[PATCH] ARM: at91/Documentation: add a README for Atmel SoCs

[Nicolas Ferre]

Le 09/01/2015 14:20, Nicolas Ferre a écrit :
> 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 at atmel.com>
> Cc: ARM Maintainers <arm at kernel.org>
> ---
>  Documentation/arm/Atmel/README | 120 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 120 insertions(+)
>  create mode 100644 Documentation/arm/Atmel/README
> 
> diff --git a/Documentation/arm/Atmel/README b/Documentation/arm/Atmel/README
> new file mode 100644
> index 000000000000..538f8a556277
> --- /dev/null
> +++ b/Documentation/arm/Atmel/README
> @@ -0,0 +1,120 @@
> +ARM Atmel SoCs (aka AT91)
> +=========================
> +
> +
> +Introduction
> +------------
> +This document gives useful information about the ARM Atmel SoCs that are
> +currently supported in Linux Mainline (you know, the one on kernel.org).
> +
> +It is important to note that the Atmel | SMART ARM-based MPU product line is
> +historically named "AT91" or "at91" throughout the Linux kernel development
> +process even if this product prefix has completely disappeared from the
> +official Atmel product name. Anyway, files, directories, git trees,
> +git branches/tags and email subject always contain this "at91" sub-string.
> +
> +
> +AT91 SoCs
> +---------
> +Documentation and detailled datasheet for each product are available on
> +the Atmel website: http://www.atmel.com.
> +
> +  Flavors:
> +    * ARM 920 based SoC
> +      - at91rm9200
> +        + Datasheet
> +          http://www.atmel.com/Images/doc1768.pdf
> +
> +    * ARM 926 based SoCs
> +      - at91sam9260
> +        + Datasheet
> +          http://www.atmel.com/Images/doc6221.pdf
> +
> +      - at91sam9261
> +        + Datasheet
> +          http://www.atmel.com/Images/doc6062.pdf
> +
> +      - at91sam9263
> +        + Datasheet
> +          http://www.atmel.com/Images/Atmel_6249_32-bit-ARM926EJ-S-Microcontroller_SAM9263_Datasheet.pdf
> +
> +      - at91sam9rl
> +        + Datasheet
> +          http://www.atmel.com/Images/doc6289.pdf
> +
> +      - at91sam9g20
> +        + Datasheet
> +          http://www.atmel.com/Images/doc6384.pdf
> +
> +      - at91sam9g45 family
> +        - at91sam9g45
> +        - at91sam9g46
> +        - at91sam9m10
> +        - at91sam9m11 (device superset)
> +        + Datasheet
> +          http://www.atmel.com/Images/Atmel-6437-32-bit-ARM926-Embedded-Microprocessor-SAM9M11_Datasheet.pdf
> +
> +      - at91sam9x5 family (aka "The 5 series")
> +        - at91sam9g15
> +        - at91sam9g25
> +        - at91sam9g35
> +        - at91sam9x25
> +        - at91sam9x35
> +        + Datasheet (can be considered as covering the whole family)
> +          http://www.atmel.com/Images/Atmel_11055_32-bit-ARM926EJ-S-Microcontroller_SAM9X35_Datasheet.pdf
> +
> +      - at91sam9n12
> +        + Datasheet
> +          http://www.atmel.com/Images/Atmel_11063_32-bit-ARM926EJ-S-Microcontroller_SAM9N12CN11CN12_Datasheet.pdf
> +
> +    * ARM Cortex-A5 based SoCs
> +      - sama5d3 family
> +        - sama5d31
> +        - sama5d33
> +        - sama5d34
> +        - sama5d35
> +        - sama5d36 (device superset)
> +        + Datasheet
> +          http://www.atmel.com/Images/Atmel-11121-32-bit-Cortex-A5-Microcontroller-SAMA5D3_Datasheet.pdf
> +
> +    * ARM Cortex-A5 + NEON based SoCs
> +      - sama5d4 family
> +        - sama5d41
> +        - sama5d42
> +        - sama5d43
> +        - sama5d44 (device superset)
> +        + Datasheet
> +          http://www.atmel.com/Images/Atmel-11238-32-bit-Cortex-A5-Microcontroller-SAMA5D4_Datasheet.pdf
> +
> +
> +Linux kernel information
> +------------------------
> +Linux kernel mach directory: arch/arm/mach-at91
> +MAINTAINERS entry is: "ARM/ATMEL AT91RM9200 AND AT91SAM ARM ARCHITECTURES"
> +
> +
> +Device Tree for AT91 SoCs and boards
> +------------------------------------
> +All AT91 SoCs are converted to Device Tree. Since Linux 3.19, these products
> +must use this method to boot the Linux kernel.
> +
> +Work In Progress statement:
> +Device Tree files and Device Tree bindings that apply to AT91 SoCs and boards are
> +considered as "Unstable". To be completely clear, any at91 binding can change at
> +any time. So, be sure to use a Device Tree Binary and a Kernel Image generated from
> +the same source tree.
> +Please refer to the Documentation/devicetree/bindings/ABI.txt file for a
> +definition of a "Stable" binding/ABI.
> +This statement will be removed by AT91 MAINTAINERS when appropriated.
> +
> +Naming conventions and best practice:
> +- SoCs Device Tree Source Include files are named after the official name of
> +  the product (at91sam9g20.dtsi or sama5d33.dtsi for instance).
> +- Device Tree Source Include files (.dtsi) are used to collect common nodes that can be
> +  shared across SoCs or boards (sama5d3.dtsi or at91sam9x5cm.dtsi for instance).
> +  When collecting nodes for a particular peripheral or topic, the identifier have to
> +  be placed at the end of the file name, separated with a "_" (at91sam9x5_can.dtsi
> +  or sama5d3_gmac.dtsi for example).
> +- board Device Tree Source files (.dts) are prefixed by the string "at91-" so
> +  that they can be identified easily. Note that the sama5d3[13456]ek.dts files
> +  are an historical exception to this rule.

In fact, this set of boards are not the only exception. I will rephrase
the sentence as:
"Note that some files are historical exceptions to this rule
(sama5d3[13456]ek.dts, usb_a9g20.dts or animeo_ip.dts for example)."

Bye,
-- 
Nicolas Ferre