基于input子系统的sensor驱动调试（二）

继上一篇：http://www.cnblogs.com/linhaostudy/p/8303628.html#_label1_1

一、驱动流程解析：

1、模块加载：

 static struct of_device_id stk_match_table[] = {
     { .compatible = "stk,stk3x1x", },
     { },
 };

 static struct i2c_driver stk_ps_driver =
 {
     .driver = {
         .name = DEVICE_NAME,
         .owner = THIS_MODULE,
         .of_match_table = stk_match_table,
     },
     .probe = stk3x1x_probe,
     .remove = stk3x1x_remove,
     .id_table = stk_ps_id,
 };

 static int __init stk3x1x_init(void)
 {
     int ret;
     ret = i2c_add_driver(&stk_ps_driver);
     if (ret)
         return ret;

     return ;
 }

 static void __exit stk3x1x_exit(void)
 {
     i2c_del_driver(&stk_ps_driver);
 }

of_device_id与DTS中的匹配，这与内核2.6以前的i2c_board_info不一样；

内核加载驱动模块的时候将调用到stk3x1x_init()方法：

初始化了i2c_driver结构体给stk_ps_driver变量，将用于将设备注册到IIC。关键在于结构体中的probe()方法，注册完成的时候将调用；

2、stk3x1x驱动初始化-probe函数：

 static int stk3x1x_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
 {
     int err = -ENODEV;
     struct stk3x1x_data *ps_data;
     struct stk3x1x_platform_data *plat_data;
     printk(KERN_INFO "%s: driver version = %s\n", __func__, DRIVER_VERSION);

     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
     {
         printk(KERN_ERR "%s: No Support for I2C_FUNC_SMBUS_BYTE_DATA\n", __func__);
         return -ENODEV;
     }
     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
     {
         printk(KERN_ERR "%s: No Support for I2C_FUNC_SMBUS_WORD_DATA\n", __func__);
         return -ENODEV;
     }

     ps_data = kzalloc(sizeof(struct stk3x1x_data),GFP_KERNEL);
     if(!ps_data)
     {
         printk(KERN_ERR "%s: failed to allocate stk3x1x_data\n", __func__);
         return -ENOMEM;
     }
     ps_data->client = client;
     i2c_set_clientdata(client,ps_data);
     mutex_init(&ps_data->io_lock);
     wake_lock_init(&ps_data->ps_wakelock,WAKE_LOCK_SUSPEND, "stk_input_wakelock");

 #ifdef STK_POLL_PS
     wake_lock_init(&ps_data->ps_nosuspend_wl,WAKE_LOCK_SUSPEND, "stk_nosuspend_wakelock");
 #endif
     if (client->dev.of_node) {
         plat_data = devm_kzalloc(&client->dev,
             sizeof(struct stk3x1x_platform_data), GFP_KERNEL);
         if (!plat_data) {
             dev_err(&client->dev, "Failed to allocate memory\n");
             return -ENOMEM;
         }

         err = stk3x1x_parse_dt(&client->dev, plat_data);
         dev_err(&client->dev,
             "%s: stk3x1x_parse_dt ret=%d\n", __func__, err);
         if (err)
             return err;
     } else
         plat_data = client->dev.platform_data;

     if (!plat_data) {
         dev_err(&client->dev,
             "%s: no stk3x1x platform data!\n", __func__);
         goto err_als_input_allocate;
     }
     ps_data->als_transmittance = plat_data->transmittance;
     ps_data->int_pin = plat_data->int_pin;
     ps_data->use_fir = plat_data->use_fir;
     ps_data->pdata = plat_data;

     if (ps_data->als_transmittance == ) {
         dev_err(&client->dev,
             "%s: Please set als_transmittance\n", __func__);
         goto err_als_input_allocate;
     }

     ps_data->als_input_dev = devm_input_allocate_device(&client->dev);
     if (ps_data->als_input_dev==NULL)
     {
         printk(KERN_ERR "%s: could not allocate als device\n", __func__);
         err = -ENOMEM;
         goto err_als_input_allocate;
     }
     ps_data->ps_input_dev = devm_input_allocate_device(&client->dev);
     if (ps_data->ps_input_dev==NULL)
     {
         printk(KERN_ERR "%s: could not allocate ps device\n", __func__);
         err = -ENOMEM;
         goto err_als_input_allocate;
     }
     ps_data->als_input_dev->name = ALS_NAME;
     ps_data->ps_input_dev->name = PS_NAME;
     set_bit(EV_ABS, ps_data->als_input_dev->evbit);
     set_bit(EV_ABS, ps_data->ps_input_dev->evbit);
     input_set_abs_params(ps_data->als_input_dev, ABS_MISC, , stk_alscode2lux(ps_data, (<<)-), , );
     input_set_abs_params(ps_data->ps_input_dev, ABS_DISTANCE, ,, , );
     err = input_register_device(ps_data->als_input_dev);
     if (err<)
     {
         printk(KERN_ERR "%s: can not register als input device\n", __func__);
         goto err_als_input_allocate;
     }
     err = input_register_device(ps_data->ps_input_dev);
     if (err<)
     {
         printk(KERN_ERR "%s: can not register ps input device\n", __func__);
         goto err_als_input_allocate;
     }

     err = sysfs_create_group(&ps_data->als_input_dev->dev.kobj, &stk_als_attribute_group);
     if (err < )
     {
         printk(KERN_ERR "%s:could not create sysfs group for als\n", __func__);
         goto err_als_input_allocate;
     }
     err = sysfs_create_group(&ps_data->ps_input_dev->dev.kobj, &stk_ps_attribute_group);
     if (err < )
     {
         printk(KERN_ERR "%s:could not create sysfs group for ps\n", __func__);
         goto err_ps_sysfs_create_group;
     }
     input_set_drvdata(ps_data->als_input_dev, ps_data);
     input_set_drvdata(ps_data->ps_input_dev, ps_data);

 #ifdef STK_POLL_ALS
     ps_data->stk_als_wq = create_singlethread_workqueue("stk_als_wq");
     INIT_WORK(&ps_data->stk_als_work, stk_als_work_func);
     hrtimer_init(&ps_data->als_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
     ps_data->als_poll_delay = ns_to_ktime( * NSEC_PER_MSEC);
     ps_data->als_timer.function = stk_als_timer_func;
 #endif

     ps_data->stk_ps_wq = create_singlethread_workqueue("stk_ps_wq");
     INIT_WORK(&ps_data->stk_ps_work, stk_ps_work_func);
     hrtimer_init(&ps_data->ps_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
     ps_data->ps_poll_delay = ns_to_ktime( * NSEC_PER_MSEC);
     ps_data->ps_timer.function = stk_ps_timer_func;
 #if (!defined(STK_POLL_ALS) || !defined(STK_POLL_PS))
     ps_data->stk_wq = create_singlethread_workqueue("stk_wq");
     INIT_WORK(&ps_data->stk_work, stk_work_func);
     err = stk3x1x_setup_irq(client);
     if(err < )
         goto err_stk3x1x_setup_irq;
 #endif

     err = stk3x1x_power_init(ps_data, true);
     if (err)
         goto err_power_init;

     err = stk3x1x_power_ctl(ps_data, true);
     if (err)
         goto err_power_on;

     ps_data->als_enabled = false;
     ps_data->ps_enabled = false;
 #ifdef CONFIG_HAS_EARLYSUSPEND
     ps_data->stk_early_suspend.level = EARLY_SUSPEND_LEVEL_BLANK_SCREEN + ;
     ps_data->stk_early_suspend.suspend = stk3x1x_early_suspend;
     ps_data->stk_early_suspend.resume = stk3x1x_late_resume;
     register_early_suspend(&ps_data->stk_early_suspend);
 #endif
     /* make sure everything is ok before registering the class device */
     ps_data->als_cdev = sensors_light_cdev;
     ps_data->als_cdev.sensors_enable = stk_als_enable_set;
     ps_data->als_cdev.sensors_poll_delay = stk_als_poll_delay_set;
     err = sensors_classdev_register(&client->dev, &ps_data->als_cdev);
     if (err)
         goto err_power_on;

     ps_data->ps_cdev = sensors_proximity_cdev;
     ps_data->ps_cdev.sensors_enable = stk_ps_enable_set;
     err = sensors_classdev_register(&client->dev, &ps_data->ps_cdev);
     if (err)
         goto err_class_sysfs;

     /* enable device power only when it is enabled */
     err = stk3x1x_power_ctl(ps_data, false);
     if (err)
         goto err_init_all_setting;

     dev_dbg(&client->dev, "%s: probe successfully", __func__);

     return ;

 err_init_all_setting:
     stk3x1x_power_ctl(ps_data, false);
     sensors_classdev_unregister(&ps_data->ps_cdev);
 err_class_sysfs:
     sensors_classdev_unregister(&ps_data->als_cdev);
 err_power_on:
     stk3x1x_power_init(ps_data, false);
 err_power_init:
 #ifndef STK_POLL_PS
     free_irq(ps_data->irq, ps_data);
     gpio_free(plat_data->int_pin);
 #endif
 #if (!defined(STK_POLL_ALS) || !defined(STK_POLL_PS))
 err_stk3x1x_setup_irq:
 #endif
 #ifdef STK_POLL_ALS
     hrtimer_try_to_cancel(&ps_data->als_timer);
     destroy_workqueue(ps_data->stk_als_wq);
 #endif
     destroy_workqueue(ps_data->stk_ps_wq);
 #if (!defined(STK_POLL_ALS) || !defined(STK_POLL_PS))
     destroy_workqueue(ps_data->stk_wq);
 #endif
     sysfs_remove_group(&ps_data->ps_input_dev->dev.kobj, &stk_ps_attribute_group);
 err_ps_sysfs_create_group:
     sysfs_remove_group(&ps_data->als_input_dev->dev.kobj, &stk_als_attribute_group);
 err_als_input_allocate:
 #ifdef STK_POLL_PS
     wake_lock_destroy(&ps_data->ps_nosuspend_wl);
 #endif
     wake_lock_destroy(&ps_data->ps_wakelock);
     mutex_destroy(&ps_data->io_lock);
     kfree(ps_data);
     return err;
 }

在stk3x1x_probe函数中主要做了：

1、为驱动私有数据结构体stk3x1x_data分配内存空间；

2、 将设备驱动的私有数据(stk3x1x_data)连接到设备client(i2c_client)中；（bma255会增加一步：读取i2c的id）；

3、将stk3x1x驱动注册到linux input子系统；

4、创建工作队列（主要是对sensor的数据采集）；

5、创建sysfs接口；

2.1 创建input子系统：

http://blog.csdn.net/ielife/article/details/7798952

1、 在驱动加载模块中，设置你的input设备支持的事件类型；

2、 注册中断处理函数，例如键盘设备需要编写按键的抬起、放下，触摸屏设备需要编写按下、抬起、绝对移动，鼠标设备需要编写单击、抬起、相对移动，并且需要在必要的时候提交硬件数据（键值/坐标/状态等等）；

3、将输入设备注册到输入子系统中；

 　　ps_data->als_input_dev = devm_input_allocate_device(&client->dev);　　　　//分配内存空间
     if (ps_data->als_input_dev==NULL)
     {
         printk(KERN_ERR "%s: could not allocate als device\n", __func__);
         err = -ENOMEM;
         goto err_als_input_allocate;
     }
     ps_data->ps_input_dev = devm_input_allocate_device(&client->dev);
     if (ps_data->ps_input_dev==NULL)
     {
         printk(KERN_ERR "%s: could not allocate ps device\n", __func__);
         err = -ENOMEM;
         goto err_als_input_allocate;
     }
     ps_data->als_input_dev->name = ALS_NAME;　　　　　
     ps_data->ps_input_dev->name = PS_NAME;
     set_bit(EV_ABS, ps_data->als_input_dev->evbit);
     set_bit(EV_ABS, ps_data->ps_input_dev->evbit);
     input_set_abs_params(ps_data->als_input_dev, ABS_MISC, , stk_alscode2lux(ps_data, (<<)-), , );　　　　//设置input加载类型；
     input_set_abs_params(ps_data->ps_input_dev, ABS_DISTANCE, ,, , );
     err = input_register_device(ps_data->als_input_dev);
     if (err<)
     {
         printk(KERN_ERR "%s: can not register als input device\n", __func__);
         goto err_als_input_allocate;
     }
     err = input_register_device(ps_data->ps_input_dev);
     if (err<)
     {
         printk(KERN_ERR "%s: can not register ps input device\n", __func__);
         goto err_als_input_allocate;
     }

     err = stk3x1x_setup_irq(client);　　　　　　　　//设置驱动中断函数
     if(err < )
         goto err_stk3x1x_setup_irq;

2.2 创建工作队列：

先提一个问题，为什么要创建工作队列？在前面的介绍中我们知道，sensor传感器获取数据后，将数据传给controller的寄存器中，供主控去查询读取数据。所以这里创建的工作队列，就是在一个工作者线程，通过IIC不断的去查询读取controller上的数据。

工作队列的作用就是把工作推后,交由一个内核线程去执行,更直接的说就是如果写了一个函数,而现在不想马上执行它,想在将来某个时刻去执行它,那用工作队列准没错.大概会想到中断也是这样,提供一个中断服务函数,在发生中断的时候去执行,没错,和中断相比,工作队列最大的好处就是可以调度可以睡眠,灵活性更好。

上面代码中我们看到INIT_WORK(&ps_data->stk_ps_work, stk_ps_work_func);，其实是一个宏的定义，在include/linux/workqueue.h中。stk_ps_work_func()就是我们定义的功能函数，用于查询读取Sensor的距离传感器数据的，并上报Input子系统，代码如下：

 static void stk_ps_work_func(struct work_struct *work)
 {
     struct stk3x1x_data *ps_data = container_of(work, struct stk3x1x_data, stk_ps_work);
     uint32_t reading;
     int32_t near_far_state;
     uint8_t org_flag_reg;
     int32_t ret;
     uint8_t disable_flag = ;
     mutex_lock(&ps_data->io_lock);

     org_flag_reg = stk3x1x_get_flag(ps_data);
     if(org_flag_reg < )
     {
         printk(KERN_ERR "%s: get_status_reg fail, ret=%d", __func__, org_flag_reg);
         goto err_i2c_rw;
     }
     near_far_state = (org_flag_reg & STK_FLG_NF_MASK)?:;
     reading = stk3x1x_get_ps_reading(ps_data);
     if(ps_data->ps_distance_last != near_far_state)
     {
         ps_data->ps_distance_last = near_far_state;
         input_report_abs(ps_data->ps_input_dev, ABS_DISTANCE, near_far_state);　　　　//input上报数据
         input_sync(ps_data->ps_input_dev);　　　　　　　　　　　　　　　　　　　　//input_sync（）在这里不起关键作用。但如果是一个触摸屏，即有x坐标和y坐标，则需要通过input_sync（）函数把x和y坐标完整地传递给输入子系统。
         wake_lock_timeout(&ps_data->ps_wakelock, *HZ);
 #ifdef STK_DEBUG_PRINTF
         printk(KERN_INFO "%s: ps input event %d cm, ps code = %d\n",__func__, near_far_state, reading);
 #endif
     }
     ret = stk3x1x_set_flag(ps_data, org_flag_reg, disable_flag);
     if(ret < )
     {
         printk(KERN_ERR "%s:stk3x1x_set_flag fail, ret=%d\n", __func__, ret);
         goto err_i2c_rw;
     }

     mutex_unlock(&ps_data->io_lock);
     return;

 err_i2c_rw:
     mutex_unlock(&ps_data->io_lock);
     msleep();
     return;
 }

2.3 创建sysfs接口：

为什么要创建sysfs接口？在驱动层创建了sysfs接口，HAL层通过这些sysfs接口，对Sensor进行操作，如使能、设置delay等。

DEVICE_ATTR的使用：http://blog.csdn.net/njuitjf/article/details/16849333

函数宏DEVICE_ATTR内封装的是__ATTR(_name,_mode,_show,_stroe)方法：

_show：表示的是读方法，_stroe表示的是写方法。

1、 调用宏DEVICE_ATTR完成对功能函数的注册：

 static struct device_attribute ps_enable_attribute = __ATTR(enable,,stk_ps_enable_show,stk_ps_enable_store);
 static struct device_attribute ps_enable_aso_attribute = __ATTR(enableaso,,stk_ps_enable_aso_show,stk_ps_enable_aso_store);
 static struct device_attribute ps_distance_attribute = __ATTR(distance,,stk_ps_distance_show, stk_ps_distance_store);
 static struct device_attribute ps_offset_attribute = __ATTR(offset,,stk_ps_offset_show, stk_ps_offset_store);
 static struct device_attribute ps_code_attribute = __ATTR(code, , stk_ps_code_show, NULL);
 static struct device_attribute ps_code_thd_l_attribute = __ATTR(codethdl,,stk_ps_code_thd_l_show,stk_ps_code_thd_l_store);
 static struct device_attribute ps_code_thd_h_attribute = __ATTR(codethdh,,stk_ps_code_thd_h_show,stk_ps_code_thd_h_store);
 static struct device_attribute recv_attribute = __ATTR(recv,,stk_recv_show,stk_recv_store);
 static struct device_attribute send_attribute = __ATTR(send,,stk_send_show, stk_send_store);
 static struct device_attribute all_reg_attribute = __ATTR(allreg, , stk_all_reg_show, NULL);

 static struct attribute *stk_ps_attrs [] =
 {
     &ps_enable_attribute.attr,
     &ps_enable_aso_attribute.attr,
     &ps_distance_attribute.attr,
     &ps_offset_attribute.attr,
     &ps_code_attribute.attr,
     &ps_code_thd_l_attribute.attr,
     &ps_code_thd_h_attribute.attr,
     &recv_attribute.attr,
     &send_attribute.attr,
     &all_reg_attribute.attr,
     NULL
 };

 static struct attribute_group stk_ps_attribute_group = {
     .attrs = stk_ps_attrs,
 };

在probe函数中：

 　　err = sysfs_create_group(&ps_data->als_input_dev->dev.kobj, &stk_als_attribute_group);
     if (err < )
     {
         printk(KERN_ERR "%s:could not create sysfs group for als\n", __func__);
         goto err_als_input_allocate;
     }
     err = sysfs_create_group(&ps_data->ps_input_dev->dev.kobj, &stk_ps_attribute_group);
     if (err < )
     {
         printk(KERN_ERR "%s:could not create sysfs group for ps\n", __func__);
         goto err_ps_sysfs_create_group;
     }

到此，完成了sysfs接口的创建，我们可以在根文件系统中看到/sys/class/input/input1/目录，在该目录下我们可以看到多个节点，其中就包含了enable和delay。我们以enable为例子，可以有两种方法完成对Gsensor的使能工作：

3、读取上报数据：

在Android的HAL层，通过对/sys/class/input/input3/enable节点的写操作，使能sensor。调用到的方法是stk_ps_enable_store函数：

 static struct device_attribute ps_enable_attribute = __ATTR(enable,,stk_ps_enable_show,stk_ps_enable_store);
 static struct device_attribute ps_enable_aso_attribute = __ATTR(enableaso,,stk_ps_enable_aso_show,stk_ps_enable_aso_store);
 static struct device_attribute ps_distance_attribute = __ATTR(distance,,stk_ps_distance_show, stk_ps_distance_store);
 static struct device_attribute ps_offset_attribute = __ATTR(offset,,stk_ps_offset_show, stk_ps_offset_store);
 static struct device_attribute ps_code_attribute = __ATTR(code, , stk_ps_code_show, NULL);
 static struct device_attribute ps_code_thd_l_attribute = __ATTR(codethdl,,stk_ps_code_thd_l_show,stk_ps_code_thd_l_store);
 static struct device_attribute ps_code_thd_h_attribute = __ATTR(codethdh,,stk_ps_code_thd_h_show,stk_ps_code_thd_h_store);
 static struct device_attribute recv_attribute = __ATTR(recv,,stk_recv_show,stk_recv_store);
 static struct device_attribute send_attribute = __ATTR(send,,stk_send_show, stk_send_store);
 static struct device_attribute all_reg_attribute = __ATTR(allreg, , stk_all_reg_show, NULL);

里面的show和store函数；

 static ssize_t stk_ps_enable_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size)
 {
     struct stk3x1x_data *ps_data =  dev_get_drvdata(dev);
     uint8_t en;
     if (sysfs_streq(buf, ""))
         en = ;
     else if (sysfs_streq(buf, ""))
         en = ;
     else
     {
         printk(KERN_ERR "%s, invalid value %d\n", __func__, *buf);
         return -EINVAL;
     }
     dev_dbg(dev, "%s: Enable PS : %d\n", __func__, en);
     mutex_lock(&ps_data->io_lock);
     stk3x1x_enable_ps(ps_data, en);
     mutex_unlock(&ps_data->io_lock);
     return size;
 }

 static int32_t stk3x1x_enable_ps(struct stk3x1x_data *ps_data, uint8_t enable)
 {
     int32_t ret;
     uint8_t w_state_reg;
     uint8_t curr_ps_enable;
     curr_ps_enable = ps_data->ps_enabled?:;
     if(curr_ps_enable == enable)
         return ;

     if (enable) {
         ret = stk3x1x_device_ctl(ps_data, enable);
         if (ret)
             return ret;
     }

     ret = i2c_smbus_read_byte_data(ps_data->client, STK_STATE_REG);
     if (ret < )
     {
             printk(KERN_ERR "%s: write i2c error, ret=%d\n", __func__, ret);
         return ret;
     }
     w_state_reg = ret;
     w_state_reg &= ~(STK_STATE_EN_PS_MASK | STK_STATE_EN_WAIT_MASK | 0x60);
     if(enable)
     {
         w_state_reg |= STK_STATE_EN_PS_MASK;
         if(!(ps_data->als_enabled))
             w_state_reg |= STK_STATE_EN_WAIT_MASK;
     }
     ret = i2c_smbus_write_byte_data(ps_data->client, STK_STATE_REG, w_state_reg);
     if (ret < )
     {
         printk(KERN_ERR "%s: write i2c error, ret=%d\n", __func__, ret);
         return ret;
     }

     if(enable)
     {
 #ifdef STK_POLL_PS
         hrtimer_start(&ps_data->ps_timer, ps_data->ps_poll_delay, HRTIMER_MODE_REL);　　　　//定时一段时间后，开始开启工作队列
         ps_data->ps_distance_last = -;
 #endif
         ps_data->ps_enabled = true;
 #ifndef STK_POLL_PS
 #ifndef STK_POLL_ALS
         if(!(ps_data->als_enabled))
 #endif    /* #ifndef STK_POLL_ALS    */
             enable_irq(ps_data->irq);
         msleep();
         ret = stk3x1x_get_flag(ps_data);
         if (ret < )
         {
             printk(KERN_ERR "%s: read i2c error, ret=%d\n", __func__, ret);
             return ret;
         }

         near_far_state = ret & STK_FLG_NF_MASK;
         ps_data->ps_distance_last = near_far_state;
         input_report_abs(ps_data->ps_input_dev, ABS_DISTANCE, near_far_state);
         input_sync(ps_data->ps_input_dev);
         wake_lock_timeout(&ps_data->ps_wakelock, *HZ);
         reading = stk3x1x_get_ps_reading(ps_data);
         dev_dbg(&ps_data->client->dev,
             "%s: ps input event=%d, ps code = %d\n",
             __func__, near_far_state, reading);
 #endif    /* #ifndef STK_POLL_PS */
     }
     else
     {
 #ifdef STK_POLL_PS
         hrtimer_cancel(&ps_data->ps_timer);
 #else
 #ifndef STK_POLL_ALS
         if(!(ps_data->als_enabled))
 #endif
             disable_irq(ps_data->irq);
 #endif
         ps_data->ps_enabled = false;
     }
     if (!enable) {
         ret = stk3x1x_device_ctl(ps_data, enable);
         if (ret)
             return ret;
     }

     return ret;
 }

 static enum hrtimer_restart stk_als_timer_func(struct hrtimer *timer)
 {
     struct stk3x1x_data *ps_data = container_of(timer, struct stk3x1x_data, als_timer);
     queue_work(ps_data->stk_als_wq, &ps_data->stk_als_work);　　　　　　　　//开启工作队列
     hrtimer_forward_now(&ps_data->als_timer, ps_data->als_poll_delay);
     return HRTIMER_RESTART;
 }

那么对于HAL层，将通过/dev/input/event1设备节点读取到sensor数据。到此，sensor驱动的工作流程完毕。应该很好理解吧！