devlink: allow driver to pass flash component name for line card device

Leverage the existing devlink flash update mechanism and allow driver
to pass a custom "component name" string identifying the line card
device to flash.

Example:
$ devlink lc show pci/0000:01:00.0 lc 8
pci/0000:01:00.0:
  lc 8 state active type 16x100G
    supported_types:
       16x100G
    devices:
      device 0 flashable true component lc8_dev0
      device 1 flashable false
      device 2 flashable false
      device 3 flashable false
$ devlink dev flash pci/0000:01:00.0 file some_file.mfa2 component lc8_dev0

Signed-off-by: Jiri Pirko <jiri@nvidia.com>

include/net/devlink.h

@@ -1575,7 +1575,8 @@ devlink_linecard_create(struct devlink *devlink, unsigned int linecard_index,
 void devlink_linecard_destroy(struct devlink_linecard *linecard);
 struct devlink_linecard_device *
 devlink_linecard_device_create(struct devlink_linecard *linecard,
-			       unsigned int device_index, void *priv);
+			       unsigned int device_index,
+			       const char *flash_component, void *priv);
 void
 devlink_linecard_device_destroy(struct devlink_linecard *linecard,
 				struct devlink_linecard_device *linecard_device);

net/core/devlink.c

@@ -2064,6 +2064,7 @@ struct devlink_info_req {
 struct devlink_linecard_device {
 	struct list_head list;
 	unsigned int index;
+	const char *flash_component;
 	void *priv;
 };
 
@@ -2080,6 +2081,10 @@ devlink_nl_linecard_device_fill(struct sk_buff *msg,
 	if (nla_put_u32(msg, DEVLINK_ATTR_LINECARD_DEVICE_INDEX,
 			linecard_device->index))
 		return -EMSGSIZE;
+	if (linecard_device->flash_component &&
+	    nla_put_string(msg, DEVLINK_ATTR_FLASH_UPDATE_COMPONENT,
+			   linecard_device->flash_component))
+		return -EMSGSIZE;
 	nla_nest_end(msg, attr);
 
 	return 0;
@@ -10498,20 +10503,24 @@ EXPORT_SYMBOL_GPL(devlink_linecard_destroy);
  *
  *	@linecard: devlink linecard
  *	@device_index: index of the linecard device
+ *	@flash_component: name of flash update component,
+ *			  NULL if unable to flash
  *	@priv: user priv pointer
  *
  *	Return: Line card device structure or an ERR_PTR() encoded error code.
  */
 struct devlink_linecard_device *
 devlink_linecard_device_create(struct devlink_linecard *linecard,
-			       unsigned int device_index, void *priv)
+			       unsigned int device_index,
+			       const char *flash_component, void *priv)
 {
 	struct devlink_linecard_device *linecard_device;
 
 	linecard_device = kzalloc(sizeof(*linecard_device), GFP_KERNEL);
 	if (!linecard_device)
 		return ERR_PTR(-ENOMEM);
 	linecard_device->index = device_index;
+	linecard_device->flash_component = flash_component;
 	linecard_device->priv = priv;
 	mutex_lock(&linecard->devlink->lock);
 	list_add_tail(&linecard_device->list, &linecard->device_list);