mmc: core: add partial initialization support

This change adds the ability to partially initialize
the MMC card by using card Sleep/Awake sequence (CMD5).
Card will be sent to Sleep state during runtime/system suspend
and will be woken up during runtime/system resume.
By using this sequence the card doesn't need full initialization
which gives time reduction in system/runtime resume path.

Change-Id: Id8dadf03ef4226f7c4675fadbacac7bb15c0289e
Signed-off-by: Talel Shenhar <tatias@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
[subhashj@codeaurora.org: fixed merge conflicts & compilation errors]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>

drivers/mmc/core/mmc.c

@@ -1542,7 +1542,7 @@ static int mmc_select_cmdq(struct mmc_card *card)
 	}
 
 	mmc_host_clk_release(card->host);
-	pr_info("%s: CMDQ enabled on card\n", mmc_hostname(host));
+	pr_info_once("%s: CMDQ enabled on card\n", mmc_hostname(host));
 out:
 	return ret;
 }
@@ -2181,12 +2181,13 @@ err:
 	return err;
 }
 
-static int mmc_can_sleep(struct mmc_card *card)
+static int mmc_can_sleepawake(struct mmc_host *host)
 {
-	return (card && card->ext_csd.rev >= 3);
+	return host && (host->caps2 & MMC_CAP2_SLEEP_AWAKE) && host->card &&
+		(host->card->ext_csd.rev >= 3);
 }
 
-static int mmc_sleep(struct mmc_host *host)
+static int mmc_sleepawake(struct mmc_host *host, bool sleep)
 {
 	struct mmc_command cmd = {0};
 	struct mmc_card *card = host->card;
@@ -2196,13 +2197,16 @@ static int mmc_sleep(struct mmc_host *host)
 	/* Re-tuning can't be done once the card is deselected */
 	mmc_retune_hold(host);
 
-	err = mmc_deselect_cards(host);
-	if (err)
-		goto out_release;
+	if (sleep) {
+		err = mmc_deselect_cards(host);
+		if (err)
+			goto out_release;
+	}
 
 	cmd.opcode = MMC_SLEEP_AWAKE;
 	cmd.arg = card->rca << 16;
-	cmd.arg |= 1 << 15;
+	if (sleep)
+		cmd.arg |= 1 << 15;
 
 	/*
 	 * If the max_busy_timeout of the host is specified, validate it against
@@ -2230,6 +2234,9 @@ static int mmc_sleep(struct mmc_host *host)
 	if (!cmd.busy_timeout || !(host->caps & MMC_CAP_WAIT_WHILE_BUSY))
 		mmc_delay(timeout_ms);
 
+	if (!sleep)
+		err = mmc_select_card(card);
+
 out_release:
 	mmc_retune_release(host);
 	return err;
@@ -2340,6 +2347,69 @@ static void mmc_detect(struct mmc_host *host)
 	}
 }
 
+static int mmc_cache_card_ext_csd(struct mmc_host *host)
+{
+	int err;
+	u8 *ext_csd;
+	struct mmc_card *card = host->card;
+
+	err = mmc_get_ext_csd(card, &ext_csd);
+	if (err || !ext_csd) {
+		pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
+			mmc_hostname(host), __func__, err);
+		return err;
+	}
+
+	/* only cache read/write fields that the sw changes */
+	card->ext_csd.raw_ext_csd_cmdq = ext_csd[EXT_CSD_CMDQ];
+	card->ext_csd.raw_ext_csd_cache_ctrl = ext_csd[EXT_CSD_CACHE_CTRL];
+	card->ext_csd.raw_ext_csd_bus_width = ext_csd[EXT_CSD_BUS_WIDTH];
+	card->ext_csd.raw_ext_csd_hs_timing = ext_csd[EXT_CSD_HS_TIMING];
+
+	kfree(ext_csd);
+
+	return 0;
+}
+
+static int mmc_test_awake_ext_csd(struct mmc_host *host)
+{
+	int err;
+	u8 *ext_csd;
+	struct mmc_card *card = host->card;
+
+	err = mmc_get_ext_csd(card, &ext_csd);
+	if (err) {
+		pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
+			mmc_hostname(host), __func__, err);
+		return err;
+	}
+
+	/* only compare read/write fields that the sw changes */
+	pr_debug("%s: %s: type(cached:current) cmdq(%d:%d) cache_ctrl(%d:%d) bus_width (%d:%d) timing(%d:%d)\n",
+		mmc_hostname(host), __func__,
+		card->ext_csd.raw_ext_csd_cmdq,
+		ext_csd[EXT_CSD_CMDQ],
+		card->ext_csd.raw_ext_csd_cache_ctrl,
+		ext_csd[EXT_CSD_CACHE_CTRL],
+		card->ext_csd.raw_ext_csd_bus_width,
+		ext_csd[EXT_CSD_BUS_WIDTH],
+		card->ext_csd.raw_ext_csd_hs_timing,
+		ext_csd[EXT_CSD_HS_TIMING]);
+
+	err = !((card->ext_csd.raw_ext_csd_cmdq ==
+			ext_csd[EXT_CSD_CMDQ]) &&
+		(card->ext_csd.raw_ext_csd_cache_ctrl ==
+			ext_csd[EXT_CSD_CACHE_CTRL]) &&
+		(card->ext_csd.raw_ext_csd_bus_width ==
+			ext_csd[EXT_CSD_BUS_WIDTH]) &&
+		(card->ext_csd.raw_ext_csd_hs_timing ==
+			ext_csd[EXT_CSD_HS_TIMING]));
+
+	kfree(ext_csd);
+
+	return err;
+}
+
 static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 {
 	int err = 0;
@@ -2391,10 +2461,13 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 	if (err)
 		goto out;
 
-	if (mmc_can_sleep(host->card))
-		err = mmc_sleep(host);
-	else if (!mmc_host_is_spi(host))
+	if (mmc_can_sleepawake(host)) {
+		memcpy(&host->cached_ios, &host->ios, sizeof(host->cached_ios));
+		mmc_cache_card_ext_csd(host);
+		err = mmc_sleepawake(host, true);
+	} else if (!mmc_host_is_spi(host)) {
 		err = mmc_deselect_cards(host);
+	}
 
 	if (!err) {
 		mmc_power_off(host);
@@ -2409,6 +2482,71 @@ out:
 	return err;
 }
 
+static int mmc_partial_init(struct mmc_host *host)
+{
+	int err = 0;
+	struct mmc_card *card = host->card;
+
+	pr_debug("%s: %s: starting partial init\n",
+		mmc_hostname(host), __func__);
+
+	mmc_set_bus_width(host, host->cached_ios.bus_width);
+	mmc_set_timing(host, host->cached_ios.timing);
+	mmc_set_clock(host, host->cached_ios.clock);
+	mmc_set_bus_mode(host, host->cached_ios.bus_mode);
+
+	mmc_host_clk_hold(host);
+
+	if (mmc_card_hs200(card) || mmc_card_hs400(card)) {
+		if (card->ext_csd.strobe_support && host->ops->enhanced_strobe)
+			err = host->ops->enhanced_strobe(host);
+		else
+			err = host->ops->execute_tuning(host,
+				MMC_SEND_TUNING_BLOCK_HS200);
+		if (err)
+			pr_warn("%s: %s: tuning execution failed (%d)\n",
+				mmc_hostname(host), __func__, err);
+	}
+
+	/*
+	 * The ext_csd is read to make sure the card did not went through
+	 * Power-failure during sleep period.
+	 * A subset of the W/E_P, W/C_P register will be tested. In case
+	 * these registers values are different from the values that were
+	 * cached during suspend, we will conclude that a Power-failure occurred
+	 * and will do full initialization sequence.
+	 * In addition, full init sequence also transfer ext_csd before moving
+	 * to CMDQ mode which has a side affect of configuring SDHCI registers
+	 * which needed to be done before moving to CMDQ mode. The same
+	 * registers need to be configured for partial init.
+	 */
+	err = mmc_test_awake_ext_csd(host);
+	if (err) {
+		pr_debug("%s: %s: fail on ext_csd read (%d)\n",
+			mmc_hostname(host), __func__, err);
+		goto out;
+	}
+	pr_debug("%s: %s: reading and comparing ext_csd successful\n",
+		mmc_hostname(host), __func__);
+
+	if (card->ext_csd.cmdq_support && (card->host->caps2 &
+					   MMC_CAP2_CMD_QUEUE)) {
+		err = mmc_select_cmdq(card);
+		if (err) {
+			pr_warn("%s: %s: enabling CMDQ mode failed (%d)\n",
+					mmc_hostname(card->host),
+					__func__, err);
+		}
+	}
+out:
+	mmc_host_clk_release(host);
+
+	pr_debug("%s: %s: done partial init (%d)\n",
+		mmc_hostname(host), __func__, err);
+
+	return err;
+}
+
 /*
  * Suspend callback
  */
@@ -2434,7 +2572,7 @@ static int mmc_suspend(struct mmc_host *host)
  */
 static int _mmc_resume(struct mmc_host *host)
 {
-	int err = 0;
+	int err = -ENOSYS;
 	int retries;
 
 	BUG_ON(!host);
@@ -2450,7 +2588,18 @@ static int _mmc_resume(struct mmc_host *host)
 	mmc_power_up(host, host->card->ocr);
 	retries = 3;
 	while (retries) {
-		err = mmc_init_card(host, host->card->ocr, host->card);
+		if (mmc_can_sleepawake(host)) {
+			err = mmc_sleepawake(host, false);
+			if (!err)
+				err = mmc_partial_init(host);
+			if (err)
+				pr_err("%s: %s: awake failed (%d), fallback to full init\n",
+					mmc_hostname(host), __func__, err);
+		}
+
+		if (err)
+			err = mmc_init_card(host, host->card->ocr, host->card);
+
 		if (err) {
 			pr_err("%s: MMC card re-init failed rc = %d (retries = %d)\n",
 			       mmc_hostname(host), err, retries);

include/linux/mmc/card.h

@@ -93,6 +93,8 @@ struct mmc_ext_csd {
 	unsigned int            data_tag_unit_size;     /* DATA TAG UNIT size */
 	unsigned int		boot_ro_lock;		/* ro lock support */
 	bool			boot_ro_lockable;
+	u8			raw_ext_csd_cmdq;	/* 15 */
+	u8			raw_ext_csd_cache_ctrl;	/* 33 */
 	bool			ffu_capable;	/* Firmware upgrade support */
 #define MMC_FIRMWARE_LEN 8
 	u8			fwrev[MMC_FIRMWARE_LEN];  /* FW version */
@@ -100,8 +102,10 @@ struct mmc_ext_csd {
 	u8			raw_partition_support;	/* 160 */
 	u8			raw_rpmb_size_mult;	/* 168 */
 	u8			raw_erased_mem_count;	/* 181 */
+	u8			raw_ext_csd_bus_width;	/* 183 */
 	u8			strobe_support;		/* 184 */
 #define MMC_STROBE_SUPPORT	(1 << 0)
+	u8			raw_ext_csd_hs_timing;	/* 185 */
 	u8			raw_ext_csd_structure;	/* 194 */
 	u8			raw_card_type;		/* 196 */
 	u8			raw_driver_strength;	/* 197 */

include/linux/mmc/host.h

@@ -441,6 +441,8 @@ struct mmc_host {
 #define MMC_CAP2_NONHOTPLUG	(1 << 25)	/*Don't support hotplug*/
 #define MMC_CAP2_CMD_QUEUE	(1 << 26)	/* support eMMC command queue */
 #define MMC_CAP2_SANITIZE       (1 << 27)               /* Support Sanitize */
+#define MMC_CAP2_SLEEP_AWAKE	(1 << 28)	/* Use Sleep/Awake (CMD5) */
+
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 
 #ifdef CONFIG_MMC_CLKGATE
@@ -468,6 +470,7 @@ struct mmc_host {
 	spinlock_t		lock;		/* lock for claim and bus ops */
 
 	struct mmc_ios		ios;		/* current io bus settings */
+	struct mmc_ios		cached_ios;
 
 	/* group bitfields together to minimize padding */
 	unsigned int		use_spi_crc:1;