DMA驱动框架
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框架入口源文件：dma.c
（可根据入口源文件，再按着框架到内核走一遍）
内核版本：linux_2.6.22.6 硬件平台：JZ2440
以下是驱动框架：
以下是驱动代码 dma.c ：
#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/irq.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h> #include <linux/poll.h> #include <linux/dma-mapping.h> //源地址 static unsigned char *src; static unsigned int src_phy; //目的地址 static unsigned char* dest; static unsigned int dest_phy; //空间大小 #define DMA_SIZE (1204*512) //驱动类 static struct class *dma_class; //主设备号 static int major ; #define USE_DMA 1 #define NO_DMA 0 //DMA寄存器 static struct s3c_dma_reg { unsigned long disrc; unsigned long disrcc; unsigned long didst; unsigned long didstc; unsigned long dcon; unsigned long dstat; unsigned long dcsrc; unsigned long dcdst; unsigned long dmaskting; }*s3c_dma_regs; //DMA地址 static unsigned long dma_addr0 = 0x4b000000; static unsigned long dma_addr1 = 0x4b000040; static unsigned long dma_addr2 = 0x4b000080; static unsigned long dma_addr3 = 0x4b0000c0; //为这个进程创建等待队列 static DECLARE_WAIT_QUEUE_HEAD(dma_wait_queue); //进程队列标志位 static volatile int dma_wait_queue_condition=0; static int s3c_dma_iotcl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long args) { int i=0; memset(src, 0xAA, DMA_SIZE); memset(dest, 0x55, DMA_SIZE); switch(cmd) { case NO_DMA : { for(i=0;i<DMA_SIZE;i++) dest[i] = src[i]; if(memcmp(src,dest,DMA_SIZE) == 0) printk("copy without DMA successfuly ! "); else printk("copy without DMA fialed ! "); break; } case USE_DMA : { // 设置DMA寄存器 s3c_dma_regs->disrc = src_phy; s3c_dma_regs->disrcc = (0<<0)|(0<<0); s3c_dma_regs->didst = dest_phy; s3c_dma_regs->didstc =(0<<3)|(0<<1)|(0<<0); s3c_dma_regs->dcon = (1<<30)|(1<<29)|(0<<28)|(1<<27)|(0<<23)|(0<<20)|(DMA_SIZE<<0); s3c_dma_regs->dmaskting = (1<<1)|(1<<0); //休眠进程 dma_wait_queue_condition = 0; //状态标志位为假 休眠dma.c进程 。 进程可被信号中断休眠,返回非0值表示休眠被信号中断 wait_event_interruptible(dma_wait_queue, dma_wait_queue_condition); if(memcmp(src,dest,DMA_SIZE) == 0) printk(" copy with DMA successfuly ! "); else printk("copy with DMA failed ! "); break; } } return 0; } //字符设备操作函数 static struct file_operations dma_fops = { .owner = THIS_MODULE, .ioctl = s3c_dma_iotcl, }; //中断处理函数 static int s3c_dma_irq(int irq, void *devid) { dma_wait_queue_condition = 1; //状态为真 唤醒dma.c进程 wake_up_interruptible(&dma_wait_queue); return IRQ_HANDLED; } static int dma_init(void) { //申请中断 request_irq(IRQ_DMA3, s3c_dma_irq,0, "s3c_dma", 1); //申请源地址空间 src = dma_alloc_writecombine(NULL,DMA_SIZE, &src_phy,GFP_KERNEL); //申请目的地址空间 dest= dma_alloc_writecombine(NULL,DMA_SIZE, &dest_phy,GFP_KERNEL); //dma_reg映射 s3c_dma_regs = ioremap(dma_addr3,sizeof(struct s3c_dma_reg)); //注册字符设备 major = register_chrdev(0, "s3c_dma",&dma_fops); //注册类 设备节点 dma_class = class_create(THIS_MODULE,"s3c_dma_class"); // /sys/class/s3c_dma_class class_device_create(dma_class,NULL,MKDEV(major,0),NULL, "s3c_dma"); // /dev/s3c_dma return 0; } static void dma_exit(void) { free_irq(IRQ_DMA3,1); dma_free_writecombine(NULL,DMA_SIZE, src,GFP_KERNEL); dma_free_writecombine(NULL,DMA_SIZE, dest,GFP_KERNEL); iounmap(s3c_dma_regs); unregister_chrdev(major, "s3c_dma"); class_destroy(dma_class); class_device_destroy( dma_class,MKDEV(major,0)); } module_init(dma_init); module_exit(dma_exit); MODULE_LICENSE("GPL");
以下是驱动测试文件：
#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/ioctl.h> #include <string.h> #define USE_DMA 1 #define NO_DMA 0 int main(int argc ,char **argv) { int fd=0; fd = open("/dev/s3c_dma", O_RDWR); if(fd<0) printf("can‘t open "); if(argc !=2) printf("please using like this : ./dma_test <dma|no_dma> "); if(argc ==2) { if(strcmp(argv[1],"dma")==0) while(1) ioctl(fd,USE_DMA); if(strcmp(argv[1],"no_dma")==0)while(1) ioctl(fd,NO_DMA); } return 0; }
以下是编译驱动的Makefile：
KERN_DIR = /work/systems/kernel/linux-2/linux-2.6.22.6 all: make -C $(KERN_DIR) M=`pwd` modules clean: make -C $(KERN_DIR) M=`pwd` modules clean rm -rf modules.order obj-m +=dma.o
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