mmc: core: Add Power Off Notify Feature eMMC 4.5

This patch adds support for the power off notify feature, available in
eMMC 4.5 devices. If the host has support for this feature, then the
mmc core will notify the device by setting the POWER_OFF_NOTIFICATION
byte in the extended csd register with a value of 1 (POWER_ON).

For suspend mode short timeout is used, whereas for the normal poweroff
long timeout is used.
Signed-off-by: Girish K S <girish.shivananjappa@linaro.org>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/core.c

@@ -1212,11 +1212,43 @@ static void mmc_power_up(struct mmc_host *host)
 
 void mmc_power_off(struct mmc_host *host)
 {
+	struct mmc_card *card;
+	unsigned int notify_type;
+	unsigned int timeout;
+	int err;
+
 	mmc_host_clk_hold(host);
 
+	card = host->card;
 	host->ios.clock = 0;
 	host->ios.vdd = 0;
 
+	if (card && mmc_card_mmc(card) &&
+	    (card->poweroff_notify_state == MMC_POWERED_ON)) {
+
+		if (host->power_notify_type == MMC_HOST_PW_NOTIFY_SHORT) {
+			notify_type = EXT_CSD_POWER_OFF_SHORT;
+			timeout = card->ext_csd.generic_cmd6_time;
+			card->poweroff_notify_state = MMC_POWEROFF_SHORT;
+		} else {
+			notify_type = EXT_CSD_POWER_OFF_LONG;
+			timeout = card->ext_csd.power_off_longtime;
+			card->poweroff_notify_state = MMC_POWEROFF_LONG;
+		}
+
+		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_POWER_OFF_NOTIFICATION,
+				 notify_type, timeout);
+
+		if (err && err != -EBADMSG)
+			pr_err("Device failed to respond within %d poweroff "
+			       "time. Forcefully powering down the device\n",
+			       timeout);
+
+		/* Set the card state to no notification after the poweroff */
+		card->poweroff_notify_state = MMC_NO_POWER_NOTIFICATION;
+	}
+
 	/*
 	 * Reset ocr mask to be the highest possible voltage supported for
 	 * this mmc host. This value will be used at next power up.
@@ -2208,6 +2240,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 
 		spin_lock_irqsave(&host->lock, flags);
 		host->rescan_disable = 1;
+		host->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
 		spin_unlock_irqrestore(&host->lock, flags);
 		cancel_delayed_work_sync(&host->detect);
 
@@ -2231,6 +2264,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 
 		spin_lock_irqsave(&host->lock, flags);
 		host->rescan_disable = 0;
+		host->power_notify_type = MMC_HOST_PW_NOTIFY_LONG;
 		spin_unlock_irqrestore(&host->lock, flags);
 		mmc_detect_change(host, 0);
 

drivers/mmc/core/mmc.c

@@ -458,10 +458,12 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
 	else
 		card->erased_byte = 0x0;
 
-	if (card->ext_csd.rev >= 6)
+	if (card->ext_csd.rev >= 6) {
 		card->ext_csd.generic_cmd6_time = 10 *
 			ext_csd[EXT_CSD_GENERIC_CMD6_TIME];
-	else
+		card->ext_csd.power_off_longtime = 10 *
+			ext_csd[EXT_CSD_POWER_OFF_LONG_TIME];
+	} else
 		card->ext_csd.generic_cmd6_time = 0;
 
 out:
@@ -845,6 +847,23 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 			goto free_card;
 	}
 
+	/*
+	 * If the host supports the power_off_notify capability then
+	 * set the notification byte in the ext_csd register of device
+	 */
+	if ((host->caps2 & MMC_CAP2_POWEROFF_NOTIFY) &&
+	    (card->poweroff_notify_state == MMC_NO_POWER_NOTIFICATION)) {
+		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_POWER_OFF_NOTIFICATION,
+				 EXT_CSD_POWER_ON,
+				 card->ext_csd.generic_cmd6_time);
+		if (err && err != -EBADMSG)
+			goto free_card;
+	}
+
+	if (!err)
+		card->poweroff_notify_state = MMC_POWERED_ON;
+
 	/*
 	 * Activate high speed (if supported)
 	 */

drivers/mmc/host/sdhci.c

@@ -2739,6 +2739,15 @@ int sdhci_add_host(struct sdhci_host *host)
 	if (caps[1] & SDHCI_DRIVER_TYPE_D)
 		mmc->caps |= MMC_CAP_DRIVER_TYPE_D;
 
+	/*
+	 * If Power Off Notify capability is enabled by the host,
+	 * set notify to short power off notify timeout value.
+	 */
+	if (mmc->caps2 & MMC_CAP2_POWEROFF_NOTIFY)
+		mmc->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
+	else
+		mmc->power_notify_type = MMC_HOST_PW_NOTIFY_NONE;
+
 	/* Initial value for re-tuning timer count */
 	host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
 			      SDHCI_RETUNING_TIMER_COUNT_SHIFT;

include/linux/mmc/card.h

@@ -55,6 +55,7 @@ struct mmc_ext_csd {
 	unsigned int		part_time;		/* Units: ms */
 	unsigned int		sa_timeout;		/* Units: 100ns */
 	unsigned int		generic_cmd6_time;	/* Units: 10ms */
+	unsigned int            power_off_longtime;     /* Units: ms */
 	unsigned int		hs_max_dtr;
 	unsigned int		sectors;
 	unsigned int		card_type;
@@ -209,6 +210,11 @@ struct mmc_card {
 #define MMC_QUIRK_BLK_NO_CMD23	(1<<7)		/* Avoid CMD23 for regular multiblock */
 #define MMC_QUIRK_BROKEN_BYTE_MODE_512 (1<<8)	/* Avoid sending 512 bytes in */
 						/* byte mode */
+	unsigned int    poweroff_notify_state;	/* eMMC4.5 notify feature */
+#define MMC_NO_POWER_NOTIFICATION	0
+#define MMC_POWERED_ON			1
+#define MMC_POWEROFF_SHORT		2
+#define MMC_POWEROFF_LONG		3
 
 	unsigned int		erase_size;	/* erase size in sectors */
  	unsigned int		erase_shift;	/* if erase unit is power 2 */

include/linux/mmc/host.h

@@ -239,8 +239,13 @@ struct mmc_host {
 	unsigned int		caps2;		/* More host capabilities */
 
 #define MMC_CAP2_BOOTPART_NOACC	(1 << 0)	/* Boot partition no access */
+#define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)	/* Notify poweroff supported */
 
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
+	unsigned int        power_notify_type;
+#define MMC_HOST_PW_NOTIFY_NONE		0
+#define MMC_HOST_PW_NOTIFY_SHORT	1
+#define MMC_HOST_PW_NOTIFY_LONG		2
 
 #ifdef CONFIG_MMC_CLKGATE
 	int			clk_requests;	/* internal reference counter */

include/linux/mmc/mmc.h

@@ -270,6 +270,7 @@ struct _mmc_csd {
  * EXT_CSD fields
  */
 
+#define EXT_CSD_POWER_OFF_NOTIFICATION	34	/* R/W */
 #define EXT_CSD_GP_SIZE_MULT		143	/* R/W */
 #define EXT_CSD_PARTITION_ATTRIBUTE	156	/* R/W */
 #define EXT_CSD_PARTITION_SUPPORT	160	/* RO */
@@ -346,6 +347,11 @@ struct _mmc_csd {
 #define EXT_CSD_RST_N_EN_MASK	0x3
 #define EXT_CSD_RST_N_ENABLED	1	/* RST_n is enabled on card */
 
+#define EXT_CSD_NO_POWER_NOTIFICATION	0
+#define EXT_CSD_POWER_ON		1
+#define EXT_CSD_POWER_OFF_SHORT		2
+#define EXT_CSD_POWER_OFF_LONG		3
+
 #define EXT_CSD_PWR_CL_8BIT_MASK	0xF0	/* 8 bit PWR CLS */
 #define EXT_CSD_PWR_CL_4BIT_MASK	0x0F	/* 8 bit PWR CLS */
 #define EXT_CSD_PWR_CL_8BIT_SHIFT	4