platform设备驱动
kernel/arch/unicore/mach-sep0611/io.c:
map_desc 数组描述了开始有内核自动建立的虚拟空间到物理地址空间的映射(静态映射）
kernel/arch/unicore/mach-sep0611/devices.c:
描述了板级支持包，描述了各种资源的物理空间，以及各种platform_device实例的部分内容取值
kernel/arch/unicore/mach-sep0611/mach-tiger-test.c:
static struct platform_device *devices[] __initdata写明了支持platform架构的设备驱动
以globalfifo作为支持platform设备的驱动程序为例：
在kernel/arch/unicore/mach-sep0611/mach-tiger-test.c添加
static struct platform_device globalfifo_device =
{
.name = "globalfifo",
.id = -1,
};
在kernel/arch/unicore/mach-sep0611/mach-tiger-test.c的platform_device *数组devices中添加
&globalfifo_device,
驱动程序：
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/poll.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define GLOBALFIFO_SIZE 0x1000
#define MEM_CLEAR 0x1
#define GLOBALFIFO_MAJOR 234
#define DEVICE_NAME "globalfifo"
static int globalfifo_major = GLOBALFIFO_MAJOR;
struct globalfifo_dev *globalfifo_devp; //设备结构体指针
struct globalfifo_dev
{
struct cdev cdev;/*cdev结构体*/
unsigned int current_len; /*fifo有效数据长度*/
unsigned char mem[GLOBALFIFO_SIZE]; /*全局内存*/
struct semaphore sem; /*并发控制用的信号量*/
wait_queue_head_t r_wait; /*阻塞读用的等待队列头*/
wait_queue_head_t w_wait; /*阻塞写用的等待队列头*/
};
/*globalfifo轮询操作*/
static unsigned int globalfifo_poll(struct file *filp, poll_table *wait)
{
unsigned int mask = 0;
struct globalfifo_dev *dev = filp->private_data;/*获得设备结构体指针*/
down(&dev->sem);
poll_wait(filp, &dev->r_wait, wait);
poll_wait(filp, &dev->w_wait, wait);
/*fifo非空*/
if(dev->current_len != 0)
{
mask |= POLLIN | POLLRDNORM; /*标示数据可获得*/
}
/*fifo非满*/
if(dev->current_len != GLOBALFIFO_SIZE)
{
mask |= POLLOUT | POLLWRNORM; /*标示数据可写入*/
}
up(&dev->sem);
return mask;
}
/*globalfifo读函数*/
static ssize_t globalfifo_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
int ret;
struct globalfifo_dev *dev = filp->private_data;/*获得设备结构体指针*/
DECLARE_WAITQUEUE(wait, current);/*定义等待队列*/
down(&dev->sem);/*获得信号量*/
add_wait_queue(&dev->r_wait, &wait);/*进入读等待队列*/
/*等待FIFO非空*/
while(dev->current_len == 0)
{
if(filp->f_flags & O_NONBLOCK)
{
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE);/*改变进程状态为睡眠*/
up(&dev->sem);
schedule();/*调度其它进程执行*/
if(signal_pending(current))
{
/*如果是因为信号被唤醒*/
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);
}
/*拷贝到用户空间*/
if(count > dev->current_len)
{
count = dev->current_len;
}
if(copy_to_user(buf, (void*)(dev->mem), count))
{
ret = -EFAULT;
goto out;
}
else
{
memcpy(dev->mem, dev->mem + count, dev->current_len - count);/*fifo数据前移*/
dev->current_len -= count; /*有效数据长度减小*/
printk(KERN_INFO "read %d bytes, current_len:%d\n", count, dev->current_len);
wake_up_interruptible(&dev->w_wait);/*唤醒写等待队列*/
ret = count;
}
out:
up(&dev->sem);/*释放信号*/
out2:
remove_wait_queue(&dev->r_wait, &wait);/*移除等待队列*/
set_current_state(TASK_RUNNING);
return ret;
}
/*globalfifo 写操作*/
static ssize_t globalfifo_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
struct globalfifo_dev *dev = filp->private_data;/*获得设备结构体指针*/
int ret;
DECLARE_WAITQUEUE(wait, current); /*定义等待队列*/
down(&dev->sem); /*获取信号量*/
add_wait_queue(&dev->w_wait, &wait); /*进入写等待队列*/
/*等待FIFO非满*/
while(dev->current_len == GLOBALFIFO_SIZE)
{
if(filp->f_flags & O_NONBLOCK)
{
/*如果是非阻塞访问*/
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE); /*改变进程状态为睡眠*/
up(&dev->sem);
schedule();/*调度其它进程执行*/
if(signal_pending(current))
{
/*如果是因为信号唤醒*/
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);/*获得信号量*/
}
/*从用户空间拷贝到内核空间*/
if(count > GLOBALFIFO_SIZE - dev->current_len)
count = GLOBALFIFO_SIZE - dev->current_len;
if(copy_from_user(dev->mem + dev->current_len, buf, count))
{
ret = -EFAULT;
goto out;
}
else
{
dev ->current_len += count;
printk(KERN_INFO "written %d bytes, current_len: %d\n", count, dev->current_len);
wake_up_interruptible(&dev->r_wait);/*唤醒读等待队列*/
ret = count;
}
out:
up(&dev->sem);/*释放信号量*/
out2:
remove_wait_queue(&dev->w_wait, &wait);
set_current_state(TASK_RUNNING);
return ret;
}
static loff_t globalfifo_llseek(struct file *filp, loff_t offset, int orig)
{
loff_t ret;
switch(orig)
{
case 0:
if(offset < 0)
{
ret = -EINVAL;
break;
}
if(offset > GLOBALFIFO_SIZE)
{
ret = -EINVAL;
break;
}
filp->f_pos = (unsigned int)offset;
ret = filp->f_pos;
break;
case 1:
if((filp->f_pos + offset) > GLOBALFIFO_SIZE)
{
ret = -EINVAL;
break;
}
if((filp->f_pos + offset) < 0)
{
ret = -EINVAL;
break;
}
filp->f_pos +=offset;
ret = filp->f_pos;
break;
default:
ret = -EINVAL;
}
return ret;
}
static int globalfifo_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
struct globalfifo_dev *dev = filp->private_data;
switch(cmd)
{
case MEM_CLEAR:
if(down_interruptible(&dev->sem))
{
return -ERESTARTSYS;
}
memset(dev->mem, 0, GLOBALFIFO_SIZE);
up(&dev->sem);//释放信号量
printk(KERN_INFO "globalfifo is set to zero\n");
break;
default:
return -EINVAL;
}
return 0;
}
int globalfifo_release(struct inode *inode, struct file *filp)
{
return 0;
}
int globalfifo_open(struct inode *inode, struct file *filp)
{
filp->private_data = globalfifo_devp;//将设备结构体指针赋值给文件私有数据指针
return 0;
}
struct file_operations globalfifo_fops =
{
.owner = THIS_MODULE,
.llseek = globalfifo_llseek,
.read = globalfifo_read,
.write = globalfifo_write,
.release = globalfifo_release,
.open = globalfifo_open,
.ioctl = globalfifo_ioctl,
.poll = globalfifo_poll,
};
static void globalfifo_setup_cdev(struct globalfifo_dev *dev, int index)
{
int err;
int devno = MKDEV(globalfifo_major, index);
cdev_init(&dev->cdev, &globalfifo_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &globalfifo_fops;//?????
err = cdev_add(&dev->cdev, devno, 1);
if(err)
printk(KERN_NOTICE "Error %d adding LED %d", err, index);
}
static int __devinit globalfifo_probe(struct platform_device *pdev)
{
printk(KERN_NOTICE "%s\n", __func__);
int ret;
dev_t devno = MKDEV(globalfifo_major, 0);
/*申请设备号*/
if(globalfifo_major)
{
ret = register_chrdev_region(devno, 1, "globalfifo");
}
else
{
ret = alloc_chrdev_region(&devno, 0, 1, "globalfifo");
globalfifo_major = MAJOR(devno);
}
if(ret < 0)
{
return ret;
}
/*动态申请设备结构提内存*/
globalfifo_devp = kmalloc(sizeof(struct globalfifo_dev), GFP_KERNEL);
if(!globalfifo_devp)
{
/*申请失败*/
ret = -ENOMEM;
goto fail_malloc;
}
memset(globalfifo_devp, 0, sizeof(struct globalfifo_dev));
globalfifo_setup_cdev(globalfifo_devp, 0);
sema_init(&globalfifo_devp->sem, 1);/*初始化信号量*/
init_waitqueue_head(&globalfifo_devp->r_wait);//初始化读等待队列
init_waitqueue_head(&globalfifo_devp->w_wait);//初始化写等待队列头
return 0;
fail_malloc:
unregister_chrdev_region(devno, 1);
return ret;
}
static int __devexit globalfifo_remove(struct platform_device *pdev)
{
cdev_del(&globalfifo_devp->cdev);//注销cdev
kfree(globalfifo_devp);//释放设备结构体内存
unregister_chrdev_region(MKDEV(globalfifo_major, 0), 1);//释放设备号
return 0;
}
static struct platform_driver globalfifo_device_driver =
{
.probe = globalfifo_probe,
.remove = __devexit_p(globalfifo_remove),
.driver =
{
.name = "globalfifo",
.owner = THIS_MODULE,
}
};
static int __init globalfifo_init(void)
{
printk(KERN_NOTICE "%s\n", __func__);
return platform_driver_register(&globalfifo_device_driver);
}
void __exit globalfifo_exit(void)
{
platform_driver_unregister(&globalfifo_device_driver);
}
module_param(globalfifo_major, int, S_IRUGO);
module_init(globalfifo_init);
module_exit(globalfifo_exit);
MODULE_LICENSE("Dual BSD/GPL");
