GPIO（GeneralPurpose Input/Output的缩写）便是芯片的引脚，引脚是可编程的可对引脚的作业形式进行设置：输入形式(检测输入信号)，输出形式(输出0或1)，高阻状况(常用于AD转化)，还有制止或答应上内部下拉电阻(上拉：管脚经过电阻接高电平，下拉：管脚经过电阻接地，也能够外部接上拉或下拉电阻)，还有管脚复用等功用，即经过对内部寄存器的设置使引脚既能够作业在一般形式，作为一般的GPIO口运用，也能够作业在特别形式，比方作为外部中止信号输入引脚等等。假如不设置GPIO引脚，CPU作业时有一个初始化形式，能够从datasheet（芯片手册）上了解。对GPIO的操控是编写驱动程序最常见和重要的一项作业内容。在Linux内核代码中，现已供给了针对三星S3C2410/S3C2440等芯片GPIO的操控。
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linux-2.6.30.4\arch\arm\plat-s3c\include\plat\ map-base.h
#defineS3C_ADDR_BASE (0xF4000000)
#ifndef __ASSEMBLY__
#define S3C_ADDR(x) ((void__iomem __force *)S3C_ADDR_BASE+ (x))
#else
#defineS3C_ADDR(x) (S3C_ADDR_BASE+ (x))
#endif
#define S3C_VA_IRQ S3C_ADDR(0x00000000) /* irq controller(s) */
#define S3C_VA_SYS S3C_ADDR(0x00100000) /* system control */
#define S3C_VA_MEM S3C_ADDR(0x00200000) /* system control */
#define S3C_VA_TIMER S3C_ADDR(0x00300000) /* timer block */
#define S3C_VA_WATCHDOG S3C_ADDR(0x00400000) /* watchdog */
#define S3C_VA_UART S3C_ADDR(0x01000000) /*UART */
linux-2.6.30.4\arch\arm\plat-s3c24xx\include\plat\ map.h
/* UARTs */
#defineS3C24XX_VA_UART S3C_VA_UART
#define S3C2410_PA_UART (0x50000000)
#define S3C24XX_SZ_UART SZ_1M
#define S3C_UART_OFFSET (0x4000)
UART映射后的虚拟地址是0xF4000000＋0x01000000
linux-2.6.30.4\arch\arm\plat-s3c24xx\include\plat\ map.h
/* GPIO ports */
#define S3C2410_PA_GPIO (0x56000000)
#defineS3C24XX_VA_GPIO ((S3C24XX_PA_GPIO- S3C24XX_PA_UART) + S3C24XX_VA_UART)//GPIO的虚拟地址
#define S3C24XX_SZ_GPIO SZ_1M
GPIO的基地址为 0xfb000000
S3C24XX_VA_GPIO在不同的linux版别中或许不一样，2.6.30.4是依照上面的办法，下图是2.6.22.6的完成办法
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linux/include/asm-arm/arch-s3c2410/map.h #ifndef __ASSEMBLY__ #define S3C2410_ADDR(x) ((void __iomem *)0xF0000000 + (x)) #else #define S3C2410_ADDR(x) (0xF0000000 + (x)) #endif #define S3C2400_ADDR(x) S3C2410_ADDR(x) /* GPIO ports */ #define S3C24XX_VA_GPIO S3C2410_ADDR(0x00E00000) #define S3C2400_PA_GPIO (0x15600000) #define S3C2410_PA_GPIO (0x56000000) #define S3C24XX_SZ_GPIO SZ_1M |
arch/arm/mach-s3c2410/include/mach/regs-gpio.h
#defineS3C2410_GPIOREG(x) ((x) + S3C24XX_VA_GPIO)//在GPIO的虚拟地址上直接偏移
#define S3C24XX_GPIOREG2(x) ((x) + S3C24XX_VA_GPIO2)
linux-2.6.30.4/arch/arm/mach-s3c2410/include/mach/gpio-nrs.h
#defineS3C2410_GPIONO(bank,offset)((bank) + (offset))
#defineS3C2410_GPIO_BANKA (32*0)//每组最多32个端口
#define S3C2410_GPIO_BANKB(32*1)
#define S3C2410_GPIO_BANKC(32*2)
#define S3C2410_GPIO_BANKD(32*3)
#define S3C2410_GPIO_BANKE(32*4)
#define S3C2410_GPIO_BANKF(32*5)
#define S3C2410_GPIO_BANKG(32*6)
#define S3C2410_GPIO_BANKH (32*7)
arch/arm/mach-s3c2410/include/mach/regs-gpio.h
#defineS3C2410_GPACON S3C2410_GPIOREG(0x00)//A组GPIO的操控寄存器
#define S3C2410_GPADAT S3C2410_GPIOREG(0x04)//A组GPIO的数据寄存器
#define S3C2400_GPACON S3C2410_GPIOREG(0x00)
#define S3C2400_GPADAT S3C2410_GPIOREG(0x04)
#defineS3C2410_GPA0 S3C2410_GPIONO(S3C2410_GPIO_BANKA, 0)//A组GPIO的第0个的pin数
#define S3C2410_GPA0_OUT(0<<0)//设置A0为输出功用
#define S3C2410_GPA0_ADDR0(1<<0)//设置A0作为地址线ADDR0
*******************************************************************************
#define S3C2410_GPBCON S3C2410_GPIOREG(0x10)
#define S3C2410_GPBDAT S3C2410_GPIOREG(0x14)
#define S3C2410_GPBUP S3C2410_GPIOREG(0x18)
#define S3C2410_GPB0S3C2410_GPIONO(S3C2410_GPIO_BANKB, 0)
#define S3C2410_GPB0_INP(0x00 << 0)
#define S3C2410_GPB0_OUTP(0x01 << 0)
#define S3C2410_GPB0_TOUT0(0x02 << 0)
#define S3C2400_GPB0_DATA16(0x02 << 0)
*******************************************************************************
#define S3C2410_GPCCON S3C2410_GPIOREG(0x20)
#define S3C2410_GPCDAT S3C2410_GPIOREG(0x24)
#define S3C2410_GPCUP S3C2410_GPIOREG(0x28)
#define S3C2410_GPC0S3C2410_GPIONO(S3C2410_GPIO_BANKC, 0)
#define S3C2410_GPC0_INP (0x00<< 0)
#define S3C2410_GPC0_OUTP (0x01<< 0)
#define S3C2410_GPC0_LEND (0x02<< 0)
#define S3C2400_GPC0_VD0 (0x02<< 0)
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#define S3C2410_GPDCON S3C2410_GPIOREG(0x30)
#define S3C2410_GPDDAT S3C2410_GPIOREG(0x34)
#define S3C2410_GPDUP S3C2410_GPIOREG(0x38)
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— Port A(GPA): 25-output port — Port B(GPB): 11-input/out port — Port C(GPC): 16-input/output port — Port D(GPD): 16-input/output port — Port E(GPE): 16-input/output port — Port F(GPF): 8-input/output port — Port G(GPG): 16-input/output port — Port H(GPH): 9-input/output port — Port J(GPJ): 13-input/output port Register Address R/W Description Reset Value GPACON 0x56000000 R/W Configures the pins of port A 0xffffff GPADAT 0x56000004 R/W The data register for port A Undef. Reserved 0x56000008 – Reserved Undef Reserved 0x5600000c – Reserved Undef Register Address R/W Description Reset Value GPBCON 0x56000010 R/W Configures the pins of port B 0x0 GPBDAT 0x56000014 R/W The data register for port B Undef. GPBUP 0x56000018 R/W Pull-up disable register for port B 0x0 Reserved 0x5600001c Register Address R/W Description Reset Value GPCCON 0x56000020 R/W Configures the pins of port C 0x0 GPCDAT 0x56000024 R/W The data register for port C Undef. GPCUP 0x56000028 R/W Pull-up disable register for port C 0x0 Reserved 0x5600002c – – – Register Address R/W Description Reset Value GPDCON 0x56000030 R/W Configures the pins of port D 0x0 GPDDAT 0x56000034 R/W The data register for port D Undef. GPDUP 0x56000038 R/W Pull-up disable register for port D 0xf000 Reserved 0x5600003c – – – |
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void s3c2410_gpio_cfgpin(unsignedint pin, unsigned int function)// 其间参数pin是要装备的GPIO引脚，参数function是要装备的功用
{
void __iomem *base = S3C24XX_GPIO_BASE(pin);
unsignedlong mask;
unsignedlong con;
unsignedlong flags;
if(pin < S3C2410_GPIO_BANKB){
mask= 1 << S3C2410_GPIO_OFFSET(pin);
}else {
mask= 3 << S3C2410_GPIO_OFFSET(pin)*2;
}
//假如引脚为A端口之外GPIO端口时，它是用两位来装备详细的引脚，故掩码为2位
switch(function) {
caseS3C2410_GPIO_LEAVE:
mask= 0;
function= 0;
break;
caseS3C2410_GPIO_INPUT:
caseS3C2410_GPIO_OUTPUT:
caseS3C2410_GPIO_SFN2:
caseS3C2410_GPIO_SFN3:
if(pin < S3C2410_GPIO_BANKB){
function-= 1;
function&= 1;
function<<= S3C2410_GPIO_OFFSET(pin);
}else {
function&= 3;
function<<= S3C2410_GPIO_OFFSET(pin)*2;
}
}
/* modify thespecified register wwith IRQs off */
local_irq_save(flags);// 关中止
con= __raw_readl(base + 0x00);
con &= ~mask;
con |= function;
__raw_writel(con, base + 0x00);
local_irq_restore(flags);// 开中止
}
arch/arm/mach-s3c2410/include/mach/regs-gpio.h
#define S3C2410_GPIO_BASE(pin)((((pin) & ~31) >> 1) + S3C24XX_VA_GPIO)
//每组GPIO的虚拟基地址（要先屏蔽最低的5位）依据端口编号pin，算出端口地点组的虚拟基址。((pin) & ~31)是去掉pin傍边小于等于31的零头(清0低5位)，>>1的原因是每组GPIO中最多能够有32个端口，操控这些端口需求4个寄存器空间，4个寄存器空间就需求4*4=16个字节进行编址，32/16=2，左移一位刚好满意。也便是说，上一组端口和下一组端口的编号相差32，而操控寄存器的地址相差16。
#define S3C2410_GPIO_OFFSET(pin) ((pin) & 31)
//依据端口编号pin，算出端口地点组的偏移量。((pin) & 31)即去掉比31大的数
linux/arch/arm/plat-s3c24xx/gpio.c
s3c2410_gpio_cfgpin //装备端口的GPIO的功用
s3c2410_gpio_getcfg//读取功用装备
s3c2410_gpio_pullup//装备上拉电阻
s3c2410_modify_misccr //杂项装备
s3c2410_gpio_getirq//给定端口，转化出IRQ号
s3c2410_gpio_irqfilter//装备IRQ过滤使能与否
s3c2410_gpio_setpin//写数据到端口
s3c2410_gpio_getpin//从端口读数据
以下代码摘自Leds的驱动程序，旨在阐明linux下怎么拜访寄存器
static unsigned long led_table [] =
{
S3C2410_GPB5,
S3C2410_GPB6,
S3C2410_GPB7,
S3C2410_GPB8,
};
/* 用来指定GPIO引脚的功用：输出 */
static unsigned int led_cfg_table [] =
{
S3C2410_GPB5_OUTP,
S3C2410_GPB6_OUTP,
S3C2410_GPB7_OUTP,
S3C2410_GPB8_OUTP,
};
static int gt2440_leds_ioctl(
structinode *inode,
structfile *file,
unsignedint cmd,
unsignedlong arg)
{
if(arg > 4)
{
return-EINVAL;
}
switch(cmd)
{
caseIOCTL_LED_ON:
//设置指定引脚的输出电平为0
s3c2410_gpio_setpin(led_table[arg], 0);
return0;
caseIOCTL_LED_OFF:
//设置指定引脚的输出电平为1
s3c2410_gpio_setpin(led_table[arg], 1);
return0;
default:
return-EINVAL;
}
}
static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.ioctl = gt2440_leds_ioctl,
};
static struct miscdevice misc = {
.minor= MISC_DYNAMIC_MINOR,
.name= DEVICE_NAME,
.fops= &dev_fops,
};
static int __init dev_init(void)
{
intret;
inti;
for(i = 0; i < 4; i++)
{
s3c2410_gpio_cfgpin(led_table[i],led_cfg_table[i]);
s3c2410_gpio_setpin(led_table[i],0);// 设置相应GPIO口的值
}
ret= misc_register(&misc);
printk(DEVICE_NAME” initialized\n”);
returnret;
}
static void __exit dev_exit(void)
{
misc_deregister(&misc);
}
module_init(dev_init);
module_exit(dev_exit); *******************************************************************************
