s3c2440uda1341驱动分析.docVIP

驱动架构： 驱动分两个层次，上层是平台设备驱动，底层是audio驱动与mixer驱动。（1）标准的平台设备驱动结构，probe与remove两个函数。probe：获得平台资源-申请内存区域-io内存重映射-获得并使能时钟-设置gpio口-初始化iis总线- 初始化uda1341-audio dma初始化-注册dsp和mixer-释放内存区域。代码及注释：static int s3c2410iis_probe(struct platform_device *pdev) {struct resource *res;unsigned long flags;int ret;DPRINTK(s3c2410iis_probe\n);//获得平台设备资源res = platform_get_resource(pdev, IORESOURCE_MEM, 0);if (res == NULL) {printk(KERN_INFO PFX failed to get memory region resouce\n);return -ENOENT;}//申请可用内存res = request_mem_region(res-start, RESSIZE(res), pdev-name);if(res == 0){printk(KERN_INFO PFX failed to request io memory region.\n);return -ENOENT;}//io内存重映射iis_base = ioremap(res-start, RESSIZE(res));if(iis_base == 0){printk(KERN_INFO PFX failed to ioremap() io memory region.\n); ret = -EINVAL;goto free_mem_region;}//获得时钟资源iis_clock = clk_get(pdev-dev, iis);if (iis_clock == NULL) {printk(KERN_INFO PFX failed to find clock source\n);return -ENOENT;}/*********************modify by lfc************************/clk_enable(iis_clock);//使能时钟/***********************end add*************************///禁用本地中断，gpio口设置，恢复中断local_irq_save(flags);/* GPB 4: L3CLOCK, OUTPUT */s3c2410_gpio_cfgpin(S3C2410_GPB4, S3C2410_GPB4_OUTP);s3c2410_gpio_pullup(S3C2410_GPB4,1);/* GPB 3: L3DATA, OUTPUT */s3c2410_gpio_cfgpin(S3C2410_GPB3,S3C2410_GPB3_OUTP);/* GPB 2: L3MODE, OUTPUT */s3c2410_gpio_cfgpin(S3C2410_GPB2,S3C2410_GPB2_OUTP);s3c2410_gpio_pullup(S3C2410_GPB2,1);/* GPE 3: I2SSDI */s3c2410_gpio_cfgpin(S3C2410_GPE3,S3C2410_GPE3_I2SSDI);s3c2410_gpio_pullup(S3C2410_GPE3,1);/* GPE 0: I2SLRCK */s3c2410_gpio_cfgpin(S3C2410_GPE0,S3C2410_GPE0_I2SLRCK);s3c2410_gpio_pullup(S3C2410_GPE0,1);/* GPE 1: I2SSCLK */s3c2410_gpio_cfgpin(S3C2410_GPE1,S3C2410_GPE1_I2SSCLK);s3c2410_gpio_pullup(S3C2410_GPE1,1);/* GPE 2: CDCLK */s3c2410_gpio_cfgpin(S3C2410_GPE2,S3C2410_GPE2_CDCLK);s3c2410_gpio_pullup(S3C2410_GPE2,1);/* GPE 4: I2SSDO */s3c2410_gpio_cfgpin(S3C2410_GPE4,S3C2410_GPE4_I2S