Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

一、W25Q32BV芯片简介

        W25X是一系列SPI接口Flash芯片的简称,它采用SPI接口和CPU通信,本文使用的W25Q32BV容量为32M,具体特性如下:

1.1、基本特性

        该芯片最大支持104MHz的时钟,供电电压范围在2.7~3.6V,SPI的片选信号CS低有效,在操作芯片的时候,

需要将/WP和/HOLD管脚接电源。

        发送地址或数据到设备时,MOSI管脚数据采样在CLK的上升沿,从芯片读数据或者状态时,MISO管脚数据采样在CLK

的下降沿,所以在设置SPI的工作模式时,必须设置为MODE0或者MODE3,本文设置为MODE3。

1.2、存储空间简介

        W25Q32BV总共有16384页(page),每页有256bytes,每次最大可以编程一页。在擦除上,可以一次擦除

4KB、32KB、64KB,或者擦除整个芯片。整个芯片的存储空间如下图:

Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

        W25Q32BV存储空间分为sector和block。一个sector共有4KB,一个block共有32KB。一个sector存储空间如下图:

    Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

        本文共支持四种擦除方式,分别如下:

        1) cmd = 0x20,sector擦除,一次可以擦除4KB。芯片共有1024个sector。

        2) cmd = 0x52,半个block擦除,一次可以擦除32KB。芯片共有128个半block。

        3) cmd = 0xd8,block擦除,一次可以擦除64KB。芯片共有64个block。

        4) cmd = 0xC7,芯片擦除,擦除整个芯片。

1.3、状态寄存器

        W25Q32BV共有两个字节的状态寄存器,我们需要关心的就是BIT0和BIT1。

        BIT0:busy flag,1:busy,0:free。

        BIT1:write enable latch,1:write enable,0:write disable。

1.4、操作要求

        在操作W25Q32BV时,如果是写数据到芯片,则每写一个字节,都需要读取一个数据。

        在从芯片接收数据时,首先往芯片写一个字节的0xff,然后就是需要读取的数据。

二、设备驱动

2.1、设备注册

        在系统启动的时候,首先会对设备信息进行注册,见《Linux spi驱动分析(一)----总线驱动》中的3.1,所以编写w25q的设备
驱动程序时,首先需要对设备信息进行注册,具体内容如下:

点击(此处)折叠或打开

  1. #if defined(CONFIG_SPI_FLASH_W25Q)
  2.  static struct gsc3280_spi_info w25q_spi1_dev_platdata = {
  3.      .cs_type            = 1,
  4.     .pin_cs            = 87,
  5.     .num_cs            = 1,
  6.     .cs_value            = 0,
  7.     .lsb_flg            = 0,
  8.     .bits_per_word    = 8,
  9. };
  10. #endif
  11. static struct spi_board_info gsc3280_spi_devices[] = {
  12. #if defined(CONFIG_SPI_FLASH_W25Q)
  13.     {
  14.         .modalias        = "spi-w25q",
  15.         .bus_num        = 1,
  16.         .chip_select        = 2,
  17.         .mode            = SPI_MODE_3,
  18.         .max_speed_hz    = 5 * 1000 * 1000,
  19.         .controller_data    = &w25q_spi1_dev_platdata,
  20.     },
  21. #endif

  22. };
  23. static int __init gsc3280_spi_devices_init(void)
  24. {
  25.     spi_register_board_info(gsc3280_spi_devices, ARRAY_SIZE(gsc3280_spi_devices));
  26.     return 0;
  27. }
  28. device_initcall(gsc3280_spi_devices_init);

2.2、初始化函数

        首先我们从设备注册开始,程序如下:

点击(此处)折叠或打开

  1. static struct spi_driver w25q_driver = {
  2.     .driver    = {
  3.         .name    = "spi-w25q",
  4.         .owner    = THIS_MODULE,
  5.     },
  6.     //.id_table    = w25q_ids,
  7.     .probe    = w25q_probe,
  8.     .remove    = __devexit_p(w25q_remove),
  9. };


  10. static int __init w25q_init(void)
  11. {
  12.     return spi_register_driver(&w25q_driver);
  13. }
  14. static void __exit w25q_exit(void)
  15. {
  16.     spi_unregister_driver(&w25q_driver);
  17. }
  18. module_init(w25q_init);
  19. module_exit(w25q_exit);

        由于W25Q32BV使用SPI接口,所以将其注册为SPI驱动,接下来看下探测函数w25q_probe,程序如下:

点击(此处)折叠或打开

  1. static int __devinit w25q_probe(struct spi_device *spi)
  2. {
  3.     int ret = 0;
  4.     struct w25q_dev *w25q;

  5.     DBG("############\n");
  6.     DBG("w25q spi flash probe start.\n");
  7.     w25q = kzalloc(sizeof(struct w25q_dev), GFP_KERNEL);
  8.     if (!w25q) {
  9.         DBG("!!!!kzalloc error!\n");
  10.         return -ENOMEM;
  11.     }
  12.     ret = spi_setup(spi);
  13.     if (ret != 0) {
  14.         DBG("!!!!setup error!\n");
  15.         return ret;
  16.     }
  17.     w25q->spi = spi;
  18.     mutex_init(&w25q->mlock);
  19.     strlcpy(w25q->name, W25Q_SPI_FLASH_NAME, sizeof(w25q->name));
  20.     ret = alloc_chrdev_region(&w25q->devt, 0, W25Q_MAX_MINOR, "w25q");
  21.     if (ret < 0) {
  22.         DBG("!!!!%s: failed to allocate char dev region!\n", __FILE__);
  23.         goto err_kzall;
  24.     }
  25.     w25q->dev.devt = MKDEV(MAJOR(w25q->devt), 1);
  26.     cdev_init(&w25q->cdev, &w25q_fops);
  27.     w25q->cdev.owner = THIS_MODULE;
  28.     ret = cdev_add(&w25q->cdev, w25q->devt, 1);
  29.     if (ret) {
  30.         DBG("!!!!cdev add error!\n");
  31.         goto err_alloc;
  32.     }
  33.     w25q->class = class_create(THIS_MODULE, "w25q-spi");
  34.     if (IS_ERR(w25q->class)) {
  35.         DBG("!!!!failed in create w25q spi flash class!\n");
  36.         goto err_alloc;;
  37.     }
  38.     device_create(w25q->class, NULL, w25q->devt, NULL, "w25q");
  39.     dev_set_drvdata(&spi->dev, w25q);
  40.     DBG("w25q spi flash probe success.\n");
  41.     DBG("############\n");
  42.     return 0;

  43. err_alloc:
  44.     unregister_chrdev_region(w25q->devt, W25Q_MAX_MINOR);
  45. err_kzall:
  46.     kfree(w25q);
  47.     printk(KERN_ERR "!!!!!!w25q spi flash probe error.!!!!!!\n");
  48.     return ret;
  49. }

        说明:
        1) 首先申请设备驱动结构体。
        2) 调用spi_setup(spi)函数对设备信息初始化。
        3) 初始化设备驱动结构体成员变量。
        4) 创建/dev目录下操作文件,操作函数集为w25q_fops。
        5) 将设备驱动结构体中的链表插入本文件全局链表w25q_device_list中,以便在函数操作集的open函数中找到设备驱动结构体。
        remove函数是探测函数的相反过程,具体程序如下:

点击(此处)折叠或打开

  1. static int __devexit w25q_remove(struct spi_device *spi)
  2. {
  3.     struct w25q_dev *w25q = dev_get_drvdata(&spi->dev);

  4.     cdev_del(&w25q->cdev);
  5.     unregister_chrdev_region(w25q->devt, W25Q_MAX_MINOR);
  6.     device_destroy(w25q->class, w25q->devt);
  7.     class_destroy(w25q->class);
  8.     kfree(w25q);
  9.     return 0;
  10. }

2.3、操作函数集w25q_fops

        操作函数集结构体具体内容如下:

点击(此处)折叠或打开

  1. static const struct file_operations w25q_fops = {
  2.     .owner = THIS_MODULE,
  3.     .open = w25q_open,
  4.     .write = w25q_write,
  5.     .unlocked_ioctl = w25q_ioctl,
  6.     .read = w25q_read,
  7.     .llseek = w25q_llseek,
  8.     .release = w25q_release,
  9. };

        接下来我们一一讲述。
        首先看下open函数w25q_open,具体程序如下:

点击(此处)折叠或打开

  1. static int w25q_open(struct inode *inode, struct file *file)
  2. {
  3.     struct w25q_dev *w25q = container_of(inode->i_cdev, struct w25q_dev, char_cdev);

  4.     if (test_and_set_bit(W25Q_BIT_LOCK_OPEN, &w25q->bit_lock)) {
  5.         DBG("!!!!w25q open err, busy!\n");
  6.         return -EBUSY;
  7.     }
  8.     file->private_data = w25q;
  9.     return 0;
  10. }

        说明:
        1) 通过container_of找到在探测函数w25q_probe中定义的设备驱动结构体。
        2) 测试并且设置忙标志,如果测试忙,直接忙退出。
        3) 将找到的设备驱动结构体指针指向file->private_data,在函数操作集的其他函数中就可以使用设备驱动结构体了。
        接下来看下写函数w25q_write(),程序如下:

点击(此处)折叠或打开

  1. #define W25Q_BUF_LEN                4096
  2. #define W25Q_PAGE_NUM                256
  3. static ssize_t w25q_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos)
  4. {
  5.     int ret = 0;
  6.     u8 *buf_start, *buf_tmp, *w25q_buf;
  7.     struct w25q_dev *w25q= file->private_data;
  8.     u32 buf_size = 0, page_num = W25Q_PAGE_NUM, len = 0;
  9.     
  10.     DBG("@@@@w25q write start\n");
  11.     buf_start = buf_tmp = kzalloc(W25Q_BUF_LEN, GFP_KERNEL);
  12.     w25q_buf = w25q->buf = kzalloc(page_num + 4, GFP_KERNEL);
  13.     if (!buf_start || !w25q_buf) {
  14.         DBG("!!!!kzalloc error!\n");
  15.         return -ENOMEM;
  16.     }
  17.     ret = mutex_lock_interruptible(&w25q->mlock);
  18.     if (ret) {
  19.         DBG("!!!!mutex lock error!");
  20.         goto exit_kfree;
  21.     }
  22.     len = W25Q_BUF_LEN;
  23.     buf_size = min(count, len);
  24.     if (copy_from_user(buf_tmp, user_buf, buf_size)) {
  25.         DBG("!!!!copy_from_user() error!\n");
  26.         ret = -EFAULT;
  27.         goto exit_lock;
  28.     }
  29.     DBG("w25q->const_addr = 0x%x\n", w25q->const_addr);
  30.     buf_tmp = buf_start;
  31.     w25q->cmd = W25X_PAGE_PROG;
  32.     w25q->addr = w25q->const_addr;
  33.     while(buf_size) {
  34.         w25q->buf = w25q_buf;
  35.         w25q->len = min(buf_size, page_num);
  36.         memcpy(w25q->buf + 4, buf_tmp, w25q->len);
  37.         ret = w25q_write_date(w25q);
  38.         if (ret != 0) {
  39.             break;
  40.         }
  41.         buf_tmp += w25q->len;
  42.         w25q->addr += w25q->len;
  43.         buf_size -= w25q->len;
  44.     }

  45. exit_lock:
  46.     mutex_unlock(&w25q->mlock);
  47. exit_kfree:
  48.     kfree(buf_start);
  49.     kfree(w25q_buf);
  50.     if (ret != 0)
  51.         DBG("!!!!w25q write error!\n");
  52.     else
  53.         DBG("w25q write success\n");
  54.     return ret;
  55. }

        说明:
        1) 写函数首先申请两段内存,第一段内存用于存储从应用层复制来的待写数据,最大为4KB。第二段内存用于存储每次
            往W25Q32BV写的数据。由于W25Q32BV每次最大能写256bytes,所以page_num = 256,加上4是由于每次
            传输时,需要在最前面加上一个字节的命令和三个字节的地址。
        2) 获取本次可以传输的最大数据长度。
        3) 设置好传输的cmd和起始地址,然后进入while循环。
        4) 在while循环中,获取本次可以传输的最大长度,最长为256bytes,然后将其拷贝到buf中,加上4的目的是因为buf
            的前四个字节需要放置命令和地址。
        5) 调用w25q_write_date(w25q)函数实现数据传输。
        6) 更新变量,为下一次传输做好准备。
        w25q_write_date(w25q)函数具体内容如下:

点击(此处)折叠或打开

  1. static void w25q_write_enable(struct w25q_dev *w25q)
  2. {
  3.     u8 cmd = W25X_WRITE_ENABLE;

  4.     spi_w8r8(w25q->spi, cmd);
  5. }
  6. static int w25q_wait_null(struct w25q_dev *w25q)
  7. {
  8.     uint8_t limit = 5;

  9.     /* wait BUSY bit clear */
  10.     while(((w25q_read_stat_reg(w25q) & 0x01) == 0x01) && (limit != 0)) {
  11.         limit--;
  12.         mdelay(50);
  13.     }
  14.     if (limit == 0) {
  15.         DBG("!!!!w25q_wait_null:time out!\n");
  16.         return -EBUSY;
  17.     }
  18.     else
  19.         return 0;
  20. }
  21. /*
  22.  * when you call this function,
  23.  * the w25q->cmd, w25q->len(tx date len),
  24.  * w25q->addr and w25q->buf(date) are OK
  25.  *
  26.  */
  27. static int w25q_write_date(struct w25q_dev *w25q)
  28. {
  29.     int ret = 0;
  30.     u8 i = 0, rx = 0;
  31.     struct spi_message message;
  32.     struct spi_transfer    x[(w25q->len + 4) * 2];

  33.     w25q_write_enable(w25q);    //SET WEL
  34.     ret = w25q_wait_null(w25q);
  35.     if (ret != 0) {
  36.         DBG("!!!!w25q_write_date: wait null err!\n");
  37.         return ret;
  38.     }
  39.     if((w25q_read_stat_reg(w25q) & 0x02) != 0x02) {
  40.         DBG("!!!!state register write able is 0\n");
  41.         return -EBUSY;    //disable write
  42.     }

  43.     DBG("cmd = 0x%x, addr = 0x%x\n", w25q->cmd, w25q->addr);
  44.     w25q->buf[0] = w25q->cmd;
  45.     w25q->buf[1] = ((u8)(w25q->addr >> 16));
  46.     w25q->buf[2] = ((u8)(w25q->addr >> 8));
  47.     w25q->buf[3] = ((u8)w25q->addr);
  48.     
  49.     spi_message_init(&message);
  50.     memset(x, 0, sizeof x);
  51.     for (i = 0; i < (w25q->len + 4) * 2; i++) {
  52.         x[i].len = 1;
  53.         spi_message_add_tail(&x[i], &message);
  54.         if ((i % 2) == 0) {
  55.             x[i].tx_buf = w25q->buf++;
  56.         } else {
  57.             x[i].rx_buf = &rx;
  58.         }
  59.     }
  60.     /* do the i/o */
  61.     ret = spi_sync(w25q->spi, &message);
  62.     if (ret != 0) {
  63.         DBG("!!!!w25q_write_date: spi_sync() error!");
  64.         return ret;
  65.     }
  66.     ret = w25q_wait_null(w25q);
  67.     if (ret != 0)
  68.         DBG("!!!!w25q_write_date: w25q_wait_null() error!");
  69.     return ret;
  70. }

        说明:
        1) 在调用w25q_write_date(w25q)函数之前,需要首先设置好w25q->cmd, w25q->len(tx date len)
            w25q->addr和w25q->buf(date)变量。
        2) 设置芯片状态寄存器,使其可写。
        3) 等待芯片不忙。
        4) 读取芯片状态寄存器,查看其是否可写。
        5) 配置发送buf,调用spi_sync(w25q->spi, &message);函数实现写数据。
        6) 等待芯片不忙,退出。
        接下来看下函数操作集中的ioctl函数,程序如下:

点击(此处)折叠或打开

  1. static long w25q_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  2. {
  3.     int ret = 0;
  4.     u32 get_value = 0;
  5.     struct w25q_dev *w25q= file->private_data;
  6.     void __user *argp = (void __user *)arg;
  7.     int __user *p = argp;

  8.     DBG("@@@@w25q ioctl start.\n");
  9.     ret = mutex_lock_interruptible(&w25q->mlock);
  10.     if (ret) {
  11.         DBG("!!!!mutex lock error!\n");
  12.         return ret;
  13.     }
  14.     if ((_IOC_TYPE(cmd) != W25Q_IOC_MAGIC) || (_IOC_NR(cmd) > W25Q_IOC_MAXNR)) {
  15.         DBG("!!!!ioc type or ioc nr error!\n");
  16.         ret = -ENOTTY;
  17.         goto exit;
  18.     }
  19.     switch(cmd) {
  20.     case W25Q_SECTOR_ERASE:
  21.     case W25Q_HALF_BLOCK_ERASE:
  22.     case W25Q_BLOCK_ERASE:
  23.         if (get_user(get_value, p)) {
  24.             DBG("!!!!get value error!\n");
  25.             ret = -EFAULT;
  26.             goto exit;
  27.         }
  28.         ret = w25q_erase(w25q, get_value, cmd);
  29.         break;
  30.     case W25Q_CHIP_ERASE:
  31.         ret = w25q_chip_erase(w25q);
  32.         break;
  33.     case W25Q_READ_DEVICE_ID:
  34.         ret = w25q_read_id(w25q);
  35.         if (ret == 0)
  36.             put_user(w25q->result, p);
  37.         break;
  38.     default:
  39.         DBG("!!!!cmd error!\n");
  40.         ret = -ENOTTY;
  41.         break;
  42.     }

  43. exit:
  44.     mutex_unlock(&w25q->mlock);
  45.     if (ret != 0)
  46.         DBG("!!!!w25q ioctl error!\n");
  47.     else
  48.         DBG("w25q ioctl success.\n");
  49.     return ret;
  50. }

        说明:
        1) 目前共支持5个命令,包括sector擦除,half block擦除,block擦除,芯片擦除和读取芯片ID。
        2) 前三种擦除方式共用一个函数w25q_erase(w25q, get_value, cmd);,程序如下:

点击(此处)折叠或打开

  1. static int w25q_erase(struct w25q_dev *w25q, u32 num, unsigned int cmd)
  2. {
  3.     int ret = 0;
  4.     u8 *buf_start;

  5.     switch(cmd) {
  6.     case W25Q_SECTOR_ERASE:
  7.         DBG("sector erase cmd\n");
  8.         if (num > W25Q_SECTOR_MAX) {
  9.             DBG("!!!!sector max is over\n");
  10.             return -EFAULT;
  11.         }
  12.         w25q->const_addr = num * W25Q_ONE_SECTOR_ADDR;
  13.         w25q->cmd = W25X_SECTOR_ERASE_CMD;
  14.         break;
  15.     case W25Q_HALF_BLOCK_ERASE:
  16.         DBG("half block erase cmd\n");
  17.         if (num > W25Q_HALF_BLOCK_MAX) {
  18.             DBG("!!!!half block max is over\n");
  19.             return -EFAULT;
  20.         }
  21.         w25q->const_addr = num * W25Q_HALF_BLOCK_ADDR;
  22.         w25q->cmd = W25X_HALF_BLOCK_ERASE_CMD;
  23.         break;
  24.     case W25Q_BLOCK_ERASE:
  25.         DBG("block erase cmd\n");
  26.         if (num > W25Q_BLOCK_MAX) {
  27.             DBG("!!!!block max is over\n");
  28.             return -EFAULT;
  29.         }
  30.         w25q->const_addr = num * W25Q_ONE_BLOCK_ADDR;
  31.         w25q->cmd = W25X_BLOCK_ERASE_CMD;
  32.         break;
  33.     }
  34.     DBG("w25q->const_addr = 0x%x\n", w25q->const_addr);
  35.     w25q->len = 0;
  36.     buf_start = w25q->buf = kzalloc(w25q->len + 4, GFP_KERNEL);
  37.     if (!buf_start) {
  38.         DBG("!!!!kzalloc is error\n");
  39.         return -ENOMEM;
  40.     }
  41.     w25q->addr = w25q->const_addr;
  42.     ret = w25q_write_date(w25q);
  43.     kfree(buf_start);
  44.     if (ret != 0) {
  45.         DBG("!!!!w25q_erase: spi write err!\n");
  46.         return ret;
  47.     }
  48.     DBG("w25q_erase: erase OK\n");
  49.     return ret;
  50. }

        说明:
        1) 首先根据不同的擦除方式,设置命令和地址两个变量。
        2) 调用w25q_write_date(w25q);函数实现数据传输。
        芯片擦除函数w25q_chip_erase()如下:

点击(此处)折叠或打开

  1. static int w25q_chip_erase(struct w25q_dev *w25q)
  2. {
  3.     int ret = 0;
  4.     u8 cmd = W25X_CHIP_ERASE;

  5.     DBG("w25q_chip_erase\n");
  6.     w25q_write_enable(w25q);    //SET WEL
  7.     ret = w25q_wait_null(w25q);
  8.     if (ret != 0) {
  9.         DBG("!!!!chip_erase: wait null err!\n");
  10.         return ret;
  11.     }
  12.     if((w25q_read_stat_reg(w25q) & 0x02) != 0x02) {
  13.         DBG("!!!!state register write able is 0\n");
  14.         return -EBUSY;    //disable write
  15.     }
  16.     spi_w8r8(w25q->spi, cmd);
  17.     return w25q_wait_null(w25q);
  18. }

        读取设备ID函数w25q_read_id()如下:

点击(此处)折叠或打开

  1. static int w25q_read_id(struct w25q_dev *w25q)
  2. {
  3.     int ret = 0;
  4.     u8 *buf_start;

  5.     DBG("w25q_read_id\n");
  6.     w25q->len = 2;
  7.     w25q->addr = 0;
  8.     w25q->cmd = W25X_READ_ID_CMD;
  9.     buf_start = w25q->buf = kzalloc(w25q->len, GFP_KERNEL);
  10.     if (!buf_start) {
  11.         DBG("!!!!kzalloc is error\n");
  12.         return -ENOMEM;
  13.     }
  14.     ret = w25q_read_data(w25q);
  15.     w25q->buf = buf_start;
  16.     w25q->result = *w25q->buf << 8;
  17.     w25q->buf++;
  18.     w25q->result |= *w25q->buf;
  19.     kfree(buf_start);
  20.     if (ret != 0) {
  21.         DBG("!!!!w25q_read_id: w25q_read_data error!\n");
  22.         return ret;
  23.     }
  24.     DBG("w25q_read_id: read id OK\n");
  25.     return ret;
  26. }

        说明:
        1) 首先设置好变量,申请内存
        2) 调用w25q_read_data()函数实现读取数据。
        w25q_read_data函数如下:

点击(此处)折叠或打开

  1. /*
  2.  * when you call this function,
  3.  * the w25q->cmd, w25q->len(receive len)
  4.  * w25q->buf(kzalloc receive) and w25q->addr are OK
  5.  *
  6.  */
  7. static int w25q_read_data(struct w25q_dev *w25q)
  8. {
  9.     int ret = 0;
  10.     struct spi_message message;
  11.     struct spi_transfer    x[(w25q->len + 4) * 2];
  12.     u8 i = 0, rx = 0, dumy_value = 0xff, tx_buff[4] = {0};

  13.     w25q_write_enable(w25q);    //SET WEL
  14.     ret = w25q_wait_null(w25q);
  15.     if (ret != 0) {
  16.         DBG("!!!!chip_erase: wait null err!\n");
  17.         return ret;
  18.     }
  19.     if((w25q_read_stat_reg(w25q) & 0x02) != 0x02) {
  20.         DBG("!!!!state register write able is 0\n");
  21.         return -EBUSY;    //disable write
  22.     }

  23.     DBG("cmd = 0x%x, addr = 0x%x\n", w25q->cmd, w25q->addr);
  24.     tx_buff[0] = w25q->cmd;
  25.     tx_buff[1] = ((uint8_t)(w25q->addr >> 16));
  26.     tx_buff[2] = ((uint8_t)(w25q->addr >> 8));
  27.     tx_buff[3] = ((uint8_t)(w25q->addr));
  28.     
  29.     spi_message_init(&message);
  30.     memset(x, 0, sizeof x);
  31.     for (i = 0; i < 8; i++) {    //cmd
  32.         x[i].len = 1;
  33.         spi_message_add_tail(&x[i], &message);
  34.         if ((i % 2) == 0) {
  35.             x[i].tx_buf = &tx_buff[i / 2];
  36.         } else {
  37.             x[i].rx_buf = &rx;
  38.         }
  39.     }
  40.     for (i = 8; i < (w25q->len + 4) * 2; i++) {
  41.         x[i].len = 1;
  42.         spi_message_add_tail(&x[i], &message);
  43.         if ((i % 2) == 0) {
  44.             x[i].tx_buf = &dumy_value;
  45.         } else {
  46.             x[i].rx_buf = w25q->buf++;
  47.         }
  48.     }
  49.     /* do the i/o */
  50.     return spi_sync(w25q->spi, &message);
  51. }

        说明:
        1) 在从芯片读取数据时的格式为:首先发送一个字节命令+三个字节读取地址,然后就可以接收数据了。
        2) 第一个for循环发送的是命令和地址,第二个for循环是接收数据。
        3) 调用此函数之前,需要设置好w25q->cmd, w25q->len(receive len),w25q->buf(kzalloc receive)和w25q->addr。
        接下来看下函数操作集中的读数据函数w25q_read(),程序如下:

点击(此处)折叠或打开

  1. static ssize_t w25q_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos)
  2. {
  3.     int ret = 0;
  4.     u8 *buf_start, *buf_tmp, *w25q_buf;
  5.     struct w25q_dev *w25q = file->private_data;
  6.     u32 buf_size = 0, read_len = 0, page_num = W25Q_PAGE_NUM;

  7.     DBG("@@@@w25q read start\n");
  8.     buf_start = buf_tmp = kzalloc(W25Q_BUF_LEN, GFP_KERNEL);
  9.     w25q_buf = w25q->buf = kzalloc(page_num, GFP_KERNEL);
  10.     if (!buf_start || !w25q_buf ) {
  11.         DBG("!!!!kzalloc error!\n");
  12.         return -ENOMEM;
  13.     }
  14.     ret = mutex_lock_interruptible(&w25q->mlock);
  15.     if (ret) {
  16.         DBG("!!!!mutex lock error!\n");
  17.         goto exit_kfree;
  18.     }
  19.     read_len = W25Q_BUF_LEN;
  20.     buf_size = min(count, read_len);
  21.     read_len = buf_size;
  22.     
  23.     w25q->cmd = W25X_READ_DATA;
  24.     w25q->addr = w25q->const_addr;
  25.     DBG("w25q->addr = 0x%x\n", w25q->addr);
  26.     while (buf_size) {
  27.         w25q->buf = w25q_buf;
  28.         w25q->len = min(buf_size, page_num);
  29.         ret = w25q_read_data(w25q);
  30.         if (ret != 0) {
  31.             goto exit_lock;
  32.         }
  33.         memcpy(buf_tmp, w25q_buf, w25q->len);
  34.         buf_tmp += w25q->len;
  35.         buf_size -= w25q->len;
  36.         w25q->addr += w25q->len;
  37.     }
  38.     ret = copy_to_user(user_buf, buf_start, read_len);
  39.     ret = read_len -ret;

  40. exit_lock:
  41.     mutex_unlock(&w25q->mlock);
  42. exit_kfree:
  43.     kfree(buf_start);
  44.     kfree(w25q_buf);
  45.     DBG("w25q read stop, ret = %d\n", ret);
  46.     return ret;
  47. }

        说明:
        1) 此函数需要申请两段内存空间,第一段用于存放从W25Q32BV接收到的数据,第二段用于存放每次接收的数据。
        2) 设置好变量后,调用w25q_read_data(w25q)读取数据。
        3) 读取完成后,将读取到的数据拷贝到应用层。

三、应用层测试

        应用层测试程序如下:

点击(此处)折叠或打开

  1. /*
  2. * first you must erase,
  3. * then write, then read
  4. * or you can read only
  5. *
  6. */
  7. #include "w25q.h"


  8. int main(int argc, char **argv)
  9. {
  10.     char str[10] = {0};
  11.     int fd = 0, ret = 0;
  12.     unsigned char buffer[BUFSIZE] = {0};
  13.     unsigned int i = 0, idCmd = 0, num = 0;
  14.     
  15.     fd = open("/dev/w25q", O_RDWR);
  16.     if (fd < 0) {
  17.         printf("Open ADC Device Faild!\n");
  18.         exit(1);
  19.     }
  20.     while(1) {
  21.         idCmd = 0;
  22.         printf("please enter the cmd and num :\n");
  23.         scanf("%s%x", str, &num);
  24.         //printf("cmd = %s, idFreq = %d\n", str, idFreq);
  25.         if (num >= 0) {
  26.             if (strcmp(str, "SECTOR") == 0) {
  27.                 idCmd = W25Q_SECTOR_ERASE;
  28.                 ret = ioctl(fd, idCmd, &num);
  29.                 if (ret != 0) {
  30.                     printf("sector erase Faild!\n");
  31.                 }
  32.             } else if(strcmp(str, "HALF") == 0) {
  33.                 idCmd = W25Q_HALF_BLOCK_ERASE;
  34.                 ret = ioctl(fd, idCmd, &num);
  35.                 if (ret != 0) {
  36.                     printf("half block erase Faild!\n");
  37.                 }
  38.             } else if(strcmp(str, "BLOCK") == 0) {
  39.                 idCmd = W25Q_BLOCK_ERASE;
  40.                 ret = ioctl(fd, idCmd, &num);
  41.                 if (ret != 0) {
  42.                     printf("block erase Faild!\n");
  43.                 }
  44.             } else if(strcmp(str, "CHIP") == 0) {
  45.                 idCmd = W25Q_CHIP_ERASE;
  46.                 ret = ioctl(fd, idCmd, &num);
  47.                 if (ret != 0) {
  48.                     printf("chip erase Faild!\n");
  49.                 }
  50.             } else if(strcmp(str, "ID") == 0) {
  51.                 idCmd = W25Q_READ_DEVICE_ID;
  52.                 ret = ioctl(fd, idCmd, &num);
  53.                 if (ret != 0) {
  54.                     printf("read ID Faild!\n");
  55.                 } else {
  56.                     printf("ID = 0x%x\n", num);
  57.                 }
  58.             } else if(strcmp(str, "READ") == 0) {
  59.                 memset(buffer, 0, BUFSIZE);
  60.                 printf("------------\n");
  61.                 for (i = 0; i < WRITE_NUM; i++) {
  62.                     if((i != 0) && ((i % 8) == 0)) {
  63.                         printf("\n");
  64.                     }
  65.                     printf("0x%x ", buffer[i]);
  66.                 }
  67.                 printf("\n------------\n");
  68.                 ret = read(fd, buffer, WRITE_NUM);
  69.                 printf("\n------------\n");
  70.                 for (i = 0; i < WRITE_NUM; i++) {
  71.                     if((i != 0) && ((i % 8) == 0)) {
  72.                         printf("\n");
  73.                     }
  74.                     printf("0x%x ", buffer[i]);
  75.                 }
  76.                 printf("\n------------\n");
  77.             } else if(strcmp(str, "WRITE") == 0) {
  78.                 for (i = 0; i < WRITE_NUM; i++) {
  79.                     buffer[i] = i;
  80.                 }
  81.                 ret = write(fd, buffer, WRITE_NUM);
  82.                 if (ret != 0) {
  83.                     printf("w25q write oper Faild!\n");
  84.                 }
  85.             } else if(strcmp(str, "QUIT") == 0) {
  86.                 break;
  87.             } else {
  88.                 printf("wrong string\n");
  89.             }
  90.         } else {
  91.             printf("wrong input num(< 0)\n");
  92.         }
  93.     }/* end while(1) */
  94.     close(fd);
  95.     return 0;
  96. }

        说明:
        1) 首先从终端接收命令内容。
        2) 比较命令,然后进入不同的处理流程。

四、测试演示

4.1、读取芯片ID

Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

4.2、读写芯片

Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV),布布扣,bubuko.com

Linux spi驱动分析(四)----SPI设备驱动(W25Q32BV)

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