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@@ -5,69 +5,122 @@ Message types.
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=============
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There are three types of messages between w1 core and userspace:
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-1. Events. They are generated each time new master or slave device found
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- either due to automatic or requested search.
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-2. Userspace commands. Includes read/write and search/alarm search comamnds.
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+1. Events. They are generated each time new master or slave device
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+ found either due to automatic or requested search.
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+2. Userspace commands.
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3. Replies to userspace commands.
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Protocol.
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========
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-[struct cn_msg] - connector header. It's length field is equal to size of the attached data.
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+[struct cn_msg] - connector header.
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+ Its length field is equal to size of the attached data
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[struct w1_netlink_msg] - w1 netlink header.
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__u8 type - message type.
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- W1_SLAVE_ADD/W1_SLAVE_REMOVE - slave add/remove events.
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- W1_MASTER_ADD/W1_MASTER_REMOVE - master add/remove events.
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- W1_MASTER_CMD - userspace command for bus master device (search/alarm search).
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- W1_SLAVE_CMD - userspace command for slave device (read/write/ search/alarm search
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- for bus master device where given slave device found).
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+ W1_LIST_MASTERS
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+ list current bus masters
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+ W1_SLAVE_ADD/W1_SLAVE_REMOVE
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+ slave add/remove events
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+ W1_MASTER_ADD/W1_MASTER_REMOVE
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+ master add/remove events
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+ W1_MASTER_CMD
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+ userspace command for bus master
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+ device (search/alarm search)
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+ W1_SLAVE_CMD
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+ userspace command for slave device
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+ (read/write/touch)
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__u8 res - reserved
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- __u16 len - size of attached to this header data.
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+ __u16 len - size of data attached to this header data
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union {
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- __u8 id; - slave unique device id
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+ __u8 id[8]; - slave unique device id
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struct w1_mst {
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- __u32 id; - master's id.
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+ __u32 id; - master's id
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__u32 res; - reserved
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} mst;
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} id;
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-[strucrt w1_netlink_cmd] - command for gived master or slave device.
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+[struct w1_netlink_cmd] - command for given master or slave device.
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__u8 cmd - command opcode.
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- W1_CMD_READ - read command.
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- W1_CMD_WRITE - write command.
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- W1_CMD_SEARCH - search command.
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- W1_CMD_ALARM_SEARCH - alarm search command.
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+ W1_CMD_READ - read command
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+ W1_CMD_WRITE - write command
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+ W1_CMD_TOUCH - touch command
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+ (write and sample data back to userspace)
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+ W1_CMD_SEARCH - search command
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+ W1_CMD_ALARM_SEARCH - alarm search command
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__u8 res - reserved
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- __u16 len - length of data for this command.
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- For read command data must be allocated like for write command.
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- __u8 data[0] - data for this command.
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+ __u16 len - length of data for this command
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+ For read command data must be allocated like for write command
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+ __u8 data[0] - data for this command
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-Each connector message can include one or more w1_netlink_msg with zero of more attached w1_netlink_cmd messages.
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+Each connector message can include one or more w1_netlink_msg with
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+zero or more attached w1_netlink_cmd messages.
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-For event messages there are no w1_netlink_cmd embedded structures, only connector header
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-and w1_netlink_msg strucutre with "len" field being zero and filled type (one of event types)
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-and id - either 8 bytes of slave unique id in host order, or master's id, which is assigned
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-to bus master device when it is added to w1 core.
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+For event messages there are no w1_netlink_cmd embedded structures,
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+only connector header and w1_netlink_msg strucutre with "len" field
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+being zero and filled type (one of event types) and id:
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+either 8 bytes of slave unique id in host order,
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+or master's id, which is assigned to bus master device
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+when it is added to w1 core.
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+
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+Currently replies to userspace commands are only generated for read
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+command request. One reply is generated exactly for one w1_netlink_cmd
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+read request. Replies are not combined when sent - i.e. typical reply
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+messages looks like the following:
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-Currently replies to userspace commands are only generated for read command request.
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-One reply is generated exactly for one w1_netlink_cmd read request.
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-Replies are not combined when sent - i.e. typical reply messages looks like the following:
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[cn_msg][w1_netlink_msg][w1_netlink_cmd]
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-cn_msg.len = sizeof(struct w1_netlink_msg) + sizeof(struct w1_netlink_cmd) + cmd->len;
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+cn_msg.len = sizeof(struct w1_netlink_msg) +
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+ sizeof(struct w1_netlink_cmd) +
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+ cmd->len;
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w1_netlink_msg.len = sizeof(struct w1_netlink_cmd) + cmd->len;
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w1_netlink_cmd.len = cmd->len;
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+Replies to W1_LIST_MASTERS should send a message back to the userspace
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+which will contain list of all registered master ids in the following
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+format:
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+
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+ cn_msg (CN_W1_IDX.CN_W1_VAL as id, len is equal to sizeof(struct
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+ w1_netlink_msg) plus number of masters multipled by 4)
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+ w1_netlink_msg (type: W1_LIST_MASTERS, len is equal to
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+ number of masters multiplied by 4 (u32 size))
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+ id0 ... idN
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+
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+ Each message is at most 4k in size, so if number of master devices
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+ exceeds this, it will be split into several messages,
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+ cn.seq will be increased for each one.
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+
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+W1 search and alarm search commands.
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+request:
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+[cn_msg]
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+ [w1_netlink_msg type = W1_MASTER_CMD
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+ id is equal to the bus master id to use for searching]
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+ [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH]
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+
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+reply:
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+ [cn_msg, ack = 1 and increasing, 0 means the last message,
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+ seq is equal to the request seq]
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+ [w1_netlink_msg type = W1_MASTER_CMD]
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+ [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH
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+ len is equal to number of IDs multiplied by 8]
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+ [64bit-id0 ... 64bit-idN]
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+Length in each header corresponds to the size of the data behind it, so
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+w1_netlink_cmd->len = N * 8; where N is number of IDs in this message.
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+ Can be zero.
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+w1_netlink_msg->len = sizeof(struct w1_netlink_cmd) + N * 8;
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+cn_msg->len = sizeof(struct w1_netlink_msg) +
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+ sizeof(struct w1_netlink_cmd) +
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+ N*8;
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Operation steps in w1 core when new command is received.
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=======================================================
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-When new message (w1_netlink_msg) is received w1 core detects if it is master of slave request,
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-according to w1_netlink_msg.type field.
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+When new message (w1_netlink_msg) is received w1 core detects if it is
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+master or slave request, according to w1_netlink_msg.type field.
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Then master or slave device is searched for.
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-When found, master device (requested or those one on where slave device is found) is locked.
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-If slave command is requested, then reset/select procedure is started to select given device.
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+When found, master device (requested or those one on where slave device
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+is found) is locked. If slave command is requested, then reset/select
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+procedure is started to select given device.
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Then all requested in w1_netlink_msg operations are performed one by one.
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If command requires reply (like read command) it is sent on command completion.
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@@ -82,8 +135,8 @@ Connector [1] specific documentation.
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Each connector message includes two u32 fields as "address".
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w1 uses CN_W1_IDX and CN_W1_VAL defined in include/linux/connector.h header.
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Each message also includes sequence and acknowledge numbers.
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-Sequence number for event messages is appropriate bus master sequence number increased with
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-each event message sent "through" this master.
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+Sequence number for event messages is appropriate bus master sequence number
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+increased with each event message sent "through" this master.
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Sequence number for userspace requests is set by userspace application.
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Sequence number for reply is the same as was in request, and
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acknowledge number is set to seq+1.
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@@ -93,6 +146,6 @@ Additional documantion, source code examples.
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============================================
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1. Documentation/connector
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-2. http://tservice.net.ru/~s0mbre/archive/w1
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-This archive includes userspace application w1d.c which
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-uses read/write/search commands for all master/slave devices found on the bus.
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+2. http://www.ioremap.net/archive/w1
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+This archive includes userspace application w1d.c which uses
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+read/write/search commands for all master/slave devices found on the bus.
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