SAM9X60-EK Evaluation Kit - Fast Boot Demonstration
Contents
Introduction
Booting an embedded Linux® system quickly is crucial for time-critical applications and significantly improves the user experience. This training topic gives some essential tips and techniques to achieve a quick boot on Microchip microprocessors (MPUs).
In this training, you will learn how to launch an Ensemble Graphics Toolkit (EGT) GUI-based application on a Microchip MPU running Linux in under 3 seconds.
Summary of Steps
- Minimize Boot Time
- Minimize Linux Kernel Load and Startup Time
- Minimize Application Startup Time
- Prepare SD Memory Card
- Fast Boot EGT Application from SD Memory Card
Prerequisites
- Introduction to SAM9X60-EK Evaluation Kit
- Knowledge of the general Boot process
- SAM9X60 Boot Process
- SAM9X60 Data Sheet (Section 11 – Boot Strategies)
- Attaching the TM5000 WVGA Display to the SAM9X60-EK
- Ensemble Graphics Toolkit
- A working cross-toolchain for Arm®-based MPU target is required to complete this topic.
- You can set one up in the topic: EGT - Preparing the Host PC and Target
Hardware
You will use the SAM9X60-EK Evaluation Kit and a TM5000 High-Performance WVGA Display Module with maXTouch® Technology.
Refer to "SAM9X60-EK - Attaching the TM5000 WVGA Display" for instructions on how to assemble the LCD display onto the SAM9X60-EK.
Minimize Boot Time
In this section, you will download, configure, and build the second-stage bootloader, at91bootstrap, for fast booting.
Create project directory:
Name your project directory fastboot.
Download at91bootstrap from the linux4sam remote repository in GitHub:
$ git clone git://github.com/linux4sam/at91bootstrap.git
Configure using sam9x60eksd_linux_image_dt_defconfig:
Once you have cloned at91bootstrap to your project directory, you can configure the build. In this step, you will use a default configuration file, sam9x60eksd_linux_image_dt_defconfig, located in the ~/fastboot/at91bootstrap/board/ directory. This will configure the at91bootstrap (second-stage bootloader) to load the Linux kernel directly, thereby eliminating U-Boot (third-stage bootloader) from the boot sequence.
Change the directory to the ~/fastboot/at91bootstrap folder and begin the configuration process:
$ make sam9x60eksd_linux_image_dt_defconfig
Customize the at91bootstrap configuration to minimize boot time.
To customize the default configuration settings, use menuconfig. Menuconfig allows you to view the default configuration and make the required changes.
Highlight Image Loading Strategy and observe that Support loading Linux directly has been selected.
De-select Display banner option by pressing <N>. Select <Exit>.
Highlight Select slow clock configuration profile and change the setting to Use Internal RC oscillator as a source of slow clock.
Switching the slow clock source to the internal oscillator will eliminate the settling time required by the external crystal (which is selected by default). This will reduce boot time by almost one second.
Build at91bootstrap.
Now that you have made all the configuration changes to reduce boot time, you can build at91bootstrap.
The resulting binary images will be found in the at91bootstrap/binaries directory. The at91bootstrap.bin image will be used in a later section.
Minimizing Linux Kernel Load and Startup Time
The Linux kernel load and startup time can be drastically reduced by configuring only the necessary peripherals and subsystems required by the Ensemble Graphics Toolkit (EGT) application. Therefore, from the SAM9X60 default device tree, you will disable all the peripherals that are not used by the EGT application. You will also disable them from the kernel configuration. The fewer subsystems and drivers the Kernel must initialize, the faster it will boot. Finally, you will add support for the LCD display.
Get linux-at91.
Download linux-at91 from the Microchip GitHub repository.
$ git clone https://github.com/linux4sam/linux-at91.git -b linux4sam-2020.04
Open device tree file and disable all unused peripherals.
To make changes to the device tree, open the at91-sam9x60-ek.dts file using a text editor of your choice.
$ vi at91-sam9x60ek.dts
Now you can edit the *.dts file.
Add the following bold line:
model = "Microchip SAM9X60-EK";
compatible = "microchip,sam9x60ek",
"microchip,sam9x60", "atmel,at91sam9";
. . .
. . .
chosen {
**bootargs="root=/dev/mmcblk0p2 rw rootwait loglevel=0";**
stdout-path = "serial0:115200n8";
};
The loglevel is set to 0 which indicates minimal kernel debug messages and only the ones with utmost priority.
Change the status from “okay” to “disable” for the following peripherals: adc, can0, can1, classd, dbgu, flx4, flx5, flx6, i2s, macb0, pwm0, sdmmc1, qspi, usb0, usb1, usb2, isi.
vddana-supply = <&vdd1_3v3>;
vref-supply = <&vdd1_3v3>;
pinctrl-names = "default";
pinctrl-0 =
<&pinctrl_adc_default &pinctrl_adtrg_default>;
status = "disabled";
};
. . .
. . .
&can0 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_can0_rx_tx>;
status = "disabled"; /* Conflict with dbgu. */
};
&can1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_can1_rx_tx>;
status = "disabled";
};
&classd {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_classd_default>;
atmel,pwm-type = "diff";
atmel,non-overlap-time = <10>;
status = "disabled";
};
. . .
. . .
&flx5 {
atmel,flexcom-mode = <atmel_flexcom_mode_usart>;
status = "disabled";
. . .
. . .
&flx6 {
atmel,flexcom-mode = <atmel_flexcom_mode_twi>;
status = “disabled”;
. . .
. . .
&macb0 {
phy-mode = "rmii";
#address-cells = <1>;
#size-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_macb0_rmii>;
status = "disabled";
. . .
. . .
&sdmmc1 {
bus-width = <4>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sdmmc1_default>;
no-1-8-v;
non-removable;
status = "disabled"; /* Conflict with flx4. */
};
&qspi {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_qspi>;
status = "disabled"; /* Conflict with i2s. */
. . .
. . .
&usb0 {
atmel,vbus-gpio = <&pioB 16 GPIO_ACTIVE_HIGH>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_usba_vbus>;
status = "disabled";
};
&usb1 {
num-ports = <3>;
atmel,vbus-gpio = <0
&pioD 15 GPIO_ACTIVE_HIGH
&pioD 16 GPIO_ACTIVE_HIGH>;
status = "disabled";
};
&usb2 {
status = "disabled";
};
. . .
. . .
&watchdog {
status = "okay";
}; /*End of at91-sam9x60ek.dts file*/
Add support for the pda5 display in the device tree file at the end.
status = "okay";
};
/* Support for pda5 */
&i2c0 {
dmas = <0>, <0>;
#address-cells = <1>;
#size-cells = <0>;
qt1070: keyboard@1b {
compatible = "qt1070";
reg = <0x1b>;
interrupt-parent = <&pioB>;
interrupts = <17 0x0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_qt1070_irq>;
};
mxt: atmel_mxt_ts@4a {
compatible = "atmel,atmel_mxt_ts";
reg = <0x4a>;
interrupt-parent = <&pioC>;
interrupts = <25 0x8>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_mxt_irq>;
wakeup-source;
};
};
&hlcdc {
status = "okay";
hlcdc-display-controller {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb888>;
port@0 {
#address-cells = <1>;
#size-cells = <0>;
hlcdc_panel_output: endpoint@0 {
reg = <0>;
remote-endpoint = <&panel_input>;
};
};
};
hlcdc_pwm: hlcdc-pwm {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lcd_pwm>;
};
};
&gpu {
status = "okay";
};
&pinctrl {
qt1070 {
pinctrl_qt1070_irq: qt1070_irq {
atmel,pins = <at91_piob 17="" at91_periph_gpio="" at91_pinctrl_pull_up_deglitch="">;
};
};
mxt {
pinctrl_mxt_irq: mxt_irq {
atmel,pins = <at91_pioc 25="" at91_periph_gpio="" at91_pinctrl_pull_up_deglitch="">;
};
};
lcd {
pinctrl_lcd_base: lcd-base-0 {
atmel,pins = <at91_pioc 27="" at91_periph_a="" at91_pinctrl_none="" *="" lcdvsync="" at91_pioc="" 28="" lcdhsync="" 24="" lcddisp="" 29="" lcdden="" 30="">; /* LCDPCK */
};
pinctrl_lcd_rgb888: lcd-rgb-3 {
atmel,pins = <at91_pioc 0="" at91_periph_a="" at91_pinctrl_none="" *="" lcdd0="" pin="" at91_pioc="" 1="" lcdd1="" 2="" lcdd2="" 3="" lcdd3="" 4="" lcdd4="" 5="" lcdd5="" 6="" lcdd6="" 7="" lcdd7="" 8="" lcdd8="" 9="" lcdd9="" 10="" lcdd10="" 11="" lcdd11="" 12="" lcdd12="" 13="" lcdd13="" 14="" lcdd14="" 15="" lcdd15="" 16="" lcdd16="" 17="" lcdd17="" 18="" lcdd18="" 19="" lcdd19="" 20="" lcdd20="" 21="" lcdd21="" 22="" lcdd22="" 23="">; /* LCDD23 pin */
};
pinctrl_lcd_pwm: lcd_pwm {
atmel,pins = <at91_pioc 26="" at91_periph_a="" at91_pinctrl_none="">;
};
};
};
&{/} {
model = "Microchip SAM9X60-EK TM5000";
backlight: backlight {
compatible = "pwm-backlight";
pwms = <&hlcdc_pwm 0 50000 0>;
brightness-levels = <0 4 8 16 32 64 128 255>;
default-brightness-level = <0>;
power-supply = <&bl_reg>;
status = "okay";
};
bl_reg: backlight_regulator {
compatible = "regulator-fixed";
regulator-name = "backlight-power-supply";
regulator-min-microvolt = <5000000>;
regulator-max-microvolt = <5000000>;
status = "okay";
};
panel: panel {
compatible = "pda,91-00156-a0", "simple-panel";
backlight = <&backlight>;
power-supply = <&panel_reg>;
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
port@0 {
reg = <0>;
#address-cells = <1>;
#size-cells = <0>;
panel_input: endpoint@0 {
reg = <0>;
remote-endpoint = <&hlcdc_panel_output>;
};
};
};
panel_reg: panel_regulator {
compatible = "regulator-fixed";
regulator-name = "panel-power-supply";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
status = "okay";
};
};
&isi {
status = "disabled";
};
/* End of pda5 support */
/* End of at91-sam9x60ek.dts file */
Disable peripherals from the kernel configuration.
Make the following changes to the kernel configurations by running menuconfig.
$ make at91_dt_defconfig ARCH=arm
$ make menuconfig
Navigate to Networking Support and de-select it by pressing <N>.
Navigate to each of the following unused peripherals and exclude them by pressing <N>.
- Memory Technology device (MTD) support
- Block devices
- SCSI Device support
- SPI support
- PPS support
- Hardware Monitoring support
- Multimedia support
- Sound card support
- USB support
- Staging drivers
- Industrial I/O support
Build linux-at91.
Run the make command along with ARCH and CROSS_COMPILE variables.
$ make ARCH=arm CROSS_COMPILE=<path_to>/<cross_compiler>
The resulting device tree image is linux-at91/arch/arm/boot/dts/at91-sam9x60ek.dtb and the kernel image is linux-at91/arch/arm/boot/zImage.
Minimize Application Startup Time
The Linux kernel loads an init script that loads other services and applications. To minimize boot time, you will replace the standard init script with a minimal script.
The minimal script performs the following:
- Mounts /sysfs, which is needed to control the backlight brightness from within the application.
- Loads the final application, which is a basic automotive dashboard graphical display developed using the Ensemble Graphics Toolkit (EGT).
The application is compiled as a static executable. All the images, logos, and resources are compiled directly into the application and statically linked to it. Therefore, the resources are immediately available and mapped into the application’s address space.
Create Custom init script.
Create an init file and open using a text editor of your choice.
$ vi init
Copy the following lines.
mount -t sysfs none /sys
/usr/bin/egt_dashboard_fastboot
exec /bin/sh
Change the init script to executable.
$ chmod +x init
Download Ensemble Graphics Toolkit (EGT) application.
Download the EGT application, egt_dashboard_fastboot, to your ~/fastboot directory and change the image to an executable.
$ chmod +x egt_dashboard_fastboot
You will be copying the executable init and egt_dashboard_fastboot files to the Root File System (RootFS) of final image.
Preparing SD Memory Card Image
In this section, you will download a demonstration image from the Linux4SAM website for the purpose of using the Root File System on the image. You will flash the image to an SD Memory Card and delete the files in the BOOT partition. Finally, you will copy the at91bootstrap.bin, at91-sam9x60ek.dtb, and zImage files that you created in the previous section.
Download the SAM9X60-EK demonstration image from the Linux4SAM website.
The latest demonstration images for the SAM9X60-EK are available on the Linux4SAM website.
There you will find three sets of images created from one of three Build Systems:
- The Yocto Project
- Buildroot
- OpenWRT
Choose the Buildroot based demo image with graphics support: linux4sam-buildroot-sam9x60ek-graphics-X.Y.img.bz2 where X.Y is the version number (X is the year and Y is the month of release).
Delete the files in the BOOT(FAT32) partition.
Write binary files, which were created in the previous sections to the BOOT partition of the SD memory card.
Copy the at91bootrap.bin file.
$ cp at91bootstrap.bin /media/<username>/<partion_name>/boot.bin
Copy the at91-sam9x60ek.dtb and zImage files.
$ cp at91-sam9x60ek.dtb /media/<username>/<partion_name>/at91-sam9x60ek.dtb
$ cp zImage /media/<username>/<partion_name>/zImage
Now you have an SD Memory Card with the bootloader image (boot.bin), Linux kernel device tree (at91-sam9x60ek.dtb), and the kernel (zImage) in the BOOT partition. You also have the Root File System in the ROOTFS partition of the SD card.
Copy init and egt_dashboard_fastboot images to the RootFS partition of SD card.
$ sudo cp –p init /media/<username>/ROOTFS/sbin/init
$ sudo cp egt_dashboard_fastboot /media/<username>/ROOTFS/usr/bin/
Remove the SD Memory Card from the Linux computer. You have now created a bootable Linux system image on the SD Memory Card.
Note that there are no u-boot images on the SD Memory Card. Recall that you configured and built at91bootstrap to load the Linux kernel directly. This will reduce boot time.
Fast Boot from SD Memory Card
The SAM9X60-EK can be powered by one of two methods:
- J1: An external power jack to supply +5 VDC via a 2.1 mm center-positive plug
- J7: Powered through the USB Micro-B connector USB port A
Insert the SD card to slot J4 on the SAM9X60-EK target board.
Press the RESET push button SW3 (nRST).
Congratulations! You have reduced the boot time of an embedded Linux system with an Ensemble Graphics Toolkit (EGT) application up and running!
Summary
In this training, you changed the standard Linux boot process on the Microchip Microprocessors to reduce the boot time.
- You configured and built at91bootstrap to load the Linux kernel directly.
- You removed all subsystems and kernel drivers that are not used by the final application.
- You used a pre-built RootFS on the SD card and replaced the standard init script with a minimal script that just loads the sysfs and EGT application.
- The final application is an EGT Dashboard graphical demo on a Microchip PDA5 touchscreen.
The result is a fast boot of the EGT application in less than three seconds on cold reset!
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