Linux Kernel - 4.14

Linux 4.14 for AT91 source code

The Linux kernel for Microchip ARM-Based MPUs (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-4.14-at91

Tags

linux4sam_6.0 tag

Enhancements are added on top of the official v4.14 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 v4.14.x version is merged in our branch.

Here is a little summary of the main additional enhancements:

• Integration of stable kernel updates up to v4.14.73
• Support for PDA 5" screen as the default display
• Added video decoder driver for SAMA5D4
• Added multidrop support for serial controllers
• Added ISO 7816 driver
• Ethernet - retrieve MAC address from provided NVMEM
• Ethernet hardware RX queues , RX hardware filtering, queue statistics
• PHY-handle device tree support
• Ethernet padding and FCS enhancement
• Ethernet re-factor power management suspend/resume
• Power management support for backup and self-refresh: QSPI, FLEXCOM, TCB-PWM, programmable clocks.
• Updated SPI-NOR non uniform erase support
• Added USART SPI driver
• ADC DMA support on SAMA5D2
• ADC resistive touch screen support for SAMA5D2
• Mikroelectronika audio codec board driver
• Rework I2S clock driver on SAMA5D2
• fixes: Ethernet TX DMA descriptors processing, shutdown controller register corruption while shutting down.

Getting Kernel sources

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

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:

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

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

• 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

Now, in the menuconfig dialog, you can easily add or remove some features. Once done, Move to <Exit> with arrows and press this button hitting the Enter key to exit from this screen.

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-nattis-2-natte-2.dtb
  DTC     arch/arm/boot/dts/at91-sama5d27_som1_ek.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_ptc_ek.dtb
  DTC     arch/arm/boot/dts/at91-sama5d2_xplained.dtb
  DTC     arch/arm/boot/dts/at91-sama5d3_xplained.dtb
  DTC     arch/arm/boot/dts/at91-tse850-3.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-sama5d4ek.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.

Recent FAQ

• Using Max Touch
• Crypto hardware acceleration
• USB Gadget Configuration
• How to use Pulse Width Modulation driver
• External Component on External Bus Interface
• How to use the Atmel KMS/DRM LCD driver
• Using the SAMA5D2-compatible Resistive Touchscreen
• Use of the AT91 ADC driver
• Using PTC (Peripheral Touch Controller)
• Using ISC (Image Sensor Controller)
• Use the Wakeup Feature of the Shutdown Controller.
• How to use record audio stream with PDMIC