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+==========================
+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, S3C2416, S3C2440, S3C2442, S3C2443 and S3C2450 devices
+ are supported.
+
+ Support for the S3C2400 and S3C24A0 series was never completed and the
+ corresponding code has been removed after a while. If someone wishes to
+ revive this effort, partial support can be retrieved from earlier Linux
+ versions.
+
+ The S3C2416 and S3C2450 devices are very similar and S3C2450 support is
+ included under the arch/arm/mach-s3c directory. Note, while core
+ support for these SoCs is in, work on some of the extra peripherals
+ and extra interrupts is still ongoing.
+
+
+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, register, kernel and paltform data are located in the
+ platform code contained in arch/arm/mach-s3c with headers in
+ arch/arm/mach-s3c/include
+
+arch/arm/mach-s3c:
+
+ 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 Vision
+
+
+Adding 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 arch/arm/mach-s3c,
+ 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.rst
+
+
+SD/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 66
+
+
+GPIO
+----
+
+ 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.
+
+ As of v2.6.34, the move towards using gpiolib support is almost
+ complete, and very little of the old calls are left.
+
+ See Documentation/arm/samsung-s3c24xx/gpio.rst for the S3C24XX specific
+ support and Documentation/arm/samsung/gpio.rst for the core Samsung
+ implementation.
+
+
+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.
+
+
+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-s3c/, 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, Copyright 2004-2006 Simtec Electronics