玩转移远SC60 Android开发板------（4）USB和otg切换

淩亂°似流年 2023-01-11 03:38 359阅读 0赞

在SC60上打算实现usb device和otg的软切换，即通过软件设置实现usb device和otg的切换。  
原理图上可以设计一个GPIO来控制USB ID和数据线的切换。VBUS的供电方面，otg使用外供电，可以不用考虑；作device时vbus用来检测插入即可。  
参考原理图如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcm5lcnN0b25lMQ_size_16_color_FFFFFF_t_70]  
图中使用GPIO\_96作为控制切换的管脚，它输出0时，USB\_ID脚为高，s脚为高，usb切换开关选择的是HSD1：USB\_DP\_EXT和USB\_DM\_EXT，此时模块作为device；  
GPIO\_96输出1时，USB\_ID脚为低，usb切换开关选择的是HSD2：USB\_DP\_COM和USB\_DM\_COM，此时模块作为host，外部连接otg设备。

**参考驱动：**

#include <linux/device.h>
    #include <asm/io.h>
    #include <linux/init.h>
    #include <linux/sched.h>
    #include <linux/mm.h>
    #include <linux/uaccess.h>
    #include <linux/slab.h>
    #include <linux/cdev.h>
    #include <linux/types.h>
    #include <linux/fs.h> 
    #include <linux/module.h>
    #include <linux/semaphore.h>
    #include <linux/of_device.h>
    #include <linux/of_platform.h>
    #include <linux/sched.h>
    #include <linux/kthread.h>
    #include <linux/delay.h>
    #include <linux/gpio.h>
    
    #define SC60_GPIO_SET_MAJOR    198
    #define SC60_DO1            0x1
    #define SC60_DO2            0x2
    
    
    u32 gpio_num[]={
      96,
    };
    
    
    struct SC60_gpio_dev{
    	struct cdev cdev;
    };
    
    struct SC60_gpio_dev *SC60_gpio_devp;
    
    static int SC60_gpio_major = SC60_GPIO_SET_MAJOR;
    
    
    int SC60_gpio_open(struct inode *inode, struct file *filp)
    {
    	//printk(KERN_ERR "###sc60### SC60_gpio open in\n");
    	filp->private_data = SC60_gpio_devp;
    
    	return 0;
    }
    
    int SC60_gpio_release(struct inode *inode, struct file *filp)
    {
    	//printk(KERN_ERR "###sc60### SC60_gpio release in\n");
    	return 0;
    }
    
    static ssize_t SC60_gpio_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
    {
    	__attribute__((__unused__)) struct SC60_gpio_dev *dev = filp->private_data;
    	//copy_to_user
    	//printk(KERN_ERR "###sc60### SC60_gpio read in\n");
    	
    	return 0;
    }
    
    static ssize_t SC60_gpio_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
    {
    	__attribute__((__unused__)) struct SC60_gpio_dev *dev = filp->private_data;
    	//copy_from_user
    	//printk(KERN_ERR "###sc60### SC60_gpio write in\n");
    
    	return -1;
    }
    
    static loff_t SC60_gpio_llseek(struct file *filp, loff_t offset, int orig)
    {
    	//printk(KERN_ERR "###sc60### SC60_gpio llseek in\n");
    	//filp->f_pos
    	switch(orig){
    	case 0:
    		break;
    	case 1:
    		break;
    	default:
    		break;
    	}
    
    	return 0;
    }
    
    static long SC60_gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
    {
    	__attribute__((__unused__)) struct SC60_gpio_dev *dev = filp->private_data;
    	//printk(KERN_ERR "###sc60### SC60_gpio ioctl in\n");
    	
    	switch(cmd){
    	case SC60_DO1:
    		break;
    	case SC60_DO2:
    	default:
    		break;
    	}
    
    	return 0;
    }
    
    static const struct file_operations SC60_gpio_fops = {
    	.owner = THIS_MODULE,
    	.llseek = SC60_gpio_llseek,
    	.read = SC60_gpio_read,
    	.write = SC60_gpio_write,
    	.unlocked_ioctl = SC60_gpio_ioctl,
    	.open = SC60_gpio_open,
    	.release = SC60_gpio_release,
    };
    
    struct class *SC60_gpio_class;
    
    static void SC60_gpio_setup_cdev(struct SC60_gpio_dev *dev, int index)
    {
    	int err, devno;
    	devno = MKDEV(SC60_gpio_major, index);
    	printk(KERN_ERR "###sc60### SC60_gpio SC60_gpio_setup_cdev\n");
    
    	cdev_init(&dev->cdev, &SC60_gpio_fops);
    	dev->cdev.owner = THIS_MODULE;
    	err = cdev_add(&dev->cdev, devno, 1);
    	if(err)
    	{
    		printk(KERN_ERR "###sc60### %d add SC60_gpio %d\n", err, index);
    	}
    
    	SC60_gpio_class = class_create(THIS_MODULE, "sc60_otg_set");
    	//stone comment
    	//这里的名字是/dev/下面的名字
    	// create device in /dev/sc60_otg_set
    	//实际在/sys/class/sc60_otg_set
    	// but the real device is /sys/bus/platform/devices/SC60_otg_control
    	device_create(SC60_gpio_class, NULL, devno, NULL, "sc60_otg_set");
    }
    
    static bool gpio_flag = 0;
    
    static ssize_t SC60_gpio_get(struct device *dev, struct device_attribute *attr, char *buf)
    {
    	int ret = 0;
    
    	if(gpio_flag)
    		//print chars to buf
    		//ret = snprintf(buf, PAGE_SIZE, "%d\n", SC60_adc1_to_vol());
    		ret = snprintf(buf, PAGE_SIZE, "--otg set--\n");
    	else
    		ret = snprintf(buf, PAGE_SIZE, "--host set--\n");
    
    	return ret;
    }
    
    static ssize_t SC60_gpio_set(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
    {
    	int stat;
    
    	//char to int
    	stat = buf[0] - '0';
    
    	printk(KERN_ERR "set gpio status :%d \n", stat);
    	
    	gpio_free(gpio_num[0]);
    	gpio_request(gpio_num[0], NULL);
    	if(stat == 0)
    	{
    		gpio_direction_output(gpio_num[0], 0);
    		gpio_flag = stat;
    	}
    	if(stat == 1)
    	{
    		gpio_direction_output(gpio_num[0], 1);
    		gpio_flag = stat;
    	}
    		
    	return count;
    }
    static DEVICE_ATTR(SC60_gpio, 0664, SC60_gpio_get, SC60_gpio_set);
    
    
    static int __init SC60_gpio_probe(struct platform_device *pdev)
    {
    	int result;
    	
    	dev_t devno = MKDEV(SC60_gpio_major, 0);
    	printk(KERN_ERR "###sc60### SC60_gpio_probe in\n");
    
    	if(SC60_gpio_major)
    	{
    		//这里是分配设备号
    		//cat proc/devices 看到198 SC60_gpio_control
    		result = register_chrdev_region(devno, 1, "SC60_gpio_control");
    	}
    	else
    	{
    		result = alloc_chrdev_region(&devno, 0, 1, "SC60_gpio_control");
    		SC60_gpio_major = MAJOR(devno);
    	}
    	if(result < 0)
    	{
    		return result;
    	}
    
    	SC60_gpio_devp = kmalloc(sizeof(struct SC60_gpio_dev), GFP_KERNEL);
    	
    	if(!SC60_gpio_devp){
    		result = -ENOMEM;
    		goto fail_malloc;
    	}
    	memset(SC60_gpio_devp, 0, sizeof(struct SC60_gpio_dev));
    
    	SC60_gpio_setup_cdev(SC60_gpio_devp, 0);
    
    	
    	//这里创建的节点是在/sys/bus/platform/devices/SC60_otg_control下
    	//SC60_otg_control这个名字是由SC60_gpio_device和SC60_gpio_device_driver的名字决定的
    	device_create_file(&pdev->dev, &dev_attr_sc60_gpio);
    
    	printk(KERN_ERR "###sc60### SC60_gpio_probe out\n");
    
    	return 0;
    
    fail_malloc:
    	unregister_chrdev_region(devno, 1);
    	
    	return result;
    }
    
    static int __exit SC60_gpio_remove(struct platform_device *pdev)
    {
    	cdev_del(&SC60_gpio_devp->cdev);
    	kfree(SC60_gpio_devp);
    
    	device_destroy(SC60_gpio_class, MKDEV(SC60_gpio_major, 0));
    	class_destroy(SC60_gpio_class);
    
    	unregister_chrdev_region(MKDEV(SC60_gpio_major, 0), 1);
    	return 0;
    }
    
    static struct platform_driver SC60_gpio_device_driver = {
            .probe   = SC60_gpio_probe,
            .remove  = SC60_gpio_remove,
    
            .driver  = {
                    .name = "SC60_otg_control",
                    .owner = THIS_MODULE,
            },
    };
    
    static struct platform_device SC60_gpio_device = {
            .name    = "SC60_otg_control",
            .id      = -1,
    };
    
    static int __init SC60_gpio_init(void)
    {
    	platform_device_register(&SC60_gpio_device);
    	return platform_driver_register(&SC60_gpio_device_driver);
    }
    
    static void __exit SC60_codec_exit(void)
    {
    	platform_driver_unregister(&SC60_gpio_device_driver);
    	platform_device_unregister(&SC60_gpio_device);
    }
    
    module_init(SC60_gpio_init);
    module_exit(SC60_codec_exit);
    
    MODULE_LICENSE("GPL");
    MODULE_AUTHOR("stone");
    MODULE_DESCRIPTION("stone for SC60 gpio-set CTRL");

这样就可以使用节点控制usb状态了。  
读取otg状态：  
cat /sys/bus/platform/devices/sc60\_otg\_control/sc60\_gpio  
设置otg状态：  
echo 1 > /sys/bus/platform/devices/sc60\_otg\_control/sc60\_gpio  
设置USB状态：  
echo 0 > /sys/bus/platform/devices/sc60\_otg\_control/sc60\_gpio

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