[PATCH] mmc: sdhci: supporting PCI MSI

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Enable MSI support in sdhci-pci driver and provide the mechanism
to fall back to Legacy Pin-based Interrupt if MSI register fails.

Signed-off-by: Jackey Shen <Jackey.Shen@xxxxxxx>
Reviewed-by: Huang Rui <ray.huang@xxxxxxx>
---
 drivers/mmc/host/Kconfig  |  11 +++++
 drivers/mmc/host/sdhci.c  | 108 ++++++++++++++++++++++++++++++++++++++++------
 include/linux/mmc/sdhci.h |   2 +
 3 files changed, 109 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 7fc5099..a56cf27 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -68,6 +68,17 @@ config MMC_SDHCI_PCI
 
 	  If unsure, say N.
 
+config MMC_SDHCI_PCI_MSI
+	bool "SDHCI support with MSI on PCI bus"
+	depends on MMC_SDHCI_PCI && PCI_MSI
+	help
+	  This enables PCI MSI (Message Signaled Interrupts) for Secure
+	  Digital Host Controller Interface.
+
+	  If you have a controller with this capability, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_RICOH_MMC
 	bool "Ricoh MMC Controller Disabler"
 	depends on MMC_SDHCI_PCI
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6785fb1..de509bc 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -13,6 +13,10 @@
  *     - JMicron (hardware and technical support)
  */
 
+#ifdef CONFIG_MMC_SDHCI_PCI_MSI
+#include <linux/pci.h>
+#endif
+
 #include <linux/delay.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
@@ -2520,6 +2524,64 @@ out:
 	return result;
 }
 
+#ifdef CONFIG_MMC_SDHCI_PCI_MSI
+static int sdhci_setup_msi(struct sdhci_host *host)
+{
+	int ret;
+	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
+
+	host->msi_enabled = false;
+
+	ret = pci_enable_msi(pdev);
+	if (ret) {
+		pr_warn("%s: Failed to allocate MSI entry\n",
+			mmc_hostname(host->mmc));
+		return ret;
+	}
+
+	ret = request_irq(pdev->irq, sdhci_irq, 0,
+		mmc_hostname(host->mmc), host);
+	if (ret) {
+		pr_warn("%s: Failed to request MSI IRQ %d: %d\n",
+		       mmc_hostname(host->mmc), pdev->irq, ret);
+		pci_disable_msi(pdev);
+		return ret;
+	}
+
+	host->irq = pdev->irq;
+	host->msi_enabled = true;
+	return ret;
+}
+
+static int sdhci_try_enable_msi(struct sdhci_host *host)
+{
+	return sdhci_setup_msi(host);
+}
+
+static void sdhci_cleanup_msi(struct sdhci_host *host)
+{
+	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
+
+	free_irq(host->irq, host);
+	if (host->msi_enabled) {
+		pci_disable_msi(pdev);
+		host->msi_enabled = false;
+	}
+}
+
+#else
+
+static int sdhci_try_enable_msi(struct sdhci_host *host)
+{
+	return 0;
+}
+
+static void sdhci_cleanup_msi(struct sdhci_host *host)
+{
+	free_irq(host->irq, host);
+}
+#endif /* CONFIG_MMC_SDHCI_PCI_MSI */
+
 /*****************************************************************************\
  *                                                                           *
  * Suspend/resume                                                            *
@@ -2569,7 +2631,8 @@ int sdhci_suspend_host(struct sdhci_host *host)
 
 	if (!device_may_wakeup(mmc_dev(host->mmc))) {
 		sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
-		free_irq(host->irq, host);
+		/* free any IRQ and disable MSI */
+		sdhci_cleanup_msi(host);
 	} else {
 		sdhci_enable_irq_wakeups(host);
 		enable_irq_wake(host->irq);
@@ -2589,10 +2652,22 @@ 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);
+		/* try to enable MSI */
+		ret = sdhci_try_enable_msi(host);
 		if (ret)
-			return ret;
+			pr_warn("%s: Fall back to Legacy Pin-based Interrupt: %d\n",
+				mmc_hostname(host->mmc), ret);
+
+		if (!host->msi_enabled) {
+			/* fall back to legacy pin-based interrupt */
+			ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
+					mmc_hostname(host->mmc), host);
+			if (ret) {
+				pr_err("%s: Failed to request IRQ %d: %d\n",
+					 mmc_hostname(host->mmc), host->irq, ret);
+				return ret;
+			}
+		}
 	} else {
 		sdhci_disable_irq_wakeups(host);
 		disable_irq_wake(host->irq);
@@ -3212,12 +3287,21 @@ 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);
-	if (ret) {
-		pr_err("%s: Failed to request IRQ %d: %d\n",
-		       mmc_hostname(mmc), host->irq, ret);
-		goto untasklet;
+	/* try to enable MSI */
+	ret = sdhci_try_enable_msi(host);
+	if (ret)
+		pr_warn("%s: Fall back to Legacy Pin-based Interrupt: %d\n",
+			mmc_hostname(host->mmc), ret);
+
+	if (!host->msi_enabled) {
+		/* fall back to legacy pin-based interrupt */
+		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
+				mmc_hostname(host->mmc), host);
+		if (ret) {
+			pr_err("%s: Failed to request IRQ %d: %d\n",
+				 mmc_hostname(host->mmc), host->irq, ret);
+			goto untasklet;
+		}
 	}
 
 #ifdef CONFIG_MMC_DEBUG
@@ -3257,7 +3341,7 @@ int sdhci_add_host(struct sdhci_host *host)
 reset:
 	sdhci_reset(host, SDHCI_RESET_ALL);
 	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
-	free_irq(host->irq, host);
+	sdhci_cleanup_msi(host);
 #endif
 untasklet:
 	tasklet_kill(&host->card_tasklet);
@@ -3300,7 +3384,7 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
 		sdhci_reset(host, SDHCI_RESET_ALL);
 
 	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
-	free_irq(host->irq, host);
+	sdhci_cleanup_msi(host);
 
 	del_timer_sync(&host->timer);
 
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index 3e781b8..3812479 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -99,6 +99,8 @@ struct sdhci_host {
 /* Controller has a non-standard host control register */
 #define SDHCI_QUIRK2_BROKEN_HOST_CONTROL		(1<<5)
 
+	bool msi_enabled;	/* SD host controller with PCI MSI enabled */
+
 	int irq;		/* Device IRQ */
 	void __iomem *ioaddr;	/* Mapped address */
 
-- 
1.8.1.2


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