int platform_driver_register(struct platform_driver *drv)
{
    drv->driver.bus = &platform_bus_type;/*关联总线*/
    /*关联driver的设备方法*/
    if (drv->probe)
        drv->driver.probe = platform_drv_probe;
    if (drv->remove)
        drv->driver.remove = platform_drv_remove;
    if (drv->shutdown)
        drv->driver.shutdown = platform_drv_shutdown;

    return driver_register(&drv->driver);/*注册驱动*/
}

/******************************************************************************/
struct platform_driver {
    int (*probe)(struct platform_device *);/*匹配到设备后调用，下面分析内核代码怎么调用的*/
    int (*remove)(struct platform_device *);
    void (*shutdown)(struct platform_device *);
    int (*suspend)(struct platform_device *, pm_message_t state);
    int (*resume)(struct platform_device *);
    struct device_driver driver;
    const struct platform_device_id *id_table;
};

struct bus_type platform_bus_type = {
    .name        = "platform",
    .dev_attrs    = platform_dev_attrs,
    .match        = platform_match,
    .uevent        = platform_uevent,
    .pm        = &platform_dev_pm_ops,
};
/********************************************************************************/

int driver_register(struct device_driver *drv)
{
    int ret;
    struct device_driver *other;

    BUG_ON(!drv->bus->p);

    if ((drv->bus->probe && drv->probe) ||
        (drv->bus->remove && drv->remove) ||
        (drv->bus->shutdown && drv->shutdown))
        printk(KERN_WARNING "Driver ‘%s‘ needs updating - please use "
            "bus_type methods\n", drv->name);

    other = driver_find(drv->name, drv->bus);
    if (other) {
        put_driver(other);
        printk(KERN_ERR "Error: Driver ‘%s‘ is already registered, "
            "aborting...\n", drv->name);
        return -EBUSY;
    }

    ret = bus_add_driver(drv);
    if (ret)
        return ret;
    ret = driver_add_groups(drv, drv->groups);
    if (ret)
        bus_remove_driver(drv);
    return ret;
}

int bus_add_driver(struct device_driver *drv)
{
    struct bus_type *bus;
    struct driver_private *priv;
    int error = 0;

    bus = bus_get(drv->bus);
    if (!bus)
        return -EINVAL;

    pr_debug("bus: ‘%s‘: add driver %s\n", bus->name, drv->name);

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (!priv) {
        error = -ENOMEM;
        goto out_put_bus;
    }
    klist_init(&priv->klist_devices, NULL, NULL);
    priv->driver = drv;
    drv->p = priv;
    priv->kobj.kset = bus->p->drivers_kset;
    error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
                     "%s", drv->name);
    if (error)
        goto out_unregister;

    if (drv->bus->p->drivers_autoprobe) {
        error = driver_attach(drv);
        if (error)
            goto out_unregister;
    }
    klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
    module_add_driver(drv->owner, drv);

    error = driver_create_file(drv, &driver_attr_uevent);
    if (error) {
        printk(KERN_ERR "%s: uevent attr (%s) failed\n",
            __func__, drv->name);
    }
    error = driver_add_attrs(bus, drv);
    if (error) {
        /* How the hell do we get out of this pickle? Give up */
        printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
            __func__, drv->name);
    }

    if (!drv->suppress_bind_attrs) {
        error = add_bind_files(drv);
        if (error) {
            /* Ditto */
            printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
                __func__, drv->name);
        }
    }

    kobject_uevent(&priv->kobj, KOBJ_ADD);
    return 0;

out_unregister:
    kobject_put(&priv->kobj);
    kfree(drv->p);
    drv->p = NULL;
out_put_bus:
    bus_put(bus);
    return error;
}

int driver_attach(struct device_driver *drv)
{
    /*对总线上的每一个设备都调用__driver_attach*/
    return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
}

static int __driver_attach(struct device *dev, void *data)
{
    struct device_driver *drv = data;

    /*
     * Lock device and try to bind to it. We drop the error
     * here and always return 0, because we need to keep trying
     * to bind to devices and some drivers will return an error
     * simply if it didn‘t support the device.
     *
     * driver_probe_device() will spit a warning if there
     * is an error.
     */

    if (!driver_match_device(drv, dev))
        return 0;

    if (dev->parent)    /* Needed for USB */
        device_lock(dev->parent);
    device_lock(dev);
    if (!dev->driver)
        driver_probe_device(drv, dev);
    device_unlock(dev);
    if (dev->parent)
        device_unlock(dev->parent);

    return 0;
}

static inline int driver_match_device(struct device_driver *drv,
                      struct device *dev)
{
    /*调用总线的match去匹配设备和驱动*/
    return drv->bus->match ? drv->bus->match(dev, drv) : 1;
}

int driver_probe_device(struct device_driver *drv, struct device *dev)
{
    int ret = 0;

    if (!device_is_registered(dev))
        return -ENODEV;

    pr_debug("bus: ‘%s‘: %s: matched device %s with driver %s\n",
         drv->bus->name, __func__, dev_name(dev), drv->name);

    pm_runtime_get_noresume(dev);
    pm_runtime_barrier(dev);
    ret = really_probe(dev, drv);
    pm_runtime_put_sync(dev);

    return ret;
}
static int really_probe(struct device *dev, struct device_driver *drv)
{
    int ret = 0;

    atomic_inc(&probe_count);
    pr_debug("bus: ‘%s‘: %s: probing driver %s with device %s\n",
         drv->bus->name, __func__, drv->name, dev_name(dev));
    WARN_ON(!list_empty(&dev->devres_head));

    dev->driver = drv;
    if (driver_sysfs_add(dev)) {
        printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
            __func__, dev_name(dev));
        goto probe_failed;
    }
/**********************************************************************************/
    if (dev->bus->probe) {/*首先看总线有没有probe函数，若有则调用，而平台总线没有probe*/
        ret = dev->bus->probe(dev);
        if (ret)
            goto probe_failed;
    } else if (drv->probe) {/*然后看驱动有没有probe函数，若有则调用，*/
        ret = drv->probe(dev);
        if (ret)
            goto probe_failed;
    }
/************************************************************************************/

    driver_bound(dev);
    ret = 1;
    pr_debug("bus: ‘%s‘: %s: bound device %s to driver %s\n",
         drv->bus->name, __func__, dev_name(dev), drv->name);
    goto done;

probe_failed:
    devres_release_all(dev);
    driver_sysfs_remove(dev);
    dev->driver = NULL;

    if (ret != -ENODEV && ret != -ENXIO) {
        /* driver matched but the probe failed */
        printk(KERN_WARNING
               "%s: probe of %s failed with error %d\n",
               drv->name, dev_name(dev), ret);
    }
    /*
     * Ignore errors returned by ->probe so that the next driver can try
     * its luck.
     */
    ret = 0;
done:
    atomic_dec(&probe_count);
    wake_up(&probe_waitqueue);
    return ret;
}


/*平台总线的match逻辑*/
static int platform_match(struct device *dev, struct device_driver *drv)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct platform_driver *pdrv = to_platform_driver(drv);

    /* match against the id table first */
    if (pdrv->id_table)
        return platform_match_id(pdrv->id_table, pdev) != NULL;

    /* fall-back to driver name match */
    return (strcmp(pdev->name, drv->name) == 0);/*驱动名字与设备名字要匹配*/
}