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