overview.rst 8.7 KB

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  1. ==========================
  2. S3C24XX ARM Linux Overview
  3. ==========================
  4. Introduction
  5. ------------
  6. The Samsung S3C24XX range of ARM9 System-on-Chip CPUs are supported
  7. by the 's3c2410' architecture of ARM Linux. Currently the S3C2410,
  8. S3C2412, S3C2413, S3C2416, S3C2440, S3C2442, S3C2443 and S3C2450 devices
  9. are supported.
  10. Support for the S3C2400 and S3C24A0 series was never completed and the
  11. corresponding code has been removed after a while. If someone wishes to
  12. revive this effort, partial support can be retrieved from earlier Linux
  13. versions.
  14. The S3C2416 and S3C2450 devices are very similar and S3C2450 support is
  15. included under the arch/arm/mach-s3c2416 directory. Note, while core
  16. support for these SoCs is in, work on some of the extra peripherals
  17. and extra interrupts is still ongoing.
  18. Configuration
  19. -------------
  20. A generic S3C2410 configuration is provided, and can be used as the
  21. default by `make s3c2410_defconfig`. This configuration has support
  22. for all the machines, and the commonly used features on them.
  23. Certain machines may have their own default configurations as well,
  24. please check the machine specific documentation.
  25. Layout
  26. ------
  27. The core support files are located in the platform code contained in
  28. arch/arm/plat-s3c24xx with headers in include/asm-arm/plat-s3c24xx.
  29. This directory should be kept to items shared between the platform
  30. code (arch/arm/plat-s3c24xx) and the arch/arm/mach-s3c24* code.
  31. Each cpu has a directory with the support files for it, and the
  32. machines that carry the device. For example S3C2410 is contained
  33. in arch/arm/mach-s3c2410 and S3C2440 in arch/arm/mach-s3c2440
  34. Register, kernel and platform data definitions are held in the
  35. arch/arm/mach-s3c2410 directory./include/mach
  36. arch/arm/plat-s3c24xx:
  37. Files in here are either common to all the s3c24xx family,
  38. or are common to only some of them with names to indicate this
  39. status. The files that are not common to all are generally named
  40. with the initial cpu they support in the series to ensure a short
  41. name without any possibility of confusion with newer devices.
  42. As an example, initially s3c244x would cover s3c2440 and s3c2442, but
  43. with the s3c2443 which does not share many of the same drivers in
  44. this directory, the name becomes invalid. We stick to s3c2440-<x>
  45. to indicate a driver that is s3c2440 and s3c2442 compatible.
  46. This does mean that to find the status of any given SoC, a number
  47. of directories may need to be searched.
  48. Machines
  49. --------
  50. The currently supported machines are as follows:
  51. Simtec Electronics EB2410ITX (BAST)
  52. A general purpose development board, see EB2410ITX.txt for further
  53. details
  54. Simtec Electronics IM2440D20 (Osiris)
  55. CPU Module from Simtec Electronics, with a S3C2440A CPU, nand flash
  56. and a PCMCIA controller.
  57. Samsung SMDK2410
  58. Samsung's own development board, geared for PDA work.
  59. Samsung/Aiji SMDK2412
  60. The S3C2412 version of the SMDK2440.
  61. Samsung/Aiji SMDK2413
  62. The S3C2412 version of the SMDK2440.
  63. Samsung/Meritech SMDK2440
  64. The S3C2440 compatible version of the SMDK2440, which has the
  65. option of an S3C2440 or S3C2442 CPU module.
  66. Thorcom VR1000
  67. Custom embedded board
  68. HP IPAQ 1940
  69. Handheld (IPAQ), available in several varieties
  70. HP iPAQ rx3715
  71. S3C2440 based IPAQ, with a number of variations depending on
  72. features shipped.
  73. Acer N30
  74. A S3C2410 based PDA from Acer. There is a Wiki page at
  75. http://handhelds.org/moin/moin.cgi/AcerN30Documentation .
  76. AML M5900
  77. American Microsystems' M5900
  78. Nex Vision Nexcoder
  79. Nex Vision Otom
  80. Two machines by Nex Vision
  81. Adding New Machines
  82. -------------------
  83. The architecture has been designed to support as many machines as can
  84. be configured for it in one kernel build, and any future additions
  85. should keep this in mind before altering items outside of their own
  86. machine files.
  87. Machine definitions should be kept in linux/arch/arm/mach-s3c2410,
  88. and there are a number of examples that can be looked at.
  89. Read the kernel patch submission policies as well as the
  90. Documentation/arm directory before submitting patches. The
  91. ARM kernel series is managed by Russell King, and has a patch system
  92. located at http://www.arm.linux.org.uk/developer/patches/
  93. as well as mailing lists that can be found from the same site.
  94. As a courtesy, please notify <ben-linux@fluff.org> of any new
  95. machines or other modifications.
  96. Any large scale modifications, or new drivers should be discussed
  97. on the ARM kernel mailing list (linux-arm-kernel) before being
  98. attempted. See http://www.arm.linux.org.uk/mailinglists/ for the
  99. mailing list information.
  100. I2C
  101. ---
  102. The hardware I2C core in the CPU is supported in single master
  103. mode, and can be configured via platform data.
  104. RTC
  105. ---
  106. Support for the onboard RTC unit, including alarm function.
  107. This has recently been upgraded to use the new RTC core,
  108. and the module has been renamed to rtc-s3c to fit in with
  109. the new rtc naming scheme.
  110. Watchdog
  111. --------
  112. The onchip watchdog is available via the standard watchdog
  113. interface.
  114. NAND
  115. ----
  116. The current kernels now have support for the s3c2410 NAND
  117. controller. If there are any problems the latest linux-mtd
  118. code can be found from http://www.linux-mtd.infradead.org/
  119. For more information see Documentation/arm/samsung-s3c24xx/nand.rst
  120. SD/MMC
  121. ------
  122. The SD/MMC hardware pre S3C2443 is supported in the current
  123. kernel, the driver is drivers/mmc/host/s3cmci.c and supports
  124. 1 and 4 bit SD or MMC cards.
  125. The SDIO behaviour of this driver has not been fully tested. There is no
  126. current support for hardware SDIO interrupts.
  127. Serial
  128. ------
  129. The s3c2410 serial driver provides support for the internal
  130. serial ports. These devices appear as /dev/ttySAC0 through 3.
  131. To create device nodes for these, use the following commands
  132. mknod ttySAC0 c 204 64
  133. mknod ttySAC1 c 204 65
  134. mknod ttySAC2 c 204 66
  135. GPIO
  136. ----
  137. The core contains support for manipulating the GPIO, see the
  138. documentation in GPIO.txt in the same directory as this file.
  139. Newer kernels carry GPIOLIB, and support is being moved towards
  140. this with some of the older support in line to be removed.
  141. As of v2.6.34, the move towards using gpiolib support is almost
  142. complete, and very little of the old calls are left.
  143. See Documentation/arm/samsung-s3c24xx/gpio.rst for the S3C24XX specific
  144. support and Documentation/arm/samsung/gpio.rst for the core Samsung
  145. implementation.
  146. Clock Management
  147. ----------------
  148. The core provides the interface defined in the header file
  149. include/asm-arm/hardware/clock.h, to allow control over the
  150. various clock units
  151. Suspend to RAM
  152. --------------
  153. For boards that provide support for suspend to RAM, the
  154. system can be placed into low power suspend.
  155. See Suspend.txt for more information.
  156. SPI
  157. ---
  158. SPI drivers are available for both the in-built hardware
  159. (although there is no DMA support yet) and a generic
  160. GPIO based solution.
  161. LEDs
  162. ----
  163. There is support for GPIO based LEDs via a platform driver
  164. in the LED subsystem.
  165. Platform Data
  166. -------------
  167. Whenever a device has platform specific data that is specified
  168. on a per-machine basis, care should be taken to ensure the
  169. following:
  170. 1) that default data is not left in the device to confuse the
  171. driver if a machine does not set it at startup
  172. 2) the data should (if possible) be marked as __initdata,
  173. to ensure that the data is thrown away if the machine is
  174. not the one currently in use.
  175. The best way of doing this is to make a function that
  176. kmalloc()s an area of memory, and copies the __initdata
  177. and then sets the relevant device's platform data. Making
  178. the function `__init` takes care of ensuring it is discarded
  179. with the rest of the initialisation code::
  180. static __init void s3c24xx_xxx_set_platdata(struct xxx_data *pd)
  181. {
  182. struct s3c2410_xxx_mach_info *npd;
  183. npd = kmalloc(sizeof(struct s3c2410_xxx_mach_info), GFP_KERNEL);
  184. if (npd) {
  185. memcpy(npd, pd, sizeof(struct s3c2410_xxx_mach_info));
  186. s3c_device_xxx.dev.platform_data = npd;
  187. } else {
  188. printk(KERN_ERR "no memory for xxx platform data\n");
  189. }
  190. }
  191. Note, since the code is marked as __init, it should not be
  192. exported outside arch/arm/mach-s3c2410/, or exported to
  193. modules via EXPORT_SYMBOL() and related functions.
  194. Port Contributors
  195. -----------------
  196. Ben Dooks (BJD)
  197. Vincent Sanders
  198. Herbert Potzl
  199. Arnaud Patard (RTP)
  200. Roc Wu
  201. Klaus Fetscher
  202. Dimitry Andric
  203. Shannon Holland
  204. Guillaume Gourat (NexVision)
  205. Christer Weinigel (wingel) (Acer N30)
  206. Lucas Correia Villa Real (S3C2400 port)
  207. Document Author
  208. ---------------
  209. Ben Dooks, Copyright 2004-2006 Simtec Electronics