android_kernel_xiaomi_sm8350/Documentation/arm/Samsung-S3C24XX/Overview.txt

			S3C24XX ARM Linux Overview
			==========================



Introduction
------------

  The Samsung S3C24XX range of ARM9 System-on-Chip CPUs are supported
  by the 's3c2410' architecture of ARM Linux. Currently the S3C2410 and
  the S3C2440 are supported CPUs.

  Support for the S3C2400 series is in progress.


Configuration
-------------

  A generic S3C2410 configuration is provided, and can be used as the
  default by `make s3c2410_defconfig`. This configuration has support
  for all the machines, and the commonly used features on them.

  Certain machines may have their own default configurations as well,
  please check the machine specific documentation.


Machines
--------

  The currently supported machines are as follows:

  Simtec Electronics EB2410ITX (BAST)

    A general purpose development board, see EB2410ITX.txt for further
    details

  Simtec Electronics IM2440D20 (Osiris)

    CPU Module from Simtec Electronics, with a S3C2440A CPU, nand flash
    and a PCMCIA controller.

  Samsung SMDK2410

    Samsung's own development board, geared for PDA work.

  Samsung/Meritech SMDK2440

    The S3C2440 compatible version of the SMDK2440

  Thorcom VR1000

    Custom embedded board

  HP IPAQ 1940

    Handheld (IPAQ), available in several varieties

  HP iPAQ rx3715

    S3C2440 based IPAQ, with a number of variations depending on
    features shipped.

  Acer N30

    A S3C2410 based PDA from Acer.  There is a Wiki page at
    http://handhelds.org/moin/moin.cgi/AcerN30Documentation .


Adding New Machines
-------------------

  The archicture has been designed to support as many machines as can
  be configured for it in one kernel build, and any future additions
  should keep this in mind before altering items outside of their own
  machine files.

  Machine definitions should be kept in linux/arch/arm/mach-s3c2410,
  and there are a number of examples that can be looked at.

  Read the kernel patch submission policies as well as the
  Documentation/arm directory before submitting patches. The
  ARM kernel series is managed by Russell King, and has a patch system
  located at http://www.arm.linux.org.uk/developer/patches/
  as well as mailing lists that can be found from the same site.

  As a courtesy, please notify <ben-linux@fluff.org> of any new
  machines or other modifications.

  Any large scale modifications, or new drivers should be discussed
  on the ARM kernel mailing list (linux-arm-kernel) before being
  attempted. See http://www.arm.linux.org.uk/mailinglists/ for the
  mailing list information.


I2C
---

  The hardware I2C core in the CPU is supported in single master
  mode, and can be configured via platform data.


RTC
---

  Support for the onboard RTC unit, including alarm function.


Watchdog
--------

  The onchip watchdog is available via the standard watchdog
  interface.


NAND
----

  The current kernels now have support for the s3c2410 NAND
  controller. If there are any problems the latest linux-mtd
  CVS can be found from http://www.linux-mtd.infradead.org/


Serial
------

  The s3c2410 serial driver provides support for the internal
  serial ports. These devices appear as /dev/ttySAC0 through 3.

  To create device nodes for these, use the following commands

    mknod ttySAC0 c 204 64
    mknod ttySAC1 c 204 65
    mknod ttySAC2 c 204 66


GPIO
----

  The core contains support for manipulating the GPIO, see the
  documentation in GPIO.txt in the same directory as this file.


Clock Management
----------------

  The core provides the interface defined in the header file
  include/asm-arm/hardware/clock.h, to allow control over the
  various clock units


Suspend to RAM
--------------

  For boards that provide support for suspend to RAM, the
  system can be placed into low power suspend.

  See Suspend.txt for more information.


Platform Data
-------------

  Whenever a device has platform specific data that is specified
  on a per-machine basis, care should be taken to ensure the
  following:

    1) that default data is not left in the device to confuse the
       driver if a machine does not set it at startup

    2) the data should (if possible) be marked as __initdata,
       to ensure that the data is thrown away if the machine is
       not the one currently in use.

       The best way of doing this is to make a function that
       kmalloc()s an area of memory, and copies the __initdata
       and then sets the relevant device's platform data. Making
       the function `__init` takes care of ensuring it is discarded
       with the rest of the initialisation code

       static __init void s3c24xx_xxx_set_platdata(struct xxx_data *pd)
       {
           struct s3c2410_xxx_mach_info *npd;

	   npd = kmalloc(sizeof(struct s3c2410_xxx_mach_info), GFP_KERNEL);
	   if (npd) {
	      memcpy(npd, pd, sizeof(struct s3c2410_xxx_mach_info));
	      s3c_device_xxx.dev.platform_data = npd;
	   } else {
              printk(KERN_ERR "no memory for xxx platform data\n");
	   }
	}

	Note, since the code is marked as __init, it should not be
	exported outside arch/arm/mach-s3c2410/, or exported to
	modules via EXPORT_SYMBOL() and related functions.


Port Contributors
-----------------

  Ben Dooks (BJD)
  Vincent Sanders
  Herbert Potzl
  Arnaud Patard (RTP)
  Roc Wu
  Klaus Fetscher
  Dimitry Andric
  Shannon Holland
  Guillaume Gourat (NexVision)
  Christer Weinigel (wingel) (Acer N30)
  Lucas Correia Villa Real (S3C2400 port)


Document Changes
----------------

  05 Sep 2004 - BJD - Added Document Changes section
  05 Sep 2004 - BJD - Added Klaus Fetscher to list of contributors
  25 Oct 2004 - BJD - Added Dimitry Andric to list of contributors
  25 Oct 2004 - BJD - Updated the MTD from the 2.6.9 merge
  21 Jan 2005 - BJD - Added rx3715, added Shannon to contributors
  10 Feb 2005 - BJD - Added Guillaume Gourat to contributors
  02 Mar 2005 - BJD - Added SMDK2440 to list of machines
  06 Mar 2005 - BJD - Added Christer Weinigel
  08 Mar 2005 - BJD - Added LCVR to list of people, updated introduction
  08 Mar 2005 - BJD - Added section on adding machines
  09 Sep 2005 - BJD - Added section on platform data
  11 Feb 2006 - BJD - Added I2C, RTC and Watchdog sections
  11 Feb 2006 - BJD - Added Osiris machine, and S3C2400 information


Document Author
---------------

Ben Dooks, (c) 2004-2005,2006 Simtec Electronics