MB85RC铁电 FRAM驱动（全志平台linux）

测试几天发现一个bug，就是无法一次读取32个字节的数据，1-31,33,128,512都试过了，唯独无法读取32个字节，驱动未报错，但是读取的都是0，找不到原因，估计应该是全志iic驱动的问题，暂时没有折腾，尽量避开32字节读取吧，32字节写入是没问题的。

使用的字符驱动，可以读写任意字节（32字节读取除外），可以使用lseek设置读写地址，首先设置内核设备数，在对应的iic节点下添加fram支持。

fram: fram@50 {compatible = "general,iic_fram";reg = <0x50>;};

驱动代码如下

// SPDX-License-Identifier: GPL-2.0+
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/gpio/consumer.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/regulator/consumer.h>
#include <linux/uaccess.h>
#include <linux/device.h>			//自动创建/dev设备节点需要
#include <linux/kdev_t.h>           //设备号用到的头文件和宏函数
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>typedef unsigned int  u32;
typedef unsigned short u16;
typedef unsigned char  u8;typedef volatile unsigned int  vu32;
typedef volatile unsigned short vu16;
typedef volatile unsigned char  vu8;typedef unsigned int  const uc32;  /* Read Only */
typedef unsigned short const uc16;  /* Read Only */
typedef unsigned char  const uc8;   /* Read Only */#define DEVICE_NAME			"iic_fram" 	// 设备名字
#define DTS_COMPATIBLE		"general,iic_fram"	//设备树中对应的COMPATIBLE信息名称//注意：fram使用的是 MB85RC16PNF-G-JNERE1 进行测试2KB容量，FRAM的通讯有点不一样，芯片地址为4bit，然后3bit寄存器高地址，1bit读写标识，最终依旧使用的是8bit寄存器模式，但是地址范围0-7FF//设备驱动私有结构体数据定义
struct fram_type {int fram_init_finished;struct i2c_client* fram_client;struct mutex mutex_lock;//定义互斥锁struct class* device_class;		//注册后的设备节点classstruct device* device;	//注册的设备dev_t devno;			//设备号struct cdev cd;int size;				//容量信息
};
static struct fram_type* sg_fram = NULL;	//再iic设备注册后进行初始化，非NULL意味着硬件初始化正常，在probe中进行初始化//注册驱动时传入参数，参数为farm容量信息，默认为2KB，单位字节
static int SIZE = -1;				//通过注册驱动的时候传入参数，如 insmode iic_fram SIZE=4096 实现容量设置
module_param(SIZE, int, S_IRUSR);	//S_IRUSR在include/linux/stat.h/*************************************************************************************************************************
*函数        	:	int fram_read_data(struct i2c_client* client, u16 addr, u16 ByteCount, u8* pData, bool isKernel)
*功能        	:	iic驱动读取寄存器数据
*参数        	:	client:句柄；addr：寄存器地址；ByteCount：要读取的数据数量；pData:数据缓冲区;isKernel:是否是内核读取，如果是内核读取将不需要进行内核数据与用户空间数据转换
*返回        	:	<0 错误，其它：读取的字节数
*依赖			: 	底层宏定义
*作者				:	cp1300@139.com
*时间     		:	2024-03-04
*最后修改时间		:	2024-03-04
*说明        	:	
*************************************************************************************************************************/
int fram_read_data(struct i2c_client* client, u16 addr, u16 ByteCount, u8 __user* pData, bool isKernel)
{int ret;u8 addr_buff[1];u8* pkbuff;struct i2c_msg msgs[] = {//写命令{.addr = client->addr | ((addr >> 8) & 0x07),.flags = 0,.len = 1,				//数据长度为1字节的地址.buf = addr_buff,		//寄存器地址},//读取数据{.addr = client->addr | ((addr >> 8) & 0x07),.flags = I2C_M_RD,.len = ByteCount,		//数据长度为n字节的数据.buf = NULL,			//buf-等会设置}};//dev_info(&client->dev, "i2c_smbus_read_16bit_i2c_block_data addr=%d ByteCount=%d client->addr=%d\r\n", addr, ByteCount, client->addr);//申请内核内存，准备读取数据pkbuff = (u8*)kmalloc(ByteCount, GFP_KERNEL | GFP_DMA | __GFP_ZERO);	//申请内存-iic会用到DMA，内存要连续if (pkbuff == NULL){printk("fram read out of memory! kmalloc(%dB)\r\n", ByteCount);return -1;}msgs[1].buf = pkbuff;	//读取的数据存放到缓冲区//准备寄存器地址数据addr_buff[0] = addr & 0xFF;					//地址低位ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));	//写入命令，读取数据if (ret <= 0){dev_err(&client->dev, "i2c_transfer read addr=%d ByteCount=%d failed!\r\n", addr, ByteCount);ret = -1;}else{if (isKernel == true) //当前处于内核空间{memcpy(pData, pkbuff, ByteCount);ret = ByteCount;	//返回数据长度}else{ret = copy_to_user(pData, pkbuff, ByteCount);  //读取成功，将数据拷贝到用户空间if (ret != 0){printk("fram copy_to_user error(%dB)\r\n", ret);ret = -1;}else{ret = ByteCount;	//返回数据长度}}}kfree(pkbuff);	//释放申请的内存return ret;
}/*************************************************************************************************************************
*函数        	:	int fram_write_data(struct i2c_client* client, u16 addr, u16 ByteCount, u8* pData)
*功能        	:	iic驱动写入寄存器数据
*参数        	:	client:句柄；addr：寄存器地址；ByteCount：要读取的数据数量；pData:数据缓冲区
*返回        	:	<0 错误，其它：读取的字节数
*依赖			: 	底层宏定义
*作者				:	cp1300@139.com
*时间     		:	2024-03-04
*最后修改时间		:	2024-03-04
*说明        	:	
*************************************************************************************************************************/
int fram_write_data(struct i2c_client* client, u16 addr, u16 ByteCount, const u8 __user* pData)
{int ret;u8* buf;struct i2c_msg msgs[] = {//写数据命令{.addr = client->addr | ((addr >> 8) & 0x07),.flags = 0,.len = ByteCount + 1,	//数据长度为2字节的地址，n字节的数据//.buf = &reg,			//buf等会赋值，需要申请内存}};//dev_info(&client->dev, "i2c_smbus_write_16bit_i2c_block_data write addr=%d ByteCount=%d\r\n", addr, ByteCount);buf = (u8*)kmalloc(ByteCount + 1, GFP_KERNEL | GFP_DMA | __GFP_ZERO);	//申请内存-iic会用到DMA，内存要连续if (buf == NULL){dev_err(&client->dev, "i2c_smbus_write_16bit_i2c_block_data out of memory! kmalloc(%dB)\r\n", ByteCount + 1);return -1;}msgs[0].buf = buf;						//记录申请的内存//准备数据buf[0] = addr & 0xFF;					//地址低位ret = copy_from_user(&buf[1], pData, ByteCount);	//用户空间数据拷贝到内核空间if (ret != 0) {printk("fram copy_from_user error(%dB)\r\n", ret);ret = -EFAULT;}else{ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));	//写入数据if (ret == ARRAY_SIZE(msgs)){ret = ByteCount;	//返回写入的数据长度}else{dev_err(&client->dev, "i2c_transfer write addr=%d ByteCount=%d failed!\r\n", addr, ByteCount);ret = -1;}}kfree(buf);	//释放申请的内存return ret;
}/*************************************************************************************************************************
*函数        	:	int fram_Init(struct i2c_client* client)
*功能        	:	fram初始化
*参数        	:	client:iic句柄
*返回        	:	0:初始化成功；其它:初始化失败
*依赖			: 	底层宏定义
*作者				:	cp1300@139.com
*时间     		:	2024-03-03
*最后修改时间		:	2024-03-03
*说明        	:
*************************************************************************************************************************/
int fram_Init(struct i2c_client* client)
{u8 i;struct fram_type* fram = i2c_get_clientdata(client);	//获取私有数据int ret;u8 temp;if (fram == NULL){dev_err(&client->dev, "i2c_get_clientdata(client) null\r\n");return -1;}//读取地址0，只要能读取到就认为初始化成功for (i = 0; i < 3; i++){ret = fram_read_data(client, 0, 1, &temp, true);if (ret < 0){dev_err(&client->dev, "Failed to read 0x00\r\n");msleep(5);}else{dev_info(&client->dev, "addr 0x00:0x%X\r\n", temp);break;}}if (ret < 0) return -1;return 0;
}//===========================================================================================
//标准文件接口相关
/** @description		: 打开设备* @param - inode 	: 传递给驱动的inode* @param - filp 	: 设备文件，file结构体有个叫做private_data的成员变量* 					  一般在open的时候将private_data指向设备结构体。* @return 			: 0 成功;其他 失败*/
static int device_open(struct inode* inode, struct file* filp)
{if (sg_fram == NULL){printk("fram not initialized\r\n");return -1;}//dev_info(&sg_fram->fram_client->dev, "device_open\n");return 0;
}/** @description		: 从设备读取数据* @param - filp 	: 要打开的设备文件(文件描述符)* @param - buf 	: 返回给用户空间的数据缓冲区* @param - cnt 	: 要读取的数据长度* @param - offt 	: 相对于文件首地址的偏移* @return 			: 读取的字节数，如果为负值，表示读取失败*/
static ssize_t device_read(struct file* filp, char __user* buf, size_t cnt, loff_t* offt)
{u32 offset = (u32)*offt;int ret;if (sg_fram == NULL){printk("fram not initialized\r\n");return -1;}if (buf == NULL){printk("buf is NULL!\r\n");return -EFAULT;}if (cnt == 0 || cnt > sg_fram->size || (cnt + offset) > sg_fram->size){printk("fram Read out of range cnt=%d offt=%d(max size:%dB)\r\n", cnt, offset, sg_fram->size);return 0;}//读取数据mutex_lock(&sg_fram->mutex_lock);	//阻塞式上互斥锁，抢不到就一直阻塞ret = fram_read_data(sg_fram->fram_client, (u16)offset, (u16)cnt, buf, false);mutex_unlock(&sg_fram->mutex_lock);	//解锁return ret;
}/** @description		: 向设备写数据* @param - filp 	: 设备文件，表示打开的文件描述符* @param - buf 	: 要写给设备写入的数据* @param - cnt 	: 要写入的数据长度* @param - offt 	: 相对于文件首地址的偏移* @return 			: 写入的字节数，如果为负值，表示写入失败*/
static ssize_t device_write(struct file* filp, const char __user* buf, size_t cnt, loff_t* offt)
{u32 offset = (u32)*offt;int ret;if (sg_fram == NULL){printk("fram not initialized\r\n");return -1;}if (buf == NULL){printk("buf is NULL!\r\n");return -EFAULT;}if (cnt == 0 || cnt > sg_fram->size || (cnt + offset) > sg_fram->size){printk("fram write out of range cnt=%d offt=%d(max size:%dB)\r\n", cnt, offset, sg_fram->size);return 0;}mutex_lock(&sg_fram->mutex_lock);	//阻塞式上互斥锁，抢不到就一直阻塞ret = fram_write_data(sg_fram->fram_client, (u16)offset, (u16)cnt, buf);mutex_unlock(&sg_fram->mutex_lock);	//解锁return ret;
}/** @description		: 设置文件读写偏移* @param - filp 	: 设备文件，表示打开的文件描述符* @param - off 	: 读写偏移* @param - whence 	: 光标参考位置* @return 			: 当前文件的纸质位置，如果为负值，表示写入失败*/
static loff_t device_llseek(struct file* filp, loff_t off, int whence)
{//struct scull_dev* dev = filp->private_data;loff_t newpos;//printk("device_llseek off=%u whence=%d\r\n", (u32)off, whence);switch (whence){case 0: //SEEK_SET 从开始的偏移{newpos = off;if (newpos >= sg_fram->size) newpos = sg_fram->size - 1;	//防止超出范围}break;case 1:	//SEEK_CUR 在当前位置加上偏移{newpos = filp->f_pos + off;if (newpos >= sg_fram->size) newpos = sg_fram->size - 1;	//防止超出范围}break;case 2: //SEEK_END 偏移位置文件结尾 之外{newpos = sg_fram->size - 1;	//不允许超出文件}break;default: return -EINVAL;}if (newpos < 0) return -EINVAL;filp->f_pos = newpos;return newpos;
}/** @description		: 关闭/释放设备* @param - filp 	: 要关闭的设备文件(文件描述符)* @return 			: 0 成功;其他 失败*/
static int device_release(struct inode* inode, struct file* filp)
{//printk("fram_release\r\n");return 0;
}//申请i2c资源，顺便进行初始化
static int device_probe(struct i2c_client *client,const struct i2c_device_id *id)
{int ret;struct fram_type* fram;dev_info(&client->dev, "fram_probe\n");//判断iic适配器是否正常if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)){return -ENODEV;}//申请内核内存资源fram = devm_kzalloc(&client->dev, sizeof(struct fram_type), GFP_KERNEL);if (!fram){return -ENOMEM;}fram->fram_init_finished = 0;			//初始化未完成fram->fram_client = client;			//记录i2c接口指针fram->device_class = NULL;						//设备节点无效fram->device = NULL;						//设备节点无效//需要提前设置，否则在 fram_Init 中需要调用 i2c_get_clientdata () 将返回空i2c_set_clientdata(client, fram);		// 将fram作为i2c次设备的私有数据区中的设备驱动私有数据if (SIZE > 0){dev_info(&client->dev, "SIZE=%dB\n", SIZE &0xFFFF);}else{SIZE = 2048;	//默认为2KB}if (SIZE < 128) SIZE = 128;if (SIZE > 0x7FF) SIZE = 0x7FF;	//最大大小限制为0x7FFfram->size = SIZE;		//初始化FRAM大小dev_info(&client->dev, "FRAM SIZE:%dB\n", fram->size);//开始芯片硬件探测与初始化ret = fram_Init(client);	//初始化并设置初值，也可以通过注册驱动的时候传入参数实现初始化if (ret < 0){dev_err(&client->dev, "invalid init fram\n");return -1;}mutex_init(&fram->mutex_lock);//初始化互斥锁sg_fram = fram;						//记录全局设备数据，设备硬件初始化完成了fram->fram_init_finished = 1;			//初始化完成dev_info(&client->dev, "fram probe succeeded\n");return 0;
}//移除iic驱动
static int device_remove(struct i2c_client* client)
{struct fram_type* fram = i2c_get_clientdata(client);	//获取私有数据dev_info(&client->dev, "fram_remove\n");//释放互斥锁信号if (fram != NULL && fram->fram_init_finished){mutex_destroy(&fram->mutex_lock);}return 0;
}//===========================================================================================
//iic接口相关
static const struct of_device_id fram_match_table[] = {{.compatible = DTS_COMPATIBLE,},{},
};
MODULE_DEVICE_TABLE(of, fram_match_table);static const struct i2c_device_id fram_id[] = {{ DTS_COMPATIBLE, 0 },{},
};
MODULE_DEVICE_TABLE(i2c, fram_id);static struct i2c_driver fram_driver = {.driver = {.name		= DEVICE_NAME,.owner		= THIS_MODULE,.of_match_table = fram_match_table,},.probe    = device_probe,	//注册IIC.remove = device_remove,.id_table	= fram_id,};//module_i2c_driver(fram_driver);	//需要使用 i2c_add_driver 在 init中进行注册iic适配器，不能直接使用宏//设备驱动操作相关接口结构体
static struct file_operations sg_device_opera_fops = {.owner = THIS_MODULE,.open = device_open,		//打开驱动文件接口.read = device_read,		//读取接口.write = device_write,		//写文件接口.release = device_release,	//释放文件接口.llseek = device_llseek,	//设置文件偏移//.ioctl = device_ioctl,		//参数设置接口
};//驱动接口-驱动入口函数-初始化与申请资源
static int __init device_init(void)
{int retvalue;//printk("device_module_init\n");retvalue = i2c_add_driver(&fram_driver);	//添加iic驱动if (retvalue) {printk("%s i2c_add_driver failed! %d\n", __func__, retvalue);return -ENODEV;}if (sg_fram == NULL) //设备硬件初始化失败{printk("initialization failed!\r\n");return -EIO;}//注册字符设备驱动retvalue = alloc_chrdev_region(&sg_fram->devno, 0, 1, DEVICE_NAME);	//自动申请设备号，从0开始，申请1个if (retvalue < 0) {pr_err("alloc_chrdev_region failed!(%d)", retvalue);i2c_del_driver(&fram_driver);				//移除iic设备return retvalue;}printk("MAJOR is %d\n", MAJOR(sg_fram->devno));printk("MINOR is %d\n", MINOR(sg_fram->devno));cdev_init(&sg_fram->cd, &sg_device_opera_fops);			//字符驱动结构体初始化retvalue = cdev_add(&sg_fram->cd, sg_fram->devno, 1);	//注册字符设备驱动，数量1if (retvalue < 0) {pr_err("cdev_add failed!(%d)", retvalue);i2c_del_driver(&fram_driver);				//移除iic设备unregister_chrdev_region(sg_fram->devno, 1);	//注销一个范围的设备号return retvalue;}//自动在/dev目录下创建设备节点sg_fram->device_class = class_create(THIS_MODULE, DEVICE_NAME);	创建类if (NULL == sg_fram->device_class){printk(KERN_INFO "create calss failed\n");cdev_del(&sg_fram->cd);unregister_chrdev_region(sg_fram->devno, 1);	//注销一个范围的设备号i2c_del_driver(&fram_driver);				//移除iic设备return -1;}else{sg_fram->device = device_create(sg_fram->device_class, NULL, sg_fram->devno, NULL, DEVICE_NAME);	//创建设备if (NULL == sg_fram->device){printk(KERN_INFO "create device failed\n");cdev_del(&sg_fram->cd);unregister_chrdev_region(sg_fram->devno, 1);class_destroy(sg_fram->device_class);i2c_del_driver(&fram_driver);				//移除iic设备return -1;}}printk("%s succeeded\n", DEVICE_NAME);return 0;
}//驱动接口-驱动出口函数-注销资源
static void __exit device_exit(void)
{printk("device_module_exit\n");i2c_del_driver(&fram_driver);				//移除iic设备cdev_del(&sg_fram->cd);						//注销字符设备驱动unregister_chrdev_region(sg_fram->devno, 1);	//注销设备号device_del(sg_fram->device);printk(KERN_INFO "delete device /dev/my_char_dev \n");class_destroy(sg_fram->device_class);printk(KERN_INFO "delete device /sys/class/my_char_dev \n");}module_init(device_init);
module_exit(device_exit);MODULE_LICENSE("GPL");
MODULE_AUTHOR("cp1300@139.com");

测试代码


void fram_test(void)
{int fd;u8 buff[512];int len;int i;fd = open("/dev/iic_fram", O_RDWR);if(fd < 0){printf("open iic_frame error:%d\r\n", fd);return ;}lseek(fd, 0, SEEK_SET);len = read(fd, buff, 32);if(len <= 0){printf("read iic_frame error:%d\r\n", fd);return ;}for(i = 0;i < len;i ++){printf("0x%02X \t", buff[i]);}printf("\r\n");//lseek(fd, 0, SEEK_SET);/*for(i = 0;i < len;i ++){buff[i] = i+0xF0;}len = write(fd, buff, len);if(len <= 0){printf("write iic_frame error:%d\r\n", fd);return ;}*/close(fd);}

读取32字节全部是0