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/jiffies.h> 22 #include <linux/platform_data/ltc4245.h> 23 24 /* Here are names of the chip's registers (a.k.a. commands) */ 25 enum ltc4245_cmd { 26 LTC4245_STATUS = 0x00, /* readonly */ 27 LTC4245_ALERT = 0x01, 28 LTC4245_CONTROL = 0x02, 29 LTC4245_ON = 0x03, 30 LTC4245_FAULT1 = 0x04, 31 LTC4245_FAULT2 = 0x05, 32 LTC4245_GPIO = 0x06, 33 LTC4245_ADCADR = 0x07, 34 35 LTC4245_12VIN = 0x10, 36 LTC4245_12VSENSE = 0x11, 37 LTC4245_12VOUT = 0x12, 38 LTC4245_5VIN = 0x13, 39 LTC4245_5VSENSE = 0x14, 40 LTC4245_5VOUT = 0x15, 41 LTC4245_3VIN = 0x16, 42 LTC4245_3VSENSE = 0x17, 43 LTC4245_3VOUT = 0x18, 44 LTC4245_VEEIN = 0x19, 45 LTC4245_VEESENSE = 0x1a, 46 LTC4245_VEEOUT = 0x1b, 47 LTC4245_GPIOADC = 0x1c, 48 }; 49 50 struct ltc4245_data { 51 struct i2c_client *client; 52 53 bool valid; 54 unsigned long last_updated; /* in jiffies */ 55 56 /* Control registers */ 57 u8 cregs[0x08]; 58 59 /* Voltage registers */ 60 u8 vregs[0x0d]; 61 62 /* GPIO ADC registers */ 63 bool use_extra_gpios; 64 int gpios[3]; 65 }; 66 67 /* 68 * Update the readings from the GPIO pins. If the driver has been configured to 69 * sample all GPIO's as analog voltages, a round-robin sampling method is used. 70 * Otherwise, only the configured GPIO pin is sampled. 71 * 72 * LOCKING: must hold data->update_lock 73 */ 74 static void ltc4245_update_gpios(struct device *dev) 75 { 76 struct ltc4245_data *data = dev_get_drvdata(dev); 77 struct i2c_client *client = data->client; 78 u8 gpio_curr, gpio_next, gpio_reg; 79 int i; 80 81 /* no extra gpio support, we're basically done */ 82 if (!data->use_extra_gpios) { 83 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; 84 return; 85 } 86 87 /* 88 * If the last reading was too long ago, then we mark all old GPIO 89 * readings as stale by setting them to -EAGAIN 90 */ 91 if (time_after(jiffies, data->last_updated + 5 * HZ)) { 92 for (i = 0; i < ARRAY_SIZE(data->gpios); i++) 93 data->gpios[i] = -EAGAIN; 94 } 95 96 /* 97 * Get the current GPIO pin 98 * 99 * The datasheet calls these GPIO[1-3], but we'll calculate the zero 100 * based array index instead, and call them GPIO[0-2]. This is much 101 * easier to think about. 102 */ 103 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6; 104 if (gpio_curr > 0) 105 gpio_curr -= 1; 106 107 /* Read the GPIO voltage from the GPIOADC register */ 108 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10]; 109 110 /* Find the next GPIO pin to read */ 111 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios); 112 113 /* 114 * Calculate the correct setting for the GPIO register so it will 115 * sample the next GPIO pin 116 */ 117 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6); 118 119 /* Update the GPIO register */ 120 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg); 121 122 /* Update saved data */ 123 data->cregs[LTC4245_GPIO] = gpio_reg; 124 } 125 126 static struct ltc4245_data *ltc4245_update_device(struct device *dev) 127 { 128 struct ltc4245_data *data = dev_get_drvdata(dev); 129 struct i2c_client *client = data->client; 130 s32 val; 131 int i; 132 133 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { 134 /* Read control registers -- 0x00 to 0x07 */ 135 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { 136 val = i2c_smbus_read_byte_data(client, i); 137 if (unlikely(val < 0)) 138 data->cregs[i] = 0; 139 else 140 data->cregs[i] = val; 141 } 142 143 /* Read voltage registers -- 0x10 to 0x1c */ 144 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { 145 val = i2c_smbus_read_byte_data(client, i+0x10); 146 if (unlikely(val < 0)) 147 data->vregs[i] = 0; 148 else 149 data->vregs[i] = val; 150 } 151 152 /* Update GPIO readings */ 153 ltc4245_update_gpios(dev); 154 155 data->last_updated = jiffies; 156 data->valid = true; 157 } 158 159 return data; 160 } 161 162 /* Return the voltage from the given register in millivolts */ 163 static int ltc4245_get_voltage(struct device *dev, u8 reg) 164 { 165 struct ltc4245_data *data = ltc4245_update_device(dev); 166 const u8 regval = data->vregs[reg - 0x10]; 167 u32 voltage = 0; 168 169 switch (reg) { 170 case LTC4245_12VIN: 171 case LTC4245_12VOUT: 172 voltage = regval * 55; 173 break; 174 case LTC4245_5VIN: 175 case LTC4245_5VOUT: 176 voltage = regval * 22; 177 break; 178 case LTC4245_3VIN: 179 case LTC4245_3VOUT: 180 voltage = regval * 15; 181 break; 182 case LTC4245_VEEIN: 183 case LTC4245_VEEOUT: 184 voltage = regval * -55; 185 break; 186 case LTC4245_GPIOADC: 187 voltage = regval * 10; 188 break; 189 default: 190 /* If we get here, the developer messed up */ 191 WARN_ON_ONCE(1); 192 break; 193 } 194 195 return voltage; 196 } 197 198 /* Return the current in the given sense register in milliAmperes */ 199 static unsigned int ltc4245_get_current(struct device *dev, u8 reg) 200 { 201 struct ltc4245_data *data = ltc4245_update_device(dev); 202 const u8 regval = data->vregs[reg - 0x10]; 203 unsigned int voltage; 204 unsigned int curr; 205 206 /* 207 * The strange looking conversions that follow are fixed-point 208 * math, since we cannot do floating point in the kernel. 209 * 210 * Step 1: convert sense register to microVolts 211 * Step 2: convert voltage to milliAmperes 212 * 213 * If you play around with the V=IR equation, you come up with 214 * the following: X uV / Y mOhm == Z mA 215 * 216 * With the resistors that are fractions of a milliOhm, we multiply 217 * the voltage and resistance by 10, to shift the decimal point. 218 * Now we can use the normal division operator again. 219 */ 220 221 switch (reg) { 222 case LTC4245_12VSENSE: 223 voltage = regval * 250; /* voltage in uV */ 224 curr = voltage / 50; /* sense resistor 50 mOhm */ 225 break; 226 case LTC4245_5VSENSE: 227 voltage = regval * 125; /* voltage in uV */ 228 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ 229 break; 230 case LTC4245_3VSENSE: 231 voltage = regval * 125; /* voltage in uV */ 232 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ 233 break; 234 case LTC4245_VEESENSE: 235 voltage = regval * 250; /* voltage in uV */ 236 curr = voltage / 100; /* sense resistor 100 mOhm */ 237 break; 238 default: 239 /* If we get here, the developer messed up */ 240 WARN_ON_ONCE(1); 241 curr = 0; 242 break; 243 } 244 245 return curr; 246 } 247 248 /* Map from voltage channel index to voltage register */ 249 250 static const s8 ltc4245_in_regs[] = { 251 LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN, 252 LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT, 253 }; 254 255 /* Map from current channel index to current register */ 256 257 static const s8 ltc4245_curr_regs[] = { 258 LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE, 259 }; 260 261 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel, 262 long *val) 263 { 264 struct ltc4245_data *data = ltc4245_update_device(dev); 265 266 switch (attr) { 267 case hwmon_curr_input: 268 *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 269 return 0; 270 case hwmon_curr_max_alarm: 271 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4)); 272 return 0; 273 default: 274 return -EOPNOTSUPP; 275 } 276 } 277 278 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val) 279 { 280 struct ltc4245_data *data = ltc4245_update_device(dev); 281 282 switch (attr) { 283 case hwmon_in_input: 284 if (channel < 8) { 285 *val = ltc4245_get_voltage(dev, 286 ltc4245_in_regs[channel]); 287 } else { 288 int regval = data->gpios[channel - 8]; 289 290 if (regval < 0) 291 return regval; 292 *val = regval * 10; 293 } 294 return 0; 295 case hwmon_in_min_alarm: 296 if (channel < 4) 297 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel)); 298 else 299 *val = !!(data->cregs[LTC4245_FAULT2] & 300 BIT(channel - 4)); 301 return 0; 302 default: 303 return -EOPNOTSUPP; 304 } 305 } 306 307 static int ltc4245_read_power(struct device *dev, u32 attr, int channel, 308 long *val) 309 { 310 unsigned long curr; 311 long voltage; 312 313 switch (attr) { 314 case hwmon_power_input: 315 (void)ltc4245_update_device(dev); 316 curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); 317 voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]); 318 *val = abs(curr * voltage); 319 return 0; 320 default: 321 return -EOPNOTSUPP; 322 } 323 } 324 325 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type, 326 u32 attr, int channel, long *val) 327 { 328 329 switch (type) { 330 case hwmon_curr: 331 return ltc4245_read_curr(dev, attr, channel, val); 332 case hwmon_power: 333 return ltc4245_read_power(dev, attr, channel, val); 334 case hwmon_in: 335 return ltc4245_read_in(dev, attr, channel - 1, val); 336 default: 337 return -EOPNOTSUPP; 338 } 339 } 340 341 static umode_t ltc4245_is_visible(const void *_data, 342 enum hwmon_sensor_types type, 343 u32 attr, int channel) 344 { 345 const struct ltc4245_data *data = _data; 346 347 switch (type) { 348 case hwmon_in: 349 if (channel == 0) 350 return 0; 351 switch (attr) { 352 case hwmon_in_input: 353 if (channel > 9 && !data->use_extra_gpios) 354 return 0; 355 return 0444; 356 case hwmon_in_min_alarm: 357 if (channel > 8) 358 return 0; 359 return 0444; 360 default: 361 return 0; 362 } 363 case hwmon_curr: 364 switch (attr) { 365 case hwmon_curr_input: 366 case hwmon_curr_max_alarm: 367 return 0444; 368 default: 369 return 0; 370 } 371 case hwmon_power: 372 switch (attr) { 373 case hwmon_power_input: 374 return 0444; 375 default: 376 return 0; 377 } 378 default: 379 return 0; 380 } 381 } 382 383 static const struct hwmon_channel_info * const ltc4245_info[] = { 384 HWMON_CHANNEL_INFO(in, 385 HWMON_I_INPUT, 386 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 387 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 388 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 389 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 390 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 391 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 392 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 393 HWMON_I_INPUT | HWMON_I_MIN_ALARM, 394 HWMON_I_INPUT, 395 HWMON_I_INPUT, 396 HWMON_I_INPUT), 397 HWMON_CHANNEL_INFO(curr, 398 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 399 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 400 HWMON_C_INPUT | HWMON_C_MAX_ALARM, 401 HWMON_C_INPUT | HWMON_C_MAX_ALARM), 402 HWMON_CHANNEL_INFO(power, 403 HWMON_P_INPUT, 404 HWMON_P_INPUT, 405 HWMON_P_INPUT, 406 HWMON_P_INPUT), 407 NULL 408 }; 409 410 static const struct hwmon_ops ltc4245_hwmon_ops = { 411 .is_visible = ltc4245_is_visible, 412 .read = ltc4245_read, 413 }; 414 415 static const struct hwmon_chip_info ltc4245_chip_info = { 416 .ops = <c4245_hwmon_ops, 417 .info = ltc4245_info, 418 }; 419 420 static bool ltc4245_use_extra_gpios(struct i2c_client *client) 421 { 422 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); 423 struct device_node *np = client->dev.of_node; 424 425 /* prefer platform data */ 426 if (pdata) 427 return pdata->use_extra_gpios; 428 429 /* fallback on OF */ 430 if (of_property_read_bool(np, "ltc4245,use-extra-gpios")) 431 return true; 432 433 return false; 434 } 435 436 static int ltc4245_probe(struct i2c_client *client) 437 { 438 struct i2c_adapter *adapter = client->adapter; 439 struct ltc4245_data *data; 440 struct device *hwmon_dev; 441 442 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 443 return -ENODEV; 444 445 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 446 if (!data) 447 return -ENOMEM; 448 449 data->client = client; 450 data->use_extra_gpios = ltc4245_use_extra_gpios(client); 451 452 /* Initialize the LTC4245 chip */ 453 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); 454 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); 455 456 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, 457 client->name, data, 458 <c4245_chip_info, 459 NULL); 460 return PTR_ERR_OR_ZERO(hwmon_dev); 461 } 462 463 static const struct i2c_device_id ltc4245_id[] = { 464 { "ltc4245" }, 465 { } 466 }; 467 MODULE_DEVICE_TABLE(i2c, ltc4245_id); 468 469 /* This is the driver that will be inserted */ 470 static struct i2c_driver ltc4245_driver = { 471 .driver = { 472 .name = "ltc4245", 473 }, 474 .probe = ltc4245_probe, 475 .id_table = ltc4245_id, 476 }; 477 478 module_i2c_driver(ltc4245_driver); 479 480 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 481 MODULE_DESCRIPTION("LTC4245 driver"); 482 MODULE_LICENSE("GPL"); 483