root/drivers/hwmon/ltc4245.c

DEFINITIONS

1. ltc4245_update_gpios
2. ltc4245_update_device
3. ltc4245_get_voltage
4. ltc4245_get_current
5. ltc4245_read_curr
6. ltc4245_read_in
7. ltc4245_read_power
8. ltc4245_read
9. ltc4245_is_visible
10. ltc4245_use_extra_gpios
11. ltc4245_probe

   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 *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 = &ltc4245_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_find_property(np, "ltc4245,use-extra-gpios", NULL))
 438                 return true;
 439 
 440         return false;
 441 }
 442 
 443 static int ltc4245_probe(struct i2c_client *client,
 444                          const struct i2c_device_id *id)
 445 {
 446         struct i2c_adapter *adapter = client->adapter;
 447         struct ltc4245_data *data;
 448         struct device *hwmon_dev;
 449 
 450         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 451                 return -ENODEV;
 452 
 453         data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 454         if (!data)
 455                 return -ENOMEM;
 456 
 457         data->client = client;
 458         mutex_init(&data->update_lock);
 459         data->use_extra_gpios = ltc4245_use_extra_gpios(client);
 460 
 461         /* Initialize the LTC4245 chip */
 462         i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
 463         i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
 464 
 465         hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
 466                                                          client->name, data,
 467                                                          &ltc4245_chip_info,
 468                                                          NULL);
 469         return PTR_ERR_OR_ZERO(hwmon_dev);
 470 }
 471 
 472 static const struct i2c_device_id ltc4245_id[] = {
 473         { "ltc4245", 0 },
 474         { }
 475 };
 476 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
 477 
 478 /* This is the driver that will be inserted */
 479 static struct i2c_driver ltc4245_driver = {
 480         .driver = {
 481                 .name   = "ltc4245",
 482         },
 483         .probe          = ltc4245_probe,
 484         .id_table       = ltc4245_id,
 485 };
 486 
 487 module_i2c_driver(ltc4245_driver);
 488 
 489 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 490 MODULE_DESCRIPTION("LTC4245 driver");
 491 MODULE_LICENSE("GPL");