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