drivers/hwmon/ltc4245.c

   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         &ltc4245_in,
 442         &ltc4245_curr,
 443         &ltc4245_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 = &ltc4245_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                                                          &ltc4245_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");