4.11.2. 输入核心层
输入核心层，是input子系统实现的核心。对上(事件驱动层)提供事件注册接口等，对下(设备驱动层)提供设备注册接口，输入信息反馈接口
4.11.2.1. 设备驱动层接口
申请设备描述符结构体变量，同时初始化一些通用性数据结构
/**
* input_allocate_device - allocate memory for new input device
*
* Returns prepared struct input_dev or %NULL.
*
* NOTE: Use input_free_device() to free devices that have not been
* registered; input_unregister_device() should be used for already
* registered devices.
*/
struct input_dev *input_allocate_device(void)
{
static atomic_t input_no = ATOMIC_INIT(-1);
struct input_dev *dev;
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (dev) {
dev->dev.type = &input_dev_type; //绑定设备信息
dev->dev.class = &input_class; //绑定在sysfs所属的类
device_initialize(&dev->dev); //设备初始化
mutex_init(&dev->mutex);
spin_lock_init(&dev->event_lock);
timer_setup(&dev->timer, NULL, 0); //内核定时器初始化
INIT_LIST_HEAD(&dev->h_list);
INIT_LIST_HEAD(&dev->node);
dev_set_name(&dev->dev, "input%lu",
(unsigned long)atomic_inc_return(&input_no));
__module_get(THIS_MODULE);
}
return dev;
}
设置dev设备的能力，只有注册前设置它的能力，将来设备注册后，发送的信息才能上报。注:该函数每次只能设置一个能力
根据type类型设置code到相应的typebit
/**
* input_set_capability - mark device as capable of a certain event
* @dev: device that is capable of emitting or accepting event
* @type: type of the event (EV_KEY, EV_REL, etc...)
* @code: event code
*
* In addition to setting up corresponding bit in appropriate capability
* bitmap the function also adjusts dev->evbit.
*/
void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code)
{
switch (type) {
case EV_KEY:
__set_bit(code, dev->keybit);
break;
case EV_REL:
__set_bit(code, dev->relbit);
break;
case EV_ABS:
input_alloc_absinfo(dev);
if (!dev->absinfo)
return;
__set_bit(code, dev->absbit);
break;
case EV_MSC:
__set_bit(code, dev->mscbit);
break;
case EV_SW:
__set_bit(code, dev->swbit);
break;
case EV_LED:
__set_bit(code, dev->ledbit);
break;
case EV_SND:
__set_bit(code, dev->sndbit);
break;
case EV_FF:
__set_bit(code, dev->ffbit);
break;
case EV_PWR:
/* do nothing */
break;
default:
pr_err("%s: unknown type %u (code %u)\n", __func__, type, code);
dump_stack();
return;
}
__set_bit(type, dev->evbit);
}
具体设备注册(需要前两步申请空间和填充能力才能注册)
int input_register_device(struct input_dev *dev)
{
struct input_devres *devres = NULL;
struct input_handler *handler;
unsigned int packet_size;
const char *path;
int error;
if (test_bit(EV_ABS, dev->evbit) && !dev->absinfo) {
dev_err(&dev->dev,
"Absolute device without dev->absinfo, refusing to register\n");
return -EINVAL;
}
if (dev->devres_managed) {
devres = devres_alloc(devm_input_device_unregister,
sizeof(*devres), GFP_KERNEL);
if (!devres)
return -ENOMEM;
devres->input = dev;
}
/* Every input device generates EV_SYN/SYN_REPORT events. */
__set_bit(EV_SYN, dev->evbit); //通用的同步包
/* KEY_RESERVED is not supposed to be transmitted to userspace. */
__clear_bit(KEY_RESERVED, dev->keybit);
/* Make sure that bitmasks not mentioned in dev->evbit are clean. */
input_cleanse_bitmasks(dev);
packet_size = input_estimate_events_per_packet(dev);
if (dev->hint_events_per_packet < packet_size)
dev->hint_events_per_packet = packet_size;
dev->max_vals = dev->hint_events_per_packet + 2;
dev->vals = kcalloc(dev->max_vals, sizeof(*dev->vals), GFP_KERNEL);
if (!dev->vals) {
error = -ENOMEM;
goto err_devres_free;
}
/*
* If delay and period are pre-set by the driver, then autorepeating
* is handled by the driver itself and we don't do it in input.c.
*/
if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD])
input_enable_softrepeat(dev, 250, 33);
if (!dev->getkeycode)
dev->getkeycode = input_default_getkeycode;
if (!dev->setkeycode)
dev->setkeycode = input_default_setkeycode;
if (dev->poller)
input_dev_poller_finalize(dev->poller);
error = device_add(&dev->dev);
if (error)
goto err_free_vals;
path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
pr_info("%s as %s\n",
dev->name ? dev->name : "Unspecified device",
path ? path : "N/A");
kfree(path);
error = mutex_lock_interruptible(&input_mutex);
if (error)
goto err_device_del;
list_add_tail(&dev->node, &input_dev_list);
list_for_each_entry(handler, &input_handler_list, node)
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
mutex_unlock(&input_mutex);
if (dev->devres_managed) {
dev_dbg(dev->dev.parent, "%s: registering %s with devres.\n",
__func__, dev_name(&dev->dev));
devres_add(dev->dev.parent, devres);
}
return 0;
err_device_del:
device_del(&dev->dev);
err_free_vals:
kfree(dev->vals);
dev->vals = NULL;
err_devres_free:
devres_free(devres);
return error;
}
EXPORT_SYMBOL(input_register_device);
handler和dev做匹配，如果匹配上则把两者绑定
static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
{
const struct input_device_id *id;
int error;
id = input_match_device(handler, dev); /* 匹配handler和dev */
if (!id)
return -ENODEV;
error = handler->connect(handler, dev, id); /* 做具体的绑定handler和dev工作，由具体的事驱动层实现 */
if (error && error != -ENODEV)
printk(KERN_ERR
"input: failed to attach handler %s to device %s, "
"error: %d\n",
handler->name, kobject_name(&dev->dev.kobj), error);
return error;
}
此函数在注册dev和handler的时候都会调用
匹配handler和dev
每一个事件驱动层在实现的时候都要实现一个struct input_device_id的表，用来表示该事件驱动可以支持的设备
struct input_device_id数据结构如下
struct input_device_id {
kernel_ulong_t flags; //flag表明下面四个要不要匹配
__u16 bustype;
__u16 vendor;
__u16 product;
__u16 version;
kernel_ulong_t evbit[INPUT_DEVICE_ID_EV_MAX / BITS_PER_LONG + 1];
kernel_ulong_t keybit[INPUT_DEVICE_ID_KEY_MAX / BITS_PER_LONG + 1];
kernel_ulong_t relbit[INPUT_DEVICE_ID_REL_MAX / BITS_PER_LONG + 1];
kernel_ulong_t absbit[INPUT_DEVICE_ID_ABS_MAX / BITS_PER_LONG + 1];
kernel_ulong_t mscbit[INPUT_DEVICE_ID_MSC_MAX / BITS_PER_LONG + 1];
kernel_ulong_t ledbit[INPUT_DEVICE_ID_LED_MAX / BITS_PER_LONG + 1];
kernel_ulong_t sndbit[INPUT_DEVICE_ID_SND_MAX / BITS_PER_LONG + 1];
kernel_ulong_t ffbit[INPUT_DEVICE_ID_FF_MAX / BITS_PER_LONG + 1];
kernel_ulong_t swbit[INPUT_DEVICE_ID_SW_MAX / BITS_PER_LONG + 1];
kernel_ulong_t propbit[INPUT_DEVICE_ID_PROP_MAX / BITS_PER_LONG + 1];
kernel_ulong_t driver_info;
};
static const struct input_device_id *input_match_device(struct input_handler *handler,
struct input_dev *dev)
{
const struct input_device_id *id;
for (id = handler->id_table; id->flags || id->driver_info; id++) {
if (input_match_device_id(dev, id) &&
(!handler->match || handler->match(handler, dev))) {
return id;
}
}
return NULL;
}
bool input_match_device_id(const struct input_dev *dev,
const struct input_device_id *id)
{
if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
if (id->bustype != dev->id.bustype)
return false;
if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
if (id->vendor != dev->id.vendor)
return false;
if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
if (id->product != dev->id.product)
return false;
if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
if (id->version != dev->id.version)
return false;
if (!bitmap_subset(id->evbit, dev->evbit, EV_MAX) ||
!bitmap_subset(id->keybit, dev->keybit, KEY_MAX) ||
!bitmap_subset(id->relbit, dev->relbit, REL_MAX) ||
!bitmap_subset(id->absbit, dev->absbit, ABS_MAX) ||
!bitmap_subset(id->mscbit, dev->mscbit, MSC_MAX) ||
!bitmap_subset(id->ledbit, dev->ledbit, LED_MAX) ||
!bitmap_subset(id->sndbit, dev->sndbit, SND_MAX) ||
!bitmap_subset(id->ffbit, dev->ffbit, FF_MAX) ||
!bitmap_subset(id->swbit, dev->swbit, SW_MAX) ||
!bitmap_subset(id->propbit, dev->propbit, INPUT_PROP_MAX)) {
return false;
}
return true;
}
4.11.2.2. 事件驱动层
handler注册
int input_register_handler(struct input_handler *handler)
{
struct input_dev *dev;
int error;
error = mutex_lock_interruptible(&input_mutex);
if (error)
return error;
INIT_LIST_HEAD(&handler->h_list); //初始化链表
list_add_tail(&handler->node, &input_handler_list); //加入到input_handler_list链表中
list_for_each_entry(dev, &input_dev_list, node)
input_attach_handler(dev, handler); //dev与handler匹配
input_wakeup_procfs_readers(); //更新proc系统
mutex_unlock(&input_mutex);
return 0;
}
EXPORT_SYMBOL(input_register_handler);
handle的注册(其实就是把handler和dev的链表加入到handle的数据中)
int input_register_handle(struct input_handle *handle)
{
struct input_handler *handler = handle->handler;
struct input_dev *dev = handle->dev;
int error;
/*
* We take dev->mutex here to prevent race with
* input_release_device().
*/
error = mutex_lock_interruptible(&dev->mutex);
if (error)
return error;
/*
* Filters go to the head of the list, normal handlers
* to the tail.
*/
if (handler->filter)
list_add_rcu(&handle->d_node, &dev->h_list);
else
list_add_tail_rcu(&handle->d_node, &dev->h_list);
mutex_unlock(&dev->mutex);
/*
* Since we are supposed to be called from ->connect()
* which is mutually exclusive with ->disconnect()
* we can't be racing with input_unregister_handle()
* and so separate lock is not needed here.
*/
list_add_tail_rcu(&handle->h_node, &handler->h_list);
if (handler->start)
handler->start(handle);
return 0;
}