1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * pwm-fan.c - Hwmon driver for fans connected to PWM lines. 4 * 5 * Copyright (c) 2014 Samsung Electronics Co., Ltd. 6 * 7 * Author: Kamil Debski <k.debski@samsung.com> 8 */ 9 10 #include <linux/hwmon.h> 11 #include <linux/interrupt.h> 12 #include <linux/module.h> 13 #include <linux/mutex.h> 14 #include <linux/of.h> 15 #include <linux/platform_device.h> 16 #include <linux/pwm.h> 17 #include <linux/regulator/consumer.h> 18 #include <linux/sysfs.h> 19 #include <linux/thermal.h> 20 #include <linux/timer.h> 21 22 #define MAX_PWM 255 23 24 struct pwm_fan_tach { 25 int irq; 26 atomic_t pulses; 27 unsigned int rpm; 28 u8 pulses_per_revolution; 29 }; 30 31 struct pwm_fan_ctx { 32 struct mutex lock; 33 struct pwm_device *pwm; 34 struct pwm_state pwm_state; 35 struct regulator *reg_en; 36 37 int tach_count; 38 struct pwm_fan_tach *tachs; 39 ktime_t sample_start; 40 struct timer_list rpm_timer; 41 42 unsigned int pwm_value; 43 unsigned int pwm_fan_state; 44 unsigned int pwm_fan_max_state; 45 unsigned int *pwm_fan_cooling_levels; 46 struct thermal_cooling_device *cdev; 47 48 struct hwmon_chip_info info; 49 struct hwmon_channel_info fan_channel; 50 }; 51 52 static const u32 pwm_fan_channel_config_pwm[] = { 53 HWMON_PWM_INPUT, 54 0 55 }; 56 57 static const struct hwmon_channel_info pwm_fan_channel_pwm = { 58 .type = hwmon_pwm, 59 .config = pwm_fan_channel_config_pwm, 60 }; 61 62 /* This handler assumes self resetting edge triggered interrupt. */ 63 static irqreturn_t pulse_handler(int irq, void *dev_id) 64 { 65 struct pwm_fan_tach *tach = dev_id; 66 67 atomic_inc(&tach->pulses); 68 69 return IRQ_HANDLED; 70 } 71 72 static void sample_timer(struct timer_list *t) 73 { 74 struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer); 75 unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start); 76 int i; 77 78 if (delta) { 79 for (i = 0; i < ctx->tach_count; i++) { 80 struct pwm_fan_tach *tach = &ctx->tachs[i]; 81 int pulses; 82 83 pulses = atomic_read(&tach->pulses); 84 atomic_sub(pulses, &tach->pulses); 85 tach->rpm = (unsigned int)(pulses * 1000 * 60) / 86 (tach->pulses_per_revolution * delta); 87 } 88 89 ctx->sample_start = ktime_get(); 90 } 91 92 mod_timer(&ctx->rpm_timer, jiffies + HZ); 93 } 94 95 static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) 96 { 97 unsigned long period; 98 int ret = 0; 99 struct pwm_state *state = &ctx->pwm_state; 100 101 mutex_lock(&ctx->lock); 102 if (ctx->pwm_value == pwm) 103 goto exit_set_pwm_err; 104 105 period = state->period; 106 state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM); 107 state->enabled = pwm ? true : false; 108 109 ret = pwm_apply_state(ctx->pwm, state); 110 if (!ret) 111 ctx->pwm_value = pwm; 112 exit_set_pwm_err: 113 mutex_unlock(&ctx->lock); 114 return ret; 115 } 116 117 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm) 118 { 119 int i; 120 121 for (i = 0; i < ctx->pwm_fan_max_state; ++i) 122 if (pwm < ctx->pwm_fan_cooling_levels[i + 1]) 123 break; 124 125 ctx->pwm_fan_state = i; 126 } 127 128 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type, 129 u32 attr, int channel, long val) 130 { 131 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); 132 int ret; 133 134 if (val < 0 || val > MAX_PWM) 135 return -EINVAL; 136 137 ret = __set_pwm(ctx, val); 138 if (ret) 139 return ret; 140 141 pwm_fan_update_state(ctx, val); 142 return 0; 143 } 144 145 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type, 146 u32 attr, int channel, long *val) 147 { 148 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); 149 150 switch (type) { 151 case hwmon_pwm: 152 *val = ctx->pwm_value; 153 return 0; 154 155 case hwmon_fan: 156 *val = ctx->tachs[channel].rpm; 157 return 0; 158 159 default: 160 return -ENOTSUPP; 161 } 162 } 163 164 static umode_t pwm_fan_is_visible(const void *data, 165 enum hwmon_sensor_types type, 166 u32 attr, int channel) 167 { 168 switch (type) { 169 case hwmon_pwm: 170 return 0644; 171 172 case hwmon_fan: 173 return 0444; 174 175 default: 176 return 0; 177 } 178 } 179 180 static const struct hwmon_ops pwm_fan_hwmon_ops = { 181 .is_visible = pwm_fan_is_visible, 182 .read = pwm_fan_read, 183 .write = pwm_fan_write, 184 }; 185 186 /* thermal cooling device callbacks */ 187 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev, 188 unsigned long *state) 189 { 190 struct pwm_fan_ctx *ctx = cdev->devdata; 191 192 if (!ctx) 193 return -EINVAL; 194 195 *state = ctx->pwm_fan_max_state; 196 197 return 0; 198 } 199 200 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev, 201 unsigned long *state) 202 { 203 struct pwm_fan_ctx *ctx = cdev->devdata; 204 205 if (!ctx) 206 return -EINVAL; 207 208 *state = ctx->pwm_fan_state; 209 210 return 0; 211 } 212 213 static int 214 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state) 215 { 216 struct pwm_fan_ctx *ctx = cdev->devdata; 217 int ret; 218 219 if (!ctx || (state > ctx->pwm_fan_max_state)) 220 return -EINVAL; 221 222 if (state == ctx->pwm_fan_state) 223 return 0; 224 225 ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]); 226 if (ret) { 227 dev_err(&cdev->device, "Cannot set pwm!\n"); 228 return ret; 229 } 230 231 ctx->pwm_fan_state = state; 232 233 return ret; 234 } 235 236 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = { 237 .get_max_state = pwm_fan_get_max_state, 238 .get_cur_state = pwm_fan_get_cur_state, 239 .set_cur_state = pwm_fan_set_cur_state, 240 }; 241 242 static int pwm_fan_of_get_cooling_data(struct device *dev, 243 struct pwm_fan_ctx *ctx) 244 { 245 struct device_node *np = dev->of_node; 246 int num, i, ret; 247 248 if (!of_find_property(np, "cooling-levels", NULL)) 249 return 0; 250 251 ret = of_property_count_u32_elems(np, "cooling-levels"); 252 if (ret <= 0) { 253 dev_err(dev, "Wrong data!\n"); 254 return ret ? : -EINVAL; 255 } 256 257 num = ret; 258 ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32), 259 GFP_KERNEL); 260 if (!ctx->pwm_fan_cooling_levels) 261 return -ENOMEM; 262 263 ret = of_property_read_u32_array(np, "cooling-levels", 264 ctx->pwm_fan_cooling_levels, num); 265 if (ret) { 266 dev_err(dev, "Property 'cooling-levels' cannot be read!\n"); 267 return ret; 268 } 269 270 for (i = 0; i < num; i++) { 271 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) { 272 dev_err(dev, "PWM fan state[%d]:%d > %d\n", i, 273 ctx->pwm_fan_cooling_levels[i], MAX_PWM); 274 return -EINVAL; 275 } 276 } 277 278 ctx->pwm_fan_max_state = num - 1; 279 280 return 0; 281 } 282 283 static void pwm_fan_regulator_disable(void *data) 284 { 285 regulator_disable(data); 286 } 287 288 static void pwm_fan_pwm_disable(void *__ctx) 289 { 290 struct pwm_fan_ctx *ctx = __ctx; 291 292 ctx->pwm_state.enabled = false; 293 pwm_apply_state(ctx->pwm, &ctx->pwm_state); 294 del_timer_sync(&ctx->rpm_timer); 295 } 296 297 static int pwm_fan_probe(struct platform_device *pdev) 298 { 299 struct thermal_cooling_device *cdev; 300 struct device *dev = &pdev->dev; 301 struct pwm_fan_ctx *ctx; 302 struct device *hwmon; 303 int ret; 304 const struct hwmon_channel_info **channels; 305 u32 *fan_channel_config; 306 int channel_count = 1; /* We always have a PWM channel. */ 307 int i; 308 309 ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL); 310 if (!ctx) 311 return -ENOMEM; 312 313 mutex_init(&ctx->lock); 314 315 ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL); 316 if (IS_ERR(ctx->pwm)) 317 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n"); 318 319 platform_set_drvdata(pdev, ctx); 320 321 ctx->reg_en = devm_regulator_get_optional(dev, "fan"); 322 if (IS_ERR(ctx->reg_en)) { 323 if (PTR_ERR(ctx->reg_en) != -ENODEV) 324 return PTR_ERR(ctx->reg_en); 325 326 ctx->reg_en = NULL; 327 } else { 328 ret = regulator_enable(ctx->reg_en); 329 if (ret) { 330 dev_err(dev, "Failed to enable fan supply: %d\n", ret); 331 return ret; 332 } 333 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable, 334 ctx->reg_en); 335 if (ret) 336 return ret; 337 } 338 339 pwm_init_state(ctx->pwm, &ctx->pwm_state); 340 341 /* 342 * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned 343 * long. Check this here to prevent the fan running at a too low 344 * frequency. 345 */ 346 if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) { 347 dev_err(dev, "Configured period too big\n"); 348 return -EINVAL; 349 } 350 351 /* Set duty cycle to maximum allowed and enable PWM output */ 352 ret = __set_pwm(ctx, MAX_PWM); 353 if (ret) { 354 dev_err(dev, "Failed to configure PWM: %d\n", ret); 355 return ret; 356 } 357 timer_setup(&ctx->rpm_timer, sample_timer, 0); 358 ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx); 359 if (ret) 360 return ret; 361 362 ctx->tach_count = platform_irq_count(pdev); 363 if (ctx->tach_count < 0) 364 return dev_err_probe(dev, ctx->tach_count, 365 "Could not get number of fan tachometer inputs\n"); 366 dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count); 367 368 if (ctx->tach_count) { 369 channel_count++; /* We also have a FAN channel. */ 370 371 ctx->tachs = devm_kcalloc(dev, ctx->tach_count, 372 sizeof(struct pwm_fan_tach), 373 GFP_KERNEL); 374 if (!ctx->tachs) 375 return -ENOMEM; 376 377 ctx->fan_channel.type = hwmon_fan; 378 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1, 379 sizeof(u32), GFP_KERNEL); 380 if (!fan_channel_config) 381 return -ENOMEM; 382 ctx->fan_channel.config = fan_channel_config; 383 } 384 385 channels = devm_kcalloc(dev, channel_count + 1, 386 sizeof(struct hwmon_channel_info *), GFP_KERNEL); 387 if (!channels) 388 return -ENOMEM; 389 390 channels[0] = &pwm_fan_channel_pwm; 391 392 for (i = 0; i < ctx->tach_count; i++) { 393 struct pwm_fan_tach *tach = &ctx->tachs[i]; 394 u32 ppr = 2; 395 396 tach->irq = platform_get_irq(pdev, i); 397 if (tach->irq == -EPROBE_DEFER) 398 return tach->irq; 399 if (tach->irq > 0) { 400 ret = devm_request_irq(dev, tach->irq, pulse_handler, 0, 401 pdev->name, tach); 402 if (ret) { 403 dev_err(dev, 404 "Failed to request interrupt: %d\n", 405 ret); 406 return ret; 407 } 408 } 409 410 of_property_read_u32_index(dev->of_node, 411 "pulses-per-revolution", 412 i, 413 &ppr); 414 tach->pulses_per_revolution = ppr; 415 if (!tach->pulses_per_revolution) { 416 dev_err(dev, "pulses-per-revolution can't be zero.\n"); 417 return -EINVAL; 418 } 419 420 fan_channel_config[i] = HWMON_F_INPUT; 421 422 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n", 423 i, tach->irq, tach->pulses_per_revolution); 424 } 425 426 if (ctx->tach_count > 0) { 427 ctx->sample_start = ktime_get(); 428 mod_timer(&ctx->rpm_timer, jiffies + HZ); 429 430 channels[1] = &ctx->fan_channel; 431 } 432 433 ctx->info.ops = &pwm_fan_hwmon_ops; 434 ctx->info.info = channels; 435 436 hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan", 437 ctx, &ctx->info, NULL); 438 if (IS_ERR(hwmon)) { 439 dev_err(dev, "Failed to register hwmon device\n"); 440 return PTR_ERR(hwmon); 441 } 442 443 ret = pwm_fan_of_get_cooling_data(dev, ctx); 444 if (ret) 445 return ret; 446 447 ctx->pwm_fan_state = ctx->pwm_fan_max_state; 448 if (IS_ENABLED(CONFIG_THERMAL)) { 449 cdev = devm_thermal_of_cooling_device_register(dev, 450 dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops); 451 if (IS_ERR(cdev)) { 452 ret = PTR_ERR(cdev); 453 dev_err(dev, 454 "Failed to register pwm-fan as cooling device: %d\n", 455 ret); 456 return ret; 457 } 458 ctx->cdev = cdev; 459 } 460 461 return 0; 462 } 463 464 static int pwm_fan_disable(struct device *dev) 465 { 466 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); 467 int ret; 468 469 if (ctx->pwm_value) { 470 /* keep ctx->pwm_state unmodified for pwm_fan_resume() */ 471 struct pwm_state state = ctx->pwm_state; 472 473 state.duty_cycle = 0; 474 state.enabled = false; 475 ret = pwm_apply_state(ctx->pwm, &state); 476 if (ret < 0) 477 return ret; 478 } 479 480 if (ctx->reg_en) { 481 ret = regulator_disable(ctx->reg_en); 482 if (ret) { 483 dev_err(dev, "Failed to disable fan supply: %d\n", ret); 484 return ret; 485 } 486 } 487 488 return 0; 489 } 490 491 static void pwm_fan_shutdown(struct platform_device *pdev) 492 { 493 pwm_fan_disable(&pdev->dev); 494 } 495 496 #ifdef CONFIG_PM_SLEEP 497 static int pwm_fan_suspend(struct device *dev) 498 { 499 return pwm_fan_disable(dev); 500 } 501 502 static int pwm_fan_resume(struct device *dev) 503 { 504 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); 505 int ret; 506 507 if (ctx->reg_en) { 508 ret = regulator_enable(ctx->reg_en); 509 if (ret) { 510 dev_err(dev, "Failed to enable fan supply: %d\n", ret); 511 return ret; 512 } 513 } 514 515 if (ctx->pwm_value == 0) 516 return 0; 517 518 return pwm_apply_state(ctx->pwm, &ctx->pwm_state); 519 } 520 #endif 521 522 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume); 523 524 static const struct of_device_id of_pwm_fan_match[] = { 525 { .compatible = "pwm-fan", }, 526 {}, 527 }; 528 MODULE_DEVICE_TABLE(of, of_pwm_fan_match); 529 530 static struct platform_driver pwm_fan_driver = { 531 .probe = pwm_fan_probe, 532 .shutdown = pwm_fan_shutdown, 533 .driver = { 534 .name = "pwm-fan", 535 .pm = &pwm_fan_pm, 536 .of_match_table = of_pwm_fan_match, 537 }, 538 }; 539 540 module_platform_driver(pwm_fan_driver); 541 542 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>"); 543 MODULE_ALIAS("platform:pwm-fan"); 544 MODULE_DESCRIPTION("PWM FAN driver"); 545 MODULE_LICENSE("GPL"); 546