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Linux® Kernel - 4.1

Last modified by Microchip on 2026/09/21 15:06

Linux 4.1 for AT91 source code

The Linux® kernel for Atmel | SMART processor-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 Atmel 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-4.1-at91

Tags

linux4sam_5.3 tag

  • add the drm bridge driver for HDMI encoder silicon image: sii902x that is present on SAMA5D4 Xplained board
  • several LCD enhancements:
    • extended timings rage for SAMA5D2 and SAMA5D4
    • optimize AHB master DMA interface by choosing the less used one for a particular overlay
    • add access to GEM for using overlay for video decoding via GStreamer®
  • QSPI: add support for FLASH >16MiB : 4byte address mode
  • QSPI: add support for Macronix® mx25l25635e that is present on sama5d2 Xplained board
  • fixes for QSPI, PMIC drivers
  • Regulator/SDHCI: strengthen support for SD card insertion/removal

linux4sam_5.2 tag

  • SAMA5D4 Demo updated together with the other Xplained board demos
  • SAMA5D4 Video Decoder driver
  • Move to the Ultra-Low-Power mode ULP1 for suspend/resume power management
    • for more information on this mode, read chapter "62.5.3: Ultra Low-Power (ULP) Mode" and the corresponding table "Table 62.5 Low-power Mode Configuration Summary"
    • suspend/resume ULP1 mode wake-up sources are wakeup button and RTC
    • gain better consumption numbers due to the stop of most of the clocks while entering this mode
    • fast resume time
  • WIFI WILC1000 driver integrated from the latest source code submitted to the Linux Mainline staging directory

linux4sam_5.1 tag

  • Addition of PDA inc 4.3" and 7" screens: TM430x and TM7000/7000B
  • New Pulse Density Modulation Interface Controller (PDMIC) for SAMA5D2 PDM microphone interface
  • New SAMA5D2 ADC driver: using the IIO sub-system, software trigger supported
  • fixes for: QSPI, XDMA, RTC for suspend/resume, phy interface for suspend/resume, SHA driver

linux4sam_5.0 tag

As a updated kernel revision this branch contains all the enhancements already found on the the  Linux Kernel - 3.18.

Here is a little summary of the enhancements added on top of the official v4.1 Linux kernel tag:

  • all Atmel material included in the following 4.2 kernel:
    • addition of newer AT91 boards
    • AT91SAM9x5: pwm0 pinctrl definition
    • SAMA5D4: more peripherals: usarts, uarts, spi, pioD access
    • SAMA5D3: phy address for gmac
    • regulator additions for the SD/MMC
    • rtc node for AT91SAM9RL/AT91SAM9RL-EK
  • addition of the new SAMA5D2 SoC and associated SAMA5D2 Xplained board
  • DMA: interleaved, memset and scatter-gathered memset offload operations
  • flexcom: serial, I2C and SPI: new FIFO and DMA modes for SAMA5D2
  • SDHCI driver (SD/MMC) for SAMA5D2
  • ClassD audio output driver for SAMA5D2
  • Image Sensor:
    • ISC: support YUV sensor output ; support RGB output format
    • ISI enhancement: add RGB565, GREY, SGRBG, SBGGR (Bayer) support
  • new shutdown controller driver for SAMA5D2
  • new I2S controller driver for audio on SAMA5D2
  • CAN controller for SAMA5D2
  • new watchdog driver for SAMA5D4 & SAMA5D2 SoCs
  • generated and audio PLL clocks for SAMA5D2
  • support for act8865 PMIC
  • LCD specification to the at91sam9x5 series and associated boards
  • fixes for USB, AES DMA configuration

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: 5239592, done.
remote: Compressing objects: 100% (764014/764014), done.
Receiving objects: 100% (5239592/5239592), 1018.56 MiB | 11.18 MiB/s, done.
remote: Total 5239592 (delta 4448248), reused 5218219 (delta 4427054)
Resolving deltas: 100% (4448248/4448248), done.
Checking out files: 100% (38567/38567), done.

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

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]                master     -> linux4sam/master

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

Set up ARM Cross Compiler

  • Ubuntu:
    In Ubuntu, you can install the ARM Cross Compiler by doing:
sudo apt-get install gcc-arm-linux-gnueabi
export CROSS_COMPILE=arm-linux-gnueabi-
  • Others:
    For others, you can download the Linaro cross compiler and set up the environment by doing:
wget -c https://releases.linaro.org/components/toolchain/binaries/4.9-2017.01/arm-linux-gnueabi/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi.tar.xz
tar xf gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi.tar.xz
export CROSS_COMPILE=`pwd`/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi/bin/arm-linux-gnueabi-

Configure and Build the Linux kernel

Now you have to configure the Linux kernel according to your hardware. We have two default configurations for the 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 a kernel for the 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 the default configuration using the menuconfig

$ make ARCH=arm menuconfig

And build the Linux kernel image. Before you build, you need to set up the cross-compile toolchain. Check this section.

$ make ARCH=arm

[..]

  Kernel: arch/arm/boot/Image is ready
  Kernel: arch/arm/boot/zImage is ready

Now you have a usable compressed kernel image zImage.

If you need a uImage, you can run this additional step:

make ARCH=arm uImage

[..]

  OBJCOPY arch/arm/boot/zImage
  Kernel: arch/arm/boot/zImage is ready
  UIMAGE  arch/arm/boot/uImage
Image Name:   Linux-4.1.0
Created:      Wed May  6 15:44:56 2015
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3537576 Bytes = 3454.66 kB = 3.37 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_xplained.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained_pda4.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/sama5d31ek.dtb
  DTC     arch/arm/boot/dts/sama5d31ek_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d31ek_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d31ek_revc_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d31ek_revc_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d31ek_revc.dtb
  DTC     arch/arm/boot/dts/sama5d33ek.dtb
  DTC     arch/arm/boot/dts/sama5d33ek_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d33ek_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d33ek_revc.dtb
  DTC     arch/arm/boot/dts/sama5d33ek_revc_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d33ek_revc_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d34ek.dtb
  DTC     arch/arm/boot/dts/sama5d34ek_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d34ek_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d34ek_revc.dtb
  DTC     arch/arm/boot/dts/sama5d34ek_revc_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d34ek_revc_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d35ek.dtb
  DTC     arch/arm/boot/dts/sama5d35ek_revc.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d36ek.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_pda7.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_revc.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_revc_pda4.dtb
  DTC     arch/arm/boot/dts/sama5d36ek_revc_pda7.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

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

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