[deliverable/linux.git] / drivers / mmc / core / host.c

/*
 *  linux/drivers/mmc/core/host.c
 *
 *  Copyright (C) 2003 Russell King, All Rights Reserved.
 *  Copyright (C) 2007-2008 Pierre Ossman
 *  Copyright (C) 2010 Linus Walleij
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  MMC host class device management
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/idr.h>
#include <linux/pagemap.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/suspend.h>

#include <linux/mmc/host.h>
#include <linux/mmc/card.h>

#include "core.h"
#include "host.h"

#define cls_dev_to_mmc_host(d)	container_of(d, struct mmc_host, class_dev)

static void mmc_host_classdev_release(struct device *dev)
{
	struct mmc_host *host = cls_dev_to_mmc_host(dev);
	kfree(host);
}

static struct class mmc_host_class = {
	.name		= "mmc_host",
	.dev_release	= mmc_host_classdev_release,
};

int mmc_register_host_class(void)
{
	return class_register(&mmc_host_class);
}

void mmc_unregister_host_class(void)
{
	class_unregister(&mmc_host_class);
}

static DEFINE_IDR(mmc_host_idr);
static DEFINE_SPINLOCK(mmc_host_lock);

#ifdef CONFIG_MMC_CLKGATE

/*
 * Enabling clock gating will make the core call out to the host
 * once up and once down when it performs a request or card operation
 * intermingled in any fashion. The driver will see this through
 * set_ios() operations with ios.clock field set to 0 to gate (disable)
 * the block clock, and to the old frequency to enable it again.
 */
static void mmc_host_clk_gate_delayed(struct mmc_host *host)
{
	unsigned long tick_ns;
	unsigned long freq = host->ios.clock;
	unsigned long flags;

	if (!freq) {
		pr_debug("%s: frequency set to 0 in disable function, "
			 "this means the clock is already disabled.\n",
			 mmc_hostname(host));
		return;
	}
	/*
	 * New requests may have appeared while we were scheduling,
	 * then there is no reason to delay the check before
	 * clk_disable().
	 */
	spin_lock_irqsave(&host->clk_lock, flags);

	/*
	 * Delay n bus cycles (at least 8 from MMC spec) before attempting
	 * to disable the MCI block clock. The reference count may have
	 * gone up again after this delay due to rescheduling!
	 */
	if (!host->clk_requests) {
		spin_unlock_irqrestore(&host->clk_lock, flags);
		tick_ns = DIV_ROUND_UP(1000000000, freq);
		ndelay(host->clk_delay * tick_ns);
	} else {
		/* New users appeared while waiting for this work */
		spin_unlock_irqrestore(&host->clk_lock, flags);
		return;
	}
	mutex_lock(&host->clk_gate_mutex);
	spin_lock_irqsave(&host->clk_lock, flags);
	if (!host->clk_requests) {
		spin_unlock_irqrestore(&host->clk_lock, flags);
		/* This will set host->ios.clock to 0 */
		mmc_gate_clock(host);
		spin_lock_irqsave(&host->clk_lock, flags);
		pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
	}
	spin_unlock_irqrestore(&host->clk_lock, flags);
	mutex_unlock(&host->clk_gate_mutex);
}

/*
 * Internal work. Work to disable the clock at some later point.
 */
static void mmc_host_clk_gate_work(struct work_struct *work)
{
	struct mmc_host *host = container_of(work, struct mmc_host,
					      clk_gate_work);

	mmc_host_clk_gate_delayed(host);
}

/**
 *	mmc_host_clk_ungate - ungate hardware MCI clocks
 *	@host: host to ungate.
 *
 *	Makes sure the host ios.clock is restored to a non-zero value
 *	past this call.	Increase clock reference count and ungate clock
 *	if we're the first user.
 */
void mmc_host_clk_ungate(struct mmc_host *host)
{
	unsigned long flags;

	mutex_lock(&host->clk_gate_mutex);
	spin_lock_irqsave(&host->clk_lock, flags);
	if (host->clk_gated) {
		spin_unlock_irqrestore(&host->clk_lock, flags);
		mmc_ungate_clock(host);
		spin_lock_irqsave(&host->clk_lock, flags);
		pr_debug("%s: ungated MCI clock\n", mmc_hostname(host));
	}
	host->clk_requests++;
	spin_unlock_irqrestore(&host->clk_lock, flags);
	mutex_unlock(&host->clk_gate_mutex);
}

/**
 *	mmc_host_may_gate_card - check if this card may be gated
 *	@card: card to check.
 */
static bool mmc_host_may_gate_card(struct mmc_card *card)
{
	/* If there is no card we may gate it */
	if (!card)
		return true;
	/*
	 * Don't gate SDIO cards! These need to be clocked at all times
	 * since they may be independent systems generating interrupts
	 * and other events. The clock requests counter from the core will
	 * go down to zero since the core does not need it, but we will not
	 * gate the clock, because there is somebody out there that may still
	 * be using it.
	 */
	if (mmc_card_sdio(card))
		return false;

	return true;
}

/**
 *	mmc_host_clk_gate - gate off hardware MCI clocks
 *	@host: host to gate.
 *
 *	Calls the host driver with ios.clock set to zero as often as possible
 *	in order to gate off hardware MCI clocks. Decrease clock reference
 *	count and schedule disabling of clock.
 */
void mmc_host_clk_gate(struct mmc_host *host)
{
	unsigned long flags;

	spin_lock_irqsave(&host->clk_lock, flags);
	host->clk_requests--;
	if (mmc_host_may_gate_card(host->card) &&
	    !host->clk_requests)
		schedule_work(&host->clk_gate_work);
	spin_unlock_irqrestore(&host->clk_lock, flags);
}

/**
 *	mmc_host_clk_rate - get current clock frequency setting
 *	@host: host to get the clock frequency for.
 *
 *	Returns current clock frequency regardless of gating.
 */
unsigned int mmc_host_clk_rate(struct mmc_host *host)
{
	unsigned long freq;
	unsigned long flags;

	spin_lock_irqsave(&host->clk_lock, flags);
	if (host->clk_gated)
		freq = host->clk_old;
	else
		freq = host->ios.clock;
	spin_unlock_irqrestore(&host->clk_lock, flags);
	return freq;
}

/**
 *	mmc_host_clk_init - set up clock gating code
 *	@host: host with potential clock to control
 */
static inline void mmc_host_clk_init(struct mmc_host *host)
{
	host->clk_requests = 0;
	/* Hold MCI clock for 8 cycles by default */
	host->clk_delay = 8;
	host->clk_gated = false;
	INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
	spin_lock_init(&host->clk_lock);
	mutex_init(&host->clk_gate_mutex);
}

/**
 *	mmc_host_clk_exit - shut down clock gating code
 *	@host: host with potential clock to control
 */
static inline void mmc_host_clk_exit(struct mmc_host *host)
{
	/*
	 * Wait for any outstanding gate and then make sure we're
	 * ungated before exiting.
	 */
	if (cancel_work_sync(&host->clk_gate_work))
		mmc_host_clk_gate_delayed(host);
	if (host->clk_gated)
		mmc_host_clk_ungate(host);
	/* There should be only one user now */
	WARN_ON(host->clk_requests > 1);
}

#else

static inline void mmc_host_clk_init(struct mmc_host *host)
{
}

static inline void mmc_host_clk_exit(struct mmc_host *host)
{
}

#endif

/**
 *	mmc_alloc_host - initialise the per-host structure.
 *	@extra: sizeof private data structure
 *	@dev: pointer to host device model structure
 *
 *	Initialise the per-host structure.
 */
struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
{
	int err;
	struct mmc_host *host;

	if (!idr_pre_get(&mmc_host_idr, GFP_KERNEL))
		return NULL;

	host = kzalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
	if (!host)
		return NULL;

	spin_lock(&mmc_host_lock);
	err = idr_get_new(&mmc_host_idr, host, &host->index);
	spin_unlock(&mmc_host_lock);
	if (err)
		goto free;

	dev_set_name(&host->class_dev, "mmc%d", host->index);

	host->parent = dev;
	host->class_dev.parent = dev;
	host->class_dev.class = &mmc_host_class;
	device_initialize(&host->class_dev);

	mmc_host_clk_init(host);

	spin_lock_init(&host->lock);
	init_waitqueue_head(&host->wq);
	INIT_DELAYED_WORK(&host->detect, mmc_rescan);
	INIT_DELAYED_WORK_DEFERRABLE(&host->disable, mmc_host_deeper_disable);
#ifdef CONFIG_PM
	host->pm_notify.notifier_call = mmc_pm_notify;
#endif

	/*
	 * By default, hosts do not support SGIO or large requests.
	 * They have to set these according to their abilities.
	 */
	host->max_segs = 1;
	host->max_seg_size = PAGE_CACHE_SIZE;

	host->max_req_size = PAGE_CACHE_SIZE;
	host->max_blk_size = 512;
	host->max_blk_count = PAGE_CACHE_SIZE / 512;

	return host;

free:
	kfree(host);
	return NULL;
}

EXPORT_SYMBOL(mmc_alloc_host);

/**
 *	mmc_add_host - initialise host hardware
 *	@host: mmc host
 *
 *	Register the host with the driver model. The host must be
 *	prepared to start servicing requests before this function
 *	completes.
 */
int mmc_add_host(struct mmc_host *host)
{
	int err;

	WARN_ON((host->caps & MMC_CAP_SDIO_IRQ) &&
		!host->ops->enable_sdio_irq);

	led_trigger_register_simple(dev_name(&host->class_dev), &host->led);

	err = device_add(&host->class_dev);
	if (err)
		return err;

#ifdef CONFIG_DEBUG_FS
	mmc_add_host_debugfs(host);
#endif

	mmc_start_host(host);
	register_pm_notifier(&host->pm_notify);

	return 0;
}

EXPORT_SYMBOL(mmc_add_host);

/**
 *	mmc_remove_host - remove host hardware
 *	@host: mmc host
 *
 *	Unregister and remove all cards associated with this host,
 *	and power down the MMC bus. No new requests will be issued
 *	after this function has returned.
 */
void mmc_remove_host(struct mmc_host *host)
{
	unregister_pm_notifier(&host->pm_notify);
	mmc_stop_host(host);

#ifdef CONFIG_DEBUG_FS
	mmc_remove_host_debugfs(host);
#endif

	device_del(&host->class_dev);

	led_trigger_unregister_simple(host->led);

	mmc_host_clk_exit(host);
}

EXPORT_SYMBOL(mmc_remove_host);

/**
 *	mmc_free_host - free the host structure
 *	@host: mmc host
 *
 *	Free the host once all references to it have been dropped.
 */
void mmc_free_host(struct mmc_host *host)
{
	spin_lock(&mmc_host_lock);
	idr_remove(&mmc_host_idr, host->index);
	spin_unlock(&mmc_host_lock);

	put_device(&host->class_dev);
}

EXPORT_SYMBOL(mmc_free_host);
Commit	Line	Data
b93931a6 PO	1	/*
	2	* linux/drivers/mmc/core/host.c
	3	*
	4	* Copyright (C) 2003 Russell King, All Rights Reserved.
ff3112f5	5	* Copyright (C) 2007-2008 Pierre Ossman
04566831	6	* Copyright (C) 2010 Linus Walleij
b93931a6 PO	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*
	12	* MMC host class device management
	13	*/
	14
	15	#include <linux/device.h>
	16	#include <linux/err.h>
	17	#include <linux/idr.h>
	18	#include <linux/pagemap.h>
af8350c7	19	#include <linux/leds.h>
5a0e3ad6	20	#include <linux/slab.h>
4c2ef25f	21	#include <linux/suspend.h>
b93931a6 PO	22
b93931a6 PO	23	#include <linux/mmc/host.h>
04566831	24	#include <linux/mmc/card.h>
b93931a6 PO	25
	26	#include "core.h"
	27	#include "host.h"
	28
	29	#define cls_dev_to_mmc_host(d) container_of(d, struct mmc_host, class_dev)
	30
	31	static void mmc_host_classdev_release(struct device *dev)
	32	{
	33	struct mmc_host *host = cls_dev_to_mmc_host(dev);
	34	kfree(host);
	35	}
	36
	37	static struct class mmc_host_class = {
	38	.name = "mmc_host",
	39	.dev_release = mmc_host_classdev_release,
	40	};
	41
	42	int mmc_register_host_class(void)
	43	{
	44	return class_register(&mmc_host_class);
	45	}
	46
	47	void mmc_unregister_host_class(void)
	48	{
	49	class_unregister(&mmc_host_class);
	50	}
	51
	52	static DEFINE_IDR(mmc_host_idr);
	53	static DEFINE_SPINLOCK(mmc_host_lock);
	54
04566831 LW	55	#ifdef CONFIG_MMC_CLKGATE
	56
	57	/*
	58	* Enabling clock gating will make the core call out to the host
	59	* once up and once down when it performs a request or card operation
	60	* intermingled in any fashion. The driver will see this through
	61	* set_ios() operations with ios.clock field set to 0 to gate (disable)
	62	* the block clock, and to the old frequency to enable it again.
	63	*/
	64	static void mmc_host_clk_gate_delayed(struct mmc_host *host)
	65	{
	66	unsigned long tick_ns;
	67	unsigned long freq = host->ios.clock;
	68	unsigned long flags;
	69
	70	if (!freq) {
	71	pr_debug("%s: frequency set to 0 in disable function, "
	72	"this means the clock is already disabled.\n",
	73	mmc_hostname(host));
	74	return;
	75	}
	76	/*
	77	* New requests may have appeared while we were scheduling,
	78	* then there is no reason to delay the check before
	79	* clk_disable().
	80	*/
	81	spin_lock_irqsave(&host->clk_lock, flags);
	82
	83	/*
	84	* Delay n bus cycles (at least 8 from MMC spec) before attempting
	85	* to disable the MCI block clock. The reference count may have
	86	* gone up again after this delay due to rescheduling!
	87	*/
	88	if (!host->clk_requests) {
	89	spin_unlock_irqrestore(&host->clk_lock, flags);
	90	tick_ns = DIV_ROUND_UP(1000000000, freq);
	91	ndelay(host->clk_delay * tick_ns);
	92	} else {
	93	/* New users appeared while waiting for this work */
	94	spin_unlock_irqrestore(&host->clk_lock, flags);
	95	return;
	96	}
	97	mutex_lock(&host->clk_gate_mutex);
	98	spin_lock_irqsave(&host->clk_lock, flags);
	99	if (!host->clk_requests) {
	100	spin_unlock_irqrestore(&host->clk_lock, flags);
	101	/* This will set host->ios.clock to 0 */
	102	mmc_gate_clock(host);
	103	spin_lock_irqsave(&host->clk_lock, flags);
	104	pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
	105	}
	106	spin_unlock_irqrestore(&host->clk_lock, flags);
	107	mutex_unlock(&host->clk_gate_mutex);
	108	}
	109
	110	/*
	111	* Internal work. Work to disable the clock at some later point.
	112	*/
	113	static void mmc_host_clk_gate_work(struct work_struct *work)
	114	{
	115	struct mmc_host *host = container_of(work, struct mmc_host,
	116	clk_gate_work);
	117
	118	mmc_host_clk_gate_delayed(host);
119	}
120
121	/**
122	* mmc_host_clk_ungate - ungate hardware MCI clocks
123	* @host: host to ungate.
124	*
125	* Makes sure the host ios.clock is restored to a non-zero value
126	* past this call. Increase clock reference count and ungate clock
127	* if we're the first user.
128	*/
129	void mmc_host_clk_ungate(struct mmc_host *host)
130	{
131	unsigned long flags;
132
133	mutex_lock(&host->clk_gate_mutex);
134	spin_lock_irqsave(&host->clk_lock, flags);
135	if (host->clk_gated) {
136	spin_unlock_irqrestore(&host->clk_lock, flags);
137	mmc_ungate_clock(host);
138	spin_lock_irqsave(&host->clk_lock, flags);
139	pr_debug("%s: ungated MCI clock\n", mmc_hostname(host));
140	}
141	host->clk_requests++;
142	spin_unlock_irqrestore(&host->clk_lock, flags);
143	mutex_unlock(&host->clk_gate_mutex);
144	}
145
146	/**
147	* mmc_host_may_gate_card - check if this card may be gated
148	* @card: card to check.
149	*/
150	static bool mmc_host_may_gate_card(struct mmc_card *card)
151	{
152	/* If there is no card we may gate it */
153	if (!card)
154	return true;
155	/*
156	* Don't gate SDIO cards! These need to be clocked at all times
157	* since they may be independent systems generating interrupts
158	* and other events. The clock requests counter from the core will
159	* go down to zero since the core does not need it, but we will not
160	* gate the clock, because there is somebody out there that may still
161	* be using it.
162	*/
163	if (mmc_card_sdio(card))
164	return false;
165
166	return true;
167	}
168
169	/**
170	* mmc_host_clk_gate - gate off hardware MCI clocks
171	* @host: host to gate.
172	*
173	* Calls the host driver with ios.clock set to zero as often as possible
174	* in order to gate off hardware MCI clocks. Decrease clock reference
175	* count and schedule disabling of clock.
176	*/
177	void mmc_host_clk_gate(struct mmc_host *host)
178	{
179	unsigned long flags;
180
181	spin_lock_irqsave(&host->clk_lock, flags);
182	host->clk_requests--;
183	if (mmc_host_may_gate_card(host->card) &&
184	!host->clk_requests)
185	schedule_work(&host->clk_gate_work);
186	spin_unlock_irqrestore(&host->clk_lock, flags);
187	}
188
189	/**
190	* mmc_host_clk_rate - get current clock frequency setting
191	* @host: host to get the clock frequency for.
192	*
193	* Returns current clock frequency regardless of gating.
194	*/
195	unsigned int mmc_host_clk_rate(struct mmc_host *host)
196	{
197	unsigned long freq;
198	unsigned long flags;
199
200	spin_lock_irqsave(&host->clk_lock, flags);
201	if (host->clk_gated)
202	freq = host->clk_old;
203	else
204	freq = host->ios.clock;
205	spin_unlock_irqrestore(&host->clk_lock, flags);
206	return freq;
207	}
208
209	/**
210	* mmc_host_clk_init - set up clock gating code
211	* @host: host with potential clock to control
212	*/
213	static inline void mmc_host_clk_init(struct mmc_host *host)
214	{
215	host->clk_requests = 0;
216	/* Hold MCI clock for 8 cycles by default */
217	host->clk_delay = 8;
218	host->clk_gated = false;
219	INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
220	spin_lock_init(&host->clk_lock);
221	mutex_init(&host->clk_gate_mutex);
222	}
223
224	/**
225	* mmc_host_clk_exit - shut down clock gating code
226	* @host: host with potential clock to control
227	*/
228	static inline void mmc_host_clk_exit(struct mmc_host *host)
229	{
230	/*
231	* Wait for any outstanding gate and then make sure we're
232	* ungated before exiting.
233	*/
234	if (cancel_work_sync(&host->clk_gate_work))
235	mmc_host_clk_gate_delayed(host);
236	if (host->clk_gated)
237	mmc_host_clk_ungate(host);
c288b855 LW	238	/* There should be only one user now */
c288b855 LW	239	WARN_ON(host->clk_requests > 1);
04566831 LW	240	}
	241
	242	#else
	243
	244	static inline void mmc_host_clk_init(struct mmc_host *host)
	245	{
	246	}
	247
	248	static inline void mmc_host_clk_exit(struct mmc_host *host)
	249	{
	250	}
	251
	252	#endif
	253
b93931a6 PO	254	/**
	255	* mmc_alloc_host - initialise the per-host structure.
	256	* @extra: sizeof private data structure
	257	* @dev: pointer to host device model structure
	258	*
	259	* Initialise the per-host structure.
	260	*/
	261	struct mmc_host mmc_alloc_host(int extra, struct device dev)
	262	{
ff3112f5	263	int err;
b93931a6 PO	264	struct mmc_host *host;
b93931a6 PO	265
ff3112f5 PO	266	if (!idr_pre_get(&mmc_host_idr, GFP_KERNEL))
	267	return NULL;
	268
be760a9d	269	host = kzalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
b93931a6 PO	270	if (!host)
	271	return NULL;
	272
ff3112f5 PO	273	spin_lock(&mmc_host_lock);
	274	err = idr_get_new(&mmc_host_idr, host, &host->index);
	275	spin_unlock(&mmc_host_lock);
	276	if (err)
	277	goto free;
	278
d1b26863	279	dev_set_name(&host->class_dev, "mmc%d", host->index);
ff3112f5	280
b93931a6 PO	281	host->parent = dev;
	282	host->class_dev.parent = dev;
	283	host->class_dev.class = &mmc_host_class;
	284	device_initialize(&host->class_dev);
	285
04566831 LW	286	mmc_host_clk_init(host);
04566831 LW	287
b93931a6 PO	288	spin_lock_init(&host->lock);
	289	init_waitqueue_head(&host->wq);
	290	INIT_DELAYED_WORK(&host->detect, mmc_rescan);
8ea926b2	291	INIT_DELAYED_WORK_DEFERRABLE(&host->disable, mmc_host_deeper_disable);
81ca03a0	292	#ifdef CONFIG_PM
4c2ef25f	293	host->pm_notify.notifier_call = mmc_pm_notify;
81ca03a0	294	#endif
b93931a6 PO	295
	296	/*
	297	* By default, hosts do not support SGIO or large requests.
	298	* They have to set these according to their abilities.
	299	*/
a36274e0	300	host->max_segs = 1;
b93931a6 PO	301	host->max_seg_size = PAGE_CACHE_SIZE;
	302
	303	host->max_req_size = PAGE_CACHE_SIZE;
	304	host->max_blk_size = 512;
	305	host->max_blk_count = PAGE_CACHE_SIZE / 512;
	306
	307	return host;
ff3112f5 PO	308
	309	free:
	310	kfree(host);
	311	return NULL;
b93931a6 PO	312	}
	313
	314	EXPORT_SYMBOL(mmc_alloc_host);
	315
	316	/**
	317	* mmc_add_host - initialise host hardware
	318	* @host: mmc host
67a61c48 PO	319	*
	320	* Register the host with the driver model. The host must be
	321	* prepared to start servicing requests before this function
	322	* completes.
b93931a6 PO	323	*/
	324	int mmc_add_host(struct mmc_host *host)
	325	{
	326	int err;
	327
17b759af NP	328	WARN_ON((host->caps & MMC_CAP_SDIO_IRQ) &&
	329	!host->ops->enable_sdio_irq);
	330
d1b26863	331	led_trigger_register_simple(dev_name(&host->class_dev), &host->led);
af8350c7	332
b93931a6 PO	333	err = device_add(&host->class_dev);
	334	if (err)
	335	return err;
	336
6edd8ee6 HS	337	#ifdef CONFIG_DEBUG_FS
	338	mmc_add_host_debugfs(host);
	339	#endif
	340
b93931a6	341	mmc_start_host(host);
4c2ef25f	342	register_pm_notifier(&host->pm_notify);
b93931a6 PO	343
	344	return 0;
	345	}
	346
	347	EXPORT_SYMBOL(mmc_add_host);
	348
	349	/**
	350	* mmc_remove_host - remove host hardware
	351	* @host: mmc host
	352	*
	353	* Unregister and remove all cards associated with this host,
67a61c48 PO	354	* and power down the MMC bus. No new requests will be issued
67a61c48 PO	355	* after this function has returned.
b93931a6 PO	356	*/
	357	void mmc_remove_host(struct mmc_host *host)
	358	{
4c2ef25f	359	unregister_pm_notifier(&host->pm_notify);
b93931a6 PO	360	mmc_stop_host(host);
b93931a6 PO	361
6edd8ee6 HS	362	#ifdef CONFIG_DEBUG_FS
	363	mmc_remove_host_debugfs(host);
	364	#endif
	365
b93931a6 PO	366	device_del(&host->class_dev);
b93931a6 PO	367
77f1fd6e	368	led_trigger_unregister_simple(host->led);
04566831 LW	369
04566831 LW	370	mmc_host_clk_exit(host);
b93931a6 PO	371	}
	372
	373	EXPORT_SYMBOL(mmc_remove_host);
	374
	375	/**
	376	* mmc_free_host - free the host structure
	377	* @host: mmc host
	378	*
	379	* Free the host once all references to it have been dropped.
	380	*/
	381	void mmc_free_host(struct mmc_host *host)
	382	{
ff3112f5 PO	383	spin_lock(&mmc_host_lock);
	384	idr_remove(&mmc_host_idr, host->index);
	385	spin_unlock(&mmc_host_lock);
	386
b93931a6 PO	387	put_device(&host->class_dev);
	388	}
	389
	390	EXPORT_SYMBOL(mmc_free_host);