1 /* 2 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller 3 * 4 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; version 2 of the License. 9 * 10 * This driver is based on the ds1621 and ina209 drivers. 11 * 12 * Datasheet: 13 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/init.h> 19 #include <linux/err.h> 20 #include <linux/slab.h> 21 #include <linux/i2c.h> 22 #include <linux/hwmon.h> 23 #include <linux/hwmon-sysfs.h> 24 #include <linux/jiffies.h> 25 #include <linux/i2c/ltc4245.h> 26 27 /* Here are names of the chip's registers (a.k.a. commands) */ 28 enum ltc4245_cmd { 29 LTC4245_STATUS = 0x00, /* readonly */ 30 LTC4245_ALERT = 0x01, 31 LTC4245_CONTROL = 0x02, 32 LTC4245_ON = 0x03, 33 LTC4245_FAULT1 = 0x04, 34 LTC4245_FAULT2 = 0x05, 35 LTC4245_GPIO = 0x06, 36 LTC4245_ADCADR = 0x07, 37 38 LTC4245_12VIN = 0x10, 39 LTC4245_12VSENSE = 0x11, 40 LTC4245_12VOUT = 0x12, 41 LTC4245_5VIN = 0x13, 42 LTC4245_5VSENSE = 0x14, 43 LTC4245_5VOUT = 0x15, 44 LTC4245_3VIN = 0x16, 45 LTC4245_3VSENSE = 0x17, 46 LTC4245_3VOUT = 0x18, 47 LTC4245_VEEIN = 0x19, 48 LTC4245_VEESENSE = 0x1a, 49 LTC4245_VEEOUT = 0x1b, 50 LTC4245_GPIOADC = 0x1c, 51 }; 52 53 struct ltc4245_data { 54 struct device *hwmon_dev; 55 56 struct mutex update_lock; 57 bool valid; 58 unsigned long last_updated; /* in jiffies */ 59 60 /* Control registers */ 61 u8 cregs[0x08]; 62 63 /* Voltage registers */ 64 u8 vregs[0x0d]; 65 66 /* GPIO ADC registers */ 67 bool use_extra_gpios; 68 int gpios[3]; 69 }; 70 71 /* 72 * Update the readings from the GPIO pins. If the driver has been configured to 73 * sample all GPIO's as analog voltages, a round-robin sampling method is used. 74 * Otherwise, only the configured GPIO pin is sampled. 75 * 76 * LOCKING: must hold data->update_lock 77 */ 78 static void ltc4245_update_gpios(struct device *dev) 79 { 80 struct i2c_client *client = to_i2c_client(dev); 81 struct ltc4245_data *data = i2c_get_clientdata(client); 82 u8 gpio_curr, gpio_next, gpio_reg; 83 int i; 84 85 /* no extra gpio support, we're basically done */ 86 if (!data->use_extra_gpios) { 87 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; 88 return; 89 } 90 91 /* 92 * If the last reading was too long ago, then we mark all old GPIO 93 * readings as stale by setting them to -EAGAIN 94 */ 95 if (time_after(jiffies, data->last_updated + 5 * HZ)) { 96 dev_dbg(&client->dev, "Marking GPIOs invalid\n"); 97 for (i = 0; i < ARRAY_SIZE(data->gpios); i++) 98 data->gpios[i] = -EAGAIN; 99 } 100 101 /* 102 * Get the current GPIO pin 103 * 104 * The datasheet calls these GPIO[1-3], but we'll calculate the zero 105 * based array index instead, and call them GPIO[0-2]. This is much 106 * easier to think about. 107 */ 108 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6; 109 if (gpio_curr > 0) 110 gpio_curr -= 1; 111 112 /* Read the GPIO voltage from the GPIOADC register */ 113 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10]; 114 115 /* Find the next GPIO pin to read */ 116 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios); 117 118 /* 119 * Calculate the correct setting for the GPIO register so it will 120 * sample the next GPIO pin 121 */ 122 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6); 123 124 /* Update the GPIO register */ 125 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg); 126 127 /* Update saved data */ 128 data->cregs[LTC4245_GPIO] = gpio_reg; 129 } 130 131 static struct ltc4245_data *ltc4245_update_device(struct device *dev) 132 { 133 struct i2c_client *client = to_i2c_client(dev); 134 struct ltc4245_data *data = i2c_get_clientdata(client); 135 s32 val; 136 int i; 137 138 mutex_lock(&data->update_lock); 139 140 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { 141 142 dev_dbg(&client->dev, "Starting ltc4245 update\n"); 143 144 /* Read control registers -- 0x00 to 0x07 */ 145 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { 146 val = i2c_smbus_read_byte_data(client, i); 147 if (unlikely(val < 0)) 148 data->cregs[i] = 0; 149 else 150 data->cregs[i] = val; 151 } 152 153 /* Read voltage registers -- 0x10 to 0x1c */ 154 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { 155 val = i2c_smbus_read_byte_data(client, i+0x10); 156 if (unlikely(val < 0)) 157 data->vregs[i] = 0; 158 else 159 data->vregs[i] = val; 160 } 161 162 /* Update GPIO readings */ 163 ltc4245_update_gpios(dev); 164 165 data->last_updated = jiffies; 166 data->valid = 1; 167 } 168 169 mutex_unlock(&data->update_lock); 170 171 return data; 172 } 173 174 /* Return the voltage from the given register in millivolts */ 175 static int ltc4245_get_voltage(struct device *dev, u8 reg) 176 { 177 struct ltc4245_data *data = ltc4245_update_device(dev); 178 const u8 regval = data->vregs[reg - 0x10]; 179 u32 voltage = 0; 180 181 switch (reg) { 182 case LTC4245_12VIN: 183 case LTC4245_12VOUT: 184 voltage = regval * 55; 185 break; 186 case LTC4245_5VIN: 187 case LTC4245_5VOUT: 188 voltage = regval * 22; 189 break; 190 case LTC4245_3VIN: 191 case LTC4245_3VOUT: 192 voltage = regval * 15; 193 break; 194 case LTC4245_VEEIN: 195 case LTC4245_VEEOUT: 196 voltage = regval * -55; 197 break; 198 case LTC4245_GPIOADC: 199 voltage = regval * 10; 200 break; 201 default: 202 /* If we get here, the developer messed up */ 203 WARN_ON_ONCE(1); 204 break; 205 } 206 207 return voltage; 208 } 209 210 /* Return the current in the given sense register in milliAmperes */ 211 static unsigned int ltc4245_get_current(struct device *dev, u8 reg) 212 { 213 struct ltc4245_data *data = ltc4245_update_device(dev); 214 const u8 regval = data->vregs[reg - 0x10]; 215 unsigned int voltage; 216 unsigned int curr; 217 218 /* 219 * The strange looking conversions that follow are fixed-point 220 * math, since we cannot do floating point in the kernel. 221 * 222 * Step 1: convert sense register to microVolts 223 * Step 2: convert voltage to milliAmperes 224 * 225 * If you play around with the V=IR equation, you come up with 226 * the following: X uV / Y mOhm == Z mA 227 * 228 * With the resistors that are fractions of a milliOhm, we multiply 229 * the voltage and resistance by 10, to shift the decimal point. 230 * Now we can use the normal division operator again. 231 */ 232 233 switch (reg) { 234 case LTC4245_12VSENSE: 235 voltage = regval * 250; /* voltage in uV */ 236 curr = voltage / 50; /* sense resistor 50 mOhm */ 237 break; 238 case LTC4245_5VSENSE: 239 voltage = regval * 125; /* voltage in uV */ 240 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ 241 break; 242 case LTC4245_3VSENSE: 243 voltage = regval * 125; /* voltage in uV */ 244 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ 245 break; 246 case LTC4245_VEESENSE: 247 voltage = regval * 250; /* voltage in uV */ 248 curr = voltage / 100; /* sense resistor 100 mOhm */ 249 break; 250 default: 251 /* If we get here, the developer messed up */ 252 WARN_ON_ONCE(1); 253 curr = 0; 254 break; 255 } 256 257 return curr; 258 } 259 260 static ssize_t ltc4245_show_voltage(struct device *dev, 261 struct device_attribute *da, 262 char *buf) 263 { 264 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 265 const int voltage = ltc4245_get_voltage(dev, attr->index); 266 267 return snprintf(buf, PAGE_SIZE, "%d\n", voltage); 268 } 269 270 static ssize_t ltc4245_show_current(struct device *dev, 271 struct device_attribute *da, 272 char *buf) 273 { 274 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 275 const unsigned int curr = ltc4245_get_current(dev, attr->index); 276 277 return snprintf(buf, PAGE_SIZE, "%u\n", curr); 278 } 279 280 static ssize_t ltc4245_show_power(struct device *dev, 281 struct device_attribute *da, 282 char *buf) 283 { 284 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 285 const unsigned int curr = ltc4245_get_current(dev, attr->index); 286 const int output_voltage = ltc4245_get_voltage(dev, attr->index+1); 287 288 /* current in mA * voltage in mV == power in uW */ 289 const unsigned int power = abs(output_voltage * curr); 290 291 return snprintf(buf, PAGE_SIZE, "%u\n", power); 292 } 293 294 static ssize_t ltc4245_show_alarm(struct device *dev, 295 struct device_attribute *da, 296 char *buf) 297 { 298 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da); 299 struct ltc4245_data *data = ltc4245_update_device(dev); 300 const u8 reg = data->cregs[attr->index]; 301 const u32 mask = attr->nr; 302 303 return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0); 304 } 305 306 static ssize_t ltc4245_show_gpio(struct device *dev, 307 struct device_attribute *da, 308 char *buf) 309 { 310 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 311 struct ltc4245_data *data = ltc4245_update_device(dev); 312 int val = data->gpios[attr->index]; 313 314 /* handle stale GPIO's */ 315 if (val < 0) 316 return val; 317 318 /* Convert to millivolts and print */ 319 return snprintf(buf, PAGE_SIZE, "%u\n", val * 10); 320 } 321 322 /* 323 * These macros are used below in constructing device attribute objects 324 * for use with sysfs_create_group() to make a sysfs device file 325 * for each register. 326 */ 327 328 #define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \ 329 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 330 ltc4245_show_voltage, NULL, ltc4245_cmd_idx) 331 332 #define LTC4245_CURRENT(name, ltc4245_cmd_idx) \ 333 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 334 ltc4245_show_current, NULL, ltc4245_cmd_idx) 335 336 #define LTC4245_POWER(name, ltc4245_cmd_idx) \ 337 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 338 ltc4245_show_power, NULL, ltc4245_cmd_idx) 339 340 #define LTC4245_ALARM(name, mask, reg) \ 341 static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \ 342 ltc4245_show_alarm, NULL, (mask), reg) 343 344 #define LTC4245_GPIO_VOLTAGE(name, gpio_num) \ 345 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 346 ltc4245_show_gpio, NULL, gpio_num) 347 348 /* Construct a sensor_device_attribute structure for each register */ 349 350 /* Input voltages */ 351 LTC4245_VOLTAGE(in1_input, LTC4245_12VIN); 352 LTC4245_VOLTAGE(in2_input, LTC4245_5VIN); 353 LTC4245_VOLTAGE(in3_input, LTC4245_3VIN); 354 LTC4245_VOLTAGE(in4_input, LTC4245_VEEIN); 355 356 /* Input undervoltage alarms */ 357 LTC4245_ALARM(in1_min_alarm, (1 << 0), LTC4245_FAULT1); 358 LTC4245_ALARM(in2_min_alarm, (1 << 1), LTC4245_FAULT1); 359 LTC4245_ALARM(in3_min_alarm, (1 << 2), LTC4245_FAULT1); 360 LTC4245_ALARM(in4_min_alarm, (1 << 3), LTC4245_FAULT1); 361 362 /* Currents (via sense resistor) */ 363 LTC4245_CURRENT(curr1_input, LTC4245_12VSENSE); 364 LTC4245_CURRENT(curr2_input, LTC4245_5VSENSE); 365 LTC4245_CURRENT(curr3_input, LTC4245_3VSENSE); 366 LTC4245_CURRENT(curr4_input, LTC4245_VEESENSE); 367 368 /* Overcurrent alarms */ 369 LTC4245_ALARM(curr1_max_alarm, (1 << 4), LTC4245_FAULT1); 370 LTC4245_ALARM(curr2_max_alarm, (1 << 5), LTC4245_FAULT1); 371 LTC4245_ALARM(curr3_max_alarm, (1 << 6), LTC4245_FAULT1); 372 LTC4245_ALARM(curr4_max_alarm, (1 << 7), LTC4245_FAULT1); 373 374 /* Output voltages */ 375 LTC4245_VOLTAGE(in5_input, LTC4245_12VOUT); 376 LTC4245_VOLTAGE(in6_input, LTC4245_5VOUT); 377 LTC4245_VOLTAGE(in7_input, LTC4245_3VOUT); 378 LTC4245_VOLTAGE(in8_input, LTC4245_VEEOUT); 379 380 /* Power Bad alarms */ 381 LTC4245_ALARM(in5_min_alarm, (1 << 0), LTC4245_FAULT2); 382 LTC4245_ALARM(in6_min_alarm, (1 << 1), LTC4245_FAULT2); 383 LTC4245_ALARM(in7_min_alarm, (1 << 2), LTC4245_FAULT2); 384 LTC4245_ALARM(in8_min_alarm, (1 << 3), LTC4245_FAULT2); 385 386 /* GPIO voltages */ 387 LTC4245_GPIO_VOLTAGE(in9_input, 0); 388 LTC4245_GPIO_VOLTAGE(in10_input, 1); 389 LTC4245_GPIO_VOLTAGE(in11_input, 2); 390 391 /* Power Consumption (virtual) */ 392 LTC4245_POWER(power1_input, LTC4245_12VSENSE); 393 LTC4245_POWER(power2_input, LTC4245_5VSENSE); 394 LTC4245_POWER(power3_input, LTC4245_3VSENSE); 395 LTC4245_POWER(power4_input, LTC4245_VEESENSE); 396 397 /* 398 * Finally, construct an array of pointers to members of the above objects, 399 * as required for sysfs_create_group() 400 */ 401 static struct attribute *ltc4245_std_attributes[] = { 402 &sensor_dev_attr_in1_input.dev_attr.attr, 403 &sensor_dev_attr_in2_input.dev_attr.attr, 404 &sensor_dev_attr_in3_input.dev_attr.attr, 405 &sensor_dev_attr_in4_input.dev_attr.attr, 406 407 &sensor_dev_attr_in1_min_alarm.dev_attr.attr, 408 &sensor_dev_attr_in2_min_alarm.dev_attr.attr, 409 &sensor_dev_attr_in3_min_alarm.dev_attr.attr, 410 &sensor_dev_attr_in4_min_alarm.dev_attr.attr, 411 412 &sensor_dev_attr_curr1_input.dev_attr.attr, 413 &sensor_dev_attr_curr2_input.dev_attr.attr, 414 &sensor_dev_attr_curr3_input.dev_attr.attr, 415 &sensor_dev_attr_curr4_input.dev_attr.attr, 416 417 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, 418 &sensor_dev_attr_curr2_max_alarm.dev_attr.attr, 419 &sensor_dev_attr_curr3_max_alarm.dev_attr.attr, 420 &sensor_dev_attr_curr4_max_alarm.dev_attr.attr, 421 422 &sensor_dev_attr_in5_input.dev_attr.attr, 423 &sensor_dev_attr_in6_input.dev_attr.attr, 424 &sensor_dev_attr_in7_input.dev_attr.attr, 425 &sensor_dev_attr_in8_input.dev_attr.attr, 426 427 &sensor_dev_attr_in5_min_alarm.dev_attr.attr, 428 &sensor_dev_attr_in6_min_alarm.dev_attr.attr, 429 &sensor_dev_attr_in7_min_alarm.dev_attr.attr, 430 &sensor_dev_attr_in8_min_alarm.dev_attr.attr, 431 432 &sensor_dev_attr_in9_input.dev_attr.attr, 433 434 &sensor_dev_attr_power1_input.dev_attr.attr, 435 &sensor_dev_attr_power2_input.dev_attr.attr, 436 &sensor_dev_attr_power3_input.dev_attr.attr, 437 &sensor_dev_attr_power4_input.dev_attr.attr, 438 439 NULL, 440 }; 441 442 static struct attribute *ltc4245_gpio_attributes[] = { 443 &sensor_dev_attr_in10_input.dev_attr.attr, 444 &sensor_dev_attr_in11_input.dev_attr.attr, 445 NULL, 446 }; 447 448 static const struct attribute_group ltc4245_std_group = { 449 .attrs = ltc4245_std_attributes, 450 }; 451 452 static const struct attribute_group ltc4245_gpio_group = { 453 .attrs = ltc4245_gpio_attributes, 454 }; 455 456 static int ltc4245_sysfs_create_groups(struct i2c_client *client) 457 { 458 struct ltc4245_data *data = i2c_get_clientdata(client); 459 struct device *dev = &client->dev; 460 int ret; 461 462 /* register the standard sysfs attributes */ 463 ret = sysfs_create_group(&dev->kobj, <c4245_std_group); 464 if (ret) { 465 dev_err(dev, "unable to register standard attributes\n"); 466 return ret; 467 } 468 469 /* if we're using the extra gpio support, register it's attributes */ 470 if (data->use_extra_gpios) { 471 ret = sysfs_create_group(&dev->kobj, <c4245_gpio_group); 472 if (ret) { 473 dev_err(dev, "unable to register gpio attributes\n"); 474 sysfs_remove_group(&dev->kobj, <c4245_std_group); 475 return ret; 476 } 477 } 478 479 return 0; 480 } 481 482 static void ltc4245_sysfs_remove_groups(struct i2c_client *client) 483 { 484 struct ltc4245_data *data = i2c_get_clientdata(client); 485 struct device *dev = &client->dev; 486 487 if (data->use_extra_gpios) 488 sysfs_remove_group(&dev->kobj, <c4245_gpio_group); 489 490 sysfs_remove_group(&dev->kobj, <c4245_std_group); 491 } 492 493 static bool ltc4245_use_extra_gpios(struct i2c_client *client) 494 { 495 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 496 #ifdef CONFIG_OF 497 struct device_node *np = client->dev.of_node; 498 #endif 499 500 /* prefer platform data */ 501 if (pdata) 502 return pdata->use_extra_gpios; 503 504 #ifdef CONFIG_OF 505 /* fallback on OF */ 506 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL)) 507 return true; 508 #endif 509 510 return false; 511 } 512 513 static int ltc4245_probe(struct i2c_client *client, 514 const struct i2c_device_id *id) 515 { 516 struct i2c_adapter *adapter = client->adapter; 517 struct ltc4245_data *data; 518 int ret; 519 520 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 521 return -ENODEV; 522 523 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 524 if (!data) 525 return -ENOMEM; 526 527 i2c_set_clientdata(client, data); 528 mutex_init(&data->update_lock); 529 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 530 531 /* Initialize the LTC4245 chip */ 532 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 533 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 534 535 /* Register sysfs hooks */ 536 ret = ltc4245_sysfs_create_groups(client); 537 if (ret) 538 return ret; 539 540 data->hwmon_dev = hwmon_device_register(&client->dev); 541 if (IS_ERR(data->hwmon_dev)) { 542 ret = PTR_ERR(data->hwmon_dev); 543 goto out_hwmon_device_register; 544 } 545 546 return 0; 547 548 out_hwmon_device_register: 549 ltc4245_sysfs_remove_groups(client); 550 return ret; 551 } 552 553 static int ltc4245_remove(struct i2c_client *client) 554 { 555 struct ltc4245_data *data = i2c_get_clientdata(client); 556 557 hwmon_device_unregister(data->hwmon_dev); 558 ltc4245_sysfs_remove_groups(client); 559 560 return 0; 561 } 562 563 static const struct i2c_device_id ltc4245_id[] = { 564 { "ltc4245", 0 }, 565 { } 566 }; 567 MODULE_DEVICE_TABLE(i2c, ltc4245_id); 568 569 /* This is the driver that will be inserted */ 570 static struct i2c_driver ltc4245_driver = { 571 .driver = { 572 .name = "ltc4245", 573 }, 574 .probe = ltc4245_probe, 575 .remove = ltc4245_remove, 576 .id_table = ltc4245_id, 577 }; 578 579 module_i2c_driver(ltc4245_driver); 580 581 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 582 MODULE_DESCRIPTION("LTC4245 driver"); 583 MODULE_LICENSE("GPL"); 584