// drivers/spi/spi.c
2772 postcore_initcall(spi_init); // spi_init
2733 static int __init spi_init(void)
2734 {
2735 int status;
2736
2737 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
2738 if (!buf) {
2739 status = -ENOMEM;
2740 goto err0;
2741 }
2742
2743 status = bus_register(&spi_bus_type);
2744 if (status < 0)
2745 goto err1;
2746
2747 status = class_register(&spi_master_class);
2748 if (status < 0)
2749 goto err2;
2750
2751 if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2752 WARN_ON(of_reconfig_notifier_register(&spi_of_notifier)); // 这里要注册 主机和从机
2753
2754 return 0;
2755
2756 err2:
2757 bus_unregister(&spi_bus_type);
2758 err1:
2759 kfree(buf);
2760 buf &