bus/cdx: add cdx-MSI domain with gic-its domain as parent

Since CDX devices are not linked to of node they need a
separate MSI domain for handling device ID to be provided to
the GIC ITS domain.

This also introduces APIs to alloc and free IRQs for CDX domain.

Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Nikhil Agarwal <nikhil.agarwal@amd.com>

drivers/bus/cdx/Kconfig

@@ -7,6 +7,7 @@
 
 config CDX_BUS
 	bool "CDX Bus driver"
+	select GENERIC_MSI_IRQ_DOMAIN
 	help
 		Driver to enable CDX Bus infrastructure. CDX bus uses
 		CDX controller and firmware to scan the FPGA based

drivers/bus/cdx/Makefile

@@ -5,4 +5,4 @@
 # Copyright (C) 2022, Advanced Micro Devices, Inc.
 #
 
-obj-$(CONFIG_CDX_BUS) += cdx.o
+obj-$(CONFIG_CDX_BUS) += cdx.o cdx_msi.o

drivers/bus/cdx/cdx.c

@@ -56,6 +56,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/of_device.h>
 #include <linux/slab.h>
@@ -449,6 +450,7 @@ int cdx_device_add(struct cdx_dev_params_t *dev_params)
 	struct cdx_controller_t *cdx = dev_params->cdx;
 	struct device *parent = cdx->dev;
 	struct cdx_device *cdx_dev;
+	struct irq_domain *cdx_msi_domain;
 	int ret;
 
 	cdx_dev = kzalloc(sizeof(*cdx_dev), GFP_KERNEL);
@@ -465,6 +467,7 @@ int cdx_device_add(struct cdx_dev_params_t *dev_params)
 
 	/* Populate CDX dev params */
 	cdx_dev->req_id = dev_params->req_id;
+	cdx_dev->num_msi = dev_params->num_msi;
 	cdx_dev->vendor = dev_params->vendor;
 	cdx_dev->device = dev_params->device;
 	cdx_dev->bus_num = dev_params->bus_num;
@@ -483,6 +486,21 @@ int cdx_device_add(struct cdx_dev_params_t *dev_params)
 	dev_set_name(&cdx_dev->dev, "cdx-%02x:%02x", cdx_dev->bus_num,
 			cdx_dev->dev_num);
 
+	/* If CDX MSI domain is not created, create one. */
+	cdx_msi_domain = irq_find_host(parent->of_node);
+	if (!cdx_msi_domain) {
+		cdx_msi_domain = cdx_msi_domain_init(parent);
+		if (!cdx_msi_domain) {
+			dev_err(&cdx_dev->dev,
+				"cdx_msi_domain_init() failed: %d", ret);
+			kfree(cdx_dev);
+			return -ENODEV;
+		}
+	}
+
+	/* Set the MSI domain */
+	dev_set_msi_domain(&cdx_dev->dev, cdx_msi_domain);
+
 	ret = device_add(&cdx_dev->dev);
 	if (ret != 0) {
 		dev_err(&cdx_dev->dev,

drivers/bus/cdx/cdx.h

@@ -23,6 +23,7 @@
  * @res: array of MMIO region entries
  * @res_count: number of valid MMIO regions
  * @req_id: Requestor ID associated with CDX device
+ * @num_msi: Number of MSI's supported by the device
  */
 struct cdx_dev_params_t {
 	struct cdx_controller_t *cdx;
@@ -35,6 +36,7 @@ struct cdx_dev_params_t {
 	struct resource res[MAX_CDX_DEV_RESOURCES];
 	u8 res_count;
 	u32 req_id;
+	u32 num_msi;
 };
 
 /**
@@ -63,4 +65,12 @@ void cdx_unregister_controller(struct cdx_controller_t *cdx);
  */
 int cdx_device_add(struct cdx_dev_params_t *dev_params);
 
+/**
+ * cdx_msi_domain_init - Init the CDX bus MSI domain.
+ * @dev: Device of the CDX bus controller
+ *
+ * Return CDX MSI domain, NULL on failure
+ */
+struct irq_domain *cdx_msi_domain_init(struct device *dev);
+
 #endif /* _CDX_H_ */

drivers/bus/cdx/cdx_msi.c

@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD CDX bus driver MSI support
+ *
+ * Copyright (C) 2022, Advanced Micro Devices, Inc.
+ *
+ */
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/msi.h>
+#include <linux/cdx/cdx_bus.h>
+
+#include "cdx.h"
+
+#define REQ_ID_SHIFT	10
+
+/*
+ * Convert an msi_desc to a globaly unique identifier (per-device
+ * reqid + msi_desc position in the msi_list).
+ */
+static irq_hw_number_t cdx_domain_calc_hwirq(struct cdx_device *dev,
+					     struct msi_desc *desc)
+{
+	return (dev->req_id << REQ_ID_SHIFT) | desc->msi_index;
+}
+
+static void cdx_msi_set_desc(msi_alloc_info_t *arg,
+			     struct msi_desc *desc)
+{
+	arg->desc = desc;
+	arg->hwirq = cdx_domain_calc_hwirq(to_cdx_device(desc->dev), desc);
+}
+
+static void cdx_msi_write_msg(struct irq_data *irq_data,
+			      struct msi_msg *msg)
+{
+	struct msi_desc *msi_desc = irq_data_get_msi_desc(irq_data);
+	struct cdx_device *cdx_dev = to_cdx_device(msi_desc->dev);
+	struct cdx_controller_t *cdx = cdx_dev->cdx;
+	uint64_t addr;
+	int ret;
+
+	addr = ((uint64_t)(msi_desc->msg.address_hi) << 32) |
+	       msi_desc->msg.address_lo;
+
+	ret = cdx->ops.write_msi(cdx, cdx_dev->bus_num, cdx_dev->dev_num,
+				 msi_desc->msi_index, msi_desc->msg.data,
+				 addr);
+	if (ret)
+		dev_err(&cdx_dev->dev, "Write MSI failed to CDX controller\n");
+}
+
+int cdx_msi_domain_alloc_irqs(struct device *dev, unsigned int irq_count)
+{
+	int ret;
+
+	ret = msi_setup_device_data(dev);
+	if (ret)
+		return ret;
+
+	msi_lock_descs(dev);
+	if (msi_first_desc(dev, MSI_DESC_ALL))
+		ret = -EINVAL;
+	msi_unlock_descs(dev);
+	if (ret)
+		return ret;
+
+	ret = msi_domain_alloc_irqs(dev, irq_count);
+	if (ret)
+		dev_err(dev, "Failed to allocate IRQs\n");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cdx_msi_domain_alloc_irqs);
+
+static struct irq_chip cdx_msi_irq_chip = {
+	.name			= "CDX-MSI",
+	.irq_mask		= irq_chip_mask_parent,
+	.irq_unmask		= irq_chip_unmask_parent,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_set_affinity	= msi_domain_set_affinity,
+	.irq_write_msi_msg	= cdx_msi_write_msg
+};
+
+static int cdx_msi_prepare(struct irq_domain *msi_domain,
+			   struct device *dev,
+			   int nvec, msi_alloc_info_t *info)
+{
+	struct cdx_device *cdx_dev = to_cdx_device(dev);
+	struct msi_domain_info *msi_info;
+	struct device *parent = dev->parent;
+	u32 dev_id;
+	int ret;
+
+	/* Retrieve device ID from requestor ID using parent device */
+	ret = of_map_id(parent->of_node, cdx_dev->req_id, "msi-map",
+			"msi-map-mask",	NULL, &dev_id);
+	if (ret) {
+		dev_err(dev, "of_map_id failed for MSI: %d\n", ret);
+		return ret;
+	}
+
+	/* Set the device Id to be passed to the GIC-ITS */
+	info->scratchpad[0].ul = dev_id;
+
+	msi_info = msi_get_domain_info(msi_domain->parent);
+
+	return msi_info->ops->msi_prepare(msi_domain->parent, dev, nvec, info);
+}
+
+static struct msi_domain_ops cdx_msi_ops __ro_after_init = {
+	.msi_prepare	= cdx_msi_prepare,
+	.set_desc	= cdx_msi_set_desc
+};
+
+static struct msi_domain_info cdx_msi_domain_info = {
+	.ops	= &cdx_msi_ops,
+	.chip	= &cdx_msi_irq_chip,
+	.flags	= MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		  MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS | MSI_FLAG_FREE_MSI_DESCS
+};
+
+struct irq_domain *cdx_msi_domain_init(struct device *dev)
+{
+	struct irq_domain *parent;
+	struct irq_domain *cdx_msi_domain;
+	struct fwnode_handle *fwnode_handle;
+	struct device_node *parent_node;
+	struct device_node *np = dev->of_node;
+
+	fwnode_handle = of_node_to_fwnode(np);
+
+	parent_node = of_parse_phandle(np, "msi-map", 1);
+	if (!parent_node) {
+		dev_err(dev, "msi-map not present on cdx controller\n");
+		return NULL;
+	}
+
+	parent = irq_find_matching_fwnode(of_node_to_fwnode(parent_node),
+			DOMAIN_BUS_NEXUS);
+	if (!parent || !msi_get_domain_info(parent)) {
+		dev_err(dev, "unable to locate ITS domain\n");
+		return NULL;
+	}
+
+	cdx_msi_domain = msi_create_irq_domain(fwnode_handle,
+				&cdx_msi_domain_info, parent);
+	if (!cdx_msi_domain) {
+		dev_err(dev, "unable to create CDX-MSI domain\n");
+		return NULL;
+	}
+
+	dev_dbg(dev, "CDX-MSI domain created\n");
+
+	return cdx_msi_domain;
+}

include/linux/cdx/cdx_bus.h

@@ -21,14 +21,21 @@ typedef int (*cdx_scan_t)(struct cdx_controller_t *cdx);
 typedef int (*cdx_dev_reset_t)(struct cdx_controller_t *cdx,
 			       uint8_t bus_num, uint8_t dev_num);
 
+typedef int (*cdx_write_msi_msg_t)(struct cdx_controller_t *cdx,
+				   uint8_t bus_num, uint8_t dev_num,
+				   uint16_t msi_index, uint32_t data,
+				   uint64_t addr);
+
 /**
  * Callbacks supported by CDX controller.
  * @scan: scan the devices on the controller
  * @reset_dev: reset a CDX device
+ * @write_msi: callback to write the MSI message
  */
 struct cdx_ops_t {
 	cdx_scan_t scan;
 	cdx_dev_reset_t reset_dev;
+	cdx_write_msi_msg_t write_msi;
 };
 
 /**
@@ -57,6 +64,7 @@ struct cdx_controller_t {
  * @dma_mask: Default DMA mask
  * @flags: CDX device flags
  * @req_id: Requestor ID associated with CDX device
+ * @num_msi: Number of MSI's supported by the device
  * @driver_override: driver name to force a match; do not set directly,
  *                   because core frees it; use driver_set_override() to
  *                   set or clear it.
@@ -73,6 +81,7 @@ struct cdx_device {
 	u64 dma_mask;
 	u16 flags;
 	u32 req_id;
+	u32 num_msi;
 	const char *driver_override;
 };
 
@@ -136,4 +145,21 @@ extern struct bus_type cdx_bus_type;
  */
 int cdx_dev_reset(struct device *dev);
 
+/**
+ * cdx_msi_domain_alloc_irqs - Allocate MSI's for the CDX device
+ * @dev: device pointer
+ * @irq_count: Number of MSI's to be allocated
+ *
+ * Return 0 for success, -errno on failure
+ */
+int cdx_msi_domain_alloc_irqs(struct device *dev, unsigned int irq_count);
+
+/**
+ * cdx_msi_domain_free_irqs - Free MSI's for CDX device
+ * @dev: device pointer
+ *
+ * Return 0 for success, -errno on failure
+ */
+#define cdx_msi_domain_free_irqs msi_domain_free_irqs
+
 #endif /* _CDX_BUS_H_ */

kernel/irq/msi.c

@@ -1034,6 +1034,7 @@ void msi_domain_free_irqs(struct device *dev)
 	msi_domain_free_irqs_descs_locked(dev);
 	msi_unlock_descs(dev);
 }
+EXPORT_SYMBOL_GPL(msi_domain_free_irqs);
 
 /**
  * msi_get_domain_info - Get the MSI interrupt domain info for @domain