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Documentation / arm / Samsung-S3C24XX / Overview.txt




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Based on kernel version 3.15.4. Page generated on 2014-07-07 08:59 EST.

1				S3C24XX ARM Linux Overview
2				==========================
3	
4	
5	
6	Introduction
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	
25	Configuration
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	
36	Layout
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	
51	arch/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	
68	Machines
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	
128	Adding 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	
154	I2C
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	
161	RTC
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	
171	Watchdog
172	--------
173	
174	  The onchip watchdog is available via the standard watchdog
175	  interface.
176	
177	
178	NAND
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	
188	SD/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	
199	Serial
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	
212	GPIO
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	
229	Clock 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	
237	Suspend 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	
246	SPI
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	
254	LEDs
255	----
256	
257	  There is support for GPIO based LEDs via a platform driver
258	  in the LED subsystem.
259	
260	
261	Platform 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	
299	Port 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	
315	Document Author
316	---------------
317	
318	Ben Dooks, Copyright 2004-2006 Simtec Electronics
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