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