1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * lm77.c - Part of lm_sensors, Linux kernel modules for hardware 4 * monitoring 5 * 6 * Copyright (c) 2004 Andras BALI <drewie@freemail.hu> 7 * 8 * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77 9 * is a temperature sensor and thermal window comparator with 0.5 deg 10 * resolution made by National Semiconductor. Complete datasheet can be 11 * obtained at their site: 12 * http://www.national.com/pf/LM/LM77.html 13 */ 14 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/slab.h> 18 #include <linux/jiffies.h> 19 #include <linux/i2c.h> 20 #include <linux/hwmon.h> 21 #include <linux/hwmon-sysfs.h> 22 #include <linux/err.h> 23 #include <linux/mutex.h> 24 25 /* Addresses to scan */ 26 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 27 I2C_CLIENT_END }; 28 29 /* The LM77 registers */ 30 #define LM77_REG_TEMP 0x00 31 #define LM77_REG_CONF 0x01 32 #define LM77_REG_TEMP_HYST 0x02 33 #define LM77_REG_TEMP_CRIT 0x03 34 #define LM77_REG_TEMP_MIN 0x04 35 #define LM77_REG_TEMP_MAX 0x05 36 37 enum temp_index { 38 t_input = 0, 39 t_crit, 40 t_min, 41 t_max, 42 t_hyst, 43 t_num_temp 44 }; 45 46 static const u8 temp_regs[t_num_temp] = { 47 [t_input] = LM77_REG_TEMP, 48 [t_min] = LM77_REG_TEMP_MIN, 49 [t_max] = LM77_REG_TEMP_MAX, 50 [t_crit] = LM77_REG_TEMP_CRIT, 51 [t_hyst] = LM77_REG_TEMP_HYST, 52 }; 53 54 /* Each client has this additional data */ 55 struct lm77_data { 56 struct i2c_client *client; 57 struct mutex update_lock; 58 bool valid; 59 unsigned long last_updated; /* In jiffies */ 60 int temp[t_num_temp]; /* index using temp_index */ 61 u8 alarms; 62 }; 63 64 /* straight from the datasheet */ 65 #define LM77_TEMP_MIN (-55000) 66 #define LM77_TEMP_MAX 125000 67 68 /* 69 * In the temperature registers, the low 3 bits are not part of the 70 * temperature values; they are the status bits. 71 */ 72 static inline s16 LM77_TEMP_TO_REG(int temp) 73 { 74 return (temp / 500) * 8; 75 } 76 77 static inline int LM77_TEMP_FROM_REG(s16 reg) 78 { 79 return (reg / 8) * 500; 80 } 81 82 /* 83 * All registers are word-sized, except for the configuration register. 84 * The LM77 uses the high-byte first convention. 85 */ 86 static u16 lm77_read_value(struct i2c_client *client, u8 reg) 87 { 88 if (reg == LM77_REG_CONF) 89 return i2c_smbus_read_byte_data(client, reg); 90 else 91 return i2c_smbus_read_word_swapped(client, reg); 92 } 93 94 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value) 95 { 96 if (reg == LM77_REG_CONF) 97 return i2c_smbus_write_byte_data(client, reg, value); 98 else 99 return i2c_smbus_write_word_swapped(client, reg, value); 100 } 101 102 static struct lm77_data *lm77_update_device(struct device *dev) 103 { 104 struct lm77_data *data = dev_get_drvdata(dev); 105 struct i2c_client *client = data->client; 106 int i; 107 108 mutex_lock(&data->update_lock); 109 110 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 111 || !data->valid) { 112 dev_dbg(&client->dev, "Starting lm77 update\n"); 113 for (i = 0; i < t_num_temp; i++) { 114 data->temp[i] = 115 LM77_TEMP_FROM_REG(lm77_read_value(client, 116 temp_regs[i])); 117 } 118 data->alarms = 119 lm77_read_value(client, LM77_REG_TEMP) & 0x0007; 120 data->last_updated = jiffies; 121 data->valid = true; 122 } 123 124 mutex_unlock(&data->update_lock); 125 126 return data; 127 } 128 129 /* sysfs stuff */ 130 131 static ssize_t temp_show(struct device *dev, struct device_attribute *devattr, 132 char *buf) 133 { 134 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 135 struct lm77_data *data = lm77_update_device(dev); 136 137 return sprintf(buf, "%d\n", data->temp[attr->index]); 138 } 139 140 static ssize_t temp_hyst_show(struct device *dev, 141 struct device_attribute *devattr, char *buf) 142 { 143 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 144 struct lm77_data *data = lm77_update_device(dev); 145 int nr = attr->index; 146 int temp; 147 148 temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] : 149 data->temp[nr] - data->temp[t_hyst]; 150 151 return sprintf(buf, "%d\n", temp); 152 } 153 154 static ssize_t temp_store(struct device *dev, 155 struct device_attribute *devattr, const char *buf, 156 size_t count) 157 { 158 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 159 struct lm77_data *data = dev_get_drvdata(dev); 160 struct i2c_client *client = data->client; 161 int nr = attr->index; 162 long val; 163 int err; 164 165 err = kstrtol(buf, 10, &val); 166 if (err) 167 return err; 168 169 val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX); 170 mutex_lock(&data->update_lock); 171 data->temp[nr] = val; 172 lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val)); 173 mutex_unlock(&data->update_lock); 174 return count; 175 } 176 177 /* 178 * hysteresis is stored as a relative value on the chip, so it has to be 179 * converted first. 180 */ 181 static ssize_t temp_hyst_store(struct device *dev, 182 struct device_attribute *devattr, 183 const char *buf, size_t count) 184 { 185 struct lm77_data *data = dev_get_drvdata(dev); 186 struct i2c_client *client = data->client; 187 long val; 188 int err; 189 190 err = kstrtol(buf, 10, &val); 191 if (err) 192 return err; 193 194 mutex_lock(&data->update_lock); 195 val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX); 196 data->temp[t_hyst] = val; 197 lm77_write_value(client, LM77_REG_TEMP_HYST, 198 LM77_TEMP_TO_REG(data->temp[t_hyst])); 199 mutex_unlock(&data->update_lock); 200 return count; 201 } 202 203 static ssize_t alarm_show(struct device *dev, struct device_attribute *attr, 204 char *buf) 205 { 206 int bitnr = to_sensor_dev_attr(attr)->index; 207 struct lm77_data *data = lm77_update_device(dev); 208 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1); 209 } 210 211 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input); 212 static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit); 213 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min); 214 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max); 215 216 static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit); 217 static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min); 218 static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max); 219 220 static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2); 221 static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0); 222 static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1); 223 224 static struct attribute *lm77_attrs[] = { 225 &sensor_dev_attr_temp1_input.dev_attr.attr, 226 &sensor_dev_attr_temp1_crit.dev_attr.attr, 227 &sensor_dev_attr_temp1_min.dev_attr.attr, 228 &sensor_dev_attr_temp1_max.dev_attr.attr, 229 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 230 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr, 231 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 232 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 233 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 234 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 235 NULL 236 }; 237 ATTRIBUTE_GROUPS(lm77); 238 239 /* Return 0 if detection is successful, -ENODEV otherwise */ 240 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info) 241 { 242 struct i2c_adapter *adapter = client->adapter; 243 int i, cur, conf, hyst, crit, min, max; 244 245 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | 246 I2C_FUNC_SMBUS_WORD_DATA)) 247 return -ENODEV; 248 249 /* 250 * Here comes the remaining detection. Since the LM77 has no 251 * register dedicated to identification, we have to rely on the 252 * following tricks: 253 * 254 * 1. the high 4 bits represent the sign and thus they should 255 * always be the same 256 * 2. the high 3 bits are unused in the configuration register 257 * 3. addresses 0x06 and 0x07 return the last read value 258 * 4. registers cycling over 8-address boundaries 259 * 260 * Word-sized registers are high-byte first. 261 */ 262 263 /* addresses cycling */ 264 cur = i2c_smbus_read_word_data(client, 0); 265 conf = i2c_smbus_read_byte_data(client, 1); 266 hyst = i2c_smbus_read_word_data(client, 2); 267 crit = i2c_smbus_read_word_data(client, 3); 268 min = i2c_smbus_read_word_data(client, 4); 269 max = i2c_smbus_read_word_data(client, 5); 270 for (i = 8; i <= 0xff; i += 8) { 271 if (i2c_smbus_read_byte_data(client, i + 1) != conf 272 || i2c_smbus_read_word_data(client, i + 2) != hyst 273 || i2c_smbus_read_word_data(client, i + 3) != crit 274 || i2c_smbus_read_word_data(client, i + 4) != min 275 || i2c_smbus_read_word_data(client, i + 5) != max) 276 return -ENODEV; 277 } 278 279 /* sign bits */ 280 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0) 281 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0) 282 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0) 283 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0) 284 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0)) 285 return -ENODEV; 286 287 /* unused bits */ 288 if (conf & 0xe0) 289 return -ENODEV; 290 291 /* 0x06 and 0x07 return the last read value */ 292 cur = i2c_smbus_read_word_data(client, 0); 293 if (i2c_smbus_read_word_data(client, 6) != cur 294 || i2c_smbus_read_word_data(client, 7) != cur) 295 return -ENODEV; 296 hyst = i2c_smbus_read_word_data(client, 2); 297 if (i2c_smbus_read_word_data(client, 6) != hyst 298 || i2c_smbus_read_word_data(client, 7) != hyst) 299 return -ENODEV; 300 min = i2c_smbus_read_word_data(client, 4); 301 if (i2c_smbus_read_word_data(client, 6) != min 302 || i2c_smbus_read_word_data(client, 7) != min) 303 return -ENODEV; 304 305 strscpy(info->type, "lm77", I2C_NAME_SIZE); 306 307 return 0; 308 } 309 310 static void lm77_init_client(struct i2c_client *client) 311 { 312 /* Initialize the LM77 chip - turn off shutdown mode */ 313 int conf = lm77_read_value(client, LM77_REG_CONF); 314 if (conf & 1) 315 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe); 316 } 317 318 static int lm77_probe(struct i2c_client *client) 319 { 320 struct device *dev = &client->dev; 321 struct device *hwmon_dev; 322 struct lm77_data *data; 323 324 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL); 325 if (!data) 326 return -ENOMEM; 327 328 data->client = client; 329 mutex_init(&data->update_lock); 330 331 /* Initialize the LM77 chip */ 332 lm77_init_client(client); 333 334 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 335 data, lm77_groups); 336 return PTR_ERR_OR_ZERO(hwmon_dev); 337 } 338 339 static const struct i2c_device_id lm77_id[] = { 340 { "lm77", 0 }, 341 { } 342 }; 343 MODULE_DEVICE_TABLE(i2c, lm77_id); 344 345 /* This is the driver that will be inserted */ 346 static struct i2c_driver lm77_driver = { 347 .class = I2C_CLASS_HWMON, 348 .driver = { 349 .name = "lm77", 350 }, 351 .probe_new = lm77_probe, 352 .id_table = lm77_id, 353 .detect = lm77_detect, 354 .address_list = normal_i2c, 355 }; 356 357 module_i2c_driver(lm77_driver); 358 359 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>"); 360 MODULE_DESCRIPTION("LM77 driver"); 361 MODULE_LICENSE("GPL"); 362