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authorLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 18:53:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 18:53:03 -0700
commit316b7eaa932d99e6421bee9a89e4f19aefddd88a (patch)
tree1af5c2b727c58f4a8d5510e533835fd1a4102831 /Documentation/driver-api
parent4dee060625e1095c7065fead542e96ba9504c7eb (diff)
parentf281d010b87454e72475b668ad66e34961f744e0 (diff)
Merge tag 'for-linus-5.16-1' of https://github.com/cminyard/linux-ipmi
Pull IPMI driver updates from Corey Minyard: "A new type of low-level IPMI driver is added for direct communication over the IPMI message bus without a BMC between the driver and the bus. Other than that, lots of little bug fixes and enhancements" * tag 'for-linus-5.16-1' of https://github.com/cminyard/linux-ipmi: ipmi: kcs_bmc: Fix a memory leak in the error handling path of 'kcs_bmc_serio_add_device()' char: ipmi: replace snprintf in show functions with sysfs_emit ipmi: ipmb: fix dependencies to eliminate build error ipmi:ipmb: Add OF support ipmi: bt: Add ast2600 compatible string ipmi: bt-bmc: Use registers directly ipmi: ipmb: Fix off-by-one size check on rcvlen ipmi:ssif: Use depends on, not select, for I2C ipmi: Add docs for the IPMI IPMB driver ipmi: Add docs for IPMB direct addressing ipmi:ipmb: Add initial support for IPMI over IPMB ipmi: Add support for IPMB direct messages ipmi: Export ipmb_checksum() ipmi: Fix a typo ipmi: Check error code before processing BMC response ipmi:devintf: Return a proper error when recv buffer too small ipmi: Disable some operations during a panic ipmi:watchdog: Set panic count to proper value on a panic
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/ipmi.rst64
1 files changed, 62 insertions, 2 deletions
diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst
index bc281f10ce4b..e224e47b6b09 100644
--- a/Documentation/driver-api/ipmi.rst
+++ b/Documentation/driver-api/ipmi.rst
@@ -166,8 +166,8 @@ and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking
straight to the BMC on the current card. The channel must be
IPMI_BMC_CHANNEL.
-Messages that are destined to go out on the IPMB bus use the
-IPMI_IPMB_ADDR_TYPE address type. The format is::
+Messages that are destined to go out on the IPMB bus going through the
+BMC use the IPMI_IPMB_ADDR_TYPE address type. The format is::
struct ipmi_ipmb_addr
{
@@ -181,6 +181,23 @@ The "channel" here is generally zero, but some devices support more
than one channel, it corresponds to the channel as defined in the IPMI
spec.
+There is also an IPMB direct address for a situation where the sender
+is directly on an IPMB bus and doesn't have to go through the BMC.
+You can send messages to a specific management controller (MC) on the
+IPMB using the IPMI_IPMB_DIRECT_ADDR_TYPE with the following format::
+
+ struct ipmi_ipmb_direct_addr
+ {
+ int addr_type;
+ short channel;
+ unsigned char slave_addr;
+ unsigned char rq_lun;
+ unsigned char rs_lun;
+ };
+
+The channel is always zero. You can also receive commands from other
+MCs that you have registered to handle and respond to them, so you can
+use this to implement a management controller on a bus..
Messages
--------
@@ -348,6 +365,10 @@ user may be registered for each netfn/cmd/channel, but different users
may register for different commands, or the same command if the
channel bitmasks do not overlap.
+To respond to a received command, set the response bit in the returned
+netfn, use the address from the received message, and use the same
+msgid that you got in the receive message.
+
From userland, equivalent IOCTLs are provided to do these functions.
@@ -570,6 +591,45 @@ web page.
The driver supports a hot add and remove of interfaces through the I2C
sysfs interface.
+The IPMI IPMB Driver
+--------------------
+
+This driver is for supporting a system that sits on an IPMB bus; it
+allows the interface to look like a normal IPMI interface. Sending
+system interface addressed messages to it will cause the message to go
+to the registered BMC on the system (default at IPMI address 0x20).
+
+It also allows you to directly address other MCs on the bus using the
+ipmb direct addressing. You can receive commands from other MCs on
+the bus and they will be handled through the normal received command
+mechanism described above.
+
+Parameters are::
+
+ ipmi_ipmb.bmcaddr=<address to use for system interface addresses messages>
+ ipmi_ipmb.retry_time_ms=<Time between retries on IPMB>
+ ipmi_ipmb.max_retries=<Number of times to retry a message>
+
+Loading the module will not result in the driver automatcially
+starting unless there is device tree information setting it up. If
+you want to instantiate one of these by hand, do::
+
+ echo ipmi-ipmb <addr> > /sys/class/i2c-dev/i2c-<n>/device/new_device
+
+Note that the address you give here is the I2C address, not the IPMI
+address. So if you want your MC address to be 0x60, you put 0x30
+here. See the I2C driver info for more details.
+
+Command bridging to other IPMB busses through this interface does not
+work. The receive message queue is not implemented, by design. There
+is only one receive message queue on a BMC, and that is meant for the
+host drivers, not something on the IPMB bus.
+
+A BMC may have multiple IPMB busses, which bus your device sits on
+depends on how the system is wired. You can fetch the channels with
+"ipmitool channel info <n>" where <n> is the channel, with the
+channels being 0-7 and try the IPMB channels.
+
Other Pieces
------------