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diff --git a/Documentation/fb/sh7760fb.rst b/Documentation/fb/sh7760fb.rst new file mode 100644 index 000000000..c3266485f --- /dev/null +++ b/Documentation/fb/sh7760fb.rst @@ -0,0 +1,130 @@ +================================================ +SH7760/SH7763 integrated LCDC Framebuffer driver +================================================ + +0. Overview +----------- +The SH7760/SH7763 have an integrated LCD Display controller (LCDC) which +supports (in theory) resolutions ranging from 1x1 to 1024x1024, +with color depths ranging from 1 to 16 bits, on STN, DSTN and TFT Panels. + +Caveats: + +* Framebuffer memory must be a large chunk allocated at the top + of Area3 (HW requirement). Because of this requirement you should NOT + make the driver a module since at runtime it may become impossible to + get a large enough contiguous chunk of memory. + +* The driver does not support changing resolution while loaded + (displays aren't hotpluggable anyway) + +* Heavy flickering may be observed + a) if you're using 15/16bit color modes at >= 640x480 px resolutions, + b) during PCMCIA (or any other slow bus) activity. + +* Rotation works only 90degress clockwise, and only if horizontal + resolution is <= 320 pixels. + +Files: + - drivers/video/sh7760fb.c + - include/asm-sh/sh7760fb.h + - Documentation/fb/sh7760fb.rst + +1. Platform setup +----------------- +SH7760: + Video data is fetched via the DMABRG DMA engine, so you have to + configure the SH DMAC for DMABRG mode (write 0x94808080 to the + DMARSRA register somewhere at boot). + + PFC registers PCCR and PCDR must be set to peripheral mode. + (write zeros to both). + +The driver does NOT do the above for you since board setup is, well, job +of the board setup code. + +2. Panel definitions +-------------------- +The LCDC must explicitly be told about the type of LCD panel +attached. Data must be wrapped in a "struct sh7760fb_platdata" and +passed to the driver as platform_data. + +Suggest you take a closer look at the SH7760 Manual, Section 30. +(http://documentation.renesas.com/eng/products/mpumcu/e602291_sh7760.pdf) + +The following code illustrates what needs to be done to +get the framebuffer working on a 640x480 TFT:: + + #include <linux/fb.h> + #include <asm/sh7760fb.h> + + /* + * NEC NL6440bc26-01 640x480 TFT + * dotclock 25175 kHz + * Xres 640 Yres 480 + * Htotal 800 Vtotal 525 + * HsynStart 656 VsynStart 490 + * HsynLenn 30 VsynLenn 2 + * + * The linux framebuffer layer does not use the syncstart/synclen + * values but right/left/upper/lower margin values. The comments + * for the x_margin explain how to calculate those from given + * panel sync timings. + */ + static struct fb_videomode nl6448bc26 = { + .name = "NL6448BC26", + .refresh = 60, + .xres = 640, + .yres = 480, + .pixclock = 39683, /* in picoseconds! */ + .hsync_len = 30, + .vsync_len = 2, + .left_margin = 114, /* HTOT - (HSYNSLEN + HSYNSTART) */ + .right_margin = 16, /* HSYNSTART - XRES */ + .upper_margin = 33, /* VTOT - (VSYNLEN + VSYNSTART) */ + .lower_margin = 10, /* VSYNSTART - YRES */ + .sync = FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT, + .vmode = FB_VMODE_NONINTERLACED, + .flag = 0, + }; + + static struct sh7760fb_platdata sh7760fb_nl6448 = { + .def_mode = &nl6448bc26, + .ldmtr = LDMTR_TFT_COLOR_16, /* 16bit TFT panel */ + .lddfr = LDDFR_8BPP, /* we want 8bit output */ + .ldpmmr = 0x0070, + .ldpspr = 0x0500, + .ldaclnr = 0, + .ldickr = LDICKR_CLKSRC(LCDC_CLKSRC_EXTERNAL) | + LDICKR_CLKDIV(1), + .rotate = 0, + .novsync = 1, + .blank = NULL, + }; + + /* SH7760: + * 0xFE300800: 256 * 4byte xRGB palette ram + * 0xFE300C00: 42 bytes ctrl registers + */ + static struct resource sh7760_lcdc_res[] = { + [0] = { + .start = 0xFE300800, + .end = 0xFE300CFF, + .flags = IORESOURCE_MEM, + }, + [1] = { + .start = 65, + .end = 65, + .flags = IORESOURCE_IRQ, + }, + }; + + static struct platform_device sh7760_lcdc_dev = { + .dev = { + .platform_data = &sh7760fb_nl6448, + }, + .name = "sh7760-lcdc", + .id = -1, + .resource = sh7760_lcdc_res, + .num_resources = ARRAY_SIZE(sh7760_lcdc_res), + }; |