[PATCH 3/4] cdx: create sysfs resource files

[Abhijit Gangurde]

Resource files provides the basic MMIO regions info to the
user-space. Also, resources<x> devices can be used to mmap the
MMIO regions in the user-space.

Co-developed-by: Puneet Gupta <puneet.gupta@xxxxxxx>
Signed-off-by: Puneet Gupta <puneet.gupta@xxxxxxx>
Co-developed-by: Nipun Gupta <nipun.gupta@xxxxxxx>
Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@xxxxxxx>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@xxxxxxx>
Tested-by: Nikhil Agarwal <nikhil.agarwal@xxxxxxx>
---
 Documentation/ABI/testing/sysfs-bus-cdx |  15 +++
 drivers/cdx/cdx.c                       | 139 +++++++++++++++++++++++-
 include/linux/cdx/cdx_bus.h             |  10 ++
 3 files changed, 163 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cdx b/Documentation/ABI/testing/sysfs-bus-cdx
index d9e00058471d..6ca47b6442ce 100644
--- a/Documentation/ABI/testing/sysfs-bus-cdx
+++ b/Documentation/ABI/testing/sysfs-bus-cdx
@@ -76,3 +76,18 @@ Description:
 		For example::
 
 		  # echo 1 > /sys/bus/cdx/devices/.../remove
+
+What:		/sys/bus/cdx/devices/.../resource
+Date:		July 2023
+Contact:	puneet.gupta@xxxxxxx
+Description:
+		The resource file contains host addresses of CDX device
+		resources. Each line of the resource file describes a region
+		with start, end, and flag fields.
+
+What:		/sys/bus/cdx/devices/.../resource<N>
+Date:		July 2023
+Contact:	puneet.gupta@xxxxxxx
+Description:
+		The resource binary file contains the content of the memory
+		regions. These files can be m'maped from userspace.
diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index 4d20047b55bb..9d568df8e566 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -73,6 +73,8 @@
 /* CDX controllers registered with the CDX bus */
 static DEFINE_XARRAY_ALLOC(cdx_controllers);
 
+static void cdx_destroy_res_attr(struct cdx_device *cdx_dev, int num);
+
 /**
  * cdx_dev_reset - Reset a CDX device
  * @dev: CDX device
@@ -126,6 +128,8 @@ static int cdx_unregister_device(struct device *dev,
 {
 	struct cdx_device *cdx_dev = to_cdx_device(dev);
 
+	cdx_destroy_res_attr(cdx_dev, MAX_CDX_DEV_RESOURCES);
+
 	kfree(cdx_dev->driver_override);
 	cdx_dev->driver_override = NULL;
 	/*
@@ -375,12 +379,32 @@ static ssize_t driver_override_show(struct device *dev,
 }
 static DEVICE_ATTR_RW(driver_override);
 
+static ssize_t resource_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct cdx_device *cdx_dev = to_cdx_device(dev);
+	size_t len = 0;
+	int i;
+
+	for (i = 0; i < MAX_CDX_DEV_RESOURCES; i++) {
+		struct resource *res =  &cdx_dev->res[i];
+
+		len += sysfs_emit_at(buf, len, "0x%016llx 0x%016llx 0x%016llx\n",
+				    (unsigned long long)res->start,
+				    (unsigned long long)res->end,
+				    (unsigned long long)res->flags);
+	}
+
+	return len;
+}
+static DEVICE_ATTR_RO(resource);
+
 static struct attribute *cdx_dev_attrs[] = {
 	&dev_attr_remove.attr,
 	&dev_attr_reset.attr,
 	&dev_attr_vendor.attr,
 	&dev_attr_device.attr,
 	&dev_attr_driver_override.attr,
+	&dev_attr_resource.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(cdx_dev);
@@ -514,12 +538,106 @@ 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 device *parent = cdx->dev;
 	struct cdx_device *cdx_dev;
-	int ret;
+	int ret, i;
 
 	cdx_dev = kzalloc(sizeof(*cdx_dev), GFP_KERNEL);
 	if (!cdx_dev)
@@ -558,7 +676,26 @@ 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 fail1;
+			}
+		}
+	}
+
 	return 0;
+fail1:
+	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
diff --git a/include/linux/cdx/cdx_bus.h b/include/linux/cdx/cdx_bus.h
index 5da0634ae4ee..e93f1cd8ae33 100644
--- a/include/linux/cdx/cdx_bus.h
+++ b/include/linux/cdx/cdx_bus.h
@@ -104,6 +104,7 @@ 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;
@@ -114,6 +115,15 @@ 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
-- 
2.25.1