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/bitops.h> 20 #include <linux/err.h> 21 #include <linux/slab.h> 22 #include <linux/i2c.h> 23 #include <linux/hwmon.h> 24 #include <linux/hwmon-sysfs.h> 25 #include <linux/jiffies.h> 26 #include <linux/i2c/ltc4245.h> 27 28 /* Here are names of the chip's registers (a.k.a. commands) */ 29 enum ltc4245_cmd { 30 LTC4245_STATUS = 0x00, /* readonly */ 31 LTC4245_ALERT = 0x01, 32 LTC4245_CONTROL = 0x02, 33 LTC4245_ON = 0x03, 34 LTC4245_FAULT1 = 0x04, 35 LTC4245_FAULT2 = 0x05, 36 LTC4245_GPIO = 0x06, 37 LTC4245_ADCADR = 0x07, 38 39 LTC4245_12VIN = 0x10, 40 LTC4245_12VSENSE = 0x11, 41 LTC4245_12VOUT = 0x12, 42 LTC4245_5VIN = 0x13, 43 LTC4245_5VSENSE = 0x14, 44 LTC4245_5VOUT = 0x15, 45 LTC4245_3VIN = 0x16, 46 LTC4245_3VSENSE = 0x17, 47 LTC4245_3VOUT = 0x18, 48 LTC4245_VEEIN = 0x19, 49 LTC4245_VEESENSE = 0x1a, 50 LTC4245_VEEOUT = 0x1b, 51 LTC4245_GPIOADC = 0x1c, 52 }; 53 54 struct ltc4245_data { 55 struct i2c_client *client; 56 57 struct mutex update_lock; 58 bool valid; 59 unsigned long last_updated; /* in jiffies */ 60 61 /* Control registers */ 62 u8 cregs[0x08]; 63 64 /* Voltage registers */ 65 u8 vregs[0x0d]; 66 67 /* GPIO ADC registers */ 68 bool use_extra_gpios; 69 int gpios[3]; 70 }; 71 72 /* 73 * Update the readings from the GPIO pins. If the driver has been configured to 74 * sample all GPIO's as analog voltages, a round-robin sampling method is used. 75 * Otherwise, only the configured GPIO pin is sampled. 76 * 77 * LOCKING: must hold data->update_lock 78 */ 79 static void ltc4245_update_gpios(struct device *dev) 80 { 81 struct ltc4245_data *data = dev_get_drvdata(dev); 82 struct i2c_client *client = data->client; 83 u8 gpio_curr, gpio_next, gpio_reg; 84 int i; 85 86 /* no extra gpio support, we're basically done */ 87 if (!data->use_extra_gpios) { 88 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; 89 return; 90 } 91 92 /* 93 * If the last reading was too long ago, then we mark all old GPIO 94 * readings as stale by setting them to -EAGAIN 95 */ 96 if (time_after(jiffies, data->last_updated + 5 * HZ)) { 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 ltc4245_data *data = dev_get_drvdata(dev); 134 struct i2c_client *client = data->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 /* Read control registers -- 0x00 to 0x07 */ 143 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { 144 val = i2c_smbus_read_byte_data(client, i); 145 if (unlikely(val < 0)) 146 data->cregs[i] = 0; 147 else 148 data->cregs[i] = val; 149 } 150 151 /* Read voltage registers -- 0x10 to 0x1c */ 152 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { 153 val = i2c_smbus_read_byte_data(client, i+0x10); 154 if (unlikely(val < 0)) 155 data->vregs[i] = 0; 156 else 157 data->vregs[i] = val; 158 } 159 160 /* Update GPIO readings */ 161 ltc4245_update_gpios(dev); 162 163 data->last_updated = jiffies; 164 data->valid = true; 165 } 166 167 mutex_unlock(&data->update_lock); 168 169 return data; 170 } 171 172 /* Return the voltage from the given register in millivolts */ 173 static int ltc4245_get_voltage(struct device *dev, u8 reg) 174 { 175 struct ltc4245_data *data = ltc4245_update_device(dev); 176 const u8 regval = data->vregs[reg - 0x10]; 177 u32 voltage = 0; 178 179 switch (reg) { 180 case LTC4245_12VIN: 181 case LTC4245_12VOUT: 182 voltage = regval * 55; 183 break; 184 case LTC4245_5VIN: 185 case LTC4245_5VOUT: 186 voltage = regval * 22; 187 break; 188 case LTC4245_3VIN: 189 case LTC4245_3VOUT: 190 voltage = regval * 15; 191 break; 192 case LTC4245_VEEIN: 193 case LTC4245_VEEOUT: 194 voltage = regval * -55; 195 break; 196 case LTC4245_GPIOADC: 197 voltage = regval * 10; 198 break; 199 default: 200 /* If we get here, the developer messed up */ 201 WARN_ON_ONCE(1); 202 break; 203 } 204 205 return voltage; 206 } 207 208 /* Return the current in the given sense register in milliAmperes */ 209 static unsigned int ltc4245_get_current(struct device *dev, u8 reg) 210 { 211 struct ltc4245_data *data = ltc4245_update_device(dev); 212 const u8 regval = data->vregs[reg - 0x10]; 213 unsigned int voltage; 214 unsigned int curr; 215 216 /* 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 } 257 258 /* Map from voltage channel index to voltage register */ 259 260 static const s8 ltc4245_in_regs[] = { 261 LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN, 262 LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT, 263 }; 264 265 /* Map from current channel index to current register */ 266 267 static const s8 ltc4245_curr_regs[] = { 268 LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE, 269 }; 270 271 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel, 272 long *val) 273 { 274 struct ltc4245_data *data = ltc4245_update_device(dev); 275 276 switch (attr) { 277 case hwmon_curr_input: 278 *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 279 return 0; 280 case hwmon_curr_max_alarm: 281 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4)); 282 return 0; 283 default: 284 return -EOPNOTSUPP; 285 } 286 } 287 288 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val) 289 { 290 struct ltc4245_data *data = ltc4245_update_device(dev); 291 292 switch (attr) { 293 case hwmon_in_input: 294 if (channel < 8) { 295 *val = ltc4245_get_voltage(dev, 296 ltc4245_in_regs[channel]); 297 } else { 298 int regval = data->gpios[channel - 8]; 299 300 if (regval < 0) 301 return regval; 302 *val = regval * 10; 303 } 304 return 0; 305 case hwmon_in_min_alarm: 306 if (channel < 4) 307 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel)); 308 else 309 *val = !!(data->cregs[LTC4245_FAULT2] & 310 BIT(channel - 4)); 311 return 0; 312 default: 313 return -EOPNOTSUPP; 314 } 315 } 316 317 static int ltc4245_read_power(struct device *dev, u32 attr, int channel, 318 long *val) 319 { 320 unsigned long curr; 321 long voltage; 322 323 switch (attr) { 324 case hwmon_power_input: 325 (void)ltc4245_update_device(dev); 326 curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 327 voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]); 328 *val = abs(curr * voltage); 329 return 0; 330 default: 331 return -EOPNOTSUPP; 332 } 333 } 334 335 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type, 336 u32 attr, int channel, long *val) 337 { 338 339 switch (type) { 340 case hwmon_curr: 341 return ltc4245_read_curr(dev, attr, channel, val); 342 case hwmon_power: 343 return ltc4245_read_power(dev, attr, channel, val); 344 case hwmon_in: 345 return ltc4245_read_in(dev, attr, channel - 1, val); 346 default: 347 return -EOPNOTSUPP; 348 } 349 } 350 351 static umode_t ltc4245_is_visible(const void *_data, 352 enum hwmon_sensor_types type, 353 u32 attr, int channel) 354 { 355 const struct ltc4245_data *data = _data; 356 357 switch (type) { 358 case hwmon_in: 359 if (channel == 0) 360 return 0; 361 switch (attr) { 362 case hwmon_in_input: 363 if (channel > 9 && !data->use_extra_gpios) 364 return 0; 365 return S_IRUGO; 366 case hwmon_in_min_alarm: 367 if (channel > 8) 368 return 0; 369 return S_IRUGO; 370 default: 371 return 0; 372 } 373 case hwmon_curr: 374 switch (attr) { 375 case hwmon_curr_input: 376 case hwmon_curr_max_alarm: 377 return S_IRUGO; 378 default: 379 return 0; 380 } 381 case hwmon_power: 382 switch (attr) { 383 case hwmon_power_input: 384 return S_IRUGO; 385 default: 386 return 0; 387 } 388 default: 389 return 0; 390 } 391 } 392 393 static const u32 ltc4245_in_config[] = { 394 HWMON_I_INPUT, /* dummy, skipped in is_visible */ 395 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 396 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 397 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 398 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 399 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 400 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 401 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 402 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 403 HWMON_I_INPUT, 404 HWMON_I_INPUT, 405 HWMON_I_INPUT, 406 0 407 }; 408 409 static const struct hwmon_channel_info ltc4245_in = { 410 .type = hwmon_in, 411 .config = ltc4245_in_config, 412 }; 413 414 static const u32 ltc4245_curr_config[] = { 415 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 416 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 417 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 418 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 419 0 420 }; 421 422 static const struct hwmon_channel_info ltc4245_curr = { 423 .type = hwmon_curr, 424 .config = ltc4245_curr_config, 425 }; 426 427 static const u32 ltc4245_power_config[] = { 428 HWMON_P_INPUT, 429 HWMON_P_INPUT, 430 HWMON_P_INPUT, 431 HWMON_P_INPUT, 432 0 433 }; 434 435 static const struct hwmon_channel_info ltc4245_power = { 436 .type = hwmon_power, 437 .config = ltc4245_power_config, 438 }; 439 440 static const struct hwmon_channel_info *ltc4245_info[] = { 441 <c4245_in, 442 <c4245_curr, 443 <c4245_power, 444 NULL 445 }; 446 447 static const struct hwmon_ops ltc4245_hwmon_ops = { 448 .is_visible = ltc4245_is_visible, 449 .read = ltc4245_read, 450 }; 451 452 static const struct hwmon_chip_info ltc4245_chip_info = { 453 .ops = <c4245_hwmon_ops, 454 .info = ltc4245_info, 455 }; 456 457 static bool ltc4245_use_extra_gpios(struct i2c_client *client) 458 { 459 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 460 struct device_node *np = client->dev.of_node; 461 462 /* prefer platform data */ 463 if (pdata) 464 return pdata->use_extra_gpios; 465 466 /* fallback on OF */ 467 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL)) 468 return true; 469 470 return false; 471 } 472 473 static int ltc4245_probe(struct i2c_client *client, 474 const struct i2c_device_id *id) 475 { 476 struct i2c_adapter *adapter = client->adapter; 477 struct ltc4245_data *data; 478 struct device *hwmon_dev; 479 480 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 481 return -ENODEV; 482 483 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 484 if (!data) 485 return -ENOMEM; 486 487 data->client = client; 488 mutex_init(&data->update_lock); 489 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 490 491 /* Initialize the LTC4245 chip */ 492 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 493 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 494 495 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, 496 client->name, data, 497 <c4245_chip_info, 498 NULL); 499 return PTR_ERR_OR_ZERO(hwmon_dev); 500 } 501 502 static const struct i2c_device_id ltc4245_id[] = { 503 { "ltc4245", 0 }, 504 { } 505 }; 506 MODULE_DEVICE_TABLE(i2c, ltc4245_id); 507 508 /* This is the driver that will be inserted */ 509 static struct i2c_driver ltc4245_driver = { 510 .driver = { 511 .name = "ltc4245", 512 }, 513 .probe = ltc4245_probe, 514 .id_table = ltc4245_id, 515 }; 516 517 module_i2c_driver(ltc4245_driver); 518 519 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 520 MODULE_DESCRIPTION("LTC4245 driver"); 521 MODULE_LICENSE("GPL"); 522