platform_driver_register与of_register_platform_driver分析(二）

接着上篇
/**
 * platform_driver_register - register a driver for platform-level devices
 * @drv: platform driver structure
 */
int platform_driver_register(struct platform_driver *drv)
{
    drv->driver.bus = &platform_bus_type;
    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);
}
EXPORT_SYMBOL_GPL(platform_driver_register);
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struct bus_type {
    const char        *name;
    struct bus_attribute    *bus_attrs;
    struct device_attribute    *dev_attrs;
    struct driver_attribute    *drv_attrs;

    int (*match)(struct device *dev, struct device_driver *drv);
    int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
    int (*probe)(struct device *dev);
    int (*remove)(struct device *dev);
    void (*shutdown)(struct device *dev);

    int (*suspend)(struct device *dev, pm_message_t state);
    int (*resume)(struct device *dev);

    const struct dev_pm_ops *pm;

    struct bus_type_private *p;
};

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

struct platform_device {
    const char    * name;
    int        id;
    struct device    dev;
    u32        num_resources;
    struct resource    * resource;

    const struct platform_device_id    *id_entry;

    /* arch specific additions */
    struct pdev_archdata    archdata;
};

/**
 * platform_match - bind platform device to platform driver.
 * @dev: device.
 * @drv: driver.
 *
 * Platform device IDs are assumed to be encoded like this:
 * "<name><instance>", where <name> is a short description of the type of
 * device, like "pci" or "floppy", and <instance> is the enumerated
 * instance of the device, like '0' or '42'.  Driver IDs are simply
 * "<name>".  So, extract the <name> from the platform_device structure,
 * and compare it against the name of the driver. Return whether they match
 * or not.
 */
static int platform_match(struct device *dev, struct device_driver *drv)
{
    struct platform_device *pdev = to_platform_device(dev);//获取dev结构体首地址
    struct platform_driver *pdrv = to_platform_driver(drv);//同上

    /* 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);
}
platform_match_id()代码如下 id_table中匹配名字，成功返回
static const struct platform_device_id *platform_match_id(
            const struct platform_device_id *id,
            struct platform_device *pdev)
{
    while (id->name[0]) {
        if (strcmp(pdev->name, id->name) == 0) {
            pdev->id_entry = id;
            return id;
        }
        id++;
    }
    return NULL;
}
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
static int platform_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    struct platform_device    *pdev = to_platform_device(dev);

    add_uevent_var(env, "MODALIAS=%s%s", PLATFORM_MODULE_PREFIX,
        (pdev->id_entry) ? pdev->id_entry->name : pdev->name);
    return 0;
}
和powerpc类似，都调用了add_uevent_var
/**
 * add_uevent_var - add key value string to the environment buffer
 * @env: environment buffer structure
 * @format: printf format for the key=value pair
 *
 * Returns 0 if environment variable was added successfully or -ENOMEM
 * if no space was available.
 */
int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
{
    va_list args;
    int len;

    if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
        WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
        return -ENOMEM;
    }

    va_start(args, format);
    len = vsnprintf(&env->buf[env->buflen],
            sizeof(env->buf) - env->buflen,
            format, args);
    va_end(args);

    if (len >= (sizeof(env->buf) - env->buflen)) {
        WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
        return -ENOMEM;
    }

    env->envp[env->envp_idx++] = &env->buf[env->buflen];
    env->buflen += len + 1;
    return 0;
}