mmc: dw_mmc: Convert to use MMC_CAP2_SDIO_IRQ_NOTHREAD for SDIO IRQs

Convert to use the more lightweight method for processing SDIO IRQs, which
involves the following changes:

- Enable MMC_CAP2_SDIO_IRQ_NOTHREAD when SDIO IRQ is supported and use
  sdio_signal_irq() instead of mmc_signal_sdio_irq().
- Mask the SDIO IRQ before signaling a new one to be processed.
- Implement the ->ack_sdio_irq() callback to unmask the SDIO IRQ.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

drivers/mmc/host/dw_mmc.c

@@ -1642,9 +1642,8 @@ static void dw_mci_init_card(struct mmc_host *mmc, struct mmc_card *card)
 	}
 }
 
-static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
+static void __dw_mci_enable_sdio_irq(struct dw_mci_slot *slot, int enb)
 {
-	struct dw_mci_slot *slot = mmc_priv(mmc);
 	struct dw_mci *host = slot->host;
 	unsigned long irqflags;
 	u32 int_mask;
@@ -1662,6 +1661,20 @@ static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
 	spin_unlock_irqrestore(&host->irq_lock, irqflags);
 }
 
+static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
+{
+	struct dw_mci_slot *slot = mmc_priv(mmc);
+
+	__dw_mci_enable_sdio_irq(slot, enb);
+}
+
+static void dw_mci_ack_sdio_irq(struct mmc_host *mmc)
+{
+	struct dw_mci_slot *slot = mmc_priv(mmc);
+
+	__dw_mci_enable_sdio_irq(slot, 1);
+}
+
 static int dw_mci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 {
 	struct dw_mci_slot *slot = mmc_priv(mmc);
@@ -1763,6 +1776,7 @@ static const struct mmc_host_ops dw_mci_ops = {
 	.get_cd			= dw_mci_get_cd,
 	.hw_reset               = dw_mci_hw_reset,
 	.enable_sdio_irq	= dw_mci_enable_sdio_irq,
+	.ack_sdio_irq		= dw_mci_ack_sdio_irq,
 	.execute_tuning		= dw_mci_execute_tuning,
 	.card_busy		= dw_mci_card_busy,
 	.start_signal_voltage_switch = dw_mci_switch_voltage,
@@ -2654,7 +2668,8 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
 			if (pending & SDMMC_INT_SDIO(slot->sdio_id)) {
 				mci_writel(host, RINTSTS,
 					   SDMMC_INT_SDIO(slot->sdio_id));
-				mmc_signal_sdio_irq(slot->mmc);
+				__dw_mci_enable_sdio_irq(slot, 0);
+				sdio_signal_irq(slot->mmc);
 			}
 		}
 
@@ -2755,6 +2770,10 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
 	if (ret)
 		goto err_host_allocated;
 
+	/* Process SDIO IRQs through the sdio_irq_work. */
+	if (mmc->caps & MMC_CAP_SDIO_IRQ)
+		mmc->caps2 |= MMC_CAP2_SDIO_IRQ_NOTHREAD;
+
 	/* Useful defaults if platform data is unset. */
 	if (host->use_dma == TRANS_MODE_IDMAC) {
 		mmc->max_segs = host->ring_size;