irqchip/riscv-imsic: Add device MSI domain support for PCI devices

The Linux PCI framework supports per-device MSI domains for PCI devices
so extend the IMSIC driver to allow PCI per-device MSI domains.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240307140307.646078-5-apatel@ventanamicro.com

drivers/irqchip/Kconfig

@@ -547,6 +547,13 @@ config RISCV_IMSIC
 	select GENERIC_IRQ_MATRIX_ALLOCATOR
 	select GENERIC_MSI_IRQ
 
+config RISCV_IMSIC_PCI
+	bool
+	depends on RISCV_IMSIC
+	depends on PCI
+	depends on PCI_MSI
+	default RISCV_IMSIC
+
 config SIFIVE_PLIC
 	bool
 	depends on RISCV

drivers/irqchip/irq-riscv-imsic-platform.c

@@ -14,6 +14,7 @@
 #include <linux/irqdomain.h>
 #include <linux/module.h>
 #include <linux/msi.h>
+#include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/smp.h>
@@ -207,6 +208,28 @@ static const struct irq_domain_ops imsic_base_domain_ops = {
 #endif
 };
 
+#ifdef CONFIG_RISCV_IMSIC_PCI
+
+static void imsic_pci_mask_irq(struct irq_data *d)
+{
+	pci_msi_mask_irq(d);
+	irq_chip_mask_parent(d);
+}
+
+static void imsic_pci_unmask_irq(struct irq_data *d)
+{
+	irq_chip_unmask_parent(d);
+	pci_msi_unmask_irq(d);
+}
+
+#define MATCH_PCI_MSI		BIT(DOMAIN_BUS_PCI_MSI)
+
+#else
+
+#define MATCH_PCI_MSI		0
+
+#endif
+
 static bool imsic_init_dev_msi_info(struct device *dev,
 				    struct irq_domain *domain,
 				    struct irq_domain *real_parent,
@@ -230,6 +253,13 @@ static bool imsic_init_dev_msi_info(struct device *dev,
 
 	/* Is the target supported? */
 	switch (info->bus_token) {
+#ifdef CONFIG_RISCV_IMSIC_PCI
+	case DOMAIN_BUS_PCI_DEVICE_MSI:
+	case DOMAIN_BUS_PCI_DEVICE_MSIX:
+		info->chip->irq_mask = imsic_pci_mask_irq;
+		info->chip->irq_unmask = imsic_pci_unmask_irq;
+		break;
+#endif
 	case DOMAIN_BUS_DEVICE_MSI:
 		/*
 		 * Per-device MSI should never have any MSI feature bits
@@ -269,11 +299,12 @@ static bool imsic_init_dev_msi_info(struct device *dev,
 #define MATCH_PLATFORM_MSI		BIT(DOMAIN_BUS_PLATFORM_MSI)
 
 static const struct msi_parent_ops imsic_msi_parent_ops = {
-	.supported_flags	= MSI_GENERIC_FLAGS_MASK,
+	.supported_flags	= MSI_GENERIC_FLAGS_MASK |
+				  MSI_FLAG_PCI_MSIX,
 	.required_flags		= MSI_FLAG_USE_DEF_DOM_OPS |
 				  MSI_FLAG_USE_DEF_CHIP_OPS,
 	.bus_select_token	= DOMAIN_BUS_NEXUS,
-	.bus_select_mask	= MATCH_PLATFORM_MSI,
+	.bus_select_mask	= MATCH_PCI_MSI | MATCH_PLATFORM_MSI,
 	.init_dev_msi_info	= imsic_init_dev_msi_info,
 };