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,  S3C2412, S3C2413, S3C2440, S3C2442 and S3C2443 devices are supported.  Support for the S3C2400 and S3C24A0 series are 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.Layout------  The core support files are located in the platform code contained in  arch/arm/plat-s3c24xx with headers in include/asm-arm/plat-s3c24xx.  This directory should be kept to items shared between the platform  code (arch/arm/plat-s3c24xx) and the arch/arm/mach-s3c24* code.  Each cpu has a directory with the support files for it, and the  machines that carry the device. For example S3C2410 is contained  in arch/arm/mach-s3c2410 and S3C2440 in arch/arm/mach-s3c2440  Register, kernel and platform data definitions are held in the  arch/arm/mach-s3c2410 directory./include/macharch/arm/plat-s3c24xx:  Files in here are either common to all the s3c24xx family,  or are common to only some of them with names to indicate this  status. The files that are not common to all are generally named  with the initial cpu they support in the series to ensure a short  name without any possibility of confusion with newer devices.  As an example, initially s3c244x would cover s3c2440 and s3c2442, but  with the s3c2443 which does not share many of the same drivers in  this directory, the name becomes invalid. We stick to s3c2440-<x>  to indicate a driver that is s3c2440 and s3c2442 compatible.  This does mean that to find the status of any given SoC, a number  of directories may need to be searched.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/Aiji SMDK2412    The S3C2412 version of the SMDK2440.  Samsung/Aiji SMDK2413    The S3C2412 version of the SMDK2440.  Samsung/Meritech SMDK2440    The S3C2440 compatible version of the SMDK2440, which has the    option of an S3C2440 or S3C2442 CPU module.  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 .  AML M5900    American Microsystems' M5900  Nex Vision Nexcoder  Nex Vision Otom    Two machines by Nex VisionAdding New Machines-------------------  The architecture 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.  This has recently been upgraded to use the new RTC core,  and the module has been renamed to rtc-s3c to fit in with  the new rtc naming scheme.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  code can be found from http://www.linux-mtd.infradead.org/  For more information see Documentation/arm/Samsung-S3C24XX/NAND.txtSD/MMC------  The SD/MMC hardware pre S3C2443 is supported in the current  kernel, the driver is drivers/mmc/host/s3cmci.c and supports  1 and 4 bit SD or MMC cards.  The SDIO behaviour of this driver has not been fully tested. There is no  current support for hardware SDIO interrupts.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 66GPIO----  The core contains support for manipulating the GPIO, see the  documentation in GPIO.txt in the same directory as this file.  Newer kernels carry GPIOLIB, and support is being moved towards  this with some of the older support in line to be removed.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 unitsSuspend 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.SPI---  SPI drivers are available for both the in-built hardware  (although there is no DMA support yet) and a generic  GPIO based solution.LEDs----  There is support for GPIO based LEDs via a platform driver  in the LED subsystem.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 Author---------------Ben Dooks, (c) 2004-2005,2006 Simtec Electronics