Kernel-with-device-tree - Revision history

JulienB: info already elsewhere

2020-09-16T08:20:15Z

info already elsewhere

← Older revision		Revision as of 10:20, 16 September 2020
Line 106:		Line 106:
	<pre class="apf">		<pre class="apf">
	BIOS> setenv consoledev ttymxc0		BIOS> setenv consoledev ttymxc0
	BIOS> setenv fdt_addr_r a1000000 ~~(with the apf27 - 41000000 with an apf28 - 91000000 with an apf51 )~~		BIOS> setenv fdt_addr_r a1000000
	BIOS> saveenv		BIOS> saveenv
	BIOS> run update_kernel		BIOS> run update_kernel

JulienB: /* Background */

2020-09-16T08:17:26Z

Background

← Older revision		Revision as of 10:17, 16 September 2020
Line 1:		Line 1:
	=Background=		=Background=

	The idea behind device tree is quite simple. When the kernel starts, it needs to initialize the drivers for the devices on the board. But often on embedded systems, devices can't be discover at running time. In this case, the Linux kernel has a c file that ~~initialize~~ the devices for the board. So the kernel must be modified/compiled for each board.		The idea behind device tree is quite simple. When the kernel starts, it needs to initialize the drivers for the devices on the board. But often on embedded systems, devices can't be discover at running time. In this case, the Linux kernel has a C "machine" file that initializes/describes the devices for the board. So the kernel must be modified/compiled for each board.

	Another way is to provide a small file that ~~describe~~ the board to the Linux kernel. When the kernel start, it reads this file (called dtb for Device Tree Binary) to know the devices on the board, and ~~initialize~~ useful drivers.		Another way is to provide a small file that describes the board to the Linux kernel. When the kernel start, it reads this file (called dtb for Device Tree Binary) to know the devices on the board, and initializes useful drivers.

	Some informations on device tree may be found here:		Some informations on device tree may be found here:

JulienB at 14:19, 19 January 2018

2018-01-19T14:19:06Z

@@ Line 138: / Line 138: @@
 BIOS> setenv fdt_addr_r
 BIOS> saveenv
 </pre>

JulienB at 14:12, 19 January 2018

2018-01-19T14:12:42Z

← Older revision		Revision as of 16:12, 19 January 2018
Line 3:		Line 3:
	The idea behind device tree is quite simple. When the kernel starts, it needs to initialize the drivers for the devices on the board. But often on embedded systems, devices can't be discover at running time. In this case, the Linux kernel has a c file that initialize the devices for the board. So the kernel must be modified/compiled for each board.		The idea behind device tree is quite simple. When the kernel starts, it needs to initialize the drivers for the devices on the board. But often on embedded systems, devices can't be discover at running time. In this case, the Linux kernel has a c file that initialize the devices for the board. So the kernel must be modified/compiled for each board.

	Another way is to provide a small file that describe the board to the Linux kernel. When the kernel start, it reads this file (called dtb for Device Tree Binary) to know the devices on the board, and initialize ~~usefull~~ drivers.		Another way is to provide a small file that describe the board to the Linux kernel. When the kernel start, it reads this file (called dtb for Device Tree Binary) to know the devices on the board, and initialize useful drivers.

	Some ~~information~~ on device tree may be found here:		Some informations on device tree may be found here:
	* http://elinux.org/Device_Trees		* http://elinux.org/Device_Trees
	* http://devicetree.org/Main_Page		* http://devicetree.org/Main_Page
Line 13:		Line 13:
	=Compilation=		=Compilation=

	To use device tree on ~~arm~~, both bootloader (U-Boot) and kernel should be compiled with the support of device tree.		To use device tree on ARM platforms, both bootloader (U-Boot) and kernel (Linux) should be compiled with the support of device tree.

	==U-Boot==		==U-Boot==
Line 22:		Line 22:

	The 3.4+ kernels have already the Device Tree support for some ARM SoC.		The 3.4+ kernels have already the Device Tree support for some ARM SoC.
	* ~~imxl~~ (apf9328) : no		* i.mxl (apf9328) : no
	* ~~imx27~~ (apf27) : yes		* i.mx27 (apf27) : yes
	* ~~imx51~~ (apf51) : yes		* i.mx51 (apf51) : yes
	* ~~imx28~~ (~~apf28~~) : yes		* i.mx28 ([[APF28]]) : yes
	* ~~imx6~~ (~~apf6~~) : yes		* i.mx6 ([[APF6]]) : yes
			* i.mx6ul ([[OPOS6UL]]) : yes
	~~The Linux configuration file should have~~ (~~should be done by default~~):
	* CONFIG_MACH_IMX27_DT (on APF27)
	* CONFIG_MACH_IMX51_DT (on APF51)
	* CONFIG_MACH_MXS_DT (on APF28)
	* CONFIG_SERIAL_IMX
	* CONFIG_SERIAL_IMX_CONSOLE
	** CONFIG_SERIAL_MXS_AUART_CONSOLE=y (on 3.8 ??)

	Nothing else needs to be done, because the kernel image is build by the armadeus SDK with the "make" command.		Nothing else needs to be done, because the kernel image is build by the armadeus SDK with the "make" command.

	* Starting with 3.8+ kernels, multi arch support is activated for i.MX(1/2/3/5) processors and so loadaddr should be given at uImage build time:		* Starting with 3.8+ kernels, multi arch support is activated for i.MX(1/2/3/5) processors and so ''loadaddr'' should be given at ''uImage'' build time:
	<pre class="host">		<pre class="host">
	$ make linux LOADADDR=0xA0008000 (APF27)		$ make linux LOADADDR=0xA0008000 (APF27)
Line 59:		Line 52:
	A dtb (Device Tree Binary) file is created from a dts (Device Tree Source) file.		A dtb (Device Tree Binary) file is created from a dts (Device Tree Source) file.

	The 3.8+ kernel already have the support of device tree for ~~i.mx27 (~~[[~~APF27~~]]~~), i.mx28 ([[APF28]]) and i.mx51 ([[APF51]])~~.		The 3.8+ kernel already have the support of device tree for all Armadeus platforms except [[APF9328]].

	If your board hasn't a dts file, a ''<board>.dts'' must be added in the directory ''arch/arm/boot/dts/'' of the linux kernel.		If your board hasn't a dts file, a ''<board>.dts'' must be added in the directory ''arch/arm/boot/dts/'' of the linux kernel.
Line 96:		Line 89:

	==Boot Linux using U-Boot scripts==		==Boot Linux using U-Boot scripts==
	On the APF27, 28 and 51 with the latest U-Boot version things are even simpler:		On the APF27/28/51, [[APF6]] and [[OPOS6UL]] with the latest U-Boot version things are even simpler:
	* Device Tree can be loaded from the Flash memory		* Device Tree can be loaded from the Flash/eMMC memory
	* The variable fdt_addr_r defines the RAM address to load the DTB structure and will be used to notify the kernel of the DT location in RAM		* The variable fdt_addr_r defines the RAM address to load the DTB structure and will be used to notify the kernel of the DT location in RAM
	** APF27: Set the fdt_addr_r to A1000000		** APF27: Set the fdt_addr_r to A1000000
	** APF28: set the fdt_addr_r to 41000000		** APF28: set the fdt_addr_r to 41000000
	** APF51: set the fdt_addr_r to 91000000		** APF51: set the fdt_addr_r to 91000000
	** APF6: fdt_addr is set to 0x18000000 by default		** [[APF6]]: fdt_addr is set to 0x18000000 by default
			** [[OPOS6UL]]: fdt_addr is set to 0x88000000 by default
	* Some scripts are available to update the dtb partition:		* Some scripts are available to update the dtb partition:
	** ''download_dtb'' (download the dtb into the RAM from your local network)		** ''download_dtb'' (download the dtb into the RAM from your local network)

FabienM: /* Linux */

2016-02-10T14:25:34Z

Linux

← Older revision		Revision as of 16:25, 10 February 2016
Line 26:		Line 26:
	* imx51 (apf51) : yes		* imx51 (apf51) : yes
	* imx28 (apf28) : yes		* imx28 (apf28) : yes
			* imx6 (apf6) : yes

	The Linux configuration file should have (should be done by default):		The Linux configuration file should have (should be done by default):

FabienM: /* U-Boot */

2016-02-10T14:24:51Z

U-Boot

← Older revision		Revision as of 16:24, 10 February 2016
Line 16:		Line 16:

	==U-Boot==		==U-Boot==
	{{Note\|The APF27/U-boot 2012.04.01 patch 3.6, APF28/U-Boot 2012.04.01 patch 1.5 ~~and~~ APF51/U-Boot 2012.04.01 patch 1.5 are already configured to support device tree.}}		{{Note\|The APF27/U-boot 2012.04.01 patch 3.6, APF28/U-Boot 2012.04.01 patch 1.5, APF51/U-Boot 2012.04.01 patch 1.5 and APF6/All U-Boots are already configured to support device tree.}}
	* If you have an older U-Boot, instructions are kept [[Talk:Kernel-with-device-tree\|here]].		* If you have an older U-Boot, instructions are kept [[Talk:Kernel-with-device-tree\|here]].

FabienM: /* Boot Linux using U-Boot scripts */

2016-02-10T14:22:53Z

Boot Linux using U-Boot scripts

← Older revision		Revision as of 16:22, 10 February 2016
Line 101:		Line 101:
	** APF28: set the fdt_addr_r to 41000000		** APF28: set the fdt_addr_r to 41000000
	** APF51: set the fdt_addr_r to 91000000		** APF51: set the fdt_addr_r to 91000000
			** APF6: fdt_addr is set to 0x18000000 by default
	* Some scripts are available to update the dtb partition:		* Some scripts are available to update the dtb partition:
	** ''download_dtb'' (download the dtb into the RAM from your local network)		** ''download_dtb'' (download the dtb into the RAM from your local network)

FabienM: /* Boot Linux using U-Boot scripts */

2013-10-06T18:32:00Z

Boot Linux using U-Boot scripts

← Older revision		Revision as of 20:32, 6 October 2013
Line 98:		Line 98:
	* Device Tree can be loaded from the Flash memory		* Device Tree can be loaded from the Flash memory
	* The variable fdt_addr_r defines the RAM address to load the DTB structure and will be used to notify the kernel of the DT location in RAM		* The variable fdt_addr_r defines the RAM address to load the DTB structure and will be used to notify the kernel of the DT location in RAM
	* APF27: Set the fdt_addr_r to A1000000 - APF28: set the fdt_addr_r to 41000000 - APF51: set the fdt_addr_r to 91000000		** APF27: Set the fdt_addr_r to A1000000
			** APF28: set the fdt_addr_r to 41000000
			** APF51: set the fdt_addr_r to 91000000
	* Some scripts are available to update the dtb partition:		* Some scripts are available to update the dtb partition:
	** ''download_dtb'' (download the dtb into the RAM from your local network)		** ''download_dtb'' (download the dtb into the RAM from your local network)

FabienM: /* Linux */

2013-10-06T18:17:26Z

Linux

← Older revision		Revision as of 20:17, 6 October 2013
Line 33:		Line 33:
	* CONFIG_SERIAL_IMX		* CONFIG_SERIAL_IMX
	* CONFIG_SERIAL_IMX_CONSOLE		* CONFIG_SERIAL_IMX_CONSOLE
			** CONFIG_SERIAL_MXS_AUART_CONSOLE=y (on 3.8 ??)

	Nothing else needs to be done, because the kernel image is build by the armadeus SDK with the "make" command.		Nothing else needs to be done, because the kernel image is build by the armadeus SDK with the "make" command.

Jorasse: /* Boot Linux using U-Boot scripts */

2013-09-23T15:27:59Z

Boot Linux using U-Boot scripts

← Older revision		Revision as of 17:27, 23 September 2013
Line 99:		Line 99:
	* APF27: Set the fdt_addr_r to A1000000 - APF28: set the fdt_addr_r to 41000000 - APF51: set the fdt_addr_r to 91000000		* APF27: Set the fdt_addr_r to A1000000 - APF28: set the fdt_addr_r to 41000000 - APF51: set the fdt_addr_r to 91000000
	* Some scripts are available to update the dtb partition:		* Some scripts are available to update the dtb partition:
	** ''download_dtb'' (download the dtb into RAM from your local network)		** ''download_dtb'' (download the dtb into the RAM from your local network)
	** ''flash_dtb'' (~~tranfer~~ a dtb from RAM to flash)		** ''flash_dtb'' (transfer a dtb from RAM to flash)
	** ''update_dtb'' (download and flash a dtb)		** ''update_dtb'' (download and flash a dtb)
	* the boot scripts ''ubifsboot'', ''nfsboot'' and ''mmcboot'' support booting a kernel with a DT		* the boot scripts ''ubifsboot'', ''nfsboot'' and ''mmcboot'' support booting a kernel with a DT