RE: [PATCH] mmc: core: Add cache control for eMMC4.5 device

[Seungwon Jeon <tgih.jun@samsung.com>]

Adrian Hunter wrote:
> On 08/09/11 10:29, Seungwon Jeon wrote:
> > This patch adds cache feature of eMMC4.5 Spec.
> > If device supports cache capability, host can utilize some specific
> > operations.
> >
> > Signed-off-by: Seungwon Jeon<tgih.jun@samsung.com>
> > ---
> > This patch is base on [PATCH v3] mmc: core: Add default timeout value
> for CMD6
> >
> >   drivers/mmc/card/block.c |   14 ++++++----
> >   drivers/mmc/core/core.c  |   62
> ++++++++++++++++++++++++++++++++++++++++++++++
> >   drivers/mmc/core/mmc.c   |   23 +++++++++++++++++
> >   include/linux/mmc/card.h |    2 +
> >   include/linux/mmc/core.h |    2 +
> >   include/linux/mmc/host.h |    3 ++
> >   include/linux/mmc/mmc.h  |    3 ++
> >   7 files changed, 103 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> > index e702c61..84fa4bb 100644
> > --- a/drivers/mmc/card/block.c
> > +++ b/drivers/mmc/card/block.c
> > @@ -779,16 +779,18 @@ out:
> >   static int mmc_blk_issue_flush(struct mmc_queue *mq, struct request
> *req)
> >   {
> >   	struct mmc_blk_data *md = mq->data;
> > +	struct mmc_card *card = md->queue.card;
> > +	int ret = 0;
> > +
> > +	ret = mmc_flush_cache(card);
> > +	if (ret)
> > +		ret = -EIO;
> >
> > -	/*
> > -	 * No-op, only service this because we need REQ_FUA for reliable
> > -	 * writes.
> > -	 */
> >   	spin_lock_irq(&md->lock);
> > -	__blk_end_request_all(req, 0);
> > +	__blk_end_request_all(req, ret);
> >   	spin_unlock_irq(&md->lock);
> >
> > -	return 1;
> > +	return ret ? 0 : 1;
> >   }
> >
> >   /*
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index 557856b..14c2431 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -1987,6 +1987,64 @@ int mmc_card_can_sleep(struct mmc_host *host)
> >   }
> >   EXPORT_SYMBOL(mmc_card_can_sleep);
> >
> > +/*
> > + * Flush the cache to the non-volatile storage.
> > + */
> > +int mmc_flush_cache(struct mmc_card *card)
> > +{
> > +	struct mmc_host *host = card->host;
> > +	int err = 0;
> > +
> > +	if (!(host->caps&  MMC_CAP_CACHE_CTRL))
> > +		return err;
> > +
> > +	if (mmc_card_mmc(card)&&
> > +			(card->ext_csd.cache_size>  0)&&
> > +			(card->ext_csd.cache_ctrl&  1)) {
> > +		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > +				EXT_CSD_FLUSH_CACHE, 1, 0);
> > +		if (err)
> > +			pr_err("%s: cache flush error %d\n",
> > +					mmc_hostname(card->host), err);
> > +	}
> > +
> > +	return err;
> > +}
> > +EXPORT_SYMBOL(mmc_flush_cache);
> > +
> > +/*
> > + * Turn the cache ON/OFF.
> > + * Turning the cache OFF shall trigger flushing of the data
> > + * to the non-volatile storage.
> > + */
> > +int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
> > +{
> > +	struct mmc_card *card = host->card;
> > +	int err = 0;
> > +
> > +	if (!(host->caps&  MMC_CAP_CACHE_CTRL))
> > +		return err;
> > +
> 
> This patch does not cover code paths for removable cards.
> For clarity and in case a platform does not set non-removable
> flags for eMMC, a check is needed here e.g.
> 
> 	if (mmc_card_is_removable(host))
> 		return 0;
> 
Is it worry about normal MMC card type and?
Then, "card->ext_csd.cache_size" is a good condition for deciding cache control.
Or even though eMMC should be non-removable type, platform does not set non-removable for eMMC type mistakenly?
I can't catch the meaning exactly.
Please let me know.

Thanks.
Beset regards,
Seungwon Jeon.

> > +	if (card&&  mmc_card_mmc(card)&&
> > +			(card->ext_csd.cache_size>  0)) {
> > +		enable = !!enable;
> > +
> > +		if (card->ext_csd.cache_ctrl ^ enable)
> > +			err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > +					EXT_CSD_CACHE_CTRL, enable, 0);
> > +		if (err)
> > +			pr_err("%s: cache %s error %d\n",
> > +					mmc_hostname(card->host),
> > +					enable ? "on" : "off",
> > +					err);
> > +		else
> > +			card->ext_csd.cache_ctrl = enable;
> > +	}
> > +
> > +	return err;
> > +}
> > +EXPORT_SYMBOL(mmc_cache_ctrl);
> > +
> >   #ifdef CONFIG_PM
> >
> >   /**
> > @@ -2001,6 +2059,9 @@ int mmc_suspend_host(struct mmc_host *host)
> >   		cancel_delayed_work(&host->disable);
> >   	cancel_delayed_work(&host->detect);
> >   	mmc_flush_scheduled_work();
> > +	err = mmc_cache_ctrl(host, 0);
> > +	if (err)
> > +		goto out;
> >
> >   	mmc_bus_get(host);
> >   	if (host->bus_ops&&  !host->bus_dead) {
> > @@ -2025,6 +2086,7 @@ int mmc_suspend_host(struct mmc_host *host)
> >   	if (!err&&  !mmc_card_keep_power(host))
> >   		mmc_power_off(host);
> >
> > +out:
> >   	return err;
> >   }
> >
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index ea58a0c..035112b 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -419,6 +419,12 @@ static int mmc_read_ext_csd(struct mmc_card *card,
> u8 *ext_csd)
> >   		 */
> >   		card->ext_csd.generic_cmd6_time = 0;
> >
> > +	card->ext_csd.cache_size =
> > +		ext_csd[EXT_CSD_CACHE_SIZE + 0]<<  0 |
> > +		ext_csd[EXT_CSD_CACHE_SIZE + 1]<<  8 |
> > +		ext_csd[EXT_CSD_CACHE_SIZE + 2]<<  16 |
> > +		ext_csd[EXT_CSD_CACHE_SIZE + 3]<<  24;
> > +
> >   out:
> >   	return err;
> >   }
> > @@ -851,6 +857,23 @@ static int mmc_init_card(struct mmc_host *host, u32
> ocr,
> >   		}
> >   	}
> >
> > +	/*
> > +	 * If cache size is higher than 0, this indicates
> > +	 * the the existence of cache and it can be turned on.
> > +	 */
> > +	if ((host->caps&  MMC_CAP_CACHE_CTRL)&&
> > +			card->ext_csd.cache_size>  0) {
> > +		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > +				EXT_CSD_CACHE_CTRL, 1, 0);
> > +		if (err&&  err != -EBADMSG)
> > +			goto free_card;
> > +
> > +		/*
> > +		 * Only if no error, cache is turned on successfully.
> > +		 */
> > +		card->ext_csd.cache_ctrl = err ? 0 : 1;
> > +	}
> > +
> >   	if (!oldcard)
> >   		host->card = card;
> >
> > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> > index b713abf..519660b 100644
> > --- a/include/linux/mmc/card.h
> > +++ b/include/linux/mmc/card.h
> > @@ -50,6 +50,7 @@ struct mmc_ext_csd {
> >   	u8			rel_sectors;
> >   	u8			rel_param;
> >   	u8			part_config;
> > +	u8			cache_ctrl;
> >   	unsigned int		part_time;		/* Units: ms */
> >   	unsigned int		sa_timeout;		/* Units: 100ns */
> >   	unsigned int		generic_cmd6_time;	/* Units: 10ms */
> > @@ -65,6 +66,7 @@ struct mmc_ext_csd {
> >   	unsigned long long	enhanced_area_offset;	/* Units: Byte */
> >   	unsigned int		enhanced_area_size;	/* Units: KB */
> >   	unsigned int		boot_size;		/* in bytes */
> > +	unsigned int		cache_size;		/* Units: KB */
> >   	u8			raw_partition_support;	/* 160 */
> >   	u8			raw_erased_mem_count;	/* 181 */
> >   	u8			raw_ext_csd_structure;	/* 194 */
> > diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> > index b8b1b7a..45b4acf 100644
> > --- a/include/linux/mmc/core.h
> > +++ b/include/linux/mmc/core.h
> > @@ -171,6 +171,8 @@ extern void mmc_release_host(struct mmc_host *host);
> >   extern void mmc_do_release_host(struct mmc_host *host);
> >   extern int mmc_try_claim_host(struct mmc_host *host);
> >
> > +extern int mmc_flush_cache(struct mmc_card *);
> > +
> >   /**
> >    *	mmc_claim_host - exclusively claim a host
> >    *	@host: mmc host to claim
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index 4c4bddf..6d0006d 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -230,6 +230,7 @@ struct mmc_host {
> >   #define MMC_CAP_MAX_CURRENT_600	(1<<  28)	/* Host max current
> limit is 600mA */
> >   #define MMC_CAP_MAX_CURRENT_800	(1<<  29)	/* Host max current
> limit is 800mA */
> >   #define MMC_CAP_CMD23		(1<<  30)	/* CMD23 supported. */
> > +#define MMC_CAP_CACHE_CTRL		(1<<  31)	/* Allow cache
> control. */
> >
> >   	mmc_pm_flag_t		pm_caps;	/* supported pm features */
> >
> > @@ -335,6 +336,8 @@ extern int mmc_power_restore_host(struct mmc_host
> *host);
> >   extern void mmc_detect_change(struct mmc_host *, unsigned long delay);
> >   extern void mmc_request_done(struct mmc_host *, struct mmc_request *);
> >
> > +extern int mmc_cache_ctrl(struct mmc_host *, u8);
> > +
> >   static inline void mmc_signal_sdio_irq(struct mmc_host *host)
> >   {
> >   	host->ops->enable_sdio_irq(host, 0);
> > diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
> > index e869f00..b7fa9f7 100644
> > --- a/include/linux/mmc/mmc.h
> > +++ b/include/linux/mmc/mmc.h
> > @@ -270,6 +270,8 @@ struct _mmc_csd {
> >    * EXT_CSD fields
> >    */
> >
> > +#define EXT_CSD_FLUSH_CACHE		32	/* W */
> > +#define EXT_CSD_CACHE_CTRL		33	/* R/W */
> >   #define EXT_CSD_PARTITION_ATTRIBUTE	156	/* R/W */
> >   #define EXT_CSD_PARTITION_SUPPORT	160	/* RO */
> >   #define EXT_CSD_WR_REL_PARAM		166	/* RO */
> > @@ -294,6 +296,7 @@ struct _mmc_csd {
> >   #define EXT_CSD_SEC_FEATURE_SUPPORT	231	/* RO */
> >   #define EXT_CSD_TRIM_MULT		232	/* RO */
> >   #define EXT_CSD_GENERIC_CMD6_TIME	248	/* RO */
> > +#define EXT_CSD_CACHE_SIZE		249	/* RO, 4 bytes */
> >
> >   /*
> >    * EXT_CSD field definitions
> > --
> > 1.7.0.4
> >
> > --
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