学步园

最近用mini2440学习linux驱动，做一下笔记

LED驱动：

static int __init dev_init(void)

在驱动的初始化函数中经常看到，__init 前缀，
这个在下面文件中定义

file:/include/linux/init.h

/* These macros are used to mark some functions or<br /> * initialized data (doesn't apply to uninitialized data)<br /> * as `initialization' functions. The kernel can take this<br /> * as hint that the function is used only during the initialization<br /> * phase and free up used memory resources after<br /> *<br /> * Usage:<br /> * For functions:<br /> *<br /> * You should add __init immediately before the function name, like:<br /> *<br /> * static void __init initme(int x, int y)<br /> * {<br /> * extern int z; z = x * y;<br /> * }

主要是将这个函数放在init段section中，这样可以在执行完成后，释放内存。

关于s3c2410_gpio_cfgpin函数，只能了解到，设置某个GPIO的功能，但是怎么实现的没看明白，好像还用到虚拟地址了，最后也没有发现是怎么配置的GPCON寄存器的，

void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function)<br /> {<br /> void __iomem *base = S3C24XX_GPIO_BASE(pin);<br /> unsigned long mask;<br /> unsigned long con;<br /> unsigned long flags;<br /> if (pin < S3C2410_GPIO_BANKB) {<br /> mask = 1 << S3C2410_GPIO_OFFSET(pin);<br /> } else {<br /> mask = 3 << S3C2410_GPIO_OFFSET(pin)*2;<br /> }<br /> switch (function) {<br /> case S3C2410_GPIO_LEAVE:<br /> mask = 0;<br /> function = 0;<br /> break;<br /> case S3C2410_GPIO_INPUT:<br /> case S3C2410_GPIO_OUTPUT:<br /> case S3C2410_GPIO_SFN2:<br /> case S3C2410_GPIO_SFN3:<br /> if (pin < S3C2410_GPIO_BANKB) {<br /> function -= 1;<br /> function &= 1;<br /> function <<= S3C2410_GPIO_OFFSET(pin);<br /> } else {<br /> function &= 3;<br /> function <<= S3C2410_GPIO_OFFSET(pin)*2;<br /> }<br /> }<br /> /* modify the specified register wwith IRQs off */<br /> local_irq_save(flags);<br /> con = __raw_readl(base + 0x00);<br /> con &= ~mask;<br /> con |= function;<br /> __raw_writel(con, base + 0x00);<br /> local_irq_restore(flags);<br /> }<br />

而且，后面

有个地方讲不通：

（这个地方应该是都不满足
switch
的条件，所以，
function
不改变）

#define
S3C2410_GPIO_LEAVE  
(0xFFFFFFFF)

#define S3C2410_GPIO_INPUT  
(0xFFFFFFF0) 
/*
not available on A */

#define
S3C2410_GPIO_OUTPUT 
(0xFFFFFFF1)

#define
S3C2410_GPIO_IRQ    
(0xFFFFFFF2)  
/* not available for all */

#define
S3C2410_GPIO_SFN2   
(0xFFFFFFF2) 
/* bank A => addr/cs/nand */

#define
S3C2410_GPIO_SFN3   
(0xFFFFFFF3) 
/* not available on A */

而

#define
S3C2410_GPB5_OUTP   
(0x01 << 10)

所以，

s3c2410_gpio_cfgpin(S3C2410_GPB5, S3C2410_GPB5_OUTP);

switch (function)

根本对不上号？

s3c2410_gpio_cfgpin(S3C2410_GPB5, S3C2410_GPB5_OUTP);

s3c2410_gpio_cfgpin(37, S3C2410_GPB5_OUTP);

s3c2410_gpio_cfgpin(37,

 0x01 << 10


);

剩下的37怎么变换出mask，怎么得到GPCON的地址没看懂？

这个在
/arch/arm/mach-s3c2410/include/mach/regs-gpio.h
中定义

#define
S3C2410_GPB5        
S3C2410_GPIONO(S3C2410_GPIO_BANKB, 5)

#define
S3C2410_GPB5_INP     (0x00 << 10)

#define
S3C2410_GPB5_OUTP    (0x01 << 10)

#define
S3C2410_GPB5_nXBACK  (0x02 << 10)

S3C2410_GPIONO

(S3C2410_GPIO_BANKB
,
5)

#define S3C2410_GPIONO

(bank,offset) ((bank) + (offset))

#define
S3C2410_GPIO_BANKA   (32*0)

#define S3C2410_GPIO_BANKB

  
(32*1)

可以看一下这篇文章：

http://www.linuxidc.com/Linux/2011-06/37322.htm