I2C总线的EEPROM（24C08）Linux驱动
来源：互联网 发布：马克斯cms x站模板 编辑：程序博客网 时间：2024/06/05 07:55
基于Linux 2.6.30内核
来源：http://blog.csdn.net/terminalnt/article/details/6582577
符合Linux驱动架构模型
针对24C08的Page读写做了优化。
完全模拟文件读写方式，支持lseek操作。
这个代码中，包含了设备的地址，在i2c_add_driver时会去探测该地址上是否有设备。
但通常，做板级开发时，i2c_device被放在board文件的i2c_registry中，
i2c_device和i2c_driver根据name字段来匹配。
转载请注明出处
代码原创
注：更新的Linux版本内核中，i2c_driver结构体有少许的变化。
/* * eeprom-24c08.c - eeprom driver for some mostly-compatible I2C chips. * * Copyright (C) 2011 William Smith * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/i2c.h> //#include <linux/bcd.h> /*New Add */ #include <linux/cdev.h> #include <arm-asm/uaccess.h> #include <linux/fs.h> #include <linux/device.h> #define EEP_MAJOR 236 /* Major number can also be dynamically allocated. */ #define BNK_SIZE 1024 /* BANK SIZE */ #define BLK_SIZE 256 /* BLOCK SIZE */ #define PG_SIZE 16 /* PAGE SIZE */ #define EEPROM_SLAVE_ADDR0 0x50 /* 7bit. Binary: 1010000 */ #define EEPROM_SLAVE_ADDR1 0x51 /* 7bit. Binary: 1010001 */ #define EEPROM_SLAVE_ADDR2 0x52 /* 7bit. Binary: 1010010 */ #define EEPROM_SLAVE_ADDR3 0x53 /* 7bit. Binary: 1010011 */ #define MAX_RETRYS 30 /* For DEBUG */ //#define DEBUG_EEP #define DEBUG_EEP_R static int max_retrys_record = 0; static struct eep_24c08 { struct i2c_client *client[4]; /* I2C client for this eeprom */ struct cdev eep_cdev; /* cdev */ dev_t dev_num; /* dev num */ unsigned int cur_ptr; /* Current File pointer */ } *eep; static int eep_open (struct inode *inode, struct file *file) { #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM open\n"); #endif max_retrys_record = 0; eep->cur_ptr = 0; return 0; } static int eep_release (struct inode *inode, struct file *file) { #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM close\n"); #endif return 0; } static loff_t eep_llseek(struct file *filp, loff_t off, int whence) { #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM lseek\n"); #endif switch(whence) { case 0: /* SEEK_SET */ eep->cur_ptr = off; break; case 1: /* SEEK_CUR */ eep->cur_ptr += off; break; case 2: /* SEEK_END */ eep->cur_ptr = BNK_SIZE + off; break; default: /* can't happen */ return -EINVAL; } if ((eep->cur_ptr < 0) || (eep->cur_ptr > BNK_SIZE)) { printk(KERN_ALERT "EEPROM 'lseek()' call, param mistake\n"); eep->cur_ptr = 0; return -1; } return eep->cur_ptr; } static int __rw_page(char *buf, int length, int rw) { int ret,err=0; int block; unsigned char word_addr; struct i2c_adapter *adap; struct i2c_msg msg[2]; int msg_num; unsigned char *buf_tmp=NULL; block = eep->cur_ptr / BLK_SIZE; adap = eep->client[block]->adapter; word_addr = eep->cur_ptr % BLK_SIZE; #ifdef DEBUG_EEP printk(KERN_ALERT "__rw_page(): %s: client[%d]->addr = 0x%02X, cur_ptr = %d, block = %d, word_addr = %d\n", (rw?"write":"read"), block, eep->client[block]->addr, eep->cur_ptr, block, word_addr); #endif if(rw) { /* write data */ /* alloc memory for buf_tmp */ buf_tmp = kmalloc(length+1, GFP_KERNEL); if (!buf_tmp) { printk(KERN_ALERT "EEPROM kmalloc %d failed\n", length+1); return -ENOMEM; } memcpy(buf_tmp+1, buf, length); buf_tmp[0] = word_addr; msg[0].addr = eep->client[block]->addr; msg[0].flags = 0; msg[0].len = length+1; msg[0].buf = buf_tmp; } else { /* read data */ msg[0].addr = eep->client[block]->addr; msg[0].flags = 0; msg[0].len = 1; msg[0].buf = &word_addr; msg[1].addr = eep->client[block]->addr; msg[1].flags = I2C_M_RD; msg[1].len = length; msg[1].buf = buf; } msg_num = rw?1:2; #ifdef DEBUG_EEP printk(KERN_ALERT "msg_num = %d, msg[0]: addr = 0x%02X, flags = %d, len = %d, buf[0~3] = %02X,%02X,%02X,%02X\n", msg_num, msg[0].addr, msg[0].flags, msg[0].len, msg[0].buf[0], msg[0].buf[1], msg[0].buf[2], msg[0].buf[3]); #endif ret = i2c_transfer(adap, msg, msg_num); if (ret<0) { #ifdef DEBUG_EEP printk(KERN_ALERT "i2c_transfer() err %d\n", ret); #endif err = ret; goto exit; } else if (ret<(rw?1:2)) { printk(KERN_ERR "__rw_page(): %s: error, actual write i2c_msg number %d, desire i2c_msg number %d\n", (rw?"write":"read"), ret, (rw?1:2)); err = -EIO; goto exit; } exit: if (rw) kfree(buf_tmp); return (err?err:length); } static int rw_page(char *buf, int length, int rw) { int i; int ret,err=0; char *buf_tmp; /* alloc memory for buf_tmp */ buf_tmp = kmalloc(length, GFP_KERNEL); if (!buf_tmp) { printk(KERN_ALERT "EEPROM kmalloc %d failed\n", length); return -ENOMEM; } for (i=0;i<MAX_RETRYS;i++) { ret = __rw_page(buf, length, rw); if (ret<0) continue; ret = __rw_page(buf_tmp, length, 0); if (ret<0) continue; ret = memcmp(buf, buf_tmp, length); if (ret == 0) break; else { #ifdef DEBUG_EEP printk(KERN_ALERT "rw_page(): %s : memcmp return %d\n", (rw?"write":"read"), ret); printk(KERN_ALERT "Original buf: "); for (i=0;i<length;i++) printk(KERN_ALERT "%02X ", buf[i]); printk(KERN_ALERT "\nRecheck buf: "); for (i=0;i<length;i++) printk(KERN_ALERT "%02X ", buf_tmp[i]); printk(KERN_ALERT "\n"); #endif } } #ifdef DEBUG_EEP_R if (i) { printk(KERN_ALERT "Retry %d times.\n", i); if (i > max_retrys_record) max_retrys_record = i; } #endif if (i == MAX_RETRYS) { printk(KERN_ALERT "Reach MAX_RETRYS(%d times) limit.\n", MAX_RETRYS); err = -EAGAIN; goto exit; } exit: kfree(buf_tmp); return (err?err:length); } static ssize_t eep_rw (char *buf, size_t count, int rw) { int ret,err=0; int length = count; int seg; char *buf_tmp=NULL, *buf_cur; #ifdef DEBUG_EEP printk(KERN_ALERT "###### eep_rw(), buf=%p, count=%d, rw=%d ######\n", buf, count, rw); #endif /* Check param */ if (eep->cur_ptr + count > BNK_SIZE) { printk(KERN_ALERT "EEPROM Try to %s over BNK_SIZE: \n" "\tcur_ptr = %d, count = %d, cur_ptr+count = %d\n", (rw?"write":"read"), eep->cur_ptr, count, eep->cur_ptr + count); return -EINVAL; } if (rw != 0 && rw != 1) { printk(KERN_ALERT "eep_rw() error, rw param value %d invalid.\n", rw); return -EINVAL; } /* alloc memory for buf_tmp */ buf_tmp = kmalloc(count, GFP_KERNEL); if (!buf_tmp) { printk(KERN_ALERT "EEPROM kmalloc %d failed\n", count); return -ENOMEM; } buf_cur = buf_tmp; if (rw == 1) copy_from_user(buf_tmp, (const char *)buf, count); while(length > 0) { seg = length>PG_SIZE? PG_SIZE: length; #ifdef DEBUG_EEP printk(KERN_ALERT "eep_rw(): %s: count = %d, cur_ptr = %d, seg = %d, length = %d\n", (rw?"write":"read"), count, eep->cur_ptr, seg, length); #endif ret = rw_page(buf_cur, seg, rw); if (ret<0) { printk(KERN_ALERT "EEPROM %s error %d\n", (rw?"write":"read"), ret); err = ret; goto exit; } buf_cur += seg; length -= seg; eep->cur_ptr += seg; } if (rw == 0) copy_to_user(buf, (const char *)buf_tmp, count); #ifdef DEBUG_EEP_R printk(KERN_ALERT "Max retrys record is %d\n", max_retrys_record); #endif exit: kfree(buf_tmp); return (err?err:count); } static ssize_t eep_read (struct file *file, char __user *buf, size_t count, loff_t *ppos) { return eep_rw(buf, count, 0); } static ssize_t eep_write (struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return eep_rw(buf, count, 1); } static struct file_operations eep_fops = { .owner = THIS_MODULE, .open = eep_open, .release = eep_release, .llseek = eep_llseek, .read = eep_read, .write = eep_write, }; static const unsigned short normal[] = { EEPROM_SLAVE_ADDR0, EEPROM_SLAVE_ADDR1, EEPROM_SLAVE_ADDR2, EEPROM_SLAVE_ADDR3, I2C_CLIENT_END }; static const unsigned short ignore[] = { I2C_CLIENT_END }; static const struct i2c_client_address_data eep_addr_data = { .normal_i2c = normal, .forces = NULL, .probe = ignore, .ignore = ignore, }; /* The higher version of Linux kernel is much more simple. */ /* The device name this driver supported. */ static const struct i2c_device_id eep_24c08_id[] = { { "eeprom-blk0", EEPROM_SLAVE_ADDR0 }, { "eeprom-blk1", EEPROM_SLAVE_ADDR1 }, { "eeprom-blk2", EEPROM_SLAVE_ADDR2 }, { "eeprom-blk3", EEPROM_SLAVE_ADDR3 }, { } }; /* Well, there is some necessary to take a explaination. * Because of the device 24C08 has 8K bits in it, it need 4 addresses. * In the I2C protocal, the SLAVE_ADDR data has only 8 bit, which could only address 256 Bytes(2048 bits). * So 24C08 has 4 different SLAVE_ADDR addresses: 0x50, 0x51, 0x52, 0x53. * Each address is a part that has 2048 bits. Totally, 4 parts have 8192 bits(8K bits). */ MODULE_DEVICE_TABLE(i2c, eep_24c08_id); /* eep_probe - probe method for new-style driver model. * @client: the i2c_client which already been register. * @id: the i2c_device_id which matchs. * When dev and driver are both create and matched. This func will be called to init some specfic data. * Usually, the device's initial step will be done here. * Note: When a driver has N devices, the probe will be called N times. * For different device, different i2c_device_id will be provided for use in the probe function. */ static int __devinit eep_probe(struct i2c_client *client, const struct i2c_device_id *id) { int i=0; #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM probe\n"); #endif while (eep_24c08_id[i].driver_data) { if (client->addr == (unsigned short)eep_24c08_id[i].driver_data) { #ifdef DEBUG_EEP printk(KERN_ALERT "probe(): client->addr = 0x%02X, i = %d, eep_24c08_id[%d].driver_data = 0x%02X, eep_24c08_id[%d].name = %s\n", client->addr, i, i, (unsigned int)eep_24c08_id[i].driver_data, i, eep_24c08_id[i].name); #endif eep->client[i] = client; /* Store the client into eep for further use. */ /* client can also be stored in file->p when open(). */ } i++; } return 0; } static int __devexit eep_remove(struct i2c_client *client) { #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM remove\n"); #endif return 0; } /* eep_detect - detect method is called when there is really some device on '@kind' address. @i2c_client: the temp client device which is given to detect func's use. It is only temp which has not been register. @kind: indicate the number in i2c_client_address_data for each possible member. only for forces device. Others condition is -1. @i2c_board_info: the specific infomation's structure to store device's info. * This function was called before the real i2c_client is create. * Some special device need a initializion before read/write it, do the init here. * Init the client's infomation, and it need to fill at least the name * of i2c_board_info param for registering which is also the name of client device. * Notice: Its addr member has already beed set. */ int eep_detect(struct i2c_client *client, int kind, struct i2c_board_info *bd_info) { int i=0; #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM detect\n"); #endif /* There is no need to take action of detect on I2C bus. */ while (eep_24c08_id[i].driver_data) { if (client->addr == (unsigned short)eep_24c08_id[i].driver_data) { strlcpy(bd_info->type, eep_24c08_id[i].name, I2C_NAME_SIZE); /* In fact, giving the name is the only thing need to do. */ bd_info->flags = 0; #ifdef DEBUG_EEP printk(KERN_ALERT "detect(): i = %d, client->addr = 0x%02X, bd_info->type = %s\n", i, client->addr, bd_info->type); #endif } i++; } /* platform_data should be study later */ return 0; } static struct i2c_driver eep_driver = { .driver = { .name = "eeprom-driver", /* Name */ .owner = THIS_MODULE, }, .class = 1, .probe = eep_probe, .remove = __devexit_p(eep_remove), .id_table = eep_24c08_id, .detect = eep_detect, .address_data = &eep_addr_data, }; static int __init eeprom_init(void) { int err=0; eep = kmalloc(sizeof(struct eep_24c08), GFP_KERNEL); if (!eep) { err = -ENOMEM; goto exit; } /* Get and register the cdev for eeprom */ eep->dev_num = MKDEV(EEP_MAJOR,0); if (register_chrdev_region(eep->dev_num, 1, "eeprom") <0 ) { printk(KERN_ALERT "Can't register device\n"); goto exit_free; } cdev_init(&eep->eep_cdev, &eep_fops); eep->eep_cdev.owner = THIS_MODULE; eep->eep_cdev.ops = &eep_fops; if (cdev_add(&eep->eep_cdev, eep->dev_num, 1)) { printk(KERN_ALERT "Failed to add cdev of EEPROM\n"); goto exit_unregister; } /* Register i2c_driver to i2c core */ err = i2c_add_driver(&eep_driver); if (err) { printk(KERN_ALERT "Registering I2C driver of EEPROM failed, errno is %d\n", err); goto exit_del_cdev; } #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM Driver Initialized.\n"); #endif return 0; exit_del_cdev: cdev_del(&eep->eep_cdev); exit_unregister: unregister_chrdev_region(eep->dev_num, 1); exit_free: kfree(eep); exit: return err; } static void __exit eeprom_exit(void) { i2c_del_driver(&eep_driver); cdev_del(&eep->eep_cdev); unregister_chrdev_region(eep->dev_num, 1); kfree(eep); #ifdef DEBUG_EEP printk(KERN_ALERT "EEPROM Driver Removed.\n"); #endif } module_init(eeprom_init); module_exit(eeprom_exit); MODULE_DESCRIPTION("EEPROM driver for 24C08 and similar chips"); MODULE_LICENSE("GPL"); 来源：http://blog.csdn.net/terminalnt/article/details/6582577
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