->type, "max6875", I2C_NAME_SIZE); | |
164 | ||
165 | return 0; | |
166 | } | |
167 | ||
168 | static int max6875_probe(struct i2c_client *client, | |
169 | const struct i2c_device_id *id) | |
170 | { | |
171 | struct max6875_data *data; | |
172 | int err; | |
bc769ff8 | 173 | |
5263ebb5 | 174 | if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL))) |
bc769ff8 | 175 | return -ENOMEM; |
c3bc4cae | 176 | |
bc769ff8 | 177 | /* A fake client is created on the odd address */ |
bd8d421f JD |
178 | data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1); |
179 | if (!data->fake_client) { | |
bc769ff8 | 180 | err = -ENOMEM; |
bd8d421f | 181 | goto exit_kfree; |
bc769ff8 | 182 | } |
bc769ff8 | 183 | |
184 | /* Init real i2c_client */ | |
bd8d421f | 185 | i2c_set_clientdata(client, data); |
5c085d36 | 186 | mutex_init(&data->update_lock); |
c3bc4cae | 187 | |
bd8d421f | 188 | err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr); |
7d9db67f | 189 | if (err) |
bd8d421f | 190 | goto exit_remove_fake; |
c3bc4cae BW |
191 | |
192 | return 0; | |
193 | ||
bd8d421f JD |
194 | exit_remove_fake: |
195 | i2c_unregister_device(data->fake_client); | |
196 | exit_kfree: | |
c3bc4cae | 197 | kfree(data); |
c3bc4cae BW |
198 | return err; |
199 | } | |
200 | ||
bd8d421f | 201 | static int max6875_remove(struct i2c_client *client) |
c3bc4cae | 202 | { |
7d9db67f JD |
203 | struct max6875_data *data = i2c_get_clientdata(client); |
204 | ||
bd8d421f | 205 | i2c_unregister_device(data->fake_client); |
c3bc4cae | 206 | |
bd8d421f JD |
207 | sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr); |
208 | kfree(data); | |
7d9db67f | 209 | |
c3bc4cae BW |
210 | return 0; |
211 | } | |
212 | ||
bd8d421f JD |
213 | static const struct i2c_device_id max6875_id[] = { |
214 | { "max6875", 0 }, | |
215 | { } | |
216 | }; | |
217 | ||
218 | static struct i2c_driver max6875_driver = { | |
219 | .driver = { | |
220 | .name = "max6875", | |
221 | }, | |
222 | .probe = max6875_probe, | |
223 | .remove = max6875_remove, | |
224 | .id_table = max6875_id, | |
225 | ||
226 | .detect = max6875_detect, | |
227 | .address_data = &addr_data, | |
228 | }; | |
229 | ||
c3bc4cae BW |
230 | static int __init max6875_init(void) |
231 | { | |
232 | return i2c_add_driver(&max6875_driver); | |
233 | } | |
234 | ||
235 | static void __exit max6875_exit(void) | |
236 | { | |
237 | i2c_del_driver(&max6875_driver); | |
238 | } | |
239 | ||
240 | ||
241 | MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); | |
242 | MODULE_DESCRIPTION("MAX6875 driver"); | |
243 | MODULE_LICENSE("GPL"); | |
244 | ||
245 | module_init(max6875_init); | |
246 | module_exit(max6875_exit); |