[PATCH v5 5/9] irqchip/riscv-imsic: Add support for PCI MSI irqdomain

[Anup Patel <apatel@xxxxxxxxxxxxxxxx>]

The Linux PCI framework requires it's own dedicated MSI irqdomain so
let us create PCI MSI irqdomain as child of the IMSIC base irqdomain.

Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
---
 drivers/irqchip/Kconfig           |  7 +++++
 drivers/irqchip/irq-riscv-imsic.c | 49 +++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 8ef18be5f37b..d700980372ef 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -550,6 +550,13 @@ config RISCV_IMSIC
 	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_MSI_IRQ
 
+config RISCV_IMSIC_PCI
+	bool
+	depends on RISCV_IMSIC
+	depends on PCI
+	depends on PCI_MSI
+	default RISCV_IMSIC
+
 config EXYNOS_IRQ_COMBINER
 	bool "Samsung Exynos IRQ combiner support" if COMPILE_TEST
 	depends on (ARCH_EXYNOS && ARM) || COMPILE_TEST
diff --git a/drivers/irqchip/irq-riscv-imsic.c b/drivers/irqchip/irq-riscv-imsic.c
index ceb5e0fc883c..061bba1b69a2 100644
--- a/drivers/irqchip/irq-riscv-imsic.c
+++ b/drivers/irqchip/irq-riscv-imsic.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/of_address.h>
+#include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/smp.h>
@@ -80,6 +81,7 @@ struct imsic_priv {
 
 	/* IRQ domains */
 	struct irq_domain *base_domain;
+	struct irq_domain *pci_domain;
 	struct irq_domain *plat_domain;
 };
 
@@ -530,6 +532,39 @@ static const struct irq_domain_ops imsic_base_domain_ops = {
 	.free		= imsic_irq_domain_free,
 };
 
+#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)
+{
+	pci_msi_unmask_irq(d);
+	irq_chip_unmask_parent(d);
+}
+
+static struct irq_chip imsic_pci_irq_chip = {
+	.name			= "RISC-V IMSIC-PCI",
+	.irq_mask		= imsic_pci_mask_irq,
+	.irq_unmask		= imsic_pci_unmask_irq,
+	.irq_eoi		= irq_chip_eoi_parent,
+};
+
+static struct msi_domain_ops imsic_pci_domain_ops = {
+};
+
+static struct msi_domain_info imsic_pci_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		   MSI_FLAG_PCI_MSIX | MSI_FLAG_MULTI_PCI_MSI),
+	.ops	= &imsic_pci_domain_ops,
+	.chip	= &imsic_pci_irq_chip,
+};
+
+#endif
+
 static struct irq_chip imsic_plat_irq_chip = {
 	.name			= "RISC-V IMSIC-PLAT",
 };
@@ -554,12 +589,26 @@ static int __init imsic_irq_domains_init(struct fwnode_handle *fwnode)
 	}
 	irq_domain_update_bus_token(imsic->base_domain, DOMAIN_BUS_NEXUS);
 
+#ifdef CONFIG_RISCV_IMSIC_PCI
+	/* Create PCI MSI domain */
+	imsic->pci_domain = pci_msi_create_irq_domain(fwnode,
+						&imsic_pci_domain_info,
+						imsic->base_domain);
+	if (!imsic->pci_domain) {
+		pr_err("Failed to create IMSIC PCI domain\n");
+		irq_domain_remove(imsic->base_domain);
+		return -ENOMEM;
+	}
+#endif
+
 	/* Create Platform MSI domain */
 	imsic->plat_domain = platform_msi_create_irq_domain(fwnode,
 						&imsic_plat_domain_info,
 						imsic->base_domain);
 	if (!imsic->plat_domain) {
 		pr_err("Failed to create IMSIC platform domain\n");
+		if (imsic->pci_domain)
+			irq_domain_remove(imsic->pci_domain);
 		irq_domain_remove(imsic->base_domain);
 		return -ENOMEM;
 	}
-- 
2.34.1