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 int ntemp = clamp_val(temp, LM77_TEMP_MIN, LM77_TEMP_MAX); 84 return (ntemp / 500) * 8; 85 } 86 87 static inline int LM77_TEMP_FROM_REG(s16 reg) 88 { 89 return (reg / 8) * 500; 90 } 91 92 /* 93 * All registers are word-sized, except for the configuration register. 94 * The LM77 uses the high-byte first convention. 95 */ 96 static u16 lm77_read_value(struct i2c_client *client, u8 reg) 97 { 98 if (reg == LM77_REG_CONF) 99 return i2c_smbus_read_byte_data(client, reg); 100 else 101 return i2c_smbus_read_word_swapped(client, reg); 102 } 103 104 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value) 105 { 106 if (reg == LM77_REG_CONF) 107 return i2c_smbus_write_byte_data(client, reg, value); 108 else 109 return i2c_smbus_write_word_swapped(client, reg, value); 110 } 111 112 static struct lm77_data *lm77_update_device(struct device *dev) 113 { 114 struct lm77_data *data = dev_get_drvdata(dev); 115 struct i2c_client *client = data->client; 116 int i; 117 118 mutex_lock(&data->update_lock); 119 120 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 121 || !data->valid) { 122 dev_dbg(&client->dev, "Starting lm77 update\n"); 123 for (i = 0; i < t_num_temp; i++) { 124 data->temp[i] = 125 LM77_TEMP_FROM_REG(lm77_read_value(client, 126 temp_regs[i])); 127 } 128 data->alarms = 129 lm77_read_value(client, LM77_REG_TEMP) & 0x0007; 130 data->last_updated = jiffies; 131 data->valid = 1; 132 } 133 134 mutex_unlock(&data->update_lock); 135 136 return data; 137 } 138 139 /* sysfs stuff */ 140 141 static ssize_t show_temp(struct device *dev, struct device_attribute *devattr, 142 char *buf) 143 { 144 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 145 struct lm77_data *data = lm77_update_device(dev); 146 147 return sprintf(buf, "%d\n", data->temp[attr->index]); 148 } 149 150 static ssize_t show_temp_hyst(struct device *dev, 151 struct device_attribute *devattr, char *buf) 152 { 153 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 154 struct lm77_data *data = lm77_update_device(dev); 155 int nr = attr->index; 156 int temp; 157 158 temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] : 159 data->temp[nr] - data->temp[t_hyst]; 160 161 return sprintf(buf, "%d\n", temp); 162 } 163 164 static ssize_t set_temp(struct device *dev, struct device_attribute *devattr, 165 const char *buf, 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 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 unsigned long val; 196 int err; 197 198 err = kstrtoul(buf, 10, &val); 199 if (err) 200 return err; 201 202 mutex_lock(&data->update_lock); 203 data->temp[t_hyst] = data->temp[t_crit] - val; 204 lm77_write_value(client, LM77_REG_TEMP_HYST, 205 LM77_TEMP_TO_REG(data->temp[t_hyst])); 206 mutex_unlock(&data->update_lock); 207 return count; 208 } 209 210 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr, 211 char *buf) 212 { 213 int bitnr = to_sensor_dev_attr(attr)->index; 214 struct lm77_data *data = lm77_update_device(dev); 215 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1); 216 } 217 218 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input); 219 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp, 220 t_crit); 221 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 222 t_min); 223 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 224 t_max); 225 226 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, 227 set_temp_hyst, t_crit); 228 static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_hyst, NULL, t_min); 229 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max); 230 231 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2); 232 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0); 233 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1); 234 235 static struct attribute *lm77_attrs[] = { 236 &sensor_dev_attr_temp1_input.dev_attr.attr, 237 &sensor_dev_attr_temp1_crit.dev_attr.attr, 238 &sensor_dev_attr_temp1_min.dev_attr.attr, 239 &sensor_dev_attr_temp1_max.dev_attr.attr, 240 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 241 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr, 242 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 243 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 244 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 245 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 246 NULL 247 }; 248 ATTRIBUTE_GROUPS(lm77); 249 250 /* Return 0 if detection is successful, -ENODEV otherwise */ 251 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info) 252 { 253 struct i2c_adapter *adapter = client->adapter; 254 int i, cur, conf, hyst, crit, min, max; 255 256 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | 257 I2C_FUNC_SMBUS_WORD_DATA)) 258 return -ENODEV; 259 260 /* 261 * Here comes the remaining detection. Since the LM77 has no 262 * register dedicated to identification, we have to rely on the 263 * following tricks: 264 * 265 * 1. the high 4 bits represent the sign and thus they should 266 * always be the same 267 * 2. the high 3 bits are unused in the configuration register 268 * 3. addresses 0x06 and 0x07 return the last read value 269 * 4. registers cycling over 8-address boundaries 270 * 271 * Word-sized registers are high-byte first. 272 */ 273 274 /* addresses cycling */ 275 cur = i2c_smbus_read_word_data(client, 0); 276 conf = i2c_smbus_read_byte_data(client, 1); 277 hyst = i2c_smbus_read_word_data(client, 2); 278 crit = i2c_smbus_read_word_data(client, 3); 279 min = i2c_smbus_read_word_data(client, 4); 280 max = i2c_smbus_read_word_data(client, 5); 281 for (i = 8; i <= 0xff; i += 8) { 282 if (i2c_smbus_read_byte_data(client, i + 1) != conf 283 || i2c_smbus_read_word_data(client, i + 2) != hyst 284 || i2c_smbus_read_word_data(client, i + 3) != crit 285 || i2c_smbus_read_word_data(client, i + 4) != min 286 || i2c_smbus_read_word_data(client, i + 5) != max) 287 return -ENODEV; 288 } 289 290 /* sign bits */ 291 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0) 292 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0) 293 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0) 294 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0) 295 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0)) 296 return -ENODEV; 297 298 /* unused bits */ 299 if (conf & 0xe0) 300 return -ENODEV; 301 302 /* 0x06 and 0x07 return the last read value */ 303 cur = i2c_smbus_read_word_data(client, 0); 304 if (i2c_smbus_read_word_data(client, 6) != cur 305 || i2c_smbus_read_word_data(client, 7) != cur) 306 return -ENODEV; 307 hyst = i2c_smbus_read_word_data(client, 2); 308 if (i2c_smbus_read_word_data(client, 6) != hyst 309 || i2c_smbus_read_word_data(client, 7) != hyst) 310 return -ENODEV; 311 min = i2c_smbus_read_word_data(client, 4); 312 if (i2c_smbus_read_word_data(client, 6) != min 313 || i2c_smbus_read_word_data(client, 7) != min) 314 return -ENODEV; 315 316 strlcpy(info->type, "lm77", I2C_NAME_SIZE); 317 318 return 0; 319 } 320 321 static void lm77_init_client(struct i2c_client *client) 322 { 323 /* Initialize the LM77 chip - turn off shutdown mode */ 324 int conf = lm77_read_value(client, LM77_REG_CONF); 325 if (conf & 1) 326 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe); 327 } 328 329 static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id) 330 { 331 struct device *dev = &client->dev; 332 struct device *hwmon_dev; 333 struct lm77_data *data; 334 335 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL); 336 if (!data) 337 return -ENOMEM; 338 339 data->client = client; 340 mutex_init(&data->update_lock); 341 342 /* Initialize the LM77 chip */ 343 lm77_init_client(client); 344 345 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 346 data, lm77_groups); 347 return PTR_ERR_OR_ZERO(hwmon_dev); 348 } 349 350 static const struct i2c_device_id lm77_id[] = { 351 { "lm77", 0 }, 352 { } 353 }; 354 MODULE_DEVICE_TABLE(i2c, lm77_id); 355 356 /* This is the driver that will be inserted */ 357 static struct i2c_driver lm77_driver = { 358 .class = I2C_CLASS_HWMON, 359 .driver = { 360 .name = "lm77", 361 }, 362 .probe = lm77_probe, 363 .id_table = lm77_id, 364 .detect = lm77_detect, 365 .address_list = normal_i2c, 366 }; 367 368 module_i2c_driver(lm77_driver); 369 370 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>"); 371 MODULE_DESCRIPTION("LM77 driver"); 372 MODULE_LICENSE("GPL"); 373