NanoPi NEO小试牛刀（二）

你好！这里是风筝的博客，

欢迎和我一起交流。

前面写了NanoPi NEO的启动过程：NanoPi NEO小试牛刀（一）
但是我发现NanoPi NEO启动Linux内核时加载的东西太多了，Linux内核是没有经过剪裁的，我们可以试着剪裁优化下：

make menuconfig ARCH=arm CROSS_COMPILE=arm-linux-

Networking support —>Networking options—> Network packet filtering framework (Netfilter) 我不打算使用防火墙，要用到时再编译进去

Networking support—> < >CAN bus subsystem support 我不打算使用CAN总线

Networking support —> < > RF switch subsystem support 我没有RF 切换设备

Device Drivers —>< >Serial ATA and Parallel ATA drivers (libata) SATA或PATA接口的硬盘或光驱等设备

Device Drivers —>[ ] Multiple devices driver support (RAID and LVM) 暂时没有要使用Raid （磁盘阵列）和LVM （逻辑卷管理器，添加，删除逻辑分区）的需求

Device Drivers —> <> Sound card support 暂时没有无声卡

Device Drivers —> Graphics support –>< > DRM Support for Allwinner A10 Display Engine 没有视频播放

[ ] Virtualization 不需要

把这些都取消掉，然后选择支持nfs，这个好用：
File systems —> Network File Systems 支持nfs

最后保存退出，编译出来的zImage文件就小好多了

现在可以试着写一个简单的驱动试一下效果：
led.c：

/*Port A(PA): 22 input/output port ? Port C(PC): 19 input/output port ? Port D(PD): 18 input/output port ? Port E(PE) : 16 input/output port ? Port F(PF) : 7 input/output port ? Port G(PG) : 14 input/output port ? Port L(PL) : 12 input/output port PIO 0x01C20800 Pn_CFG0 n*0x24+0x00 Port n Configure Register 0 (n from 0 to 6)Pn_CFG1 n*0x24+0x04 Port n Configure Register 1 (n from 0 to 6)Pn_CFG2 n*0x24+0x08 Port n Configure Register 2 (n from 0 to 6)Pn_CFG3 n*0x24+0x0C Port n Configure Register 3 (n from 0 to 6)Pn_DAT n*0x24+0x10 Port n Data Register (n from 0 to 6)Pn_DRV0 n*0x24+0x14 Port n Multi-Driving Register 0 (n from 0 to 6)Pn_DRV1 n*0x24+0x18 Port n Multi-Driving Register 1 (n from 0 to 6)Pn_PUL0 n*0x24+0x1C Port n Pull Register 0 (n from 0 to 6)Pn_PUL1 n*0x24+0x20 Port n Pull Register 1 (n from 0 to 6)
*/#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/device.h>//#include <linux/of_address.h>
//#include <linux/of_platform.h>static volatile unsigned long *gpacon1;
static volatile unsigned long *gpadat;//a10/*CFG0_REG Default Value: 0x7777777* [30:28] Pn7_SELECT* [26:24] Pn6_SELECT* [22:20] Pn5_SELECT* [18:16] Pn4_SELECT* [14:12] Pn3_SELECT* [10: 8] Pn2_SELECT* [ 6: 4] Pn1_SELECT* [ 2: 0] Pn0_SELECT*000:Input                001:Output  111:disable*//*CFG1_REG Default Value: 0x7777777* [30:28] Pn15_SELECT* [26:24] Pn14_SELECT* [22:20] Pn13_SELECT* [18:16] Pn12_SELECT* [14:12] Pn11_SELECT* [10: 8] Pn10_SELECT* [ 6: 4] Pn9_SELECT* [ 2: 0] Pn8_SELECT*000:Input             001:Output *//*CFG2_REG Default Value: 0x7777777* [22:20] Pn21_SELECT* [18:16] Pn20_SELECT* [14:12] Pn19_SELECT* [10: 8] Pn18_SELECT* [ 6: 4] Pn17_SELECT* [ 2: 0] Pn16_SELECT*000:Input              001:Output
*//*Pn_DAT Default Value: 0x0* [21:0] if input :read pin state; if outport : pin state is same bit
*/static int led_open(struct inode *inode, struct file *file)
{printk("this is nanopi neo led \n");*gpacon1 |= (0x01<<(8));//PA10=Outputreturn 0;
}static ssize_t led_read(struct file * file, char __user *buf, size_t count, loff_t *off)
{printk("read nanopi neo led \n");//*gpadat &= ~(0x01<<(10));//PA10=0*gpadat |= (0x01<<(10));//PA10=1return 0;
}static ssize_t led_write(struct file *file, const char __user *buf,size_t count, loff_t *ppos)
{//*gpadatreturn 0;
}static struct file_operations led10_fops = {.owner  = THIS_MODULE,.open   = led_open,.read   = led_read, .write  = led_write,
};/* 1. 确定主设备号 */
static int major;
static struct cdev led10_cdev;
static struct class *cls;static int led_drv_init(void)
{int res;struct device * led_res;dev_t devid;/* 3. 告诉内核 */
#if 0major = register_chrdev(0, "hello", &hello_fops); /* (major,  0), (major, 1), ..., (major, 255)都对应hello_fops */
#else /*仅仅是注册设备号*/if (major) {devid = MKDEV(major, 0);register_chrdev_region(devid, 1, "led_blue");  /* (major,0) 对应 pwm_fops, (major, 1~255)都不对应pwm_fops */} else {alloc_chrdev_region(&devid, 0, 1, "led_blue"); /* (major,0) 对应 pwm_fops, (major, 1~255)都不对应pwm_fops */major = MAJOR(devid);                     }cdev_init(&led10_cdev, &led10_fops);res=cdev_add(&led10_cdev, devid, 1);if(res){printk("cdev_add failed\n");unregister_chrdev_region(MKDEV(major, 0), 1);return 0;}
#endifcls = class_create(THIS_MODULE, "led_blue");led_res = device_create(cls, (struct device *)NULL, MKDEV(major, 0), (void *)NULL, (const char *)"led_blue"); /* /dev/xxx */if (IS_ERR((const void *)res)) {printk("device_create failed\n");return 0;}gpacon1 = ioremap(0x01C20800+0*0x24+0x04 , 0x4*4);gpadat  = gpacon1+3;if (!gpacon1){printk("ioremap failed\n");return -EIO;}return 0;
}static void led_drv_exit(void)
{unregister_chrdev(major, "led_blue"); // 卸载device_destroy(cls,MKDEV(major, 0));class_destroy(cls);iounmap(gpacon1);
}module_init(led_drv_init);
module_exit(led_drv_exit);MODULE_LICENSE("GPL");

这就是一个简单的控制PA10管脚的程序，测试了下，可以使用。