mirror of
https://github.com/adulau/aha.git
synced 2024-12-28 11:46:19 +00:00
w1: documentation update
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Evgeniy Polyakov
Linus Torvalds
parent
3b8384070e
commit
e4e056aa35
1 changed files with 91 additions and 38 deletions
|
|
@ -5,69 +5,122 @@ Message types.
|
|||
=============
|
||||
|
||||
There are three types of messages between w1 core and userspace:
|
||||
1. Events. They are generated each time new master or slave device found
|
||||
either due to automatic or requested search.
|
||||
2. Userspace commands. Includes read/write and search/alarm search comamnds.
|
||||
1. Events. They are generated each time new master or slave device
|
||||
found either due to automatic or requested search.
|
||||
2. Userspace commands.
|
||||
3. Replies to userspace commands.
|
||||
|
||||
|
||||
Protocol.
|
||||
========
|
||||
|
||||
[struct cn_msg] - connector header. It's length field is equal to size of the attached data.
|
||||
[struct cn_msg] - connector header.
|
||||
Its length field is equal to size of the attached data
|
||||
[struct w1_netlink_msg] - w1 netlink header.
|
||||
__u8 type - message type.
|
||||
W1_SLAVE_ADD/W1_SLAVE_REMOVE - slave add/remove events.
|
||||
W1_MASTER_ADD/W1_MASTER_REMOVE - master add/remove events.
|
||||
W1_MASTER_CMD - userspace command for bus master device (search/alarm search).
|
||||
W1_SLAVE_CMD - userspace command for slave device (read/write/ search/alarm search
|
||||
for bus master device where given slave device found).
|
||||
W1_LIST_MASTERS
|
||||
list current bus masters
|
||||
W1_SLAVE_ADD/W1_SLAVE_REMOVE
|
||||
slave add/remove events
|
||||
W1_MASTER_ADD/W1_MASTER_REMOVE
|
||||
master add/remove events
|
||||
W1_MASTER_CMD
|
||||
userspace command for bus master
|
||||
device (search/alarm search)
|
||||
W1_SLAVE_CMD
|
||||
userspace command for slave device
|
||||
(read/write/touch)
|
||||
__u8 res - reserved
|
||||
__u16 len - size of attached to this header data.
|
||||
__u16 len - size of data attached to this header data
|
||||
union {
|
||||
__u8 id; - slave unique device id
|
||||
__u8 id[8]; - slave unique device id
|
||||
struct w1_mst {
|
||||
__u32 id; - master's id.
|
||||
__u32 id; - master's id
|
||||
__u32 res; - reserved
|
||||
} mst;
|
||||
} id;
|
||||
|
||||
[strucrt w1_netlink_cmd] - command for gived master or slave device.
|
||||
[struct w1_netlink_cmd] - command for given master or slave device.
|
||||
__u8 cmd - command opcode.
|
||||
W1_CMD_READ - read command.
|
||||
W1_CMD_WRITE - write command.
|
||||
W1_CMD_SEARCH - search command.
|
||||
W1_CMD_ALARM_SEARCH - alarm search command.
|
||||
W1_CMD_READ - read command
|
||||
W1_CMD_WRITE - write command
|
||||
W1_CMD_TOUCH - touch command
|
||||
(write and sample data back to userspace)
|
||||
W1_CMD_SEARCH - search command
|
||||
W1_CMD_ALARM_SEARCH - alarm search command
|
||||
__u8 res - reserved
|
||||
__u16 len - length of data for this command.
|
||||
For read command data must be allocated like for write command.
|
||||
__u8 data[0] - data for this command.
|
||||
__u16 len - length of data for this command
|
||||
For read command data must be allocated like for write command
|
||||
__u8 data[0] - data for this command
|
||||
|
||||
|
||||
Each connector message can include one or more w1_netlink_msg with zero of more attached w1_netlink_cmd messages.
|
||||
Each connector message can include one or more w1_netlink_msg with
|
||||
zero or more attached w1_netlink_cmd messages.
|
||||
|
||||
For event messages there are no w1_netlink_cmd embedded structures, only connector header
|
||||
and w1_netlink_msg strucutre with "len" field being zero and filled type (one of event types)
|
||||
and id - either 8 bytes of slave unique id in host order, or master's id, which is assigned
|
||||
to bus master device when it is added to w1 core.
|
||||
For event messages there are no w1_netlink_cmd embedded structures,
|
||||
only connector header and w1_netlink_msg strucutre with "len" field
|
||||
being zero and filled type (one of event types) and id:
|
||||
either 8 bytes of slave unique id in host order,
|
||||
or master's id, which is assigned to bus master device
|
||||
when it is added to w1 core.
|
||||
|
||||
Currently replies to userspace commands are only generated for read
|
||||
command request. One reply is generated exactly for one w1_netlink_cmd
|
||||
read request. Replies are not combined when sent - i.e. typical reply
|
||||
messages looks like the following:
|
||||
|
||||
Currently replies to userspace commands are only generated for read command request.
|
||||
One reply is generated exactly for one w1_netlink_cmd read request.
|
||||
Replies are not combined when sent - i.e. typical reply messages looks like the following:
|
||||
[cn_msg][w1_netlink_msg][w1_netlink_cmd]
|
||||
cn_msg.len = sizeof(struct w1_netlink_msg) + sizeof(struct w1_netlink_cmd) + cmd->len;
|
||||
cn_msg.len = sizeof(struct w1_netlink_msg) +
|
||||
sizeof(struct w1_netlink_cmd) +
|
||||
cmd->len;
|
||||
w1_netlink_msg.len = sizeof(struct w1_netlink_cmd) + cmd->len;
|
||||
w1_netlink_cmd.len = cmd->len;
|
||||
|
||||
Replies to W1_LIST_MASTERS should send a message back to the userspace
|
||||
which will contain list of all registered master ids in the following
|
||||
format:
|
||||
|
||||
cn_msg (CN_W1_IDX.CN_W1_VAL as id, len is equal to sizeof(struct
|
||||
w1_netlink_msg) plus number of masters multipled by 4)
|
||||
w1_netlink_msg (type: W1_LIST_MASTERS, len is equal to
|
||||
number of masters multiplied by 4 (u32 size))
|
||||
id0 ... idN
|
||||
|
||||
Each message is at most 4k in size, so if number of master devices
|
||||
exceeds this, it will be split into several messages,
|
||||
cn.seq will be increased for each one.
|
||||
|
||||
W1 search and alarm search commands.
|
||||
request:
|
||||
[cn_msg]
|
||||
[w1_netlink_msg type = W1_MASTER_CMD
|
||||
id is equal to the bus master id to use for searching]
|
||||
[w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH]
|
||||
|
||||
reply:
|
||||
[cn_msg, ack = 1 and increasing, 0 means the last message,
|
||||
seq is equal to the request seq]
|
||||
[w1_netlink_msg type = W1_MASTER_CMD]
|
||||
[w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH
|
||||
len is equal to number of IDs multiplied by 8]
|
||||
[64bit-id0 ... 64bit-idN]
|
||||
Length in each header corresponds to the size of the data behind it, so
|
||||
w1_netlink_cmd->len = N * 8; where N is number of IDs in this message.
|
||||
Can be zero.
|
||||
w1_netlink_msg->len = sizeof(struct w1_netlink_cmd) + N * 8;
|
||||
cn_msg->len = sizeof(struct w1_netlink_msg) +
|
||||
sizeof(struct w1_netlink_cmd) +
|
||||
N*8;
|
||||
|
||||
Operation steps in w1 core when new command is received.
|
||||
=======================================================
|
||||
|
||||
When new message (w1_netlink_msg) is received w1 core detects if it is master of slave request,
|
||||
according to w1_netlink_msg.type field.
|
||||
When new message (w1_netlink_msg) is received w1 core detects if it is
|
||||
master or slave request, according to w1_netlink_msg.type field.
|
||||
Then master or slave device is searched for.
|
||||
When found, master device (requested or those one on where slave device is found) is locked.
|
||||
If slave command is requested, then reset/select procedure is started to select given device.
|
||||
When found, master device (requested or those one on where slave device
|
||||
is found) is locked. If slave command is requested, then reset/select
|
||||
procedure is started to select given device.
|
||||
|
||||
Then all requested in w1_netlink_msg operations are performed one by one.
|
||||
If command requires reply (like read command) it is sent on command completion.
|
||||
|
|
@ -82,8 +135,8 @@ Connector [1] specific documentation.
|
|||
Each connector message includes two u32 fields as "address".
|
||||
w1 uses CN_W1_IDX and CN_W1_VAL defined in include/linux/connector.h header.
|
||||
Each message also includes sequence and acknowledge numbers.
|
||||
Sequence number for event messages is appropriate bus master sequence number increased with
|
||||
each event message sent "through" this master.
|
||||
Sequence number for event messages is appropriate bus master sequence number
|
||||
increased with each event message sent "through" this master.
|
||||
Sequence number for userspace requests is set by userspace application.
|
||||
Sequence number for reply is the same as was in request, and
|
||||
acknowledge number is set to seq+1.
|
||||
|
|
@ -93,6 +146,6 @@ Additional documantion, source code examples.
|
|||
============================================
|
||||
|
||||
1. Documentation/connector
|
||||
2. http://tservice.net.ru/~s0mbre/archive/w1
|
||||
This archive includes userspace application w1d.c which
|
||||
uses read/write/search commands for all master/slave devices found on the bus.
|
||||
2. http://www.ioremap.net/archive/w1
|
||||
This archive includes userspace application w1d.c which uses
|
||||
read/write/search commands for all master/slave devices found on the bus.
|
||||
|
|
|
|||
Loading…
Reference in a new issue