tifm_sd: replace command completion state machine with full checking

State machine used to to track mmc command state was found to be fragile
and unreliable, making many cards unusable. The safer solution is to perform
all needed checks at every card event.
Signed-off-by: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/tifm_sd.c

@@ -70,19 +70,14 @@ module_param(fixed_timeout, bool, 0644);
 #define TIFM_MMCSD_CMD_AC     0x2000
 #define TIFM_MMCSD_CMD_ADTC   0x3000
 
-typedef enum {
-	IDLE = 0,
-	CMD,    /* main command ended                   */
-	BRS,    /* block transfer finished              */
-	SCMD,   /* stop command ended                   */
-	CARD,   /* card left busy state                 */
-	FIFO,   /* FIFO operation completed (uncertain) */
-	READY
-} card_state_t;
-
 enum {
-	FIFO_RDY   = 0x0001,     /* hardware dependent value */
-	CARD_BUSY  = 0x0010
+	CMD_READY    = 0x0001,
+	FIFO_READY   = 0x0002,
+	BRS_READY    = 0x0004,
+	SCMD_ACTIVE  = 0x0008,
+	SCMD_READY   = 0x0010,
+	CARD_BUSY    = 0x0020,
+	DATA_CARRY   = 0x0040
 };
 
 struct tifm_sd {
@@ -92,7 +87,7 @@ struct tifm_sd {
 			    open_drain:1,
 			    no_dma:1;
 	unsigned short      cmd_flags;
-	card_state_t        state;
+
 	unsigned int        clk_freq;
 	unsigned int        clk_div;
 	unsigned long       timeout_jiffies;
@@ -234,87 +229,76 @@ static void tifm_sd_fetch_resp(struct mmc_command *cmd, struct tifm_dev *sock)
 		       | readl(sock->addr + SOCK_MMCSD_RESPONSE + 0x00);
 }
 
-static void tifm_sd_process_cmd(struct tifm_dev *sock, struct tifm_sd *host,
-				       unsigned int host_status)
+static void tifm_sd_check_status(struct tifm_sd *host)
 {
+	struct tifm_dev *sock = host->dev;
 	struct mmc_command *cmd = host->req->cmd;
 
-change_state:
-	switch (host->state) {
-	case IDLE:
+	if (cmd->error != MMC_ERR_NONE)
+		goto finish_request;
+
+	if (!(host->cmd_flags & CMD_READY))
 		return;
-	case CMD:
-		if (host_status & (TIFM_MMCSD_EOC | TIFM_MMCSD_CERR)) {
-			tifm_sd_fetch_resp(cmd, sock);
-			if (cmd->data) {
-				host->state = BRS;
-			} else {
-				host->state = READY;
-			}
-			goto change_state;
-		}
-		break;
-	case BRS:
-		if (tifm_sd_transfer_data(sock, host, host_status)) {
-			if (cmd->data->flags & MMC_DATA_WRITE) {
-				host->state = CARD;
-			} else {
-				if (host->no_dma) {
-					if (host->req->stop) {
-						tifm_sd_exec(host, host->req->stop);
-						host->state = SCMD;
-					} else {
-						host->state = READY;
-					}
-				} else {
-					host->state = FIFO;
-				}
-			}
-			goto change_state;
-		}
-		break;
-	case SCMD:
-		if (host_status & TIFM_MMCSD_EOC) {
-			tifm_sd_fetch_resp(host->req->stop, sock);
-			host->state = READY;
-			goto change_state;
+
+	if (cmd->data) {
+		if (cmd->data->error != MMC_ERR_NONE) {
+			if ((host->cmd_flags & SCMD_ACTIVE)
+			    && !(host->cmd_flags & SCMD_READY))
+				return;
+
+			goto finish_request;
 		}
-		break;
-	case CARD:
-		dev_dbg(&sock->dev, "waiting for CARD, have %zd blocks\n",
-			host->written_blocks);
-		if (!(host->cmd_flags & CARD_BUSY)
-		    && (host->written_blocks == cmd->data->blocks)) {
-			if (host->no_dma) {
-				if (host->req->stop) {
+
+		if (!(host->cmd_flags & BRS_READY))
+			return;
+
+		if (!(host->no_dma || (host->cmd_flags & FIFO_READY)))
+			return;
+
+		if (cmd->data->flags & MMC_DATA_WRITE) {
+			if (host->req->stop) {
+				if (!(host->cmd_flags & SCMD_ACTIVE)) {
+					host->cmd_flags |= SCMD_ACTIVE;
+					writel(TIFM_MMCSD_EOFB
+					       | readl(sock->addr
+						       + SOCK_MMCSD_INT_ENABLE),
+					       sock->addr
+					       + SOCK_MMCSD_INT_ENABLE);
 					tifm_sd_exec(host, host->req->stop);
-					host->state = SCMD;
+					return;
 				} else {
-					host->state = READY;
+					if (!(host->cmd_flags & SCMD_READY)
+					    || (host->cmd_flags & CARD_BUSY))
+						return;
+					writel((~TIFM_MMCSD_EOFB)
+					       & readl(sock->addr
+						       + SOCK_MMCSD_INT_ENABLE),
+					       sock->addr
+					       + SOCK_MMCSD_INT_ENABLE);
 				}
 			} else {
-				host->state = FIFO;
+				if (host->cmd_flags & CARD_BUSY)
+					return;
+				writel((~TIFM_MMCSD_EOFB)
+				       & readl(sock->addr
+					       + SOCK_MMCSD_INT_ENABLE),
+				       sock->addr + SOCK_MMCSD_INT_ENABLE);
 			}
-			goto change_state;
-		}
-		break;
-	case FIFO:
-		if (host->cmd_flags & FIFO_RDY) {
-			host->cmd_flags &= ~FIFO_RDY;
+		} else {
 			if (host->req->stop) {
-				tifm_sd_exec(host, host->req->stop);
-				host->state = SCMD;
-			} else {
-				host->state = READY;
+				if (!(host->cmd_flags & SCMD_ACTIVE)) {
+					host->cmd_flags |= SCMD_ACTIVE;
+					tifm_sd_exec(host, host->req->stop);
+					return;
+				} else {
+					if (!(host->cmd_flags & SCMD_READY))
+						return;
+				}
 			}
-			goto change_state;
 		}
-		break;
-	case READY:
-		tasklet_schedule(&host->finish_tasklet);
-		return;
 	}
-
+finish_request:
+	tasklet_schedule(&host->finish_tasklet);
 }
 
 /* Called from interrupt handler */
@@ -322,21 +306,25 @@ static void tifm_sd_data_event(struct tifm_dev *sock)
 {
 	struct tifm_sd *host;
 	unsigned int fifo_status = 0;
+	struct mmc_data *r_data = NULL;
 
 	spin_lock(&sock->lock);
 	host = mmc_priv((struct mmc_host*)tifm_get_drvdata(sock));
-
 	fifo_status = readl(sock->addr + SOCK_DMA_FIFO_STATUS);
-	writel(fifo_status, sock->addr + SOCK_DMA_FIFO_STATUS);
+	dev_dbg(&sock->dev, "data event: fifo_status %x, flags %x\n",
+		fifo_status, host->cmd_flags);
 
-	host->cmd_flags |= fifo_status & FIFO_RDY;
+	if (host->req) {
+		r_data = host->req->cmd->data;
 
-	if (host->req)
-		tifm_sd_process_cmd(sock, host, 0);
+		if (r_data && (fifo_status & TIFM_FIFO_READY)) {
+			host->cmd_flags |= FIFO_READY;
+			tifm_sd_check_status(host);
+		}
+	}
 
-	dev_dbg(&sock->dev, "fifo_status %x\n", fifo_status);
+	writel(fifo_status, sock->addr + SOCK_DMA_FIFO_STATUS);
 	spin_unlock(&sock->lock);
-
 }
 
 /* Called from interrupt handler */
@@ -344,60 +332,88 @@ static void tifm_sd_card_event(struct tifm_dev *sock)
 {
 	struct tifm_sd *host;
 	unsigned int host_status = 0;
-	int error_code = 0;
+	int cmd_error = MMC_ERR_NONE;
+	struct mmc_command *cmd = NULL;
+	unsigned long flags;
 
 	spin_lock(&sock->lock);
 	host = mmc_priv((struct mmc_host*)tifm_get_drvdata(sock));
+	host_status = readl(sock->addr + SOCK_MMCSD_STATUS);
+	dev_dbg(&sock->dev, "host event: host_status %x, flags %x\n",
+		host_status, host->cmd_flags);
 
-
-		host_status = readl(sock->addr + SOCK_MMCSD_STATUS);
-		writel(host_status, sock->addr + SOCK_MMCSD_STATUS);
-
-		if (!host->req)
-			goto done;
+	if (host->req) {
+		cmd = host->req->cmd;
 
 		if (host_status & TIFM_MMCSD_ERRMASK) {
-			if (host_status & (TIFM_MMCSD_CTO | TIFM_MMCSD_DTO))
-				error_code = MMC_ERR_TIMEOUT;
-			else if (host_status
-				 & (TIFM_MMCSD_CCRC | TIFM_MMCSD_DCRC))
-				error_code = MMC_ERR_BADCRC;
+			writel(host_status & TIFM_MMCSD_ERRMASK,
+			       sock->addr + SOCK_MMCSD_STATUS);
+			if (host_status & TIFM_MMCSD_CTO)
+				cmd_error = MMC_ERR_TIMEOUT;
+			else if (host_status & TIFM_MMCSD_CCRC)
+				cmd_error = MMC_ERR_BADCRC;
+
+			if (cmd->data) {
+				if (host_status & TIFM_MMCSD_DTO)
+					cmd->data->error = MMC_ERR_TIMEOUT;
+				else if (host_status & TIFM_MMCSD_DCRC)
+					cmd->data->error = MMC_ERR_BADCRC;
+			}
 
 			writel(TIFM_FIFO_INT_SETALL,
 			       sock->addr + SOCK_DMA_FIFO_INT_ENABLE_CLEAR);
 			writel(TIFM_DMA_RESET, sock->addr + SOCK_DMA_CONTROL);
 
 			if (host->req->stop) {
-				if (host->state == SCMD) {
-					host->req->stop->error = error_code;
-				} else if (host->state == BRS
-					   || host->state == CARD
-					   || host->state == FIFO) {
-					host->req->cmd->error = error_code;
+				if (host->cmd_flags & SCMD_ACTIVE) {
+					host->req->stop->error = cmd_error;
+					host->cmd_flags |= SCMD_READY;
+				} else {
+					cmd->error = cmd_error;
+					host->cmd_flags |= SCMD_ACTIVE;
 					tifm_sd_exec(host, host->req->stop);
-					host->state = SCMD;
 					goto done;
-				} else {
-					host->req->cmd->error = error_code;
 				}
-			} else {
-				host->req->cmd->error = error_code;
+			} else
+				cmd->error = cmd_error;
+		} else {
+			if (host_status & (TIFM_MMCSD_EOC | TIFM_MMCSD_CERR)) {
+				if (!(host->cmd_flags & CMD_READY)) {
+					host->cmd_flags |= CMD_READY;
+					tifm_sd_fetch_resp(cmd, sock);
+				} else if (host->cmd_flags & SCMD_ACTIVE) {
+					host->cmd_flags |= SCMD_READY;
+					tifm_sd_fetch_resp(host->req->stop,
+							   sock);
+				}
 			}
-			host->state = READY;
+			if (host_status & TIFM_MMCSD_BRS)
+				host->cmd_flags |= BRS_READY;
 		}
 
-		if (host_status & TIFM_MMCSD_CB)
-			host->cmd_flags |= CARD_BUSY;
-		if ((host_status & TIFM_MMCSD_EOFB)
-		    && (host->cmd_flags & CARD_BUSY)) {
-			host->written_blocks++;
-			host->cmd_flags &= ~CARD_BUSY;
+		if (host->no_dma && cmd->data) {
+			if (host_status & TIFM_MMCSD_AE)
+				writel(host_status & TIFM_MMCSD_AE,
+				       sock->addr + SOCK_MMCSD_STATUS);
+
+			if (host_status & (TIFM_MMCSD_AE | TIFM_MMCSD_AF
+					   | TIFM_MMCSD_BRS)) {
+				local_irq_save(flags);
+				tifm_sd_transfer_data(sock, host, host_status);
+				local_irq_restore(flags);
+				host_status &= ~TIFM_MMCSD_AE;
+			}
 		}
 
-	if (host->req)
-		tifm_sd_process_cmd(sock, host, host_status);
+		if (host_status & TIFM_MMCSD_EOFB)
+			host->cmd_flags &= ~CARD_BUSY;
+		else if (host_status & TIFM_MMCSD_CB)
+			host->cmd_flags |= CARD_BUSY;
+
+		tifm_sd_check_status(host);
+	}
 done:
-	dev_dbg(&sock->dev, "host_status %x\n", host_status);
+	writel(host_status, sock->addr + SOCK_MMCSD_STATUS);
 	spin_unlock(&sock->lock);
 }
 
@@ -522,7 +538,7 @@ static void tifm_sd_request(struct mmc_host *mmc, struct mmc_request *mrq)
 
 	host->req = mrq;
 	mod_timer(&host->timer, jiffies + host->timeout_jiffies);
-	host->state = CMD;
+	host->cmd_flags = 0;
 	writel(TIFM_CTRL_LED | readl(sock->addr + SOCK_CONTROL),
 	       sock->addr + SOCK_CONTROL);
 	tifm_sd_exec(host, mrq->cmd);
@@ -553,7 +569,6 @@ static void tifm_sd_end_cmd(unsigned long data)
 	del_timer(&host->timer);
 	mrq = host->req;
 	host->req = NULL;
-	host->state = IDLE;
 
 	if (!mrq) {
 		printk(KERN_ERR DRIVER_NAME ": no request to complete?\n");

include/linux/tifm.h

@@ -67,6 +67,7 @@ enum {
 #define TIFM_SOCK_STATE_POWERED   0x00000080
 
 #define TIFM_FIFO_ENABLE          0x00000001 /* Meaning of this constant is unverified */
+#define TIFM_FIFO_READY           0x00000001 /* Meaning of this constant is unverified */
 #define TIFM_FIFO_INT_SETALL      0x0000ffff
 #define TIFM_FIFO_INTMASK         0x00000005 /* Meaning of this constant is unverified */