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122 lines
3.3 KiB
122 lines
3.3 KiB
S3C2410 GPIO Control
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====================
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Introduction
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------------
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The s3c2410 kernel provides an interface to configure and
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manipulate the state of the GPIO pins, and find out other
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information about them.
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There are a number of conditions attached to the configuration
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of the s3c2410 GPIO system, please read the Samsung provided
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data-sheet/users manual to find out the complete list.
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Headers
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-------
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See include/asm-arm/arch-s3c2410/regs-gpio.h for the list
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of GPIO pins, and the configuration values for them. This
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is included by using #include <asm/arch/regs-gpio.h>
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The GPIO management functions are defined in the hardware
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header include/asm-arm/arch-s3c2410/hardware.h which can be
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included by #include <asm/arch/hardware.h>
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A useful ammount of documentation can be found in the hardware
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header on how the GPIO functions (and others) work.
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Whilst a number of these functions do make some checks on what
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is passed to them, for speed of use, they may not always ensure
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that the user supplied data to them is correct.
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PIN Numbers
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-----------
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Each pin has an unique number associated with it in regs-gpio.h,
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eg S3C2410_GPA0 or S3C2410_GPF1. These defines are used to tell
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the GPIO functions which pin is to be used.
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Configuring a pin
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-----------------
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The following function allows the configuration of a given pin to
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be changed.
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void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function);
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Eg:
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s3c2410_gpio_cfgpin(S3C2410_GPA0, S3C2410_GPA0_ADDR0);
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s3c2410_gpio_cfgpin(S3C2410_GPE8, S3C2410_GPE8_SDDAT1);
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which would turn GPA0 into the lowest Address line A0, and set
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GPE8 to be connected to the SDIO/MMC controller's SDDAT1 line.
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Reading the current configuration
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---------------------------------
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The current configuration of a pin can be read by using:
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s3c2410_gpio_getcfg(unsigned int pin);
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The return value will be from the same set of values which can be
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passed to s3c2410_gpio_cfgpin().
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Configuring a pull-up resistor
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------------------------------
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A large proportion of the GPIO pins on the S3C2410 can have weak
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pull-up resistors enabled. This can be configured by the following
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function:
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void s3c2410_gpio_pullup(unsigned int pin, unsigned int to);
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Where the to value is zero to set the pull-up off, and 1 to enable
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the specified pull-up. Any other values are currently undefined.
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Getting the state of a PIN
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--------------------------
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The state of a pin can be read by using the function:
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unsigned int s3c2410_gpio_getpin(unsigned int pin);
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This will return either zero or non-zero. Do not count on this
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function returning 1 if the pin is set.
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Setting the state of a PIN
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--------------------------
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The value an pin is outputing can be modified by using the following:
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void s3c2410_gpio_setpin(unsigned int pin, unsigned int to);
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Which sets the given pin to the value. Use 0 to write 0, and 1 to
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set the output to 1.
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Getting the IRQ number associated with a PIN
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--------------------------------------------
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The following function can map the given pin number to an IRQ
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number to pass to the IRQ system.
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int s3c2410_gpio_getirq(unsigned int pin);
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Note, not all pins have an IRQ.
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Authour
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-------
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Ben Dooks, 03 October 2004
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(c) 2004 Ben Dooks, Simtec Electronics
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