linux内核gpio操作函数解析.doc

详解内核驱动操作GPIO引脚API函数函数原型：void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function)；unsigned int s3c2410_gpio_getcfg(unsigned int pin)；void s3c2410_gpio_pullup(unsigned int pin, unsigned int to)；void s3c2410_gpio_setpin(unsigned int pin, unsigned int to)；unsigned int s3c2410_gpio_getpin(unsigned int pin)；unsigned int s3c2410_modify_misccr(unsigned int clear, unsigned int change)；int s3c2410_gpio_getirq(unsigned int pin)；关于函数中用到的虚拟地址到物理地址转换的变量及算法可以参考/hefeng330467115126/blog/static/782058422010620511659/或/u3/102836/showart_2065945.html看简单led驱动程序是用到的文件及头文件可能有：linux/include/asm-arm/arch-s3c2410/map.hlinux/include/asm-arm/arch-s3c2410/regs-gpio.hlinux/arch/arm/plat-s3c24xx/gpio.clinux/include/asm-arm/io.h用Source Insight 打开这些文件，然后再看驱动程序，可以随意跳转到定义处，很是方便pin参数：gpio引脚及特殊功能寄存器助记符都在linux/include/asm-arm/arch-s3c2410/regs-gpio.h中定义：eg:S3C2410_GPACON S3C2410_GPADATS3C2410_GPA0 - S3C2410_GPA22 /引脚S3C2410_GPA0_OUT - S3C2410_GPA22_OUT /设置引脚为输出用到哪个不清楚的可以直接到这个文件去查找还有中断和GSTATUS：S3C2410_EXTINT0 - irq sense control for EINT0.EINT7S3C2410_EXTINT1 - irq sense control for EINT8.EINT15S3C2410_EXTINT2 - irq sense control for EINT16.EINT23function参数：指定引脚功能：输出、输入还是特殊功能，也在linux/include/asm-arm/arch-s3c2410/regs-gpio.h中定义。函数功能：1 原型：void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function)；作用：配置GPIO引脚功能，即是配置相应的CON位eg： s3c2410_gpio_cfgpin(S3C2410_GPB0, S3C2410_GPB0_OUTP)；/设置B5脚为输出功能函数原代码及注释：（这个函数注释的比较详细，后面类似的不再重复注释）void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function)void _iomem *base = S3C24XX_GPIO_BASE(pin); /取引脚基地址即是：GPA0、GPB0 的虚拟基地址unsigned long mask; unsigned long con;unsigned long flags;if (pin S3C2410_GPIO_BANKB) mask = 1 S3C2410_GPIO_OFFSET(pin);/用于查找对应的引脚位（端口A一位控制一个引脚） else mask = 3 S3C2410_GPIO_OFFSET(pin)*2;/除端口A外其他端口都是两位控制一个引脚/根据function值具体确定怎么来调整functionswitch (function) case S3C2410_GPIO_LEAVE:mask = 0;function = 0;break;case S3C2410_GPIO_INPUT:case S3C2410_GPIO_OUTPUT:case S3C2410_GPIO_SFN2:case S3C2410_GPIO_SFN3:if (pin S3C2410_GPIO_BANKB) / 当某位被设为0时，相应引脚为输出，此时可function -= 1; /以在GPADAT中相应位写入1或0；当某位被function &= 1; /设为1时，相应引脚为地址线或用于地址控制。function = S3C2410_GPIO_OFFSET(pin); /偏移量即是相应的引脚位 else function &= 3;function = S3C2410_GPIO_OFFSET(pin)*2; /除A端口以外的其他端口都是 /两位控制一个引脚/* modify the specified register wwith IRQs off */local_irq_save(flags); /调用该宏函数来保存IRQ 中断使能状态，并禁止IRQ 中断con = _raw_readl(base + 0x00);/ 基地址加偏移量得到相应端口的控制寄存器（GPxCON）地址，然后读取该寄存器的值 con &= mask; / 找到需要修改的引脚的控制位 con |= function; / 使对应的引脚的功能为function_raw_writel(con, base + 0x00); / 重写控制寄存器的值，实现引脚功能修改local_irq_restore(flags); /恢复IRQ 和FIQ 的中断使能状态2 原型：unsigned int s3c2410_gpio_getcfg(unsigned int pin)；作用：该函数根据引脚获得指定引脚配置的功能值eg： s3c2410_gpio_getcfg (S3C2410_GPB5)；/读取B5脚为的配置功能 输入00、输出01、特殊功能02 函数原代码及注释：unsigned int s3c2410_gpio_getcfg(unsigned int pin)void _iomem *base = S3C24XX_GPIO_BASE(pin);unsigned long val = _raw_readl(base);if (pin = S3C2410_GPIO_OFFSET(pin);val &= 1;val += 1; else val = S3C2410_GPIO_OFFSET(pin)*2;val &= 3;return val | S3C2410_GPIO_INPUT;3 原型：void s3c2410_gpio_pullup(unsigned int pin, unsigned int to)；作用:设置相应GPIO口的上拉电阻eg s3c2410_gpio_pullup（S3C2410_GPB5，0）/设置S3C2410GPB5不要上拉电阻s3c2410_gpio_pullup（S3C2410_GPB5，1）/设置S3C2410GPB5要上拉电阻函数原代码及注释：void s3c2410_gpio_pullup(unsigned int pin, unsigned int to)void _iomem *base = S3C24XX_GPIO_BASE(pin);unsigned long offs = S3C2410_GPIO_OFFSET(pin);unsigned long flags;unsigned long up;if (pin S3C2410_GPIO_BANKB)return;local_irq_save(flags);up = _raw_readl(base + 0x08); / /0x08是GPxUP寄存器的物理偏移量up &= (1L offs); up |= to offs;_raw_writel(up, base + 0x08);local_irq_restore(flags);4原型：void s3c2410_gpio_setpin(unsigned int pin, unsigned int to)；作用：该函数给指定的引脚位写入0或1，即是配置相应的DAT位。egs3c2410_gpio_setpin (S3C2410_GPB5 ,0)；/设置S3C2410GPB5的输出值为0s3c2410_gpio_setpin (S3C2410_GPB5 ,1)；/设置S3C2410GPB5的输出值为1函数原代码及注释：void s3c2410_gpio_setpin(unsigned int pin, unsigned int to)void _iomem *base = S3C24XX_GPIO_BASE(pin);unsigned long offs = S3C2410_GPIO_OFFSET(pin);unsigned long flags;unsigned long dat;local_irq_save(flags);dat = _raw_readl(base + 0x04); /0x04是GPxDAT寄存器的物理偏移量dat &= (1 offs);dat |= to offs;_raw_writel(dat, base + 0x04);local_irq_restore(flags);5原型：void s3c2410_gpio_getpin(unsigned int pin)；作用：该函数读取指定引脚的状态 返回0或 1，即是读取相应的DAT位。egs3c2410_gpio_setpin (S3C2410_GPB5 )；/ 读取S3C2410GPB5位的状态。函数原代码及注释：unsigned int s3c2410_gpio_getpin(unsigned int pin)void _iomem *base = S3C24XX_GPIO_BASE(pin);unsigned long offs = S3C2410_GPIO_OFFSET(pin);return _raw_readl(base + 0x04) & (1 offs);6原型：unsigned int s3c2410_modify_misccr(unsigned int clear, unsigned int change)；作用：