cdx: create sysfs bin files for cdx resources

Resource binary file contains the content of the memory regions.
These resources<x> devices can be used to mmap the MMIO regions in
the user-space.

Co-developed-by: Puneet Gupta <puneet.gupta@amd.com>
Signed-off-by: Puneet Gupta <puneet.gupta@amd.com>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://lore.kernel.org/r/20231222064627.2828960-1-abhijit.gangurde@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: abhijitG-xlnx

Documentation/ABI/testing/sysfs-bus-cdx

@@ -98,6 +98,13 @@ Description:
 
 		  # echo 1 > /sys/bus/cdx/devices/.../remove
 
+What:		/sys/bus/cdx/devices/.../resource<N>
+Date:		July 2023
+Contact:	puneet.gupta@amd.com
+Description:
+		The resource binary file contains the content of the memory
+		regions. These files can be m'maped from userspace.
+
 What:		/sys/bus/cdx/devices/.../modalias
 Date:		July 2023
 Contact:	nipun.gupta@amd.com

drivers/cdx/cdx.c

@@ -80,6 +80,8 @@ static DEFINE_MUTEX(cdx_controller_lock);
 
 static char *compat_node_name = "xlnx,versal-net-cdx";
 
+static void cdx_destroy_res_attr(struct cdx_device *cdx_dev, int num);
+
 /**
  * cdx_dev_reset - Reset a CDX device
  * @dev: CDX device
@@ -148,6 +150,7 @@ static int cdx_unregister_device(struct device *dev,
 		if (cdx_dev->enabled && cdx->ops->bus_disable)
 			cdx->ops->bus_disable(cdx, cdx_dev->bus_num);
 	} else {
+		cdx_destroy_res_attr(cdx_dev, MAX_CDX_DEV_RESOURCES);
 		kfree(cdx_dev->driver_override);
 		cdx_dev->driver_override = NULL;
 	}
@@ -643,11 +646,105 @@ static void cdx_device_release(struct device *dev)
 	kfree(cdx_dev);
 }
 
+static const struct vm_operations_struct cdx_phys_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+	.access = generic_access_phys,
+#endif
+};
+
+/**
+ * cdx_mmap_resource - map a CDX resource into user memory space
+ * @fp: File pointer. Not used in this function, but required where
+ *      this API is registered as a callback.
+ * @kobj: kobject for mapping
+ * @attr: struct bin_attribute for the file being mapped
+ * @vma: struct vm_area_struct passed into the mmap
+ *
+ * Use the regular CDX mapping routines to map a CDX resource into userspace.
+ *
+ * Return: true on success, false otherwise.
+ */
+static int cdx_mmap_resource(struct file *fp, struct kobject *kobj,
+			     struct bin_attribute *attr,
+			     struct vm_area_struct *vma)
+{
+	struct cdx_device *cdx_dev = to_cdx_device(kobj_to_dev(kobj));
+	int num = (unsigned long)attr->private;
+	struct resource *res;
+	unsigned long size;
+
+	res = &cdx_dev->res[num];
+	if (iomem_is_exclusive(res->start))
+		return -EINVAL;
+
+	/* Make sure the caller is mapping a valid resource for this device */
+	size = ((cdx_resource_len(cdx_dev, num) - 1) >> PAGE_SHIFT) + 1;
+	if (vma->vm_pgoff + vma_pages(vma) > size)
+		return -EINVAL;
+
+	/*
+	 * Map memory region and vm->vm_pgoff is expected to be an
+	 * offset within that region.
+	 */
+	vma->vm_page_prot = pgprot_device(vma->vm_page_prot);
+	vma->vm_pgoff += (cdx_resource_start(cdx_dev, num) >> PAGE_SHIFT);
+	vma->vm_ops = &cdx_phys_vm_ops;
+	return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+				  vma->vm_end - vma->vm_start,
+				  vma->vm_page_prot);
+}
+
+static void cdx_destroy_res_attr(struct cdx_device *cdx_dev, int num)
+{
+	int i;
+
+	/* removing the bin attributes */
+	for (i = 0; i < num; i++) {
+		struct bin_attribute *res_attr;
+
+		res_attr = cdx_dev->res_attr[i];
+		if (res_attr) {
+			sysfs_remove_bin_file(&cdx_dev->dev.kobj, res_attr);
+			kfree(res_attr);
+		}
+	}
+}
+
+#define CDX_RES_ATTR_NAME_LEN	10
+static int cdx_create_res_attr(struct cdx_device *cdx_dev, int num)
+{
+	struct bin_attribute *res_attr;
+	char *res_attr_name;
+	int ret;
+
+	res_attr = kzalloc(sizeof(*res_attr) + CDX_RES_ATTR_NAME_LEN, GFP_ATOMIC);
+	if (!res_attr)
+		return -ENOMEM;
+
+	res_attr_name = (char *)(res_attr + 1);
+
+	sysfs_bin_attr_init(res_attr);
+
+	cdx_dev->res_attr[num] = res_attr;
+	sprintf(res_attr_name, "resource%d", num);
+
+	res_attr->mmap = cdx_mmap_resource;
+	res_attr->attr.name = res_attr_name;
+	res_attr->attr.mode = 0600;
+	res_attr->size = cdx_resource_len(cdx_dev, num);
+	res_attr->private = (void *)(unsigned long)num;
+	ret = sysfs_create_bin_file(&cdx_dev->dev.kobj, res_attr);
+	if (ret)
+		kfree(res_attr);
+
+	return ret;
+}
+
 int cdx_device_add(struct cdx_dev_params *dev_params)
 {
 	struct cdx_controller *cdx = dev_params->cdx;
 	struct cdx_device *cdx_dev;
-	int ret;
+	int ret, i;
 
 	cdx_dev = kzalloc(sizeof(*cdx_dev), GFP_KERNEL);
 	if (!cdx_dev)
@@ -690,7 +787,26 @@ int cdx_device_add(struct cdx_dev_params *dev_params)
 		goto fail;
 	}
 
+	/* Create resource<N> attributes */
+	for (i = 0; i < MAX_CDX_DEV_RESOURCES; i++) {
+		if (cdx_resource_flags(cdx_dev, i) & IORESOURCE_MEM) {
+			/* skip empty resources */
+			if (!cdx_resource_len(cdx_dev, i))
+				continue;
+
+			ret = cdx_create_res_attr(cdx_dev, i);
+			if (ret != 0) {
+				dev_err(&cdx_dev->dev,
+					"cdx device resource<%d> file creation failed: %d", i, ret);
+				goto resource_create_fail;
+			}
+		}
+	}
+
 	return 0;
+resource_create_fail:
+	cdx_destroy_res_attr(cdx_dev, i);
+	device_del(&cdx_dev->dev);
 fail:
 	/*
 	 * Do not free cdx_dev here as it would be freed in

include/linux/cdx/cdx_bus.h

@@ -135,6 +135,7 @@ struct cdx_device {
 	u8 bus_num;
 	u8 dev_num;
 	struct resource res[MAX_CDX_DEV_RESOURCES];
+	struct bin_attribute *res_attr[MAX_CDX_DEV_RESOURCES];
 	u8 res_count;
 	u64 dma_mask;
 	u16 flags;
@@ -147,6 +148,15 @@ struct cdx_device {
 #define to_cdx_device(_dev) \
 	container_of(_dev, struct cdx_device, dev)
 
+#define cdx_resource_start(dev, num)	((dev)->res[(num)].start)
+#define cdx_resource_end(dev, num)	((dev)->res[(num)].end)
+#define cdx_resource_flags(dev, num)	((dev)->res[(num)].flags)
+#define cdx_resource_len(dev, num) \
+	((cdx_resource_start((dev), (num)) == 0 &&	\
+	  cdx_resource_end((dev), (num)) ==		\
+	  cdx_resource_start((dev), (num))) ? 0 :	\
+	 (cdx_resource_end((dev), (num)) -		\
+	  cdx_resource_start((dev), (num)) + 1))
 /**
  * struct cdx_driver - CDX device driver
  * @driver: Generic device driver