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) */ 27 enum 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 52 struct 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 */ 77 static 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 } 129 130 static 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 */ 174 static 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 */ 210 static 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 /* 218 * The strange looking conversions that follow are fixed-point 219 * math, since we cannot do floating point in the kernel. 220 * 221 * Step 1: convert sense register to microVolts 222 * Step 2: convert voltage to milliAmperes 223 * 224 * If you play around with the V=IR equation, you come up with 225 * the following: X uV / Y mOhm == Z mA 226 * 227 * With the resistors that are fractions of a milliOhm, we multiply 228 * the voltage and resistance by 10, to shift the decimal point. 229 * Now we can use the normal division operator again. 230 */ 231 232 switch (reg) { 233 case LTC4245_12VSENSE: 234 voltage = regval * 250; /* voltage in uV */ 235 curr = voltage / 50; /* sense resistor 50 mOhm */ 236 break; 237 case LTC4245_5VSENSE: 238 voltage = regval * 125; /* voltage in uV */ 239 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ 240 break; 241 case LTC4245_3VSENSE: 242 voltage = regval * 125; /* voltage in uV */ 243 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ 244 break; 245 case LTC4245_VEESENSE: 246 voltage = regval * 250; /* voltage in uV */ 247 curr = voltage / 100; /* sense resistor 100 mOhm */ 248 break; 249 default: 250 /* If we get here, the developer messed up */ 251 WARN_ON_ONCE(1); 252 curr = 0; 253 break; 254 } 255 256 return curr; 257 } 258 259 static ssize_t ltc4245_show_voltage(struct device *dev, 260 struct device_attribute *da, 261 char *buf) 262 { 263 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 264 const int voltage = ltc4245_get_voltage(dev, attr->index); 265 266 return snprintf(buf, PAGE_SIZE, "%d\n", voltage); 267 } 268 269 static ssize_t ltc4245_show_current(struct device *dev, 270 struct device_attribute *da, 271 char *buf) 272 { 273 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 274 const unsigned int curr = ltc4245_get_current(dev, attr->index); 275 276 return snprintf(buf, PAGE_SIZE, "%u\n", curr); 277 } 278 279 static ssize_t ltc4245_show_power(struct device *dev, 280 struct device_attribute *da, 281 char *buf) 282 { 283 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 284 const unsigned int curr = ltc4245_get_current(dev, attr->index); 285 const int output_voltage = ltc4245_get_voltage(dev, attr->index+1); 286 287 /* current in mA * voltage in mV == power in uW */ 288 const unsigned int power = abs(output_voltage * curr); 289 290 return snprintf(buf, PAGE_SIZE, "%u\n", power); 291 } 292 293 static ssize_t ltc4245_show_alarm(struct device *dev, 294 struct device_attribute *da, 295 char *buf) 296 { 297 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da); 298 struct ltc4245_data *data = ltc4245_update_device(dev); 299 const u8 reg = data->cregs[attr->index]; 300 const u32 mask = attr->nr; 301 302 return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0); 303 } 304 305 static ssize_t ltc4245_show_gpio(struct device *dev, 306 struct device_attribute *da, 307 char *buf) 308 { 309 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 310 struct ltc4245_data *data = ltc4245_update_device(dev); 311 int val = data->gpios[attr->index]; 312 313 /* handle stale GPIO's */ 314 if (val < 0) 315 return val; 316 317 /* Convert to millivolts and print */ 318 return snprintf(buf, PAGE_SIZE, "%u\n", val * 10); 319 } 320 321 /* 322 * These macros are used below in constructing device attribute objects 323 * for use with sysfs_create_group() to make a sysfs device file 324 * for each register. 325 */ 326 327 #define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \ 328 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 329 ltc4245_show_voltage, NULL, ltc4245_cmd_idx) 330 331 #define LTC4245_CURRENT(name, ltc4245_cmd_idx) \ 332 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 333 ltc4245_show_current, NULL, ltc4245_cmd_idx) 334 335 #define LTC4245_POWER(name, ltc4245_cmd_idx) \ 336 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 337 ltc4245_show_power, NULL, ltc4245_cmd_idx) 338 339 #define LTC4245_ALARM(name, mask, reg) \ 340 static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \ 341 ltc4245_show_alarm, NULL, (mask), reg) 342 343 #define LTC4245_GPIO_VOLTAGE(name, gpio_num) \ 344 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 345 ltc4245_show_gpio, NULL, gpio_num) 346 347 /* Construct a sensor_device_attribute structure for each register */ 348 349 /* Input voltages */ 350 LTC4245_VOLTAGE(in1_input, LTC4245_12VIN); 351 LTC4245_VOLTAGE(in2_input, LTC4245_5VIN); 352 LTC4245_VOLTAGE(in3_input, LTC4245_3VIN); 353 LTC4245_VOLTAGE(in4_input, LTC4245_VEEIN); 354 355 /* Input undervoltage alarms */ 356 LTC4245_ALARM(in1_min_alarm, (1 << 0), LTC4245_FAULT1); 357 LTC4245_ALARM(in2_min_alarm, (1 << 1), LTC4245_FAULT1); 358 LTC4245_ALARM(in3_min_alarm, (1 << 2), LTC4245_FAULT1); 359 LTC4245_ALARM(in4_min_alarm, (1 << 3), LTC4245_FAULT1); 360 361 /* Currents (via sense resistor) */ 362 LTC4245_CURRENT(curr1_input, LTC4245_12VSENSE); 363 LTC4245_CURRENT(curr2_input, LTC4245_5VSENSE); 364 LTC4245_CURRENT(curr3_input, LTC4245_3VSENSE); 365 LTC4245_CURRENT(curr4_input, LTC4245_VEESENSE); 366 367 /* Overcurrent alarms */ 368 LTC4245_ALARM(curr1_max_alarm, (1 << 4), LTC4245_FAULT1); 369 LTC4245_ALARM(curr2_max_alarm, (1 << 5), LTC4245_FAULT1); 370 LTC4245_ALARM(curr3_max_alarm, (1 << 6), LTC4245_FAULT1); 371 LTC4245_ALARM(curr4_max_alarm, (1 << 7), LTC4245_FAULT1); 372 373 /* Output voltages */ 374 LTC4245_VOLTAGE(in5_input, LTC4245_12VOUT); 375 LTC4245_VOLTAGE(in6_input, LTC4245_5VOUT); 376 LTC4245_VOLTAGE(in7_input, LTC4245_3VOUT); 377 LTC4245_VOLTAGE(in8_input, LTC4245_VEEOUT); 378 379 /* Power Bad alarms */ 380 LTC4245_ALARM(in5_min_alarm, (1 << 0), LTC4245_FAULT2); 381 LTC4245_ALARM(in6_min_alarm, (1 << 1), LTC4245_FAULT2); 382 LTC4245_ALARM(in7_min_alarm, (1 << 2), LTC4245_FAULT2); 383 LTC4245_ALARM(in8_min_alarm, (1 << 3), LTC4245_FAULT2); 384 385 /* GPIO voltages */ 386 LTC4245_GPIO_VOLTAGE(in9_input, 0); 387 LTC4245_GPIO_VOLTAGE(in10_input, 1); 388 LTC4245_GPIO_VOLTAGE(in11_input, 2); 389 390 /* Power Consumption (virtual) */ 391 LTC4245_POWER(power1_input, LTC4245_12VSENSE); 392 LTC4245_POWER(power2_input, LTC4245_5VSENSE); 393 LTC4245_POWER(power3_input, LTC4245_3VSENSE); 394 LTC4245_POWER(power4_input, LTC4245_VEESENSE); 395 396 /* 397 * Finally, construct an array of pointers to members of the above objects, 398 * as required for sysfs_create_group() 399 */ 400 static struct attribute *ltc4245_std_attributes[] = { 401 &sensor_dev_attr_in1_input.dev_attr.attr, 402 &sensor_dev_attr_in2_input.dev_attr.attr, 403 &sensor_dev_attr_in3_input.dev_attr.attr, 404 &sensor_dev_attr_in4_input.dev_attr.attr, 405 406 &sensor_dev_attr_in1_min_alarm.dev_attr.attr, 407 &sensor_dev_attr_in2_min_alarm.dev_attr.attr, 408 &sensor_dev_attr_in3_min_alarm.dev_attr.attr, 409 &sensor_dev_attr_in4_min_alarm.dev_attr.attr, 410 411 &sensor_dev_attr_curr1_input.dev_attr.attr, 412 &sensor_dev_attr_curr2_input.dev_attr.attr, 413 &sensor_dev_attr_curr3_input.dev_attr.attr, 414 &sensor_dev_attr_curr4_input.dev_attr.attr, 415 416 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, 417 &sensor_dev_attr_curr2_max_alarm.dev_attr.attr, 418 &sensor_dev_attr_curr3_max_alarm.dev_attr.attr, 419 &sensor_dev_attr_curr4_max_alarm.dev_attr.attr, 420 421 &sensor_dev_attr_in5_input.dev_attr.attr, 422 &sensor_dev_attr_in6_input.dev_attr.attr, 423 &sensor_dev_attr_in7_input.dev_attr.attr, 424 &sensor_dev_attr_in8_input.dev_attr.attr, 425 426 &sensor_dev_attr_in5_min_alarm.dev_attr.attr, 427 &sensor_dev_attr_in6_min_alarm.dev_attr.attr, 428 &sensor_dev_attr_in7_min_alarm.dev_attr.attr, 429 &sensor_dev_attr_in8_min_alarm.dev_attr.attr, 430 431 &sensor_dev_attr_in9_input.dev_attr.attr, 432 433 &sensor_dev_attr_power1_input.dev_attr.attr, 434 &sensor_dev_attr_power2_input.dev_attr.attr, 435 &sensor_dev_attr_power3_input.dev_attr.attr, 436 &sensor_dev_attr_power4_input.dev_attr.attr, 437 438 NULL, 439 }; 440 441 static struct attribute *ltc4245_gpio_attributes[] = { 442 &sensor_dev_attr_in10_input.dev_attr.attr, 443 &sensor_dev_attr_in11_input.dev_attr.attr, 444 NULL, 445 }; 446 447 static const struct attribute_group ltc4245_std_group = { 448 .attrs = ltc4245_std_attributes, 449 }; 450 451 static const struct attribute_group ltc4245_gpio_group = { 452 .attrs = ltc4245_gpio_attributes, 453 }; 454 455 static int ltc4245_sysfs_create_groups(struct i2c_client *client) 456 { 457 struct ltc4245_data *data = i2c_get_clientdata(client); 458 struct device *dev = &client->dev; 459 int ret; 460 461 /* register the standard sysfs attributes */ 462 ret = sysfs_create_group(&dev->kobj, <c4245_std_group); 463 if (ret) { 464 dev_err(dev, "unable to register standard attributes\n"); 465 return ret; 466 } 467 468 /* if we're using the extra gpio support, register it's attributes */ 469 if (data->use_extra_gpios) { 470 ret = sysfs_create_group(&dev->kobj, <c4245_gpio_group); 471 if (ret) { 472 dev_err(dev, "unable to register gpio attributes\n"); 473 sysfs_remove_group(&dev->kobj, <c4245_std_group); 474 return ret; 475 } 476 } 477 478 return 0; 479 } 480 481 static void ltc4245_sysfs_remove_groups(struct i2c_client *client) 482 { 483 struct ltc4245_data *data = i2c_get_clientdata(client); 484 struct device *dev = &client->dev; 485 486 if (data->use_extra_gpios) 487 sysfs_remove_group(&dev->kobj, <c4245_gpio_group); 488 489 sysfs_remove_group(&dev->kobj, <c4245_std_group); 490 } 491 492 static bool ltc4245_use_extra_gpios(struct i2c_client *client) 493 { 494 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 495 #ifdef CONFIG_OF 496 struct device_node *np = client->dev.of_node; 497 #endif 498 499 /* prefer platform data */ 500 if (pdata) 501 return pdata->use_extra_gpios; 502 503 #ifdef CONFIG_OF 504 /* fallback on OF */ 505 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL)) 506 return true; 507 #endif 508 509 return false; 510 } 511 512 static int ltc4245_probe(struct i2c_client *client, 513 const struct i2c_device_id *id) 514 { 515 struct i2c_adapter *adapter = client->adapter; 516 struct ltc4245_data *data; 517 int ret; 518 519 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 520 return -ENODEV; 521 522 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 523 if (!data) 524 return -ENOMEM; 525 526 i2c_set_clientdata(client, data); 527 mutex_init(&data->update_lock); 528 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 529 530 /* Initialize the LTC4245 chip */ 531 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 532 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 533 534 /* Register sysfs hooks */ 535 ret = ltc4245_sysfs_create_groups(client); 536 if (ret) 537 return ret; 538 539 data->hwmon_dev = hwmon_device_register(&client->dev); 540 if (IS_ERR(data->hwmon_dev)) { 541 ret = PTR_ERR(data->hwmon_dev); 542 goto out_hwmon_device_register; 543 } 544 545 return 0; 546 547 out_hwmon_device_register: 548 ltc4245_sysfs_remove_groups(client); 549 return ret; 550 } 551 552 static int ltc4245_remove(struct i2c_client *client) 553 { 554 struct ltc4245_data *data = i2c_get_clientdata(client); 555 556 hwmon_device_unregister(data->hwmon_dev); 557 ltc4245_sysfs_remove_groups(client); 558 559 return 0; 560 } 561 562 static const struct i2c_device_id ltc4245_id[] = { 563 { "ltc4245", 0 }, 564 { } 565 }; 566 MODULE_DEVICE_TABLE(i2c, ltc4245_id); 567 568 /* This is the driver that will be inserted */ 569 static struct i2c_driver ltc4245_driver = { 570 .driver = { 571 .name = "ltc4245", 572 }, 573 .probe = ltc4245_probe, 574 .remove = ltc4245_remove, 575 .id_table = ltc4245_id, 576 }; 577 578 module_i2c_driver(ltc4245_driver); 579 580 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 581 MODULE_DESCRIPTION("LTC4245 driver"); 582 MODULE_LICENSE("GPL"); 583