Re: [RFC PATCH v3.1 20/27] mmc: sdhci-uhs2: add request() and others

[Adrian Hunter <adrian.hunter@intel.com>]

On 1/12/20 4:40 am, AKASHI Takahiro wrote:
> On Thu, Nov 26, 2020 at 10:18:44AM +0200, Adrian Hunter wrote:
>> On 6/11/20 4:27 am, AKASHI Takahiro wrote:
>>> This is a sdhci version of mmc's request operation.
>>> It covers both UHS-I and UHS-II.
>>>
>>> Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>>> ---
>>>  drivers/mmc/host/sdhci-uhs2.c | 529 ++++++++++++++++++++++++++++++++++
>>>  drivers/mmc/host/sdhci.c      |  93 +++---
>>>  drivers/mmc/host/sdhci.h      |  21 ++
>>>  3 files changed, 610 insertions(+), 33 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
>>> index d8afb99a9918..36e52553977a 100644
>>> --- a/drivers/mmc/host/sdhci-uhs2.c
>>> +++ b/drivers/mmc/host/sdhci-uhs2.c
>>> @@ -13,6 +13,7 @@
>>>  #include <linux/delay.h>
>>>  #include <linux/ktime.h>
>>>  #include <linux/module.h>
>>> +#include <linux/mmc/mmc.h>
>>>  
>>>  #include "sdhci.h"
>>>  #include "sdhci-uhs2.h"
>>> @@ -394,6 +395,27 @@ static int sdhci_uhs2_check_dormant(struct sdhci_host *host)
>>>  	return 0;
>>>  }
>>>  
>>> +/* TODO: move them to a header */
>>> +#if IS_REACHABLE(CONFIG_LEDS_CLASS)
>>> +static inline void sdhci_led_activate(struct sdhci_host *host)
>>> +{
>>> +}
>>> +
>>> +static inline void sdhci_led_deactivate(struct sdhci_host *host)
>>> +{
>>> +}
>>> +#else
>>> +static inline void sdhci_led_activate(struct sdhci_host *host)
>>> +{
>>> +	__sdhci_led_activate(host);
>>> +}
>>> +
>>> +static inline void sdhci_led_deactivate(struct sdhci_host *host)
>>> +{
>>> +	__sdhci_led_deactivate(host);
>>> +}
>>> +#endif
>>
>> Unless you need LED support, let's drop  it
> 
> Okay
> 
>>> +
>>>  /*****************************************************************************\
>>>   *                                                                           *
>>>   * MMC callbacks                                                             *
>>> @@ -523,6 +545,512 @@ static int sdhci_uhs2_set_reg(struct mmc_host *mmc, enum uhs2_act act)
>>>  	return err;
>>>  }
>>>  
>>> +static bool sdhci_uhs2_send_command(struct sdhci_host *host,
>>> +				    struct mmc_command *cmd);
>>> +static bool sdhci_uhs2_send_command_retry(struct sdhci_host *host,
>>> +				     struct mmc_command *cmd,
>>> +				     unsigned long flags);
>>
>> Always order functions so that early function declarations are not needed
> 
> Will try.
> 
>>> +
>>> +void sdhci_uhs2_request(struct mmc_host *mmc, struct mmc_request *mrq)
>>> +{
>>> +	struct sdhci_host *host = mmc_priv(mmc);
>>> +	struct mmc_command *cmd;
>>> +	unsigned long flags;
>>> +	bool present;
>>> +
>>> +	/* FIXME: check more flags? */
>>> +	if (!host->mmc->flags & MMC_UHS2_SUPPORT) {
>>
>>
>> 	if (sdhci_uhs2_mode(host))
>>
>>> +		sdhci_request(mmc, mrq);
>>> +		return;
>>> +	}
>>> +
>>> +	/* Firstly check card presence */
>>> +	present = mmc->ops->get_cd(mmc);
>>
>> Checking CD here is another legacy hangover.  Should be able to check the
>> bus power instead. i.e. if the card has been removed, the bus power (bit-0
>> Power Control reg) should get set to 0.  That can be checked under spin lock.
> 
> Replace it with check against SDHCI_POWER_ON.
> 
>>> +
>>> +	spin_lock_irqsave(&host->lock, flags);
>>> +
>>> +	sdhci_led_activate(host);
>>
>> Drop support for sdhci LEDs unless yoy are using them
> 
> Sure
> 
>>> +
>>> +	if (sdhci_present_error(host, mrq->cmd, present))
>>> +		goto out_finish;
>>> +
>>> +	cmd = sdhci_manual_cmd23(host, mrq) ? mrq->sbc : mrq->cmd;
>>
>> UHS2 doesn't use CMD23 does it?
> 
> I don't know. Will replace it with
>     cmd = mrq->sbc ? mrq->sbc : mrq->cmd;

UHS-II spec says to set LM=1 and set TLEN instead of using CMD23.

Just ignore mrq->sbc (set block count) i.e. cmd = mrq->cmd

> 
>>> +
>>> +	if (!sdhci_uhs2_send_command_retry(host, cmd, flags))
>>
>> Don't use sdhci_uhs2_send_command_retry.  sdhci_send_command_retry is again
>> dealing with legacy hangover.  The inhibit bits should not be set.  If they
>> are it can be an error immediately.  So just use sdhci_uhs2_send_commend()
> 
> Will follow your suggestion.
> 
>>> +		goto out_finish;
>>> +
>>> +	spin_unlock_irqrestore(&host->lock, flags);
>>> +
>>> +	return;
>>> +
>>> +out_finish:
>>> +	sdhci_finish_mrq(host, mrq);
>>> +	spin_unlock_irqrestore(&host->lock, flags);
>>> +}
>>> +EXPORT_SYMBOL_GPL(sdhci_uhs2_request);
>>> +
>>> +int sdhci_uhs2_request_atomic(struct mmc_host *mmc, struct mmc_request *mrq)
>>
>> Should end up being able simply to call sdhci_uhs2_request (or vice versa)
> 
> Well, there is one difference,i.e. whether we should check "card presence"
> (or POWER_ON), isn't it?
> I think we should preserve this difference.
> 
> Or we may simply remove _atomic version since there is no user for now.
> Which do you prefer?

Checking card-detect (GPIO) is not guaranteed to be atomic, but reading the
bus power register to check presence is.  So if you do that, then the
request function can be atomic.  I guess the _request_atomic() one is the
one to implement, and then the _request() fn can call _request_atomic()

> 
>>> +{
>>> +	struct sdhci_host *host = mmc_priv(mmc);
>>> +	struct mmc_command *cmd;
>>> +	unsigned long flags;
>>> +	int ret = 0;
>>> +
>>> +	if (!host->mmc->flags & MMC_UHS2_SUPPORT)
>>> +		return sdhci_request_atomic(mmc, mrq);
>>> +
>>> +	spin_lock_irqsave(&host->lock, flags);
>>> +
>>> +	if (sdhci_present_error(host, mrq->cmd, true)) {
>>> +		sdhci_finish_mrq(host, mrq);
>>> +		goto out_finish;
>>> +	}
>>> +
>>> +	cmd = sdhci_manual_cmd23(host, mrq) ? mrq->sbc : mrq->cmd;
>>> +
>>> +	/*
>>> +	 * The HSQ may send a command in interrupt context without polling
>>> +	 * the busy signaling, which means we should return BUSY if controller
>>> +	 * has not released inhibit bits to allow HSQ trying to send request
>>> +	 * again in non-atomic context. So we should not finish this request
>>> +	 * here.
>>> +	 */
>>> +	if (!sdhci_uhs2_send_command(host, cmd))
>>> +		ret = -EBUSY;
>>> +	else
>>> +		sdhci_led_activate(host);
>>> +
>>> +out_finish:
>>> +	spin_unlock_irqrestore(&host->lock, flags);
>>> +	return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(sdhci_uhs2_request_atomic);
>>> +
>>> +/*****************************************************************************\
>>> + *                                                                           *
>>> + * Core functions                                                            *
>>> + *                                                                           *
>>> +\*****************************************************************************/
>>> +
>>> +static void sdhci_uhs2_prepare_data(struct sdhci_host *host,
>>> +				    struct mmc_command *cmd)
>>> +{
>>> +	struct mmc_data *data = cmd->data;
>>> +
>>> +	sdhci_initialize_data(host, data);
>>> +
>>> +	sdhci_prepare_dma(host, data);
>>> +
>>> +	sdhci_writew(host, data->blksz, SDHCI_UHS2_BLOCK_SIZE);
>>> +	sdhci_writew(host, data->blocks, SDHCI_UHS2_BLOCK_COUNT);
>>> +}
>>> +
>>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
>>> +static void sdhci_uhs2_external_dma_prepare_data(struct sdhci_host *host,
>>> +						 struct mmc_command *cmd)
>>> +{
>>> +	if (!sdhci_external_dma_setup(host, cmd)) {
>>> +		__sdhci_external_dma_prepare_data(host, cmd);
>>> +	} else {
>>> +		sdhci_external_dma_release(host);
>>> +		pr_err("%s: Cannot use external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",
>>> +		       mmc_hostname(host->mmc));
>>> +		sdhci_uhs2_prepare_data(host, cmd);
>>> +	}
>>> +}
>>> +#else
>>> +static inline void sdhci_uhs2_external_dma_prepare_data(struct sdhci_host *host,
>>> +							struct mmc_command *cmd)
>>> +{
>>> +	/* This should never happen */
>>> +	WARN_ON_ONCE(1);
>>> +}
>>> +
>>> +static inline void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
>>> +						   struct mmc_command *cmd)
>>> +{
>>> +}
>>> +#endif /* CONFIG_MMC_SDHCI_EXTERNAL_DMA */
>>
>> Let's start without support for external DMA - unless you need it
> 
> Okay
> 
>>> +
>>> +static void sdhci_uhs2_finish_data(struct sdhci_host *host)
>>> +{
>>> +	struct mmc_data *data = host->data;
>>> +
>>> +	__sdhci_finish_data_common(host);
>>> +
>>> +	/*
>>> +	 *  FIXME: Is this condition needed?
>>> +	    if (host->mmc->flags & MMC_UHS2_INITIALIZED)
>>> +	 */
>>> +	__sdhci_finish_mrq(host, data->mrq);
>>> +}
>>> +
>>> +static void sdhci_uhs2_set_transfer_mode(struct sdhci_host *host,
>>> +					 struct mmc_command *cmd)
>>> +{
>>> +	u16 mode;
>>> +	struct mmc_data *data = cmd->data;
>>> +	u16 arg;
>>> +
>>> +	if (!data) {
>>> +		/* clear Auto CMD settings for no data CMDs */
>>> +		arg = cmd->uhs2_cmd->arg;
>>> +		if ((((arg & 0xF) << 8) | ((arg >> 8) & 0xFF)) ==
>>> +		       UHS2_DEV_CMD_TRANS_ABORT) {
>>> +			mode =  0;
>>> +		} else {
>>> +			mode = sdhci_readw(host, SDHCI_UHS2_TRANS_MODE);
>>> +			if (cmd->opcode == MMC_STOP_TRANSMISSION ||
>>> +			    cmd->opcode == MMC_ERASE)
>>> +				mode |= SDHCI_UHS2_TRNS_WAIT_EBSY;
>>> +			else
>>> +				/* send status mode */
>>> +				if (cmd->opcode == MMC_SEND_STATUS)
>>> +					mode = 0;
>>> +		}
>>> +
>>> +		if (IS_ENABLED(CONFIG_MMC_DEBUG))
>>> +			DBG("UHS2 no data trans mode is 0x%x.\n", mode);
>>> +
>>> +		sdhci_writew(host, mode, SDHCI_UHS2_TRANS_MODE);
>>> +		return;
>>> +	}
>>> +
>>> +	WARN_ON(!host->data);
>>> +
>>> +	mode = SDHCI_UHS2_TRNS_BLK_CNT_EN | SDHCI_UHS2_TRNS_WAIT_EBSY;
>>> +	if (data->flags & MMC_DATA_WRITE)
>>> +		mode |= SDHCI_UHS2_TRNS_DATA_TRNS_WRT;
>>> +
>>> +	if (data->blocks == 1 &&
>>> +	    data->blksz != 512 &&
>>> +	    cmd->opcode != MMC_READ_SINGLE_BLOCK &&
>>> +	    cmd->opcode != MMC_WRITE_BLOCK) {
>>> +		mode &= ~SDHCI_UHS2_TRNS_BLK_CNT_EN;
>>> +		mode |= SDHCI_UHS2_TRNS_BLK_BYTE_MODE;
>>> +	}
>>> +
>>> +	if (host->flags & SDHCI_REQ_USE_DMA)
>>> +		mode |= SDHCI_UHS2_TRNS_DMA;
>>> +
>>> +	if ((host->mmc->flags & MMC_UHS2_2L_HD) && !cmd->uhs2_tmode0_flag)
>>> +		mode |= SDHCI_UHS2_TRNS_2L_HD;
>>> +
>>> +	sdhci_writew(host, mode, SDHCI_UHS2_TRANS_MODE);
>>> +
>>> +	if (IS_ENABLED(CONFIG_MMC_DEBUG))
>>> +		DBG("UHS2 trans mode is 0x%x.\n", mode);
>>> +}
>>> +
>>> +static void __sdhci_uhs2_send_command(struct sdhci_host *host,
>>> +				      struct mmc_command *cmd)
>>> +{
>>> +	int i, j;
>>> +	int cmd_reg;
>>> +
>>> +	if (host->mmc->flags & MMC_UHS2_INITIALIZED) {
>>> +		if (!cmd->uhs2_cmd) {
>>> +			pr_err("%s: fatal error, no uhs2_cmd!\n",
>>> +			       mmc_hostname(host->mmc));
>>> +			return;
>>> +		}
>>> +	}
>>> +
>>> +	i = 0;
>>> +	sdhci_writel(host,
>>> +		     ((u32)cmd->uhs2_cmd->arg << 16) |
>>> +				(u32)cmd->uhs2_cmd->header,
>>> +		     SDHCI_UHS2_CMD_PACKET + i);
>>> +	i += 4;
>>> +
>>> +	/*
>>> +	 * Per spec, playload (config) should be MSB before sending out.
>>> +	 * But we don't need convert here because had set payload as
>>> +	 * MSB when preparing config read/write commands.
>>> +	 */
>>> +	for (j = 0; j < cmd->uhs2_cmd->payload_len / sizeof(u32); j++) {
>>> +		sdhci_writel(host, *(cmd->uhs2_cmd->payload + j),
>>> +			     SDHCI_UHS2_CMD_PACKET + i);
>>> +		i += 4;
>>> +	}
>>> +
>>> +	for ( ; i < SDHCI_UHS2_CMD_PACK_MAX_LEN; i += 4)
>>> +		sdhci_writel(host, 0, SDHCI_UHS2_CMD_PACKET + i);
>>> +
>>> +	if (IS_ENABLED(CONFIG_MMC_DEBUG)) {
>>> +		DBG("UHS2 CMD packet_len = %d.\n", cmd->uhs2_cmd->packet_len);
>>> +		for (i = 0; i < cmd->uhs2_cmd->packet_len; i++)
>>> +			DBG("UHS2 CMD_PACKET[%d] = 0x%x.\n", i,
>>> +			    sdhci_readb(host, SDHCI_UHS2_CMD_PACKET + i));
>>> +	}
>>> +
>>> +	cmd_reg = cmd->uhs2_cmd->packet_len <<
>>> +		SDHCI_UHS2_COMMAND_PACK_LEN_SHIFT;
>>> +	if ((cmd->flags & MMC_CMD_MASK) == MMC_CMD_ADTC)
>>> +		cmd_reg |= SDHCI_UHS2_COMMAND_DATA;
>>> +	if (cmd->opcode == MMC_STOP_TRANSMISSION)
>>> +		cmd_reg |= SDHCI_UHS2_COMMAND_CMD12;
>>> +
>>> +	/* UHS2 Native ABORT */
>>> +	if ((cmd->uhs2_cmd->header & UHS2_NATIVE_PACKET) &&
>>> +	    ((((cmd->uhs2_cmd->arg & 0xF) << 8) |
>>> +	    ((cmd->uhs2_cmd->arg >> 8) & 0xFF)) == UHS2_DEV_CMD_TRANS_ABORT))
>>> +		cmd_reg |= SDHCI_UHS2_COMMAND_TRNS_ABORT;
>>> +
>>> +	/* UHS2 Native DORMANT */
>>> +	if ((cmd->uhs2_cmd->header & UHS2_NATIVE_PACKET) &&
>>> +	    ((((cmd->uhs2_cmd->arg & 0xF) << 8) |
>>> +	     ((cmd->uhs2_cmd->arg >> 8) & 0xFF)) ==
>>> +				UHS2_DEV_CMD_GO_DORMANT_STATE))
>>> +		cmd_reg |= SDHCI_UHS2_COMMAND_DORMANT;
>>> +
>>> +	DBG("0x%x is set to UHS2 CMD register.\n", cmd_reg);
>>> +
>>> +	sdhci_writew(host, cmd_reg, SDHCI_UHS2_COMMAND);
>>> +}
>>> +
>>> +static bool sdhci_uhs2_send_command(struct sdhci_host *host,
>>> +				    struct mmc_command *cmd)
>>> +{
>>> +	int flags;
>>> +	u32 mask;
>>> +	unsigned long timeout;
>>> +
>>> +	/* FIXME: Is this check necessary? */
>>
>> No
> 
> Will drop it.
> 
>>
>>> +	if (!(host->mmc->flags & MMC_UHS2_SUPPORT))
>>> +		return sdhci_send_command(host, cmd);
>>> +
>>> +	WARN_ON(host->cmd);
>>> +
>>> +	/* Initially, a command has no error */
>>> +	cmd->error = 0;
>>> +
>>> +	if ((host->quirks2 & SDHCI_QUIRK2_STOP_WITH_TC) &&
>>
>> Quirk
> 
> Will drop it.
> 
>>
>>> +	    cmd->opcode == MMC_STOP_TRANSMISSION)
>>> +		cmd->flags |= MMC_RSP_BUSY;
>>> +
>>> +	mask = SDHCI_CMD_INHIBIT;
>>> +	if (sdhci_data_line_cmd(cmd))
>>> +		mask |= SDHCI_DATA_INHIBIT;
>>
>> Command inhibit for data is not supported by UHS2
> 
> Will drop it.
> 
>>> +
>>> +	/* We shouldn't wait for data inihibit for stop commands, even
>>> +	   though they might use busy signaling */
>>> +	if (cmd->mrq->data && (cmd == cmd->mrq->data->stop))
>>> +		mask &= ~SDHCI_DATA_INHIBIT;
>>
>> Ditto
> 
> Will drop it.
> 
>>
>>> +
>>> +	if (sdhci_readl(host, SDHCI_PRESENT_STATE) & mask)
>>> +		return false;
>>> +
>>> +	host->cmd = cmd;
>>> +	host->data_timeout = 0;
>>> +	if (sdhci_data_line_cmd(cmd)) {
>>> +		WARN_ON(host->data_cmd);
>>> +		host->data_cmd = cmd;
>>> +		__sdhci_uhs2_set_timeout(host);
>>> +	}
>>> +
>>> +	if (cmd->data) {
>>> +		if (host->use_external_dma)
>>> +			sdhci_uhs2_external_dma_prepare_data(host, cmd);
>>
>> To start with, let's drop support for external DMA with UHS2. i.e. disallow
>> UHS2 mode if external DMA is enabled
> 
> Okay.
> I will add a check against host->use_external in uhs2_do_detect_init().
> 
>>
>>> +		else
>>> +			sdhci_uhs2_prepare_data(host, cmd);
>>> +	}
>>> +
>>> +	sdhci_uhs2_set_transfer_mode(host, cmd);
>>> +
>>> +	if ((cmd->flags & MMC_RSP_136) && (cmd->flags & MMC_RSP_BUSY)) {
>>> +		WARN_ONCE(1, "Unsupported response type!\n");
>>> +		/*
>>> +		 * This does not happen in practice because 136-bit response
>>> +		 * commands never have busy waiting, so rather than complicate
>>> +		 * the error path, just remove busy waiting and continue.
>>> +		 */
>>> +		cmd->flags &= ~MMC_RSP_BUSY;
>>> +	}
>>> +
>>> +	if (!(cmd->flags & MMC_RSP_PRESENT))
>>> +		flags = SDHCI_CMD_RESP_NONE;
>>> +	else if (cmd->flags & MMC_RSP_136)
>>> +		flags = SDHCI_CMD_RESP_LONG;
>>> +	else if (cmd->flags & MMC_RSP_BUSY)
>>> +		flags = SDHCI_CMD_RESP_SHORT_BUSY;
>>> +	else
>>> +		flags = SDHCI_CMD_RESP_SHORT;
>>> +
>>> +	if (cmd->flags & MMC_RSP_CRC)
>>> +		flags |= SDHCI_CMD_CRC;
>>> +	if (cmd->flags & MMC_RSP_OPCODE)
>>> +		flags |= SDHCI_CMD_INDEX;
>>> +
>>> +	/* CMD19 is special in that the Data Present Select should be set */
>>> +	if (cmd->data || cmd->opcode == MMC_SEND_TUNING_BLOCK ||
>>> +	    cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200)
>>
>> No tuning commands fo UHS2
>>
>>> +		flags |= SDHCI_CMD_DATA;
>>
>> flags are never used?
> 
> Good catch. Will drop it.
> 
>>> +
>>> +	timeout = jiffies;
>>> +	if (host->data_timeout)
>>> +		timeout += nsecs_to_jiffies(host->data_timeout);
>>> +	else if (!cmd->data && cmd->busy_timeout > 9000)
>>> +		timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
>>> +	else
>>> +		timeout += 10 * HZ;
>>> +	sdhci_mod_timer(host, cmd->mrq, timeout);
>>> +
>>> +	if (host->use_external_dma)
>>> +		sdhci_external_dma_pre_transfer(host, cmd);
>>> +
>>> +	__sdhci_uhs2_send_command(host, cmd);
>>> +
>>> +	return true;
>>> +}
>>> +
>>> +static bool sdhci_uhs2_send_command_retry(struct sdhci_host *host,
>>> +				     struct mmc_command *cmd,
>>> +				     unsigned long flags)
>>
>> Can probably get rid of sdhci_uhs2_send_command_retry
> 
> Sure
> 
>>> +	__releases(host->lock)
>>> +	__acquires(host->lock)
>>> +{
>>> +	struct mmc_command *deferred_cmd = host->deferred_cmd;
>>> +	int timeout = 10; /* Approx. 10 ms */
>>> +	bool present;
>>> +
>>> +	while (!sdhci_uhs2_send_command(host, cmd)) {
>>> +		if (!timeout--) {
>>> +			pr_err("%s: Controller never released inhibit bit(s).\n",
>>> +			       mmc_hostname(host->mmc));
>>> +			sdhci_dumpregs(host);
>>> +			cmd->error = -EIO;
>>> +			return false;
>>> +		}
>>> +
>>> +		spin_unlock_irqrestore(&host->lock, flags);
>>> +
>>> +		usleep_range(1000, 1250);
>>> +
>>> +		present = host->mmc->ops->get_cd(host->mmc);
>>> +
>>> +		spin_lock_irqsave(&host->lock, flags);
>>> +
>>> +		/* A deferred command might disappear, handle that */
>>> +		if (cmd == deferred_cmd && cmd != host->deferred_cmd)
>>> +			return true;
>>> +
>>> +		if (sdhci_present_error(host, cmd, present))
>>> +			return false;
>>> +	}
>>> +
>>> +	if (cmd == host->deferred_cmd)
>>> +		host->deferred_cmd = NULL;
>>> +
>>> +	return true;
>>> +}
>>> +
>>> +static void __sdhci_uhs2_finish_command(struct sdhci_host *host)
>>> +{
>>> +	struct mmc_command *cmd = host->cmd;
>>> +	u8 resp;
>>> +	u8 ecode;
>>> +	bool bReadA0 = 0;
>>> +	int i;
>>> +
>>> +	if (host->mmc->flags & MMC_UHS2_INITIALIZED) {
>>> +		resp = sdhci_readb(host, SDHCI_UHS2_RESPONSE + 2);
>>> +		if (resp & UHS2_RES_NACK_MASK) {
>>> +			ecode = (resp >> UHS2_RES_ECODE_POS) &
>>> +				UHS2_RES_ECODE_MASK;
>>> +			pr_err("%s: NACK is got, ECODE=0x%x.\n",
>>> +			       mmc_hostname(host->mmc), ecode);
>>> +		}
>>> +		bReadA0 = 1;
>>> +	}
>>> +
>>> +	if (cmd->uhs2_resp &&
>>> +	    cmd->uhs2_resp_len && cmd->uhs2_resp_len <= 20) {
>>> +		/* Get whole response of some native CCMD, like
>>> +		 * DEVICE_INIT, ENUMERATE.
>>> +		 */
>>> +		for (i = 0; i < cmd->uhs2_resp_len; i++)
>>> +			cmd->uhs2_resp[i] =
>>> +				sdhci_readb(host, SDHCI_UHS2_RESPONSE + i);
>>> +	} else {
>>> +		/* Get SD CMD response and Payload for some read
>>> +		 * CCMD, like INQUIRY_CFG.
>>> +		 */
>>> +		/* Per spec (p136), payload field is divided into
>>> +		 * a unit of DWORD and transmission order within
>>> +		 * a DWORD is big endian.
>>> +		 */
>>> +		if (!bReadA0)
>>> +			sdhci_readl(host, SDHCI_UHS2_RESPONSE);
>>> +		for (i = 4; i < 20; i += 4) {
>>> +			cmd->resp[i / 4 - 1] =
>>> +				(sdhci_readb(host,
>>> +					     SDHCI_UHS2_RESPONSE + i) << 24) |
>>> +				(sdhci_readb(host,
>>> +					     SDHCI_UHS2_RESPONSE + i + 1)
>>> +					<< 16) |
>>> +				(sdhci_readb(host,
>>> +					     SDHCI_UHS2_RESPONSE + i + 2)
>>> +					<< 8) |
>>> +				sdhci_readb(host, SDHCI_UHS2_RESPONSE + i + 3);
>>> +		}
>>> +	}
>>> +}
>>> +
>>> +static void sdhci_uhs2_finish_command(struct sdhci_host *host)
>>> +{
>>> +	struct mmc_command *cmd = host->cmd;
>>> +
>>> +	/* FIXME: Is this check necessary? */
>>> +	if (!(host->mmc->flags & MMC_UHS2_SUPPORT)) {
>>> +		sdhci_finish_command(host);
>>> +		return;
>>> +	}
>>> +
>>> +	__sdhci_uhs2_finish_command(host);
>>> +
>>> +	host->cmd = NULL;
>>> +
>>> +	if (cmd->mrq->cap_cmd_during_tfr && cmd == cmd->mrq->cmd)
>>> +		mmc_command_done(host->mmc, cmd->mrq);
>>> +
>>> +	/*
>>> +	 * The host can send and interrupt when the busy state has
>>> +	 * ended, allowing us to wait without wasting CPU cycles.
>>> +	 * The busy signal uses DAT0 so this is similar to waiting
>>> +	 * for data to complete.
>>> +	 *
>>> +	 * Note: The 1.0 specification is a bit ambiguous about this
>>> +	 *       feature so there might be some problems with older
>>> +	 *       controllers.
>>> +	 */
>>> +	if (cmd->flags & MMC_RSP_BUSY) {
>>> +		if (cmd->data) {
>>> +			DBG("Cannot wait for busy signal when also doing a data transfer");
>>> +		} else if (!(host->quirks & SDHCI_QUIRK_NO_BUSY_IRQ) &&
>>> +			   cmd == host->data_cmd) {
>>> +			/* Command complete before busy is ended */
>>> +			return;
>>> +		}
>>> +	}
>>> +
>>> +	/* Finished CMD23, now send actual command. */
>>
>> UHS2 doesn't use CMD23 does it?
> 
> Should we remove any code in this function, other than this comment?

We should be able to assume (cmd != cmd->mrq->sbc) is always true because
sbc is never used.

> 
> -Takahiro Akashi
> 
>>> +	if (cmd == cmd->mrq->sbc) {
>>> +		if (!sdhci_uhs2_send_command(host, cmd->mrq->cmd)) {
>>> +			WARN_ON(host->deferred_cmd);
>>> +			host->deferred_cmd = cmd->mrq->cmd;
>>> +		}
>>> +	} else {
>>> +
>>> +		/* Processed actual command. */
>>> +		if (host->data && host->data_early)
>>> +			sdhci_uhs2_finish_data(host);
>>> +
>>> +		if (!cmd->data)
>>> +			__sdhci_finish_mrq(host, cmd->mrq);
>>> +	}
>>> +}
>>> +
>>>  /*****************************************************************************\
>>>   *                                                                           *
>>>   * Driver init/exit                                                          *
>>> @@ -691,6 +1219,7 @@ static int sdhci_uhs2_host_ops_init(struct sdhci_host *host)
>>>  	host->mmc_host_ops.start_signal_voltage_switch =
>>>  		sdhci_uhs2_start_signal_voltage_switch;
>>>  	host->mmc_host_ops.set_ios = sdhci_uhs2_set_ios;
>>> +	host->mmc_host_ops.request = sdhci_uhs2_request;
>>>  
>>>  	if (!host->mmc_host_ops.uhs2_detect_init)
>>>  		host->mmc_host_ops.uhs2_detect_init = sdhci_uhs2_do_detect_init;
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index becb228330af..a9f5449bddcc 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -48,8 +48,6 @@
>>>  static unsigned int debug_quirks = 0;
>>>  static unsigned int debug_quirks2;
>>>  
>>> -static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd);
>>> -
>>>  void sdhci_dumpregs(struct sdhci_host *host)
>>>  {
>>>  	SDHCI_DUMP("============ SDHCI REGISTER DUMP ===========\n");
>>> @@ -148,10 +146,13 @@ void sdhci_enable_v4_mode(struct sdhci_host *host)
>>>  }
>>>  EXPORT_SYMBOL_GPL(sdhci_enable_v4_mode);
>>>  
>>> -static inline bool sdhci_data_line_cmd(struct mmc_command *cmd)
>>> +bool sdhci_data_line_cmd(struct mmc_command *cmd)
>>>  {
>>>  	return cmd->data || cmd->flags & MMC_RSP_BUSY;
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_data_line_cmd);
>>> +
>>> +/* TODO: move this as an inline function to a header */
>>>  
>>>  static void sdhci_set_card_detection(struct sdhci_host *host, bool enable)
>>>  {
>>> @@ -363,7 +364,7 @@ static void sdhci_reinit(struct sdhci_host *host)
>>>  		mmc_detect_change(host->mmc, msecs_to_jiffies(200));
>>>  }
>>>  
>>> -static void __sdhci_led_activate(struct sdhci_host *host)
>>> +void __sdhci_led_activate(struct sdhci_host *host)
>>>  {
>>>  	u8 ctrl;
>>>  
>>> @@ -374,8 +375,9 @@ static void __sdhci_led_activate(struct sdhci_host *host)
>>>  	ctrl |= SDHCI_CTRL_LED;
>>>  	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>>>  }
>>> +EXPORT_SYMBOL_GPL(__sdhci_led_activate);
>>>  
>>> -static void __sdhci_led_deactivate(struct sdhci_host *host)
>>> +void __sdhci_led_deactivate(struct sdhci_host *host)
>>>  {
>>>  	u8 ctrl;
>>>  
>>> @@ -386,6 +388,7 @@ static void __sdhci_led_deactivate(struct sdhci_host *host)
>>>  	ctrl &= ~SDHCI_CTRL_LED;
>>>  	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>>>  }
>>> +EXPORT_SYMBOL_GPL(__sdhci_led_deactivate);
>>>  
>>>  #if IS_REACHABLE(CONFIG_LEDS_CLASS)
>>>  static void sdhci_led_control(struct led_classdev *led,
>>> @@ -464,14 +467,15 @@ static inline void sdhci_led_deactivate(struct sdhci_host *host)
>>>  
>>>  #endif
>>>  
>>> -static void sdhci_mod_timer(struct sdhci_host *host, struct mmc_request *mrq,
>>> -			    unsigned long timeout)
>>> +void sdhci_mod_timer(struct sdhci_host *host, struct mmc_request *mrq,
>>> +		     unsigned long timeout)
>>>  {
>>>  	if (sdhci_data_line_cmd(mrq->cmd))
>>>  		mod_timer(&host->data_timer, timeout);
>>>  	else
>>>  		mod_timer(&host->timer, timeout);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_mod_timer);
>>>  
>>>  static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)
>>>  {
>>> @@ -1043,8 +1047,7 @@ static void sdhci_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>>>  		__sdhci_set_timeout(host, cmd);
>>>  }
>>>  
>>> -static void sdhci_initialize_data(struct sdhci_host *host,
>>> -				  struct mmc_data *data)
>>> +void sdhci_initialize_data(struct sdhci_host *host, struct mmc_data *data)
>>>  {
>>>  	WARN_ON(host->data);
>>>  
>>> @@ -1057,6 +1060,7 @@ static void sdhci_initialize_data(struct sdhci_host *host,
>>>  	host->data_early = 0;
>>>  	host->data->bytes_xfered = 0;
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_initialize_data);
>>>  
>>>  static inline void sdhci_set_block_info(struct sdhci_host *host,
>>>  					struct mmc_data *data)
>>> @@ -1079,12 +1083,8 @@ static inline void sdhci_set_block_info(struct sdhci_host *host,
>>>  	}
>>>  }
>>>  
>>> -static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
>>> +void sdhci_prepare_dma(struct sdhci_host *host, struct mmc_data *data)
>>>  {
>>> -	struct mmc_data *data = cmd->data;
>>> -
>>> -	sdhci_initialize_data(host, data);
>>> -
>>>  	if (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA)) {
>>>  		struct scatterlist *sg;
>>>  		unsigned int length_mask, offset_mask;
>>> @@ -1169,6 +1169,16 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
>>>  	}
>>>  
>>>  	sdhci_set_transfer_irqs(host);
>>> +}
>>> +EXPORT_SYMBOL_GPL(sdhci_prepare_dma);
>>> +
>>> +static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
>>> +{
>>> +	struct mmc_data *data = cmd->data;
>>> +
>>> +	sdhci_initialize_data(host, data);
>>> +
>>> +	sdhci_prepare_dma(host, data);
>>>  
>>>  	sdhci_set_block_info(host, data);
>>>  }
>>> @@ -1211,8 +1221,7 @@ static struct dma_chan *sdhci_external_dma_channel(struct sdhci_host *host,
>>>  	return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;
>>>  }
>>>  
>>> -static int sdhci_external_dma_setup(struct sdhci_host *host,
>>> -				    struct mmc_command *cmd)
>>> +int sdhci_external_dma_setup(struct sdhci_host *host, struct mmc_command *cmd)
>>>  {
>>>  	int ret, i;
>>>  	enum dma_transfer_direction dir;
>>> @@ -1264,8 +1273,9 @@ static int sdhci_external_dma_setup(struct sdhci_host *host,
>>>  
>>>  	return ret;
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_external_dma_setup);
>>>  
>>> -static void sdhci_external_dma_release(struct sdhci_host *host)
>>> +void sdhci_external_dma_release(struct sdhci_host *host)
>>>  {
>>>  	if (host->tx_chan) {
>>>  		dma_release_channel(host->tx_chan);
>>> @@ -1279,9 +1289,10 @@ static void sdhci_external_dma_release(struct sdhci_host *host)
>>>  
>>>  	sdhci_switch_external_dma(host, false);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_external_dma_release);
>>>  
>>> -static void __sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>> -					      struct mmc_command *cmd)
>>> +void __sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>> +				       struct mmc_command *cmd)
>>>  {
>>>  	struct mmc_data *data = cmd->data;
>>>  
>>> @@ -1292,6 +1303,7 @@ static void __sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>>  
>>>  	sdhci_set_block_info(host, data);
>>>  }
>>> +EXPORT_SYMBOL(__sdhci_external_dma_prepare_data);
>>>  
>>>  static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>>  					    struct mmc_command *cmd)
>>> @@ -1306,8 +1318,8 @@ static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>>  	}
>>>  }
>>>  
>>> -static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
>>> -					    struct mmc_command *cmd)
>>> +void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
>>> +				     struct mmc_command *cmd)
>>>  {
>>>  	struct dma_chan *chan;
>>>  
>>> @@ -1318,6 +1330,7 @@ static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
>>>  	if (chan)
>>>  		dma_async_issue_pending(chan);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_external_dma_pre_transfer);
>>>  
>>>  #else
>>>  
>>> @@ -1369,11 +1382,11 @@ static inline bool sdhci_auto_cmd23(struct sdhci_host *host,
>>>  	return mrq->sbc && (host->flags & SDHCI_AUTO_CMD23);
>>>  }
>>>  
>>> -static inline bool sdhci_manual_cmd23(struct sdhci_host *host,
>>> -				      struct mmc_request *mrq)
>>> +bool sdhci_manual_cmd23(struct sdhci_host *host, struct mmc_request *mrq)
>>>  {
>>>  	return mrq->sbc && !(host->flags & SDHCI_AUTO_CMD23);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_manual_cmd23);
>>>  
>>>  static inline void sdhci_auto_cmd_select(struct sdhci_host *host,
>>>  					 struct mmc_command *cmd,
>>> @@ -1483,7 +1496,7 @@ static void sdhci_set_mrq_done(struct sdhci_host *host, struct mmc_request *mrq)
>>>  	WARN_ON(i >= SDHCI_MAX_MRQS);
>>>  }
>>>  
>>> -static void __sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq)
>>> +void __sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq)
>>>  {
>>>  	if (host->cmd && host->cmd->mrq == mrq)
>>>  		host->cmd = NULL;
>>> @@ -1507,15 +1520,17 @@ static void __sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq)
>>>  	if (!sdhci_has_requests(host))
>>>  		sdhci_led_deactivate(host);
>>>  }
>>> +EXPORT_SYMBOL_GPL(__sdhci_finish_mrq);
>>>  
>>> -static void sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq)
>>> +void sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq)
>>>  {
>>>  	__sdhci_finish_mrq(host, mrq);
>>>  
>>>  	queue_work(host->complete_wq, &host->complete_work);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_finish_mrq);
>>>  
>>> -static void __sdhci_finish_data(struct sdhci_host *host, bool sw_data_timeout)
>>> +void __sdhci_finish_data_common(struct sdhci_host *host)
>>>  {
>>>  	struct mmc_command *data_cmd = host->data_cmd;
>>>  	struct mmc_data *data = host->data;
>>> @@ -1548,6 +1563,14 @@ static void __sdhci_finish_data(struct sdhci_host *host, bool sw_data_timeout)
>>>  		data->bytes_xfered = 0;
>>>  	else
>>>  		data->bytes_xfered = data->blksz * data->blocks;
>>> +}
>>> +EXPORT_SYMBOL_GPL(__sdhci_finish_data_common);
>>> +
>>> +static void __sdhci_finish_data(struct sdhci_host *host, bool sw_data_timeout)
>>> +{
>>> +	struct mmc_data *data = host->data;
>>> +
>>> +	__sdhci_finish_data_common(host);
>>>  
>>>  	/*
>>>  	 * Need to send CMD12 if -
>>> @@ -1586,12 +1609,13 @@ static void __sdhci_finish_data(struct sdhci_host *host, bool sw_data_timeout)
>>>  	}
>>>  }
>>>  
>>> -static void sdhci_finish_data(struct sdhci_host *host)
>>> +void sdhci_finish_data(struct sdhci_host *host)
>>>  {
>>>  	__sdhci_finish_data(host, false);
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_finish_data);
>>>  
>>> -static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>>> +bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>>>  {
>>>  	int flags;
>>>  	u32 mask;
>>> @@ -1633,8 +1657,6 @@ static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>>>  			sdhci_prepare_data(host, cmd);
>>>  	}
>>>  
>>> -	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
>>> -
>>>  	sdhci_set_transfer_mode(host, cmd);
>>>  
>>>  	if ((cmd->flags & MMC_RSP_136) && (cmd->flags & MMC_RSP_BUSY)) {
>>> @@ -1678,13 +1700,16 @@ static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>>>  	if (host->use_external_dma)
>>>  		sdhci_external_dma_pre_transfer(host, cmd);
>>>  
>>> +	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
>>> +
>>>  	sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);
>>>  
>>>  	return true;
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_send_command);
>>>  
>>> -static bool sdhci_present_error(struct sdhci_host *host,
>>> -				struct mmc_command *cmd, bool present)
>>> +bool sdhci_present_error(struct sdhci_host *host,
>>> +			 struct mmc_command *cmd, bool present)
>>>  {
>>>  	if (!present || host->flags & SDHCI_DEVICE_DEAD) {
>>>  		cmd->error = -ENOMEDIUM;
>>> @@ -1693,6 +1718,7 @@ static bool sdhci_present_error(struct sdhci_host *host,
>>>  
>>>  	return false;
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_present_error);
>>>  
>>>  static bool sdhci_send_command_retry(struct sdhci_host *host,
>>>  				     struct mmc_command *cmd,
>>> @@ -1755,7 +1781,7 @@ static void sdhci_read_rsp_136(struct sdhci_host *host, struct mmc_command *cmd)
>>>  	}
>>>  }
>>>  
>>> -static void sdhci_finish_command(struct sdhci_host *host)
>>> +void sdhci_finish_command(struct sdhci_host *host)
>>>  {
>>>  	struct mmc_command *cmd = host->cmd;
>>>  
>>> @@ -1808,6 +1834,7 @@ static void sdhci_finish_command(struct sdhci_host *host)
>>>  			__sdhci_finish_mrq(host, cmd->mrq);
>>>  	}
>>>  }
>>> +EXPORT_SYMBOL_GPL(sdhci_finish_command);
>>>  
>>>  static u16 sdhci_get_preset_value(struct sdhci_host *host)
>>>  {
>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>> index e84ebddb20d8..6eeb74741da3 100644
>>> --- a/drivers/mmc/host/sdhci.h
>>> +++ b/drivers/mmc/host/sdhci.h
>>> @@ -831,8 +831,29 @@ static inline void sdhci_read_caps(struct sdhci_host *host)
>>>  	__sdhci_read_caps(host, NULL, NULL, NULL);
>>>  }
>>>  
>>> +bool sdhci_data_line_cmd(struct mmc_command *cmd);
>>>  void sdhci_runtime_pm_bus_on(struct sdhci_host *host);
>>>  void sdhci_runtime_pm_bus_off(struct sdhci_host *host);
>>> +void sdhci_mod_timer(struct sdhci_host *host, struct mmc_request *mrq,
>>> +                     unsigned long timeout);
>>> +void sdhci_initialize_data(struct sdhci_host *host, struct mmc_data *data);
>>> +void sdhci_prepare_dma(struct sdhci_host *host, struct mmc_data *data);
>>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
>>> +int sdhci_external_dma_setup(struct sdhci_host *host, struct mmc_command *cmd);
>>> +void sdhci_external_dma_release(struct sdhci_host *host);
>>> +void __sdhci_external_dma_prepare_data(struct sdhci_host *host,
>>> +                                       struct mmc_command *cmd);
>>> +void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
>>> +                                     struct mmc_command *cmd);
>>> +#endif
>>> +bool sdhci_manual_cmd23(struct sdhci_host *host, struct mmc_request *mrq);
>>> +void __sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq);
>>> +void sdhci_finish_mrq(struct sdhci_host *host, struct mmc_request *mrq);
>>> +void __sdhci_finish_data_common(struct sdhci_host *host);
>>> +bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd);
>>> +void sdhci_finish_command(struct sdhci_host *host);
>>> +bool sdhci_present_error(struct sdhci_host *host,
>>> +                         struct mmc_command *cmd, bool present);
>>>  u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
>>>  		   unsigned int *actual_clock);
>>>  void sdhci_set_clock(struct sdhci_host *host, unsigned int clock);
>>>
>>