A bit more than a month after publishing the datasheet of the Armada 370 processor, Marvell has now released a similar datasheet for the more powerful Armada XP processor. The datasheet is available as a PDF document, with no registration, at http://www.marvell.com/embedded-processors/armada-xp/assets/ARMADA-XP-Functional-SpecDatasheet.pdf, with a link to it clearly visible on the Armada XP product page.
As most of our readers probably know, Bootlin has been working and continues to work significantly on the Linux kernel support for Marvell processors. Thanks to this work done for more than two years now, the mainline Linux kernel has pretty good support for the Armada XP processor. This processor is a nice monster: up to 4 cores (PJ4B cores, which are roughly equivalent to Cortex-A9 but with LPAE support), up to 10 PCIe interfaces, multiple SATA interfaces, up to four Gigabit network interfaces, and many, many other things (XOR engine, cryptographic engine, etc.). Many of the processor features are already supported in mainline, and lately we’ve been focusing on power management features: cpuidle support for Armada XP will be part of 3.16, cpufreq support will either be part of 3.17 or 3.18, and suspend/resume should hopefully be part of 3.18.
The Armada XP processor is used in publicly available products:
At Bootlin, we are again really happy to see Marvell opening this datasheet, as it will allow all community developers to further improve support for this processor in the Linux kernel, but also in other open-source projects.
Over the last two years, Bootlin has contributed support for the Marvell Armada 370 and Marvell Armada XP processors to the mainline Linux kernel. These ARM processors are used mainly in Network Attached Storage devices but also in other devices such as printers. Until now the datasheet for these processors was only available for Marvell customers and partners under NDA, but last week, Marvell finally released the datasheet of the Armada 370 publicly, with no restriction, no registration, no NDA. The Armada 370 processor can already be found in several consumer grade products:
From now on, on the Marvell page (broken link removed) related to the Armada 3xx family, the Armada 370 Functional Specification (broken link removed) as well as the Armada 370 Hardware Specifications (broken link removed) can be found. While the Armada XP datasheet is not available at this time, it is worth mentioning that the vast majority of the peripherals are exactly the same between Armada 370 and Armada XP, so even Armada XP users will find useful information in this datasheet.
Bootlin is happy to see that Marvell is making more and more progress towards mainlining their kernel support and opening their datasheets publicly. We strongly believe that the openness of these datasheets will allow hobbyists and developers to improve the support for Armada 370 in the open-source ecosystem, be it in the Linux kernel, in bootloaders like U-Boot or Barebox or even in other projects.
Barebox is a bootloader that strives to be a modern alternative to U-Boot. It currently supports ARM, Blackfin, MIPS, NIOS2, OpenRISC, PowerPC and x86 as CPU architectures, and while it doesn’t have as much hardware support as U-Boot yet, it does have a number of very significant advantages over U-Boot: a proper device model very similar to the one used in the Linux kernel, which makes the code very clean and nice, and a configuration system that uses kconfig, like the Linux kernel, which is a lot better than the per-board header files used by U-Boot with lots of cryptic macros.
Bootlin had already contributed to Barebox in the past, as our engineer Maxime Ripard added the support for the Crystalfontz i.MX28 boards.
More recently, we contributed basic support for the Marvell Kirkwood, Marvell Armada 370 and Marvell Armada XP ARM processors. This work was released as part of the 2013.07.0 release. For now, the support is fairly minimal, as it only allows to boot a Barebox bootloader that has serial port support. The most important part of the work was to write a kwbimage tool (see kwbimage.c), which allows to generate bootable images for Marvell processors. Our work contained minimal support for the Armada XP-based OpenBlocks AX3 board, the Armada XP-based GP development board, the Armada 370-based Mirabox from Globalscale and the Kirkwood-based Guruplug from Globalscale. Our work was quickly extended by Sebastian Hesselbarth, who added basic support for the Marvell Dove processor, and the Cubox platform from SolidRun, which uses the Dove processor.
Of course, such support is far from being complete, we are hoping in the future to add support for network, NAND and SD, in order to make Barebox really useful and usable on Marvell platforms.
The details of our contributions are: