^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) ==============================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) IPMB Driver for a Satellite MC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) ==============================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) The Intelligent Platform Management Bus or IPMB, is an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) I2C bus that provides a standardized interconnection between
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) different boards within a chassis. This interconnection is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) between the baseboard management (BMC) and chassis electronics.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) IPMB is also associated with the messaging protocol through the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) IPMB bus.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) The devices using the IPMB are usually management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) controllers that perform management functions such as servicing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) the front panel interface, monitoring the baseboard,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) hot-swapping disk drivers in the system chassis, etc...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) When an IPMB is implemented in the system, the BMC serves as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) a controller to give system software access to the IPMB. The BMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) sends IPMI requests to a device (usually a Satellite Management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) Controller or Satellite MC) via IPMB and the device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) sends a response back to the BMC.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) For more information on IPMB and the format of an IPMB message,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) refer to the IPMB and IPMI specifications.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) IPMB driver for Satellite MC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) ----------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) ipmb-dev-int - This is the driver needed on a Satellite MC to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) receive IPMB messages from a BMC and send a response back.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) This driver works with the I2C driver and a userspace
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) program such as OpenIPMI:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 1) It is an I2C slave backend driver. So, it defines a callback
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) function to set the Satellite MC as an I2C slave.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) This callback function handles the received IPMI requests.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 2) It defines the read and write functions to enable a user
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) space program (such as OpenIPMI) to communicate with the kernel.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) Load the IPMB driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) --------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) The driver needs to be loaded at boot time or manually first.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) First, make sure you have the following in your config file:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) CONFIG_IPMB_DEVICE_INTERFACE=y
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 1) If you want the driver to be loaded at boot time:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) a) Add this entry to your ACPI table, under the appropriate SMBus::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) Device (SMB0) // Example SMBus host controller
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) Name (_HID, "<Vendor-Specific HID>") // Vendor-Specific HID
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) Name (_UID, 0) // Unique ID of particular host controller
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) Device (IPMB)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) Name (_HID, "IPMB0001") // IPMB device interface
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) Name (_UID, 0) // Unique device identifier
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) b) Example for device tree::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) &i2c2 {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) status = "okay";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) ipmb@10 {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) compatible = "ipmb-dev";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) reg = <0x10>;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) i2c-protocol;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) If xmit of data to be done using raw i2c block vs smbus
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) then "i2c-protocol" needs to be defined as above.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) 2) Manually from Linux::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) modprobe ipmb-dev-int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) Instantiate the device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) ----------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) After loading the driver, you can instantiate the device as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) described in 'Documentation/i2c/instantiating-devices.rst'.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) If you have multiple BMCs, each connected to your Satellite MC via
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) a different I2C bus, you can instantiate a device for each of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) those BMCs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) The name of the instantiated device contains the I2C bus number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) associated with it as follows::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) BMC1 ------ IPMB/I2C bus 1 ---------| /dev/ipmb-1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) Satellite MC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) BMC1 ------ IPMB/I2C bus 2 ---------| /dev/ipmb-2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) For instance, you can instantiate the ipmb-dev-int device from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) user space at the 7 bit address 0x10 on bus 2::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) # echo ipmb-dev 0x1010 > /sys/bus/i2c/devices/i2c-2/new_device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) This will create the device file /dev/ipmb-2, which can be accessed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) by the user space program. The device needs to be instantiated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) before running the user space program.
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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