linux/drivers/hwmon/ltc4245.c
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   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/err.h>
  20#include <linux/slab.h>
  21#include <linux/i2c.h>
  22#include <linux/hwmon.h>
  23#include <linux/hwmon-sysfs.h>
  24#include <linux/jiffies.h>
  25#include <linux/i2c/ltc4245.h>
  26
  27/* Here are names of the chip's registers (a.k.a. commands) */
  28enum ltc4245_cmd {
  29        LTC4245_STATUS                  = 0x00, /* readonly */
  30        LTC4245_ALERT                   = 0x01,
  31        LTC4245_CONTROL                 = 0x02,
  32        LTC4245_ON                      = 0x03,
  33        LTC4245_FAULT1                  = 0x04,
  34        LTC4245_FAULT2                  = 0x05,
  35        LTC4245_GPIO                    = 0x06,
  36        LTC4245_ADCADR                  = 0x07,
  37
  38        LTC4245_12VIN                   = 0x10,
  39        LTC4245_12VSENSE                = 0x11,
  40        LTC4245_12VOUT                  = 0x12,
  41        LTC4245_5VIN                    = 0x13,
  42        LTC4245_5VSENSE                 = 0x14,
  43        LTC4245_5VOUT                   = 0x15,
  44        LTC4245_3VIN                    = 0x16,
  45        LTC4245_3VSENSE                 = 0x17,
  46        LTC4245_3VOUT                   = 0x18,
  47        LTC4245_VEEIN                   = 0x19,
  48        LTC4245_VEESENSE                = 0x1a,
  49        LTC4245_VEEOUT                  = 0x1b,
  50        LTC4245_GPIOADC                 = 0x1c,
  51};
  52
  53struct ltc4245_data {
  54        struct device *hwmon_dev;
  55
  56        struct mutex update_lock;
  57        bool valid;
  58        unsigned long last_updated; /* in jiffies */
  59
  60        /* Control registers */
  61        u8 cregs[0x08];
  62
  63        /* Voltage registers */
  64        u8 vregs[0x0d];
  65
  66        /* GPIO ADC registers */
  67        bool use_extra_gpios;
  68        int gpios[3];
  69};
  70
  71/*
  72 * Update the readings from the GPIO pins. If the driver has been configured to
  73 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
  74 * Otherwise, only the configured GPIO pin is sampled.
  75 *
  76 * LOCKING: must hold data->update_lock
  77 */
  78static void ltc4245_update_gpios(struct device *dev)
  79{
  80        struct i2c_client *client = to_i2c_client(dev);
  81        struct ltc4245_data *data = i2c_get_clientdata(client);
  82        u8 gpio_curr, gpio_next, gpio_reg;
  83        int i;
  84
  85        /* no extra gpio support, we're basically done */
  86        if (!data->use_extra_gpios) {
  87                data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
  88                return;
  89        }
  90
  91        /*
  92         * If the last reading was too long ago, then we mark all old GPIO
  93         * readings as stale by setting them to -EAGAIN
  94         */
  95        if (time_after(jiffies, data->last_updated + 5 * HZ)) {
  96                dev_dbg(&client->dev, "Marking GPIOs invalid\n");
  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
 131static struct ltc4245_data *ltc4245_update_device(struct device *dev)
 132{
 133        struct i2c_client *client = to_i2c_client(dev);
 134        struct ltc4245_data *data = i2c_get_clientdata(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                dev_dbg(&client->dev, "Starting ltc4245 update\n");
 143
 144                /* Read control registers -- 0x00 to 0x07 */
 145                for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
 146                        val = i2c_smbus_read_byte_data(client, i);
 147                        if (unlikely(val < 0))
 148                                data->cregs[i] = 0;
 149                        else
 150                                data->cregs[i] = val;
 151                }
 152
 153                /* Read voltage registers -- 0x10 to 0x1c */
 154                for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
 155                        val = i2c_smbus_read_byte_data(client, i+0x10);
 156                        if (unlikely(val < 0))
 157                                data->vregs[i] = 0;
 158                        else
 159                                data->vregs[i] = val;
 160                }
 161
 162                /* Update GPIO readings */
 163                ltc4245_update_gpios(dev);
 164
 165                data->last_updated = jiffies;
 166                data->valid = 1;
 167        }
 168
 169        mutex_unlock(&data->update_lock);
 170
 171        return data;
 172}
 173
 174/* Return the voltage from the given register in millivolts */
 175static int ltc4245_get_voltage(struct device *dev, u8 reg)
 176{
 177        struct ltc4245_data *data = ltc4245_update_device(dev);
 178        const u8 regval = data->vregs[reg - 0x10];
 179        u32 voltage = 0;
 180
 181        switch (reg) {
 182        case LTC4245_12VIN:
 183        case LTC4245_12VOUT:
 184                voltage = regval * 55;
 185                break;
 186        case LTC4245_5VIN:
 187        case LTC4245_5VOUT:
 188                voltage = regval * 22;
 189                break;
 190        case LTC4245_3VIN:
 191        case LTC4245_3VOUT:
 192                voltage = regval * 15;
 193                break;
 194        case LTC4245_VEEIN:
 195        case LTC4245_VEEOUT:
 196                voltage = regval * -55;
 197                break;
 198        case LTC4245_GPIOADC:
 199                voltage = regval * 10;
 200                break;
 201        default:
 202                /* If we get here, the developer messed up */
 203                WARN_ON_ONCE(1);
 204                break;
 205        }
 206
 207        return voltage;
 208}
 209
 210/* Return the current in the given sense register in milliAmperes */
 211static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
 212{
 213        struct ltc4245_data *data = ltc4245_update_device(dev);
 214        const u8 regval = data->vregs[reg - 0x10];
 215        unsigned int voltage;
 216        unsigned int curr;
 217
 218        /*
 219         * The strange looking conversions that follow are fixed-point
 220         * math, since we cannot do floating point in the kernel.
 221         *
 222         * Step 1: convert sense register to microVolts
 223         * Step 2: convert voltage to milliAmperes
 224         *
 225         * If you play around with the V=IR equation, you come up with
 226         * the following: X uV / Y mOhm == Z mA
 227         *
 228         * With the resistors that are fractions of a milliOhm, we multiply
 229         * the voltage and resistance by 10, to shift the decimal point.
 230         * Now we can use the normal division operator again.
 231         */
 232
 233        switch (reg) {
 234        case LTC4245_12VSENSE:
 235                voltage = regval * 250; /* voltage in uV */
 236                curr = voltage / 50; /* sense resistor 50 mOhm */
 237                break;
 238        case LTC4245_5VSENSE:
 239                voltage = regval * 125; /* voltage in uV */
 240                curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
 241                break;
 242        case LTC4245_3VSENSE:
 243                voltage = regval * 125; /* voltage in uV */
 244                curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
 245                break;
 246        case LTC4245_VEESENSE:
 247                voltage = regval * 250; /* voltage in uV */
 248                curr = voltage / 100; /* sense resistor 100 mOhm */
 249                break;
 250        default:
 251                /* If we get here, the developer messed up */
 252                WARN_ON_ONCE(1);
 253                curr = 0;
 254                break;
 255        }
 256
 257        return curr;
 258}
 259
 260static ssize_t ltc4245_show_voltage(struct device *dev,
 261                                    struct device_attribute *da,
 262                                    char *buf)
 263{
 264        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 265        const int voltage = ltc4245_get_voltage(dev, attr->index);
 266
 267        return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
 268}
 269
 270static ssize_t ltc4245_show_current(struct device *dev,
 271                                    struct device_attribute *da,
 272                                    char *buf)
 273{
 274        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 275        const unsigned int curr = ltc4245_get_current(dev, attr->index);
 276
 277        return snprintf(buf, PAGE_SIZE, "%u\n", curr);
 278}
 279
 280static ssize_t ltc4245_show_power(struct device *dev,
 281                                  struct device_attribute *da,
 282                                  char *buf)
 283{
 284        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 285        const unsigned int curr = ltc4245_get_current(dev, attr->index);
 286        const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);
 287
 288        /* current in mA * voltage in mV == power in uW */
 289        const unsigned int power = abs(output_voltage * curr);
 290
 291        return snprintf(buf, PAGE_SIZE, "%u\n", power);
 292}
 293
 294static ssize_t ltc4245_show_alarm(struct device *dev,
 295                                          struct device_attribute *da,
 296                                          char *buf)
 297{
 298        struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
 299        struct ltc4245_data *data = ltc4245_update_device(dev);
 300        const u8 reg = data->cregs[attr->index];
 301        const u32 mask = attr->nr;
 302
 303        return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
 304}
 305
 306static ssize_t ltc4245_show_gpio(struct device *dev,
 307                                 struct device_attribute *da,
 308                                 char *buf)
 309{
 310        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 311        struct ltc4245_data *data = ltc4245_update_device(dev);
 312        int val = data->gpios[attr->index];
 313
 314        /* handle stale GPIO's */
 315        if (val < 0)
 316                return val;
 317
 318        /* Convert to millivolts and print */
 319        return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
 320}
 321
 322/*
 323 * These macros are used below in constructing device attribute objects
 324 * for use with sysfs_create_group() to make a sysfs device file
 325 * for each register.
 326 */
 327
 328#define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \
 329        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 330        ltc4245_show_voltage, NULL, ltc4245_cmd_idx)
 331
 332#define LTC4245_CURRENT(name, ltc4245_cmd_idx) \
 333        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 334        ltc4245_show_current, NULL, ltc4245_cmd_idx)
 335
 336#define LTC4245_POWER(name, ltc4245_cmd_idx) \
 337        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 338        ltc4245_show_power, NULL, ltc4245_cmd_idx)
 339
 340#define LTC4245_ALARM(name, mask, reg) \
 341        static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
 342        ltc4245_show_alarm, NULL, (mask), reg)
 343
 344#define LTC4245_GPIO_VOLTAGE(name, gpio_num) \
 345        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 346        ltc4245_show_gpio, NULL, gpio_num)
 347
 348/* Construct a sensor_device_attribute structure for each register */
 349
 350/* Input voltages */
 351LTC4245_VOLTAGE(in1_input,                      LTC4245_12VIN);
 352LTC4245_VOLTAGE(in2_input,                      LTC4245_5VIN);
 353LTC4245_VOLTAGE(in3_input,                      LTC4245_3VIN);
 354LTC4245_VOLTAGE(in4_input,                      LTC4245_VEEIN);
 355
 356/* Input undervoltage alarms */
 357LTC4245_ALARM(in1_min_alarm,    (1 << 0),       LTC4245_FAULT1);
 358LTC4245_ALARM(in2_min_alarm,    (1 << 1),       LTC4245_FAULT1);
 359LTC4245_ALARM(in3_min_alarm,    (1 << 2),       LTC4245_FAULT1);
 360LTC4245_ALARM(in4_min_alarm,    (1 << 3),       LTC4245_FAULT1);
 361
 362/* Currents (via sense resistor) */
 363LTC4245_CURRENT(curr1_input,                    LTC4245_12VSENSE);
 364LTC4245_CURRENT(curr2_input,                    LTC4245_5VSENSE);
 365LTC4245_CURRENT(curr3_input,                    LTC4245_3VSENSE);
 366LTC4245_CURRENT(curr4_input,                    LTC4245_VEESENSE);
 367
 368/* Overcurrent alarms */
 369LTC4245_ALARM(curr1_max_alarm,  (1 << 4),       LTC4245_FAULT1);
 370LTC4245_ALARM(curr2_max_alarm,  (1 << 5),       LTC4245_FAULT1);
 371LTC4245_ALARM(curr3_max_alarm,  (1 << 6),       LTC4245_FAULT1);
 372LTC4245_ALARM(curr4_max_alarm,  (1 << 7),       LTC4245_FAULT1);
 373
 374/* Output voltages */
 375LTC4245_VOLTAGE(in5_input,                      LTC4245_12VOUT);
 376LTC4245_VOLTAGE(in6_input,                      LTC4245_5VOUT);
 377LTC4245_VOLTAGE(in7_input,                      LTC4245_3VOUT);
 378LTC4245_VOLTAGE(in8_input,                      LTC4245_VEEOUT);
 379
 380/* Power Bad alarms */
 381LTC4245_ALARM(in5_min_alarm,    (1 << 0),       LTC4245_FAULT2);
 382LTC4245_ALARM(in6_min_alarm,    (1 << 1),       LTC4245_FAULT2);
 383LTC4245_ALARM(in7_min_alarm,    (1 << 2),       LTC4245_FAULT2);
 384LTC4245_ALARM(in8_min_alarm,    (1 << 3),       LTC4245_FAULT2);
 385
 386/* GPIO voltages */
 387LTC4245_GPIO_VOLTAGE(in9_input,                 0);
 388LTC4245_GPIO_VOLTAGE(in10_input,                1);
 389LTC4245_GPIO_VOLTAGE(in11_input,                2);
 390
 391/* Power Consumption (virtual) */
 392LTC4245_POWER(power1_input,                     LTC4245_12VSENSE);
 393LTC4245_POWER(power2_input,                     LTC4245_5VSENSE);
 394LTC4245_POWER(power3_input,                     LTC4245_3VSENSE);
 395LTC4245_POWER(power4_input,                     LTC4245_VEESENSE);
 396
 397/*
 398 * Finally, construct an array of pointers to members of the above objects,
 399 * as required for sysfs_create_group()
 400 */
 401static struct attribute *ltc4245_std_attributes[] = {
 402        &sensor_dev_attr_in1_input.dev_attr.attr,
 403        &sensor_dev_attr_in2_input.dev_attr.attr,
 404        &sensor_dev_attr_in3_input.dev_attr.attr,
 405        &sensor_dev_attr_in4_input.dev_attr.attr,
 406
 407        &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 408        &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 409        &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
 410        &sensor_dev_attr_in4_min_alarm.dev_attr.attr,
 411
 412        &sensor_dev_attr_curr1_input.dev_attr.attr,
 413        &sensor_dev_attr_curr2_input.dev_attr.attr,
 414        &sensor_dev_attr_curr3_input.dev_attr.attr,
 415        &sensor_dev_attr_curr4_input.dev_attr.attr,
 416
 417        &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 418        &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
 419        &sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
 420        &sensor_dev_attr_curr4_max_alarm.dev_attr.attr,
 421
 422        &sensor_dev_attr_in5_input.dev_attr.attr,
 423        &sensor_dev_attr_in6_input.dev_attr.attr,
 424        &sensor_dev_attr_in7_input.dev_attr.attr,
 425        &sensor_dev_attr_in8_input.dev_attr.attr,
 426
 427        &sensor_dev_attr_in5_min_alarm.dev_attr.attr,
 428        &sensor_dev_attr_in6_min_alarm.dev_attr.attr,
 429        &sensor_dev_attr_in7_min_alarm.dev_attr.attr,
 430        &sensor_dev_attr_in8_min_alarm.dev_attr.attr,
 431
 432        &sensor_dev_attr_in9_input.dev_attr.attr,
 433
 434        &sensor_dev_attr_power1_input.dev_attr.attr,
 435        &sensor_dev_attr_power2_input.dev_attr.attr,
 436        &sensor_dev_attr_power3_input.dev_attr.attr,
 437        &sensor_dev_attr_power4_input.dev_attr.attr,
 438
 439        NULL,
 440};
 441
 442static struct attribute *ltc4245_gpio_attributes[] = {
 443        &sensor_dev_attr_in10_input.dev_attr.attr,
 444        &sensor_dev_attr_in11_input.dev_attr.attr,
 445        NULL,
 446};
 447
 448static const struct attribute_group ltc4245_std_group = {
 449        .attrs = ltc4245_std_attributes,
 450};
 451
 452static const struct attribute_group ltc4245_gpio_group = {
 453        .attrs = ltc4245_gpio_attributes,
 454};
 455
 456static int ltc4245_sysfs_create_groups(struct i2c_client *client)
 457{
 458        struct ltc4245_data *data = i2c_get_clientdata(client);
 459        struct device *dev = &client->dev;
 460        int ret;
 461
 462        /* register the standard sysfs attributes */
 463        ret = sysfs_create_group(&dev->kobj, &ltc4245_std_group);
 464        if (ret) {
 465                dev_err(dev, "unable to register standard attributes\n");
 466                return ret;
 467        }
 468
 469        /* if we're using the extra gpio support, register it's attributes */
 470        if (data->use_extra_gpios) {
 471                ret = sysfs_create_group(&dev->kobj, &ltc4245_gpio_group);
 472                if (ret) {
 473                        dev_err(dev, "unable to register gpio attributes\n");
 474                        sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
 475                        return ret;
 476                }
 477        }
 478
 479        return 0;
 480}
 481
 482static void ltc4245_sysfs_remove_groups(struct i2c_client *client)
 483{
 484        struct ltc4245_data *data = i2c_get_clientdata(client);
 485        struct device *dev = &client->dev;
 486
 487        if (data->use_extra_gpios)
 488                sysfs_remove_group(&dev->kobj, &ltc4245_gpio_group);
 489
 490        sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
 491}
 492
 493static bool ltc4245_use_extra_gpios(struct i2c_client *client)
 494{
 495        struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
 496#ifdef CONFIG_OF
 497        struct device_node *np = client->dev.of_node;
 498#endif
 499
 500        /* prefer platform data */
 501        if (pdata)
 502                return pdata->use_extra_gpios;
 503
 504#ifdef CONFIG_OF
 505        /* fallback on OF */
 506        if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
 507                return true;
 508#endif
 509
 510        return false;
 511}
 512
 513static int ltc4245_probe(struct i2c_client *client,
 514                         const struct i2c_device_id *id)
 515{
 516        struct i2c_adapter *adapter = client->adapter;
 517        struct ltc4245_data *data;
 518        int ret;
 519
 520        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 521                return -ENODEV;
 522
 523        data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 524        if (!data)
 525                return -ENOMEM;
 526
 527        i2c_set_clientdata(client, data);
 528        mutex_init(&data->update_lock);
 529        data->use_extra_gpios = ltc4245_use_extra_gpios(client);
 530
 531        /* Initialize the LTC4245 chip */
 532        i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
 533        i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
 534
 535        /* Register sysfs hooks */
 536        ret = ltc4245_sysfs_create_groups(client);
 537        if (ret)
 538                return ret;
 539
 540        data->hwmon_dev = hwmon_device_register(&client->dev);
 541        if (IS_ERR(data->hwmon_dev)) {
 542                ret = PTR_ERR(data->hwmon_dev);
 543                goto out_hwmon_device_register;
 544        }
 545
 546        return 0;
 547
 548out_hwmon_device_register:
 549        ltc4245_sysfs_remove_groups(client);
 550        return ret;
 551}
 552
 553static int ltc4245_remove(struct i2c_client *client)
 554{
 555        struct ltc4245_data *data = i2c_get_clientdata(client);
 556
 557        hwmon_device_unregister(data->hwmon_dev);
 558        ltc4245_sysfs_remove_groups(client);
 559
 560        return 0;
 561}
 562
 563static const struct i2c_device_id ltc4245_id[] = {
 564        { "ltc4245", 0 },
 565        { }
 566};
 567MODULE_DEVICE_TABLE(i2c, ltc4245_id);
 568
 569/* This is the driver that will be inserted */
 570static struct i2c_driver ltc4245_driver = {
 571        .driver = {
 572                .name   = "ltc4245",
 573        },
 574        .probe          = ltc4245_probe,
 575        .remove         = ltc4245_remove,
 576        .id_table       = ltc4245_id,
 577};
 578
 579module_i2c_driver(ltc4245_driver);
 580
 581MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 582MODULE_DESCRIPTION("LTC4245 driver");
 583MODULE_LICENSE("GPL");
 584
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