Commit 0642c885 authored by Ben Dooks's avatar Ben Dooks Committed by Russell King

[ARM PATCH] 2122/1: S3C2410 - Documentation updates

Patch from Ben Dooks

Added documentation for the GPIO calls, updated
the overview with more information on the supported
core devices, and updated the state of the EB2410ITX

Signed-off-by: Ben Dooks 
parent 47224407
......@@ -26,4 +26,19 @@ Support
and http://www.simtec.co.uk/products/EB2410ITX/resources.html
MTD
---
The NAND and NOR onboard are currently supported in the linux-mtd cvs,
and are awaiting merge in the mainline. see the linux-mtd project at
http://www.linux-mtd.infradead.org/ for more information.
IDE
---
Both onboard IDE ports are supported, however there is no support for
changing speed of devices, PIO Mode 4 capable drives should be used.
(c) 2004 Ben Dooks, Simtec Electronics
S3C2410 GPIO Control
====================
Introduction
------------
The s3c2410 kernel provides an interface to configure and
manipulate the state of the GPIO pins, and find out other
information about them.
There are a number of conditions attached to the configuration
of the s3c2410 GPIO system, please read the Samsung provided
data-sheet/users manual to find out the complete list.
Headers
-------
See include/asm-arm/arch-s3c2410/regs-gpio.h for the list
of GPIO pins, and the configuration values for them. This
is included by using #include <asm/arch/regs-gpio.h>
The GPIO management functions are defined in the hardware
header include/asm-arm/arch-s3c2410/hardware.h which can be
included by #include <asm/arch/hardware.h>
A useful ammount of documentation can be found in the hardware
header on how the GPIO functions (and others) work.
Whilst a number of these functions do make some checks on what
is passed to them, for speed of use, they may not always ensure
that the user supplied data to them is correct.
PIN Numbers
-----------
Each pin has an unique number associated with it in regs-gpio.h,
eg S3C2410_GPA0 or S3C2410_GPF1. These defines are used to tell
the GPIO functions which pin is to be used.
Configuring a pin
-----------------
The following function allows the configuration of a given pin to
be changed.
void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function);
Eg:
s3c2410_gpio_cfgpin(S3C2410_GPA0, S3C2410_GPA0_ADDR0);
s3c2410_gpio_cfgpin(S3C2410_GPE8, S3C2410_GPE8_SDDAT1);
which would turn GPA0 into the lowest Address line A0, and set
GPE8 to be connected to the SDIO/MMC controller's SDDAT1 line.
Reading the current configuration
---------------------------------
The current configuration of a pin can be read by using:
s3c2410_gpio_getcfg(unsigned int pin);
The return value will be from the same set of values which can be
passed to s3c2410_gpio_cfgpin().
Configuring a pull-up resistor
------------------------------
A large proportion of the GPIO pins on the S3C2410 can have weak
pull-up resistors enabled. This can be configured by the following
function:
void s3c2410_gpio_pullup(unsigned int pin, unsigned int to);
Where the to value is zero to set the pull-up off, and 1 to enable
the specified pull-up. Any other values are currently undefined.
Getting the state of a PIN
--------------------------
The state of a pin can be read by using the function:
unsigned int s3c2410_gpio_getpin(unsigned int pin);
This will return either zero or non-zero. Do not count on this
function returning 1 if the pin is set.
Setting the state of a PIN
--------------------------
The value an pin is outputing can be modified by using the following:
void s3c2410_gpio_setpin(unsigned int pin, unsigned int to);
Which sets the given pin to the value. Use 0 to write 0, and 1 to
set the output to 1.
Getting the IRQ number associated with a PIN
--------------------------------------------
The following function can map the given pin number to an IRQ
number to pass to the IRQ system.
int s3c2410_gpio_getirq(unsigned int pin);
Note, not all pins have an IRQ.
Authour
-------
Ben Dooks, 03 October 2004
(c) 2004 Ben Dooks, Simtec Electronics
......@@ -18,6 +18,9 @@ Configuration
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.
Machines
--------
......@@ -42,10 +45,53 @@ Machines
Handheld (IPAQ), available in several varieties
Contributors
------------
NAND
----
The current kernels do not have direct support for the NAND
controller, the latest linux-mtd CVS has support for this.
See http://www.linux-mtd.infradead.org/
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.
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
Port Contributors
-----------------
Ben Dooks
Vincent Sanders
Herbert Potzl
Arnaud Patard
Roc Wu
Document Author
---------------
Ben Dooks, (c) 2004 Simtec Electronics
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