RedBoot User's Guide
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# ARM/Intel XScale IXDP425 Network Processor Evaluation Board

## Overview

RedBoot supports the builtin high-speed and console UARTs and a PCI based i82559 ethernet card for communication and downloads. The default serial port settings are 115200,8,N,1. RedBoot also supports flash management for the 16MB boot flash on the mainboard.

The following RedBoot configurations are supported:

Configuration | Mode | Description | File
--- | --- | --- | ---
ROM | [ROM] | RedBoot running from flash sector. | redboot_ROM.ecm
RAM | [RAM] | RedBoot running from RAM with RedBoot in the flash boot sector. | redboot_RAM.ecm

## Initial Installation Method

The IXDP425 flash is socketed, so initial installation may be done using an appropriate device programmer. JTAG based initial may also be used. In either case, the ROM mode RedBoot is programmed into the boot flash at address 0x00000000.

After booting the initial installation of RedBoot, this warning may be printed:

    flash configuration checksum error or invalid key

This is normal, and indicates that the flash should be configured for use by RedBoot. See the Section called Persistent State Flash-based Configuration and Control in Chapter 2 for more details.

## LED Codes

RedBoot uses the 4 digit LED display to indicate status during board initialization. Possible codes are:

LED Actions
-------------------------------------------------------------
Power-On/Reset
Set the CPSR
Enable coprocessor access
Drain write and fill buffer
Setup expansion bus chip selects
1001
Enable Icache
1002
Initialize SDRAM controller
1003
Switch flash (CS0) from 0x00000000 to 0x50000000
1004
Copy MMU table to RAM
1005
Setup TTB and domain permissions
1006
Enable MMU
1007
Enable DCache
1008
Enable branch target buffer
1009
Drain write and fill buffer
Flush caches
100A
Start up the eCos kernel or RedBoot
0001

## Rebuilding RedBoot

These shell variables provide the platform-specific information needed for building RedBoot according to the procedure described in Chapter 3:

    export TARGET=ixdp425
    export ARCH_DIR=arm
    export PLATFORM_DIR=xscale/ixdp425

The names of configuration files are listed above with the description of the associated modes.

## Interrupts

RedBoot uses an interrupt vector table which is located at address 0x8004. Entries in this table are pointers to functions with this protoype::

    int irq_handler( unsigned vector, unsigned data )

On the IXDP425 board, the vector argument is one of many interrupts defined in `hal/arm/xscale/ixp425/current/include/hal_var_ints.h:`:

    #define CYGNUM_HAL_INTERRUPT_NPEA         0
    #define CYGNUM_HAL_INTERRUPT_NPEB         1
    #define CYGNUM_HAL_INTERRUPT_NPEC         2
    #define CYGNUM_HAL_INTERRUPT_QM1          3
    #define CYGNUM_HAL_INTERRUPT_QM2          4
    #define CYGNUM_HAL_INTERRUPT_TIMER0       5
    #define CYGNUM_HAL_INTERRUPT_GPIO0        6
    #define CYGNUM_HAL_INTERRUPT_GPIO1        7
    #define CYGNUM_HAL_INTERRUPT_PCI_INT      8
    #define CYGNUM_HAL_INTERRUPT_PCI_DMA1     9
    #define CYGNUM_HAL_INTERRUPT_PCI_DMA2     10
    #define CYGNUM_HAL_INTERRUPT_TIMER1       11
    #define CYGNUM_HAL_INTERRUPT_USB          12
    #define CYGNUM_HAL_INTERRUPT_UART2        13
    #define CYGNUM_HAL_INTERRUPT_TIMESTAMP    14
    #define CYGNUM_HAL_INTERRUPT_UART1        15
    #define CYGNUM_HAL_INTERRUPT_WDOG         16
    #define CYGNUM_HAL_INTERRUPT_AHB_PMU      17
    #define CYGNUM_HAL_INTERRUPT_XSCALE_PMU   18
    #define CYGNUM_HAL_INTERRUPT_GPIO2        19
    #define CYGNUM_HAL_INTERRUPT_GPIO3        20
    #define CYGNUM_HAL_INTERRUPT_GPIO4        21
    #define CYGNUM_HAL_INTERRUPT_GPIO5        22
    #define CYGNUM_HAL_INTERRUPT_GPIO6        23
    #define CYGNUM_HAL_INTERRUPT_GPIO7        24
    #define CYGNUM_HAL_INTERRUPT_GPIO8        25
    #define CYGNUM_HAL_INTERRUPT_GPIO9        26
    #define CYGNUM_HAL_INTERRUPT_GPIO10       27
    #define CYGNUM_HAL_INTERRUPT_GPIO11       28
    #define CYGNUM_HAL_INTERRUPT_GPIO12       29
    #define CYGNUM_HAL_INTERRUPT_SW_INT1      30
    #define CYGNUM_HAL_INTERRUPT_SW_INT2      31

The data passed to the ISR is pulled from a data table `(hal_interrupt_data)` which immediately follows the interrupt vector table. With 32 interrupts, the data table starts at address 0x8084.

An application may create a normal C function with the above prototype to be an ISR. Just poke its address into the table at the correct index and enable the interrupt at its source. The return value of the ISR is ignored by RedBoot.

## Memory Maps

The RAM based page table is located at RAM start + 0x4000.

> NOTE: The virtual memory maps in this section use a C, B, and X column to indicate the caching policy for the region..

    X C B  Description
    - - -  ---------------------------------------------
    0 0 0  Uncached/Unbuffered
    0 0 1  Uncached/Buffered
    0 1 0  Cached/Buffered    Write Through, Read Allocate
    0 1 1  Cached/Buffered    Write Back, Read Allocate
    1 0 0  Invalid -- not used
    1 0 1  Uncached/Buffered  No write buffer coalescing
    1 1 0  Mini DCache - Policy set by Aux Ctl Register
    1 1 1  Cached/Buffered    Write Back, Read/Write Allocate

    Virtual Address   Physical Address  XCB  Size (MB)  Description
    ---------------   ----------------  ---  ---------  -----------
       0x00000000       0x00000000      010     256     SDRAM (cached)
       0x10000000       0x10000000      010     256     SDRAM (alias)
       0x20000000       0x00000000      000     256     SDRAM (uncached)
       0x48000000       0x48000000      000      64     PCI Data
       0x50000000       0x50000000      010      16     Flash (CS0)
       0x51000000       0x51000000      000     112     CS1 - CS7
       0x60000000       0x60000000      000      64     Queue Manager
       0xC0000000       0xC0000000      000       1     PCI Controller
       0xC4000000       0xC4000000      000       1     Exp. Bus Config
       0xC8000000       0xC8000000      000       1     Misc IXP425 IO
       0xCC000000       0xCC000000      000       1     SDRAM Config

## Platform Resource Usage

The IXP425 programmable OStimer0 is used for timeout support for networking and XModem file transfers.

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