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 | ||
4b364f23 | 6 | Based on eeprom.c |
c3bc4cae | 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 | |
c3bc4cae BW |
36 | /* The MAX6875 can only read/write 16 bytes at a time */ |
37 | #define SLICE_SIZE 16 | |
38 | #define SLICE_BITS 4 | |
39 | ||
c3bc4cae BW |
40 | /* 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 */ | |
bc769ff8 | 46 | #define MAX6875_CMD_BLK_READ 0x84 |
c3bc4cae BW |
47 | |
48 | /* Each client has this additional data */ | |
49 | struct max6875_data { | |
bd8d421f | 50 | struct i2c_client *fake_client; |
5c085d36 | 51 | struct mutex update_lock; |
bc769ff8 | 52 | |
53 | u32 valid; | |
54 | u8 data[USER_EEPROM_SIZE]; | |
55 | unsigned long last_updated[USER_EEPROM_SLICES]; | |
c3bc4cae BW |
56 | }; |
57 | ||
bc769ff8 | 58 | static void max6875_update_slice(struct i2c_client *client, int slice) |
c3bc4cae BW |
59 | { |
60 | struct max6875_data *data = i2c_get_clientdata(client); | |
bc769ff8 | 61 | int i, j, addr; |
62 | u8 *buf; | |
c3bc4cae | 63 | |
bc769ff8 | 64 | if (slice >= USER_EEPROM_SLICES) |
65 | return; | |
c3bc4cae | 66 | |
5c085d36 | 67 | mutex_lock(&data->update_lock); |
c3bc4cae | 68 | |
bc769ff8 | 69 | buf = &data->data[slice << SLICE_BITS]; |
70 | ||
71 | if (!(data->valid & (1 << slice)) || | |
72 | time_after(jiffies, data->last_updated[slice])) { | |
73 | ||
a8decc65 | 74 | dev_dbg(&client->dev, "Starting update of slice %u\n", slice); |
c3bc4cae | 75 | |
bc769ff8 | 76 | data->valid &= ~(1 << slice); |
c3bc4cae | 77 | |
bc769ff8 | 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"); | |
bc769ff8 | 83 | goto exit_up; |
c3bc4cae BW |
84 | } |
85 | ||
bc769ff8 | 86 | 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, | |
4b2643d7 | 90 | SLICE_SIZE, |
bc769ff8 | 91 | buf) != SLICE_SIZE) { |
bc769ff8 | 92 | goto exit_up; |
c3bc4cae | 93 | } |
c3bc4cae | 94 | } else { |
bc769ff8 | 95 | for (i = 0; i < SLICE_SIZE; i++) { |
c3bc4cae | 96 | j = i2c_smbus_read_byte(client); |
bc769ff8 | 97 | if (j < 0) { |
bc769ff8 | 98 | goto exit_up; |
c3bc4cae | 99 | } |
bc769ff8 | 100 | buf[i] = j; |
c3bc4cae BW |
101 | } |
102 | } | |
bc769ff8 | 103 | data->last_updated[slice] = jiffies; |
104 | data->valid |= (1 << slice); | |
c3bc4cae | 105 | } |
bc769ff8 | 106 | exit_up: |
5c085d36 | 107 | mutex_unlock(&data->update_lock); |
c3bc4cae BW |
108 | } |
109 | ||
91a69029 ZR |
110 | static ssize_t max6875_read(struct kobject *kobj, |
111 | struct bin_attribute *bin_attr, | |
112 | char *buf, loff_t off, size_t count) | |
c3bc4cae | 113 | { |
bc769ff8 | 114 | struct i2c_client *client = kobj_to_i2c_client(kobj); |
c3bc4cae | 115 | struct max6875_data *data = i2c_get_clientdata(client); |
bc769ff8 | 116 | int slice, max_slice; |
c3bc4cae | 117 | |
bc769ff8 | 118 | if (off > USER_EEPROM_SIZE) |
c3bc4cae | 119 | return 0; |
c3bc4cae | 120 | |
bc769ff8 | 121 | if (off + count > USER_EEPROM_SIZE) |
122 | count = USER_EEPROM_SIZE - off; | |
c3bc4cae | 123 | |
bc769ff8 | 124 | /* 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); | |
c3bc4cae | 128 | |
bc769ff8 | 129 | memcpy(buf, &data->data[off], count); |
c3bc4cae | 130 | |
bc769ff8 | 131 | return count; |
c3bc4cae BW |
132 | } |
133 | ||
134 | static struct bin_attribute user_eeprom_attr = { | |
135 | .attr = { | |
bc769ff8 | 136 | .name = "eeprom", |
137 | .mode = S_IRUGO, | |
c3bc4cae | 138 | }, |
bc769ff8 | 139 | .size = USER_EEPROM_SIZE, |
140 | .read = max6875_read, | |
c3bc4cae BW |
141 | }; |
142 | ||
b835d7fb JD |
143 | static int max6875_probe(struct i2c_client *client, |
144 | const struct i2c_device_id *id) | |
c3bc4cae | 145 | { |
bd8d421f | 146 | struct i2c_adapter *adapter = client->adapter; |
b835d7fb JD |
147 | struct max6875_data *data; |
148 | int err; | |
c3bc4cae | 149 | |
17f990c8 | 150 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
bc769ff8 | 151 | | I2C_FUNC_SMBUS_READ_BYTE)) |
bd8d421f | 152 | return -ENODEV; |
bc769ff8 | 153 | |
b835d7fb | 154 | /* Only bind to even addresses */ |
bd8d421f JD |
155 | if (client->addr & 1) |
156 | return -ENODEV; | |
157 | ||
5263ebb5 | 158 | if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL))) |
bc769ff8 | 159 | return -ENOMEM; |
c3bc4cae | 160 | |
bc769ff8 | 161 | /* A fake client is created on the odd address */ |
bd8d421f JD |
162 | data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1); |
163 | if (!data->fake_client) { | |
bc769ff8 | 164 | err = -ENOMEM; |
bd8d421f | 165 | goto exit_kfree; |
bc769ff8 | 166 | } |
bc769ff8 | 167 | |
168 | /* Init real i2c_client */ | |
bd8d421f | 169 | i2c_set_clientdata(client, data); |
5c085d36 | 170 | mutex_init(&data->update_lock); |
c3bc4cae | 171 | |
bd8d421f | 172 | err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr); |
7d9db67f | 173 | if (err) |
bd8d421f | 174 | goto exit_remove_fake; |
c3bc4cae BW |
175 | |
176 | return 0; | |
177 | ||
bd8d421f JD |
178 | exit_remove_fake: |
179 | i2c_unregister_device(data->fake_client); | |
180 | exit_kfree: | |
c3bc4cae | 181 | kfree(data); |
c3bc4cae BW |
182 | return err; |
183 | } | |
184 | ||
bd8d421f | 185 | static int max6875_remove(struct i2c_client *client) |
c3bc4cae | 186 | { |
7d9db67f JD |
187 | struct max6875_data *data = i2c_get_clientdata(client); |
188 | ||
bd8d421f | 189 | i2c_unregister_device(data->fake_client); |
c3bc4cae | 190 | |
bd8d421f JD |
191 | sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr); |
192 | kfree(data); | |
7d9db67f | 193 | |
c3bc4cae BW |
194 | return 0; |
195 | } | |
196 | ||
bd8d421f JD |
197 | static const struct i2c_device_id max6875_id[] = { |
198 | { "max6875", 0 }, | |
199 | { } | |
200 | }; | |
201 | ||
202 | static struct i2c_driver max6875_driver = { | |
203 | .driver = { | |
204 | .name = "max6875", | |
205 | }, | |
206 | .probe = max6875_probe, | |
207 | .remove = max6875_remove, | |
208 | .id_table = max6875_id, | |
bd8d421f JD |
209 | }; |
210 | ||
c3bc4cae BW |
211 | static int __init max6875_init(void) |
212 | { | |
213 | return i2c_add_driver(&max6875_driver); | |
214 | } | |
215 | ||
216 | static void __exit max6875_exit(void) | |
217 | { | |
218 | i2c_del_driver(&max6875_driver); | |
219 | } | |
220 | ||
221 | ||
222 | MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); | |
223 | MODULE_DESCRIPTION("MAX6875 driver"); | |
224 | MODULE_LICENSE("GPL"); | |
225 | ||
226 | module_init(max6875_init); | |
227 | module_exit(max6875_exit); |