Commit | Line | Data |
---|---|---|
c3bc4cae | 1 | /* |
6858d498 AA |
2 | * max6875.c - driver for MAX6874/MAX6875 |
3 | * | |
4 | * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com> | |
5 | * | |
6 | * Based on eeprom.c | |
7 | * | |
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 | |
13 | * | |
14 | * This driver makes the user EEPROM available for read. | |
15 | * | |
16 | * The registers & config EEPROM should be accessed via i2c-dev. | |
17 | * | |
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. | |
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 | */ | |
c3bc4cae | 28 | |
c3bc4cae | 29 | #include <linux/kernel.h> |
c3bc4cae BW |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
c3bc4cae | 32 | #include <linux/i2c.h> |
5c085d36 | 33 | #include <linux/mutex.h> |
c3bc4cae | 34 | |
c3bc4cae BW |
35 | /* The MAX6875 can only read/write 16 bytes at a time */ |
36 | #define SLICE_SIZE 16 | |
37 | #define SLICE_BITS 4 | |
38 | ||
c3bc4cae BW |
39 | /* USER EEPROM is at addresses 0x8100 - 0x82FF */ |
40 | #define USER_EEPROM_BASE 0x8100 | |
41 | #define USER_EEPROM_SIZE 0x0200 | |
42 | #define USER_EEPROM_SLICES 32 | |
43 | ||
44 | /* MAX6875 commands */ | |
bc769ff8 | 45 | #define MAX6875_CMD_BLK_READ 0x84 |
c3bc4cae BW |
46 | |
47 | /* Each client has this additional data */ | |
48 | struct max6875_data { | |
bd8d421f | 49 | struct i2c_client *fake_client; |
5c085d36 | 50 | struct mutex update_lock; |
bc769ff8 | 51 | |
52 | u32 valid; | |
53 | u8 data[USER_EEPROM_SIZE]; | |
54 | unsigned long last_updated[USER_EEPROM_SLICES]; | |
c3bc4cae BW |
55 | }; |
56 | ||
bc769ff8 | 57 | static void max6875_update_slice(struct i2c_client *client, int slice) |
c3bc4cae BW |
58 | { |
59 | struct max6875_data *data = i2c_get_clientdata(client); | |
bc769ff8 | 60 | int i, j, addr; |
61 | u8 *buf; | |
c3bc4cae | 62 | |
bc769ff8 | 63 | if (slice >= USER_EEPROM_SLICES) |
64 | return; | |
c3bc4cae | 65 | |
5c085d36 | 66 | mutex_lock(&data->update_lock); |
c3bc4cae | 67 | |
bc769ff8 | 68 | buf = &data->data[slice << SLICE_BITS]; |
69 | ||
70 | if (!(data->valid & (1 << slice)) || | |
71 | time_after(jiffies, data->last_updated[slice])) { | |
72 | ||
a8decc65 | 73 | dev_dbg(&client->dev, "Starting update of slice %u\n", slice); |
c3bc4cae | 74 | |
bc769ff8 | 75 | data->valid &= ~(1 << slice); |
c3bc4cae | 76 | |
bc769ff8 | 77 | addr = USER_EEPROM_BASE + (slice << SLICE_BITS); |
78 | ||
79 | /* select the eeprom address */ | |
80 | if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) { | |
81 | dev_err(&client->dev, "address set failed\n"); | |
bc769ff8 | 82 | goto exit_up; |
c3bc4cae BW |
83 | } |
84 | ||
bc769ff8 | 85 | if (i2c_check_functionality(client->adapter, |
86 | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { | |
87 | if (i2c_smbus_read_i2c_block_data(client, | |
88 | MAX6875_CMD_BLK_READ, | |
4b2643d7 | 89 | SLICE_SIZE, |
bc769ff8 | 90 | buf) != SLICE_SIZE) { |
bc769ff8 | 91 | goto exit_up; |
c3bc4cae | 92 | } |
c3bc4cae | 93 | } else { |
bc769ff8 | 94 | for (i = 0; i < SLICE_SIZE; i++) { |
c3bc4cae | 95 | j = i2c_smbus_read_byte(client); |
bc769ff8 | 96 | if (j < 0) { |
bc769ff8 | 97 | goto exit_up; |
c3bc4cae | 98 | } |
bc769ff8 | 99 | buf[i] = j; |
c3bc4cae BW |
100 | } |
101 | } | |
bc769ff8 | 102 | data->last_updated[slice] = jiffies; |
103 | data->valid |= (1 << slice); | |
c3bc4cae | 104 | } |
bc769ff8 | 105 | exit_up: |
5c085d36 | 106 | mutex_unlock(&data->update_lock); |
c3bc4cae BW |
107 | } |
108 | ||
2c3c8bea | 109 | static ssize_t max6875_read(struct file *filp, struct kobject *kobj, |
91a69029 ZR |
110 | struct bin_attribute *bin_attr, |
111 | char *buf, loff_t off, size_t count) | |
c3bc4cae | 112 | { |
bc769ff8 | 113 | struct i2c_client *client = kobj_to_i2c_client(kobj); |
c3bc4cae | 114 | struct max6875_data *data = i2c_get_clientdata(client); |
bc769ff8 | 115 | int slice, max_slice; |
c3bc4cae | 116 | |
bc769ff8 | 117 | /* refresh slices which contain requested bytes */ |
118 | max_slice = (off + count - 1) >> SLICE_BITS; | |
119 | for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++) | |
120 | max6875_update_slice(client, slice); | |
c3bc4cae | 121 | |
bc769ff8 | 122 | memcpy(buf, &data->data[off], count); |
c3bc4cae | 123 | |
bc769ff8 | 124 | return count; |
c3bc4cae BW |
125 | } |
126 | ||
127 | static struct bin_attribute user_eeprom_attr = { | |
128 | .attr = { | |
bc769ff8 | 129 | .name = "eeprom", |
130 | .mode = S_IRUGO, | |
c3bc4cae | 131 | }, |
bc769ff8 | 132 | .size = USER_EEPROM_SIZE, |
133 | .read = max6875_read, | |
c3bc4cae BW |
134 | }; |
135 | ||
b835d7fb JD |
136 | static int max6875_probe(struct i2c_client *client, |
137 | const struct i2c_device_id *id) | |
c3bc4cae | 138 | { |
bd8d421f | 139 | struct i2c_adapter *adapter = client->adapter; |
b835d7fb JD |
140 | struct max6875_data *data; |
141 | int err; | |
c3bc4cae | 142 | |
17f990c8 | 143 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
bc769ff8 | 144 | | I2C_FUNC_SMBUS_READ_BYTE)) |
bd8d421f | 145 | return -ENODEV; |
bc769ff8 | 146 | |
b835d7fb | 147 | /* Only bind to even addresses */ |
bd8d421f JD |
148 | if (client->addr & 1) |
149 | return -ENODEV; | |
150 | ||
5263ebb5 | 151 | if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL))) |
bc769ff8 | 152 | return -ENOMEM; |
c3bc4cae | 153 | |
bc769ff8 | 154 | /* A fake client is created on the odd address */ |
bd8d421f JD |
155 | data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1); |
156 | if (!data->fake_client) { | |
bc769ff8 | 157 | err = -ENOMEM; |
bd8d421f | 158 | goto exit_kfree; |
bc769ff8 | 159 | } |
bc769ff8 | 160 | |
161 | /* Init real i2c_client */ | |
bd8d421f | 162 | i2c_set_clientdata(client, data); |
5c085d36 | 163 | mutex_init(&data->update_lock); |
c3bc4cae | 164 | |
bd8d421f | 165 | err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr); |
7d9db67f | 166 | if (err) |
bd8d421f | 167 | goto exit_remove_fake; |
c3bc4cae BW |
168 | |
169 | return 0; | |
170 | ||
bd8d421f JD |
171 | exit_remove_fake: |
172 | i2c_unregister_device(data->fake_client); | |
173 | exit_kfree: | |
c3bc4cae | 174 | kfree(data); |
c3bc4cae BW |
175 | return err; |
176 | } | |
177 | ||
bd8d421f | 178 | static int max6875_remove(struct i2c_client *client) |
c3bc4cae | 179 | { |
7d9db67f JD |
180 | struct max6875_data *data = i2c_get_clientdata(client); |
181 | ||
bd8d421f | 182 | i2c_unregister_device(data->fake_client); |
c3bc4cae | 183 | |
bd8d421f JD |
184 | sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr); |
185 | kfree(data); | |
7d9db67f | 186 | |
c3bc4cae BW |
187 | return 0; |
188 | } | |
189 | ||
bd8d421f JD |
190 | static const struct i2c_device_id max6875_id[] = { |
191 | { "max6875", 0 }, | |
192 | { } | |
193 | }; | |
c49c1f08 | 194 | MODULE_DEVICE_TABLE(i2c, max6875_id); |
bd8d421f JD |
195 | |
196 | static struct i2c_driver max6875_driver = { | |
197 | .driver = { | |
198 | .name = "max6875", | |
199 | }, | |
200 | .probe = max6875_probe, | |
201 | .remove = max6875_remove, | |
202 | .id_table = max6875_id, | |
bd8d421f JD |
203 | }; |
204 | ||
a64fe2ed | 205 | module_i2c_driver(max6875_driver); |
c3bc4cae BW |
206 | |
207 | MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); | |
208 | MODULE_DESCRIPTION("MAX6875 driver"); | |
209 | MODULE_LICENSE("GPL"); |