值得参考的一篇linux gpio

LINUX ARM平台的GPIO2011-04-20 20:21:35|  分类： 默认分类 |  标签：define  pin  unsigned  int  0x10     字号：大中小 订阅首先是代码中的几个宏定义： 2.6.31内核：arch/arm/mach-2410/include/mach/regs-gpio.h #define S3C2410_GPIONO(bank,offset) ((bank) + (offset)) #define S3C2410_GPIO_BANKA (32*0)#define S3C2410_GPIO_BANKB (32*1)#define S3C2410_GPIO_BANKC (32*2).... #define S3C2410_GPIO_BASE(pin) ((((pin) & ~31) >> 1) + S3C24XX_VA_GPIO)#define S3C2410_GPIO_OFFSET(pin) ((pin) & 31) #define S3C2410_GPBCON S3C2410_GPIOREG(0x10)#define S3C2410_GPBDAT S3C2410_GPIOREG(0x14)#define S3C2410_GPBUP S3C2410_GPIOREG(0x18) /* no i/o pin in port b can have value 3! */ #define S3C2410_GPB0 S3C2410_GPIONO(S3C2410_GPIO_BANKB, 0)#define S3C2410_GPB0_INP (0x00 0)#define S3C2410_GPB0_OUTP (0x01 0)#define S3C2410_GPB0_TOUT0 (0x02 0) #define S3C2410_GPB1 S3C2410_GPIONO(S3C2410_GPIO_BANKB, 1)#define S3C2410_GPB1_INP (0x00 2)#define S3C2410_GPB1_OUTP (0x01 2)#define S3C2410_GPB1_TOUT1 (0x02 2)....driver中有这样的代码：s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);s3c2410_gpio_setpin(led_table[i], 1);其中static unsigned long led_table [] = {S3C2410_GPB5,S3C2410_GPB6,S3C2410_GPB7,S3C2410_GPB8,};static unsigned int led_cfg_table [] = {S3C2410_GPB5_OUTP,S3C2410_GPB6_OUTP,S3C2410_GPB7_OUTP,S3C2410_GPB8_OUTP,};  2.6.31内核：arch/arm/plat-s3c24xx/gpio.c： void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function){void __iomem *base = S3C2410_GPIO_BASE(pin);unsigned long mask;unsigned long con;unsigned long flags; if (pinmask = 1 S3C2410_GPIO_OFFSET(pin);} else {mask = 3 S3C2410_GPIO_OFFSET(pin)*2;} local_irq_save(flags); con = __raw_readl(base + 0x00);con &= ~mask;con |= function; __raw_writel(con, base + 0x00); //config the GPXCON local_irq_restore(flags);} EXPORT_SYMBOL(s3c2410_gpio_cfgpin);  void s3c2410_gpio_setpin(unsigned int pin, unsigned int to){void __iomem *base = S3C2410_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);dat &= ~(1dat |= to__raw_writel(dat, base + 0x04); //config the GPXDAT local_irq_restore(flags);} EXPORT_SYMBOL(s3c2410_gpio_setpin);===========================================================================================================对传给s3c2410_gpio_cfgpin 函数的pin参数由来解释：pin就是如S3C2410_GPB0（表示B组第五个端口），S3C2410_GPA0之类的宏，而这些宏表示着什么呢？如宏S3C2410_GPB0就是通过宏#define S3C2410_GPB0 S3C2410_GPIONO(S3C2410_GPIO_BANKB, 0)得到的，S3C2410_GPIONO(S3C2410_GPIO_BANKB, 0)宏是这样定义的#define S3C2410_GPIONO(bank,offset) ((bank) + (offset))很明显，S3C2410_GPIONO(S3C2410_GPIO_BANKB, 0)就是计算两个参数的和，第一个参数表示第几组，第二个参数0表示0端口，如果是计算第一个端口的话，第二个参数就是1；对于S3C2410_GPIO_BANKB宏的定义是#define S3C2410_GPIO_BANKB (32*1)而类似GPA的定义是#define S3C2410_GPIO_BANKA (32*0)所以最后算出来的S3C2410_GPB5的值是：37 = S3C2410_GPIO_BANKB + 5=32*1 + 5； ===========================================================================================================关于s3c2410_gpio_cfgpin的第二个参数function其实是由宏定义的，如#define S3C2410_GPB0_INP (0x00 0)#define S3C2410_GPB0_OUTP (0x01#define S3C2410_GPB0_TOUT0 (0x02#define S3C2410_GPB1_INP (0x00 2)#define S3C2410_GPB1_OUTP (0x01#define S3C2410_GPB1_TOUT1 (0x02他们是用来设置端口的功能的，就是设置GPACON、GPBCON、GPCCON、GPDCON等配置寄存器的，因为端口0的设置位占了两位，而端口1的设置为是紧接着的第3，4位（没有第0位的说法），所以要移2位。 =========================================================================================================== A   有个GPIO的虚拟地址base,接下来分析下面的：#define S3C2410_GPIO_BASE(pin) ((((pin) & ~31) >> 1) + S3C24XX_VA_GPIO)关于((pin) & ~31) >> 1)的计算：由上面算出的宏S3C2410_GPB5值37（既是pin值）来计算出((pin) & ~31) >> 1)的值，因为pin = S3C2410_GPB5 = 37， 37 的二进制是10,0101，~31的二进制是10,0000所以(pin) & ~31) 的值是 32（0x20），((pin) & ~31) >> 1)的结果是16（0x10），其实无论是B组内的第几个端口，如果是B组端口的话， ((pin) & ~31) >> 1)的结果都是16（0x10），这就是S3C2410_GPIO_BASE(pin)的功能，即算出端口的基地址，~31主要是为了清除S3C2410_GPB5的后5位。B    相对于#define S3C2410_GPIO_BASE(pin) ((((pin) & ~31) >> 1) + S3C24XX_VA_GPIO)有个#define S3C2410_GPIO_OFFSET(pin) ((pin) & 31)对比这两个宏，宏S3C2410_GPIO_OFFSET(pin)功能很明显了：计算出是组内的端口号，如S3C2410_GPB5算出的就是5了。===========================================================================================================关于S3C2410芯片的S3C24XX_VA_GPIO的计算#define S3C24XX_VA_GPIO ((S3C24XX_PA_GPIO - S3C24XX_PA_UART) + S3C24XX_VA_UART)#define S3C24XX_PA_GPIO     S3C2410_PA_GPIO#define S3C2410_PA_GPIO (0x56000000)#define S3C24XX_PA_UART S3C2410_PA_UART#define S3C2410_PA_UART (0x50000000) #define S3C24XX_VA_UART        S3C_VA_UART#define S3C_VA_UART        S3C_ADDR(0x01000000)    /* UART */#define S3C_ADDR(x)        ((void __iomem __force *)S3C_ADDR_BASE + (x))#define S3C_ADDR(x)        (S3C_ADDR_BASE + (x))#define S3C_ADDR_BASE      (0xF4000000)S3C24XX_VA_GPIO的结果是0xFB000000 = 0x56000000 - 0x50000000 + 0xF4000000 + 0x01000000以上的宏是在2.6.31内核的。===========================================================================================================以下是一些访问通用I/O的方法：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)；int s3c2410_gpio_getpull(unsigned int pin)；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)；=========================================================================================================== 有以上对宏define S3C2410_GPIO_BASE(pin)的解释，可推断出GPA基地址的是0x0+S3C24XX_VA_GPIO,GPB是0x10+S3C24XX_VA_GPIO,GPC是 0x20+S3C24XX_VA_GPIO...为什么相邻的端口组地址相差0x10呢？因为每一组端口都有四个寄存器，举GPA和GPB例子：GPA:RegisterAddressR/W        DescriptionReset ValueGPACON0x56000000  R/WConfigures the pins of port A0xffffffGPADAT0x56000004   R/WThe data register for port AUndef.Reserved0x56000008    - Reserved UndefReserved0x5600000c    - Reserved UndefGPB:RegisterAddressR/WDescriptionReset ValueGPBCON0x56000010R/WConfigures the pins of port B0x0GPBDAT0x56000014R/WThe data register for port B.UndefGPBUP0x56000018R/Wpull-up disable register for port B0x0Reserved0x5600001c   由上两个表可知：每组四个寄存器是为了方便起见，组内相邻的寄存器之间相差4个字节，既是4*8=32bit，组与组之间相差0x10个字节。==================================================================================================关于宏#define S3C2410_GPBCON     S3C2410_GPIOREG(0x10)#define S3C2410_GPBDAT      S3C2410_GPIOREG(0x14)#define S3C2410_GPBUP       S3C2410_GPIOREG(0x18)#define S3C2410_GPCCON        S3C2410_GPIOREG(0x20)#define S3C2410_GPCDAT         S3C2410_GPIOREG(0x24)#define S3C2410_GPCUP        S3C2410_GPIOREG(0x28)而S3C2410_GPIOREG的定义是：#define S3C2410_GPIOREG(x) ((x) + S3C24XX_VA_GPIO)所以而GPBCON0x56000010GPBDAT0x56000014========================================================================================================== 其实想想这代码也不难理解，只是宏定义和函数的实现分散在kernel包的各个文件内，因此不太容易寻找。线索齐了后，就一目了然了。  转载请说明出处：http://blog.163.com/yjie_life/blog/static/163198337201132082135276/