基于MTK65xx平台lcm和背光驱动的编写.doc

基于MTK65xx平台lcm和背光驱动的编写一、 与LCD驱动相关的主要文件路径mediatekplatformmt6573ubootmt6573_disp_drv.cmediatekplatformmt6573ubootmt6573_disp_drv_dpi.cmediatekplatformmt6573uboot mt6573_disp_drv_dbi.cmediatekplatformmt6573uboot mt6573_dpi_drv.cmediatekplatformmt6573uboot mt6573_dsi_drv.cmediatekplatformmt6573uboot mt6573_lcd_drv.cmediateksourcekerneldriversvideomtkfb.cmediateksourcekerneldriversvideodisp_drv.cmediateksourcekerneldriversvideodisp_drv_dpi.cmediateksourcekerneldriversvideodisp_drv_dbi.cmediatekplatformmt6573kerneldriversvideolcd_drv.cmediatekplatformmt6573kerneldriversvideodpi_drv.cmediatekplatformmt6573kerneldriversvideodsi_drv.cmediatekcustomcommonkernellcmLCM_NAMELCM_NAME.cmediatekplatformmt6573uboot mt6573_pwm.cmediatekplatformmt6573uboot mt65xx_leds.cmediateksourcekerneldriversledsleds.cmediatekcustomginwave73_gbkernelledsmt65xxcust_leds.c二、 怎样新建一个LCD驱动LCD模组主要包括LCD显示屏和驱动IC。比如LF040DNYB16a模组的驱动IC型号为NT35510。要在MTK6573平台上新建这个lcd的驱动，步骤如下：1、 在mediatekcustomcommonkernellcm目录下新建文件夹nt35510,在此文件夹中新建nt35510.c。这就是LCM硬件层驱动文件。2、 修改mediatekcustomcommonkernellcm mt65xx_lcm_list.c, 在 lcm_driver_list lcm_count 中增加nt35510_lcm_drv。3、 打开mediatekconfigginwave73_gbProjectConfig.mk，修改CUSTOM_UBOOT_LCM = nt35510, CUSTOM_KERNEL_LCM = nt35510；修改LCM_WIDTH、LCM_HEIGHT、BOOT_LOGO为正确的值。三、 驱动文件（nt35510.c） 主要任务是实现LCM_DRIVER nt35510_lcm_drv = .name = nt35510,.set_util_funcs = lcm_set_util_funcs,.get_params = lcm_get_params,.init = lcm_init,.suspend = lcm_suspend,.resume = lcm_resume,.compare_id = lcm_compare_id,;（1）lcm_get_params主要是设置LCM相关的参数，数据结构如下：typedef struct LCM_TYPE type;LCM_CTRL ctrl; /! how to control LCM registers unsigned int width; unsigned int height;unsigned int io_select_mode; /DBI or DPI should select IO mode according to chip spec/* particular parameters */ LCM_DBI_PARAMS dbi; LCM_DPI_PARAMS dpi; LCM_DSI_PARAMS dsi; LCM_PARAMS;LCM_TYPE 定义LCM与HOST间的接口，主要分为3种，DBI, DPI, DSI。其中DBI又分为parallel DBI 和serial DBI。parallel DBI（B型DBI）的命令和数据都在数据总线D17:0上传输。CSX为低时数据有效。WRX线控制D17:0为写时序，RDX控制D17:0为读时序。D/CX指示D17:0上传输的是命令还是数据。注：MT6573使用LPA0线作为D/CX线，LPCE线作为CSX线，LWRB线作为WRX线，LRDB线作为RDX线。serial DBI（C型DBI）的命令和数据都在SPI接口上传输。CSX为低时SDA有效。SCL提供时钟，DIN输入，DOUT输出。当SDA_EN=1时，DIN线成为双向的SDA线，即可输入又可输出，DOUT线不用。C型DBI分为3线(没有D/CX线)和4线（有D/CX线）两种。3线的使用一个D/CX bit来区分命令/数据，4线的使用D/CX线来区分命令/数据。注：MT6573使用LSA0线作为D/CX线，LSCE线作为CSX线。LSCK线作为SCL线，LSDA线作为SDA线。DPI的命令在SPI上传输，Pixel data(RGB data)在D17:0上传输。其命令传输方式与serial DBI相同。对于Pixel data(RGB data)，需要自己的4条控制线：DPICK_PIN(RGB时钟) 、DPIDE_PIN（RGB数据有效）、 DPIVSYNC(场同步)、 DPIHSYNC(行同步) 。typedef enum LCM_CTRL_NONE = 0, LCM_CTRL_SERIAL_DBI, LCM_CTRL_PARALLEL_DBI, LCM_CTRL_GPIOLCM_CTRL定义LCM与HOST之间传递command的方式，有SERIAL_DBI、PARALLEL_DBI、GPIO几种控制方式。如果是DPI接口，其LCM_CTRL可以选择SERIAL_DBI或者GPIO。Width和height定义LCM的宽度和高度。io_select_mode有这些选项：0（LCD_IO_SEL_16CPU_24RGB），1（LCD_IO_SEL_18CPU_18RGB），2（LCD_IO_SEL_24CPU_8RGB），3（LCD_IO_SEL_24CPU_ONLY）。根据driver IC 的定义填写。LCM_PARAMS根据不同的LCM_TYPE取值，这是针对DBI/DPI/DSI接口类型的详细参数定义。比如LCM_DPI_PARAMS定义如下：typedef struct unsigned int mipi_pll_clk_ref; / 0.1 unsigned int mipi_pll_clk_div1; / 0.63 unsigned int mipi_pll_clk_div2; / 0.15 unsigned int dpi_clk_div; / 2.32 unsigned int dpi_clk_duty; / (dpi_clk_div - 1) . 31 /* polarity parameters */ LCM_POLARITY clk_pol; LCM_POLARITY de_pol; LCM_POLARITY vsync_pol; LCM_POLARITY hsync_pol; /* timing parameters */ unsigned int hsync_pulse_width; unsigned int hsync_back_porch; unsigned int hsync_front_porch; unsigned int vsync_pulse_width; unsigned int vsync_back_porch; unsigned int vsync_front_porch; /* output format parameters */ LCM_DPI_FORMAT format; LCM_COLOR_ORDER rgb_order; unsigned int is_serial_output; /* intermediate buffers parameters */ unsigned int intermediat_buffer_num; / 2.3 /* iopad parameters */ LCM_DRIVING_CURRENT io_driving_current; LCM_DPI_PARAMS;其中，第一段前4项用于控制DPI时钟，计算公式如下：Pixel Clock Frequency = 26MHz * mipi_pll_clk_div1 / (mipi_pll_clk_ref + 1)/ (2 * mipi_pll_clk_div2)/ dpi_clk_div第二段4个参数设置DPICK_PIN(RGB时钟) 、DPIDE_PIN（RGB数据有效）、 DPIVSYNC(场同步)、 DPIHSYNC(行同步)线是上升沿还是下降沿有效。行同步脉冲开始前和开始后的几个时钟周期，是行信号消隐期；场同步开始前和开始后的几个行周期，是场信号消隐期。消隐期不传递图像信号。消隐期特性由第三段六个参数定义：hsync_pulse_width; hsync_back_porch; hsync_front_porch; vsync_pulse_width; vsync_back_porch; vsync_front_porch;LCM_DPI_FORMAT指定每个像素中RGB各占几个bit.LCM_COLOR_ORDER指定RGB的顺序。上述参数的值，均依照LCM spec及驱动IC datasheet中的定义。这里要说说一个特别之处。NT35510使用DPI接口，SERIAL_DBI ctrl 方式时，没有D/CX线，datasheet上定义的传输方式是9 bits，即在数据byte前加个D/CX bit。但使用了NT35510的LCMLF040DNYB16a，其spec中却另外定义了其串口使用16 bits 模式传输。Byte1 是标志byte, 前3位分别为 R/W bit, D/CX bit, High/Low bit；Byte2 则是命令或数据。NT35510的每个command长度为2byte，还可能带有若干bytes的参数，比如命令F001,参数AA，应该这样传输：0x20 0xF0 0x00 0x01 0x40 0xAA。（2）lcm_init主要实现LCM的初始化，包括如下步骤：config_gpio配置GPIO。发送reset信号。RESET pin low和RESET pin high需要持续的时间一般为若干ms, 以datasheet 为准。init_lcm_registers初始化LCM的寄存器。具体可以厂家提供的初始代码为参考。一般在此函数末尾，都会使用唤醒命令组（见后文），使LCM进入工作状态。（3）lcm_suspend 使LCM休眠，使用特定的命令，并遵守datasheet定义的时间特性。常用命令组如下：0X2800 (or 0X28) set display off0X1000 (or 0X10) enter sleep mode对nt35510而言，还有一种更深睡眠的状态deep standby mode，使用如下命令进入：0X4F00 0X01（4）lcm_resume使LCM苏醒，使用特定的命令，并遵守datasheet定义的时间特性。唤醒命令组：0X1100 (or 0X11) exit sleep mode0X2900 (or 0X29) set display on对nt35510而言，如果在lcm_suspend中使LCM enter deep standby mode，则不能使用唤醒命令组，需要使用reset信号并要重新init_lcm_registers。四、 驱动 nt35510_lcm_drv怎样被上层使用Mtkfb.c中实现了LCM的platform driver：static struct platform_driver mtkfb_driver = .driver = .name = “mtk-fb”, .bus = &platform_bus_type, .probe = mtkfb_probe, .remove = mtkfb_remove, .suspend = mtkfb_suspend, .resume = mtkfb_resume, ,;mtkfb_probe会调用函数mtkfb_find_lcm_driver来发现LCM的硬件层驱动。mtkfb_find_lcm_driverDISP_SelectDevicedisp_drv_get_lcm_driver，检查lcm_driver_list, 得到当前使用的LCM及其驱动名称。Mt6573_devs.c中，定义了framebuffer型的platform device，这个设备在mt6573_board_init()调用时被注册。它所对应的驱动就是上文提到的mtkfb_driverstatic struct platform_device mt6573_device_fb = .name = mtkfb, .id = 0, .num_resources = ARRAY_SIZE(resource_fb), .resource = resource_fb, .dev = .dma_mask = &mtkfb_dmamask, .coherent_dma_mask = 0xffffffff, ,;在linux 内核中lcd 设备驱动所使用的是framebuffer设备类型，framebuffer设备驱动程序的核心数据结构是fb_ops；用户空间就是通过此结构体，调用其中的函数来对LCD实现控制。Mtkfb.c中定义并实现了fb_ops类型的mtkfb_ops。一个使用mtkfb_ops的例子见mediateksourcekerneldriversgpupvrservices43rdpartymtklfb mtklfb_displayclass.c。static struct fb_ops mtkfb_ops = .owner = THIS_MODULE, .fb_open = mtkfb_open, .fb_release = mtkfb_release, .fb_setcolreg = mtkfb_setcolreg, /批量配置颜色参数 .fb_pan_display = mtkfb_pan_display_proxy, /虚拟屏幕内容显示 .fb_fillrect = cfb_fillrect, /填充区域显示 .fb_copyarea = cfb_copyarea, /复制区域显示 .fb_imageblit = cfb_imageblit, /显示图象 .fb_cursor = mtkfb_soft_cursor, /光标显示 .fb_check_var = mtkfb_check_var, /检查并配置fb_var_screeninfo参数 .fb_set_par = mtkfb_set_par, /change display mode and set parameter .fb_ioctl = mtkfb_ioctl, /特定ioctl配置LCD屏幕特性;五、 Frame Buffer 设备驱动mtkfb_driver中的各个函数会调用到DISP_xxx函数（DISP_drv.c）,而DISP_xxx会调用到LCD_xxx函数（lcd_drv.c）以及LCM硬件层驱动。mtkfb_probe的主要工作如下：* find lcm driver* Register interrupt handler (call back function), Init screen update wait queue, create screen update kThread* Allocate and initialize frame buffer device (fb_info , mtkfb_device), select panel type according to machine type* Initialize Display Driver PDD Layer (DISP_init)* Initialize fb_info struct (mtkfb_fbinfo_init)* Register mtkfb_device fs to system (mtkfb_register_sysfs)* Register fb_info to system (register_framebuffer)fb_info结构定义如下：struct fb_info int node;int flags;struct mutex lock; /* Lock for open/release/ioctl funcs */struct mutex mm_lock; /* Lock for fb_mmap and smem_* fields */struct fb_var_screeninfo var; /* Current var */struct fb_fix_screeninfo fix; /* Current fix */struct fb_monspecs monspecs; /* Current Monitor specs */struct work_struct queue; /* Framebuffer event queue */struct fb_pixmap pixmap; /* Image hardware mapper */struct fb_pixmap sprite; /* Cursor hardware mapper */struct fb_cmap cmap; /* Current cmap */struct list_head modelist; /* mode list */struct fb_videomode *mode; /* current mode */#ifdef CONFIG_FB_BACKLIGHTstruct backlight_device *bl_dev;struct mutex bl_curve_mutex;u8 bl_curveFB_BACKLIGHT_LEVELS;#endif#ifdef CONFIG_FB_DEFERRED_IOstruct delayed_work deferred_work;struct fb_deferred_io *fbdefio;#endifstruct fb_ops *fbops;struct device *device; /* This is the parent */struct device *dev; /* This is this fb device */int class_flag; /* private sysfs flags */#ifdef CONFIG_FB_TILEBLITTINGstruct fb_tile_ops *tileops; /* Tile Blitting */#endifchar _iomem *screen_base; /* Virtual address */unsigned long screen_size; /* Amount of ioremapped VRAM or 0 */void *pseudo_palette; /* Fake palette of 16 colors */#define FBINFO_STATE_RUNNING 0#define FBINFO_STATE_SUSPENDED 1u32 state; /* Hardware state i.e suspend */void *fbcon_par; /* fbcon use-only private area */* From here on everything is device dependent */void *par;struct apertures_struct unsigned int count;struct aperture resource_size_t base;resource_size_t size; ranges0; *apertures;1）fb_var_screeninfo这个结构描述了显示卡的特性：NOTE: _u32 是表示 unsigned 不带符号的 32 bits 的数据类型，其余类推。这是 Linux 内核中所用到的数据类型，如果是开发用户空间（user-space）的程序，可以根据具体计算机平台的情况，用 unsigned long 等等来代替struct fb_var_screeninfo_u32 xres; /* visible resolution */ /可视区域_u32 yres;_u32 xres_virtual; /* virtual resolution */ /可视区域_u32 yres_virtual;_u32 xoffset; /* offset from virtual to visible resolution */ /可视区域的偏移_u32 yoffset;_u32 bits_per_pixel; /* guess what */ /每一象素的bit数_u32 grayscale; /* != 0 Gray levels instead of colors */等于零就成黑白struct fb_bitfield red; /* bitfield in fb mem if true color, */真彩的bit机构struct fb_bitfield green; /* else only length is significant */struct fb_bitfield blue;struct fb_bitfield transp; /* transparency */ 透明_u32 nonstd; /* != 0 Non standard pixel format */ 不是标准格式_u32 activate; /* see FB_ACTIVATE_* */_u32 height; /* height of picture in mm */ 内存中的图像高度_u32 width; /* width of picture in mm */ 内存中的图像宽度_u32 accel_flags; /* acceleration flags (hints) */ 加速标志/* Timing: All values in pixclocks, except pixclock (of course) */时序-_-这些部分就是显示器的显示方法了，可以找相关的资料看看_u32 pixclock; /* pixel clock in ps (pico seconds) */_u32 left_margin; /* time from sync to picture */_u32 right_margin; /* time from picture to sync */_u32 upper_margin; /* time from sync to picture */_u32 lower_margin;_u32 hsync_len; /* length of horizontal sync */ 水平可视区域_u32 vsync_len; /* length of vertical sync */ 垂直可视区域_u32 sync; /* see FB_SYNC_* */_u32 vmode; /* see FB_VMODE_* */_u32 reserved6; /* Reserved for future compatibility */ 备用以后开发;2) fb_fix_screeninfon这个结构在显卡被设定模式后创建，它描述显示卡的属性，并且系统运行时不能被修改；比如FrameBuffer内存的起始地址。它依赖于被设定的模式，当一个模式被设定后，内存信息由显示卡硬件给出，内存的位置等信息就不可以修改。struct fb_fix_screeninfo char id16; /* identification string eg TT Builtin */IDunsigned long smem_start; /* Start of frame buffer mem */ 内存起始/* (physical address) */ 物理地址_u32 smem_len; /* Length of frame buffer mem */ 内存大小_u32 type; /* see FB_TYPE_* */_u32 type_aux; /* Interleave for interleaved Planes */插入区域？_u32 visual; /* see FB_VISUAL_* */_u16 xpanstep; /* zero if no hardware panning */没有硬件设备就为零_u16 ypanstep; /* zero if no hardware panning */_u16 ywrapstep; /* zero if no hardware ywrap */_u32 line_length; /* length of a line in bytes */ 一行的字节表示unsigned long mmio_start; /* Start of Memory Mapped I/O */内存映射的I/O起始/* (physical address) */_u32 mmio_len; /* Length of Memory Mapped I/O */ I/O的大小_u32 accel; /* Type of acceleration available */ 可用的加速类型_u16 reserved3; /* Reserved for future compatibility */;Mtkfb_device结构定义如下：struct mtkfb_device int state; void *fb_va_base; /* MPU virtual address */ dma_addr_t fb_pa_base; /* Bus physical address */ unsigned long fb_size_in_byte; unsigned long layer_enable; MTK_FB_FORMAT layer_formatHW_OVERLAY_COUNT; unsigned int layer_config_dirty; int xscale, yscale, mirror; /* transformations. rotate is stored in fb_info-var */ u32 pseudo_palette17; struct fb_info *fb_info; /* Linux fbdev framework data */ struct device *dev;六、 uBoot阶段Mt6573_board.c中，board_init函数执行硬件先期初始化工作，它调用mt65xx_disp_init函数(Mt6573_disp_drv.c)。board_initmt65xx_disp_initDISP_Initdisp_drv_init_contextDISP_DetectDevicedisp_drv_get_lcm_driverlcm_driver_list disp_drv_init_contextDISP_GetDriverDPI / DISP_GetDriverDBI / DISP_GetDriverDSIDISP_GetDriverDPI (mt6573_disp_drv_dpi.c)DPI_DISP_DRV. dpi_initinit_dpiDPI_Init （Mt6573_dpi_drv.c）DISP_GetDriverDBI (mt6573_disp_drv_dbi.c)DBI_DISP_DRV. dbi_initinit_lcdLCD_xxx（Mt6573_lcd_drv.c）DISP_GetDriverDSI (mt6573_disp_drv_dsi.c)DSI_DISP_DRV. dsi_initinit_lcd，init_dsiDSI_Init（Mt6573_dsi_drv.c）DISP_InitLCD_Init (Mt6573_lcd_drv.c)DISP_UpdateScreenLCD_StartTransfer (Mt6573_lcd_drv.c)七、 背光控制Cust_leds.c中定义了cust_mt65xx_led类型的数组cust_led_list，列出了平台的所有led设备，包括不同颜色的led灯，轨迹球、键盘、按键、LCD等的背光灯。不同led设备可以有各自不同的背光控制方式，比如PWM（脉冲宽度调制）方式，GPIO方式，PMIC方式，用户自定义方式等。如下所示：static struct cust_mt65xx_led cust_led_listMT65XX_LED_TYPE_TOTAL = red, MT65XX_LED_MODE_PWM, PWM3,green, MT65XX_LED_MODE_PWM, PWM2,blue, MT65XX_LED_MODE_PWM, PWM1,jogball-backlight, MT65XX_LED_MODE_NONE, -1,keyboard-backlight, MT65XX_LED_MODE_NONE, -1,button-backlight, MT65XX_LED_MODE_PWM, PWM7,lcd-backlight, MT65XX_LED_MODE_CUST, (int)Cust_SetBacklight,;这个数组通过get_cust_led_list函数被mt65xx_leds_probe调用，传递给mt65xx_leds_driver，并且mt65xx_leds_probe 将数组中的设