x86 PCI DT details:
===================
Some options are available to affect how PCI operates on x86.
Optional properties:
- u-boot,skip-auto-config-until-reloc : Don't set up PCI configuration until
after U-Boot has relocated. Normally if PCI is used before relocation,
this happens before relocation also. Some platforms set up static
configuration in TPL/SPL to reduce code size and boot time, since these
phases only know about a small subset of PCI devices.
For PCI devices the following optional property is available:
- pci,no-autoconfig : Don't automatically configure this PCI device at all.
This is used when the device is statically configured and must maintain
this same config throughout the boot process. An example is a serial
UART being used to debug PCI configuration, since reconfiguring it stops
the UART from working until the driver is re-probed, and this can cause
output to be lost. This should not generally be used in production code,
although it is often harmless.
- u-boot,pci-pre-reloc : List of vendor/device IDs to bind before relocation, even
if they are not bridges. This is useful if the device is needed (e.g. a
UART). The format is 0xvvvvdddd where d is the device ID and v is the
vendor ID.
Example:
pci {
compatible = "pci-x86";
#address-cells = <3>;
#size-cells = <2>;
bootph-all;
ranges = <0x02000000 0x0 0xc0000000 0xc0000000 0 0x10000000
0x42000000 0x0 0xb0000000 0xb0000000 0 0x10000000
0x01000000 0x0 0x1000 0x1000 0 0xefff>;
u-boot,skip-auto-config-until-reloc;
u-boot,pci-pre-reloc = <
PCI_VENDEV(PCI_VENDOR_ID_INTEL,
PCI_DEVICE_ID_INTEL_APL_UART2)>;
serial: serial@18,2 {
reg = <0x0200c210 0 0 0 0>;
bootph-all;
compatible = "intel,apl-ns16550";
early-regs = <0xde000000 0x20>;
reg-shift = <2>;
clock-frequency = <1843200>;
current-speed = <115200>;
pci,no-autoconfig;
};
};