[PATCH v2 3/5] virtio-mmio: create a generic MSI irq domain

[Zha Bin <zhabin@linux.alibaba.com>]

From: Liu Jiang <gerry@linux.alibaba.com>

Create a generic irq domain for all architectures which
supports virtio-mmio. The device offering VIRTIO_F_MMIO_MSI
feature bit can use this irq domain.

Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>
Co-developed-by: Zha Bin <zhabin@linux.alibaba.com>
Signed-off-by: Zha Bin <zhabin@linux.alibaba.com>
Co-developed-by: Jing Liu <jing2.liu@linux.intel.com>
Signed-off-by: Jing Liu <jing2.liu@linux.intel.com>
Co-developed-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 drivers/base/platform-msi.c      |  4 +-
 drivers/virtio/Kconfig           |  9 ++++
 drivers/virtio/virtio_mmio_msi.h | 93 ++++++++++++++++++++++++++++++++++++++++
 include/linux/msi.h              |  1 +
 4 files changed, 105 insertions(+), 2 deletions(-)
 create mode 100644 drivers/virtio/virtio_mmio_msi.h

diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c
index 8da314b..45752f1 100644
--- a/drivers/base/platform-msi.c
+++ b/drivers/base/platform-msi.c
@@ -31,12 +31,11 @@ struct platform_msi_priv_data {
 /* The devid allocator */
 static DEFINE_IDA(platform_msi_devid_ida);
 
-#ifdef GENERIC_MSI_DOMAIN_OPS
 /*
  * Convert an msi_desc to a globaly unique identifier (per-device
  * devid + msi_desc position in the msi_list).
  */
-static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
+irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
 {
 	u32 devid;
 
@@ -45,6 +44,7 @@ static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
 	return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
 }
 
+#ifdef GENERIC_MSI_DOMAIN_OPS
 static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
 {
 	arg->desc = desc;
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 078615c..551a9f7 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -84,6 +84,15 @@ config VIRTIO_MMIO
 
  	 If unsure, say N.
 
+config VIRTIO_MMIO_MSI
+	bool "Memory-mapped virtio device MSI"
+	depends on VIRTIO_MMIO && GENERIC_MSI_IRQ_DOMAIN && GENERIC_MSI_IRQ
+	help
+	 This allows device drivers to support msi interrupt handling for
+	 virtio-mmio devices. It can improve performance greatly.
+
+	 If unsure, say N.
+
 config VIRTIO_MMIO_CMDLINE_DEVICES
 	bool "Memory mapped virtio devices parameter parsing"
 	depends on VIRTIO_MMIO
diff --git a/drivers/virtio/virtio_mmio_msi.h b/drivers/virtio/virtio_mmio_msi.h
new file mode 100644
index 0000000..27cb2af
--- /dev/null
+++ b/drivers/virtio/virtio_mmio_msi.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _DRIVERS_VIRTIO_VIRTIO_MMIO_MSI_H
+#define _DRIVERS_VIRTIO_VIRTIO_MMIO_MSI_H
+
+#ifdef CONFIG_VIRTIO_MMIO_MSI
+
+#include <linux/msi.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/platform_device.h>
+
+static irq_hw_number_t mmio_msi_hwirq;
+static struct irq_domain *mmio_msi_domain;
+
+struct irq_domain *__weak arch_msi_root_irq_domain(void)
+{
+	return NULL;
+}
+
+void __weak irq_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
+{
+}
+
+static void mmio_msi_mask_irq(struct irq_data *data)
+{
+}
+
+static void mmio_msi_unmask_irq(struct irq_data *data)
+{
+}
+
+static struct irq_chip mmio_msi_controller = {
+	.name			= "VIRTIO-MMIO-MSI",
+	.irq_mask		= mmio_msi_mask_irq,
+	.irq_unmask		= mmio_msi_unmask_irq,
+	.irq_ack		= irq_chip_ack_parent,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
+	.irq_compose_msi_msg	= irq_msi_compose_msg,
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
+};
+
+static int mmio_msi_prepare(struct irq_domain *domain, struct device *dev,
+				int nvec, msi_alloc_info_t *arg)
+{
+	memset(arg, 0, sizeof(*arg));
+	return 0;
+}
+
+static void mmio_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
+{
+	mmio_msi_hwirq = platform_msi_calc_hwirq(desc);
+}
+
+static irq_hw_number_t mmio_msi_get_hwirq(struct msi_domain_info *info,
+					      msi_alloc_info_t *arg)
+{
+	return mmio_msi_hwirq;
+}
+
+static struct msi_domain_ops mmio_msi_domain_ops = {
+	.msi_prepare	= mmio_msi_prepare,
+	.set_desc	= mmio_msi_set_desc,
+	.get_hwirq	= mmio_msi_get_hwirq,
+};
+
+static struct msi_domain_info mmio_msi_domain_info = {
+	.flags          = MSI_FLAG_USE_DEF_DOM_OPS |
+			  MSI_FLAG_USE_DEF_CHIP_OPS |
+			  MSI_FLAG_ACTIVATE_EARLY,
+	.ops            = &mmio_msi_domain_ops,
+	.chip           = &mmio_msi_controller,
+	.handler        = handle_edge_irq,
+	.handler_name   = "edge",
+};
+
+static inline void mmio_msi_create_irq_domain(void)
+{
+	struct fwnode_handle *fn;
+	struct irq_domain *parent = arch_msi_root_irq_domain();
+
+	fn = irq_domain_alloc_named_fwnode("VIRTIO-MMIO-MSI");
+	if (fn && parent) {
+		mmio_msi_domain =
+			platform_msi_create_irq_domain(fn,
+				&mmio_msi_domain_info, parent);
+		irq_domain_free_fwnode(fn);
+	}
+}
+#else
+static inline void mmio_msi_create_irq_domain(void) {}
+#endif
+
+#endif
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 8ad679e..ee5f566 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -362,6 +362,7 @@ int platform_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
 void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq,
 			      unsigned int nvec);
 void *platform_msi_get_host_data(struct irq_domain *domain);
+irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc);
 #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */
 
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
-- 
1.8.3.1