drivers: mmc: add SD support for Command Queueing

Application class A2 cards require CQ to be enabled to realise their
stated performance figures. Add support to enable/disable card CQ via
the Performance Enhancement extension register, and cater for the slight
differences in command set versus eMMC.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>

drivers/mmc/core/block.c

@@ -896,7 +896,10 @@ static int mmc_blk_part_switch_pre(struct mmc_card *card,
 
 	if ((part_type & mask) == rpmb) {
 		if (card->ext_csd.cmdq_en) {
-			ret = mmc_cmdq_disable(card);
+			if (mmc_card_sd(card))
+				ret = mmc_sd_cmdq_disable(card);
+			else
+				ret = mmc_cmdq_disable(card);
 			if (ret)
 				return ret;
 		}
@@ -915,8 +918,12 @@ static int mmc_blk_part_switch_post(struct mmc_card *card,
 
 	if ((part_type & mask) == rpmb) {
 		mmc_retune_unpause(card->host);
-		if (card->reenable_cmdq && !card->ext_csd.cmdq_en)
-			ret = mmc_cmdq_enable(card);
+		if (card->reenable_cmdq && !card->ext_csd.cmdq_en) {
+			if (mmc_card_sd(card))
+				ret = mmc_sd_cmdq_enable(card);
+			else
+				ret = mmc_cmdq_enable(card);
+		}
 	}
 
 	return ret;
@@ -1127,7 +1134,10 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 	switch (mq_rq->drv_op) {
 	case MMC_DRV_OP_IOCTL:
 		if (card->ext_csd.cmdq_en) {
-			ret = mmc_cmdq_disable(card);
+			if (mmc_card_sd(card))
+				ret = mmc_sd_cmdq_disable(card);
+			else
+				ret = mmc_cmdq_disable(card);
 			if (ret)
 				break;
 		}
@@ -1145,8 +1155,12 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 		/* Always switch back to main area after RPMB access */
 		if (rpmb_ioctl)
 			mmc_blk_part_switch(card, 0);
-		else if (card->reenable_cmdq && !card->ext_csd.cmdq_en)
-			mmc_cmdq_enable(card);
+		else if (card->reenable_cmdq && !card->ext_csd.cmdq_en) {
+			if (mmc_card_sd(card))
+				mmc_sd_cmdq_enable(card);
+			else
+				mmc_cmdq_enable(card);
+		}
 		break;
 	case MMC_DRV_OP_BOOT_WP:
 		ret = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BOOT_WP,

drivers/mmc/core/core.c

@@ -563,7 +563,11 @@ int mmc_cqe_recovery(struct mmc_host *host)
 	mmc_poll_for_busy(host->card, MMC_CQE_RECOVERY_TIMEOUT, true, MMC_BUSY_IO);
 
 	memset(&cmd, 0, sizeof(cmd));
-	cmd.opcode       = MMC_CMDQ_TASK_MGMT;
+	if (mmc_card_sd(host->card))
+		cmd.opcode = SD_CMDQ_TASK_MGMT;
+	else
+		cmd.opcode = MMC_CMDQ_TASK_MGMT;
+
 	cmd.arg          = 1; /* Discard entire queue */
 	cmd.flags        = MMC_RSP_R1B_NO_CRC | MMC_CMD_AC; /* Ignore CRC */
 	cmd.busy_timeout = MMC_CQE_RECOVERY_TIMEOUT;

drivers/mmc/core/sd.c

@@ -1034,8 +1034,8 @@ static bool mmc_sd_card_using_v18(struct mmc_card *card)
 	       (SD_MODE_UHS_SDR50 | SD_MODE_UHS_SDR104 | SD_MODE_UHS_DDR50);
 }
 
-static int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
-			    u8 reg_data)
+int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
+		     u8 reg_data)
 {
 	struct mmc_host *host = card->host;
 	struct mmc_request mrq = {};
@@ -1193,8 +1193,14 @@ static int sd_parse_ext_reg_perf(struct mmc_card *card, u8 fno, u8 page,
 		card->ext_perf.feature_support |= SD_EXT_PERF_CACHE;
 
 	/* Command queue support indicated via queue depth bits (0 to 4). */
-	if (reg_buf[6] & 0x1f)
+	if (reg_buf[6] & 0x1f) {
 		card->ext_perf.feature_support |= SD_EXT_PERF_CMD_QUEUE;
+		card->ext_csd.cmdq_depth = reg_buf[6] & 0x1f;
+		card->ext_csd.cmdq_support = true;
+		pr_debug("%s: Command Queue supported depth %u\n",
+			 mmc_hostname(card->host),
+			 card->ext_csd.cmdq_depth);
+	}
 
 	card->ext_perf.fno = fno;
 	card->ext_perf.page = page;
@@ -1584,13 +1590,41 @@ cont:
 			goto free_card;
 	}
 
+	/* Enable command queueing if supported */
+	if (card->ext_csd.cmdq_support && host->caps2 & MMC_CAP2_CQE) {
+		/*
+		 * Right now the MMC block layer uses DCMDs to issue
+		 * cache-flush commands specific to eMMC devices.
+		 * Turning off DCMD support avoids generating Illegal Command
+		 * errors on SD, and flushing is instead done synchronously
+		 * by mmc_blk_issue_flush().
+		 */
+		host->caps2 &= ~MMC_CAP2_CQE_DCMD;
+		err = mmc_sd_cmdq_enable(card);
+		if (err && err != -EBADMSG)
+			goto free_card;
+		if (err) {
+			pr_warn("%s: Enabling CMDQ failed\n",
+				mmc_hostname(card->host));
+			card->ext_csd.cmdq_support = false;
+			card->ext_csd.cmdq_depth = 0;
+		}
+	}
+	card->reenable_cmdq = card->ext_csd.cmdq_en;
+
 	if (!mmc_card_ult_capacity(card) && host->cqe_ops && !host->cqe_enabled) {
 		err = host->cqe_ops->cqe_enable(host, card);
 		if (!err) {
 			host->cqe_enabled = true;
-			host->hsq_enabled = true;
-			pr_info("%s: Host Software Queue enabled\n",
-				mmc_hostname(host));
+
+			if (card->ext_csd.cmdq_en) {
+				pr_info("%s: Command Queue Engine enabled\n",
+					mmc_hostname(host));
+			} else {
+				host->hsq_enabled = true;
+				pr_info("%s: Host Software Queue enabled\n",
+					mmc_hostname(host));
+			}
 		}
 	}
 

drivers/mmc/core/sd_ops.c

@@ -417,3 +417,40 @@ int mmc_app_sd_status(struct mmc_card *card, void *ssr)
 
 	return 0;
 }
+
+int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
+		     u8 reg_data);
+
+static int mmc_sd_cmdq_switch(struct mmc_card *card, bool enable)
+{
+	int err;
+	u8 reg = 0;
+	/*
+	 * SD offers two command queueing modes - sequential (in-order) and
+	 * voluntary (out-of-order). Apps Class A2 performance is only
+	 * guaranteed for voluntary CQ (bit 1 = 0), so use that in preference
+	 * to sequential.
+	 */
+	if (enable)
+		reg = BIT(0);
+
+	/* Performance enhancement register byte 262 controls command queueing */
+	err = sd_write_ext_reg(card, card->ext_perf.fno, card->ext_perf.page,
+			       card->ext_perf.offset + 262, reg);
+	if (!err)
+		card->ext_csd.cmdq_en = enable;
+
+	return err;
+}
+
+int mmc_sd_cmdq_enable(struct mmc_card *card)
+{
+	return mmc_sd_cmdq_switch(card, true);
+}
+EXPORT_SYMBOL_GPL(mmc_sd_cmdq_enable);
+
+int mmc_sd_cmdq_disable(struct mmc_card *card)
+{
+	return mmc_sd_cmdq_switch(card, false);
+}
+EXPORT_SYMBOL_GPL(mmc_sd_cmdq_disable);

drivers/mmc/core/sd_ops.h

@@ -24,6 +24,8 @@ int mmc_app_sd_status(struct mmc_card *card, void *ssr);
 int mmc_app_cmd(struct mmc_host *host, struct mmc_card *card);
 int mmc_send_ext_addr(struct mmc_host *host, u32 addr);
 void mmc_uhs2_prepare_cmd(struct mmc_host *host, struct mmc_request *mrq);
+int mmc_sd_cmdq_enable(struct mmc_card *card);
+int mmc_sd_cmdq_disable(struct mmc_card *card);
 
 #endif
 

include/linux/mmc/sd.h

@@ -32,6 +32,9 @@
 #define SD_APP_OP_COND           41   /* bcr  [31:0] OCR         R3  */
 #define SD_APP_SEND_SCR          51   /* adtc                    R1  */
 
+  /* class 1 */
+#define SD_CMDQ_TASK_MGMT        43   /* ac   See below          R1b */
+
   /* class 11 */
 #define SD_READ_EXTR_SINGLE      48   /* adtc [31:0]             R1  */
 #define SD_WRITE_EXTR_SINGLE     49   /* adtc [31:0]             R1  */
@@ -64,6 +67,15 @@
  *	[7:0] Check Pattern (0xAA)
  */
 
+/*
+ * SD_CMDQ_TASK_MGMT argument format:
+ *
+ * [31:21] Reserved (0)
+ * [20:16] Task ID
+ * [15:4] Reserved (0)
+ * [3:0] Operation - 0x1 = abort all tasks, 0x2 = abort Task ID
+ */
+
 /*
  * SCR field definitions
  */