基于S3C2450 + WINCE的背光驱动及背光亮度调节应用程序移植详解之驱动篇

 背光驱动程序设计

 

1. 这里硬件接口使用S3C2450的GPB1，即定时器1.

    定时器的输入频率 = PCLK /{prescaler value + 1} / {divider value}。

    首先设置prescaler value：

   

 static void BAK_SetPrescaleAndMux( DWORD v_Prescale, DWORD v_Mux )
 {
     // Set prescale.
     if(v_Prescale<=255)
     {
         v_pPWMRegs->TCFG0 = v_pPWMRegs->TCFG0 & (~0xff) | v_Prescale;
     }
     // Set divider value.Timer1 is used
     switch(v_Mux)
     {
     case 1:// 1/2
         v_pPWMRegs->TCFG1 = v_pPWMRegs->TCFG1 & (~0xF0) | (0x0<<4);
         break;
     case 2:// 1/4
         v_pPWMRegs->TCFG1 = v_pPWMRegs->TCFG1 & (~0xF0) | (0x1<<4);
         break;
     case 3:// 1/8
         v_pPWMRegs->TCFG1 = v_pPWMRegs->TCFG1 & (~0xF0) | (0x2<<4);
         break;
     case 4:// 1/16
         v_pPWMRegs->TCFG1 = v_pPWMRegs->TCFG1 & (~0xF0) | (0x3<<4);
         break;
     case 5:
     default:// External TCLK0
         v_pPWMRegs->TCFG1 = v_pPWMRegs->TCFG1 & (~0xF0) | (0x4<<4);
         break;
     }
 }

    然后设置divider value：

   

 static  void BAK_SetTCNTB( DWORD v_Tcntb)
 {
     if(v_Tcntb<=0xffff)
     {
         v_pPWMRegs->TCNTB1 = v_Tcntb;
     }
 }

2.    接着设置TOUT1的定时器PWM脉宽：

 static void BAK_SetTCMPB( DWORD v_Tcmpb)
 {
     if(v_Tcmpb<=0xffff)
     {
         v_pPWMRegs->TCMPB1 = v_Tcmpb;
     }
 }

 3.   设置完这些就可以开启TOUT1了。代码如下：

 static void BAK_StartPwmTimer( void )
 {
     // Set GPB1 to TOUT1.
     v_pIOPregs->GPBCON &= ~(0x03<<2);
     v_pIOPregs->GPBCON |= (0x02<<2);
     // Stop pwm timer 1, first.
     v_pPWMRegs->TCON &= ~(0xF<<8);
     v_pPWMRegs->TCON |= (0x6<<8);  // 这里0x2<<8也OK吧!!!!!
     // Start it again.
     v_pPWMRegs->TCON &= ~(0xF<<8);
     v_pPWMRegs->TCON |= (0x9<<8);
 }

 4.   背光亮度调节代码如下（将亮度设置为10个级别）：

 static void BAK_AdjuctBacklightLevel(DWORD v_Level)
 {
     if((v_Level>=BAK_LEVEL_MIN)&&(v_Level<=BAK_LEVEL_MAX))// v_Level=[1:10]
     {
         l_dwBackLightLevel = v_Level;
         BAK_SetTCMPB((l_dwTcntb * la_dwLevel[v_Level-1])/100);
     }
 }

5.以上事情都做完了后，就可以编写通用的流接口程序了。由于程序比较简单，这里

仅贴上XXX_IOControl的代码如下：

 BOOL BAK_IOControl(
         DWORD hOpenContext,
         DWORD dwCode,
         PBYTE pBufIn,
         DWORD dwLenIn,
         PBYTE pBufOut,
         DWORD dwLenOut,
         PDWORD pdwActualOut
         )
 {
     DWORD dwErr = ERROR_INVALID_PARAMETER;
     BOOL bRc;

     RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] IOCTL code  = %d/r/n"), dwCode));
     switch (dwCode)
     {
     case IOCTL_POWER_CAPABILITIES:  // determines device-specific capabilities
         RETAILMSG(DBGBAK, (TEXT("[lqm:BKL] IOCTL_POWER_CAPABILITIES/r/n")));
         if (pBufOut && dwLenOut >= sizeof (POWER_CAPABILITIES) && pdwActualOut)
         {
             __try
             {
                 PPOWER_CAPABILITIES PowerCaps = (PPOWER_CAPABILITIES)pBufOut;
                 // Right now supports D0 (permanently on) and D4(off) only.
                 memset(PowerCaps, 0, sizeof(*PowerCaps));
                 PowerCaps->DeviceDx = 0x12; //support D0, D1,  D4
                 *pdwActualOut = sizeof(*PowerCaps);
                 bRc = TRUE;
                 dwErr = ERROR_SUCCESS;
             }
             __except(EXCEPTION_EXECUTE_HANDLER)
             {
                 RETAILMSG(DBGBAK1, (TEXT("<BKL> exception in ioctl/r/n")));
             }
         }
         else
             bRc = FALSE;
         break;

     case IOCTL_POWER_QUERY: // determines whether changing power state is feasible
         RETAILMSG(DBGBAK, (TEXT("<BKL> Received IOCTL_POWER_QUERY/r/n")));
         if (pBufOut && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))
         {
             // Return a good status on any valid query, since we are always ready to
             // change power states (if asked for state we don't support, we move to next highest, eg D3->D4).
             __try
             {
                 CEDEVICE_POWER_STATE ReqDx = *(PCEDEVICE_POWER_STATE)pBufOut;

                 if (VALID_DX(ReqDx))
                 {
                     // This is a valid Dx state so return a good status.
                     bRc = TRUE;
                     dwErr = ERROR_SUCCESS;
                 }
                 else
                 {
                     bRc = FALSE;
                 }
                 RETAILMSG(DBGBAK, (TEXT("<BKL> IOCTL_POWER_QUERY %s/r/n"), dwErr == ERROR_SUCCESS ? (TEXT("succeeded")) : (TEXT("failed")) ));
             }
             __except(EXCEPTION_EXECUTE_HANDLER)
             {
                 RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));
             }
         }
         else
             bRc = FALSE;
         break;

     case IOCTL_POWER_SET: // requests a change from one device power state to another
          RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] Received IOCTL_POWER_SET/r/n")));
         if (pBufOut && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))
         {
             __try
             {
                 CEDEVICE_POWER_STATE ReqDx = *(PCEDEVICE_POWER_STATE)pBufOut;

                 if (VALID_DX(ReqDx))
                 {
                     RETAILMSG(lqm_bakdbg,(TEXT("[lqm:BKL] Received IOCTL_POWER_SET=%d/r/n"), ReqDx));
                     if( ReqDx == (CEDEVICE_POWER_STATE)D2 || ReqDx == (CEDEVICE_POWER_STATE)D3)
                     bklStatus = (CEDEVICE_POWER_STATE)D4;
                     else
                     bklStatus = ReqDx;

                     //SetEvent(g_evtBacklight);
                     // 调整亮度值后调用函数执行调整
                     BAK_hw_setBL();
                     *(PCEDEVICE_POWER_STATE) pBufOut = bklStatus;
                     *pdwActualOut = sizeof(CEDEVICE_POWER_STATE);
                     bRc = TRUE;
                     dwErr = ERROR_SUCCESS;
                     RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] IOCTL_POWER_SET to D%d /r/n"), ReqDx));
                 }
                 else
                 {
                     bRc = FALSE;
                     RETAILMSG(DBGBAK1, (TEXT("<BKL> Invalid state request D%d/r/n"), ReqDx));
                 }
             }
             __except(EXCEPTION_EXECUTE_HANDLER)
             {
                 RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));
             }
         }
         else
         {
             bRc = FALSE;
         }
         break;

     case IOCTL_POWER_GET: // gets the current device power state
         RETAILMSG(DBGBAK, (TEXT("<BKL> Received IOCTL_POWER_GET/r/n/n")));
         if (pBufOut != NULL && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))
         {
             __try
             {
                 *(PCEDEVICE_POWER_STATE)pBufOut = getBacklightStatus();

                 bRc = TRUE;
                 dwErr = ERROR_SUCCESS;

                 RETAILMSG(DBGBAK, (TEXT("<BKL> IOCTL_POWER_GET: passing back %u/r/n"), getBacklightStatus()));
             }
             __except(EXCEPTION_EXECUTE_HANDLER)
             {
                 RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));
             }
         }
         else
             bRc = FALSE;
         break;
     // 背光亮度调节
     case IOCTL_BACKLIGHT_ADJUST:
          if (pBufOut != NULL && (dwLenOut>=sizeof(DWORD)))
          {
             DWORD dwBackLight = *((DWORD*)pBufOut);
             if((BAK_LEVEL_MAX <dwBackLight) || (BAK_LEVEL_MIN > dwBackLight ))
             {
                 *(DWORD*)pBufOut = ERROR_INVALID_PARAMETER;
                 *pdwActualOut = sizeof(DWORD);

                 bRc = FALSE;
             }
             else
             {
                 BAK_AdjuctBacklightLevel(*(DWORD*)pBufOut);
                 // Adjust backlight level.
                 *(DWORD*)pBufOut = ERROR_SUCCESS;
                 *pdwActualOut = sizeof(DWORD);
                 bRc = TRUE;
             }
          }
          else
          {
             bRc = FALSE;
          }
         break;
     case IOCTL_BACKLIGHT_GETLEVEL:
          if (pBufOut != NULL && (dwLenOut>=sizeof(DWORD)))
          {
             // Return the current backlight level.
             *(DWORD*)pBufOut = l_dwBackLightLevel;
             *pdwActualOut = sizeof(DWORD);
             bRc = TRUE;
          }
          else
          {
             bRc = FALSE;
          }
         break;
      }
     return(bRc);
 }

 

可以看到有如下几个case：

IOCTL_POWER_CAPABILITIES；

IOCTL_POWER_QUERY；

IOCTL_POWER_SET；

IOCTL_POWER_GET；

IOCTL_BACKLIGHT_ADJUST；

IOCTL_BACKLIGHT_GETLEVEL；

其中

IOCTL_POWER_CAPABILITIES：代表电源管理器请求设备驱动返回设备支持的电源状态及相关特征；

IOCTL_POWER_SET：请求驱动更新设备的电源状态；
IOCTL_POWER_QUERY：电源管理器询问设备是否准备好进行状态切换；
IOCTL_POWER_GET：请求驱动返回当前设备的电源状态；

IOCTL_BACKLIGHT_ADJUST：调节背光亮度的接口；

IOCTL_BACKLIGHT_GETLEVEL：获取背光亮度级别的接口。