Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 318 insertions, 0 deletions

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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-s3c2416 directory. Note, whilst 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 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/mach
+
+arch/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 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 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.txt
+
+
+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.txt for the S3C24XX specific
+  support and Documentation/arm/Samsung/GPIO.txt 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-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, Copyright 2004-2006 Simtec Electronics