Thomas Petazzoni – Page 24

“Porting Linux on ARM” seminar road show in France

In December 2015, Bootlin engineer Alexandre Belloni gave a half-day seminar “Porting Linux on ARM” in Toulouse (France) in partnership with french organization Captronic. We published the materials used for the seminar shortly after the event.

We are happy to announce that this seminar will be given in four different cities in France over the next few months:

In Montpellier, on April 14th from 2 PM to 6 PM. See this page for details.
In Clermont-Ferrand, on April 27th from 2 PM to 6 PM. See this page for details.
In Brive, on April 28th from 9 AM to 1 PM. See this page for details.
Near Chambéry, on May 25th from 9:30 AM to 5/30 PM. See this page for details.
Near Bordeaux, on June 2nd from 2 PM to 6 PM. See this page for details.
Near Nancy, on June 16th from 2 PM to 6 PM. See this page for details.

The seminar is delivered in French, and the event is free after registration. The speaker, Alexandre Belloni, has worked on porting botloaders and the Linux kernel on a number of ARM platforms (Atmel, Freescale, Texas Instruments and more) and is the Linux kernel co-maintainer for the RTC subsystem and the support of the Atmel ARM processors.

Bootlin at the Embedded Linux Conference 2016

Like every year for about 10 years, the entire Bootlin engineering team will participate to the next Embedded Linux Conference, taking place on April 4-6 in San Diego, California. For us, participating to such conferences is very important, as it allows to remain up to date with the latest developments in the embedded Linux world, create contacts with other members of the embedded Linux community, and meet the community members we already know and work with on a daily basis via the mailing lists or IRC.

Embedded Linux Conference 2016

Over the years, our engineering team has grown, and with the arrival of two more engineers on March 14, our engineering team now gathers 9 persons, all of whom are going to participate to the Embedded Linux Conference.

As usual, in addition to attending, we also proposed a number of talks, and some of them have been accepted and are visible in the conference schedule:

Buildroot vs. OpenEmbedded/Yocto: A Four Hands Discussion, Alexandre Belloni & Thomas Petazzoni
Using DT Overlays to Support the C.H.I.P.’s Capes, Antoine Tenart
Modernizing the NAND framework: The Big Picture, Boris Brezillon
Bringing Display and 3D to the C.H.I.P Computer, Maxime Ripard
Autotools: A Demystification Tutorial, Thomas Petazzoni

As usual, our talks are centered around our areas of expertise: hardware support in the Linux kernel, especially for ARM platforms, and build system related topics (Buildroot, Yocto, autotools).

We are looking forward to attending this event, and see many other talks from various speakers: the proposed schedule contains a wide range of topics, many of which look really interesting!

Bootlin speaking at the Linux Collaboration Summit

Bootlin engineers are regular speakers at the Embedded Linux Conference and Embedded Linux Conference Europe events from the Linux Foundation, to which our entire engineering team participates each year.

In 2016, for the first time, we will also be speaking at the Collaboration Summit, an invitation-only event where, as the Linux Foundation presents it, “the world’s thought leaders in open source software and collaborative development convene to share best practices and learn how to manage the largest shared technology investments of our time”.

Collaboration Summit 2016

This event will take place on March 29-31 in Lake Tahoe, California, and the event schedule has been published recently. Bootlin CTO Thomas Petazzoni will be giving a talk Upstreaming hardware support in the Linux kernel: why and how?, during which we will share our experience working with HW manufacturers to bring the support for their hardware to the upstream Linux kernel, discuss the benefits of upstreaming, and best practices to work with upstream.

With a small team of engineers, Bootlin has merged over the last few years thousands of patches in the official Linux kernel, and has several of its engineers having maintainer positions in the Linux kernel community. We are happy to take the opportunity of the Collaboration Summit to share some of our experience, and hopefully encourage and help other companies to participate upstream.

Initial support for ARM64 Marvell Armada 7K/8K platform

Two weeks ago, we submitted the initial support for the Marvell Armada 3700, which was the first ARM64 platform that Bootlin engineers contributed to the upstream Linux kernel.

Today, we submitted initial support for another Marvell ARM64 platform, the Armada 7K and Armada 8K platform. Compared to the Armada 3700, the Armada 7K and 8K are much more on the high-end side: they use a dual Cortex-A72 or a quad Cortex-A72, as opposed to the Cortex-A53 for the Armada 3700.

The Armada 7K and 8K also use a fairly unique architecture, internally they are composed of several components:

One AP (Application Processor), which contains the processor itself and a few core hardware blocks. The AP used in the Armada 7K and 8K is called AP806, and is available in two configurations: dual Cortex-A72 and quad Cortex-A72.
One or two CP (Communication Processor), which contain most of the I/O interfaces (SATA, PCIe, Ethernet, etc.). The 7K family chips have one CP, while the 8K family chips integrate two CPs, providing two times the number of I/O interfaces available in the CP. The CP used in the 7K and 8K is called CP110.

All in all, this gives the following combinations:

Armada 7020, which is a dual Cortex-A72 with one CP
Armada 7040, which is a quad Cortex-A72 with one CP
Armada 8020, which is a dual Cortex-A72 with two CPs
Armada 8040, which is a quad Cortex-A72 with two CPs

So far, we submitted initial support only for the AP806 part of the chip, with the following patch series:

[PATCH 0/3] clk: mvebu: initial support for AP806 clocks, adding two new clock drivers for the main clocks of the AP806
[PATCH] irqchip: irq-mvebu-odmi: new driver, adding a new irqchip driver to control a MSI controller that can be used by on-board devices
[PATCH] dma: mv_xor_v2: new driver, adding a new dmaengine driver to accelerate copy and XOR operations, used mainly for RAID5
[PATCH 0/5] arm64: Initial support for Marvell Armada 7K/8K, adding the initial support for the platform itself, with mainly the Device Tree files

We will continue to submit more and more patches to support other features of the Armada 7K and 8K processors in the near future.

Bootlin contributes Linux support for a first ARM64 platform: Marvell Armada 3700

Over the last years, Bootlin has become a strong participant to the Linux ARM kernel community, with our engineers upstreaming support for numerous ARM 32 bits platforms.

Now, with ARM64 becoming more and more mainstream, our focus in 2016 will shift towards this architecture, and we’re happy to announce that we have recently contributed to the upstream Linux kernel the initial support for our first ARM64 architecture: the Marvell Armada 3700.

This new SoC from Marvell is available in single-core and dual-core Cortex-A53 configurations, and features a wide range of peripherals: 2 Gigabit Ethernet controllers, USB 3.0 and 2.0, SATA, PCIe interfaces, DMA engines for XOR acceleration, and of course the usual SPI, I2C, UART, GPIO, SDIO interfaces. For more details, see the Product Brief.

So far, we have sent a patch series adding minimal support for this platform:

A UART driver, since this SoC uses a new specific UART controller
Small changes to an AHCI driver to support SATA.
The Device Tree files describing the SoC and the currently available development board. So far, only the CPU, timers, UART0, USB 3.0, SATA and GIC interrupt controllers are described.

A second version of the patch series was sent a few days later, in order to address comments received during the review.

It is worth mentioning that this SoC was publicly announced in a press release on January 6 2016, and we’ve been able to send the initial support patches on February 2, 2016, less than a month later.

We’ll be progressively submitting support for all the other hardware blocks of the Armada 3700, and also be announcing soon our development efforts on several other ARM64 platforms.

Seminar “Porting Linux on an ARM board”, materials available

On December 10th 2015, Bootlin engineer Alexandre Belloni gave a half-day seminar on the topic of Porting Linux on an ARM board in Toulouse, France. This seminar covers topics like porting the bootloader, understanding the concept of the Device Tree, writing Linux device drivers and more. With ~50 persons from various companies attending and lots of questions from the audience, this first edition has been very successful, which shows an increasing interest for using Linux on ARM platforms in the industry.

We are now publishing the 220 slides materials from this seminar, available in PDF format. Like all our training materials, this material is published under the Creative Commons BY-SA 3.0 license, which allows everyone to re-use it for free, provided the derivative works are released under the same license. We indeed re-used quite extensively parts of our existing training materials for this half-day seminar.

We plan to give this half-day seminar in other locations in France in 2016. Contact us if you are interested in organizing a similar seminar in your area (we are happy to travel!).

Device Tree on ARM article in French OpenSilicium magazine

Our French readers are most likely aware of the existence of a magazine called OpenSilicium, a magazine dedicated to embedded technologies, with frequent articles on platforms like the Raspberry Pi, the BeagleBone Black, topics like real-time, FPGA, Android and many others.

Open Silicium #17

Issue #17 of the magazine has been published recently, and features a 14-pages long article Introduction to the Device Tree on ARM, written by Bootlin engineer Thomas Petazzoni.

Open Silicium #17

Besides Thomas article, many other topics are covered in this issue:

A summary of the Embedded Linux Conference Europe 2015 in Dublin
Icestorm, a free development toolset for FPGA
Using the Armadeus APF27 board with Yocto
Set up an embedded Linux system on the Zynq ZedBoard
Debugging with OpenOCD and JTAG
Usage of the mbed SDK on a small microcontroller, the LPC810
From Javascript to VHDL, the art of writing synthetizable code using an imperative language
Optimization of the 3R strems decompression algorithm

Bootlin at FOSDEM and the Buildroot Developers Meeting

The FOSDEM conference will take place on January 30-31 in Brussels, Belgium. Like every year, there are lots of interesting talks for embedded developers, starting from the Embedded, Mobile and Automotive Devroom, but also the Hardware track, the Graphics track. Some talks of the IoT and Security devrooms may also be interesting to embedded developers.

Thomas Petazzoni, embedded Linux engineer and CTO at Bootlin, will be present during the FOSDEM conference. Thomas will also participate to the Buildroot Developers Meeting that will take place on February 1-2 in Brussels, hosted by Google.

Linux 4.4, Bootlin contributions

Linux 4.4 has been released, a week later than the normal schedule in order to allow kernel developers to recover from the Christmas/New Year period. As usual, LWN has covered the 4.4 cycle merge window, in two articles: part 1 and part 2. This time around, KernelNewbies has a nice overview of the Linux 4.4 changes. With 112 patches merged, we are the 20th contributing company by number of patches according to the statistics.

Besides our contributions in terms of patches, some of our engineers have also become over time maintainers of specific areas of the Linux kernel. Recently, LWN.net conducted a study of how the patches merged in 4.4 went into the kernel, which shows the chain of maintainers who pushed the patches up to Linus Torvalds. Bootlin engineers had the following role in this chain of maintainers:

As a co-maintainer of the Allwinner (sunxi) ARM support, Maxime Ripard has submitted a pull request with one patch to the clock maintainers, and pull requests with a total of 124 patches to the ARM SoC maintainers.
As a maintainer of the RTC subsystem, Alexandre Belloni has submitted pull requests with 30 patches directly to Linus Torvalds.
As a co-maintainer of the AT91 ARM support, Alexandre Belloni has submitted pull requests with 46 patches to the ARM SoC maintainers.
As a co-maintainer of the Marvell EBU ARM support, Gregory Clement has submitted pull requests with a total of 33 patches to the ARM SoC maintainers.

Our contributions for the 4.4 kernel were centered around the following topics:

Alexandre Belloni continued some general improvements to support for the AT91 ARM processors, with fixes and cleanups in the at91-reset, at91-poweroff, at91_udc, atmel-st, at91_can drivers and some clock driver improvements.
Alexandre Belloni also wrote a driver for the RV8803 RTC from Microcrystal.
Antoine Ténart added PWM support for the Marvell Berlin platform and enabled the use of cpufreq on this platform.
Antoine Ténart did some improvements in the pxa3xx_nand driver, still in preparation to the addition of support for the Marvell Berlin NAND controller.
Boris Brezillon did a number of improvements to the sunxi_nand driver, used for the NAND controller found on the Allwinner SoCs. Boris also merged a few patches doing cleanups and improvements to the MTD subsystem itself.
Boris Brezillon enabled the cryptographic accelerator on more Marvell EBU platforms by submitting the corresponding Device Tree descriptions, and he also fixed a few bugs found in the driver
Maxime Ripard reworked the interrupt handling of per-CPU interrupts on Marvell EBU platforms especially in the mvneta network driver. This was done in preparation to enable RSS support in the mvneta driver.
Maxime Ripard added support for the Allwinner R8 and the popular C.H.I.P platform.
Maxime Ripard enabled audio support on a number of Allwinner platforms, by adding the necessary clock code and Device Tree descriptions, and also several fixes/improvements to the ALSA driver.

The details of our contributions for 4.4:

Linux 4.3 released, Bootlin contributions inside

The 4.3 kernel release has been released just a few days ago. For details about the big new features in this release, we as usual recommend to read LWN.net articles covering the merge window: part 1, part 2 and part 3.

According to the KPS statistics, there were 12128 commits in this release, and with 110 patches, Bootlin is the 20th contributing company. As usual, we did some contributions to this release, though a somewhat smaller number than for previous releases.

Our main contributions this time around:

On the support for Atmel ARM SoCs
- Alexandre Belloni contributed a fairly significant number of cleanups: description of the slow clock in the Device Tree, removal of left-over from platform-data usage in device drivers (no longer needed now that all Atmel ARM platforms use the Device Tree).
- Boris Brezillon contributed numerous improvements to the atmel-hlcdc, which is the DRM/KMS driver for the modern Atmel ARM SoCs. He added support for several SoCs to the driver (SAMA5D2, SAMA5D4, SAM9x5 and SAM9n12), added PRIME support, and support for the RGB565 and RGB444 output configurations.
- Maxime Ripard improved the dmaengine drivers for Atmel ARM SoCs (at_hdmac and at_xdmac) to add memset and scatter-gather memset capabilities.
On the support for Allwinner ARM SoCs
- Maxime Ripard converted the SID driver to the newly introduced nvmem framework. Maxime also did some minor pin-muxing and clock related updates.
- Boris Brezillon fixed some issues in the NAND controller driver.
On the support for Marvell EBU ARM SoCs
- Thomas Petazzoni added the initial support for suspend to RAM on Armada 38x platforms. The support is not fully enabled yet due to remaining stability issues, but most of the code is in place. Thomas also did some minor updates/fixes to the XOR and crypto drivers.
- Grégory Clement added the initial support for standby, a mode that allows to forcefully put the CPUs in deep-idle mode. For now, it is not different from what cpuidle provides, but in the future, we will progressively enable this mode to shutdown PHY and SERDES lanes to save more power.
On the RTC subsystem, Alexandre Belloni did numerous fixes and cleanups to the rx8025 driver, and also a few to the at91sam9 and at91rm9200 drivers.
On the common clock framework, Boris Brezillon contributed a change to the ->determinate_rate() operation to fix overflow issues.
On the PWM subsystem, Boris Brezillon contributed a number of small improvements/cleanups to the subsystem and some drivers: addition of a pwm_is_enabled() helper, migrate drivers to use the existing helper functions when possible, etc.

The detailed list of our contributions is: