linux/drivers/hwmon/gpio-fan.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
   4 *
   5 * Copyright (C) 2010 LaCie
   6 *
   7 * Author: Simon Guinot <sguinot@lacie.com>
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/init.h>
  12#include <linux/slab.h>
  13#include <linux/interrupt.h>
  14#include <linux/irq.h>
  15#include <linux/platform_device.h>
  16#include <linux/err.h>
  17#include <linux/mutex.h>
  18#include <linux/hwmon.h>
  19#include <linux/gpio/consumer.h>
  20#include <linux/of.h>
  21#include <linux/of_platform.h>
  22#include <linux/thermal.h>
  23
  24struct gpio_fan_speed {
  25        int rpm;
  26        int ctrl_val;
  27};
  28
  29struct gpio_fan_data {
  30        struct device           *dev;
  31        struct device           *hwmon_dev;
  32        /* Cooling device if any */
  33        struct thermal_cooling_device *cdev;
  34        struct mutex            lock; /* lock GPIOs operations. */
  35        int                     num_gpios;
  36        struct gpio_desc        **gpios;
  37        int                     num_speed;
  38        struct gpio_fan_speed   *speed;
  39        int                     speed_index;
  40#ifdef CONFIG_PM_SLEEP
  41        int                     resume_speed;
  42#endif
  43        bool                    pwm_enable;
  44        struct gpio_desc        *alarm_gpio;
  45        struct work_struct      alarm_work;
  46};
  47
  48/*
  49 * Alarm GPIO.
  50 */
  51
  52static void fan_alarm_notify(struct work_struct *ws)
  53{
  54        struct gpio_fan_data *fan_data =
  55                container_of(ws, struct gpio_fan_data, alarm_work);
  56
  57        sysfs_notify(&fan_data->hwmon_dev->kobj, NULL, "fan1_alarm");
  58        kobject_uevent(&fan_data->hwmon_dev->kobj, KOBJ_CHANGE);
  59}
  60
  61static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
  62{
  63        struct gpio_fan_data *fan_data = dev_id;
  64
  65        schedule_work(&fan_data->alarm_work);
  66
  67        return IRQ_NONE;
  68}
  69
  70static ssize_t fan1_alarm_show(struct device *dev,
  71                               struct device_attribute *attr, char *buf)
  72{
  73        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
  74
  75        return sprintf(buf, "%d\n",
  76                       gpiod_get_value_cansleep(fan_data->alarm_gpio));
  77}
  78
  79static DEVICE_ATTR_RO(fan1_alarm);
  80
  81static int fan_alarm_init(struct gpio_fan_data *fan_data)
  82{
  83        int alarm_irq;
  84        struct device *dev = fan_data->dev;
  85
  86        /*
  87         * If the alarm GPIO don't support interrupts, just leave
  88         * without initializing the fail notification support.
  89         */
  90        alarm_irq = gpiod_to_irq(fan_data->alarm_gpio);
  91        if (alarm_irq <= 0)
  92                return 0;
  93
  94        INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
  95        irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
  96        return devm_request_irq(dev, alarm_irq, fan_alarm_irq_handler,
  97                                IRQF_SHARED, "GPIO fan alarm", fan_data);
  98}
  99
 100/*
 101 * Control GPIOs.
 102 */
 103
 104/* Must be called with fan_data->lock held, except during initialization. */
 105static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
 106{
 107        int i;
 108
 109        for (i = 0; i < fan_data->num_gpios; i++)
 110                gpiod_set_value_cansleep(fan_data->gpios[i],
 111                                         (ctrl_val >> i) & 1);
 112}
 113
 114static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
 115{
 116        int i;
 117        int ctrl_val = 0;
 118
 119        for (i = 0; i < fan_data->num_gpios; i++) {
 120                int value;
 121
 122                value = gpiod_get_value_cansleep(fan_data->gpios[i]);
 123                ctrl_val |= (value << i);
 124        }
 125        return ctrl_val;
 126}
 127
 128/* Must be called with fan_data->lock held, except during initialization. */
 129static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
 130{
 131        if (fan_data->speed_index == speed_index)
 132                return;
 133
 134        __set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
 135        fan_data->speed_index = speed_index;
 136}
 137
 138static int get_fan_speed_index(struct gpio_fan_data *fan_data)
 139{
 140        int ctrl_val = __get_fan_ctrl(fan_data);
 141        int i;
 142
 143        for (i = 0; i < fan_data->num_speed; i++)
 144                if (fan_data->speed[i].ctrl_val == ctrl_val)
 145                        return i;
 146
 147        dev_warn(fan_data->dev,
 148                 "missing speed array entry for GPIO value 0x%x\n", ctrl_val);
 149
 150        return -ENODEV;
 151}
 152
 153static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
 154{
 155        struct gpio_fan_speed *speed = fan_data->speed;
 156        int i;
 157
 158        for (i = 0; i < fan_data->num_speed; i++)
 159                if (speed[i].rpm >= rpm)
 160                        return i;
 161
 162        return fan_data->num_speed - 1;
 163}
 164
 165static ssize_t pwm1_show(struct device *dev, struct device_attribute *attr,
 166                         char *buf)
 167{
 168        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 169        u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);
 170
 171        return sprintf(buf, "%d\n", pwm);
 172}
 173
 174static ssize_t pwm1_store(struct device *dev, struct device_attribute *attr,
 175                          const char *buf, size_t count)
 176{
 177        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 178        unsigned long pwm;
 179        int speed_index;
 180        int ret = count;
 181
 182        if (kstrtoul(buf, 10, &pwm) || pwm > 255)
 183                return -EINVAL;
 184
 185        mutex_lock(&fan_data->lock);
 186
 187        if (!fan_data->pwm_enable) {
 188                ret = -EPERM;
 189                goto exit_unlock;
 190        }
 191
 192        speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
 193        set_fan_speed(fan_data, speed_index);
 194
 195exit_unlock:
 196        mutex_unlock(&fan_data->lock);
 197
 198        return ret;
 199}
 200
 201static ssize_t pwm1_enable_show(struct device *dev,
 202                                struct device_attribute *attr, char *buf)
 203{
 204        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 205
 206        return sprintf(buf, "%d\n", fan_data->pwm_enable);
 207}
 208
 209static ssize_t pwm1_enable_store(struct device *dev,
 210                                 struct device_attribute *attr,
 211                                 const char *buf, size_t count)
 212{
 213        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 214        unsigned long val;
 215
 216        if (kstrtoul(buf, 10, &val) || val > 1)
 217                return -EINVAL;
 218
 219        if (fan_data->pwm_enable == val)
 220                return count;
 221
 222        mutex_lock(&fan_data->lock);
 223
 224        fan_data->pwm_enable = val;
 225
 226        /* Disable manual control mode: set fan at full speed. */
 227        if (val == 0)
 228                set_fan_speed(fan_data, fan_data->num_speed - 1);
 229
 230        mutex_unlock(&fan_data->lock);
 231
 232        return count;
 233}
 234
 235static ssize_t pwm1_mode_show(struct device *dev,
 236                              struct device_attribute *attr, char *buf)
 237{
 238        return sprintf(buf, "0\n");
 239}
 240
 241static ssize_t fan1_min_show(struct device *dev,
 242                             struct device_attribute *attr, char *buf)
 243{
 244        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 245
 246        return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
 247}
 248
 249static ssize_t fan1_max_show(struct device *dev,
 250                             struct device_attribute *attr, char *buf)
 251{
 252        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 253
 254        return sprintf(buf, "%d\n",
 255                       fan_data->speed[fan_data->num_speed - 1].rpm);
 256}
 257
 258static ssize_t fan1_input_show(struct device *dev,
 259                               struct device_attribute *attr, char *buf)
 260{
 261        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 262
 263        return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
 264}
 265
 266static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
 267                       const char *buf, size_t count)
 268{
 269        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 270        unsigned long rpm;
 271        int ret = count;
 272
 273        if (kstrtoul(buf, 10, &rpm))
 274                return -EINVAL;
 275
 276        mutex_lock(&fan_data->lock);
 277
 278        if (!fan_data->pwm_enable) {
 279                ret = -EPERM;
 280                goto exit_unlock;
 281        }
 282
 283        set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));
 284
 285exit_unlock:
 286        mutex_unlock(&fan_data->lock);
 287
 288        return ret;
 289}
 290
 291static DEVICE_ATTR_RW(pwm1);
 292static DEVICE_ATTR_RW(pwm1_enable);
 293static DEVICE_ATTR_RO(pwm1_mode);
 294static DEVICE_ATTR_RO(fan1_min);
 295static DEVICE_ATTR_RO(fan1_max);
 296static DEVICE_ATTR_RO(fan1_input);
 297static DEVICE_ATTR(fan1_target, 0644, fan1_input_show, set_rpm);
 298
 299static umode_t gpio_fan_is_visible(struct kobject *kobj,
 300                                   struct attribute *attr, int index)
 301{
 302        struct device *dev = container_of(kobj, struct device, kobj);
 303        struct gpio_fan_data *data = dev_get_drvdata(dev);
 304
 305        if (index == 0 && !data->alarm_gpio)
 306                return 0;
 307        if (index > 0 && !data->gpios)
 308                return 0;
 309
 310        return attr->mode;
 311}
 312
 313static struct attribute *gpio_fan_attributes[] = {
 314        &dev_attr_fan1_alarm.attr,              /* 0 */
 315        &dev_attr_pwm1.attr,                    /* 1 */
 316        &dev_attr_pwm1_enable.attr,
 317        &dev_attr_pwm1_mode.attr,
 318        &dev_attr_fan1_input.attr,
 319        &dev_attr_fan1_target.attr,
 320        &dev_attr_fan1_min.attr,
 321        &dev_attr_fan1_max.attr,
 322        NULL
 323};
 324
 325static const struct attribute_group gpio_fan_group = {
 326        .attrs = gpio_fan_attributes,
 327        .is_visible = gpio_fan_is_visible,
 328};
 329
 330static const struct attribute_group *gpio_fan_groups[] = {
 331        &gpio_fan_group,
 332        NULL
 333};
 334
 335static int fan_ctrl_init(struct gpio_fan_data *fan_data)
 336{
 337        int num_gpios = fan_data->num_gpios;
 338        struct gpio_desc **gpios = fan_data->gpios;
 339        int i, err;
 340
 341        for (i = 0; i < num_gpios; i++) {
 342                /*
 343                 * The GPIO descriptors were retrieved with GPIOD_ASIS so here
 344                 * we set the GPIO into output mode, carefully preserving the
 345                 * current value by setting it to whatever it is already set
 346                 * (no surprise changes in default fan speed).
 347                 */
 348                err = gpiod_direction_output(gpios[i],
 349                                        gpiod_get_value_cansleep(gpios[i]));
 350                if (err)
 351                        return err;
 352        }
 353
 354        fan_data->pwm_enable = true; /* Enable manual fan speed control. */
 355        fan_data->speed_index = get_fan_speed_index(fan_data);
 356        if (fan_data->speed_index < 0)
 357                return fan_data->speed_index;
 358
 359        return 0;
 360}
 361
 362static int gpio_fan_get_max_state(struct thermal_cooling_device *cdev,
 363                                  unsigned long *state)
 364{
 365        struct gpio_fan_data *fan_data = cdev->devdata;
 366
 367        if (!fan_data)
 368                return -EINVAL;
 369
 370        *state = fan_data->num_speed - 1;
 371        return 0;
 372}
 373
 374static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
 375                                  unsigned long *state)
 376{
 377        struct gpio_fan_data *fan_data = cdev->devdata;
 378
 379        if (!fan_data)
 380                return -EINVAL;
 381
 382        *state = fan_data->speed_index;
 383        return 0;
 384}
 385
 386static int gpio_fan_set_cur_state(struct thermal_cooling_device *cdev,
 387                                  unsigned long state)
 388{
 389        struct gpio_fan_data *fan_data = cdev->devdata;
 390
 391        if (!fan_data)
 392                return -EINVAL;
 393
 394        set_fan_speed(fan_data, state);
 395        return 0;
 396}
 397
 398static const struct thermal_cooling_device_ops gpio_fan_cool_ops = {
 399        .get_max_state = gpio_fan_get_max_state,
 400        .get_cur_state = gpio_fan_get_cur_state,
 401        .set_cur_state = gpio_fan_set_cur_state,
 402};
 403
 404/*
 405 * Translate OpenFirmware node properties into platform_data
 406 */
 407static int gpio_fan_get_of_data(struct gpio_fan_data *fan_data)
 408{
 409        struct gpio_fan_speed *speed;
 410        struct device *dev = fan_data->dev;
 411        struct device_node *np = dev->of_node;
 412        struct gpio_desc **gpios;
 413        unsigned i;
 414        u32 u;
 415        struct property *prop;
 416        const __be32 *p;
 417
 418        /* Alarm GPIO if one exists */
 419        fan_data->alarm_gpio = devm_gpiod_get_optional(dev, "alarm", GPIOD_IN);
 420        if (IS_ERR(fan_data->alarm_gpio))
 421                return PTR_ERR(fan_data->alarm_gpio);
 422
 423        /* Fill GPIO pin array */
 424        fan_data->num_gpios = gpiod_count(dev, NULL);
 425        if (fan_data->num_gpios <= 0) {
 426                if (fan_data->alarm_gpio)
 427                        return 0;
 428                dev_err(dev, "DT properties empty / missing");
 429                return -ENODEV;
 430        }
 431        gpios = devm_kcalloc(dev,
 432                             fan_data->num_gpios, sizeof(struct gpio_desc *),
 433                             GFP_KERNEL);
 434        if (!gpios)
 435                return -ENOMEM;
 436        for (i = 0; i < fan_data->num_gpios; i++) {
 437                gpios[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
 438                if (IS_ERR(gpios[i]))
 439                        return PTR_ERR(gpios[i]);
 440        }
 441        fan_data->gpios = gpios;
 442
 443        /* Get number of RPM/ctrl_val pairs in speed map */
 444        prop = of_find_property(np, "gpio-fan,speed-map", &i);
 445        if (!prop) {
 446                dev_err(dev, "gpio-fan,speed-map DT property missing");
 447                return -ENODEV;
 448        }
 449        i = i / sizeof(u32);
 450        if (i == 0 || i & 1) {
 451                dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
 452                return -ENODEV;
 453        }
 454        fan_data->num_speed = i / 2;
 455
 456        /*
 457         * Populate speed map
 458         * Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
 459         * this needs splitting into pairs to create gpio_fan_speed structs
 460         */
 461        speed = devm_kcalloc(dev,
 462                        fan_data->num_speed, sizeof(struct gpio_fan_speed),
 463                        GFP_KERNEL);
 464        if (!speed)
 465                return -ENOMEM;
 466        p = NULL;
 467        for (i = 0; i < fan_data->num_speed; i++) {
 468                p = of_prop_next_u32(prop, p, &u);
 469                if (!p)
 470                        return -ENODEV;
 471                speed[i].rpm = u;
 472                p = of_prop_next_u32(prop, p, &u);
 473                if (!p)
 474                        return -ENODEV;
 475                speed[i].ctrl_val = u;
 476        }
 477        fan_data->speed = speed;
 478
 479        return 0;
 480}
 481
 482static const struct of_device_id of_gpio_fan_match[] = {
 483        { .compatible = "gpio-fan", },
 484        {},
 485};
 486MODULE_DEVICE_TABLE(of, of_gpio_fan_match);
 487
 488static void gpio_fan_stop(void *data)
 489{
 490        set_fan_speed(data, 0);
 491}
 492
 493static int gpio_fan_probe(struct platform_device *pdev)
 494{
 495        int err;
 496        struct gpio_fan_data *fan_data;
 497        struct device *dev = &pdev->dev;
 498        struct device_node *np = dev->of_node;
 499
 500        fan_data = devm_kzalloc(dev, sizeof(struct gpio_fan_data),
 501                                GFP_KERNEL);
 502        if (!fan_data)
 503                return -ENOMEM;
 504
 505        fan_data->dev = dev;
 506        err = gpio_fan_get_of_data(fan_data);
 507        if (err)
 508                return err;
 509
 510        platform_set_drvdata(pdev, fan_data);
 511        mutex_init(&fan_data->lock);
 512
 513        /* Configure control GPIOs if available. */
 514        if (fan_data->gpios && fan_data->num_gpios > 0) {
 515                if (!fan_data->speed || fan_data->num_speed <= 1)
 516                        return -EINVAL;
 517                err = fan_ctrl_init(fan_data);
 518                if (err)
 519                        return err;
 520                err = devm_add_action_or_reset(dev, gpio_fan_stop, fan_data);
 521                if (err)
 522                        return err;
 523        }
 524
 525        /* Make this driver part of hwmon class. */
 526        fan_data->hwmon_dev =
 527                devm_hwmon_device_register_with_groups(dev,
 528                                                       "gpio_fan", fan_data,
 529                                                       gpio_fan_groups);
 530        if (IS_ERR(fan_data->hwmon_dev))
 531                return PTR_ERR(fan_data->hwmon_dev);
 532
 533        /* Configure alarm GPIO if available. */
 534        if (fan_data->alarm_gpio) {
 535                err = fan_alarm_init(fan_data);
 536                if (err)
 537                        return err;
 538        }
 539
 540        /* Optional cooling device register for Device tree platforms */
 541        fan_data->cdev = devm_thermal_of_cooling_device_register(dev, np,
 542                                "gpio-fan", fan_data, &gpio_fan_cool_ops);
 543
 544        dev_info(dev, "GPIO fan initialized\n");
 545
 546        return 0;
 547}
 548
 549static void gpio_fan_shutdown(struct platform_device *pdev)
 550{
 551        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
 552
 553        if (fan_data->gpios)
 554                set_fan_speed(fan_data, 0);
 555}
 556
 557#ifdef CONFIG_PM_SLEEP
 558static int gpio_fan_suspend(struct device *dev)
 559{
 560        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 561
 562        if (fan_data->gpios) {
 563                fan_data->resume_speed = fan_data->speed_index;
 564                set_fan_speed(fan_data, 0);
 565        }
 566
 567        return 0;
 568}
 569
 570static int gpio_fan_resume(struct device *dev)
 571{
 572        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 573
 574        if (fan_data->gpios)
 575                set_fan_speed(fan_data, fan_data->resume_speed);
 576
 577        return 0;
 578}
 579
 580static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
 581#define GPIO_FAN_PM     (&gpio_fan_pm)
 582#else
 583#define GPIO_FAN_PM     NULL
 584#endif
 585
 586static struct platform_driver gpio_fan_driver = {
 587        .probe          = gpio_fan_probe,
 588        .shutdown       = gpio_fan_shutdown,
 589        .driver = {
 590                .name   = "gpio-fan",
 591                .pm     = GPIO_FAN_PM,
 592                .of_match_table = of_match_ptr(of_gpio_fan_match),
 593        },
 594};
 595
 596module_platform_driver(gpio_fan_driver);
 597
 598MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
 599MODULE_DESCRIPTION("GPIO FAN driver");
 600MODULE_LICENSE("GPL");
 601MODULE_ALIAS("platform:gpio-fan");
 602