mmc: mmci: Add support for SW busy-end timeouts

The ux500 variant doesn't have a HW based timeout to use for busy-end IRQs.
To avoid hanging and waiting for the card to stop signaling busy, let's
schedule a delayed work, according to the corresponding cmd->busy_timeout
for the command. If the work gets to run, let's kick the IRQ handler to
complete the currently running request/command.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20230620091113.33393-1-ulf.hansson@linaro.org

Author: Ulf Hansson

drivers/mmc/host/mmci.c

@@ -37,6 +37,7 @@
 #include <linux/pinctrl/consumer.h>
 #include <linux/reset.h>
 #include <linux/gpio/consumer.h>
+#include <linux/workqueue.h>
 
 #include <asm/div64.h>
 #include <asm/io.h>
@@ -712,7 +713,8 @@ static void ux500_busy_clear_mask_done(struct mmci_host *host)
  *                     |                 |
  *                    IRQ1              IRQ2
  */
-static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
+static bool ux500_busy_complete(struct mmci_host *host, struct mmc_command *cmd,
+				u32 status, u32 err_msk)
 {
 	void __iomem *base = host->base;
 	int retries = 10;
@@ -756,6 +758,8 @@ 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_WAITING_FOR_START_IRQ;
+				schedule_delayed_work(&host->ux500_busy_timeout_work,
+				      msecs_to_jiffies(cmd->busy_timeout));
 				goto out_ret_state;
 			}
 			retries--;
@@ -783,6 +787,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 		} else {
 			dev_dbg(mmc_dev(host->mmc),
 				"lost busy status when waiting for busy start IRQ\n");
+			cancel_delayed_work(&host->ux500_busy_timeout_work);
 			ux500_busy_clear_mask_done(host);
 		}
 		break;
@@ -791,6 +796,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
 		if (!(status & host->variant->busy_detect_flag)) {
 			host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND);
 			writel(host->variant->busy_detect_mask, base + MMCICLEAR);
+			cancel_delayed_work(&host->ux500_busy_timeout_work);
 			ux500_busy_clear_mask_done(host);
 		} else {
 			dev_dbg(mmc_dev(host->mmc),
@@ -1307,6 +1313,7 @@ static void
 mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
 {
 	void __iomem *base = host->base;
+	bool busy_resp = cmd->flags & MMC_RSP_BUSY;
 	unsigned long long clks;
 
 	dev_dbg(mmc_dev(host->mmc), "op %02x arg %08x flags %08x\n",
@@ -1334,10 +1341,11 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
 	host->busy_status = 0;
 	host->busy_state = MMCI_BUSY_DONE;
 
-	if (host->variant->busy_timeout && cmd->flags & MMC_RSP_BUSY) {
-		if (!cmd->busy_timeout)
-			cmd->busy_timeout = 10 * MSEC_PER_SEC;
+	/* Assign a default timeout if the core does not provide one */
+	if (busy_resp && !cmd->busy_timeout)
+		cmd->busy_timeout = 10 * MSEC_PER_SEC;
 
+	if (busy_resp && host->variant->busy_timeout) {
 		if (cmd->busy_timeout > host->mmc->max_busy_timeout)
 			clks = (unsigned long long)host->mmc->max_busy_timeout * host->cclk;
 		else
@@ -1478,7 +1486,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
 
 	/* Handle busy detection on DAT0 if the variant supports it. */
 	if (busy_resp && host->variant->busy_detect)
-		if (!host->ops->busy_complete(host, status, err_msk))
+		if (!host->ops->busy_complete(host, cmd, status, err_msk))
 			return;
 
 	host->cmd = NULL;
@@ -1525,6 +1533,34 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
 	}
 }
 
+/*
+ * This busy timeout worker is used to "kick" the command IRQ if a
+ * busy detect IRQ fails to appear in reasonable time. Only used on
+ * variants with busy detection IRQ delivery.
+ */
+static void ux500_busy_timeout_work(struct work_struct *work)
+{
+	struct mmci_host *host = container_of(work, struct mmci_host,
+					ux500_busy_timeout_work.work);
+	unsigned long flags;
+	u32 status;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	if (host->cmd) {
+		dev_dbg(mmc_dev(host->mmc), "timeout waiting for busy IRQ\n");
+
+		/* If we are still busy let's tag on a cmd-timeout error. */
+		status = readl(host->base + MMCISTATUS);
+		if (status & host->variant->busy_detect_flag)
+			status |= MCI_CMDTIMEOUT;
+
+		mmci_cmd_irq(host, host->cmd, status);
+	}
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
 static int mmci_get_rx_fifocnt(struct mmci_host *host, u32 status, int remain)
 {
 	return remain - (readl(host->base + MMCIFIFOCNT) << 2);
@@ -2339,6 +2375,10 @@ static int mmci_probe(struct amba_device *dev,
 			goto clk_disable;
 	}
 
+	if (host->variant->busy_detect)
+		INIT_DELAYED_WORK(&host->ux500_busy_timeout_work,
+				  ux500_busy_timeout_work);
+
 	writel(MCI_IRQENABLE | variant->start_err, host->base + MMCIMASK0);
 
 	amba_set_drvdata(dev, mmc);

drivers/mmc/host/mmci.h

@@ -397,7 +397,7 @@ struct mmci_host_ops {
 	void (*dma_error)(struct mmci_host *host);
 	void (*set_clkreg)(struct mmci_host *host, unsigned int desired);
 	void (*set_pwrreg)(struct mmci_host *host, unsigned int pwr);
-	bool (*busy_complete)(struct mmci_host *host, u32 status, u32 err_msk);
+	bool (*busy_complete)(struct mmci_host *host, struct mmc_command *cmd, u32 status, u32 err_msk);
 	void (*pre_sig_volt_switch)(struct mmci_host *host);
 	int (*post_sig_volt_switch)(struct mmci_host *host, struct mmc_ios *ios);
 };
@@ -455,6 +455,7 @@ struct mmci_host {
 	void			*dma_priv;
 
 	s32			next_cookie;
+	struct delayed_work	ux500_busy_timeout_work;
 };
 
 #define dma_inprogress(host)	((host)->dma_in_progress)

drivers/mmc/host/mmci_stm32_sdmmc.c

@@ -411,7 +411,8 @@ static u32 sdmmc_get_dctrl_cfg(struct mmci_host *host)
 	return datactrl;
 }
 
-static bool sdmmc_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
+static bool sdmmc_busy_complete(struct mmci_host *host, struct mmc_command *cmd,
+				u32 status, u32 err_msk)
 {
 	void __iomem *base = host->base;
 	u32 busy_d0, busy_d0end, mask, sdmmc_status;