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麻烦朋友解释下LINUX的虚拟地址到物理地址的映射问题,我正在看一个蜂鸣器的驱动,
看到下面这个函数
static void PWM_Set_Freq( unsigned long freq )
{
unsigned long tcon;
unsigned long tcnt;
unsigned long tcfg1;
unsigned long tcfg0;
struct clk *clk_p;
unsigned long pclk;
/ / GPB0 as tout0, pwm output
s3c2410_gpio_cfgpin(S3C2410_GPB0, S3C2410_GPB0_TOUT0);
printk (KERN_INFO "\tS3C2410_TCON =0x%x\n",S3C2410_TCON);
tcon = __raw_readl(S3C2410_TCON);
tcfg1 = __raw_readl(S3C2410_TCFG1);
tcfg0 = __raw_readl(S3C2410_TCFG0);
//prescaler = 50
tcfg0 &= ~S3C2410_TCFG_PRESCALER0_MASK;
tcfg0 |= (50 - 1);
//mux = 1/16
tcfg1 &= ~S3C2410_TCFG1_MUX0_MASK;
tcfg1 |= S3C2410_TCFG1_MUX0_DIV16;
__raw_writel(tcfg1, S3C2410_TCFG1);
__raw_writel(tcfg0, S3C2410_TCFG0);
clk_p = clk_get(NULL, "pclk");
pclk = clk_get_rate(clk_p);
tcnt = (pclk/50/16)/freq;
__raw_writel(tcnt, S3C2410_TCNTB(0));
__raw_writel(tcnt/2, S3C2410_TCMPB(0));
tcon &= ~0x1f;
tcon |= 0xb; //disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 0
__raw_writel(tcon, S3C2410_TCON);
tcon &= ~2; //clear manual update bit
__raw_writel(tcon, S3C2410_TCON);
}
其中的
tcon = __raw_readl(S3C2410_TCON);
tcfg1 = __raw_readl(S3C2410_TCFG1);
tcfg0 = __raw_readl(S3C2410_TCFG0);
用到的虚拟地址S3C2410_TCON,S3C2410_TCFG0,S3C2410_TCFG1是怎么映射到实际的物理地址的,拜托知道的朋友解说解说,先谢谢了 |
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