/* Copyright (C) 2010, Lars-Peter Clausen <[email protected]>
* PWM beeper driver
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <linux/input.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
struct pwm_beeper {
struct input_dev *input;
struct pwm_device *pwm;
unsigned long period;
};
#define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
//事件處理函式
static int pwm_beeper_event(struct input_dev *input,
unsigned int type, unsigned int code, int value)
{
int ret = 0;
struct pwm_beeper *beeper = input_get_drvdata(input);
unsigned long period;
if (type != EV_SND || value < 0)
return -EINVAL; //若input_event.type不是EV_SND或input_event.value小於0，則退出
switch (code) {
case SND_BELL:
value = value ? 1000 : 0;
break;
case SND_TONE:
break;
default:
return -EINVAL;
}
if (value == 0) {
pwm_config(beeper->pwm, 0, 0); //配置PWM函式
pwm_disable(beeper->pwm); //關閉PWM函式
} else {
period = HZ_TO_NANOSECONDS(value);
ret = pwm_config(beeper->pwm, period / 2, period);
if (ret)
return ret;
ret = pwm_enable(beeper->pwm);
if (ret)
return ret;
beeper->period = period;
}
return 0;
}
static int __devinit pwm_beeper_probe(struct platform_device *pdev)
{
unsigned long pwm_id = (unsigned long)pdev->dev.platform_data;
struct pwm_beeper *beeper;
int error;
//為蜂鳴器裝置開闢一段記憶體空間，並清零
beeper = kzalloc(sizeof(*beeper), GFP_KERNEL);
if (!beeper)
return -ENOMEM;
beeper->pwm = pwm_request(pwm_id, "pwm beeper"); //申請一個PWM裝置
if (IS_ERR(beeper->pwm)) {
error = PTR_ERR(beeper->pwm);
dev_err(&pdev->dev, "Failed to request pwm device: %d\n", error);
goto err_free;
}
beeper->input = input_allocate_device(); //為輸入裝置結構體分配一個空間,並對其主要的成員進行了初始化.
if (!beeper->input) {
dev_err(&pdev->dev, "Failed to allocate input device\n");
error = -ENOMEM;
goto err_pwm_free;
}
beeper->input->dev.parent = &pdev->dev; //將輸入資訊賦值到輸入子系統
beeper->input->name = "pwm-beeper";
beeper->input->phys = "pwm/input0";
beeper->input->id.bustype = BUS_HOST;
beeper->input->id.vendor = 0x001f;
beeper->input->id.product = 0x0001;
beeper->input->id.version = 0x0100;
beeper->input->evbit[0] = BIT(EV_SND); 

beeper->input->sndbit[0] = BIT(SND_TONE) | BIT(SND_BELL);
beeper->input->event = pwm_beeper_event; //給出 事件處理函式
input_set_drvdata(beeper->input, beeper); 
error = input_register_device(beeper->input);
if (error) 
{
  dev_err(&pdev->dev, "Failed to register input device: %d\n", error);
  goto err_input_free; 
 }
 platform_set_drvdata(pdev, beeper); 
 return 0; 
 err_input_free: input_free_device(beeper->input); 
 err_pwm_free: pwm_free(beeper->pwm); 
 err_free: kfree(beeper); return error; 
 } 
 //移除pwm裝置 
 static int __devexit pwm_beeper_remove(struct platform_device *pdev) 
 {
     struct pwm_beeper *beeper = platform_get_drvdata(pdev);
     platform_set_drvdata(pdev, NULL); 
     input_unregister_device(beeper->input); //解除安裝輸入子系統 
     pwm_disable(beeper->pwm);
     pwm_free(beeper->pwm);
     kfree(beeper); 
     return 0;
 } 
 #ifdef CONFIG_PM 
 static int pwm_beeper_suspend(struct device *dev) 
 { 
     struct pwm_beeper *beeper = dev_get_drvdata(dev);
     if (beeper->period) 
         pwm_disable(beeper->pwm); 
     return 0; 
 } 
 static int pwm_beeper_resume(struct device *dev)
 {
     struct pwm_beeper *beeper = dev_get_drvdata(dev);
     if (beeper->period)
     {   pwm_config(beeper->pwm, beeper->period / 2, beeper->period);
         pwm_enable(beeper->pwm); 
 }
 return 0;
 } 
 static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops, pwm_beeper_suspend, pwm_beeper_resume); 
 #define PWM_BEEPER_PM_OPS (&pwm_beeper_pm_ops) 
 #else 
 #define PWM_BEEPER_PM_OPS NULL 
 #endif 
 //建立平臺驅動，此處name與上面我們在mach-smdk2440.c新增的名字相同，用於匹配 
static struct platform_driver pwm_beeper_driver = { 
     .probe	= pwm_beeper_probe, 
     .remove = __devexit_p(pwm_beeper_remove), 
     .driver = { .name	= "pwm-beeper", 
             .owner	= THIS_MODULE, 
             .pm	= PWM_BEEPER_PM_OPS, 
           }, 
     }; 
 //驅動入口 
static int __init pwm_beeper_init(void) 
{ 
    return platform_driver_register(&pwm_beeper_driver); //註冊平臺驅動 
}
module_init(pwm_beeper_init);
static void __exit pwm_beeper_exit(void)
{ 
    platform_driver_unregister(&pwm_beeper_driver); 
} 
module_exit(pwm_beeper_exit);
MODULE_AUTHOR("Lars-Peter Clausen <
 
[email protected]>");
MODULE_DESCRIPTION("PWM beeper driver"); 
MODULE_LICENSE("GPL"); 
MODULE_ALIAS("platform:pwm-beeper");