DMA设备驱动(三)————基于Linux3.4.2的dma设备驱动的简单实现
2017-04-25 17:00
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#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/sched.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 <linux/poll.h> #include <linux/device.h> #include <linux/wait.h> #include <linux/interrupt.h> #include <mach/hardware.h> #include <mach/regs-gpio.h> #include <plat/gpio-cfg.h> #include <linux/dma-mapping.h> #include <linux/cdev.h> #define MEM_CPY_NO_DMA 0 #define MEM_CPY_DMA 1 #define BUF_SIZE (512*1024) #define DMA0_BASE_ADDR 0x4B000000 #define DMA1_BASE_ADDR 0x4B000040 #define DMA2_BASE_ADDR 0x4B000080 #define DMA3_BASE_ADDR 0x4B0000C0 struct s3c_dma_regs { 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 dmasktrig; }; static char *src; static u32 src_phys; static char *dst; static u32 dst_phys; static struct cdev dma_cdev; static dev_t dma_devno; static struct class *dma_class; static struct device *dma_device; static volatile struct s3c_dma_regs *dma_regs; static DECLARE_WAIT_QUEUE_HEAD(dma_waitq); /* 中断事件标志, 中断服务程序将它置1,ioctl将它清0 */ static volatile int ev_dma = 0; static int s3c_dma_ioctl( struct file *file, unsigned int cmd, unsigned long arg) { int i; memset(src, 0xAA, BUF_SIZE); memset(dst, 0x55, BUF_SIZE); switch (cmd) { case MEM_CPY_NO_DMA : { for (i = 0; i < BUF_SIZE; i++) dst[i] = src[i]; if (memcmp(src, dst, BUF_SIZE) == 0) { printk("MEM_CPY_NO_DMA OK\n"); } else { printk("MEM_CPY_DMA ERROR\n"); } break; } case MEM_CPY_DMA : { ev_dma = 0; /* 把源,目的,长度告诉DMA */ dma_regs->disrc = src_phys; /* 源的物理地址 */ dma_regs->disrcc = (0<<1) | (0<<0); /* 源位于AHB总线, 源地址递增 */ dma_regs->didst = dst_phys; /* 目的的物理地址 */ dma_regs->didstc = (0<<2) | (0<<1) | (0<<0); /* 目的位于AHB总线, 目的地址递增 */ dma_regs->dcon = (1<<30)|(1<<29)|(0<<28)|(1<<27)|(0<<23)|(0<<20)|(BUF_SIZE<<0); /* 使能中断,单个传输,软件触发, */ /* 启动DMA */ dma_regs->dmasktrig = (1<<1) | (1<<0); /* 如何知道DMA什么时候完成? */ /* 休眠 */ wait_event_interruptible(dma_waitq, ev_dma); if (memcmp(src, dst, BUF_SIZE) == 0) { printk("MEM_CPY_DMA OK\n"); } else { printk("MEM_CPY_DMA ERROR\n"); } break; } } return 0; } static struct file_operations dma_fops = { .owner = THIS_MODULE, .unlocked_ioctl = s3c_dma_ioctl, }; static irqreturn_t s3c_dma_irq(int irq, void *devid) { /* 唤醒 */ ev_dma = 1; wake_up_interruptible(&dma_waitq); /* 唤醒休眠的进程 4000 */ return IRQ_HANDLED; } static int s3c_dma_init(void) { int iError; if (request_irq(IRQ_DMA3, s3c_dma_irq, 0, "s3c_dma", 1)) { printk("can't request_irq for DMA\n"); return -EBUSY; } /* 分配SRC, DST对应的缓冲区 */ src = dma_alloc_writecombine(NULL, BUF_SIZE, &src_phys, GFP_KERNEL); if (NULL == src) { printk("can't alloc buffer for src\n"); free_irq(IRQ_DMA3, 1); return -ENOMEM; } dst = dma_alloc_writecombine(NULL, BUF_SIZE, &dst_phys, GFP_KERNEL); if (NULL == dst) { free_irq(IRQ_DMA3, 1); dma_free_writecombine(NULL, BUF_SIZE, src, src_phys); printk("can't alloc buffer for dst\n"); return -ENOMEM; } cdev_init(&dma_cdev, &dma_fops); iError = alloc_chrdev_region(&dma_devno, 0, 1, "s3c_dma"); if(iError < 0) { printk("alloc_chrdev_region failed!\n"); return -1; } iError = cdev_add(&dma_cdev, dma_devno, 1); if(iError < 0) { printk("cdev_add failed!\n"); return -1; } /* 为了自动创建设备节点 */ dma_class = class_create(THIS_MODULE, "s3c_dma"); dma_device = device_create(dma_class, NULL, dma_devno, NULL, "dma"); dma_regs = ioremap(DMA3_BASE_ADDR, sizeof(struct s3c_dma_regs)); return 0; } static void s3c_dma_exit(void) { iounmap(dma_regs); class_destroy(dma_class); device_destroy(dma_class, dma_devno); unregister_chrdev(dma_devno, "s3c_dma"); dma_free_writecombine(NULL, BUF_SIZE, src, src_phys); dma_free_writecombine(NULL, BUF_SIZE, dst, dst_phys); free_irq(IRQ_DMA3, 1); } module_init(s3c_dma_init); module_exit(s3c_dma_exit); MODULE_LICENSE("GPL");
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