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研发客服要包含的三个头文件：
#include 'mx257_gpio.h'
#include 'mx25_pins.h'
#include 'iomux.h'
一、GPIO引脚使用
选择引脚模式->引脚配置->申请GPIO->设置引脚输入/输出->读取GPIO->释放引脚模式->
释放GPIO
1.选择引脚的模式(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)
示例： mxc_request_iomux(GPIO2_21, MUX_CONFIG_ALT5);
mxc_free_iomux(GPIO2_21, MUX_CONFIG_ALT5);
#define GPIO2_21 MX25_PIN_CLKO (定义在mx25_pin.h中)
2.设置引脚的配置
void mxc_iomux_set_pad(iomux_pin_name_t pin, u32 config)
示例: mxc_iomux_set_pad(GPIO2_21, 0);
#define GPIO2_21 MX25_PIN_CLKO (定义在mx25_pin.h中)
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.申请GPIO
int gpio_request(unsigned gpio, const char *label)
void gpio_free(unsigned gpio)
示例： gpio_request(IOMUX_TO_GPIO(GPIO2_21), 'GPIO2_21');
gpio_free(IOMUX_TO_GPIO(GPIO2_21));
4.设置引脚的输入输出模式：
相关文件：
/drivers/gpio/gpiolib.c
/arch/arm/plat-mxc/gpio.c
/arch/arm/plat-mxc/include/mach/gpio.h
输入：int gpio_direction_input(unsigned gpio)
示例：gpio_direction_input(IOMUX_TO_GPIO(GPIO2_21)); //设置GPIO2_21为输入模式
#define GPIO2_21 MX25_PIN_CLKO (定义在mx25_pin.h中)
输出：int gpio_direction_output(unsigned gpio, int value)
示例： gpio_direction_output(IOMUX_TO_GPIO(GPIO2_21), 0); // GPIO2_21输出0
gpio_direction_output(IOMUX_TO_GPIO(GPIO2_21), 1); // GPIO2_21输出1
5.获取引脚的值
int gpio_get_value(unsigned int gpio)
注意：每次读取引脚的值时，必须先设置gpio引脚为输入模式
示例： gpio_direction_input(IOMUX_TO_GPIO(GPIO3_15));
data = gpio_get_value(IOMUX_TO_GPIO(GPIO3_15));
相关文件：
arch/arm/plat-mxc/include/mach/gpio.h
drivers/gpio/gpiolib.c
arch/arm/plat-mxc/gpio.c
在gpio.h文件中
①定义了#define gpio_get_value __gpio_get_value(定义在 gpiolib.c中)
②在__gpio_get_value中调用chip->get，实际调用到的是 arch/arm/plat-mxc/gpio.c 文件中 mxc_gpio_get 函数
二、寄存器操作
1.内存映射、IO端口
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#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.读映射的内存、IO端口、读取字节端口(8bit)/字端口(16bit)/长字端口(32bit)
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#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; }) |
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#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)) |
或者：val = *((unsigned char*) (0xc00b0fe4));
io_mem = ioremap(0xfb000000,0x200000);
val = *((unsigned char*)(io_mem+0x100000));
3.写映射的内存、IO端口
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#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)) |
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#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.内存、IO端口拷贝
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#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)) |
拷贝时，源地址和目的地址会自动增长
示例：内存清零：memset_io(start,0,*size);
5.批量读取，读取一串字节/字/长字
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(源， 目的， 大小) 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++ = inw (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) |
示例：insb(adr, data, size);
6.批量写
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(目的，源 ， 大小) 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) |
示例： outsb(adr, data, size);