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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 BW |
33 | #include <linux/i2c.h> |
34 | #include <linux/i2c-sensor.h> | |
bc769ff8 | 35 | #include <asm/semaphore.h> |
c3bc4cae | 36 | |
bc769ff8 | 37 | /* Do not scan - the MAX6875 access method will write to some EEPROM chips */ |
9ab1ee2a | 38 | static unsigned short normal_i2c[] = {I2C_CLIENT_END}; |
c3bc4cae BW |
39 | static unsigned int normal_isa[] = {I2C_CLIENT_ISA_END}; |
40 | ||
41 | /* Insmod parameters */ | |
42 | SENSORS_INSMOD_1(max6875); | |
43 | ||
c3bc4cae BW |
44 | /* The MAX6875 can only read/write 16 bytes at a time */ |
45 | #define SLICE_SIZE 16 | |
46 | #define SLICE_BITS 4 | |
47 | ||
c3bc4cae BW |
48 | /* USER EEPROM is at addresses 0x8100 - 0x82FF */ |
49 | #define USER_EEPROM_BASE 0x8100 | |
50 | #define USER_EEPROM_SIZE 0x0200 | |
51 | #define USER_EEPROM_SLICES 32 | |
52 | ||
53 | /* MAX6875 commands */ | |
bc769ff8 | 54 | #define MAX6875_CMD_BLK_READ 0x84 |
c3bc4cae BW |
55 | |
56 | /* Each client has this additional data */ | |
57 | struct max6875_data { | |
58 | struct i2c_client client; | |
59 | struct semaphore update_lock; | |
bc769ff8 | 60 | |
61 | u32 valid; | |
62 | u8 data[USER_EEPROM_SIZE]; | |
63 | unsigned long last_updated[USER_EEPROM_SLICES]; | |
c3bc4cae BW |
64 | }; |
65 | ||
66 | static int max6875_attach_adapter(struct i2c_adapter *adapter); | |
67 | static int max6875_detect(struct i2c_adapter *adapter, int address, int kind); | |
68 | static int max6875_detach_client(struct i2c_client *client); | |
69 | ||
70 | /* This is the driver that will be inserted */ | |
71 | static struct i2c_driver max6875_driver = { | |
72 | .owner = THIS_MODULE, | |
73 | .name = "max6875", | |
74 | .flags = I2C_DF_NOTIFY, | |
75 | .attach_adapter = max6875_attach_adapter, | |
76 | .detach_client = max6875_detach_client, | |
77 | }; | |
78 | ||
bc769ff8 | 79 | static void max6875_update_slice(struct i2c_client *client, int slice) |
c3bc4cae BW |
80 | { |
81 | struct max6875_data *data = i2c_get_clientdata(client); | |
bc769ff8 | 82 | int i, j, addr; |
83 | u8 *buf; | |
c3bc4cae BW |
84 | int retval = 0; |
85 | ||
bc769ff8 | 86 | if (slice >= USER_EEPROM_SLICES) |
87 | return; | |
c3bc4cae BW |
88 | |
89 | down(&data->update_lock); | |
90 | ||
bc769ff8 | 91 | buf = &data->data[slice << SLICE_BITS]; |
92 | ||
93 | if (!(data->valid & (1 << slice)) || | |
94 | time_after(jiffies, data->last_updated[slice])) { | |
95 | ||
96 | dev_dbg(&client->dev, "Starting update of slice %u\n", | |
c3bc4cae BW |
97 | slice, blk->base); |
98 | ||
bc769ff8 | 99 | data->valid &= ~(1 << slice); |
c3bc4cae | 100 | |
bc769ff8 | 101 | addr = USER_EEPROM_BASE + (slice << SLICE_BITS); |
102 | ||
103 | /* select the eeprom address */ | |
104 | if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) { | |
105 | dev_err(&client->dev, "address set failed\n"); | |
106 | retval = -1; | |
107 | goto exit_up; | |
c3bc4cae BW |
108 | } |
109 | ||
bc769ff8 | 110 | if (i2c_check_functionality(client->adapter, |
111 | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { | |
112 | if (i2c_smbus_read_i2c_block_data(client, | |
113 | MAX6875_CMD_BLK_READ, | |
114 | buf) != SLICE_SIZE) { | |
c3bc4cae | 115 | retval = -1; |
bc769ff8 | 116 | goto exit_up; |
c3bc4cae | 117 | } |
c3bc4cae | 118 | } else { |
bc769ff8 | 119 | for (i = 0; i < SLICE_SIZE; i++) { |
c3bc4cae | 120 | j = i2c_smbus_read_byte(client); |
bc769ff8 | 121 | if (j < 0) { |
c3bc4cae | 122 | retval = -1; |
bc769ff8 | 123 | goto exit_up; |
c3bc4cae | 124 | } |
bc769ff8 | 125 | buf[i] = j; |
c3bc4cae BW |
126 | } |
127 | } | |
bc769ff8 | 128 | data->last_updated[slice] = jiffies; |
129 | data->valid |= (1 << slice); | |
c3bc4cae | 130 | } |
bc769ff8 | 131 | exit_up: |
c3bc4cae | 132 | up(&data->update_lock); |
c3bc4cae BW |
133 | } |
134 | ||
bc769ff8 | 135 | static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj) |
c3bc4cae | 136 | { |
bc769ff8 | 137 | return to_i2c_client(container_of(kobj, struct device, kobj)); |
c3bc4cae BW |
138 | } |
139 | ||
bc769ff8 | 140 | static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off, |
141 | size_t count) | |
c3bc4cae | 142 | { |
bc769ff8 | 143 | struct i2c_client *client = kobj_to_i2c_client(kobj); |
c3bc4cae | 144 | struct max6875_data *data = i2c_get_clientdata(client); |
bc769ff8 | 145 | int slice, max_slice; |
c3bc4cae | 146 | |
bc769ff8 | 147 | if (off > USER_EEPROM_SIZE) |
c3bc4cae | 148 | return 0; |
c3bc4cae | 149 | |
bc769ff8 | 150 | if (off + count > USER_EEPROM_SIZE) |
151 | count = USER_EEPROM_SIZE - off; | |
c3bc4cae | 152 | |
bc769ff8 | 153 | /* refresh slices which contain requested bytes */ |
154 | max_slice = (off + count - 1) >> SLICE_BITS; | |
155 | for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++) | |
156 | max6875_update_slice(client, slice); | |
c3bc4cae | 157 | |
bc769ff8 | 158 | memcpy(buf, &data->data[off], count); |
c3bc4cae | 159 | |
bc769ff8 | 160 | return count; |
c3bc4cae BW |
161 | } |
162 | ||
163 | static struct bin_attribute user_eeprom_attr = { | |
164 | .attr = { | |
bc769ff8 | 165 | .name = "eeprom", |
166 | .mode = S_IRUGO, | |
c3bc4cae BW |
167 | .owner = THIS_MODULE, |
168 | }, | |
bc769ff8 | 169 | .size = USER_EEPROM_SIZE, |
170 | .read = max6875_read, | |
c3bc4cae BW |
171 | }; |
172 | ||
173 | static int max6875_attach_adapter(struct i2c_adapter *adapter) | |
174 | { | |
175 | return i2c_detect(adapter, &addr_data, max6875_detect); | |
176 | } | |
177 | ||
178 | /* This function is called by i2c_detect */ | |
179 | static int max6875_detect(struct i2c_adapter *adapter, int address, int kind) | |
180 | { | |
bc769ff8 | 181 | struct i2c_client *real_client; |
182 | struct i2c_client *fake_client; | |
c3bc4cae BW |
183 | struct max6875_data *data; |
184 | int err = 0; | |
185 | ||
bc769ff8 | 186 | /* Prevent 24rf08 corruption (in case of user error) */ |
0d73adc1 JD |
187 | if (kind < 0) |
188 | i2c_smbus_xfer(adapter, address, 0, 0, 0, | |
189 | I2C_SMBUS_QUICK, NULL); | |
190 | ||
bc769ff8 | 191 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
192 | | I2C_FUNC_SMBUS_READ_BYTE)) | |
193 | return 0; | |
194 | ||
195 | /* Only check even addresses */ | |
196 | if (address & 1) | |
197 | return 0; | |
198 | ||
199 | if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL))) | |
200 | return -ENOMEM; | |
c3bc4cae BW |
201 | memset(data, 0, sizeof(struct max6875_data)); |
202 | ||
bc769ff8 | 203 | /* A fake client is created on the odd address */ |
204 | if (!(fake_client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL))) { | |
205 | err = -ENOMEM; | |
206 | goto exit_kfree1; | |
207 | } | |
208 | memset(fake_client, 0, sizeof(struct i2c_client)); | |
209 | ||
210 | /* Init real i2c_client */ | |
211 | real_client = &data->client; | |
212 | i2c_set_clientdata(real_client, data); | |
213 | real_client->addr = address; | |
214 | real_client->adapter = adapter; | |
215 | real_client->driver = &max6875_driver; | |
216 | real_client->flags = 0; | |
217 | strlcpy(real_client->name, "max6875", I2C_NAME_SIZE); | |
c3bc4cae BW |
218 | init_MUTEX(&data->update_lock); |
219 | ||
bc769ff8 | 220 | /* Init fake client data */ |
221 | /* set the client data to the i2c_client so that it will get freed */ | |
222 | i2c_set_clientdata(fake_client, fake_client); | |
223 | fake_client->addr = address | 1; | |
224 | fake_client->adapter = adapter; | |
225 | fake_client->driver = &max6875_driver; | |
226 | fake_client->flags = 0; | |
227 | strlcpy(fake_client->name, "max6875-dummy", I2C_NAME_SIZE); | |
228 | ||
229 | /* Prevent 24RF08 corruption (in case of user error) */ | |
230 | i2c_smbus_write_quick(real_client, 0); | |
231 | ||
232 | if ((err = i2c_attach_client(real_client)) != 0) | |
233 | goto exit_kfree2; | |
234 | ||
235 | if ((err = i2c_attach_client(fake_client)) != 0) | |
236 | goto exit_detach; | |
237 | ||
238 | sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr); | |
c3bc4cae BW |
239 | |
240 | return 0; | |
241 | ||
bc769ff8 | 242 | exit_detach: |
243 | i2c_detach_client(real_client); | |
244 | exit_kfree2: | |
245 | kfree(fake_client); | |
246 | exit_kfree1: | |
c3bc4cae | 247 | kfree(data); |
c3bc4cae BW |
248 | return err; |
249 | } | |
250 | ||
251 | static int max6875_detach_client(struct i2c_client *client) | |
252 | { | |
253 | int err; | |
254 | ||
255 | err = i2c_detach_client(client); | |
256 | if (err) { | |
bc769ff8 | 257 | dev_err(&client->dev, "i2c_detach_client() failed\n"); |
c3bc4cae BW |
258 | return err; |
259 | } | |
c3bc4cae | 260 | kfree(i2c_get_clientdata(client)); |
c3bc4cae BW |
261 | return 0; |
262 | } | |
263 | ||
264 | static int __init max6875_init(void) | |
265 | { | |
266 | return i2c_add_driver(&max6875_driver); | |
267 | } | |
268 | ||
269 | static void __exit max6875_exit(void) | |
270 | { | |
271 | i2c_del_driver(&max6875_driver); | |
272 | } | |
273 | ||
274 | ||
275 | MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); | |
276 | MODULE_DESCRIPTION("MAX6875 driver"); | |
277 | MODULE_LICENSE("GPL"); | |
278 | ||
279 | module_init(max6875_init); | |
280 | module_exit(max6875_exit); |