xref: /linux/drivers/mmc/core/host.c (revision e814f3fd16acfb7f9966773953de8f740a1e3202)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/drivers/mmc/core/host.c
4  *
5  *  Copyright (C) 2003 Russell King, All Rights Reserved.
6  *  Copyright (C) 2007-2008 Pierre Ossman
7  *  Copyright (C) 2010 Linus Walleij
8  *
9  *  MMC host class device management
10  */
11 
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/idr.h>
15 #include <linux/of.h>
16 #include <linux/pagemap.h>
17 #include <linux/export.h>
18 #include <linux/leds.h>
19 #include <linux/slab.h>
20 
21 #include <linux/mmc/host.h>
22 #include <linux/mmc/card.h>
23 #include <linux/mmc/slot-gpio.h>
24 
25 #include "core.h"
26 #include "crypto.h"
27 #include "host.h"
28 #include "slot-gpio.h"
29 #include "pwrseq.h"
30 #include "sdio_ops.h"
31 
32 #define cls_dev_to_mmc_host(d)	container_of(d, struct mmc_host, class_dev)
33 
34 static DEFINE_IDA(mmc_host_ida);
35 
36 #ifdef CONFIG_PM_SLEEP
37 static int mmc_host_class_prepare(struct device *dev)
38 {
39 	struct mmc_host *host = cls_dev_to_mmc_host(dev);
40 
41 	/*
42 	 * It's safe to access the bus_ops pointer, as both userspace and the
43 	 * workqueue for detecting cards are frozen at this point.
44 	 */
45 	if (!host->bus_ops)
46 		return 0;
47 
48 	/* Validate conditions for system suspend. */
49 	if (host->bus_ops->pre_suspend)
50 		return host->bus_ops->pre_suspend(host);
51 
52 	return 0;
53 }
54 
55 static void mmc_host_class_complete(struct device *dev)
56 {
57 	struct mmc_host *host = cls_dev_to_mmc_host(dev);
58 
59 	_mmc_detect_change(host, 0, false);
60 }
61 
62 static const struct dev_pm_ops mmc_host_class_dev_pm_ops = {
63 	.prepare = mmc_host_class_prepare,
64 	.complete = mmc_host_class_complete,
65 };
66 
67 #define MMC_HOST_CLASS_DEV_PM_OPS (&mmc_host_class_dev_pm_ops)
68 #else
69 #define MMC_HOST_CLASS_DEV_PM_OPS NULL
70 #endif
71 
72 static void mmc_host_classdev_release(struct device *dev)
73 {
74 	struct mmc_host *host = cls_dev_to_mmc_host(dev);
75 	wakeup_source_unregister(host->ws);
76 	if (of_alias_get_id(host->parent->of_node, "mmc") < 0)
77 		ida_free(&mmc_host_ida, host->index);
78 	kfree(host);
79 }
80 
81 static int mmc_host_classdev_shutdown(struct device *dev)
82 {
83 	struct mmc_host *host = cls_dev_to_mmc_host(dev);
84 
85 	__mmc_stop_host(host);
86 	return 0;
87 }
88 
89 static const struct class mmc_host_class = {
90 	.name		= "mmc_host",
91 	.dev_release	= mmc_host_classdev_release,
92 	.shutdown_pre	= mmc_host_classdev_shutdown,
93 	.pm		= MMC_HOST_CLASS_DEV_PM_OPS,
94 };
95 
96 int mmc_register_host_class(void)
97 {
98 	return class_register(&mmc_host_class);
99 }
100 
101 void mmc_unregister_host_class(void)
102 {
103 	class_unregister(&mmc_host_class);
104 }
105 
106 /**
107  * mmc_retune_enable() - enter a transfer mode that requires retuning
108  * @host: host which should retune now
109  */
110 void mmc_retune_enable(struct mmc_host *host)
111 {
112 	host->can_retune = 1;
113 	if (host->retune_period)
114 		mod_timer(&host->retune_timer,
115 			  jiffies + host->retune_period * HZ);
116 }
117 
118 /*
119  * Pause re-tuning for a small set of operations.  The pause begins after the
120  * next command.
121  */
122 void mmc_retune_pause(struct mmc_host *host)
123 {
124 	if (!host->retune_paused) {
125 		host->retune_paused = 1;
126 		mmc_retune_hold(host);
127 	}
128 }
129 EXPORT_SYMBOL(mmc_retune_pause);
130 
131 void mmc_retune_unpause(struct mmc_host *host)
132 {
133 	if (host->retune_paused) {
134 		host->retune_paused = 0;
135 		mmc_retune_release(host);
136 	}
137 }
138 EXPORT_SYMBOL(mmc_retune_unpause);
139 
140 /**
141  * mmc_retune_disable() - exit a transfer mode that requires retuning
142  * @host: host which should not retune anymore
143  *
144  * It is not meant for temporarily preventing retuning!
145  */
146 void mmc_retune_disable(struct mmc_host *host)
147 {
148 	mmc_retune_unpause(host);
149 	host->can_retune = 0;
150 	del_timer_sync(&host->retune_timer);
151 	mmc_retune_clear(host);
152 }
153 
154 void mmc_retune_timer_stop(struct mmc_host *host)
155 {
156 	del_timer_sync(&host->retune_timer);
157 }
158 EXPORT_SYMBOL(mmc_retune_timer_stop);
159 
160 void mmc_retune_hold(struct mmc_host *host)
161 {
162 	if (!host->hold_retune)
163 		host->retune_now = 1;
164 	host->hold_retune += 1;
165 }
166 
167 void mmc_retune_release(struct mmc_host *host)
168 {
169 	if (host->hold_retune)
170 		host->hold_retune -= 1;
171 	else
172 		WARN_ON(1);
173 }
174 EXPORT_SYMBOL(mmc_retune_release);
175 
176 int mmc_retune(struct mmc_host *host)
177 {
178 	bool return_to_hs400 = false;
179 	int err;
180 
181 	if (host->retune_now)
182 		host->retune_now = 0;
183 	else
184 		return 0;
185 
186 	if (!host->need_retune || host->doing_retune || !host->card)
187 		return 0;
188 
189 	host->need_retune = 0;
190 
191 	host->doing_retune = 1;
192 
193 	if (host->ios.timing == MMC_TIMING_MMC_HS400) {
194 		err = mmc_hs400_to_hs200(host->card);
195 		if (err)
196 			goto out;
197 
198 		return_to_hs400 = true;
199 	}
200 
201 	err = mmc_execute_tuning(host->card);
202 	if (err)
203 		goto out;
204 
205 	if (return_to_hs400)
206 		err = mmc_hs200_to_hs400(host->card);
207 out:
208 	host->doing_retune = 0;
209 
210 	return err;
211 }
212 
213 static void mmc_retune_timer(struct timer_list *t)
214 {
215 	struct mmc_host *host = from_timer(host, t, retune_timer);
216 
217 	mmc_retune_needed(host);
218 }
219 
220 static void mmc_of_parse_timing_phase(struct device *dev, const char *prop,
221 				      struct mmc_clk_phase *phase)
222 {
223 	int degrees[2] = {0};
224 	int rc;
225 
226 	rc = device_property_read_u32_array(dev, prop, degrees, 2);
227 	phase->valid = !rc;
228 	if (phase->valid) {
229 		phase->in_deg = degrees[0];
230 		phase->out_deg = degrees[1];
231 	}
232 }
233 
234 void
235 mmc_of_parse_clk_phase(struct device *dev, struct mmc_clk_phase_map *map)
236 {
237 	mmc_of_parse_timing_phase(dev, "clk-phase-legacy",
238 				  &map->phase[MMC_TIMING_LEGACY]);
239 	mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs",
240 				  &map->phase[MMC_TIMING_MMC_HS]);
241 	mmc_of_parse_timing_phase(dev, "clk-phase-sd-hs",
242 				  &map->phase[MMC_TIMING_SD_HS]);
243 	mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr12",
244 				  &map->phase[MMC_TIMING_UHS_SDR12]);
245 	mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr25",
246 				  &map->phase[MMC_TIMING_UHS_SDR25]);
247 	mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr50",
248 				  &map->phase[MMC_TIMING_UHS_SDR50]);
249 	mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr104",
250 				  &map->phase[MMC_TIMING_UHS_SDR104]);
251 	mmc_of_parse_timing_phase(dev, "clk-phase-uhs-ddr50",
252 				  &map->phase[MMC_TIMING_UHS_DDR50]);
253 	mmc_of_parse_timing_phase(dev, "clk-phase-mmc-ddr52",
254 				  &map->phase[MMC_TIMING_MMC_DDR52]);
255 	mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs200",
256 				  &map->phase[MMC_TIMING_MMC_HS200]);
257 	mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs400",
258 				  &map->phase[MMC_TIMING_MMC_HS400]);
259 }
260 EXPORT_SYMBOL(mmc_of_parse_clk_phase);
261 
262 /**
263  * mmc_of_parse() - parse host's device properties
264  * @host: host whose properties should be parsed.
265  *
266  * To keep the rest of the MMC subsystem unaware of whether DT has been
267  * used to instantiate and configure this host instance or not, we
268  * parse the properties and set respective generic mmc-host flags and
269  * parameters.
270  */
271 int mmc_of_parse(struct mmc_host *host)
272 {
273 	struct device *dev = host->parent;
274 	u32 bus_width, drv_type, cd_debounce_delay_ms;
275 	int ret;
276 
277 	if (!dev || !dev_fwnode(dev))
278 		return 0;
279 
280 	/* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
281 	if (device_property_read_u32(dev, "bus-width", &bus_width) < 0) {
282 		dev_dbg(host->parent,
283 			"\"bus-width\" property is missing, assuming 1 bit.\n");
284 		bus_width = 1;
285 	}
286 
287 	switch (bus_width) {
288 	case 8:
289 		host->caps |= MMC_CAP_8_BIT_DATA;
290 		fallthrough;	/* Hosts capable of 8-bit can also do 4 bits */
291 	case 4:
292 		host->caps |= MMC_CAP_4_BIT_DATA;
293 		break;
294 	case 1:
295 		break;
296 	default:
297 		dev_err(host->parent,
298 			"Invalid \"bus-width\" value %u!\n", bus_width);
299 		return -EINVAL;
300 	}
301 
302 	/* f_max is obtained from the optional "max-frequency" property */
303 	device_property_read_u32(dev, "max-frequency", &host->f_max);
304 
305 	/*
306 	 * Configure CD and WP pins. They are both by default active low to
307 	 * match the SDHCI spec. If GPIOs are provided for CD and / or WP, the
308 	 * mmc-gpio helpers are used to attach, configure and use them. If
309 	 * polarity inversion is specified in DT, one of MMC_CAP2_CD_ACTIVE_HIGH
310 	 * and MMC_CAP2_RO_ACTIVE_HIGH capability-2 flags is set. If the
311 	 * "broken-cd" property is provided, the MMC_CAP_NEEDS_POLL capability
312 	 * is set. If the "non-removable" property is found, the
313 	 * MMC_CAP_NONREMOVABLE capability is set and no card-detection
314 	 * configuration is performed.
315 	 */
316 
317 	/* Parse Card Detection */
318 
319 	if (device_property_read_bool(dev, "non-removable")) {
320 		host->caps |= MMC_CAP_NONREMOVABLE;
321 	} else {
322 		if (device_property_read_bool(dev, "cd-inverted"))
323 			host->caps2 |= MMC_CAP2_CD_ACTIVE_HIGH;
324 
325 		if (device_property_read_u32(dev, "cd-debounce-delay-ms",
326 					     &cd_debounce_delay_ms))
327 			cd_debounce_delay_ms = 200;
328 
329 		if (device_property_read_bool(dev, "broken-cd"))
330 			host->caps |= MMC_CAP_NEEDS_POLL;
331 
332 		ret = mmc_gpiod_request_cd(host, "cd", 0, false,
333 					   cd_debounce_delay_ms * 1000);
334 		if (!ret)
335 			dev_info(host->parent, "Got CD GPIO\n");
336 		else if (ret != -ENOENT && ret != -ENOSYS)
337 			return ret;
338 	}
339 
340 	/* Parse Write Protection */
341 
342 	if (device_property_read_bool(dev, "wp-inverted"))
343 		host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
344 
345 	ret = mmc_gpiod_request_ro(host, "wp", 0, 0);
346 	if (!ret)
347 		dev_info(host->parent, "Got WP GPIO\n");
348 	else if (ret != -ENOENT && ret != -ENOSYS)
349 		return ret;
350 
351 	if (device_property_read_bool(dev, "disable-wp"))
352 		host->caps2 |= MMC_CAP2_NO_WRITE_PROTECT;
353 
354 	if (device_property_read_bool(dev, "cap-sd-highspeed"))
355 		host->caps |= MMC_CAP_SD_HIGHSPEED;
356 	if (device_property_read_bool(dev, "cap-mmc-highspeed"))
357 		host->caps |= MMC_CAP_MMC_HIGHSPEED;
358 	if (device_property_read_bool(dev, "sd-uhs-sdr12"))
359 		host->caps |= MMC_CAP_UHS_SDR12;
360 	if (device_property_read_bool(dev, "sd-uhs-sdr25"))
361 		host->caps |= MMC_CAP_UHS_SDR25;
362 	if (device_property_read_bool(dev, "sd-uhs-sdr50"))
363 		host->caps |= MMC_CAP_UHS_SDR50;
364 	if (device_property_read_bool(dev, "sd-uhs-sdr104"))
365 		host->caps |= MMC_CAP_UHS_SDR104;
366 	if (device_property_read_bool(dev, "sd-uhs-ddr50"))
367 		host->caps |= MMC_CAP_UHS_DDR50;
368 	if (device_property_read_bool(dev, "cap-power-off-card"))
369 		host->caps |= MMC_CAP_POWER_OFF_CARD;
370 	if (device_property_read_bool(dev, "cap-mmc-hw-reset"))
371 		host->caps |= MMC_CAP_HW_RESET;
372 	if (device_property_read_bool(dev, "cap-sdio-irq"))
373 		host->caps |= MMC_CAP_SDIO_IRQ;
374 	if (device_property_read_bool(dev, "full-pwr-cycle"))
375 		host->caps2 |= MMC_CAP2_FULL_PWR_CYCLE;
376 	if (device_property_read_bool(dev, "full-pwr-cycle-in-suspend"))
377 		host->caps2 |= MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND;
378 	if (device_property_read_bool(dev, "keep-power-in-suspend"))
379 		host->pm_caps |= MMC_PM_KEEP_POWER;
380 	if (device_property_read_bool(dev, "wakeup-source") ||
381 	    device_property_read_bool(dev, "enable-sdio-wakeup")) /* legacy */
382 		host->pm_caps |= MMC_PM_WAKE_SDIO_IRQ;
383 	if (device_property_read_bool(dev, "mmc-ddr-3_3v"))
384 		host->caps |= MMC_CAP_3_3V_DDR;
385 	if (device_property_read_bool(dev, "mmc-ddr-1_8v"))
386 		host->caps |= MMC_CAP_1_8V_DDR;
387 	if (device_property_read_bool(dev, "mmc-ddr-1_2v"))
388 		host->caps |= MMC_CAP_1_2V_DDR;
389 	if (device_property_read_bool(dev, "mmc-hs200-1_8v"))
390 		host->caps2 |= MMC_CAP2_HS200_1_8V_SDR;
391 	if (device_property_read_bool(dev, "mmc-hs200-1_2v"))
392 		host->caps2 |= MMC_CAP2_HS200_1_2V_SDR;
393 	if (device_property_read_bool(dev, "mmc-hs400-1_8v"))
394 		host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
395 	if (device_property_read_bool(dev, "mmc-hs400-1_2v"))
396 		host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
397 	if (device_property_read_bool(dev, "mmc-hs400-enhanced-strobe"))
398 		host->caps2 |= MMC_CAP2_HS400_ES;
399 	if (device_property_read_bool(dev, "no-sdio"))
400 		host->caps2 |= MMC_CAP2_NO_SDIO;
401 	if (device_property_read_bool(dev, "no-sd"))
402 		host->caps2 |= MMC_CAP2_NO_SD;
403 	if (device_property_read_bool(dev, "no-mmc"))
404 		host->caps2 |= MMC_CAP2_NO_MMC;
405 	if (device_property_read_bool(dev, "no-mmc-hs400"))
406 		host->caps2 &= ~(MMC_CAP2_HS400_1_8V | MMC_CAP2_HS400_1_2V |
407 				 MMC_CAP2_HS400_ES);
408 
409 	/* Must be after "non-removable" check */
410 	if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) {
411 		if (host->caps & MMC_CAP_NONREMOVABLE)
412 			host->fixed_drv_type = drv_type;
413 		else
414 			dev_err(host->parent,
415 				"can't use fixed driver type, media is removable\n");
416 	}
417 
418 	host->dsr_req = !device_property_read_u32(dev, "dsr", &host->dsr);
419 	if (host->dsr_req && (host->dsr & ~0xffff)) {
420 		dev_err(host->parent,
421 			"device tree specified broken value for DSR: 0x%x, ignoring\n",
422 			host->dsr);
423 		host->dsr_req = 0;
424 	}
425 
426 	device_property_read_u32(dev, "post-power-on-delay-ms",
427 				 &host->ios.power_delay_ms);
428 
429 	return mmc_pwrseq_alloc(host);
430 }
431 
432 EXPORT_SYMBOL(mmc_of_parse);
433 
434 /**
435  * mmc_of_parse_voltage - return mask of supported voltages
436  * @host: host whose properties should be parsed.
437  * @mask: mask of voltages available for MMC/SD/SDIO
438  *
439  * Parse the "voltage-ranges" property, returning zero if it is not
440  * found, negative errno if the voltage-range specification is invalid,
441  * or one if the voltage-range is specified and successfully parsed.
442  */
443 int mmc_of_parse_voltage(struct mmc_host *host, u32 *mask)
444 {
445 	const char *prop = "voltage-ranges";
446 	struct device *dev = host->parent;
447 	u32 *voltage_ranges;
448 	int num_ranges, i;
449 	int ret;
450 
451 	if (!device_property_present(dev, prop)) {
452 		dev_dbg(dev, "%s unspecified\n", prop);
453 		return 0;
454 	}
455 
456 	ret = device_property_count_u32(dev, prop);
457 	if (ret < 0)
458 		return ret;
459 
460 	num_ranges = ret / 2;
461 	if (!num_ranges) {
462 		dev_err(dev, "%s empty\n", prop);
463 		return -EINVAL;
464 	}
465 
466 	voltage_ranges = kcalloc(2 * num_ranges, sizeof(*voltage_ranges), GFP_KERNEL);
467 	if (!voltage_ranges)
468 		return -ENOMEM;
469 
470 	ret = device_property_read_u32_array(dev, prop, voltage_ranges, 2 * num_ranges);
471 	if (ret) {
472 		kfree(voltage_ranges);
473 		return ret;
474 	}
475 
476 	for (i = 0; i < num_ranges; i++) {
477 		const int j = i * 2;
478 		u32 ocr_mask;
479 
480 		ocr_mask = mmc_vddrange_to_ocrmask(voltage_ranges[j + 0],
481 						   voltage_ranges[j + 1]);
482 		if (!ocr_mask) {
483 			dev_err(dev, "range #%d in %s is invalid\n", i, prop);
484 			kfree(voltage_ranges);
485 			return -EINVAL;
486 		}
487 		*mask |= ocr_mask;
488 	}
489 
490 	kfree(voltage_ranges);
491 
492 	return 1;
493 }
494 EXPORT_SYMBOL(mmc_of_parse_voltage);
495 
496 /**
497  * mmc_first_nonreserved_index() - get the first index that is not reserved
498  */
499 static int mmc_first_nonreserved_index(void)
500 {
501 	int max;
502 
503 	max = of_alias_get_highest_id("mmc");
504 	if (max < 0)
505 		return 0;
506 
507 	return max + 1;
508 }
509 
510 /**
511  *	mmc_alloc_host - initialise the per-host structure.
512  *	@extra: sizeof private data structure
513  *	@dev: pointer to host device model structure
514  *
515  *	Initialise the per-host structure.
516  */
517 struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
518 {
519 	int index;
520 	struct mmc_host *host;
521 	int alias_id, min_idx, max_idx;
522 
523 	host = kzalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
524 	if (!host)
525 		return NULL;
526 
527 	/* scanning will be enabled when we're ready */
528 	host->rescan_disable = 1;
529 
530 	alias_id = of_alias_get_id(dev->of_node, "mmc");
531 	if (alias_id >= 0) {
532 		index = alias_id;
533 	} else {
534 		min_idx = mmc_first_nonreserved_index();
535 		max_idx = 0;
536 
537 		index = ida_alloc_range(&mmc_host_ida, min_idx, max_idx - 1,
538 					GFP_KERNEL);
539 		if (index < 0) {
540 			kfree(host);
541 			return NULL;
542 		}
543 	}
544 
545 	host->index = index;
546 
547 	dev_set_name(&host->class_dev, "mmc%d", host->index);
548 	host->ws = wakeup_source_register(NULL, dev_name(&host->class_dev));
549 
550 	host->parent = dev;
551 	host->class_dev.parent = dev;
552 	host->class_dev.class = &mmc_host_class;
553 	device_initialize(&host->class_dev);
554 	device_enable_async_suspend(&host->class_dev);
555 
556 	if (mmc_gpio_alloc(host)) {
557 		put_device(&host->class_dev);
558 		return NULL;
559 	}
560 
561 	spin_lock_init(&host->lock);
562 	init_waitqueue_head(&host->wq);
563 	INIT_DELAYED_WORK(&host->detect, mmc_rescan);
564 	INIT_WORK(&host->sdio_irq_work, sdio_irq_work);
565 	timer_setup(&host->retune_timer, mmc_retune_timer, 0);
566 
567 	/*
568 	 * By default, hosts do not support SGIO or large requests.
569 	 * They have to set these according to their abilities.
570 	 */
571 	host->max_segs = 1;
572 	host->max_seg_size = PAGE_SIZE;
573 
574 	host->max_req_size = PAGE_SIZE;
575 	host->max_blk_size = 512;
576 	host->max_blk_count = PAGE_SIZE / 512;
577 
578 	host->fixed_drv_type = -EINVAL;
579 	host->ios.power_delay_ms = 10;
580 	host->ios.power_mode = MMC_POWER_UNDEFINED;
581 
582 	return host;
583 }
584 
585 EXPORT_SYMBOL(mmc_alloc_host);
586 
587 static void devm_mmc_host_release(struct device *dev, void *res)
588 {
589 	mmc_free_host(*(struct mmc_host **)res);
590 }
591 
592 struct mmc_host *devm_mmc_alloc_host(struct device *dev, int extra)
593 {
594 	struct mmc_host **dr, *host;
595 
596 	dr = devres_alloc(devm_mmc_host_release, sizeof(*dr), GFP_KERNEL);
597 	if (!dr)
598 		return NULL;
599 
600 	host = mmc_alloc_host(extra, dev);
601 	if (!host) {
602 		devres_free(dr);
603 		return NULL;
604 	}
605 
606 	*dr = host;
607 	devres_add(dev, dr);
608 
609 	return host;
610 }
611 EXPORT_SYMBOL(devm_mmc_alloc_host);
612 
613 static int mmc_validate_host_caps(struct mmc_host *host)
614 {
615 	struct device *dev = host->parent;
616 	u32 caps = host->caps, caps2 = host->caps2;
617 
618 	if (caps & MMC_CAP_SDIO_IRQ && !host->ops->enable_sdio_irq) {
619 		dev_warn(dev, "missing ->enable_sdio_irq() ops\n");
620 		return -EINVAL;
621 	}
622 
623 	if (caps2 & (MMC_CAP2_HS400_ES | MMC_CAP2_HS400) &&
624 	    !(caps & MMC_CAP_8_BIT_DATA) && !(caps2 & MMC_CAP2_NO_MMC)) {
625 		dev_warn(dev, "drop HS400 support since no 8-bit bus\n");
626 		host->caps2 = caps2 & ~MMC_CAP2_HS400_ES & ~MMC_CAP2_HS400;
627 	}
628 
629 	return 0;
630 }
631 
632 /**
633  *	mmc_add_host - initialise host hardware
634  *	@host: mmc host
635  *
636  *	Register the host with the driver model. The host must be
637  *	prepared to start servicing requests before this function
638  *	completes.
639  */
640 int mmc_add_host(struct mmc_host *host)
641 {
642 	int err;
643 
644 	err = mmc_validate_host_caps(host);
645 	if (err)
646 		return err;
647 
648 	err = device_add(&host->class_dev);
649 	if (err)
650 		return err;
651 
652 	led_trigger_register_simple(dev_name(&host->class_dev), &host->led);
653 
654 	mmc_add_host_debugfs(host);
655 
656 	mmc_start_host(host);
657 	return 0;
658 }
659 
660 EXPORT_SYMBOL(mmc_add_host);
661 
662 /**
663  *	mmc_remove_host - remove host hardware
664  *	@host: mmc host
665  *
666  *	Unregister and remove all cards associated with this host,
667  *	and power down the MMC bus. No new requests will be issued
668  *	after this function has returned.
669  */
670 void mmc_remove_host(struct mmc_host *host)
671 {
672 	mmc_stop_host(host);
673 
674 	mmc_remove_host_debugfs(host);
675 
676 	device_del(&host->class_dev);
677 
678 	led_trigger_unregister_simple(host->led);
679 }
680 
681 EXPORT_SYMBOL(mmc_remove_host);
682 
683 /**
684  *	mmc_free_host - free the host structure
685  *	@host: mmc host
686  *
687  *	Free the host once all references to it have been dropped.
688  */
689 void mmc_free_host(struct mmc_host *host)
690 {
691 	cancel_delayed_work_sync(&host->detect);
692 	mmc_pwrseq_free(host);
693 	put_device(&host->class_dev);
694 }
695 
696 EXPORT_SYMBOL(mmc_free_host);
697