Creating A devicetree.cb
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This article should help people who are writting a devicetree.cb for their system.
What you will need
While running GNU/Linux on the vendor BIOS, collect the output from:
- dmesg
- lspci -ntvvv
- cat /proc/ioports
If you have support for your board in serialice you may wish to gather its output also.
Reading lspci output
The Peripheral Component Interconnect (PCI) is a standerdized local bus for attaching different hardwares to motherboard.
The lspci command reads the bus information and topology, its output format is given by example:
03:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01) 13:45, 2 March 2014 (UTC)~~ 13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)Eocallaghan (talk) 13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)13:45, 2 March 2014 (UTC)Eocallaghan (talk) ^ ^ ^ | | | | | Field 3: Name of device attached and its manufactured company name. | Field 2: PCI slot name. Field 1: PCI bus slot number.
Introduction
The mainboard's devicetree.cb file contains many build and platform configuration settings. One of the most important items is the mainboard device list.
A device needs to be listed in the mainboard devicetree.cb if it requires more setup than standard PCI initialization (resource allocation). Typically, that includes the CPU, northbridge, southbridge, and Super I/O. These devices are usually required for system specific configuration as well as indicate the system bus structure (pci_domain).
When a device in devicetree.cb is found during the coreboot PCI/system scan process the functions to do customized initialization are called via the device_operations and the chip_operations structures. You will find these structures in the devices source files.
Keywords & Symbols
<source lang="ada"> chip, device, register,on,off,pci,ioapic,pnp,i2c,lapic,cpu_cluster,domain,irq,drq,io,ioapic_irq,inherit,subsystemid,end,= </source>
Syntax
- ioapic_irq
<source lang="ada"> ioapic_irq: ioapic_irq number-literal pciint number-literal </source>
rewrite this in BNF notation..
Grammar
Literals
Literal values types are defined and thus consumed by the following regular expressions:
- Hex
<source lang="reg"> 0x[0-9a-fA-F.]+
[0-9a-fA-F.]+ </source>
- Decimals
<source lang="reg"> [0-9.]+ </source>
- PCI Interrupts
<source lang="reg"> INT[A-D] </source>
- Strings
<source lang="reg"> \"[^\"]+\"
[^ \n\t]+ </source>
NOTES
See source util/sconfig/sconfig.* for devicetree compiler..
Examples
NorthBridge
..
Super I/O
» chip superio/fintek/f71869ad » » device pnp 4e.00 off # Floppy » » » io 0x60 = 0x3f0 » » » irq 0x70 = 6 » » » drq 0x74 = 2 » » end » » device pnp 4e.01 on # COM1 » » » io 0x60 = 0x3f8 » » » irq 0x70 = 4 » » end » » » device pnp 4e.02 off # COM2 » » » io 0x60 = 0x2f8 » » » irq 0x70 = 3 » » end » » device pnp 4e.03 off # Parallel Port » » » io 0x60 = 0x378 » » » irq 0x70 = 7 » » » drq 0x74 = 3 » » end » » device pnp 4e.04 on # Hardware Monitor » » » io 0x60 = 0x295 » » » irq 0x70 = 0 » » end » » device pnp 4e.05 on # KBC » » » io 0x60 = 0x060 » » » irq 0x70 = 1 # Keyboard IRQ » » » irq 0x72 = 12 # Mouse IRQ » » end » » device pnp 4e.06 off end # GPIO » » device pnp 4e.07 on end # BSEL » » device pnp 4e.0a off end # PME » end # f71869ad
 
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