学步园

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

    然后设置divider value：

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

2.    接着设置TOUT1的定时器PWM脉宽：

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

 3.   设置完这些就可以开启TOUT1了。代码如下：

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

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

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(<br /> DWORD hOpenContext,<br /> DWORD dwCode,<br /> PBYTE pBufIn,<br /> DWORD dwLenIn,<br /> PBYTE pBufOut,<br /> DWORD dwLenOut,<br /> PDWORD pdwActualOut<br /> )<br /> {<br /> DWORD dwErr = ERROR_INVALID_PARAMETER;<br /> BOOL bRc;</p> <p> RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] IOCTL code = %d/r/n"), dwCode));<br /> switch (dwCode)<br /> {<br /> case IOCTL_POWER_CAPABILITIES: // determines device-specific capabilities<br /> RETAILMSG(DBGBAK, (TEXT("[lqm:BKL] IOCTL_POWER_CAPABILITIES/r/n")));<br /> if (pBufOut && dwLenOut >= sizeof (POWER_CAPABILITIES) && pdwActualOut)<br /> {<br /> __try<br /> {<br /> PPOWER_CAPABILITIES PowerCaps = (PPOWER_CAPABILITIES)pBufOut;<br /> // Right now supports D0 (permanently on) and D4(off) only.<br /> memset(PowerCaps, 0, sizeof(*PowerCaps));<br /> PowerCaps->DeviceDx = 0x12; //support D0, D1, D4<br /> *pdwActualOut = sizeof(*PowerCaps);<br /> bRc = TRUE;<br /> dwErr = ERROR_SUCCESS;<br /> }<br /> __except(EXCEPTION_EXECUTE_HANDLER)<br /> {<br /> RETAILMSG(DBGBAK1, (TEXT("<BKL> exception in ioctl/r/n")));<br /> }<br /> }<br /> else<br /> bRc = FALSE;<br /> break;</p> <p> case IOCTL_POWER_QUERY: // determines whether changing power state is feasible<br /> RETAILMSG(DBGBAK, (TEXT("<BKL> Received IOCTL_POWER_QUERY/r/n")));<br /> if (pBufOut && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))<br /> {<br /> // Return a good status on any valid query, since we are always ready to<br /> // change power states (if asked for state we don't support, we move to next highest, eg D3->D4).<br /> __try<br /> {<br /> CEDEVICE_POWER_STATE ReqDx = *(PCEDEVICE_POWER_STATE)pBufOut;</p> <p> if (VALID_DX(ReqDx))<br /> {<br /> // This is a valid Dx state so return a good status.<br /> bRc = TRUE;<br /> dwErr = ERROR_SUCCESS;<br /> }<br /> else<br /> {<br /> bRc = FALSE;<br /> }<br /> RETAILMSG(DBGBAK, (TEXT("<BKL> IOCTL_POWER_QUERY %s/r/n"), dwErr == ERROR_SUCCESS ? (TEXT("succeeded")) : (TEXT("failed")) ));<br /> }<br /> __except(EXCEPTION_EXECUTE_HANDLER)<br /> {<br /> RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));<br /> }<br /> }<br /> else<br /> bRc = FALSE;<br /> break;</p> <p> case IOCTL_POWER_SET: // requests a change from one device power state to another<br /> RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] Received IOCTL_POWER_SET/r/n")));<br /> if (pBufOut && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))<br /> {<br /> __try<br /> {<br /> CEDEVICE_POWER_STATE ReqDx = *(PCEDEVICE_POWER_STATE)pBufOut;</p> <p> if (VALID_DX(ReqDx))<br /> {<br /> RETAILMSG(lqm_bakdbg,(TEXT("[lqm:BKL] Received IOCTL_POWER_SET=%d/r/n"), ReqDx));<br /> if( ReqDx == (CEDEVICE_POWER_STATE)D2 || ReqDx == (CEDEVICE_POWER_STATE)D3)<br /> bklStatus = (CEDEVICE_POWER_STATE)D4;<br /> else<br /> bklStatus = ReqDx;</p> <p> //SetEvent(g_evtBacklight);<br /> // 调整亮度值后调用函数执行调整<br /> BAK_hw_setBL();<br /> *(PCEDEVICE_POWER_STATE) pBufOut = bklStatus;<br /> *pdwActualOut = sizeof(CEDEVICE_POWER_STATE);<br /> bRc = TRUE;<br /> dwErr = ERROR_SUCCESS;<br /> RETAILMSG(lqm_bakdbg, (TEXT("[lqm:BKL] IOCTL_POWER_SET to D%d /r/n"), ReqDx));<br /> }<br /> else<br /> {<br /> bRc = FALSE;<br /> RETAILMSG(DBGBAK1, (TEXT("<BKL> Invalid state request D%d/r/n"), ReqDx));<br /> }<br /> }<br /> __except(EXCEPTION_EXECUTE_HANDLER)<br /> {<br /> RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));<br /> }<br /> }<br /> else<br /> {<br /> bRc = FALSE;<br /> }<br /> break;</p> <p> case IOCTL_POWER_GET: // gets the current device power state<br /> RETAILMSG(DBGBAK, (TEXT("<BKL> Received IOCTL_POWER_GET/r/n/n")));<br /> if (pBufOut != NULL && dwLenOut >= sizeof(CEDEVICE_POWER_STATE))<br /> {<br /> __try<br /> {<br /> *(PCEDEVICE_POWER_STATE)pBufOut = getBacklightStatus();</p> <p> bRc = TRUE;<br /> dwErr = ERROR_SUCCESS;</p> <p> RETAILMSG(DBGBAK, (TEXT("<BKL> IOCTL_POWER_GET: passing back %u/r/n"), getBacklightStatus()));<br /> }<br /> __except(EXCEPTION_EXECUTE_HANDLER)<br /> {<br /> RETAILMSG(DBGBAK1, (TEXT("<BKL> Exception in ioctl/r/n")));<br /> }<br /> }<br /> else<br /> bRc = FALSE;<br /> break;<br /> // 背光亮度调节<br /> case IOCTL_BACKLIGHT_ADJUST:<br /> if (pBufOut != NULL && (dwLenOut>=sizeof(DWORD)))<br /> {<br /> DWORD dwBackLight = *((DWORD*)pBufOut);<br /> if((BAK_LEVEL_MAX <dwBackLight) || (BAK_LEVEL_MIN > dwBackLight ))<br /> {<br /> *(DWORD*)pBufOut = ERROR_INVALID_PARAMETER;<br /> *pdwActualOut = sizeof(DWORD);</p> <p> bRc = FALSE;<br /> }<br /> else<br /> {<br /> BAK_AdjuctBacklightLevel(*(DWORD*)pBufOut);<br /> // Adjust backlight level.<br /> *(DWORD*)pBufOut = ERROR_SUCCESS;<br /> *pdwActualOut = sizeof(DWORD);<br /> bRc = TRUE;<br /> }<br /> }<br /> else<br /> {<br /> bRc = FALSE;<br /> }<br /> break;<br /> case IOCTL_BACKLIGHT_GETLEVEL:<br /> if (pBufOut != NULL && (dwLenOut>=sizeof(DWORD)))<br /> {<br /> // Return the current backlight level.<br /> *(DWORD*)pBufOut = l_dwBackLightLevel;<br /> *pdwActualOut = sizeof(DWORD);<br /> bRc = TRUE;<br /> }<br /> else<br /> {<br /> bRc = FALSE;<br /> }<br /> break;<br /> }<br /> return(bRc);<br /> }

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。

部分接口的具体调用见下一篇，背光调节的应用程序设计。