Revision dda50e716dc9451f40eebfb2902c260e4f62cf34 authored by Andi Kleen on 17 May 2005, 04:53:25 UTC, committed by Linus Torvalds on 17 May 2005, 14:59:14 UTC
The new TSC sync algorithm recently submitted did not work too well.

The result was that some MP machines where the TSC came up of the BIOS very
unsynchronized and that did not have HPET support were nearly unusable because
the time would jump forwards and backwards between CPUs.

After a lot of research ;-) and some more prototypes I ended up with just
using the one from IA64 which looks best.  It has some internal self tuning
that should adapt to changing interconnect latencies.  It holds up in my tests
so far.

I believe it was originally written by David Mosberger, I just ported it over
to x86-64.  See the inline comment for a description.

This cleans up the code because it uses smp_call_function for syncing instead
of having custom hooks in SMP bootup.

Please note that the cycle numbers it outputs are too optimistic because they
do not take into account the latency of WRMSR and RDTSC, which can be hundreds
of cycles.  It seems to be able to sync a dual Opteron to 200-300 cycles,
which is probably good enough.

There is a timing window during AP bootup where interrupts can see
inconsistent time before the TSC is synced.  It is hard to avoid unfortunately
because we can only do the TSC sync after some setup, and we need to enable
interrupts before that.  I just ignored it for now.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 93ef70a
Raw File
mmc.c
/*
 *  linux/drivers/mmc/mmc.c
 *
 *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
 *
 * 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.
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/pagemap.h>
#include <linux/err.h>

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

#include "mmc.h"

#ifdef CONFIG_MMC_DEBUG
#define DBG(x...)	printk(KERN_DEBUG x)
#else
#define DBG(x...)	do { } while (0)
#endif

#define CMD_RETRIES	3

/*
 * OCR Bit positions to 10s of Vdd mV.
 */
static const unsigned short mmc_ocr_bit_to_vdd[] = {
	150,	155,	160,	165,	170,	180,	190,	200,
	210,	220,	230,	240,	250,	260,	270,	280,
	290,	300,	310,	320,	330,	340,	350,	360
};

static const unsigned int tran_exp[] = {
	10000,		100000,		1000000,	10000000,
	0,		0,		0,		0
};

static const unsigned char tran_mant[] = {
	0,	10,	12,	13,	15,	20,	25,	30,
	35,	40,	45,	50,	55,	60,	70,	80,
};

static const unsigned int tacc_exp[] = {
	1,	10,	100,	1000,	10000,	100000,	1000000, 10000000,
};

static const unsigned int tacc_mant[] = {
	0,	10,	12,	13,	15,	20,	25,	30,
	35,	40,	45,	50,	55,	60,	70,	80,
};


/**
 *	mmc_request_done - finish processing an MMC command
 *	@host: MMC host which completed command
 *	@mrq: MMC request which completed
 *
 *	MMC drivers should call this function when they have completed
 *	their processing of a command.  This should be called before the
 *	data part of the command has completed.
 */
void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
{
	struct mmc_command *cmd = mrq->cmd;
	int err = mrq->cmd->error;
	DBG("MMC: req done (%02x): %d: %08x %08x %08x %08x\n", cmd->opcode,
	    err, cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3]);

	if (err && cmd->retries) {
		cmd->retries--;
		cmd->error = 0;
		host->ops->request(host, mrq);
	} else if (mrq->done) {
		mrq->done(mrq);
	}
}

EXPORT_SYMBOL(mmc_request_done);

/**
 *	mmc_start_request - start a command on a host
 *	@host: MMC host to start command on
 *	@mrq: MMC request to start
 *
 *	Queue a command on the specified host.  We expect the
 *	caller to be holding the host lock with interrupts disabled.
 */
void
mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
{
	DBG("MMC: starting cmd %02x arg %08x flags %08x\n",
	    mrq->cmd->opcode, mrq->cmd->arg, mrq->cmd->flags);

	WARN_ON(host->card_busy == NULL);

	mrq->cmd->error = 0;
	mrq->cmd->mrq = mrq;
	if (mrq->data) {
		mrq->cmd->data = mrq->data;
		mrq->data->error = 0;
		mrq->data->mrq = mrq;
		if (mrq->stop) {
			mrq->data->stop = mrq->stop;
			mrq->stop->error = 0;
			mrq->stop->mrq = mrq;
		}
	}
	host->ops->request(host, mrq);
}

EXPORT_SYMBOL(mmc_start_request);

static void mmc_wait_done(struct mmc_request *mrq)
{
	complete(mrq->done_data);
}

int mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq)
{
	DECLARE_COMPLETION(complete);

	mrq->done_data = &complete;
	mrq->done = mmc_wait_done;

	mmc_start_request(host, mrq);

	wait_for_completion(&complete);

	return 0;
}

EXPORT_SYMBOL(mmc_wait_for_req);

/**
 *	mmc_wait_for_cmd - start a command and wait for completion
 *	@host: MMC host to start command
 *	@cmd: MMC command to start
 *	@retries: maximum number of retries
 *
 *	Start a new MMC command for a host, and wait for the command
 *	to complete.  Return any error that occurred while the command
 *	was executing.  Do not attempt to parse the response.
 */
int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd, int retries)
{
	struct mmc_request mrq;

	BUG_ON(host->card_busy == NULL);

	memset(&mrq, 0, sizeof(struct mmc_request));

	memset(cmd->resp, 0, sizeof(cmd->resp));
	cmd->retries = retries;

	mrq.cmd = cmd;
	cmd->data = NULL;

	mmc_wait_for_req(host, &mrq);

	return cmd->error;
}

EXPORT_SYMBOL(mmc_wait_for_cmd);



/**
 *	__mmc_claim_host - exclusively claim a host
 *	@host: mmc host to claim
 *	@card: mmc card to claim host for
 *
 *	Claim a host for a set of operations.  If a valid card
 *	is passed and this wasn't the last card selected, select
 *	the card before returning.
 *
 *	Note: you should use mmc_card_claim_host or mmc_claim_host.
 */
int __mmc_claim_host(struct mmc_host *host, struct mmc_card *card)
{
	DECLARE_WAITQUEUE(wait, current);
	unsigned long flags;
	int err = 0;

	add_wait_queue(&host->wq, &wait);
	spin_lock_irqsave(&host->lock, flags);
	while (1) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (host->card_busy == NULL)
			break;
		spin_unlock_irqrestore(&host->lock, flags);
		schedule();
		spin_lock_irqsave(&host->lock, flags);
	}
	set_current_state(TASK_RUNNING);
	host->card_busy = card;
	spin_unlock_irqrestore(&host->lock, flags);
	remove_wait_queue(&host->wq, &wait);

	if (card != (void *)-1 && host->card_selected != card) {
		struct mmc_command cmd;

		host->card_selected = card;

		cmd.opcode = MMC_SELECT_CARD;
		cmd.arg = card->rca << 16;
		cmd.flags = MMC_RSP_R1;

		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
	}

	return err;
}

EXPORT_SYMBOL(__mmc_claim_host);

/**
 *	mmc_release_host - release a host
 *	@host: mmc host to release
 *
 *	Release a MMC host, allowing others to claim the host
 *	for their operations.
 */
void mmc_release_host(struct mmc_host *host)
{
	unsigned long flags;

	BUG_ON(host->card_busy == NULL);

	spin_lock_irqsave(&host->lock, flags);
	host->card_busy = NULL;
	spin_unlock_irqrestore(&host->lock, flags);

	wake_up(&host->wq);
}

EXPORT_SYMBOL(mmc_release_host);

/*
 * Ensure that no card is selected.
 */
static void mmc_deselect_cards(struct mmc_host *host)
{
	struct mmc_command cmd;

	if (host->card_selected) {
		host->card_selected = NULL;

		cmd.opcode = MMC_SELECT_CARD;
		cmd.arg = 0;
		cmd.flags = MMC_RSP_NONE;

		mmc_wait_for_cmd(host, &cmd, 0);
	}
}


static inline void mmc_delay(unsigned int ms)
{
	if (ms < HZ / 1000) {
		yield();
		mdelay(ms);
	} else {
		msleep_interruptible (ms);
	}
}

/*
 * Mask off any voltages we don't support and select
 * the lowest voltage
 */
static u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
{
	int bit;

	ocr &= host->ocr_avail;

	bit = ffs(ocr);
	if (bit) {
		bit -= 1;

		ocr = 3 << bit;

		host->ios.vdd = bit;
		host->ops->set_ios(host, &host->ios);
	} else {
		ocr = 0;
	}

	return ocr;
}

#define UNSTUFF_BITS(resp,start,size)					\
	({								\
		const int __size = size;				\
		const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1;	\
		const int __off = 3 - ((start) / 32);			\
		const int __shft = (start) & 31;			\
		u32 __res;						\
									\
		__res = resp[__off] >> __shft;				\
		if (__size + __shft > 32)				\
			__res |= resp[__off-1] << ((32 - __shft) % 32);	\
		__res & __mask;						\
	})

/*
 * Given the decoded CSD structure, decode the raw CID to our CID structure.
 */
static void mmc_decode_cid(struct mmc_card *card)
{
	u32 *resp = card->raw_cid;

	memset(&card->cid, 0, sizeof(struct mmc_cid));

	/*
	 * The selection of the format here is guesswork based upon
	 * information people have sent to date.
	 */
	switch (card->csd.mmca_vsn) {
	case 0: /* MMC v1.? */
	case 1: /* MMC v1.4 */
		card->cid.manfid	= UNSTUFF_BITS(resp, 104, 24);
		card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
		card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
		card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
		card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
		card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
		card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
		card->cid.prod_name[6]	= UNSTUFF_BITS(resp, 48, 8);
		card->cid.hwrev		= UNSTUFF_BITS(resp, 44, 4);
		card->cid.fwrev		= UNSTUFF_BITS(resp, 40, 4);
		card->cid.serial	= UNSTUFF_BITS(resp, 16, 24);
		card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
		card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
		break;

	case 2: /* MMC v2.x ? */
	case 3: /* MMC v3.x ? */
		card->cid.manfid	= UNSTUFF_BITS(resp, 120, 8);
		card->cid.oemid		= UNSTUFF_BITS(resp, 104, 16);
		card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
		card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
		card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
		card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
		card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
		card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
		card->cid.serial	= UNSTUFF_BITS(resp, 16, 32);
		card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
		card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
		break;

	default:
		printk("%s: card has unknown MMCA version %d\n",
			card->host->host_name, card->csd.mmca_vsn);
		mmc_card_set_bad(card);
		break;
	}
}

/*
 * Given a 128-bit response, decode to our card CSD structure.
 */
static void mmc_decode_csd(struct mmc_card *card)
{
	struct mmc_csd *csd = &card->csd;
	unsigned int e, m, csd_struct;
	u32 *resp = card->raw_csd;

	/*
	 * We only understand CSD structure v1.1 and v2.
	 * v2 has extra information in bits 15, 11 and 10.
	 */
	csd_struct = UNSTUFF_BITS(resp, 126, 2);
	if (csd_struct != 1 && csd_struct != 2) {
		printk("%s: unrecognised CSD structure version %d\n",
			card->host->host_name, csd_struct);
		mmc_card_set_bad(card);
		return;
	}

	csd->mmca_vsn	 = UNSTUFF_BITS(resp, 122, 4);
	m = UNSTUFF_BITS(resp, 115, 4);
	e = UNSTUFF_BITS(resp, 112, 3);
	csd->tacc_ns	 = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
	csd->tacc_clks	 = UNSTUFF_BITS(resp, 104, 8) * 100;

	m = UNSTUFF_BITS(resp, 99, 4);
	e = UNSTUFF_BITS(resp, 96, 3);
	csd->max_dtr	  = tran_exp[e] * tran_mant[m];
	csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);

	e = UNSTUFF_BITS(resp, 47, 3);
	m = UNSTUFF_BITS(resp, 62, 12);
	csd->capacity	  = (1 + m) << (e + 2);

	csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
}

/*
 * Locate a MMC card on this MMC host given a raw CID.
 */
static struct mmc_card *mmc_find_card(struct mmc_host *host, u32 *raw_cid)
{
	struct mmc_card *card;

	list_for_each_entry(card, &host->cards, node) {
		if (memcmp(card->raw_cid, raw_cid, sizeof(card->raw_cid)) == 0)
			return card;
	}
	return NULL;
}

/*
 * Allocate a new MMC card, and assign a unique RCA.
 */
static struct mmc_card *
mmc_alloc_card(struct mmc_host *host, u32 *raw_cid, unsigned int *frca)
{
	struct mmc_card *card, *c;
	unsigned int rca = *frca;

	card = kmalloc(sizeof(struct mmc_card), GFP_KERNEL);
	if (!card)
		return ERR_PTR(-ENOMEM);

	mmc_init_card(card, host);
	memcpy(card->raw_cid, raw_cid, sizeof(card->raw_cid));

 again:
	list_for_each_entry(c, &host->cards, node)
		if (c->rca == rca) {
			rca++;
			goto again;
		}

	card->rca = rca;

	*frca = rca;

	return card;
}

/*
 * Tell attached cards to go to IDLE state
 */
static void mmc_idle_cards(struct mmc_host *host)
{
	struct mmc_command cmd;

	cmd.opcode = MMC_GO_IDLE_STATE;
	cmd.arg = 0;
	cmd.flags = MMC_RSP_NONE;

	mmc_wait_for_cmd(host, &cmd, 0);

	mmc_delay(1);
}

/*
 * Apply power to the MMC stack.
 */
static void mmc_power_up(struct mmc_host *host)
{
	int bit = fls(host->ocr_avail) - 1;

	host->ios.vdd = bit;
	host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
	host->ios.power_mode = MMC_POWER_UP;
	host->ops->set_ios(host, &host->ios);

	mmc_delay(1);

	host->ios.clock = host->f_min;
	host->ios.power_mode = MMC_POWER_ON;
	host->ops->set_ios(host, &host->ios);

	mmc_delay(2);
}

static void mmc_power_off(struct mmc_host *host)
{
	host->ios.clock = 0;
	host->ios.vdd = 0;
	host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
	host->ios.power_mode = MMC_POWER_OFF;
	host->ops->set_ios(host, &host->ios);
}

static int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
{
	struct mmc_command cmd;
	int i, err = 0;

	cmd.opcode = MMC_SEND_OP_COND;
	cmd.arg = ocr;
	cmd.flags = MMC_RSP_R3;

	for (i = 100; i; i--) {
		err = mmc_wait_for_cmd(host, &cmd, 0);
		if (err != MMC_ERR_NONE)
			break;

		if (cmd.resp[0] & MMC_CARD_BUSY || ocr == 0)
			break;

		err = MMC_ERR_TIMEOUT;

		mmc_delay(10);
	}

	if (rocr)
		*rocr = cmd.resp[0];

	return err;
}

/*
 * Discover cards by requesting their CID.  If this command
 * times out, it is not an error; there are no further cards
 * to be discovered.  Add new cards to the list.
 *
 * Create a mmc_card entry for each discovered card, assigning
 * it an RCA, and save the raw CID for decoding later.
 */
static void mmc_discover_cards(struct mmc_host *host)
{
	struct mmc_card *card;
	unsigned int first_rca = 1, err;

	while (1) {
		struct mmc_command cmd;

		cmd.opcode = MMC_ALL_SEND_CID;
		cmd.arg = 0;
		cmd.flags = MMC_RSP_R2;

		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
		if (err == MMC_ERR_TIMEOUT) {
			err = MMC_ERR_NONE;
			break;
		}
		if (err != MMC_ERR_NONE) {
			printk(KERN_ERR "%s: error requesting CID: %d\n",
				host->host_name, err);
			break;
		}

		card = mmc_find_card(host, cmd.resp);
		if (!card) {
			card = mmc_alloc_card(host, cmd.resp, &first_rca);
			if (IS_ERR(card)) {
				err = PTR_ERR(card);
				break;
			}
			list_add(&card->node, &host->cards);
		}

		card->state &= ~MMC_STATE_DEAD;

		cmd.opcode = MMC_SET_RELATIVE_ADDR;
		cmd.arg = card->rca << 16;
		cmd.flags = MMC_RSP_R1;

		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
		if (err != MMC_ERR_NONE)
			mmc_card_set_dead(card);
	}
}

static void mmc_read_csds(struct mmc_host *host)
{
	struct mmc_card *card;

	list_for_each_entry(card, &host->cards, node) {
		struct mmc_command cmd;
		int err;

		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
			continue;

		cmd.opcode = MMC_SEND_CSD;
		cmd.arg = card->rca << 16;
		cmd.flags = MMC_RSP_R2;

		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
		if (err != MMC_ERR_NONE) {
			mmc_card_set_dead(card);
			continue;
		}

		memcpy(card->raw_csd, cmd.resp, sizeof(card->raw_csd));

		mmc_decode_csd(card);
		mmc_decode_cid(card);
	}
}

static unsigned int mmc_calculate_clock(struct mmc_host *host)
{
	struct mmc_card *card;
	unsigned int max_dtr = host->f_max;

	list_for_each_entry(card, &host->cards, node)
		if (!mmc_card_dead(card) && max_dtr > card->csd.max_dtr)
			max_dtr = card->csd.max_dtr;

	DBG("MMC: selected %d.%03dMHz transfer rate\n",
	    max_dtr / 1000000, (max_dtr / 1000) % 1000);

	return max_dtr;
}

/*
 * Check whether cards we already know about are still present.
 * We do this by requesting status, and checking whether a card
 * responds.
 *
 * A request for status does not cause a state change in data
 * transfer mode.
 */
static void mmc_check_cards(struct mmc_host *host)
{
	struct list_head *l, *n;

	mmc_deselect_cards(host);

	list_for_each_safe(l, n, &host->cards) {
		struct mmc_card *card = mmc_list_to_card(l);
		struct mmc_command cmd;
		int err;

		cmd.opcode = MMC_SEND_STATUS;
		cmd.arg = card->rca << 16;
		cmd.flags = MMC_RSP_R1;

		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
		if (err == MMC_ERR_NONE)
			continue;

		mmc_card_set_dead(card);
	}
}

static void mmc_setup(struct mmc_host *host)
{
	if (host->ios.power_mode != MMC_POWER_ON) {
		int err;
		u32 ocr;

		mmc_power_up(host);
		mmc_idle_cards(host);

		err = mmc_send_op_cond(host, 0, &ocr);
		if (err != MMC_ERR_NONE)
			return;

		host->ocr = mmc_select_voltage(host, ocr);

		/*
		 * Since we're changing the OCR value, we seem to
		 * need to tell some cards to go back to the idle
		 * state.  We wait 1ms to give cards time to
		 * respond.
		 */
		if (host->ocr)
			mmc_idle_cards(host);
	} else {
		host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
		host->ios.clock = host->f_min;
		host->ops->set_ios(host, &host->ios);

		/*
		 * We should remember the OCR mask from the existing
		 * cards, and detect the new cards OCR mask, combine
		 * the two and re-select the VDD.  However, if we do
		 * change VDD, we should do an idle, and then do a
		 * full re-initialisation.  We would need to notify
		 * drivers so that they can re-setup the cards as
		 * well, while keeping their queues at bay.
		 *
		 * For the moment, we take the easy way out - if the
		 * new cards don't like our currently selected VDD,
		 * they drop off the bus.
		 */
	}

	if (host->ocr == 0)
		return;

	/*
	 * Send the selected OCR multiple times... until the cards
	 * all get the idea that they should be ready for CMD2.
	 * (My SanDisk card seems to need this.)
	 */
	mmc_send_op_cond(host, host->ocr, NULL);

	mmc_discover_cards(host);

	/*
	 * Ok, now switch to push-pull mode.
	 */
	host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
	host->ops->set_ios(host, &host->ios);

	mmc_read_csds(host);
}


/**
 *	mmc_detect_change - process change of state on a MMC socket
 *	@host: host which changed state.
 *
 *	All we know is that card(s) have been inserted or removed
 *	from the socket(s).  We don't know which socket or cards.
 */
void mmc_detect_change(struct mmc_host *host)
{
	schedule_work(&host->detect);
}

EXPORT_SYMBOL(mmc_detect_change);


static void mmc_rescan(void *data)
{
	struct mmc_host *host = data;
	struct list_head *l, *n;

	mmc_claim_host(host);

	if (host->ios.power_mode == MMC_POWER_ON)
		mmc_check_cards(host);

	mmc_setup(host);

	if (!list_empty(&host->cards)) {
		/*
		 * (Re-)calculate the fastest clock rate which the
		 * attached cards and the host support.
		 */
		host->ios.clock = mmc_calculate_clock(host);
		host->ops->set_ios(host, &host->ios);
	}

	mmc_release_host(host);

	list_for_each_safe(l, n, &host->cards) {
		struct mmc_card *card = mmc_list_to_card(l);

		/*
		 * If this is a new and good card, register it.
		 */
		if (!mmc_card_present(card) && !mmc_card_dead(card)) {
			if (mmc_register_card(card))
				mmc_card_set_dead(card);
			else
				mmc_card_set_present(card);
		}

		/*
		 * If this card is dead, destroy it.
		 */
		if (mmc_card_dead(card)) {
			list_del(&card->node);
			mmc_remove_card(card);
		}
	}

	/*
	 * If we discover that there are no cards on the
	 * bus, turn off the clock and power down.
	 */
	if (list_empty(&host->cards))
		mmc_power_off(host);
}


/**
 *	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)
{
	struct mmc_host *host;

	host = kmalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
	if (host) {
		memset(host, 0, sizeof(struct mmc_host) + extra);

		spin_lock_init(&host->lock);
		init_waitqueue_head(&host->wq);
		INIT_LIST_HEAD(&host->cards);
		INIT_WORK(&host->detect, mmc_rescan, host);

		host->dev = dev;

		/*
		 * By default, hosts do not support SGIO or large requests.
		 * They have to set these according to their abilities.
		 */
		host->max_hw_segs = 1;
		host->max_phys_segs = 1;
		host->max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
		host->max_seg_size = PAGE_CACHE_SIZE;
	}

	return host;
}

EXPORT_SYMBOL(mmc_alloc_host);

/**
 *	mmc_add_host - initialise host hardware
 *	@host: mmc host
 */
int mmc_add_host(struct mmc_host *host)
{
	static unsigned int host_num;

	snprintf(host->host_name, sizeof(host->host_name),
		 "mmc%d", host_num++);

	mmc_power_off(host);
	mmc_detect_change(host);

	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.
 */
void mmc_remove_host(struct mmc_host *host)
{
	struct list_head *l, *n;

	list_for_each_safe(l, n, &host->cards) {
		struct mmc_card *card = mmc_list_to_card(l);

		mmc_remove_card(card);
	}

	mmc_power_off(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)
{
	flush_scheduled_work();
	kfree(host);
}

EXPORT_SYMBOL(mmc_free_host);

#ifdef CONFIG_PM

/**
 *	mmc_suspend_host - suspend a host
 *	@host: mmc host
 *	@state: suspend mode (PM_SUSPEND_xxx)
 */
int mmc_suspend_host(struct mmc_host *host, pm_message_t state)
{
	mmc_claim_host(host);
	mmc_deselect_cards(host);
	mmc_power_off(host);
	mmc_release_host(host);

	return 0;
}

EXPORT_SYMBOL(mmc_suspend_host);

/**
 *	mmc_resume_host - resume a previously suspended host
 *	@host: mmc host
 */
int mmc_resume_host(struct mmc_host *host)
{
	mmc_detect_change(host);

	return 0;
}

EXPORT_SYMBOL(mmc_resume_host);

#endif

MODULE_LICENSE("GPL");
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