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Linux® Kernel - 4.9

Last modified by Microchip on 2026/01/09 08:12

Linux 4.9 for AT91 source code

The Linux® kernel for Microchip Arm®-based PMUs (aka AT91) is distributed as a GIT tree hosted on GitHub® as a fork of the official Linus Torvalds' git tree. The objective of the Microchip Linux team is to integrate all the AT91-related material in the official Linux Kernel.
Before completing this inclusion process, which can take time, this website provides the Linux4SAM Linux Kernel git tree for AT91 devices at:

https://github.com/linux4sam/linux-at91/tree/linux-4.9-at91

Tags

linux4sam_5.8 tag

Enhancements are added on top of the official v4.9 Linux kernel tag where most of the Microchip SoC features are already supported. Note as well that we re-integrate each and every stable kernel release on top of this Long Term Support (LTS) kernel revision. This means that each v4.9.x version is merged in our branch.

Here is a little summary of the main additional enhancements:

  • Integration of stable kernel updates up to v4.9.87
  • Addition of the Peripheral Touch Controller (PTC) input driver with firmware and configuration files management
  • Addition of the new SAMA5D2 PTC EK board
  • Use of bounce buffer with SPI on ARM9 SoCs
  • fix SMC register offset for SAMA5D2
  • fix 10/100 Ethernet macb settings for SAMA5D3 by removing support for scatter-gather

linux4sam_5.7 tag

  • Integration of stable kernel updates up to v4.9.52
  • Support for low-power Backup+Self-Refresh mode for SAMA5D2 and the SAMA5D2 Xplained board
  • SAMA5D2: most of the driver converted to support the Backup+Self-Refresh mode
  • Low power modes: use of kernel command line parameters to choose the Power Management scheme (ULP0, ULP1, Backup+Self-Refresh)
  • Addition of the new SAMA5D27 SOM1 EK board containing the SAMA5D27 SiP
  • SAMA5D4: addition of the G1 Video Decoder (Vdec) drivers
  • Kernel configuration: Use of the High resolution timers option by default
  • Kernel configuration: Use of the tick-less system configuration by default
  • Kernel configuration: Use of CONFIG_JUMP_LABEL for improving network performance
  • SAMA5D2: ADC add hardware trigger and buffer support
  • SAMA5D2: ISC: format configuration enhancement
  • Addition of another camera sensor: the ov7670
  • Addition of several peripherals in device tree: CAN, PWM for instance
  • fixes: SAMA5D4-compatible watchdog, SAMAD2 LCD drive strength on base signals, use of CPU I/O for SAM9 SPI controller, USB host vbus on SAMA5D2

linux4sam_5.6 tag

  • Integration of stable kernel updates up to v4.9.30
  • SAMA5D2: QSPI: enhancement with 4-bit addressing and Serial Flash Discoverable Parameters (SFDP) tables
  • SAMA5D2: CAN driver support for latest CAN_FD IP enhancements
  • SAMA5D2: Ultra Low-Power mode ULP1 support
  • SAMA5D2: PWM driver
  • SAMA5D2: Audio PLL and ClassD audio amplifier drivers
  • SAMA5D2: I2S driver
  • pinctrl driver: add support for OUTPUT config
  • PWM: switch to atomic PWM
  • Hardware Crypto accelerators: SHA and AES: add support to hmac(shaX) and authenc(hmac(shaX), Y(aes)) modes
  • ISI and ISC with camera sensors are now all compatible with the V4L2 API
  • maXTouch® driver: stabilize and integrate driver enhancements from atmel-maxtouch github repository
  • fixes: cpuIDLE, serial driver with DMA

Getting Kernel sources

To get the source code, you have to clone the repository:

$ git clone git://github.com/linux4sam/linux-at91.git
Cloning into 'linux-at91'...
remote: Counting objects: 4524288, done.
remote: Compressing objects: 100% (721/721), done.
remote: Total 4524288 (delta 385), reused 1 (delta 1), pack-reused 4523564
Receiving objects: 100% (4524288/4524288), 1.22 GiB | 1.35 MiB/s, done.
Resolving deltas: 100% (3777338/3777338), done.
Checking connectivity... done.
Checking out files: 100% (49565/49565), done.

The source code has been taken from the master branch which is pointing on the latest branch we use.

hand Note that you can also add this Linux4SAM repository as a remote GIT repository to your usual Linux git tree. It will save you a lot of bandwidth and download time:

$ git remote add linux4sam git://github.com/linux4sam/linux-at91.git
$ git remote update linux4sam
Fetching linux4sam
From git://github.com/linux4sam/linux-at91
 * [new branch]                linux-2.6.39-at91 -> linux4sam/linux-2.6.39-at91
* [new branch]                linux-3.10-at91 -> linux4sam/linux-3.10-at91
* [new branch]                linux-3.15-at91 -> linux4sam/linux-3.15-at91
* [new branch]                linux-3.18-at91 -> linux4sam/linux-3.18-at91
* [new branch]                linux-3.4.9-at91 -> linux4sam/linux-3.4.9-at91
* [new branch]                linux-3.6.9-at91 -> linux4sam/linux-3.6.9-at91
* [new branch]                linux-4.1-at91 -> linux4sam/linux-4.1-at91
* [new branch]                linux-4.4-at91 -> linux4sam/linux-4.4-at91
* [new branch]                linux-4.9-at91 -> linux4sam/linux-4.9-at91
* [new branch]                master     -> linux4sam/master

If you want to use an other branch, you can list them and use one of them by doing this:

$ git branch -r
  origin/HEAD -> origin/master
  origin/linux-2.6.39-at91
  origin/linux-3.10-at91
  origin/linux-3.15-at91
  origin/linux-3.18-at91
  origin/linux-3.4.9-at91
  origin/linux-3.6.9-at91
  origin/linux-4.1-at91
  origin/linux-4.4-at91
  origin/linux-4.9-at91
  origin/master
$ git checkout origin/linux-4.9-at91 -b linux-4.9-at91
Branch linux-4.9-at91 set up to track remote branch linux-4.9-at91 from origin.
Switched to a new branch 'linux-4.9-at91'

Configure and Build the Linux kernel

Now you have to configure the Linux kernel according to your hardware. We have two default configuration at91 SoC in arch/arm/configs

arch/arm/configs/at91_dt_defconfig
arch/arm/configs/sama5_defconfig
  • at91_dt_defconfig: for at91sam ARM926 series chips
  • sama5_defconfig: for SAMA5 series chips

Now we Configure and Build kernel for board:

$ make ARCH=arm sama5_defconfig
  HOSTCC  scripts/basic/fixdep
  HOSTCC  scripts/kconfig/conf.o
  SHIPPED scripts/kconfig/zconf.tab.c
  SHIPPED scripts/kconfig/zconf.lex.c
  SHIPPED scripts/kconfig/zconf.hash.c
  HOSTCC  scripts/kconfig/zconf.tab.o
  HOSTLD  scripts/kconfig/conf
#
# configuration written to .config
#

At this step, you can modify default configuration using the menuconfig

$ make ARCH=arm menuconfig

And build the Linux kernel image, before you build you need set up the cross compile toolchain, check this section.(This link points to a non-existent section)

$ make ARCH=arm [..] Kernel: arch/arm/boot/Image is ready Kernel: arch/arm/boot/zImage is ready

Now you have an usable compressed kernel image zImage.

If you need an uImage you can run this additional step:

make ARCH=arm uImage LOADADDR=0x20008000

[..]

  Kernel: arch/arm/boot/zImage is ready
  UIMAGE  arch/arm/boot/uImage
Image Name:   Linux-4.1.0-linux4sam_5.3+
Created:      Fri Sep  9 17:02:45 2016
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3441072 Bytes = 3360.42 kB = 3.28 MB
Load Address: 20008000
Entry Point:  20008000
  Image arch/arm/boot/uImage is ready


make ARCH=arm dtbs

[..]
  DTC     arch/arm/boot/dts/at91-kizbox2.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_ptc.dtb
  DTC     arch/arm/boot/dts/at91-sama5d27_som1_ek.dtb
  DTC     arch/arm/boot/dts/at91-sama5d27_som1_ek_pda4.dtb
  DTC     arch/arm/boot/dts/at91-sama5d27_som1_ek_pda7.dtb
  DTC     arch/arm/boot/dts/at91-sama5d27_som1_ek_pda7b.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained_pda4.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained_pda7.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained_pda7b.dtb
  DTC     arch/arm/boot/dts/at91-sama5d3_xplained.dtb
  DTC     arch/arm/boot/dts/at91-sama5d3_xplained_pda4.dtb
  DTC     arch/arm/boot/dts/at91-sama5d3_xplained_pda7.dtb
  DTC     arch/arm/boot/dts/at91-sama5d3_xplained_pda7b.dtb
  DTC     arch/arm/boot/dts/sama5d31ek.dtb
  DTC     arch/arm/boot/dts/sama5d33ek.dtb
  DTC     arch/arm/boot/dts/sama5d34ek.dtb
  DTC     arch/arm/boot/dts/sama5d35ek.dtb
  DTC     arch/arm/boot/dts/sama5d36ek.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_cmp.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_ma5d4evk.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_xplained.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_xplained_pda4.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_xplained_hdmi.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_xplained_pda7.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4ek.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4_xplained_pda7b.dtb
  DTC     arch/arm/boot/dts/at91-sama5d4ek_isi.dtb
  DTC     arch/arm/boot/dts/at91-vinco.dtb
[..]

If the building process is successful, the final images can be found under arch/arm/boot/ directory.

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