linux spi驱动源码

1. SPI裸板程序 1.1 用GPIO模拟SPI 1.2 用S3C2440的SPI控制器 2.SPI驱动框架 2.1 枚举过程 drivers/spi/spi.c: spi_register_board_info /* 对于每一个spi_master,调用spi_match_master_to_boardinfo */ list_for_each_entry(master, &spi_master_list, list) spi_match_master_to_boardinfo /* board_info里含有bus_num, 如果某个spi_master的bus_num跟它一样 * 则创建一个新的spi_device */ if (master->bus_num == bi->busnum) spi_new_device spi_alloc_device /* 记录bi信息, 比如片选，MODE，MAX HZ */ spi_add_device /* 根据名字找到spi_driver, 调用它的probe函数 */ spi_setup(spi); device_add /* 会绑定到一个spi_driver */ 2.2 数据收发过程 spi_write spi_message_init(&m); 初始化一个spi_message /* 一个不可打断的SPI传输过程: cs=0,传数据,cs=1 */ /* 一个spi_message由多个spi_transfer组成 */ spi_message_add_tail(&t, &m); /* spi_transfe是SPI上传输的单方向1个或多个字节 */ spi_sync(spi, &m); /* 启动传输并等待完成 */ 2.3 spi_driver如何调用spi_controller spi_sync __spi_sync(spi, message, 0); spi_async_locked __spi_async master->transfer(spi, message); wait_for_completion 3.实例：SPI OLED驱动 3.1 准备工作 sudo tar xjf arm-linux-gcc-4.3.2.tar.bz2 -C / export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/arm/4.3.2/bin tar xjf linux-3.4.2.tar.bz2 cd linux-3.4.2 patch -p1 < ../linux-3.4.2_camera_jz2440.patch cp config_ok .config make uImage sudo tar xjf fs_mini_mdev_new.tar.bz2 -C /work/nfs_root 3.2 写代码 a. 构造注册spi_board_info b. 构造注册spi_driver c. 检查代码，特别是spi_master: drivers\spi\spi-s3c24xx.c c.1 它注册了名为"s3c2410-spi"的platform_driver 需要有同名的platform_device 修改arch\arm\mach-s3c24xx\mach-smdk2440.c static struct platform_device *smdk2440_devices[] __initdata = { &s3c_device_ohci, &s3c_device_lcd, &s3c_device_wdt, &s3c_device_i2c0, &s3c_device_iis, + &s3c_device_spi0, + &s3c_device_spi1, }; c.2 给platform_dev添加platform_data arch\arm\plat-samsung\devs.c d. 编译安装驱动 d.1 配置内核使用主控驱动 spi-s3c24xx.c -> General setup [*] Prompt for development and/or incomplete code/drivers -> Device Drivers -> SPI support <*> Samsung S3C24XX series SPI make uImage cp arch/arm/boot/uImage /work/nfs_root uboot: set 'bootcmd nfs 30000000 192.168.1.124:/work/nfs_root/uImage ; bootm 30000000' set bootargs console=ttySAC0,115200 root=/dev/nfs nfsroot=192.168.1.124:/work/nfs_root/fs_mini_mdev_new ip=192.168.1.17 save boot 注意：spi_register_board_info没有被EXPORT_SYMBOL，所以： spi_info_jz2440.c只能被编进内核，而无法作为模块使用 cp spi_info_jz2440.c /work/system/linux-3.4.2/drivers/spi/ 修改drivers/spi/Makefile,添加这行： obj-$(CONFIG_SPI_S3C24XX) += spi_info_jz2440.o d.2 编译驱动 d.3 insmod e. 写测试程序 4.实例：SPI FLASH驱动（字符设备、块设备） 5.SPI控制器驱动 测试 a. 去掉内核自带的spi_master驱动 修改 drivers/spi/Makefile: #obj-$(CONFIG_SPI_S3C24XX) += spi-s3c24xx-hw.o #spi-s3c24xx-hw-y := spi-s3c24xx.o #spi-s3c24xx-hw-$(CONFIG_SPI_S3C24XX_FIQ) += spi-s3c24xx-fiq.o b. 编译spi_s3c2440.c c. insmod spi_s3c2440.ko insmod spi_oled_drv.ko insmod spi_flash_drv.ko /oled_test init /oled_test 0 0 100ask.taobao.com mkfs.vfat /dev/mtdblock4 mount -t vfat /dev/mtdblock4 /mnt export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/arm/4.3.2/bin http://www.cnblogs.com/liugf05/archive/2012/12/03/2800457.html struct spi_master *master; int (*setup)(struct spi_device *spi); int (*transfer)(struct spi_device *spi, struct spi_message *mesg); /* called on release() to free memory provided by spi_master */ void (*cleanup)(struct spi_device *spi); spi_bitbang setup_transfer txrx_bufs spi_bitbang_start spi_register_master boardinfo spi_register_driver spi_register_board_info spi_match_master_to_boardinfo spi_new_device(master, bi); spi_alloc_device export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/arm/4.3.2/bin set 'bootcmd nfs 30000000 192.168.1.124:/work/nfs_root/uImage ; bootm 30000000' set bootargs console=ttySAC0,115200 root=/dev/nfs nfsroot=192.168.1.124:/work/nfs_root/fs_mini_mdev_new ip=192.168.1.17 1. 配置内核 drivers\spi\spi-s3c24xx.c : platform_driver, "s3c2410-spi" arch\arm\plat-samsung\devs.c, "s3c2410-spi" 构造一个 s3c2410_spi_info ，实现 set_cs arch\arm\mach-s3c24xx\mach-smdk2440.c : 在static struct platform_device *smdk2440_devices[] __initdata = { 中加入： static struct platform_device *smdk2440_devices[] __initdata = { &s3c_device_spi0, &s3c_device_spi1, };