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ac499fba98
No new doc should be added at the main Documentation/ directory.
Instead, new docs should be added as ReST files, within the
Kernel documentation body.
Fixes: 51bd6f2915 ("Add support for IPMB driver")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Message-Id: <d23c36ca65fe6ad56af1723bf70f7a7f4154c410.1561804596.git.mchehab+samsung@kernel.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
106 lines
3.3 KiB
ReStructuredText
106 lines
3.3 KiB
ReStructuredText
==============================
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IPMB Driver for a Satellite MC
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==============================
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The Intelligent Platform Management Bus or IPMB, is an
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I2C bus that provides a standardized interconnection between
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different boards within a chassis. This interconnection is
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between the baseboard management (BMC) and chassis electronics.
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IPMB is also associated with the messaging protocol through the
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IPMB bus.
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The devices using the IPMB are usually management
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controllers that perform management functions such as servicing
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the front panel interface, monitoring the baseboard,
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hot-swapping disk drivers in the system chassis, etc...
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When an IPMB is implemented in the system, the BMC serves as
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a controller to give system software access to the IPMB. The BMC
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sends IPMI requests to a device (usually a Satellite Management
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Controller or Satellite MC) via IPMB and the device
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sends a response back to the BMC.
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For more information on IPMB and the format of an IPMB message,
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refer to the IPMB and IPMI specifications.
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IPMB driver for Satellite MC
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----------------------------
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ipmb-dev-int - This is the driver needed on a Satellite MC to
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receive IPMB messages from a BMC and send a response back.
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This driver works with the I2C driver and a userspace
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program such as OpenIPMI:
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1) It is an I2C slave backend driver. So, it defines a callback
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function to set the Satellite MC as an I2C slave.
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This callback function handles the received IPMI requests.
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2) It defines the read and write functions to enable a user
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space program (such as OpenIPMI) to communicate with the kernel.
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Load the IPMB driver
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--------------------
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The driver needs to be loaded at boot time or manually first.
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First, make sure you have the following in your config file:
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CONFIG_IPMB_DEVICE_INTERFACE=y
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1) If you want the driver to be loaded at boot time:
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a) Add this entry to your ACPI table, under the appropriate SMBus::
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Device (SMB0) // Example SMBus host controller
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{
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Name (_HID, "<Vendor-Specific HID>") // Vendor-Specific HID
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Name (_UID, 0) // Unique ID of particular host controller
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:
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:
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Device (IPMB)
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{
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Name (_HID, "IPMB0001") // IPMB device interface
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Name (_UID, 0) // Unique device identifier
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}
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}
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b) Example for device tree::
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&i2c2 {
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status = "okay";
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ipmb@10 {
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compatible = "ipmb-dev";
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reg = <0x10>;
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};
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};
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2) Manually from Linux::
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modprobe ipmb-dev-int
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Instantiate the device
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----------------------
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After loading the driver, you can instantiate the device as
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described in 'Documentation/i2c/instantiating-devices'.
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If you have multiple BMCs, each connected to your Satellite MC via
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a different I2C bus, you can instantiate a device for each of
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those BMCs.
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The name of the instantiated device contains the I2C bus number
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associated with it as follows::
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BMC1 ------ IPMB/I2C bus 1 ---------| /dev/ipmb-1
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Satellite MC
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BMC1 ------ IPMB/I2C bus 2 ---------| /dev/ipmb-2
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For instance, you can instantiate the ipmb-dev-int device from
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user space at the 7 bit address 0x10 on bus 2::
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# echo ipmb-dev 0x1010 > /sys/bus/i2c/devices/i2c-2/new_device
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This will create the device file /dev/ipmb-2, which can be accessed
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by the user space program. The device needs to be instantiated
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before running the user space program.
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