Date:	Mon,  6 Jun 2016 11:07:19 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Adrian Hunter <adrian.hunter@...el.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Doug Anderson <dianders@...omium.org>,
	linux-rockchip@...ts.infradead.org,
	Shawn Lin <shawn.lin@...k-chips.com>
Subject: [PATCH] mmc: core: add auto bkops support

JEDEC eMMC v5.1 introduce an autonomously initiated method
for background operations.

Host that wants to enable the device to perform background
operations during device idle time, should signal the device
by setting AUTO_EN in BKOPS_EN field EXT_CSD[163] to 1b. When
this bit is set, the device may start or stop background operations
whenever it sees fit, without any notification to the host.

When AUTO_EN bit is set, the host should keep the device power
active. The host may set or clear this bit at any time based on
its power constraints or other considerations.

Currently the manual bkops is only be used under the async req
circumstances and it's a bit complicated to be controlled as the
perfect method is that we should do some idle monitor just as rpm
and send HPI each time if receiving rd/wr req. But it will impact
performance significantly, especially for random iops since the
weight of executing HPI against r/w small piece of LBAs is
nonnegligible.

So we now prefer to select the auto one unconditionally if supported
which makes it as simple as possible. It should really good enough
for devices to manage its internal policy for bkops rather than the
host, which makes us believe that we could achieve the best
performance for all the devices implementing auto bkops and the only
thing we should do is to disable it when cutting off the power.

Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
---

 drivers/mmc/core/core.c  | 127 +++++++++++++++++++++++++++++++++++++----------
 drivers/mmc/core/mmc.c   |  30 ++++++++++-
 include/linux/mmc/card.h |   1 +
 include/linux/mmc/core.h |   4 +-
 include/linux/mmc/mmc.h  |   1 +
 5 files changed, 133 insertions(+), 30 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index e864187..c2e5a66 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -297,24 +297,13 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
 	return 0;
 }
 
-/**
- *	mmc_start_bkops - start BKOPS for supported cards
- *	@card: MMC card to start BKOPS
- *	@form_exception: A flag to indicate if this function was
- *			 called due to an exception raised by the card
- *
- *	Start background operations whenever requested.
- *	When the urgent BKOPS bit is set in a R1 command response
- *	then background operations should be started immediately.
-*/
-void mmc_start_bkops(struct mmc_card *card, bool from_exception)
+static void  mmc_start_man_bkops(struct mmc_card *card,
+				 bool from_exception)
 {
 	int err;
 	int timeout;
 	bool use_busy_signal;
 
-	BUG_ON(!card);
-
 	if (!card->ext_csd.man_bkops_en || mmc_card_doing_bkops(card))
 		return;
 
@@ -347,7 +336,7 @@ void mmc_start_bkops(struct mmc_card *card, bool from_exception)
 			EXT_CSD_BKOPS_START, 1, timeout,
 			use_busy_signal, true, false);
 	if (err) {
-		pr_warn("%s: Error %d starting bkops\n",
+		pr_warn("%s: Error %d starting manual bkops\n",
 			mmc_hostname(card->host), err);
 		mmc_retune_release(card->host);
 		goto out;
@@ -365,6 +354,55 @@ void mmc_start_bkops(struct mmc_card *card, bool from_exception)
 out:
 	mmc_release_host(card->host);
 }
+
+static void  mmc_start_auto_bkops(struct mmc_card *card)
+{
+	int err;
+
+	/* If it's already enable auto_bkops, nothing to do */
+	if (card->ext_csd.auto_bkops_en)
+		return;
+
+	mmc_claim_host(card->host);
+
+	mmc_retune_hold(card->host);
+
+	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			EXT_CSD_BKOPS_EN, 2,
+			card->ext_csd.generic_cmd6_time);
+	if (err)
+		pr_warn("%s: Error %d starting auto bkops\n",
+			mmc_hostname(card->host), err);
+
+	card->ext_csd.auto_bkops_en = true;
+	mmc_card_set_doing_bkops(card);
+	mmc_retune_release(card->host);
+	mmc_release_host(card->host);
+}
+
+
+/**
+ *	mmc_start_bkops - start BKOPS for supported cards
+ *	@card: MMC card to start BKOPS
+ *	@form_exception: A flag to indicate if this function was
+ *			 called due to an exception raised by the card
+ *          @is_auto: A flag to indicate if we should use auto bkops
+ *
+ *	Start background operations whenever requested.
+ *	When the urgent BKOPS bit is set in a R1 command response
+ *	then background operations should be started immediately, which is
+ *	only needed for man_bkops.
+*/
+void mmc_start_bkops(struct mmc_card *card, bool from_exception,
+		     bool is_auto)
+{
+	BUG_ON(!card);
+
+	if (is_auto)
+		return mmc_start_auto_bkops(card);
+	else
+		return mmc_start_man_bkops(card, from_exception);
+}
 EXPORT_SYMBOL(mmc_start_bkops);
 
 /*
@@ -610,7 +648,9 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
 			if (areq)
 				mmc_post_req(host, areq->mrq, -EINVAL);
 
-			mmc_start_bkops(host->card, true);
+			/* Prefer to use auto bkops for eMMC 5.1 or later */
+			mmc_start_bkops(host->card, true,
+					host->card->ext_csd.rev >= 8);
 
 			/* prepare the request again */
 			if (areq)
@@ -751,20 +791,10 @@ int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd, int retries
 
 EXPORT_SYMBOL(mmc_wait_for_cmd);
 
-/**
- *	mmc_stop_bkops - stop ongoing BKOPS
- *	@card: MMC card to check BKOPS
- *
- *	Send HPI command to stop ongoing background operations to
- *	allow rapid servicing of foreground operations, e.g. read/
- *	writes. Wait until the card comes out of the programming state
- *	to avoid errors in servicing read/write requests.
- */
-int mmc_stop_bkops(struct mmc_card *card)
+static int mmc_stop_man_bkops(struct mmc_card *card)
 {
 	int err = 0;
 
-	BUG_ON(!card);
 	err = mmc_interrupt_hpi(card);
 
 	/*
@@ -779,6 +809,51 @@ int mmc_stop_bkops(struct mmc_card *card)
 
 	return err;
 }
+
+static int mmc_stop_auto_bkops(struct mmc_card *card)
+{
+	int err = 0;
+
+	if (!card->ext_csd.auto_bkops_en)
+		return 0;
+
+	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			EXT_CSD_BKOPS_EN, 0, MMC_BKOPS_MAX_TIMEOUT,
+			true, true, false);
+	if (err)
+		pr_warn("%s: Error %d stoping auto bkops\n",
+			mmc_hostname(card->host), err);
+
+	card->ext_csd.auto_bkops_en = false;
+	mmc_card_clr_doing_bkops(card);
+	mmc_retune_release(card->host);
+
+	return err;
+}
+
+/**
+ *	mmc_stop_bkops - stop ongoing BKOPS
+ *	@card: MMC card to check BKOPS
+ *	@is_auto: A flag to indicate if we should use auto bkops
+ *
+ *	Send HPI command to stop ongoing background operations to
+ *	allow rapid servicing of foreground operations, e.g. read/
+ *	writes. Wait until the card comes out of the programming state
+ *	to avoid errors in servicing read/write requests.
+ *
+ *	But for auto bkops, we could only disable AUTO_EN instead of
+ *	sending HPI. And the firmware could do it automatically.
+ *
+ */
+int mmc_stop_bkops(struct mmc_card *card, bool is_auto)
+{
+	BUG_ON(!card);
+
+	if (is_auto)
+		return mmc_stop_auto_bkops(card);
+	else
+		return mmc_stop_man_bkops(card);
+}
 EXPORT_SYMBOL(mmc_stop_bkops);
 
 int mmc_read_bkops_status(struct mmc_card *card)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 61d6b34..c65bea7 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -508,6 +508,13 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 		/* check whether the eMMC card supports BKOPS */
 		if (ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1) {
 			card->ext_csd.bkops = 1;
+
+			/* for eMMC v5.1 or later, we could use auto_bkops */
+			if (card->ext_csd.rev >= 8)
+				card->ext_csd.auto_bkops_en =
+					(ext_csd[EXT_CSD_BKOPS_EN] &
+						EXT_CSD_AUTO_BKOPS_MASK);
+
 			card->ext_csd.man_bkops_en =
 					(ext_csd[EXT_CSD_BKOPS_EN] &
 						EXT_CSD_MANUAL_BKOPS_MASK);
@@ -516,6 +523,9 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 			if (!card->ext_csd.man_bkops_en)
 				pr_debug("%s: MAN_BKOPS_EN bit is not set\n",
 					mmc_hostname(card->host));
+			if (!card->ext_csd.auto_bkops_en)
+				pr_debug("%s: AUTO_BKOPS_EN bit is not set\n",
+					mmc_hostname(card->host));
 		}
 
 		/* check whether the eMMC card supports HPI */
@@ -1241,7 +1251,7 @@ static int mmc_select_hs400es(struct mmc_card *card)
 	}
 
 	err = mmc_select_bus_width(card);
-	if (IS_ERR_VALUE(err))
+	if (err < 0)
 		goto out_err;
 
 	/* Switch card to HS mode */
@@ -1676,6 +1686,21 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 	mmc_select_powerclass(card);
 
 	/*
+	 * Enable auto bkops feature which is mandatory for
+	 * eMMC v5.1 or later
+	 */
+	if (card->ext_csd.rev >= 8) {
+		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_BKOPS_EN, 2,
+				 card->ext_csd.generic_cmd6_time);
+		if (err)
+			pr_warn("%s: Error %d starting auto bkops\n",
+				mmc_hostname(card->host), err);
+
+		card->ext_csd.auto_bkops_en = true;
+	}
+
+	/*
 	 * Enable HPI feature (if supported)
 	 */
 	if (card->ext_csd.hpi) {
@@ -1898,7 +1923,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 		goto out;
 
 	if (mmc_card_doing_bkops(host->card)) {
-		err = mmc_stop_bkops(host->card);
+		err = mmc_stop_bkops(host->card,
+				     host->card->ext_csd.rev >= 8);
 		if (err)
 			goto out;
 	}
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 22defc2..f82f9be 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -84,6 +84,7 @@ struct mmc_ext_csd {
 	unsigned int		hpi_cmd;		/* cmd used as HPI */
 	bool			bkops;		/* background support bit */
 	bool			man_bkops_en;	/* manual bkops enable bit */
+	bool			auto_bkops_en;	/* auto bkops enbale bit */
 	unsigned int            data_sector_size;       /* 512 bytes or 4KB */
 	unsigned int            data_tag_unit_size;     /* DATA TAG UNIT size */
 	unsigned int		boot_ro_lock;		/* ro lock support */
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index b01e77d..45d53ef 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -140,7 +140,7 @@ struct mmc_request {
 struct mmc_card;
 struct mmc_async_req;
 
-extern int mmc_stop_bkops(struct mmc_card *);
+extern int mmc_stop_bkops(struct mmc_card *, bool);
 extern int mmc_read_bkops_status(struct mmc_card *);
 extern struct mmc_async_req *mmc_start_req(struct mmc_host *,
 					   struct mmc_async_req *, int *);
@@ -150,7 +150,7 @@ extern int mmc_wait_for_cmd(struct mmc_host *, struct mmc_command *, int);
 extern int mmc_app_cmd(struct mmc_host *, struct mmc_card *);
 extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
 	struct mmc_command *, int);
-extern void mmc_start_bkops(struct mmc_card *card, bool from_exception);
+extern void mmc_start_bkops(struct mmc_card *, bool, bool);
 extern int mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int);
 extern int mmc_send_tuning(struct mmc_host *host, u32 opcode, int *cmd_error);
 extern int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd);
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index c376209..a1cced9 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -436,6 +436,7 @@ struct _mmc_csd {
  * BKOPS modes
  */
 #define EXT_CSD_MANUAL_BKOPS_MASK	0x01
+#define EXT_CSD_AUTO_BKOPS_MASK		0x02
 
 /*
  * MMC_SWITCH access modes
-- 
2.3.7

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