mmc: sdhci: convert to new SDIO IRQ handling

Use a generic threaded interrupt handler for SDIO interrupt handling,
rather than allowing the SDIO core code to buggily spawn its own
thread.  This results in host drivers to be more in control of how
SDIO interrupts are acknowledged in the hardware, rather than having
the internals of the SDIO core placed upon them, possibly resulting
in sub-standard handling.

At least one SDHCI implementation specifies a very specific sequence
to deal with a card interrupt.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Markus Pargmann <mpa@pengutronix.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>

Author: Russell King

drivers/mmc/host/sdhci.c

@@ -2428,10 +2428,10 @@ static void sdhci_data_irq(struct sdhci_host *host, u32 intmask)
 
 static irqreturn_t sdhci_irq(int irq, void *dev_id)
 {
-	irqreturn_t result;
+	irqreturn_t result = IRQ_NONE;
 	struct sdhci_host *host = dev_id;
 	u32 intmask, mask, unexpected = 0;
-	int cardint = 0, max_loops = 16;
+	int max_loops = 16;
 
 	spin_lock(&host->lock);
 
@@ -2490,8 +2490,11 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 			pr_err("%s: Card is consuming too much power!\n",
 				mmc_hostname(host->mmc));
 
-		if (intmask & SDHCI_INT_CARD_INT)
-			cardint = 1;
+		if (intmask & SDHCI_INT_CARD_INT) {
+			sdhci_enable_sdio_irq_nolock(host, false);
+			host->thread_isr |= SDHCI_INT_CARD_INT;
+			result = IRQ_WAKE_THREAD;
+		}
 
 		intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE |
 			     SDHCI_INT_CMD_MASK | SDHCI_INT_DATA_MASK |
@@ -2503,17 +2506,10 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 			sdhci_writel(host, intmask, SDHCI_INT_STATUS);
 		}
 
-		result = IRQ_HANDLED;
+		if (result == IRQ_NONE)
+			result = IRQ_HANDLED;
 
 		intmask = sdhci_readl(host, SDHCI_INT_STATUS);
-
-		/*
-		 * If we know we'll call the driver to signal SDIO IRQ,
-		 * disregard further indications of Card Interrupt in
-		 * the status to avoid a needless loop.
-		 */
-		if (cardint)
-			intmask &= ~SDHCI_INT_CARD_INT;
 	} while (intmask && --max_loops);
 out:
 	spin_unlock(&host->lock);
@@ -2523,15 +2519,33 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 			   mmc_hostname(host->mmc), unexpected);
 		sdhci_dumpregs(host);
 	}
-	/*
-	 * We have to delay this as it calls back into the driver.
-	 */
-	if (cardint)
-		mmc_signal_sdio_irq(host->mmc);
 
 	return result;
 }
 
+static irqreturn_t sdhci_thread_irq(int irq, void *dev_id)
+{
+	struct sdhci_host *host = dev_id;
+	unsigned long flags;
+	u32 isr;
+
+	spin_lock_irqsave(&host->lock, flags);
+	isr = host->thread_isr;
+	host->thread_isr = 0;
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (isr & SDHCI_INT_CARD_INT) {
+		sdio_run_irqs(host->mmc);
+
+		spin_lock_irqsave(&host->lock, flags);
+		if (host->flags & SDHCI_SDIO_IRQ_ENABLED)
+			sdhci_enable_sdio_irq_nolock(host, true);
+		spin_unlock_irqrestore(&host->lock, flags);
+	}
+
+	return isr ? IRQ_HANDLED : IRQ_NONE;
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Suspend/resume                                                            *
@@ -2601,8 +2615,9 @@ int sdhci_resume_host(struct sdhci_host *host)
 	}
 
 	if (!device_may_wakeup(mmc_dev(host->mmc))) {
-		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
-				  mmc_hostname(host->mmc), host);
+		ret = request_threaded_irq(host->irq, sdhci_irq,
+					   sdhci_thread_irq, IRQF_SHARED,
+					   mmc_hostname(host->mmc), host);
 		if (ret)
 			return ret;
 	} else {
@@ -2681,7 +2696,7 @@ int sdhci_runtime_suspend_host(struct sdhci_host *host)
 	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
 	spin_unlock_irqrestore(&host->lock, flags);
 
-	synchronize_irq(host->irq);
+	synchronize_hardirq(host->irq);
 
 	spin_lock_irqsave(&host->lock, flags);
 	host->runtime_suspended = true;
@@ -2937,6 +2952,7 @@ int sdhci_add_host(struct sdhci_host *host)
 	mmc->max_busy_timeout = (1 << 27) / host->timeout_clk;
 
 	mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
+	mmc->caps2 |= MMC_CAP2_SDIO_IRQ_NOTHREAD;
 
 	if (host->quirks & SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12)
 		host->flags |= SDHCI_AUTO_CMD12;
@@ -3226,8 +3242,8 @@ int sdhci_add_host(struct sdhci_host *host)
 
 	sdhci_init(host, 0);
 
-	ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
-		mmc_hostname(mmc), host);
+	ret = request_threaded_irq(host->irq, sdhci_irq, sdhci_thread_irq,
+				   IRQF_SHARED,	mmc_hostname(mmc), host);
 	if (ret) {
 		pr_err("%s: Failed to request IRQ %d: %d\n",
 		       mmc_hostname(mmc), host->irq, ret);

include/linux/mmc/sdhci.h

@@ -177,6 +177,8 @@ struct sdhci_host {
 	unsigned int            ocr_avail_mmc;
 	u32 ocr_mask;		/* available voltages */
 
+	u32			thread_isr;
+
 	wait_queue_head_t	buf_ready_int;	/* Waitqueue for Buffer Read Ready interrupt */
 	unsigned int		tuning_done;	/* Condition flag set when CMD19 succeeds */