linux/drivers/hwmon/ltc4245.c
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   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) */
  26enum 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
  51struct 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 */
  76static 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
 128static 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 */
 170static 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 */
 206static 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
 257static 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
 264static const s8 ltc4245_curr_regs[] = {
 265        LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
 266};
 267
 268static 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
 285static 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
 314static 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
 332static 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
 348static 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
 390static 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
 417static const struct hwmon_ops ltc4245_hwmon_ops = {
 418        .is_visible = ltc4245_is_visible,
 419        .read = ltc4245_read,
 420};
 421
 422static const struct hwmon_chip_info ltc4245_chip_info = {
 423        .ops = &ltc4245_hwmon_ops,
 424        .info = ltc4245_info,
 425};
 426
 427static 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
 443static 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                                                         &ltc4245_chip_info,
 467                                                         NULL);
 468        return PTR_ERR_OR_ZERO(hwmon_dev);
 469}
 470
 471static const struct i2c_device_id ltc4245_id[] = {
 472        { "ltc4245", 0 },
 473        { }
 474};
 475MODULE_DEVICE_TABLE(i2c, ltc4245_id);
 476
 477/* This is the driver that will be inserted */
 478static struct i2c_driver ltc4245_driver = {
 479        .driver = {
 480                .name   = "ltc4245",
 481        },
 482        .probe_new      = ltc4245_probe,
 483        .id_table       = ltc4245_id,
 484};
 485
 486module_i2c_driver(ltc4245_driver);
 487
 488MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 489MODULE_DESCRIPTION("LTC4245 driver");
 490MODULE_LICENSE("GPL");
 491