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/i2c/ltc4245.h> 25 26/* Here are names of the chip's registers (a.k.a. commands) */ 27enum ltc4245_cmd { 28 LTC4245_STATUS = 0x00, /* readonly */ 29 LTC4245_ALERT = 0x01, 30 LTC4245_CONTROL = 0x02, 31 LTC4245_ON = 0x03, 32 LTC4245_FAULT1 = 0x04, 33 LTC4245_FAULT2 = 0x05, 34 LTC4245_GPIO = 0x06, 35 LTC4245_ADCADR = 0x07, 36 37 LTC4245_12VIN = 0x10, 38 LTC4245_12VSENSE = 0x11, 39 LTC4245_12VOUT = 0x12, 40 LTC4245_5VIN = 0x13, 41 LTC4245_5VSENSE = 0x14, 42 LTC4245_5VOUT = 0x15, 43 LTC4245_3VIN = 0x16, 44 LTC4245_3VSENSE = 0x17, 45 LTC4245_3VOUT = 0x18, 46 LTC4245_VEEIN = 0x19, 47 LTC4245_VEESENSE = 0x1a, 48 LTC4245_VEEOUT = 0x1b, 49 LTC4245_GPIOADC = 0x1c, 50}; 51 52struct ltc4245_data { 53 struct device *hwmon_dev; 54 55 struct mutex update_lock; 56 bool valid; 57 unsigned long last_updated; /* in jiffies */ 58 59 /* Control registers */ 60 u8 cregs[0x08]; 61 62 /* Voltage registers */ 63 u8 vregs[0x0d]; 64 65 /* GPIO ADC registers */ 66 bool use_extra_gpios; 67 int gpios[3]; 68}; 69 70/* 71 * Update the readings from the GPIO pins. If the driver has been configured to 72 * sample all GPIO's as analog voltages, a round-robin sampling method is used. 73 * Otherwise, only the configured GPIO pin is sampled. 74 * 75 * LOCKING: must hold data->update_lock 76 */ 77static void ltc4245_update_gpios(struct device *dev) 78{ 79 struct i2c_client *client = to_i2c_client(dev); 80 struct ltc4245_data *data = i2c_get_clientdata(client); 81 u8 gpio_curr, gpio_next, gpio_reg; 82 int i; 83 84 /* no extra gpio support, we're basically done */ 85 if (!data->use_extra_gpios) { 86 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; 87 return; 88 } 89 90 /* 91 * If the last reading was too long ago, then we mark all old GPIO 92 * readings as stale by setting them to -EAGAIN 93 */ 94 if (time_after(jiffies, data->last_updated + 5 * HZ)) { 95 dev_dbg(&client->dev, "Marking GPIOs invalid\n"); 96 for (i = 0; i < ARRAY_SIZE(data->gpios); i++) 97 data->gpios[i] = -EAGAIN; 98 } 99 100 /* 101 * Get the current GPIO pin 102 * 103 * The datasheet calls these GPIO[1-3], but we'll calculate the zero 104 * based array index instead, and call them GPIO[0-2]. This is much 105 * easier to think about. 106 */ 107 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6; 108 if (gpio_curr > 0) 109 gpio_curr -= 1; 110 111 /* Read the GPIO voltage from the GPIOADC register */ 112 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10]; 113 114 /* Find the next GPIO pin to read */ 115 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios); 116 117 /* 118 * Calculate the correct setting for the GPIO register so it will 119 * sample the next GPIO pin 120 */ 121 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6); 122 123 /* Update the GPIO register */ 124 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg); 125 126 /* Update saved data */ 127 data->cregs[LTC4245_GPIO] = gpio_reg; 128} 129 130static struct ltc4245_data *ltc4245_update_device(struct device *dev) 131{ 132 struct i2c_client *client = to_i2c_client(dev); 133 struct ltc4245_data *data = i2c_get_clientdata(client); 134 s32 val; 135 int i; 136 137 mutex_lock(&data->update_lock); 138 139 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { 140 141 dev_dbg(&client->dev, "Starting ltc4245 update\n"); 142 143 /* Read control registers -- 0x00 to 0x07 */ 144 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { 145 val = i2c_smbus_read_byte_data(client, i); 146 if (unlikely(val < 0)) 147 data->cregs[i] = 0; 148 else 149 data->cregs[i] = val; 150 } 151 152 /* Read voltage registers -- 0x10 to 0x1c */ 153 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { 154 val = i2c_smbus_read_byte_data(client, i+0x10); 155 if (unlikely(val < 0)) 156 data->vregs[i] = 0; 157 else 158 data->vregs[i] = val; 159 } 160 161 /* Update GPIO readings */ 162 ltc4245_update_gpios(dev); 163 164 data->last_updated = jiffies; 165 data->valid = 1; 166 } 167 168 mutex_unlock(&data->update_lock); 169 170 return data; 171} 172 173/* Return the voltage from the given register in millivolts */ 174static int ltc4245_get_voltage(struct device *dev, u8 reg) 175{ 176 struct ltc4245_data *data = ltc4245_update_device(dev); 177 const u8 regval = data->vregs[reg - 0x10]; 178 u32 voltage = 0; 179 180 switch (reg) { 181 case LTC4245_12VIN: 182 case LTC4245_12VOUT: 183 voltage = regval * 55; 184 break; 185 case LTC4245_5VIN: 186 case LTC4245_5VOUT: 187 voltage = regval * 22; 188 break; 189 case LTC4245_3VIN: 190 case LTC4245_3VOUT: 191 voltage = regval * 15; 192 break; 193 case LTC4245_VEEIN: 194 case LTC4245_VEEOUT: 195 voltage = regval * -55; 196 break; 197 case LTC4245_GPIOADC: 198 voltage = regval * 10; 199 break; 200 default: 201 /* If we get here, the developer messed up */ 202 WARN_ON_ONCE(1); 203 break; 204 } 205 206 return voltage; 207} 208 209/* Return the current in the given sense register in milliAmperes */ 210static unsigned int ltc4245_get_current(struct device *dev, u8 reg) 211{ 212 struct ltc4245_data *data = ltc4245_update_device(dev); 213 const u8 regval = data->vregs[reg - 0x10]; 214 unsigned int voltage; 215 unsigned int curr; 216 217 /* The strange looking conversions that follow are fixed-point 218 * math, since we cannot do floating point in the kernel. 219 * 220 * Step 1: convert sense register to microVolts 221 * Step 2: convert voltage to milliAmperes 222 * 223 * If you play around with the V=IR equation, you come up with 224 * the following: X uV / Y mOhm == Z mA 225 * 226 * With the resistors that are fractions of a milliOhm, we multiply 227 * the voltage and resistance by 10, to shift the decimal point. 228 * Now we can use the normal division operator again. 229 */ 230 231 switch (reg) { 232 case LTC4245_12VSENSE: 233 voltage = regval * 250; /* voltage in uV */ 234 curr = voltage / 50; /* sense resistor 50 mOhm */ 235 break; 236 case LTC4245_5VSENSE: 237 voltage = regval * 125; /* voltage in uV */ 238 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ 239 break; 240 case LTC4245_3VSENSE: 241 voltage = regval * 125; /* voltage in uV */ 242 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ 243 break; 244 case LTC4245_VEESENSE: 245 voltage = regval * 250; /* voltage in uV */ 246 curr = voltage / 100; /* sense resistor 100 mOhm */ 247 break; 248 default: 249 /* If we get here, the developer messed up */ 250 WARN_ON_ONCE(1); 251 curr = 0; 252 break; 253 } 254 255 return curr; 256} 257 258static ssize_t ltc4245_show_voltage(struct device *dev, 259 struct device_attribute *da, 260 char *buf) 261{ 262 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 263 const int voltage = ltc4245_get_voltage(dev, attr->index); 264 265 return snprintf(buf, PAGE_SIZE, "%d\n", voltage); 266} 267 268static ssize_t ltc4245_show_current(struct device *dev, 269 struct device_attribute *da, 270 char *buf) 271{ 272 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 273 const unsigned int curr = ltc4245_get_current(dev, attr->index); 274 275 return snprintf(buf, PAGE_SIZE, "%u\n", curr); 276} 277 278static ssize_t ltc4245_show_power(struct device *dev, 279 struct device_attribute *da, 280 char *buf) 281{ 282 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 283 const unsigned int curr = ltc4245_get_current(dev, attr->index); 284 const int output_voltage = ltc4245_get_voltage(dev, attr->index+1); 285 286 /* current in mA * voltage in mV == power in uW */ 287 const unsigned int power = abs(output_voltage * curr); 288 289 return snprintf(buf, PAGE_SIZE, "%u\n", power); 290} 291 292static ssize_t ltc4245_show_alarm(struct device *dev, 293 struct device_attribute *da, 294 char *buf) 295{ 296 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da); 297 struct ltc4245_data *data = ltc4245_update_device(dev); 298 const u8 reg = data->cregs[attr->index]; 299 const u32 mask = attr->nr; 300 301 return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0); 302} 303 304static ssize_t ltc4245_show_gpio(struct device *dev, 305 struct device_attribute *da, 306 char *buf) 307{ 308 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 309 struct ltc4245_data *data = ltc4245_update_device(dev); 310 int val = data->gpios[attr->index]; 311 312 /* handle stale GPIO's */ 313 if (val < 0) 314 return val; 315 316 /* Convert to millivolts and print */ 317 return snprintf(buf, PAGE_SIZE, "%u\n", val * 10); 318} 319 320/* These macros are used below in constructing device attribute objects 321 * for use with sysfs_create_group() to make a sysfs device file 322 * for each register. 323 */ 324 325#define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \ 326 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 327 ltc4245_show_voltage, NULL, ltc4245_cmd_idx) 328 329#define LTC4245_CURRENT(name, ltc4245_cmd_idx) \ 330 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 331 ltc4245_show_current, NULL, ltc4245_cmd_idx) 332 333#define LTC4245_POWER(name, ltc4245_cmd_idx) \ 334 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 335 ltc4245_show_power, NULL, ltc4245_cmd_idx) 336 337#define LTC4245_ALARM(name, mask, reg) \ 338 static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \ 339 ltc4245_show_alarm, NULL, (mask), reg) 340 341#define LTC4245_GPIO_VOLTAGE(name, gpio_num) \ 342 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 343 ltc4245_show_gpio, NULL, gpio_num) 344 345/* Construct a sensor_device_attribute structure for each register */ 346 347/* Input voltages */ 348LTC4245_VOLTAGE(in1_input, LTC4245_12VIN); 349LTC4245_VOLTAGE(in2_input, LTC4245_5VIN); 350LTC4245_VOLTAGE(in3_input, LTC4245_3VIN); 351LTC4245_VOLTAGE(in4_input, LTC4245_VEEIN); 352 353/* Input undervoltage alarms */ 354LTC4245_ALARM(in1_min_alarm, (1 << 0), LTC4245_FAULT1); 355LTC4245_ALARM(in2_min_alarm, (1 << 1), LTC4245_FAULT1); 356LTC4245_ALARM(in3_min_alarm, (1 << 2), LTC4245_FAULT1); 357LTC4245_ALARM(in4_min_alarm, (1 << 3), LTC4245_FAULT1); 358 359/* Currents (via sense resistor) */ 360LTC4245_CURRENT(curr1_input, LTC4245_12VSENSE); 361LTC4245_CURRENT(curr2_input, LTC4245_5VSENSE); 362LTC4245_CURRENT(curr3_input, LTC4245_3VSENSE); 363LTC4245_CURRENT(curr4_input, LTC4245_VEESENSE); 364 365/* Overcurrent alarms */ 366LTC4245_ALARM(curr1_max_alarm, (1 << 4), LTC4245_FAULT1); 367LTC4245_ALARM(curr2_max_alarm, (1 << 5), LTC4245_FAULT1); 368LTC4245_ALARM(curr3_max_alarm, (1 << 6), LTC4245_FAULT1); 369LTC4245_ALARM(curr4_max_alarm, (1 << 7), LTC4245_FAULT1); 370 371/* Output voltages */ 372LTC4245_VOLTAGE(in5_input, LTC4245_12VOUT); 373LTC4245_VOLTAGE(in6_input, LTC4245_5VOUT); 374LTC4245_VOLTAGE(in7_input, LTC4245_3VOUT); 375LTC4245_VOLTAGE(in8_input, LTC4245_VEEOUT); 376 377/* Power Bad alarms */ 378LTC4245_ALARM(in5_min_alarm, (1 << 0), LTC4245_FAULT2); 379LTC4245_ALARM(in6_min_alarm, (1 << 1), LTC4245_FAULT2); 380LTC4245_ALARM(in7_min_alarm, (1 << 2), LTC4245_FAULT2); 381LTC4245_ALARM(in8_min_alarm, (1 << 3), LTC4245_FAULT2); 382 383/* GPIO voltages */ 384LTC4245_GPIO_VOLTAGE(in9_input, 0); 385LTC4245_GPIO_VOLTAGE(in10_input, 1); 386LTC4245_GPIO_VOLTAGE(in11_input, 2); 387 388/* Power Consumption (virtual) */ 389LTC4245_POWER(power1_input, LTC4245_12VSENSE); 390LTC4245_POWER(power2_input, LTC4245_5VSENSE); 391LTC4245_POWER(power3_input, LTC4245_3VSENSE); 392LTC4245_POWER(power4_input, LTC4245_VEESENSE); 393 394/* Finally, construct an array of pointers to members of the above objects, 395 * as required for sysfs_create_group() 396 */ 397static struct attribute *ltc4245_std_attributes[] = { 398 &sensor_dev_attr_in1_input.dev_attr.attr, 399 &sensor_dev_attr_in2_input.dev_attr.attr, 400 &sensor_dev_attr_in3_input.dev_attr.attr, 401 &sensor_dev_attr_in4_input.dev_attr.attr, 402 403 &sensor_dev_attr_in1_min_alarm.dev_attr.attr, 404 &sensor_dev_attr_in2_min_alarm.dev_attr.attr, 405 &sensor_dev_attr_in3_min_alarm.dev_attr.attr, 406 &sensor_dev_attr_in4_min_alarm.dev_attr.attr, 407 408 &sensor_dev_attr_curr1_input.dev_attr.attr, 409 &sensor_dev_attr_curr2_input.dev_attr.attr, 410 &sensor_dev_attr_curr3_input.dev_attr.attr, 411 &sensor_dev_attr_curr4_input.dev_attr.attr, 412 413 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, 414 &sensor_dev_attr_curr2_max_alarm.dev_attr.attr, 415 &sensor_dev_attr_curr3_max_alarm.dev_attr.attr, 416 &sensor_dev_attr_curr4_max_alarm.dev_attr.attr, 417 418 &sensor_dev_attr_in5_input.dev_attr.attr, 419 &sensor_dev_attr_in6_input.dev_attr.attr, 420 &sensor_dev_attr_in7_input.dev_attr.attr, 421 &sensor_dev_attr_in8_input.dev_attr.attr, 422 423 &sensor_dev_attr_in5_min_alarm.dev_attr.attr, 424 &sensor_dev_attr_in6_min_alarm.dev_attr.attr, 425 &sensor_dev_attr_in7_min_alarm.dev_attr.attr, 426 &sensor_dev_attr_in8_min_alarm.dev_attr.attr, 427 428 &sensor_dev_attr_in9_input.dev_attr.attr, 429 430 &sensor_dev_attr_power1_input.dev_attr.attr, 431 &sensor_dev_attr_power2_input.dev_attr.attr, 432 &sensor_dev_attr_power3_input.dev_attr.attr, 433 &sensor_dev_attr_power4_input.dev_attr.attr, 434 435 NULL, 436}; 437 438static struct attribute *ltc4245_gpio_attributes[] = { 439 &sensor_dev_attr_in10_input.dev_attr.attr, 440 &sensor_dev_attr_in11_input.dev_attr.attr, 441 NULL, 442}; 443 444static const struct attribute_group ltc4245_std_group = { 445 .attrs = ltc4245_std_attributes, 446}; 447 448static const struct attribute_group ltc4245_gpio_group = { 449 .attrs = ltc4245_gpio_attributes, 450}; 451 452static int ltc4245_sysfs_create_groups(struct i2c_client *client) 453{ 454 struct ltc4245_data *data = i2c_get_clientdata(client); 455 struct device *dev = &client->dev; 456 int ret; 457 458 /* register the standard sysfs attributes */ 459 ret = sysfs_create_group(&dev->kobj, <c4245_std_group); 460 if (ret) { 461 dev_err(dev, "unable to register standard attributes\n"); 462 return ret; 463 } 464 465 /* if we're using the extra gpio support, register it's attributes */ 466 if (data->use_extra_gpios) { 467 ret = sysfs_create_group(&dev->kobj, <c4245_gpio_group); 468 if (ret) { 469 dev_err(dev, "unable to register gpio attributes\n"); 470 sysfs_remove_group(&dev->kobj, <c4245_std_group); 471 return ret; 472 } 473 } 474 475 return 0; 476} 477 478static void ltc4245_sysfs_remove_groups(struct i2c_client *client) 479{ 480 struct ltc4245_data *data = i2c_get_clientdata(client); 481 struct device *dev = &client->dev; 482 483 if (data->use_extra_gpios) 484 sysfs_remove_group(&dev->kobj, <c4245_gpio_group); 485 486 sysfs_remove_group(&dev->kobj, <c4245_std_group); 487} 488 489static bool ltc4245_use_extra_gpios(struct i2c_client *client) 490{ 491 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 492#ifdef CONFIG_OF 493 struct device_node *np = client->dev.of_node; 494#endif 495 496 /* prefer platform data */ 497 if (pdata) 498 return pdata->use_extra_gpios; 499 500#ifdef CONFIG_OF 501 /* fallback on OF */ 502 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL)) 503 return true; 504#endif 505 506 return false; 507} 508 509static int ltc4245_probe(struct i2c_client *client, 510 const struct i2c_device_id *id) 511{ 512 struct i2c_adapter *adapter = client->adapter; 513 struct ltc4245_data *data; 514 int ret; 515 516 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 517 return -ENODEV; 518 519 data = kzalloc(sizeof(*data), GFP_KERNEL); 520 if (!data) { 521 ret = -ENOMEM; 522 goto out_kzalloc; 523 } 524 525 i2c_set_clientdata(client, data); 526 mutex_init(&data->update_lock); 527 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 528 529 /* Initialize the LTC4245 chip */ 530 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 531 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 532 533 /* Register sysfs hooks */ 534 ret = ltc4245_sysfs_create_groups(client); 535 if (ret) 536 goto out_sysfs_create_groups; 537 538 data->hwmon_dev = hwmon_device_register(&client->dev); 539 if (IS_ERR(data->hwmon_dev)) { 540 ret = PTR_ERR(data->hwmon_dev); 541 goto out_hwmon_device_register; 542 } 543 544 return 0; 545 546out_hwmon_device_register: 547 ltc4245_sysfs_remove_groups(client); 548out_sysfs_create_groups: 549 kfree(data); 550out_kzalloc: 551 return ret; 552} 553 554static int ltc4245_remove(struct i2c_client *client) 555{ 556 struct ltc4245_data *data = i2c_get_clientdata(client); 557 558 hwmon_device_unregister(data->hwmon_dev); 559 ltc4245_sysfs_remove_groups(client); 560 kfree(data); 561 562 return 0; 563} 564 565static const struct i2c_device_id ltc4245_id[] = { 566 { "ltc4245", 0 }, 567 { } 568}; 569MODULE_DEVICE_TABLE(i2c, ltc4245_id); 570 571/* This is the driver that will be inserted */ 572static struct i2c_driver ltc4245_driver = { 573 .driver = { 574 .name = "ltc4245", 575 }, 576 .probe = ltc4245_probe, 577 .remove = ltc4245_remove, 578 .id_table = ltc4245_id, 579}; 580 581static int __init ltc4245_init(void) 582{ 583 return i2c_add_driver(<c4245_driver); 584} 585 586static void __exit ltc4245_exit(void) 587{ 588 i2c_del_driver(<c4245_driver); 589} 590 591MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 592MODULE_DESCRIPTION("LTC4245 driver"); 593MODULE_LICENSE("GPL"); 594 595module_init(ltc4245_init); 596module_exit(ltc4245_exit); 597