Alternate Boot Device

Some Gateworks Laguna family products have an 'Alternate boot device' that can be used for alternate firmware images, such as a flash recovery image.

Please note that if you have a board with a 4MB SPI flash device, such as the GW2388-4 you will need to use u-boot-2014.10 cns3xxx bootloader.

There are 2 ways that you can instruct the 'Gateworks System Controller' to boot to the alternate boot device (an SPI FLASH device) vs the primary boot device (a NOR FLASH device):

  1. set GSC R0.3 and press the user pushbutton 5x times to perform a 1-time hard reboot to the alternate boot device
    i2cset -f -y 0 0x20 0 0x08
  2. set GSC R1.6 (SWITCH_BOOT_ENABLE) to enable 'switch boot check'. If this is set when the board powers on, it will 'toggle' boot device selection and reboot after 30 seconds unless GSC R1.7 (SWITCH_BOOT_CLEAR) has been set before that time. Note that the countdown timer is only activated when the board powers on from a GSC sleep or unpowered state

Flash Mapping

This is an example from a Laguna 2388 with 16MB NOR and 4MB SPI. The mapping is set by us but can be changed.

root@(none):/# cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00040000 00020000 "uboot"
mtd1: 00020000 00020000 "params"
mtd2: 00200000 00020000 "kernel"
mtd3: 00da0000 00020000 "rootfs"
mtd4: 007c0000 00020000 "rootfs_data"
mtd5: 00040000 00010000 "uboot"
mtd6: 00040000 00010000 "params"
mtd7: 00180000 00010000 "kernel"
mtd8: 00200000 00010000 "rootfs"

Auto Switch Boot Device

The Gateworks System Controller implements an 'Auto Switch Boot Device' feature that can be useful as a firmware recovery mechanism. GSC register R1.6 (SWITCH_BOOT_ENABLE) enables this mode. When this is set and the board powers on it will initiate a countdown timer that expires in 30 seconds. Writing a 1 to GSC R1.7 (SWITCH_BOOT_CLEAR) will cancel this timer. If the timer expires the boot device will be 'toggled' and the board will be hard reset.

If you need to progamattically hard power cycle the board you can put it to sleep for a few seconds.

From Linux

Within the linux command-line shell, you can use i2cset from the i2c-tools package.

To enable 'switch boot check':

i2cset -f -y 0 0x20 1 0x40      ;# enable R1.6 (SWITCH_BOOT_ENABLE)

To assert 'SWITCH_BOOT_CLEAR' and cancel the countdown timer (within 30 seconds of power up):

i2cset -f -y 0 0x20 1 0xC0      ;# cancel countdown by asserting R1.7 (SWITCH_BOOT_CLEAR) but keep enabled R1.6 (SWITCH_BOOT_ENABLE)
# or
i2cset -f -y 0 0x20 1 0x80      ;# cancel countdown by asserting R1.7 (SWITCH_BOOT_CLEAR) and disable R1.6 (SWITCH_BOOT_ENABLE)

To programatically hard power-cycle the board by putting it to sleep for a few seconds while also enabling 'switch boot':

# power cycle board: must be a hard power cycle, not a soft reboot (which can be done manually or via sleep/wake timer control)
i2cset -f -y 0 0x20 6 5 	;# write add timer to 5sec
i2cset -f -y 0 0x20 7 0
i2cset -f -y 0 0x20 8 0
i2cset -f -y 0 0x20 9 0
i2cset -f -y 0 0x20 1 0x04 	;# set add time bit (must be a separate i2c transaction than activating sleep)
i2cset -f -y 0 0x20 1 0x43 	;# enable R1.6 (SWITCH_BOOT_ENABLE), sleep operation (R1.0) and activate sleep (R1.1)
# wait for board to reboot into linux and within 30 seconds of powerup cancel the boot timer
i2cset -f -y 0 0x20 1 0xC0      ;# set R1.7 (SWITCH_BOOT_CLEAR) to cancel timer but leave R1.6 (SWITCH_BOOT_ENABLE) enabled

From u-boot

Within the u-boot environment you can use the imw command to set i2c registers.

To enable 'switch boot check':

Laguna > imw 0x20 1 0x40 1     ;# enable R1.6 (SWITCH_BOOT_ENABLE)

To assert R1.7 (SWITCH_BOOT_CLEAR) and cancel the countdown timer (within 30 seconds of power up):

Laguna > imw 0x20 1 0xc0 1  # set SWITCH_BOOT_CLEAR (R1.7)

To programatically hard power-cycle the board by putting it to sleep for a few seconds while also enabling 'switch boot':

Laguna > imw 0x20 6 0x05 1  # LSB (5 secs)
Laguna > imw 0x20 7 0x00 1
Laguna > imw 0x20 8 0x00 1
Laguna > imw 0x20 9 0x00 1  # MSB
Laguna > imw 0x20 1 0x04 1  # latch R6-R9 and add to RTC
Laguna > imw 0x20 1 0x43 1  # set SWITCH_BOOT_ENABLE (R1.6), sleep operation (R1.0) and activate sleep (R1.1)

Alternate Boot Flash firmware images

Step 1. Bootloader

The alternate boot device and the primary boot device require different bootloaders (SPI vs NOR FLASH). Only the primary boot device is programmed with a bootable image by Gateworks. In order to program the alternate boot device you will need to do so from Linux (as u-boot-nor.bin on the primary boot device without modification can only access NOR flash).

REQUIRED: You will also need to modify your Linux kernel to allow writing to the u-boot partition of SPI flash by commenting out the '.mask_flags = MTD_WRITEABLE' in the laguna_spi_partitions structure in:

/gateworks-openwrt/trunk$ vi build_dir/target-arm_v6k_uClibc-

Once modified, recompile the BSP. Then flash this to the NOR flash on your board.

Once booted to NOR flash with this modified kernel you can write the laguna u-boot-spi.bin to /dev/mtd5 via mtd:

root@OpenWrt:/# mtd write u-boot_spi.bin /dev/mtd5
Unlocking /dev/mtd5 ...

Writing from u-boot_spi.bin to /dev/mtd5 ...     

Now you can follow the instructions above to boot off the Alternate Boot Device (SPI Flash) and setup your kernel/rootfs using the instructions for an SPI FLASH device such as the GW2380 found here here

Step 2. Kernel / Root Filesystem

Depending on the size of the SPI FLASH you will likely need to prune features from your kernel/filesystem. A good starting point may be the Laguna test_config file which uses a ramdisk and a minimal set of utilities used by Gateworks to test boards. As this OpenWrt config file specifies an INTRAMFS ramdisk, you only need to flash the kernel which includes the root filesystem.

  1. Use the instructions above to boot from the Alternate Boot Device (SPI FLASH) and break out into the bootloader. You can determine that you are booted to the Alternate Boot Device by seeing a smaller FLASH size in the boot header or by looking at the output of 'printenv bootcmd' and seeing that it boots a kernel from 0x60080000 (SPI FLASH) instead of 0x10080000 (NOR FLASH)
    Hit any key to stop autoboot:  0 
    Laguna> printenv bootcmd
    bootcmd=bootm 0x60080000
  1. set R1.7 (SWITCH_BOOT_CLEAR) so that you have plenty of time to write the kernel to the SPI Flash:
    Laguna > imw 0x20 1 0xc0 1  # set SWITCH_BOOT_CLEAR (R1.7)
  1. set ipaddr/serverip according to your network. For example if your server is at and your target is to be
    Laguna> sete ipaddr
    Laguna> sete serverip
  1. Erase what is currently in the SPI FLASH: (This is a range, start and end for a specific flash size. Example 16MB SPI below)
    Laguna> erase 0x60080000 0x60ffffff
  1. Copy Kernel+Root-filesystem to the Board
    Laguna> tftpboot 0x00800000 laguna/openwrt-cns3xxx-uImage_ramdisk
    Laguna> cp.b 0x00800000 0x60080000 $(filesize)
  1. Set kernel commandline for booting a ramdisk:
    setenv bootargs 'console=ttyS0,115200 root=/dev/ram0 rootfstype=ramfs'
  1. Boot into Linux
    Laguna> bootm


  • when using the SPI FLASH device you can erase the u-boot env flash section and restore factory defaults with:
    Laguna> protect off 0x60040000 +0x40000
    Laguna> erase 0x60040000 +0x40000
    Laguna> reset

Using u-boot-2014.10-cns3xxx bootloader

If using the u-boot-2014.10-cns3xxx which supports both the 16MB and 4MB SPI flash devices used on Laguna products, you will need to use the 'sf' commands within uboot to access flash.

Update kernel:

setenv serverip
setenv ipaddr
setenv spi_koffset 0x80000
setenv spi_klen 0x180000
setenv spi_roffset 0x200000
# update kernel
tftp ${loadaddr} laguna/openwrt-cns3xxx-uImage && sf probe && sf update ${loadaddr} ${spi_koffset} ${filesize}

Update SPI uboot:

# update SPI uboot
setenv serverip
setenv ipaddr
tftp ${loadaddr} laguna/u-boot_spi.bin && sf probe && sf update ${loadaddr} 0 ${filesize}

Enable Alternate Boot timer:

i2c mw 0x20 1 0x40 1 # set R1.6 SWITCH_BOOT_ENABLE

Clear Alternate Boot timer:

i2c mw 0x20 1 0xc0 1 # set R1.7 SWITCH_BOOT_CLEAR
Last modified 2 years ago Last modified on 04/08/15 06:27:13