cdx: Create resource debugfs file for cdx device

resource debugfs file contains host addresses of CDX device resources.
Each line of the resource file describe type of resource, a region
with start-end and flag fields.
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://lore.kernel.org/r/20231222064627.2828960-2-abhijit.gangurde@amd.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/cdx/cdx.c

@@ -67,6 +67,7 @@
 #include <linux/cdx/cdx_bus.h>
 #include <linux/iommu.h>
 #include <linux/dma-map-ops.h>
+#include <linux/debugfs.h>
 #include "cdx.h"
 
 /* Default DMA mask for devices on a CDX bus */
@@ -77,6 +78,8 @@
 static DEFINE_IDA(cdx_controller_ida);
 /* Lock to protect controller ops */
 static DEFINE_MUTEX(cdx_controller_lock);
+/* Debugfs dir for cdx bus */
+static struct dentry *cdx_debugfs_dir;
 
 static char *compat_node_name = "xlnx,versal-net-cdx";
 
@@ -151,6 +154,7 @@ static int cdx_unregister_device(struct device *dev,
 			cdx->ops->bus_disable(cdx, cdx_dev->bus_num);
 	} else {
 		cdx_destroy_res_attr(cdx_dev, MAX_CDX_DEV_RESOURCES);
+		debugfs_remove_recursive(cdx_dev->debugfs_dir);
 		kfree(cdx_dev->driver_override);
 		cdx_dev->driver_override = NULL;
 	}
@@ -554,6 +558,31 @@ static const struct attribute_group *cdx_dev_groups[] = {
 	NULL,
 };
 
+static int cdx_debug_resource_show(struct seq_file *s, void *data)
+{
+	struct cdx_device *cdx_dev = s->private;
+	int i;
+
+	for (i = 0; i < MAX_CDX_DEV_RESOURCES; i++) {
+		struct resource *res =  &cdx_dev->res[i];
+
+		seq_printf(s, "%pr\n", res);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(cdx_debug_resource);
+
+static void cdx_device_debugfs_init(struct cdx_device *cdx_dev)
+{
+	cdx_dev->debugfs_dir = debugfs_create_dir(dev_name(&cdx_dev->dev), cdx_debugfs_dir);
+	if (IS_ERR(cdx_dev->debugfs_dir))
+		return;
+
+	debugfs_create_file("resource", 0444, cdx_dev->debugfs_dir, cdx_dev,
+			    &cdx_debug_resource_fops);
+}
+
 static ssize_t rescan_store(const struct bus_type *bus,
 			    const char *buf, size_t count)
 {
@@ -803,6 +832,8 @@ int cdx_device_add(struct cdx_dev_params *dev_params)
 		}
 	}
 
+	cdx_device_debugfs_init(cdx_dev);
+
 	return 0;
 resource_create_fail:
 	cdx_destroy_res_attr(cdx_dev, i);
@@ -907,6 +938,12 @@ EXPORT_SYMBOL_NS_GPL(cdx_unregister_controller, CDX_BUS_CONTROLLER);
 
 static int __init cdx_bus_init(void)
 {
-	return bus_register(&cdx_bus_type);
+	int ret;
+
+	ret = bus_register(&cdx_bus_type);
+	if (!ret)
+		cdx_debugfs_dir = debugfs_create_dir(cdx_bus_type.name, NULL);
+
+	return ret;
 }
 postcore_initcall(cdx_bus_init);

include/linux/cdx/cdx_bus.h

@@ -113,6 +113,7 @@ struct cdx_controller {
  * @dev_num: Device number for this device
  * @res: array of MMIO region entries
  * @res_attr: resource binary attribute
+ * @debugfs_dir: debugfs directory for this device
  * @res_count: number of valid MMIO regions
  * @dma_mask: Default DMA mask
  * @flags: CDX device flags
@@ -136,6 +137,7 @@ struct cdx_device {
 	u8 dev_num;
 	struct resource res[MAX_CDX_DEV_RESOURCES];
 	struct bin_attribute *res_attr[MAX_CDX_DEV_RESOURCES];
+	struct dentry *debugfs_dir;
 	u8 res_count;
 	u64 dma_mask;
 	u16 flags;