1 /* 2 * lm77.c - Part of lm_sensors, Linux kernel modules for hardware 3 * monitoring 4 * 5 * Copyright (c) 2004 Andras BALI <drewie@freemail.hu> 6 * 7 * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77 8 * is a temperature sensor and thermal window comparator with 0.5 deg 9 * resolution made by National Semiconductor. Complete datasheet can be 10 * obtained at their site: 11 * http://www.national.com/pf/LM/LM77.html 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License as published by 15 * the Free Software Foundation; either version 2 of the License, or 16 * (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 */ 23 24 #include <linux/module.h> 25 #include <linux/init.h> 26 #include <linux/slab.h> 27 #include <linux/jiffies.h> 28 #include <linux/i2c.h> 29 #include <linux/hwmon.h> 30 #include <linux/hwmon-sysfs.h> 31 #include <linux/err.h> 32 #include <linux/mutex.h> 33 34 /* Addresses to scan */ 35 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 36 I2C_CLIENT_END }; 37 38 /* The LM77 registers */ 39 #define LM77_REG_TEMP 0x00 40 #define LM77_REG_CONF 0x01 41 #define LM77_REG_TEMP_HYST 0x02 42 #define LM77_REG_TEMP_CRIT 0x03 43 #define LM77_REG_TEMP_MIN 0x04 44 #define LM77_REG_TEMP_MAX 0x05 45 46 enum temp_index { 47 t_input = 0, 48 t_crit, 49 t_min, 50 t_max, 51 t_hyst, 52 t_num_temp 53 }; 54 55 static const u8 temp_regs[t_num_temp] = { 56 [t_input] = LM77_REG_TEMP, 57 [t_min] = LM77_REG_TEMP_MIN, 58 [t_max] = LM77_REG_TEMP_MAX, 59 [t_crit] = LM77_REG_TEMP_CRIT, 60 [t_hyst] = LM77_REG_TEMP_HYST, 61 }; 62 63 /* Each client has this additional data */ 64 struct lm77_data { 65 struct i2c_client *client; 66 struct mutex update_lock; 67 char valid; 68 unsigned long last_updated; /* In jiffies */ 69 int temp[t_num_temp]; /* index using temp_index */ 70 u8 alarms; 71 }; 72 73 /* straight from the datasheet */ 74 #define LM77_TEMP_MIN (-55000) 75 #define LM77_TEMP_MAX 125000 76 77 /* 78 * In the temperature registers, the low 3 bits are not part of the 79 * temperature values; they are the status bits. 80 */ 81 static inline s16 LM77_TEMP_TO_REG(int temp) 82 { 83 return (temp / 500) * 8; 84 } 85 86 static inline int LM77_TEMP_FROM_REG(s16 reg) 87 { 88 return (reg / 8) * 500; 89 } 90 91 /* 92 * All registers are word-sized, except for the configuration register. 93 * The LM77 uses the high-byte first convention. 94 */ 95 static u16 lm77_read_value(struct i2c_client *client, u8 reg) 96 { 97 if (reg == LM77_REG_CONF) 98 return i2c_smbus_read_byte_data(client, reg); 99 else 100 return i2c_smbus_read_word_swapped(client, reg); 101 } 102 103 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value) 104 { 105 if (reg == LM77_REG_CONF) 106 return i2c_smbus_write_byte_data(client, reg, value); 107 else 108 return i2c_smbus_write_word_swapped(client, reg, value); 109 } 110 111 static struct lm77_data *lm77_update_device(struct device *dev) 112 { 113 struct lm77_data *data = dev_get_drvdata(dev); 114 struct i2c_client *client = data->client; 115 int i; 116 117 mutex_lock(&data->update_lock); 118 119 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 120 || !data->valid) { 121 dev_dbg(&client->dev, "Starting lm77 update\n"); 122 for (i = 0; i < t_num_temp; i++) { 123 data->temp[i] = 124 LM77_TEMP_FROM_REG(lm77_read_value(client, 125 temp_regs[i])); 126 } 127 data->alarms = 128 lm77_read_value(client, LM77_REG_TEMP) & 0x0007; 129 data->last_updated = jiffies; 130 data->valid = 1; 131 } 132 133 mutex_unlock(&data->update_lock); 134 135 return data; 136 } 137 138 /* sysfs stuff */ 139 140 static ssize_t show_temp(struct device *dev, struct device_attribute *devattr, 141 char *buf) 142 { 143 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 144 struct lm77_data *data = lm77_update_device(dev); 145 146 return sprintf(buf, "%d\n", data->temp[attr->index]); 147 } 148 149 static ssize_t show_temp_hyst(struct device *dev, 150 struct device_attribute *devattr, char *buf) 151 { 152 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 153 struct lm77_data *data = lm77_update_device(dev); 154 int nr = attr->index; 155 int temp; 156 157 temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] : 158 data->temp[nr] - data->temp[t_hyst]; 159 160 return sprintf(buf, "%d\n", temp); 161 } 162 163 static ssize_t set_temp(struct device *dev, struct device_attribute *devattr, 164 const char *buf, size_t count) 165 { 166 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 167 struct lm77_data *data = dev_get_drvdata(dev); 168 struct i2c_client *client = data->client; 169 int nr = attr->index; 170 long val; 171 int err; 172 173 err = kstrtol(buf, 10, &val); 174 if (err) 175 return err; 176 177 val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX); 178 mutex_lock(&data->update_lock); 179 data->temp[nr] = val; 180 lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val)); 181 mutex_unlock(&data->update_lock); 182 return count; 183 } 184 185 /* 186 * hysteresis is stored as a relative value on the chip, so it has to be 187 * converted first. 188 */ 189 static ssize_t set_temp_hyst(struct device *dev, 190 struct device_attribute *devattr, 191 const char *buf, size_t count) 192 { 193 struct lm77_data *data = dev_get_drvdata(dev); 194 struct i2c_client *client = data->client; 195 long val; 196 int err; 197 198 err = kstrtol(buf, 10, &val); 199 if (err) 200 return err; 201 202 mutex_lock(&data->update_lock); 203 val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX); 204 data->temp[t_hyst] = val; 205 lm77_write_value(client, LM77_REG_TEMP_HYST, 206 LM77_TEMP_TO_REG(data->temp[t_hyst])); 207 mutex_unlock(&data->update_lock); 208 return count; 209 } 210 211 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr, 212 char *buf) 213 { 214 int bitnr = to_sensor_dev_attr(attr)->index; 215 struct lm77_data *data = lm77_update_device(dev); 216 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1); 217 } 218 219 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input); 220 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp, 221 t_crit); 222 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 223 t_min); 224 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 225 t_max); 226 227 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, 228 set_temp_hyst, t_crit); 229 static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_hyst, NULL, t_min); 230 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max); 231 232 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2); 233 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0); 234 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1); 235 236 static struct attribute *lm77_attrs[] = { 237 &sensor_dev_attr_temp1_input.dev_attr.attr, 238 &sensor_dev_attr_temp1_crit.dev_attr.attr, 239 &sensor_dev_attr_temp1_min.dev_attr.attr, 240 &sensor_dev_attr_temp1_max.dev_attr.attr, 241 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 242 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr, 243 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 244 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 245 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 246 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 247 NULL 248 }; 249 ATTRIBUTE_GROUPS(lm77); 250 251 /* Return 0 if detection is successful, -ENODEV otherwise */ 252 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info) 253 { 254 struct i2c_adapter *adapter = client->adapter; 255 int i, cur, conf, hyst, crit, min, max; 256 257 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | 258 I2C_FUNC_SMBUS_WORD_DATA)) 259 return -ENODEV; 260 261 /* 262 * Here comes the remaining detection. Since the LM77 has no 263 * register dedicated to identification, we have to rely on the 264 * following tricks: 265 * 266 * 1. the high 4 bits represent the sign and thus they should 267 * always be the same 268 * 2. the high 3 bits are unused in the configuration register 269 * 3. addresses 0x06 and 0x07 return the last read value 270 * 4. registers cycling over 8-address boundaries 271 * 272 * Word-sized registers are high-byte first. 273 */ 274 275 /* addresses cycling */ 276 cur = i2c_smbus_read_word_data(client, 0); 277 conf = i2c_smbus_read_byte_data(client, 1); 278 hyst = i2c_smbus_read_word_data(client, 2); 279 crit = i2c_smbus_read_word_data(client, 3); 280 min = i2c_smbus_read_word_data(client, 4); 281 max = i2c_smbus_read_word_data(client, 5); 282 for (i = 8; i <= 0xff; i += 8) { 283 if (i2c_smbus_read_byte_data(client, i + 1) != conf 284 || i2c_smbus_read_word_data(client, i + 2) != hyst 285 || i2c_smbus_read_word_data(client, i + 3) != crit 286 || i2c_smbus_read_word_data(client, i + 4) != min 287 || i2c_smbus_read_word_data(client, i + 5) != max) 288 return -ENODEV; 289 } 290 291 /* sign bits */ 292 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0) 293 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0) 294 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0) 295 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0) 296 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0)) 297 return -ENODEV; 298 299 /* unused bits */ 300 if (conf & 0xe0) 301 return -ENODEV; 302 303 /* 0x06 and 0x07 return the last read value */ 304 cur = i2c_smbus_read_word_data(client, 0); 305 if (i2c_smbus_read_word_data(client, 6) != cur 306 || i2c_smbus_read_word_data(client, 7) != cur) 307 return -ENODEV; 308 hyst = i2c_smbus_read_word_data(client, 2); 309 if (i2c_smbus_read_word_data(client, 6) != hyst 310 || i2c_smbus_read_word_data(client, 7) != hyst) 311 return -ENODEV; 312 min = i2c_smbus_read_word_data(client, 4); 313 if (i2c_smbus_read_word_data(client, 6) != min 314 || i2c_smbus_read_word_data(client, 7) != min) 315 return -ENODEV; 316 317 strlcpy(info->type, "lm77", I2C_NAME_SIZE); 318 319 return 0; 320 } 321 322 static void lm77_init_client(struct i2c_client *client) 323 { 324 /* Initialize the LM77 chip - turn off shutdown mode */ 325 int conf = lm77_read_value(client, LM77_REG_CONF); 326 if (conf & 1) 327 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe); 328 } 329 330 static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id) 331 { 332 struct device *dev = &client->dev; 333 struct device *hwmon_dev; 334 struct lm77_data *data; 335 336 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL); 337 if (!data) 338 return -ENOMEM; 339 340 data->client = client; 341 mutex_init(&data->update_lock); 342 343 /* Initialize the LM77 chip */ 344 lm77_init_client(client); 345 346 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 347 data, lm77_groups); 348 return PTR_ERR_OR_ZERO(hwmon_dev); 349 } 350 351 static const struct i2c_device_id lm77_id[] = { 352 { "lm77", 0 }, 353 { } 354 }; 355 MODULE_DEVICE_TABLE(i2c, lm77_id); 356 357 /* This is the driver that will be inserted */ 358 static struct i2c_driver lm77_driver = { 359 .class = I2C_CLASS_HWMON, 360 .driver = { 361 .name = "lm77", 362 }, 363 .probe = lm77_probe, 364 .id_table = lm77_id, 365 .detect = lm77_detect, 366 .address_list = normal_i2c, 367 }; 368 369 module_i2c_driver(lm77_driver); 370 371 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>"); 372 MODULE_DESCRIPTION("LM77 driver"); 373 MODULE_LICENSE("GPL"); 374