iMX257 pin configuration function/memory read and write function-EEWORLD

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Three header files to include:

#include "mx257_gpio.h"

#include "mx25_pins.h"

#include "iomux.h"

1. GPIO pin usage

Select Pin Mode->Pin Configuration->Apply for GPIO->Set Pin Input/Output->Read GPIO->Release Pin Mode->

Release GPIO

1. Select the pin mode (ALT0-ALT7)

int mxc_request_iomux(iomux_pin_name_t pin, iomux_pin_cfg_t cfg)

void mxc_free_iomux(iomux_pin_name_t pin, iomux_pin_cfg_t cfg)

Example: mxc_request_iomux(GPIO2_21, MUX_CONFIG_ALT5);

mxc_free_iomux(GPIO2_21, MUX_CONFIG_ALT5);

#define GPIO2_21 MX25_PIN_CLKO (defined in mx25_pin.h)

2. Set the pin configuration

void mxc_iomux_set_pad(iomux_pin_name_t pin, u32 config)

Example: mxc_iomux_set_pad(GPIO2_21, 0);

#define GPIO2_21 MX25_PIN_CLKO (defined in mx25_pin.h)

void mxc_iomux_set_gpr(iomux_gp_func_t gp, bool en);

This function enables/disables the general purpose function for a particular signal.

3. Apply for GPIO

int gpio_request(unsigned gpio, const char *label)

void gpio_free(unsigned gpio)

Example: gpio_request(IOMUX_TO_GPIO(GPIO2_21), "GPIO2_21");

gpio_free(IOMUX_TO_GPIO(GPIO2_21));

4. Set the input and output mode of the pin:

Related documents:

arch/arm/plat-mxc/include/mach/gpio.h

drivers/gpio/gpiolib.c

arch/arm/plat-mxc/gpio.c

In the gpio.h file

① #define gpio_get_value __gpio_get_value is defined (defined in gpiolib.c)

②Call chip->get in __gpio_get_value, and the actual call is to the mxc_gpio_get function in the arch/arm/plat-mxc/gpio.c file

2. Register Operation

1. Memory mapping, IO ports

#define iounmap(addr) ((void)0)

#define ioremap(physaddr, size) (physaddr)

#define ioremap_nocache(physaddr, size) (physaddr)

#define ioremap_writethrough(physaddr, size) (physaddr)

#define ioremap_fullcache(physaddr, size) (physaddr)

2. Read mapped memory, IO port, read byte port (8bit)/word port (16bit)/long word port (32bit)

#define readb(addr) ({ unsigned char __v = (*(volatile unsigned char *) (addr)); __v; })

#define readw(addr) ({ unsigned short __v = (*(volatile unsigned short *) (addr)); __v; })

#define readl(addr) ({ unsigned long __v = (*(volatile unsigned long *) (addr)); __v; })

#define inb(addr) readb (addr)

#define inw(addr) readw (addr)

#define inl(addr) readl (addr)

#define in_8(addr) readb (addr)

#define in_be16(addr) readw (addr)

#define in_be32(addr) readl (addr)

#define inb_p(port) inb((port))

#define inw_p(port) inw((port))

#define inl_p(port) inl((port))

Or: val = *((unsigned char*) (0xc00b0fe4));

io_mem = ioremap(0xfb000000,0x200000);

val = *((unsigned char*)(io_mem+0x100000));

3. Write mapped memory and IO ports

#define writeb(b, addr) (void)((*(volatile unsigned char *) (addr)) = (b))

#define writew(b, addr) (void)((*(volatile unsigned short *) (addr)) = (b))

#define writel(b, addr) (void)((*(volatile unsigned int *) (addr)) = (b))

#define outb(x, addr) ((void) writeb (x, addr))

#define outw(x, addr) ((void) writew (x, addr))

#define outl(x, addr) ((void) writel (x, addr))

#define out_8(addr,x ) outb (x,addr)

#define out_be16(addr,x ) outw (x,addr)

#define out_be32(addr,x ) outl (x,addr)

#define outb_p(val, port) outb((val), (port))

#define outw_p(val, port) outw((val), (port))

#define outl_p(val, port) outl((val), (port))

4. Memory and IO port copy

#define memset_io(a,b,c) memset((void *)(a),(b),(c))

#define memcpy_fromio(a,b,c) memcpy((a),(void *)(b),(c))

#define memcpy_toio(a,b,c) memcpy((void *)(a),(b),(c))

When copying, the source address and destination address will automatically increase.

Example: Clear memory: memset_io(start,0,*size);

5. Batch read, read a string of bytes/words/long words

(source, destination, size)

static inline void io_insb (unsigned long port, void *dst, unsigned long count)

{

unsigned char *p = dst;

while (count--)

*p++ = inb (port);

}

static inline void io_insw (unsigned long port, void *dst, unsigned long count)

{

unsigned short *p = dst;

while (count--)

*p++ = inv(port);

}

static inline void io_insl (unsigned long port, void *dst, unsigned long count)

{

unsigned long *p = dst;

while (count--)

*p++ = inl(port);

}

#define insb(a,b,l) io_insb(a,b,l)

#define insw(a,b,l) io_insw(a,b,l)

#define insl(a,b,l) io_insl(a,b,l)

Example: insb(adr, data, size);

6. Batch write

(destination, source, size)

static inline void io_outsb (unsigned long port, const void *src, unsigned long count)

{

const unsigned char *p = src;

while (count--)

outb (*p++, port);

}

static inline void io_outsw (unsigned long port, const void *src, unsigned long count)

{

const unsigned short *p = src;

while (count--)

outw (*p++, port);

}

static inline void io_outsl (unsigned long port, const void *src, unsigned long count)

{

const unsigned long *p = src;

while (count--)

outl (*p++, port);

}

#define outsb(a,b,l) io_outsb(a,b,l)

#define outsw(a,b,l) io_outsw(a,b,l)

#define outsl(a,b,l) io_outsl(a,b,l)

Example: outsb(adr, data, size);

Reference address：iMX257 pin configuration function/memory read and write function

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