mmc: mmci: Use a switch statement machine

As is custom, use a big switch statement to transition
between the edges of the state machine inside
the ux500 ->busy_complete callback.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v7-8-69a7164f2a61@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: Linus Walleij

drivers/mmc/host/mmci.c

@@ -686,6 +686,12 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 		goto out_ret_state;
 	}
 
+	/*
+	 * The state transitions are encoded in a state machine crossing
+	 * the edges in this switch statement.
+	 */
+	switch (host->busy_state) {
+
 	/*
 	 * Before unmasking for the busy end IRQ, confirm that the
 	 * command was sent successfully. To keep track of having a
@@ -696,7 +702,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 	 * it starts signaling busy on DAT0, hence re-read the
 	 * MMCISTATUS register here, to allow the busy bit to be set.
 	 */
-	if (host->busy_state == MMCI_BUSY_DONE) {
+	case MMCI_BUSY_DONE:
 		/*
 		 * Save the first status register read to be sure to catch
 		 * all bits that may be lost will retrying. If the command
@@ -722,8 +728,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 		writel(readl(base + MMCIMASK0) &
 		       ~host->variant->busy_detect_mask, base + MMCIMASK0);
 		host->busy_state = MMCI_BUSY_DONE;
-		goto out_ret_state;
-	}
+		break;
 
 	/*
 	 * If there is a command in-progress that has been successfully
@@ -736,12 +741,11 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 	 * both the start and the end interrupts needs to be cleared,
 	 * one after the other. So, clear the busy start IRQ here.
 	 */
-	if (host->busy_state == MMCI_BUSY_WAITING_FOR_START_IRQ) {
+	case MMCI_BUSY_WAITING_FOR_START_IRQ:
 		if (status & host->variant->busy_detect_flag) {
 			host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND);
 			writel(host->variant->busy_detect_mask, base + MMCICLEAR);
 			host->busy_state = MMCI_BUSY_WAITING_FOR_END_IRQ;
-			goto out_ret_state;
 		} else {
 			dev_dbg(mmc_dev(host->mmc),
 				"lost busy status when waiting for busy start IRQ\n");
@@ -750,23 +754,24 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 			       ~host->variant->busy_detect_mask, base + MMCIMASK0);
 			host->busy_state = MMCI_BUSY_DONE;
 			host->busy_status = 0;
-			goto out_ret_state;
 		}
-	}
+		break;
 
-	if (host->busy_state == MMCI_BUSY_WAITING_FOR_END_IRQ) {
+	case MMCI_BUSY_WAITING_FOR_END_IRQ:
 		if (!(status & host->variant->busy_detect_flag)) {
 			host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND);
 			host->busy_state = MMCI_BUSY_DONE;
-			goto out_ret_state;
 		} else {
 			dev_dbg(mmc_dev(host->mmc),
 				"busy status still asserted when handling busy end IRQ - will keep waiting\n");
-			goto out_ret_state;
 		}
-	}
+		break;
 
-	return true;
+	default:
+		dev_dbg(mmc_dev(host->mmc), "fell through on state %d\n",
+			host->busy_state);
+		break;
+	}
 
 out_ret_state:
 	return (host->busy_state == MMCI_BUSY_DONE);