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authorDavid Fries <David@Fries.net>2014-04-08 22:37:09 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-27 13:56:21 -0700
commit8a0427d192e6043834414210dd14cc1289daff18 (patch)
tree1e76812e3744b6946a815fb94f877cc31d11b302 /drivers/w1/w1_netlink.h
parent34470e0bfae223e3f22bd2bd6e0e1dac366c9290 (diff)
downloadlinux-sh-8a0427d192e6043834414210dd14cc1289daff18.tar.gz
w1: optional bundling of netlink kernel replies
Applications can submit a set of commands in one packet to the kernel, and in some cases it is required such as reading the temperature sensor results. This adds an option W1_CN_BUNDLE to the flags of cn_msg to request the kernel to reply in one packet for efficiency. The cn_msg flags now check for unknown flag values and return an error if one is seen. See "Proper handling of unknown flags in system calls" http://lwn.net/Articles/588444/ This corrects the ack values returned as per the protocol standard, namely the original ack for status messages and seq + 1 for all others such as the data returned from a read. Some of the common variable names have been standardized as follows. struct cn_msg *cn struct w1_netlink_msg *msg struct w1_netlink_cmd *cmd struct w1_master *dev When an argument and a function scope variable would collide, add req_ to the argument. Signed-off-by: David Fries <David@Fries.net> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/w1/w1_netlink.h')
-rw-r--r--drivers/w1/w1_netlink.h36
1 files changed, 36 insertions, 0 deletions
diff --git a/drivers/w1/w1_netlink.h b/drivers/w1/w1_netlink.h
index 1e9504e67650..c99a9ce05e62 100644
--- a/drivers/w1/w1_netlink.h
+++ b/drivers/w1/w1_netlink.h
@@ -28,6 +28,17 @@
#include "w1.h"
/**
+ * enum w1_cn_msg_flags - bitfield flags for struct cn_msg.flags
+ *
+ * @W1_CN_BUNDLE: Request bundling replies into fewer messagse. Be prepared
+ * to handle multiple struct cn_msg, struct w1_netlink_msg, and
+ * struct w1_netlink_cmd in one packet.
+ */
+enum w1_cn_msg_flags {
+ W1_CN_BUNDLE = 1,
+};
+
+/**
* enum w1_netlink_message_types - message type
*
* @W1_SLAVE_ADD: notification that a slave device was added
@@ -49,6 +60,19 @@ enum w1_netlink_message_types {
W1_LIST_MASTERS,
};
+/**
+ * struct w1_netlink_msg - holds w1 message type, id, and result
+ *
+ * @type: one of enum w1_netlink_message_types
+ * @status: kernel feedback for success 0 or errno failure value
+ * @len: length of data following w1_netlink_msg
+ * @id: union holding master bus id (msg.id) and slave device id (id[8]).
+ * @data: start address of any following data
+ *
+ * The base message structure for w1 messages over netlink.
+ * The netlink connector data sequence is, struct nlmsghdr, struct cn_msg,
+ * then one or more struct w1_netlink_msg (each with optional data).
+ */
struct w1_netlink_msg
{
__u8 type;
@@ -66,6 +90,7 @@ struct w1_netlink_msg
/**
* enum w1_commands - commands available for master or slave operations
+ *
* @W1_CMD_READ: read len bytes
* @W1_CMD_WRITE: write len bytes
* @W1_CMD_SEARCH: initiate a standard search, returns only the slave
@@ -93,6 +118,17 @@ enum w1_commands {
W1_CMD_MAX
};
+/**
+ * struct w1_netlink_cmd - holds the command and data
+ *
+ * @cmd: one of enum w1_commands
+ * @res: reserved
+ * @len: length of data following w1_netlink_cmd
+ * @data: start address of any following data
+ *
+ * One or more struct w1_netlink_cmd is placed starting at w1_netlink_msg.data
+ * each with optional data.
+ */
struct w1_netlink_cmd
{
__u8 cmd;