linux设备模型之input子系统
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摘要：
input子系统是kernel中比较简单的一个子系统，主要用来管理输入设备(触摸屏，键盘等等),个人感
觉可以作为driver的起点，输入设备不明思议，要提供输入信息，input子系统将这些信息当作事件，进行区分，实
时的上传！input中不是那么规矩，并没有抽象出来总线的概念(硬件上不存在)，而是用一个结构struct input_handle充当了总线
的结构，struct input_handle挂接了操作结构以及设备，input设备用struct input_dev结构来表示，操作函数用struct input_handler
来表示，注意这里input_handle和input_handler很相似，存在全局的input设备链表input_dev_list，用于连接所有input devices，
存在全局的input操作链表input_handler_list,用于挂接所有handler.
主要涉及目录：drivers/input
struct input_dev
一、相关数据结构
1.input device
struct input_dev {
const char *name; //名字
const char *phys; //物理地址
const char *uniq; //设备特殊标识码
struct input_id id; //设备id
unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)]; //设备属性相关位图
unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; //支持的事件
unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; //key,button位图
unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; //相对坐标
unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; //绝对坐标
unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)]; //杂项事件支持
unsigned long ledbit[BITS_TO_LONGS(LED_CNT)]; //led相关
unsigned long sndbit[BITS_TO_LONGS(SND_CNT)]; //音响效果相关
unsigned long ffbit[BITS_TO_LONGS(FF_CNT)];
unsigned long swbit[BITS_TO_LONGS(SW_CNT)];
unsigned int hint_events_per_packet;
unsigned int keycodemax; //键码表大小
unsigned int keycodesize;
void *keycode; //按键扫描码
int (*setkeycode)(struct input_dev *dev, //老式扫描方法
const struct input_keymap_entry *ke,
unsigned int *old_keycode);
int (*getkeycode)(struct input_dev *dev,
struct input_keymap_entry *ke);
struct ff_device *ff;
unsigned int repeat_key;
struct timer_list timer; //定时器
int rep[REP_CNT];
struct input_mt_slot *mt;
int mtsize;
int slot;
int trkid;
struct input_absinfo *absinfo;
unsigned long key[BITS_TO_LONGS(KEY_CNT)];
unsigned long led[BITS_TO_LONGS(LED_CNT)];
unsigned long snd[BITS_TO_LONGS(SND_CNT)];
unsigned long sw[BITS_TO_LONGS(SW_CNT)];
int (*open)(struct input_dev *dev); //open回调函数
void (*close)(struct input_dev *dev);
int (*flush)(struct input_dev *dev, struct file *file);
int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);
struct input_handle __rcu *grab;
spinlock_t event_lock;
struct mutex mutex;
unsigned int users;
bool going_away;
bool sync;
struct device dev; //devices 模型
struct list_head h_list; //连接相应的handle
struct list_head node; //挂接到全局input_dev_list
};2.操作函数结构input_handler
struct input_handler {
void *private; //私有属性结构
void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
bool (*filter)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
bool (*match)(struct input_handler *handler, struct input_dev *dev);
int (*connect)(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id);
void (*disconnect)(struct input_handle *handle);
void (*start)(struct input_handle *handle);
const struct file_operations *fops;
int minor;
const char *name; //名字
const struct input_device_id *id_table; //支持的devices,id表
struct list_head h_list; //用于连接到对应的handle的
struct list_head node; //用于连接到全局的input_handler_list链表
};3.bus的充当者总体管理结构
struct input_handle {
void *private; //私有数据结构
int open; //open计数
const char *name; //名字
struct input_dev *dev; //连接设备
struct input_handler *handler; //连接driver的操作函数
struct list_head d_node; //设备挂接点
struct list_head h_node; //handle挂接点
};
二、相关的操作函数
1.关心一下核心文件input.c,input子系统的初始化:
static int __init input_init(void)
{
int err;
err = class_register(&input_class); //注册input类，出现在sys/class下
if (err) {
pr_err("unable to register input_dev class\n");
return err;
}
err = input_proc_init(); //在proc下添加相关信息(bus/input)
if (err)
goto fail1;
err = register_chrdev(INPUT_MAJOR, "input", &input_fops); //注册成字符设备，设备号13
if (err) {
pr_err("unable to register char major %d", INPUT_MAJOR);
goto fail2;
}
return 0;
fail2: input_proc_exit();
fail1: class_unregister(&input_class);
return err;
}
貌似戛然而止了，^.^!,
2.向input子系统添加设备的函数,
int input_register_device(struct input_dev *dev)
{
static atomic_t input_no = ATOMIC_INIT(0);
struct input_handler *handler;
const char *path;
int error;
/* Every input device generates EV_SYN/SYN_REPORT events. */
__set_bit(EV_SYN, dev->evbit);
/* 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);
if (!dev->hint_events_per_packet)
dev->hint_events_per_packet =
input_estimate_events_per_packet(dev);
/*
* 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.
*/
init_timer(&dev->timer);
if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
dev->timer.data = (long) dev;
dev->timer.function = input_repeat_key;
dev->rep[REP_DELAY] = 250;
dev->rep[REP_PERIOD] = 33;
}
if (!dev->getkeycode)
dev->getkeycode = input_default_getkeycode; //如果没有设置，设置成默认值
if (!dev->setkeycode)
dev->setkeycode = input_default_setkeycode;
dev_set_name(&dev->dev, "input%ld", //name
(unsigned long) atomic_inc_return(&input_no) - 1);
error = device_add(&dev->dev); //标准设备的加入，这个，，加哪去了，没bus的野设备？？
if (error) //直接扔到系统全局总设备链表了
return error;
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) {
device_del(&dev->dev);
return error;
}
list_add_tail(&dev->node, &input_dev_list); //加入全局input device链表
list_for_each_entry(handler, &input_handler_list, node) //遍历handler链表，匹配合适的handler
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
mutex_unlock(&input_mutex);
return 0;
}继续跟一下input_attach_handler函数,
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); //具体的匹配函数
if (!id)
return -ENODEV;
error = handler->connect(handler, dev, id); //匹配后调用connect函数
if (error && error != -ENODEV)
pr_err("failed to attach handler %s to device %s, error: %d\n",
handler->name, kobject_name(&dev->dev.kobj), error);
return error;
}还有个函数
static const struct input_device_id *input_match_device(struct input_handler *handler,
struct input_dev *dev)
{
const struct input_device_id *id;
int i;
for (id = handler->id_table; id->flags || id->driver_info; id++) {
if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
if (id->bustype != dev->id.bustype)
continue;
if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
if (id->vendor != dev->id.vendor)
continue;
if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
if (id->product != dev->id.product)
continue;
if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
if (id->version != dev->id.version)
continue;
MATCH_BIT(evbit, EV_MAX);
MATCH_BIT(keybit, KEY_MAX);
MATCH_BIT(relbit, REL_MAX);
MATCH_BIT(absbit, ABS_MAX);
MATCH_BIT(mscbit, MSC_MAX);
MATCH_BIT(ledbit, LED_MAX);
MATCH_BIT(sndbit, SND_MAX);
MATCH_BIT(ffbit, FF_MAX);
MATCH_BIT(swbit, SW_MAX);
if (!handler->match || handler->match(handler, dev)) //不光是调用match函数，上面的匹配也很严格，厂商
return id; //版本一个也不能少
}
return NULL;
}
3.handler的注册
同样handler也要有注册的
int input_register_handler(struct input_handler *handler)
{
struct input_dev *dev;
int retval;
retval = mutex_lock_interruptible(&input_mutex);
if (retval)
return retval;
INIT_LIST_HEAD(&handler->h_list);
if (handler->fops != NULL) {
if (input_table[handler->minor >> 5]) {
retval = -EBUSY;
goto out;
}
input_table[handler->minor >> 5] = handler;
}
list_add_tail(&handler->node, &input_handler_list); //加入全局handler链表
list_for_each_entry(dev, &input_dev_list, node) //遍历devices链表，匹配
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
out:
mutex_unlock(&input_mutex);
return retval;
}
三、input deivce实例
这个东东还是找个例子看起来比较方便,
翻一翻touchscreen下s3c2410_ts.c,
直接进入主题看probe
static int __devinit s3c2410ts_probe(struct platform_device *pdev) { struct s3c2410_ts_mach_info *info; struct device *dev = &pdev->dev; struct input_dev *input_dev; struct resource *res; int ret = -EINVAL; /* Initialise input stuff */ memset(&ts, 0, sizeof(struct s3c2410ts)); ts.dev = dev; info = pdev->dev.platform_data; if (!info) { dev_err(dev, "no platform data, cannot attach\n"); return -EINVAL; } dev_dbg(dev, "initialising touchscreen\n"); ts.clock = clk_get(dev, "adc"); //申请clock if (IS_ERR(ts.clock)) { dev_err(dev, "cannot get adc clock source\n"); return -ENOENT; } clk_enable(ts.clock); //使能clock dev_dbg(dev, "got and enabled clocks\n"); ts.irq_tc = ret = platform_get_irq(pdev, 0); //中断号 if (ret < 0) { dev_err(dev, "no resource for interrupt\n"); goto err_clk; } res = platform_get_resource(pdev, IORESOURCE_MEM, 0); //相关寄存器地址 if (!res) { dev_err(dev, "no resource for registers\n"); ret = -ENOENT; goto err_clk; } ts.io = ioremap(res->start, resource_size(res)); //进行映射 if (ts.io == NULL) { dev_err(dev, "cannot map registers\n"); ret = -ENOMEM; goto err_clk; } /* inititalise the gpio */ if (info->cfg_gpio) info->cfg_gpio(to_platform_device(ts.dev)); //相关gpio配置 ts.client = s3c_adc_register(pdev, s3c24xx_ts_select, //注意这里adc核心相关，select会启动timer上报adc事件 s3c24xx_ts_conversion, 1); if (IS_ERR(ts.client)) { dev_err(dev, "failed to register adc client\n"); ret = PTR_ERR(ts.client); goto err_iomap; } /* Initialise registers */ if ((info->delay & 0xffff) > 0) writel(info->delay & 0xffff, ts.io + S3C2410_ADCDLY); writel(WAIT4INT | INT_DOWN, ts.io + S3C2410_ADCTSC); input_dev = input_allocate_device(); //这里重点，分配了一个input device设备 if (!input_dev) { dev_err(dev, "Unable to allocate the input device !!\n"); ret = -ENOMEM; goto err_iomap; } ts.input = input_dev; ts.input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); ts.input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); input_set_abs_params(ts.input, ABS_X, 0, 0x3FF, 0, 0); input_set_abs_params(ts.input, ABS_Y, 0, 0x3FF, 0, 0); ts.input->name = "S3C24XX TouchScreen"; ts.input->id.bustype = BUS_HOST; ts.input->id.vendor = 0xDEAD; ts.input->id.product = 0xBEEF; ts.input->id.version = 0x0102; ts.shift = info->oversampling_shift; ts.features = platform_get_device_id(pdev)->driver_data; ret = request_irq(ts.irq_tc, stylus_irq, 0, //申请中断，input设备大多都是使用中断的，pen down up事件 "s3c2410_ts_pen", ts.input); if (ret) { dev_err(dev, "cannot get TC interrupt\n"); goto err_inputdev; } dev_info(dev, "driver attached, registering input device\n"); /* All went ok, so register to the input system */ ret = input_register_device(ts.input); //这里注册input device if (ret < 0) { dev_err(dev, "failed to register input device\n"); ret = -EIO; goto err_tcirq; } return 0; err_tcirq: free_irq(ts.irq_tc, ts.input); err_inputdev: input_free_device(ts.input); err_iomap: iounmap(ts.io); err_clk: del_timer_sync(&touch_timer); clk_put(ts.clock); return ret; }
看一下 input_allocate_device函数，struct input_dev *input_allocate_device(void) { struct input_dev *dev; dev = kzalloc(sizeof(struct input_dev), GFP_KERNEL); if (dev) { dev->dev.type = &input_dev_type; //初始化成input类型 dev->dev.class = &input_class; device_initialize(&dev->dev); mutex_init(&dev->mutex); spin_lock_init(&dev->event_lock); INIT_LIST_HEAD(&dev->h_list); INIT_LIST_HEAD(&dev->node); __module_get(THIS_MODULE); } return dev; }irq用于判断pen down up，启动adc上报坐标事件.
未完待续....
Thanks