[RFC PATCH v2 3/6] bus/cdx: add cdx-MSI domain with gic-its domain as parent

[Nipun Gupta <nipun.gupta@amd.com>]

Devices on cdx bus are dynamically detected and registered using
platform_device_register API. As these 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.

Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
---
 drivers/bus/cdx/Makefile         |  2 +-
 drivers/bus/cdx/cdx.c            | 31 +++++++++++
 drivers/bus/cdx/cdx.h            | 16 ++++++
 drivers/bus/cdx/cdx_msi_domain.c | 90 ++++++++++++++++++++++++++++++++
 4 files changed, 138 insertions(+), 1 deletion(-)
 create mode 100644 drivers/bus/cdx/cdx_msi_domain.c

diff --git a/drivers/bus/cdx/Makefile b/drivers/bus/cdx/Makefile
index c9cee5b6fa8a..5dc7874530f5 100644
--- a/drivers/bus/cdx/Makefile
+++ b/drivers/bus/cdx/Makefile
@@ -1,3 +1,3 @@
 obj-$(CONFIG_CDX_BUS) += cdx-bus-device-driver.o
 
-cdx-bus-device-driver-objs := cdx.o
+cdx-bus-device-driver-objs := cdx.o cdx_msi_domain.o
diff --git a/drivers/bus/cdx/cdx.c b/drivers/bus/cdx/cdx.c
index f28329770af8..cd916ef5f2bc 100644
--- a/drivers/bus/cdx/cdx.c
+++ b/drivers/bus/cdx/cdx.c
@@ -15,7 +15,9 @@
 #include <linux/of_platform.h>
 #include <linux/dma-mapping.h>
 #include <linux/property.h>
+#include <linux/msi.h>
 #include <linux/cdx/cdx_bus.h>
+#include "cdx.h"
 
 #include "cdx.h"
 
@@ -47,6 +49,8 @@ static int cdx_populate_one(struct platform_device *pdev_parent,
 
 	dev_data.bus_id = dev_params->bus_id;
 	dev_data.func_id = dev_params->func_id;
+	dev_data.dev_id = dev_params->msi_device_id;
+	dev_data.num_msi = dev_params->num_msi;
 
 	memset(&pdevinfo, 0, sizeof(pdevinfo));
 	pdevinfo.fwnode = swnode;
@@ -76,6 +80,10 @@ static int cdx_populate_one(struct platform_device *pdev_parent,
 		goto out;
 	}
 
+	/* Set the MSI domain */
+	dev_set_msi_domain(&new_pdev->dev,
+			   irq_find_host(pdev_parent->dev.of_node));
+
 	return 0;
 
 out:
@@ -109,8 +117,22 @@ static int cdx_bus_device_discovery(struct platform_device *pdev)
 	int num_cdx_bus = 0, num_cdx_func = 0;
 	int bus_id = 0, func_id = 0;
 	struct device_node *np = pdev->dev.of_node;
+	struct irq_domain *cdx_msi_domain;
 	int ret;
 
+	/* If CDX MSI domain is not created, create one. */
+	cdx_msi_domain = irq_find_host(pdev->dev.of_node);
+	if (!cdx_msi_domain) {
+		np = pdev->dev.of_node;
+
+		ret = cdx_msi_domain_init(&pdev->dev, np->full_name);
+		if (ret != 0) {
+			dev_err(&pdev->dev,
+				"cdx_msi_domain_init() failed: %d", ret);
+			return ret;
+		}
+	}
+
 	/* TODO: Get number of busses from firmware */
 	num_cdx_bus = 1;
 
@@ -144,7 +166,16 @@ static int cdx_bus_device_discovery(struct platform_device *pdev)
 					ret);
 				goto fail;
 			}
+			ret = of_map_id(np, req_id, "msi-map", "msi-map-mask",
+					NULL, &dev_params.msi_device_id);
+			if (ret != 0) {
+				dev_err(&pdev->dev,
+					"of_map_id failed for MSI: %d\n",
+					ret);
+				goto fail;
+			}
 
+			dev_params.num_msi = 2;
 			dev_params.dev_type_idx = 0;
 			dev_params.res_cnt = 1;
 
diff --git a/drivers/bus/cdx/cdx.h b/drivers/bus/cdx/cdx.h
index 7db8b06de9cd..da2c282d4d93 100644
--- a/drivers/bus/cdx/cdx.h
+++ b/drivers/bus/cdx/cdx.h
@@ -19,6 +19,8 @@ struct cdx_dev_params_t {
 	struct resource res[CDX_DEV_NUM_RESOURCES];
 	int res_cnt;
 	u32 stream_id;
+	u32 msi_device_id;
+	u32 num_msi;
 };
 
 /**
@@ -26,10 +28,24 @@ struct cdx_dev_params_t {
  *	CDX device.
  * @bus_id: Bus ID for reset
  * @func_id: Function ID for reset
+ * @dev_id: Device ID for MSI.
+ * @num_msi: Number of MSI supported by the device
  */
 struct cdx_device_data {
 	u32 bus_id;
 	u32 func_id;
+	u32 dev_id;
+	u32 num_msi;
 };
 
+/**
+ * cdx_msi_domain_init - Init the CDX bus MSI domain.
+ * @cbus_dev: Device of the CDX bus
+ * @name: Name to be assigned to the newly created domain
+ *
+ * Return 0 on success, <0 on failure
+ */
+int cdx_msi_domain_init(struct device *cdev_bus,
+			 const char *name);
+
 #endif /* _CDX_H_ */
diff --git a/drivers/bus/cdx/cdx_msi_domain.c b/drivers/bus/cdx/cdx_msi_domain.c
new file mode 100644
index 000000000000..44472ae02d1c
--- /dev/null
+++ b/drivers/bus/cdx/cdx_msi_domain.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CDX bus driver MSI support
+ *
+ * Copyright(c) 2022 Xilinx.
+ *
+ */
+
+#include <linux/irq.h>
+#include <linux/msi.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+
+#include "cdx.h"
+
+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
+};
+
+static int cdx_msi_prepare(struct irq_domain *msi_domain,
+		struct device *dev,
+		int nvec, msi_alloc_info_t *info)
+{
+	struct msi_domain_info *msi_info;
+	struct cdx_device_data *dev_data;
+	u32 dev_id;
+
+	/* Retrieve device ID from platform data */
+	dev_data = dev->platform_data;
+	dev_id = dev_data->dev_id;
+
+	/* 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);
+
+	/* Allocate at least 32 MSIs, and always as a power of 2 */
+	nvec = max_t(int, 32, roundup_pow_of_two(nvec));
+	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,
+};
+
+static struct msi_domain_info cdx_msi_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
+	.ops	= &cdx_msi_ops,
+	.chip	= &cdx_msi_irq_chip,
+};
+
+int cdx_msi_domain_init(struct device *cbus_dev,
+		const char *name)
+{
+	struct irq_domain *parent;
+	struct irq_domain *cdx_msi_domain;
+	struct fwnode_handle *fwnode_handle;
+	struct device_node *parent_node;
+	struct device_node *np;
+
+	np = cbus_dev->of_node;
+	parent_node = of_parse_phandle(np, "msi-map", 1);
+
+	parent = irq_find_matching_fwnode(of_node_to_fwnode(parent_node),
+			DOMAIN_BUS_NEXUS);
+	if (!parent || !msi_get_domain_info(parent)) {
+		dev_err(cbus_dev, "%s: unable to locate ITS domain\n", name);
+		return -ENODEV;
+	}
+
+	fwnode_handle = of_node_to_fwnode(np);
+	cdx_msi_domain = platform_msi_create_irq_domain(fwnode_handle,
+						&cdx_msi_domain_info,
+						parent);
+	if (!cdx_msi_domain) {
+		dev_err(cbus_dev, "%s: unable to create cdx bus domain\n",
+			name);
+		return -1;
+	}
+
+	dev_info(cbus_dev, "cdx bus MSI: %s domain created\n", name);
+
+	return 0;
+}
-- 
2.25.1