mmc.c

基于三星2410b,linux下的SD卡驱动

	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, u32 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");