[PATCH 2/2] iommu/riscv: Add support for platform msi

[Andrew Jones <ajones@ventanamicro.com>]

Apply platform_device_msi_init_and_alloc_irqs() to add support for
MSIs when the IOMMU is a platform device.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
---
 drivers/iommu/riscv/iommu-platform.c | 102 ++++++++++++++++++++++-----
 1 file changed, 84 insertions(+), 18 deletions(-)

diff --git a/drivers/iommu/riscv/iommu-platform.c b/drivers/iommu/riscv/iommu-platform.c
index da336863f152..89aa622bcbde 100644
--- a/drivers/iommu/riscv/iommu-platform.c
+++ b/drivers/iommu/riscv/iommu-platform.c
@@ -11,18 +11,41 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/msi.h>
 
 #include "iommu-bits.h"
 #include "iommu.h"
 
+static void riscv_iommu_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
+{
+	struct device *dev = msi_desc_to_dev(desc);
+	struct riscv_iommu_device *iommu = dev_get_drvdata(dev);
+	u16 idx = desc->msi_index;
+	u64 addr;
+
+	addr = ((u64)msg->address_hi << 32) | msg->address_lo;
+
+	if (addr != (addr & RISCV_IOMMU_MSI_CFG_TBL_ADDR))
+		pr_warn_once("uh oh, the IOMMU can't send MSIs to 0x%llx, sending to 0x%llx instead\n",
+			     addr, addr & RISCV_IOMMU_MSI_CFG_TBL_ADDR);
+
+	addr &= RISCV_IOMMU_MSI_CFG_TBL_ADDR;
+
+	riscv_iommu_writeq(iommu, RISCV_IOMMU_REG_MSI_CFG_TBL_ADDR(idx), addr);
+	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_MSI_CFG_TBL_DATA(idx), msg->data);
+	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_MSI_CFG_TBL_CTRL(idx), 0);
+}
+
 static int riscv_iommu_platform_probe(struct platform_device *pdev)
 {
+	enum riscv_iommu_igs_settings igs;
 	struct device *dev = &pdev->dev;
 	struct riscv_iommu_device *iommu = NULL;
 	struct resource *res = NULL;
-	int vec;
+	int vec, ret;
 
 	iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
 	if (!iommu)
@@ -40,16 +63,6 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 	iommu->caps = riscv_iommu_readq(iommu, RISCV_IOMMU_REG_CAPABILITIES);
 	iommu->fctl = riscv_iommu_readl(iommu, RISCV_IOMMU_REG_FCTL);
 
-	/* For now we only support WSI */
-	switch (FIELD_GET(RISCV_IOMMU_CAPABILITIES_IGS, iommu->caps)) {
-	case RISCV_IOMMU_CAPABILITIES_IGS_WSI:
-	case RISCV_IOMMU_CAPABILITIES_IGS_BOTH:
-		break;
-	default:
-		return dev_err_probe(dev, -ENODEV,
-				     "unable to use wire-signaled interrupts\n");
-	}
-
 	iommu->irqs_count = platform_irq_count(pdev);
 	if (iommu->irqs_count <= 0)
 		return dev_err_probe(dev, -ENODEV,
@@ -57,13 +70,60 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 	if (iommu->irqs_count > RISCV_IOMMU_INTR_COUNT)
 		iommu->irqs_count = RISCV_IOMMU_INTR_COUNT;
 
-	for (vec = 0; vec < iommu->irqs_count; vec++)
-		iommu->irqs[vec] = platform_get_irq(pdev, vec);
+	igs = FIELD_GET(RISCV_IOMMU_CAPABILITIES_IGS, iommu->caps);
+	switch (igs) {
+	case RISCV_IOMMU_CAPABILITIES_IGS_BOTH:
+	case RISCV_IOMMU_CAPABILITIES_IGS_MSI:
+		if (is_of_node(dev->fwnode))
+			of_msi_configure(dev, to_of_node(dev->fwnode));
+
+		if (!dev_get_msi_domain(dev)) {
+			dev_warn(dev, "failed to find an MSI domain");
+			goto msi_fail;
+		}
+
+		ret = platform_device_msi_init_and_alloc_irqs(dev, iommu->irqs_count,
+							      riscv_iommu_write_msi_msg);
+		if (ret) {
+			dev_warn(dev, "failed to allocate MSIs");
+			goto msi_fail;
+		}
+
+		for (vec = 0; vec < iommu->irqs_count; vec++)
+			iommu->irqs[vec] = msi_get_virq(dev, vec);
+
+		/* Enable message-signaled interrupts, fctl.WSI */
+		if (iommu->fctl & RISCV_IOMMU_FCTL_WSI) {
+			iommu->fctl ^= RISCV_IOMMU_FCTL_WSI;
+			riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL, iommu->fctl);
+		}
+
+		dev_info(dev, "using MSIs\n");
+		break;
+
+msi_fail:
+		if (igs != RISCV_IOMMU_CAPABILITIES_IGS_BOTH) {
+			dev_warn(dev, "\n");
+			return dev_err_probe(dev, -ENODEV,
+					     "unable to use wire-signaled interrupts\n");
+		}
+
+		dev_warn(dev, " - falling back to wired irqs\n");
+		fallthrough;
 
-	/* Enable wire-signaled interrupts, fctl.WSI */
-	if (!(iommu->fctl & RISCV_IOMMU_FCTL_WSI)) {
-		iommu->fctl |= RISCV_IOMMU_FCTL_WSI;
-		riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL, iommu->fctl);
+	case RISCV_IOMMU_CAPABILITIES_IGS_WSI:
+		for (vec = 0; vec < iommu->irqs_count; vec++)
+			iommu->irqs[vec] = platform_get_irq(pdev, vec);
+
+		/* Enable wire-signaled interrupts, fctl.WSI */
+		if (!(iommu->fctl & RISCV_IOMMU_FCTL_WSI)) {
+			iommu->fctl |= RISCV_IOMMU_FCTL_WSI;
+			riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL, iommu->fctl);
+		}
+		dev_info(dev, "using wire-signaled interrupts\n");
+		break;
+	default:
+		return dev_err_probe(dev, -ENODEV, "invalid IGS\n");
 	}
 
 	return riscv_iommu_init(iommu);
@@ -71,7 +131,13 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 
 static void riscv_iommu_platform_remove(struct platform_device *pdev)
 {
-	riscv_iommu_remove(dev_get_drvdata(&pdev->dev));
+	struct riscv_iommu_device *iommu = dev_get_drvdata(&pdev->dev);
+	bool msi = !(iommu->fctl & RISCV_IOMMU_FCTL_WSI);
+
+	riscv_iommu_remove(iommu);
+
+	if (msi)
+		platform_device_msi_free_irqs_all(&pdev->dev);
 };
 
 static const struct of_device_id riscv_iommu_of_match[] = {
-- 
2.47.0