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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> |
bc769ff8 | 34 | #include <asm/semaphore.h> |
c3bc4cae | 35 | |
bc769ff8 | 36 | /* Do not scan - the MAX6875 access method will write to some EEPROM chips */ |
9ab1ee2a | 37 | static 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 { | |
56 | struct i2c_client client; | |
57 | struct semaphore 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 | ||
64 | static int max6875_attach_adapter(struct i2c_adapter *adapter); | |
65 | static int max6875_detect(struct i2c_adapter *adapter, int address, int kind); | |
66 | static int max6875_detach_client(struct i2c_client *client); | |
67 | ||
68 | /* This is the driver that will be inserted */ | |
69 | static struct i2c_driver max6875_driver = { | |
a9718b0c | 70 | .driver = { |
a9718b0c LR |
71 | .name = "max6875", |
72 | }, | |
c3bc4cae BW |
73 | .attach_adapter = max6875_attach_adapter, |
74 | .detach_client = max6875_detach_client, | |
75 | }; | |
76 | ||
bc769ff8 | 77 | static void max6875_update_slice(struct i2c_client *client, int slice) |
c3bc4cae BW |
78 | { |
79 | struct max6875_data *data = i2c_get_clientdata(client); | |
bc769ff8 | 80 | int i, j, addr; |
81 | u8 *buf; | |
c3bc4cae | 82 | |
bc769ff8 | 83 | if (slice >= USER_EEPROM_SLICES) |
84 | return; | |
c3bc4cae BW |
85 | |
86 | down(&data->update_lock); | |
87 | ||
bc769ff8 | 88 | buf = &data->data[slice << SLICE_BITS]; |
89 | ||
90 | if (!(data->valid & (1 << slice)) || | |
91 | time_after(jiffies, data->last_updated[slice])) { | |
92 | ||
a8decc65 | 93 | dev_dbg(&client->dev, "Starting update of slice %u\n", slice); |
c3bc4cae | 94 | |
bc769ff8 | 95 | data->valid &= ~(1 << slice); |
c3bc4cae | 96 | |
bc769ff8 | 97 | addr = USER_EEPROM_BASE + (slice << SLICE_BITS); |
98 | ||
99 | /* select the eeprom address */ | |
100 | if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) { | |
101 | dev_err(&client->dev, "address set failed\n"); | |
bc769ff8 | 102 | goto exit_up; |
c3bc4cae BW |
103 | } |
104 | ||
bc769ff8 | 105 | if (i2c_check_functionality(client->adapter, |
106 | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { | |
107 | if (i2c_smbus_read_i2c_block_data(client, | |
108 | MAX6875_CMD_BLK_READ, | |
109 | buf) != SLICE_SIZE) { | |
bc769ff8 | 110 | goto exit_up; |
c3bc4cae | 111 | } |
c3bc4cae | 112 | } else { |
bc769ff8 | 113 | for (i = 0; i < SLICE_SIZE; i++) { |
c3bc4cae | 114 | j = i2c_smbus_read_byte(client); |
bc769ff8 | 115 | if (j < 0) { |
bc769ff8 | 116 | goto exit_up; |
c3bc4cae | 117 | } |
bc769ff8 | 118 | buf[i] = j; |
c3bc4cae BW |
119 | } |
120 | } | |
bc769ff8 | 121 | data->last_updated[slice] = jiffies; |
122 | data->valid |= (1 << slice); | |
c3bc4cae | 123 | } |
bc769ff8 | 124 | exit_up: |
c3bc4cae | 125 | up(&data->update_lock); |
c3bc4cae BW |
126 | } |
127 | ||
bc769ff8 | 128 | static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off, |
129 | size_t count) | |
c3bc4cae | 130 | { |
bc769ff8 | 131 | struct i2c_client *client = kobj_to_i2c_client(kobj); |
c3bc4cae | 132 | struct max6875_data *data = i2c_get_clientdata(client); |
bc769ff8 | 133 | int slice, max_slice; |
c3bc4cae | 134 | |
bc769ff8 | 135 | if (off > USER_EEPROM_SIZE) |
c3bc4cae | 136 | return 0; |
c3bc4cae | 137 | |
bc769ff8 | 138 | if (off + count > USER_EEPROM_SIZE) |
139 | count = USER_EEPROM_SIZE - off; | |
c3bc4cae | 140 | |
bc769ff8 | 141 | /* refresh slices which contain requested bytes */ |
142 | max_slice = (off + count - 1) >> SLICE_BITS; | |
143 | for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++) | |
144 | max6875_update_slice(client, slice); | |
c3bc4cae | 145 | |
bc769ff8 | 146 | memcpy(buf, &data->data[off], count); |
c3bc4cae | 147 | |
bc769ff8 | 148 | return count; |
c3bc4cae BW |
149 | } |
150 | ||
151 | static struct bin_attribute user_eeprom_attr = { | |
152 | .attr = { | |
bc769ff8 | 153 | .name = "eeprom", |
154 | .mode = S_IRUGO, | |
c3bc4cae BW |
155 | .owner = THIS_MODULE, |
156 | }, | |
bc769ff8 | 157 | .size = USER_EEPROM_SIZE, |
158 | .read = max6875_read, | |
c3bc4cae BW |
159 | }; |
160 | ||
161 | static int max6875_attach_adapter(struct i2c_adapter *adapter) | |
162 | { | |
2ed2dc3c | 163 | return i2c_probe(adapter, &addr_data, max6875_detect); |
c3bc4cae BW |
164 | } |
165 | ||
2ed2dc3c | 166 | /* This function is called by i2c_probe */ |
c3bc4cae BW |
167 | static int max6875_detect(struct i2c_adapter *adapter, int address, int kind) |
168 | { | |
bc769ff8 | 169 | struct i2c_client *real_client; |
170 | struct i2c_client *fake_client; | |
c3bc4cae BW |
171 | struct max6875_data *data; |
172 | int err = 0; | |
173 | ||
17f990c8 | 174 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
bc769ff8 | 175 | | I2C_FUNC_SMBUS_READ_BYTE)) |
176 | return 0; | |
177 | ||
178 | /* Only check even addresses */ | |
179 | if (address & 1) | |
180 | return 0; | |
181 | ||
5263ebb5 | 182 | if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL))) |
bc769ff8 | 183 | return -ENOMEM; |
c3bc4cae | 184 | |
bc769ff8 | 185 | /* A fake client is created on the odd address */ |
5263ebb5 | 186 | if (!(fake_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) { |
bc769ff8 | 187 | err = -ENOMEM; |
188 | goto exit_kfree1; | |
189 | } | |
bc769ff8 | 190 | |
191 | /* Init real i2c_client */ | |
192 | real_client = &data->client; | |
193 | i2c_set_clientdata(real_client, data); | |
194 | real_client->addr = address; | |
195 | real_client->adapter = adapter; | |
196 | real_client->driver = &max6875_driver; | |
197 | real_client->flags = 0; | |
198 | strlcpy(real_client->name, "max6875", I2C_NAME_SIZE); | |
c3bc4cae BW |
199 | init_MUTEX(&data->update_lock); |
200 | ||
bc769ff8 | 201 | /* Init fake client data */ |
202 | /* set the client data to the i2c_client so that it will get freed */ | |
203 | i2c_set_clientdata(fake_client, fake_client); | |
204 | fake_client->addr = address | 1; | |
205 | fake_client->adapter = adapter; | |
206 | fake_client->driver = &max6875_driver; | |
207 | fake_client->flags = 0; | |
17f990c8 | 208 | strlcpy(fake_client->name, "max6875 subclient", I2C_NAME_SIZE); |
bc769ff8 | 209 | |
210 | /* Prevent 24RF08 corruption (in case of user error) */ | |
211 | i2c_smbus_write_quick(real_client, 0); | |
212 | ||
213 | if ((err = i2c_attach_client(real_client)) != 0) | |
214 | goto exit_kfree2; | |
215 | ||
216 | if ((err = i2c_attach_client(fake_client)) != 0) | |
217 | goto exit_detach; | |
218 | ||
219 | sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr); | |
c3bc4cae BW |
220 | |
221 | return 0; | |
222 | ||
bc769ff8 | 223 | exit_detach: |
224 | i2c_detach_client(real_client); | |
225 | exit_kfree2: | |
226 | kfree(fake_client); | |
227 | exit_kfree1: | |
c3bc4cae | 228 | kfree(data); |
c3bc4cae BW |
229 | return err; |
230 | } | |
231 | ||
232 | static int max6875_detach_client(struct i2c_client *client) | |
233 | { | |
234 | int err; | |
235 | ||
236 | err = i2c_detach_client(client); | |
7bef5594 | 237 | if (err) |
c3bc4cae | 238 | return err; |
c3bc4cae | 239 | kfree(i2c_get_clientdata(client)); |
c3bc4cae BW |
240 | return 0; |
241 | } | |
242 | ||
243 | static int __init max6875_init(void) | |
244 | { | |
245 | return i2c_add_driver(&max6875_driver); | |
246 | } | |
247 | ||
248 | static void __exit max6875_exit(void) | |
249 | { | |
250 | i2c_del_driver(&max6875_driver); | |
251 | } | |
252 | ||
253 | ||
254 | MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); | |
255 | MODULE_DESCRIPTION("MAX6875 driver"); | |
256 | MODULE_LICENSE("GPL"); | |
257 | ||
258 | module_init(max6875_init); | |
259 | module_exit(max6875_exit); |