1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller 4 * 5 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu> 6 * 7 * This driver is based on the ds1621 and ina209 drivers. 8 * 9 * Datasheet: 10 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 11 */ 12 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/init.h> 16 #include <linux/bitops.h> 17 #include <linux/err.h> 18 #include <linux/slab.h> 19 #include <linux/i2c.h> 20 #include <linux/hwmon.h> 21 #include <linux/hwmon-sysfs.h> 22 #include <linux/jiffies.h> 23 #include <linux/platform_data/ltc4245.h> 24 25 /* Here are names of the chip's registers (a.k.a. commands) */ 26 enum ltc4245_cmd { 27 LTC4245_STATUS = 0x00, /* readonly */ 28 LTC4245_ALERT = 0x01, 29 LTC4245_CONTROL = 0x02, 30 LTC4245_ON = 0x03, 31 LTC4245_FAULT1 = 0x04, 32 LTC4245_FAULT2 = 0x05, 33 LTC4245_GPIO = 0x06, 34 LTC4245_ADCADR = 0x07, 35 36 LTC4245_12VIN = 0x10, 37 LTC4245_12VSENSE = 0x11, 38 LTC4245_12VOUT = 0x12, 39 LTC4245_5VIN = 0x13, 40 LTC4245_5VSENSE = 0x14, 41 LTC4245_5VOUT = 0x15, 42 LTC4245_3VIN = 0x16, 43 LTC4245_3VSENSE = 0x17, 44 LTC4245_3VOUT = 0x18, 45 LTC4245_VEEIN = 0x19, 46 LTC4245_VEESENSE = 0x1a, 47 LTC4245_VEEOUT = 0x1b, 48 LTC4245_GPIOADC = 0x1c, 49 }; 50 51 struct ltc4245_data { 52 struct i2c_client *client; 53 54 struct mutex update_lock; 55 bool valid; 56 unsigned long last_updated; /* in jiffies */ 57 58 /* Control registers */ 59 u8 cregs[0x08]; 60 61 /* Voltage registers */ 62 u8 vregs[0x0d]; 63 64 /* GPIO ADC registers */ 65 bool use_extra_gpios; 66 int gpios[3]; 67 }; 68 69 /* 70 * Update the readings from the GPIO pins. If the driver has been configured to 71 * sample all GPIO's as analog voltages, a round-robin sampling method is used. 72 * Otherwise, only the configured GPIO pin is sampled. 73 * 74 * LOCKING: must hold data->update_lock 75 */ 76 static void ltc4245_update_gpios(struct device *dev) 77 { 78 struct ltc4245_data *data = dev_get_drvdata(dev); 79 struct i2c_client *client = data->client; 80 u8 gpio_curr, gpio_next, gpio_reg; 81 int i; 82 83 /* no extra gpio support, we're basically done */ 84 if (!data->use_extra_gpios) { 85 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; 86 return; 87 } 88 89 /* 90 * If the last reading was too long ago, then we mark all old GPIO 91 * readings as stale by setting them to -EAGAIN 92 */ 93 if (time_after(jiffies, data->last_updated + 5 * HZ)) { 94 for (i = 0; i < ARRAY_SIZE(data->gpios); i++) 95 data->gpios[i] = -EAGAIN; 96 } 97 98 /* 99 * Get the current GPIO pin 100 * 101 * The datasheet calls these GPIO[1-3], but we'll calculate the zero 102 * based array index instead, and call them GPIO[0-2]. This is much 103 * easier to think about. 104 */ 105 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6; 106 if (gpio_curr > 0) 107 gpio_curr -= 1; 108 109 /* Read the GPIO voltage from the GPIOADC register */ 110 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10]; 111 112 /* Find the next GPIO pin to read */ 113 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios); 114 115 /* 116 * Calculate the correct setting for the GPIO register so it will 117 * sample the next GPIO pin 118 */ 119 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6); 120 121 /* Update the GPIO register */ 122 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg); 123 124 /* Update saved data */ 125 data->cregs[LTC4245_GPIO] = gpio_reg; 126 } 127 128 static struct ltc4245_data *ltc4245_update_device(struct device *dev) 129 { 130 struct ltc4245_data *data = dev_get_drvdata(dev); 131 struct i2c_client *client = data->client; 132 s32 val; 133 int i; 134 135 mutex_lock(&data->update_lock); 136 137 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { 138 139 /* Read control registers -- 0x00 to 0x07 */ 140 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { 141 val = i2c_smbus_read_byte_data(client, i); 142 if (unlikely(val < 0)) 143 data->cregs[i] = 0; 144 else 145 data->cregs[i] = val; 146 } 147 148 /* Read voltage registers -- 0x10 to 0x1c */ 149 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { 150 val = i2c_smbus_read_byte_data(client, i+0x10); 151 if (unlikely(val < 0)) 152 data->vregs[i] = 0; 153 else 154 data->vregs[i] = val; 155 } 156 157 /* Update GPIO readings */ 158 ltc4245_update_gpios(dev); 159 160 data->last_updated = jiffies; 161 data->valid = true; 162 } 163 164 mutex_unlock(&data->update_lock); 165 166 return data; 167 } 168 169 /* Return the voltage from the given register in millivolts */ 170 static int ltc4245_get_voltage(struct device *dev, u8 reg) 171 { 172 struct ltc4245_data *data = ltc4245_update_device(dev); 173 const u8 regval = data->vregs[reg - 0x10]; 174 u32 voltage = 0; 175 176 switch (reg) { 177 case LTC4245_12VIN: 178 case LTC4245_12VOUT: 179 voltage = regval * 55; 180 break; 181 case LTC4245_5VIN: 182 case LTC4245_5VOUT: 183 voltage = regval * 22; 184 break; 185 case LTC4245_3VIN: 186 case LTC4245_3VOUT: 187 voltage = regval * 15; 188 break; 189 case LTC4245_VEEIN: 190 case LTC4245_VEEOUT: 191 voltage = regval * -55; 192 break; 193 case LTC4245_GPIOADC: 194 voltage = regval * 10; 195 break; 196 default: 197 /* If we get here, the developer messed up */ 198 WARN_ON_ONCE(1); 199 break; 200 } 201 202 return voltage; 203 } 204 205 /* Return the current in the given sense register in milliAmperes */ 206 static unsigned int ltc4245_get_current(struct device *dev, u8 reg) 207 { 208 struct ltc4245_data *data = ltc4245_update_device(dev); 209 const u8 regval = data->vregs[reg - 0x10]; 210 unsigned int voltage; 211 unsigned int curr; 212 213 /* 214 * The strange looking conversions that follow are fixed-point 215 * math, since we cannot do floating point in the kernel. 216 * 217 * Step 1: convert sense register to microVolts 218 * Step 2: convert voltage to milliAmperes 219 * 220 * If you play around with the V=IR equation, you come up with 221 * the following: X uV / Y mOhm == Z mA 222 * 223 * With the resistors that are fractions of a milliOhm, we multiply 224 * the voltage and resistance by 10, to shift the decimal point. 225 * Now we can use the normal division operator again. 226 */ 227 228 switch (reg) { 229 case LTC4245_12VSENSE: 230 voltage = regval * 250; /* voltage in uV */ 231 curr = voltage / 50; /* sense resistor 50 mOhm */ 232 break; 233 case LTC4245_5VSENSE: 234 voltage = regval * 125; /* voltage in uV */ 235 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ 236 break; 237 case LTC4245_3VSENSE: 238 voltage = regval * 125; /* voltage in uV */ 239 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ 240 break; 241 case LTC4245_VEESENSE: 242 voltage = regval * 250; /* voltage in uV */ 243 curr = voltage / 100; /* sense resistor 100 mOhm */ 244 break; 245 default: 246 /* If we get here, the developer messed up */ 247 WARN_ON_ONCE(1); 248 curr = 0; 249 break; 250 } 251 252 return curr; 253 } 254 255 /* Map from voltage channel index to voltage register */ 256 257 static const s8 ltc4245_in_regs[] = { 258 LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN, 259 LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT, 260 }; 261 262 /* Map from current channel index to current register */ 263 264 static const s8 ltc4245_curr_regs[] = { 265 LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE, 266 }; 267 268 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel, 269 long *val) 270 { 271 struct ltc4245_data *data = ltc4245_update_device(dev); 272 273 switch (attr) { 274 case hwmon_curr_input: 275 *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 276 return 0; 277 case hwmon_curr_max_alarm: 278 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4)); 279 return 0; 280 default: 281 return -EOPNOTSUPP; 282 } 283 } 284 285 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val) 286 { 287 struct ltc4245_data *data = ltc4245_update_device(dev); 288 289 switch (attr) { 290 case hwmon_in_input: 291 if (channel < 8) { 292 *val = ltc4245_get_voltage(dev, 293 ltc4245_in_regs[channel]); 294 } else { 295 int regval = data->gpios[channel - 8]; 296 297 if (regval < 0) 298 return regval; 299 *val = regval * 10; 300 } 301 return 0; 302 case hwmon_in_min_alarm: 303 if (channel < 4) 304 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel)); 305 else 306 *val = !!(data->cregs[LTC4245_FAULT2] & 307 BIT(channel - 4)); 308 return 0; 309 default: 310 return -EOPNOTSUPP; 311 } 312 } 313 314 static int ltc4245_read_power(struct device *dev, u32 attr, int channel, 315 long *val) 316 { 317 unsigned long curr; 318 long voltage; 319 320 switch (attr) { 321 case hwmon_power_input: 322 (void)ltc4245_update_device(dev); 323 curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 324 voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]); 325 *val = abs(curr * voltage); 326 return 0; 327 default: 328 return -EOPNOTSUPP; 329 } 330 } 331 332 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type, 333 u32 attr, int channel, long *val) 334 { 335 336 switch (type) { 337 case hwmon_curr: 338 return ltc4245_read_curr(dev, attr, channel, val); 339 case hwmon_power: 340 return ltc4245_read_power(dev, attr, channel, val); 341 case hwmon_in: 342 return ltc4245_read_in(dev, attr, channel - 1, val); 343 default: 344 return -EOPNOTSUPP; 345 } 346 } 347 348 static umode_t ltc4245_is_visible(const void *_data, 349 enum hwmon_sensor_types type, 350 u32 attr, int channel) 351 { 352 const struct ltc4245_data *data = _data; 353 354 switch (type) { 355 case hwmon_in: 356 if (channel == 0) 357 return 0; 358 switch (attr) { 359 case hwmon_in_input: 360 if (channel > 9 && !data->use_extra_gpios) 361 return 0; 362 return 0444; 363 case hwmon_in_min_alarm: 364 if (channel > 8) 365 return 0; 366 return 0444; 367 default: 368 return 0; 369 } 370 case hwmon_curr: 371 switch (attr) { 372 case hwmon_curr_input: 373 case hwmon_curr_max_alarm: 374 return 0444; 375 default: 376 return 0; 377 } 378 case hwmon_power: 379 switch (attr) { 380 case hwmon_power_input: 381 return 0444; 382 default: 383 return 0; 384 } 385 default: 386 return 0; 387 } 388 } 389 390 static const struct hwmon_channel_info * const ltc4245_info[] = { 391 HWMON_CHANNEL_INFO(in, 392 HWMON_I_INPUT, 393 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 394 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 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, 402 HWMON_I_INPUT, 403 HWMON_I_INPUT), 404 HWMON_CHANNEL_INFO(curr, 405 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 406 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 407 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 408 HWMON_C_INPUT | HWMON_C_MAX_ALARM), 409 HWMON_CHANNEL_INFO(power, 410 HWMON_P_INPUT, 411 HWMON_P_INPUT, 412 HWMON_P_INPUT, 413 HWMON_P_INPUT), 414 NULL 415 }; 416 417 static const struct hwmon_ops ltc4245_hwmon_ops = { 418 .is_visible = ltc4245_is_visible, 419 .read = ltc4245_read, 420 }; 421 422 static const struct hwmon_chip_info ltc4245_chip_info = { 423 .ops = <c4245_hwmon_ops, 424 .info = ltc4245_info, 425 }; 426 427 static bool ltc4245_use_extra_gpios(struct i2c_client *client) 428 { 429 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 430 struct device_node *np = client->dev.of_node; 431 432 /* prefer platform data */ 433 if (pdata) 434 return pdata->use_extra_gpios; 435 436 /* fallback on OF */ 437 if (of_property_read_bool(np, "ltc4245,use-extra-gpios")) 438 return true; 439 440 return false; 441 } 442 443 static int ltc4245_probe(struct i2c_client *client) 444 { 445 struct i2c_adapter *adapter = client->adapter; 446 struct ltc4245_data *data; 447 struct device *hwmon_dev; 448 449 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 450 return -ENODEV; 451 452 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 453 if (!data) 454 return -ENOMEM; 455 456 data->client = client; 457 mutex_init(&data->update_lock); 458 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 459 460 /* Initialize the LTC4245 chip */ 461 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 462 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 463 464 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, 465 client->name, data, 466 <c4245_chip_info, 467 NULL); 468 return PTR_ERR_OR_ZERO(hwmon_dev); 469 } 470 471 static const struct i2c_device_id ltc4245_id[] = { 472 { "ltc4245", 0 }, 473 { } 474 }; 475 MODULE_DEVICE_TABLE(i2c, ltc4245_id); 476 477 /* This is the driver that will be inserted */ 478 static struct i2c_driver ltc4245_driver = { 479 .driver = { 480 .name = "ltc4245", 481 }, 482 .probe = ltc4245_probe, 483 .id_table = ltc4245_id, 484 }; 485 486 module_i2c_driver(ltc4245_driver); 487 488 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 489 MODULE_DESCRIPTION("LTC4245 driver"); 490 MODULE_LICENSE("GPL"); 491