1			S3C24XX ARM Linux Overview
2			==========================
3
4
5
6Introduction
7------------
8
9  The Samsung S3C24XX range of ARM9 System-on-Chip CPUs are supported
10  by the 's3c2410' architecture of ARM Linux. Currently the S3C2410,
11  S3C2412, S3C2413, S3C2416, S3C2440, S3C2442, S3C2443 and S3C2450 devices
12  are supported.
13
14  Support for the S3C2400 and S3C24A0 series was never completed and the
15  corresponding code has been removed after a while.  If someone wishes to
16  revive this effort, partial support can be retrieved from earlier Linux
17  versions.
18
19  The S3C2416 and S3C2450 devices are very similar and S3C2450 support is
20  included under the arch/arm/mach-s3c2416 directory. Note, whilst core
21  support for these SoCs is in, work on some of the extra peripherals
22  and extra interrupts is still ongoing.
23
24
25Configuration
26-------------
27
28  A generic S3C2410 configuration is provided, and can be used as the
29  default by `make s3c2410_defconfig`. This configuration has support
30  for all the machines, and the commonly used features on them.
31
32  Certain machines may have their own default configurations as well,
33  please check the machine specific documentation.
34
35
36Layout
37------
38
39  The core support files are located in the platform code contained in
40  arch/arm/plat-s3c24xx with headers in include/asm-arm/plat-s3c24xx.
41  This directory should be kept to items shared between the platform
42  code (arch/arm/plat-s3c24xx) and the arch/arm/mach-s3c24* code.
43
44  Each cpu has a directory with the support files for it, and the
45  machines that carry the device. For example S3C2410 is contained
46  in arch/arm/mach-s3c2410 and S3C2440 in arch/arm/mach-s3c2440
47
48  Register, kernel and platform data definitions are held in the
49  arch/arm/mach-s3c2410 directory./include/mach
50
51arch/arm/plat-s3c24xx:
52
53  Files in here are either common to all the s3c24xx family,
54  or are common to only some of them with names to indicate this
55  status. The files that are not common to all are generally named
56  with the initial cpu they support in the series to ensure a short
57  name without any possibility of confusion with newer devices.
58
59  As an example, initially s3c244x would cover s3c2440 and s3c2442, but
60  with the s3c2443 which does not share many of the same drivers in
61  this directory, the name becomes invalid. We stick to s3c2440-<x>
62  to indicate a driver that is s3c2440 and s3c2442 compatible.
63
64  This does mean that to find the status of any given SoC, a number
65  of directories may need to be searched.
66
67
68Machines
69--------
70
71  The currently supported machines are as follows:
72
73  Simtec Electronics EB2410ITX (BAST)
74
75    A general purpose development board, see EB2410ITX.txt for further
76    details
77
78  Simtec Electronics IM2440D20 (Osiris)
79
80    CPU Module from Simtec Electronics, with a S3C2440A CPU, nand flash
81    and a PCMCIA controller.
82
83  Samsung SMDK2410
84
85    Samsung's own development board, geared for PDA work.
86
87  Samsung/Aiji SMDK2412
88
89    The S3C2412 version of the SMDK2440.
90
91  Samsung/Aiji SMDK2413
92
93    The S3C2412 version of the SMDK2440.
94
95  Samsung/Meritech SMDK2440
96
97    The S3C2440 compatible version of the SMDK2440, which has the
98    option of an S3C2440 or S3C2442 CPU module.
99
100  Thorcom VR1000
101
102    Custom embedded board
103
104  HP IPAQ 1940
105
106    Handheld (IPAQ), available in several varieties
107
108  HP iPAQ rx3715
109
110    S3C2440 based IPAQ, with a number of variations depending on
111    features shipped.
112
113  Acer N30
114
115    A S3C2410 based PDA from Acer.  There is a Wiki page at
116    http://handhelds.org/moin/moin.cgi/AcerN30Documentation .
117
118  AML M5900
119
120    American Microsystems' M5900
121
122  Nex Vision Nexcoder
123  Nex Vision Otom
124
125    Two machines by Nex Vision
126
127
128Adding New Machines
129-------------------
130
131  The architecture has been designed to support as many machines as can
132  be configured for it in one kernel build, and any future additions
133  should keep this in mind before altering items outside of their own
134  machine files.
135
136  Machine definitions should be kept in linux/arch/arm/mach-s3c2410,
137  and there are a number of examples that can be looked at.
138
139  Read the kernel patch submission policies as well as the
140  Documentation/arm directory before submitting patches. The
141  ARM kernel series is managed by Russell King, and has a patch system
142  located at http://www.arm.linux.org.uk/developer/patches/
143  as well as mailing lists that can be found from the same site.
144
145  As a courtesy, please notify <ben-linux@fluff.org> of any new
146  machines or other modifications.
147
148  Any large scale modifications, or new drivers should be discussed
149  on the ARM kernel mailing list (linux-arm-kernel) before being
150  attempted. See http://www.arm.linux.org.uk/mailinglists/ for the
151  mailing list information.
152
153
154I2C
155---
156
157  The hardware I2C core in the CPU is supported in single master
158  mode, and can be configured via platform data.
159
160
161RTC
162---
163
164  Support for the onboard RTC unit, including alarm function.
165
166  This has recently been upgraded to use the new RTC core,
167  and the module has been renamed to rtc-s3c to fit in with
168  the new rtc naming scheme.
169
170
171Watchdog
172--------
173
174  The onchip watchdog is available via the standard watchdog
175  interface.
176
177
178NAND
179----
180
181  The current kernels now have support for the s3c2410 NAND
182  controller. If there are any problems the latest linux-mtd
183  code can be found from http://www.linux-mtd.infradead.org/
184
185  For more information see Documentation/arm/Samsung-S3C24XX/NAND.txt
186
187
188SD/MMC
189------
190
191  The SD/MMC hardware pre S3C2443 is supported in the current
192  kernel, the driver is drivers/mmc/host/s3cmci.c and supports
193  1 and 4 bit SD or MMC cards.
194
195  The SDIO behaviour of this driver has not been fully tested. There is no
196  current support for hardware SDIO interrupts.
197
198
199Serial
200------
201
202  The s3c2410 serial driver provides support for the internal
203  serial ports. These devices appear as /dev/ttySAC0 through 3.
204
205  To create device nodes for these, use the following commands
206
207    mknod ttySAC0 c 204 64
208    mknod ttySAC1 c 204 65
209    mknod ttySAC2 c 204 66
210
211
212GPIO
213----
214
215  The core contains support for manipulating the GPIO, see the
216  documentation in GPIO.txt in the same directory as this file.
217
218  Newer kernels carry GPIOLIB, and support is being moved towards
219  this with some of the older support in line to be removed.
220
221  As of v2.6.34, the move towards using gpiolib support is almost
222  complete, and very little of the old calls are left.
223
224  See Documentation/arm/Samsung-S3C24XX/GPIO.txt for the S3C24XX specific
225  support and Documentation/arm/Samsung/GPIO.txt for the core Samsung
226  implementation.
227
228
229Clock Management
230----------------
231
232  The core provides the interface defined in the header file
233  include/asm-arm/hardware/clock.h, to allow control over the
234  various clock units
235
236
237Suspend to RAM
238--------------
239
240  For boards that provide support for suspend to RAM, the
241  system can be placed into low power suspend.
242
243  See Suspend.txt for more information.
244
245
246SPI
247---
248
249  SPI drivers are available for both the in-built hardware
250  (although there is no DMA support yet) and a generic
251  GPIO based solution.
252
253
254LEDs
255----
256
257  There is support for GPIO based LEDs via a platform driver
258  in the LED subsystem.
259
260
261Platform Data
262-------------
263
264  Whenever a device has platform specific data that is specified
265  on a per-machine basis, care should be taken to ensure the
266  following:
267
268    1) that default data is not left in the device to confuse the
269       driver if a machine does not set it at startup
270
271    2) the data should (if possible) be marked as __initdata,
272       to ensure that the data is thrown away if the machine is
273       not the one currently in use.
274
275       The best way of doing this is to make a function that
276       kmalloc()s an area of memory, and copies the __initdata
277       and then sets the relevant device's platform data. Making
278       the function `__init` takes care of ensuring it is discarded
279       with the rest of the initialisation code
280
281       static __init void s3c24xx_xxx_set_platdata(struct xxx_data *pd)
282       {
283           struct s3c2410_xxx_mach_info *npd;
284
285	   npd = kmalloc(sizeof(struct s3c2410_xxx_mach_info), GFP_KERNEL);
286	   if (npd) {
287	      memcpy(npd, pd, sizeof(struct s3c2410_xxx_mach_info));
288	      s3c_device_xxx.dev.platform_data = npd;
289	   } else {
290              printk(KERN_ERR "no memory for xxx platform data\n");
291	   }
292	}
293
294	Note, since the code is marked as __init, it should not be
295	exported outside arch/arm/mach-s3c2410/, or exported to
296	modules via EXPORT_SYMBOL() and related functions.
297
298
299Port Contributors
300-----------------
301
302  Ben Dooks (BJD)
303  Vincent Sanders
304  Herbert Potzl
305  Arnaud Patard (RTP)
306  Roc Wu
307  Klaus Fetscher
308  Dimitry Andric
309  Shannon Holland
310  Guillaume Gourat (NexVision)
311  Christer Weinigel (wingel) (Acer N30)
312  Lucas Correia Villa Real (S3C2400 port)
313
314
315Document Author
316---------------
317
318Ben Dooks, Copyright 2004-2006 Simtec Electronics
319