static ssize_t mahimahi_virtual_keys_show(struct kobject *kobj,
			       struct kobj_attribute *attr, char *buf)
{
	if (system_rev > 2) {
		/* center: x: back: 55, menu: 172, home: 298, search 412, y: 835 */
		return sprintf(buf,
			__stringify(EV_KEY) ":" __stringify(KEY_BACK)  ":55:835:90:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_MENU)   ":172:835:125:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_HOME)   ":298:835:115:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_SEARCH) ":412:835:95:55"
		   "\n");
	} else {
		/* center: x: home: 55, menu: 185, back: 305, search 425, y: 835 */
		return sprintf(buf,
			__stringify(EV_KEY) ":" __stringify(KEY_HOME)  ":55:835:70:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_MENU)   ":185:835:100:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_BACK)   ":305:835:70:55"
		   ":" __stringify(EV_KEY) ":" __stringify(KEY_SEARCH) ":425:835:70:55"
		   "\n");
	}
}
 
static struct kobj_attribute mahimahi_virtual_keys_attr = {
	.attr = {
		.name = "virtualkeys.synaptics-rmi-touchscreen",
		.mode = S_IRUGO,
	},
	.show = &mahimahi_virtual_keys_show,
};
 
static struct attribute *mahimahi_properties_attrs[] = {
	&mahimahi_virtual_keys_attr.attr,
	NULL
};
 
static struct attribute_group mahimahi_properties_attr_group = {
	.attrs = mahimahi_properties_attrs,
};
 
struct kobject *properties_kobj;
 
properties_kobj = kobject_create_and_add("board_properties", NULL);
if (properties_kobj)
	ret = sysfs_create_group(properties_kobj,
					 &mahimahi_properties_attr_group);
if (!properties_kobj || ret)
	pr_err("failed to create board_properties\n");

/*这是虚拟按键的类里面包括了VirtualKey所用到的成员变量和按键定位方法*/
    static class VirtualKey {
        int scancode;
        int centerx;
        int centery;
        int width;
        int height;
 
        int hitLeft;
        int hitTop;
        int hitRight;
        int hitBottom;
 
        InputDevice lastDevice;
        int lastKeycode;
 
        boolean checkHit(int x, int y) {
            return (x >= hitLeft && x <= hitRight                     && y >= hitTop && y <= hitBottom);
        }
 
        void computeHitRect(InputDevice dev, int dw, int dh) {
            if (dev == lastDevice) {
                return;
            }
            if (DEBUG_VIRTUAL_KEYS) Log.v(TAG, "computeHitRect for " + scancode
                    + ": dev=" + dev + " absX=" + dev.absX + " absY=" + dev.absY);
 
            lastDevice = dev;
 
            int minx = dev.absX.minValue;
            int maxx = dev.absX.maxValue;
 
            int halfw = width/2;
            int left = centerx - halfw;
            int right = centerx + halfw;
            hitLeft = minx + ((left*maxx-minx)/dw);
            hitRight = minx + ((right*maxx-minx)/dw);
 
            int miny = dev.absY.minValue;
            int maxy = dev.absY.maxValue;
 
            int halfh = height/2;
            int top = centery - halfh;
            int bottom = centery + halfh;
            hitTop = miny + ((top*maxy-miny)/dh);
            hitBottom = miny + ((bottom*maxy-miny)/dh);
        }
    }
/*以下就是与底层接口的函数，如果这个函数和底层接口正常，基本上虚拟按键就能够ok*/
    private void readVirtualKeys(String deviceName) {
        try {
            FileInputStream fis = new FileInputStream(
                    "/sys/board_properties/virtualkeys." + deviceName);
/*这里就是读取kernel给出信息的地方，也就是地层与上层接口的地方，所以整个实现的重点就是这里*/
            InputStreamReader isr = new InputStreamReader(fis);
            BufferedReader br = new BufferedReader(isr, 2048);
            String str = br.readLine();
            if (str != null) {
                String[] it = str.split(":");
                if (DEBUG_VIRTUAL_KEYS) Log.v(TAG, "***** VIRTUAL KEYS: " + it);
                final int N = it.length-6;
                for (int i=0; i<=N; i+=6) {
                    if (!"0x01".equals(it[i])) {
                        Log.w(TAG, "Unknown virtual key type at elem #" + i
                                + ": " + it[i]);
                        continue;
                    }
                    try {
                        VirtualKey sb = new VirtualKey();
                        sb.scancode = Integer.parseInt(it[i+1]);
                        sb.centerx = Integer.parseInt(it[i+2]);
                        sb.centery = Integer.parseInt(it[i+3]);
                        sb.width = Integer.parseInt(it[i+4]);
                        sb.height = Integer.parseInt(it[i+5]);
                        if (DEBUG_VIRTUAL_KEYS) Log.v(TAG, "Virtual key "
                                + sb.scancode + ": center=" + sb.centerx + ","
                                + sb.centery + " size=" + sb.width + "x"
                                + sb.height);
                        mVirtualKeys.add(sb);
                    } catch (NumberFormatException e) {
                        Log.w(TAG, "Bad number at region " + i + " in: "
                                + str, e);
                    }
                }
            }
            br.close();
        } catch (FileNotFoundException e) {
            Log.i(TAG, "No virtual keys found");
        } catch (IOException e) {
            Log.w(TAG, "Error reading virtual keys", e);
        }
    }

struct hero_axis_info {
        struct gpio_event_axis_info info; /*gpio_event_axis结构的信息*/
        uint16_t in_state;/*记录输入的高低电平信号*/
        uint16_t out_state;/*记录输出的高低电平信号*/
        uint16_t temp_state;/*临时存储高低电平*/
        uint16_t threshold;/*门限值，超过这个值上报给input子系统*/
};
 
struct gpio_event_axis_info {
        /* initialize to gpio_event_axis_func */
        struct gpio_event_info info; /*gpio_event信息*/
        uint8_t  count; /*gpio的数量*/
        uint8_t  type; /* EV_REL or EV_ABS */
        uint16_t code; /*输入键值类型*/
        uint16_t decoded_size; /*gpio 数组的大小*/
        uint16_t (*map)(struct gpio_event_axis_info *info, uint16_t in); /*解析回调函数*/
        uint32_t *gpio; /*gpio端口数组*/
        uint32_t flags; /*调试标值*/
        uint32_t enable_emc_protect_delay; /*保护间隔时间*/
        uint16_t emc_gpio_state; /* 延时中用到gpio_state*/
        atomic_t emc_disable_irqnum;/*延时中用到的屏蔽的中断号*/
};
 
struct gpio_event_info {
        int (*func)(struct input_dev *input_dev,
        struct gpio_event_info *info,
        void **data, int func);
        /*给gpio_event子系统中实现注册到内核中的回调函数*/
        int (*event)(struct input_dev *input_dev,
        struct gpio_event_info *info,
        void **data, unsigned int type,
        unsigned int code, int value); /* out events */
};
 
struct gpio_event_platform_data {
        const char *name;/*名字*/
        struct gpio_event_info **info;/*gpio_event的结构指针*/
        size_t info_count;/*注册到axis中的info 结构体的数量*/
        int (*power)(const struct gpio_event_platform_data *pdata, bool on);/*电源管理回调函数*/
};

/*gpio_event基本数据结构*/
struct gpio_event {
        struct input_dev *input_dev;
        const struct gpio_event_platform_data *info;
        struct early_suspend early_suspend;
        void *state[0];
};
 
/*注册给input的回调函数*/
static int gpio_input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value)
 
/*调用下层给的回调函数来实现具体的注册*/
static int gpio_event_call_all_func(struct gpio_event *ip, int func)
/*电源管理*/
#ifdef CONFIG_HAS_EARLYSUSPEND
void gpio_event_suspend(struct early_suspend *h)
 
void gpio_event_resume(struct early_suspend *h)
#endif
/*注册*/
static int __init gpio_event_probe(struct platform_device *pdev)
/*注销*/
static int gpio_event_remove(struct platform_device *pdev)
 
static struct platform_driver gpio_event_driver
static int __devinit gpio_event_init(void)
 
static void __exit gpio_event_exit(void)

struct gpio_axis_state {
struct input_dev *input_dev;/*input设备结构*/
struct gpio_event_axis_info *info; /*坐标系数据结构*/
uint32_t pos; /*位置*/
struct hrtimer emc_hrtimer_delay; /* 延时时间*/
atomic_t atomic_emc_hrtimer_is_run; /*延时的原子变量*/
};
/*上报input数据*/
static void gpio_event_update_axis(struct gpio_axis_state *as, int report)
/*时间处理函数*/
static enum hrtimer_restart emc_progress_hrtimer_handler_func(struct hrtimer *timer)
/*中断处理函数*/
static irqreturn_t gpio_axis_irq_handler(int irq, void *dev_id)
/*给上层的注册回调函数*/
int gpio_event_axis_func(struct input_dev *input_dev, struct gpio_event_info *info, void **data, int func)

uint16_t hero_axis_map(struct gpio_event_axis_info *info, uint16_t in)
{
        struct hero_axis_info *ai = container_of(info, struct hero_axis_info, info);
        uint16_t out = ai->out_state;
 
if (nav_just_on) {
        if (jiffies == nav_on_jiffies || jiffies == nav_on_jiffies + 1)
                goto ignore;
        nav_just_on = 0;
}
 
if((ai->in_state ^ in) & 1) /*检测在方向1上有没有数值变化*/
        out--;
if((ai->n_state ^ in) & 2) /*检测在方向1相对方向上有没有数值变化*/
        out++;
ai->;out_state = out;
ignore:
        ai->in_state = in;
if (ai->out_state - ai->temp_state == ai->threshold) {
        ai->temp_state++;
        ai->out_state = ai->temp_state;
} else if (ai->temp_state - ai-out_state == ai->threshold) {
        ai->temp_state--;
        ai->out_state = ai->temp_state;
} else if (abs(ai->out_state - ai->;temp_state) > ai->threshold)
        ai->temp_state = ai->out_state;
 
return ai->temp_state;
}

static struct hero_axis_info hero_x_axis = {
        .threshold = 1,
                .info = {
                .info.func = gpio_event_axis_func,
                .count = ARRAY_SIZE(hero_x_axis_gpios),
                .type = EV_REL,
                .code = REL_X,
                .decoded_size = 1U << ARRAY_SIZE(hero_x_axis_gpios),
                .map = hero_axis_map,
                .gpio = hero_x_axis_gpios,
                .flags = GPIOEAF_PRINT_UNKNOWN_DIRECTION /*| GPIOEAF_PRINT_RAW | GPIOEAF_PRINT_EVENT */,
                .enable_emc_protect_delay = 1 * NSEC_PER_MSEC,
        }
};

static struct hero_axis_info hero_y_axis = {
        .threshold = 1,
                .info = {
                .info.func = gpio_event_axis_func,
                .count = ARRAY_SIZE(hero_y_axis_gpios),
                .type = EV_REL,
                .code = REL_Y,
                .decoded_size = 1U << ARRAY_SIZE(hero_y_axis_gpios),
                .map = hero_axis_map,
                .gpio = hero_y_axis_gpios,
                .flags = GPIOEAF_PRINT_UNKNOWN_DIRECTION /*| GPIOEAF_PRINT_RAW | GPIOEAF_PRINT_EVENT  */,
                .enable_emc_protect_delay = 1 * NSEC_PER_MSEC,
        }
};

as->input_dev = input_dev;
as->info = ai;
 
input_set_capability(input_dev, ai->type, ai->;code);
if (ai->type == EV_ABS) {
        input_set_abs_params(input_dev, ai->code, 0,
        ai->decoded_size - 1, 0, 0);
}

[cyher@cyher ~]$ ls /proc/3355/
attr             cpuset   io        mountinfo   pagemap      smaps    task
auxv             cwd      latency   mounts      personality  stack    wchan
cgroup           environ  limits    mountstats  root         stat
clear_refs       exe      loginuid  net         sched        statm
cmdline          fd       maps      oom_adj     schedstat    status
coredump_filter  fdinfo   mem       oom_score   sessionid    syscall

/*
 * =====================================================================================
 *
 *       Filename:  get_exe_path.c
 *
 *    Description:
 *
 *        Version:  1.0
 *        Created:  2009年09月23日 17时07分17秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  cyher (), cyher.net@gmail.com
 *        Company:  cyher.net
 *
 * =====================================================================================
 */
 
#include
#include
#include
#define BUF 128
 
int main(int agrc, char **argv) {
    char buf[BUF];
    char proc[BUF];
    char *p;
 
    sprintf(proc, "/proc/%d/exe", atoi(argv[1]));
    readlink(proc,buf, BUF); /*proc/pid/exe 是一个链接，用readlink读*/
    p = strchr(buf,'('); /*读出的路径后面有可能会有 (deleted)字样，删去*/
    if (p ！= NULL) {
        p--;
        *p = '\0';
    }
    puts(buf);
}