mmc: core: implement enhanced strobe support

Controllers use data strobe line to latch data from devices
under hs400 mode, but not for cmd line. So since emmc 5.1, JEDEC
introduces enhanced strobe mode for latching cmd response from
emmc devices to host controllers. This new feature is optional,
so it depends both on device's cap and host's cap to decide
whether to use it or not.

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

Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 82 insertions, 2 deletions

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 5d438ad3ee32..97a664f758b0 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -235,6 +235,11 @@ static void mmc_select_card_type(struct mmc_card *card)
 		avail_type |= EXT_CSD_CARD_TYPE_HS400_1_2V;
 	}
 
+	if ((caps2 & MMC_CAP2_HS400_ES) &&
+	    card->ext_csd.strobe_support &&
+	    (avail_type & EXT_CSD_CARD_TYPE_HS400))
+		avail_type |= EXT_CSD_CARD_TYPE_HS400ES;
+
 	card->ext_csd.hs_max_dtr = hs_max_dtr;
 	card->ext_csd.hs200_max_dtr = hs200_max_dtr;
 	card->mmc_avail_type = avail_type;
@@ -386,6 +391,7 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 			mmc_card_set_blockaddr(card);
 	}
 
+	card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT];
 	card->ext_csd.raw_card_type = ext_csd[EXT_CSD_CARD_TYPE];
 	mmc_select_card_type(card);
 
@@ -1223,6 +1229,78 @@ out_err:
 	return err;
 }
 
+static int mmc_select_hs400es(struct mmc_card *card)
+{
+	struct mmc_host *host = card->host;
+	int err = 0;
+	u8 val;
+
+	if (!(host->caps & MMC_CAP_8_BIT_DATA)) {
+		err = -ENOTSUPP;
+		goto out_err;
+	}
+
+	err = mmc_select_bus_width(card);
+	if (err < 0)
+		goto out_err;
+
+	/* Switch card to HS mode */
+	err = mmc_select_hs(card);
+	if (err) {
+		pr_err("%s: switch to high-speed failed, err:%d\n",
+			mmc_hostname(host), err);
+		goto out_err;
+	}
+
+	err = mmc_switch_status(card);
+	if (err)
+		goto out_err;
+
+	/* Switch card to DDR with strobe bit */
+	val = EXT_CSD_DDR_BUS_WIDTH_8 | EXT_CSD_BUS_WIDTH_STROBE;
+	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			 EXT_CSD_BUS_WIDTH,
+			 val,
+			 card->ext_csd.generic_cmd6_time);
+	if (err) {
+		pr_err("%s: switch to bus width for hs400es failed, err:%d\n",
+			mmc_hostname(host), err);
+		goto out_err;
+	}
+
+	/* Switch card to HS400 */
+	val = EXT_CSD_TIMING_HS400 |
+	      card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
+	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			   EXT_CSD_HS_TIMING, val,
+			   card->ext_csd.generic_cmd6_time,
+			   true, false, true);
+	if (err) {
+		pr_err("%s: switch to hs400es failed, err:%d\n",
+			mmc_hostname(host), err);
+		goto out_err;
+	}
+
+	/* Set host controller to HS400 timing and frequency */
+	mmc_set_timing(host, MMC_TIMING_MMC_HS400);
+
+	/* Controller enable enhanced strobe function */
+	host->ios.enhanced_strobe = true;
+	if (host->ops->hs400_enhanced_strobe)
+		host->ops->hs400_enhanced_strobe(host, &host->ios);
+
+	err = mmc_switch_status(card);
+	if (err)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
+	       __func__, err);
+	return err;
+}
+
 static void mmc_select_driver_type(struct mmc_card *card)
 {
 	int card_drv_type, drive_strength, drv_type;
@@ -1310,7 +1388,7 @@ err:
 }
 
 /*
- * Activate High Speed or HS200 mode if supported.
+ * Activate High Speed, HS200 or HS400ES mode if supported.
  */
 static int mmc_select_timing(struct mmc_card *card)
 {
@@ -1319,7 +1397,9 @@ static int mmc_select_timing(struct mmc_card *card)
 	if (!mmc_can_ext_csd(card))
 		goto bus_speed;
 
-	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
+		err = mmc_select_hs400es(card);
+	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
 		err = mmc_select_hs200(card);
 	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
 		err = mmc_select_hs(card);