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ARM: at91/Documentation: add a README for Atmel SoCs
Add a README file to describe Atmel SoCs (aka AT91) support in Mainline Linux:
- SoC list + datasheet web links
- Basic but useful information
- Device Tree conventions and Work In Progress statement.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Olof Johansson <olof@lixom.net>
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Documentation/arm/Atmel/README
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Documentation/arm/Atmel/README
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ARM Atmel SoCs (aka AT91)
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=========================
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Introduction
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------------
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This document gives useful information about the ARM Atmel SoCs that are
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currently supported in Linux Mainline (you know, the one on kernel.org).
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It is important to note that the Atmel | SMART ARM-based MPU product line is
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historically named "AT91" or "at91" throughout the Linux kernel development
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process even if this product prefix has completely disappeared from the
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official Atmel product name. Anyway, files, directories, git trees,
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git branches/tags and email subject always contain this "at91" sub-string.
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AT91 SoCs
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---------
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Documentation and detailled datasheet for each product are available on
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the Atmel website: http://www.atmel.com.
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Flavors:
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* ARM 920 based SoC
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- at91rm9200
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+ Datasheet
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http://www.atmel.com/Images/doc1768.pdf
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* ARM 926 based SoCs
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- at91sam9260
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+ Datasheet
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http://www.atmel.com/Images/doc6221.pdf
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- at91sam9xe
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+ Datasheet
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http://www.atmel.com/Images/Atmel-6254-32-bit-ARM926EJ-S-Embedded-Microprocessor-SAM9XE_Datasheet.pdf
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- at91sam9261
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+ Datasheet
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http://www.atmel.com/Images/doc6062.pdf
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- at91sam9263
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+ Datasheet
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http://www.atmel.com/Images/Atmel_6249_32-bit-ARM926EJ-S-Microcontroller_SAM9263_Datasheet.pdf
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- at91sam9rl
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+ Datasheet
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http://www.atmel.com/Images/doc6289.pdf
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- at91sam9g20
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+ Datasheet
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http://www.atmel.com/Images/doc6384.pdf
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- at91sam9g45 family
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- at91sam9g45
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- at91sam9g46
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- at91sam9m10
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- at91sam9m11 (device superset)
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+ Datasheet
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http://www.atmel.com/Images/Atmel-6437-32-bit-ARM926-Embedded-Microprocessor-SAM9M11_Datasheet.pdf
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- at91sam9x5 family (aka "The 5 series")
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- at91sam9g15
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- at91sam9g25
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- at91sam9g35
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- at91sam9x25
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- at91sam9x35
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+ Datasheet (can be considered as covering the whole family)
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http://www.atmel.com/Images/Atmel_11055_32-bit-ARM926EJ-S-Microcontroller_SAM9X35_Datasheet.pdf
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- at91sam9n12
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+ Datasheet
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http://www.atmel.com/Images/Atmel_11063_32-bit-ARM926EJ-S-Microcontroller_SAM9N12CN11CN12_Datasheet.pdf
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* ARM Cortex-A5 based SoCs
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- sama5d3 family
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- sama5d31
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- sama5d33
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- sama5d34
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- sama5d35
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- sama5d36 (device superset)
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+ Datasheet
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http://www.atmel.com/Images/Atmel-11121-32-bit-Cortex-A5-Microcontroller-SAMA5D3_Datasheet.pdf
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* ARM Cortex-A5 + NEON based SoCs
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- sama5d4 family
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- sama5d41
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- sama5d42
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- sama5d43
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- sama5d44 (device superset)
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+ Datasheet
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http://www.atmel.com/Images/Atmel-11238-32-bit-Cortex-A5-Microcontroller-SAMA5D4_Datasheet.pdf
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Linux kernel information
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------------------------
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Linux kernel mach directory: arch/arm/mach-at91
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MAINTAINERS entry is: "ARM/ATMEL AT91RM9200 AND AT91SAM ARM ARCHITECTURES"
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Device Tree for AT91 SoCs and boards
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------------------------------------
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All AT91 SoCs are converted to Device Tree. Since Linux 3.19, these products
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must use this method to boot the Linux kernel.
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Work In Progress statement:
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Device Tree files and Device Tree bindings that apply to AT91 SoCs and boards are
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considered as "Unstable". To be completely clear, any at91 binding can change at
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any time. So, be sure to use a Device Tree Binary and a Kernel Image generated from
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the same source tree.
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Please refer to the Documentation/devicetree/bindings/ABI.txt file for a
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definition of a "Stable" binding/ABI.
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This statement will be removed by AT91 MAINTAINERS when appropriate.
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Naming conventions and best practice:
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- SoCs Device Tree Source Include files are named after the official name of
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the product (at91sam9g20.dtsi or sama5d33.dtsi for instance).
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- Device Tree Source Include files (.dtsi) are used to collect common nodes that can be
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shared across SoCs or boards (sama5d3.dtsi or at91sam9x5cm.dtsi for instance).
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When collecting nodes for a particular peripheral or topic, the identifier have to
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be placed at the end of the file name, separated with a "_" (at91sam9x5_can.dtsi
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or sama5d3_gmac.dtsi for example).
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- board Device Tree Source files (.dts) are prefixed by the string "at91-" so
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that they can be identified easily. Note that some files are historical exceptions
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to this rule (sama5d3[13456]ek.dts, usb_a9g20.dts or animeo_ip.dts for example).