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 temp_show(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 temp_hyst_show(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 temp_store(struct device *dev, 164 struct device_attribute *devattr, const char *buf, 165 size_t count) 166 { 167 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 168 struct lm77_data *data = dev_get_drvdata(dev); 169 struct i2c_client *client = data->client; 170 int nr = attr->index; 171 long val; 172 int err; 173 174 err = kstrtol(buf, 10, &val); 175 if (err) 176 return err; 177 178 val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX); 179 mutex_lock(&data->update_lock); 180 data->temp[nr] = val; 181 lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val)); 182 mutex_unlock(&data->update_lock); 183 return count; 184 } 185 186 /* 187 * hysteresis is stored as a relative value on the chip, so it has to be 188 * converted first. 189 */ 190 static ssize_t temp_hyst_store(struct device *dev, 191 struct device_attribute *devattr, 192 const char *buf, size_t count) 193 { 194 struct lm77_data *data = dev_get_drvdata(dev); 195 struct i2c_client *client = data->client; 196 long val; 197 int err; 198 199 err = kstrtol(buf, 10, &val); 200 if (err) 201 return err; 202 203 mutex_lock(&data->update_lock); 204 val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX); 205 data->temp[t_hyst] = val; 206 lm77_write_value(client, LM77_REG_TEMP_HYST, 207 LM77_TEMP_TO_REG(data->temp[t_hyst])); 208 mutex_unlock(&data->update_lock); 209 return count; 210 } 211 212 static ssize_t alarm_show(struct device *dev, struct device_attribute *attr, 213 char *buf) 214 { 215 int bitnr = to_sensor_dev_attr(attr)->index; 216 struct lm77_data *data = lm77_update_device(dev); 217 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1); 218 } 219 220 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input); 221 static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit); 222 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min); 223 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max); 224 225 static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit); 226 static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min); 227 static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max); 228 229 static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2); 230 static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0); 231 static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1); 232 233 static struct attribute *lm77_attrs[] = { 234 &sensor_dev_attr_temp1_input.dev_attr.attr, 235 &sensor_dev_attr_temp1_crit.dev_attr.attr, 236 &sensor_dev_attr_temp1_min.dev_attr.attr, 237 &sensor_dev_attr_temp1_max.dev_attr.attr, 238 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 239 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr, 240 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 241 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 242 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 243 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 244 NULL 245 }; 246 ATTRIBUTE_GROUPS(lm77); 247 248 /* Return 0 if detection is successful, -ENODEV otherwise */ 249 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info) 250 { 251 struct i2c_adapter *adapter = client->adapter; 252 int i, cur, conf, hyst, crit, min, max; 253 254 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | 255 I2C_FUNC_SMBUS_WORD_DATA)) 256 return -ENODEV; 257 258 /* 259 * Here comes the remaining detection. Since the LM77 has no 260 * register dedicated to identification, we have to rely on the 261 * following tricks: 262 * 263 * 1. the high 4 bits represent the sign and thus they should 264 * always be the same 265 * 2. the high 3 bits are unused in the configuration register 266 * 3. addresses 0x06 and 0x07 return the last read value 267 * 4. registers cycling over 8-address boundaries 268 * 269 * Word-sized registers are high-byte first. 270 */ 271 272 /* addresses cycling */ 273 cur = i2c_smbus_read_word_data(client, 0); 274 conf = i2c_smbus_read_byte_data(client, 1); 275 hyst = i2c_smbus_read_word_data(client, 2); 276 crit = i2c_smbus_read_word_data(client, 3); 277 min = i2c_smbus_read_word_data(client, 4); 278 max = i2c_smbus_read_word_data(client, 5); 279 for (i = 8; i <= 0xff; i += 8) { 280 if (i2c_smbus_read_byte_data(client, i + 1) != conf 281 || i2c_smbus_read_word_data(client, i + 2) != hyst 282 || i2c_smbus_read_word_data(client, i + 3) != crit 283 || i2c_smbus_read_word_data(client, i + 4) != min 284 || i2c_smbus_read_word_data(client, i + 5) != max) 285 return -ENODEV; 286 } 287 288 /* sign bits */ 289 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0) 290 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0) 291 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0) 292 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0) 293 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0)) 294 return -ENODEV; 295 296 /* unused bits */ 297 if (conf & 0xe0) 298 return -ENODEV; 299 300 /* 0x06 and 0x07 return the last read value */ 301 cur = i2c_smbus_read_word_data(client, 0); 302 if (i2c_smbus_read_word_data(client, 6) != cur 303 || i2c_smbus_read_word_data(client, 7) != cur) 304 return -ENODEV; 305 hyst = i2c_smbus_read_word_data(client, 2); 306 if (i2c_smbus_read_word_data(client, 6) != hyst 307 || i2c_smbus_read_word_data(client, 7) != hyst) 308 return -ENODEV; 309 min = i2c_smbus_read_word_data(client, 4); 310 if (i2c_smbus_read_word_data(client, 6) != min 311 || i2c_smbus_read_word_data(client, 7) != min) 312 return -ENODEV; 313 314 strlcpy(info->type, "lm77", I2C_NAME_SIZE); 315 316 return 0; 317 } 318 319 static void lm77_init_client(struct i2c_client *client) 320 { 321 /* Initialize the LM77 chip - turn off shutdown mode */ 322 int conf = lm77_read_value(client, LM77_REG_CONF); 323 if (conf & 1) 324 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe); 325 } 326 327 static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id) 328 { 329 struct device *dev = &client->dev; 330 struct device *hwmon_dev; 331 struct lm77_data *data; 332 333 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL); 334 if (!data) 335 return -ENOMEM; 336 337 data->client = client; 338 mutex_init(&data->update_lock); 339 340 /* Initialize the LM77 chip */ 341 lm77_init_client(client); 342 343 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 344 data, lm77_groups); 345 return PTR_ERR_OR_ZERO(hwmon_dev); 346 } 347 348 static const struct i2c_device_id lm77_id[] = { 349 { "lm77", 0 }, 350 { } 351 }; 352 MODULE_DEVICE_TABLE(i2c, lm77_id); 353 354 /* This is the driver that will be inserted */ 355 static struct i2c_driver lm77_driver = { 356 .class = I2C_CLASS_HWMON, 357 .driver = { 358 .name = "lm77", 359 }, 360 .probe = lm77_probe, 361 .id_table = lm77_id, 362 .detect = lm77_detect, 363 .address_list = normal_i2c, 364 }; 365 366 module_i2c_driver(lm77_driver); 367 368 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>"); 369 MODULE_DESCRIPTION("LM77 driver"); 370 MODULE_LICENSE("GPL"); 371