[Linux] 核心中 SPI 裝置驅動模型（Platform裝置驅動方式）

傳統 Platform裝置驅動方式 中 SPI 驅動模型

#include <linux/module.h>
#include <linux/spi/spi.h>

#define DEVICE_NAME   "sensor"
#define SENSOR_SPI_BUS 0
struct spi_device *sensor_spi = NULL;

int sensor_spi_write(void)
{
    // 調用平台的接口實作 spi_write
    return ;
}

int sensor_spi_read(void)
{
    // 調用平台的接口實作 spi_read
    return ;
}


static const struct spi_device_id sensor_spi_id[] = {
    { DEVICE_NAME,  },
    { }
};

MODULE_DEVICE_TABLE(spi, sensor_spi_id);

static int  sensor_probe(struct spi_device *spi)
{
    sensor_spi = spi;
    return ;
}

static int  sensor_remove(struct spi_device *spi)
{
    return ;
}

static struct spi_driver sensor_driver = {
    .driver = {
        .name  = DEVICE_NAME,
        .owner = THIS_MODULE,
    },
    .probe    =  sensor_probe,
    .remove   =  sensor_remove,
    .id_table =  sensor_spi_id,
};

static __init int sensor_spi_init(void)
{
    int status=-;
    struct spi_master *master;
    struct spi_device *spi;
    struct spi_board_info chip =
    {
        .modalias     = DEVICE_NAME,
        .mode         = ,
        .bus_num      = ,
        .chip_select  = ,
        .max_speed_hz = ,
    };
    spi_register_driver(&sensor_driver);
    if (status<)
    {
        pr_err("%s: spi_register_driver spi_driver failure. status = %d\n", __func__, status);
    }
    pr_err("%s: spi_register_driver spi_driver success. status = %d\n", __func__, status);
    master = spi_busnum_to_master(SENSOR_SPI_BUS);
    if (!master)
    {
        status = -ENODEV;
        goto error_busnum;
    }
    spi = spi_new_device(master, &chip);
    if (!spi)
    {
        status = -EBUSY;
        goto error_mem;
    }
    return status;

error_mem:
error_busnum:
    spi_unregister_driver(&sensor_driver);
    return status;
}

static __exit void sensor_spi_exit(void)
{
    spi_unregister_driver(&sensor_driver);
    if(sensor_spi!=NULL)
    spi_unregister_device(sensor_spi);
}

module_init(sensor_spi_init);
module_exit(sensor_spi_exit);
MODULE_LICENSE("GPL");
           

這是 3.2 版本之前的核心裡spi驅動的模型。

歸納一下:

1. 先注冊 spi_board_info 結構體
2. 比對 spi_master,
3. 建立 spi_device.
4. 建立完裝置之後再到 spi 總線上尋找有沒有同名的spi_driver. 如果有的話就調用 spi_drive r的 probe 函數.
5. 在 probe 函數裡 register_chrdev/class_create/device_create, 建立 chrdev 然後通過 fops 裡的函數來讀寫 spi 裝置.