UM0851 datasheet(195/245 Pages) STMICROELECTRONICS

195 / 245 page

UM0851

Audio/video drivers

Doc ID 16604 Rev 2

195/245

void (*fb_fillrect)(struct fb_info *info, const struct fb_fillrect *rect);

/*Accelerated method to copy a rectangular area from one screen region to another

void (*fb_copyarea)(struct fb_info *info,const struct fb_copyarea *region);

/* Ioctl interface to support device-specific commands */

int (*fb_ioctl)(struct fb_info *info, unsigned int cmd, unsigned long arg);

/* ... */

};

Framebuffer sources

/dev/fb0 also allows several IOCTLs on it, by which a lot of information about the hardware

can be queried and set. The color map handling works via IOCTLs, too. Look into

<linux/fb.h> for more information on what IOCTLs exist and on which data structures they

work. Here's just a brief overview:

8.1.4

How to support a new CLCD panel

There is a separate application note (AN2641) which discusses this in detail. However in

short, for a new CLCD panel at least following needs to be checked in the device driver:

Step 1: CLCD panel information should be defined in platform/amba device of arch.

Step 2: CLCD panel should be supported by ARM PL110 Controller. The types of panels

supported by controller are listed in the corresponding SPEAr user manual).

8.1.5

CLCD driver usage

A framebuffer device is a memory device like /dev/mem and it has the same features. You

can read it, write it, seek to some location in it and mmap () it (the main usage). The

difference is just that the memory that appears in the special file is not the whole memory,

but the frame buffer of the video hardware.

Data structures for using Framebuffer

The following three structures must be understood, because they are needed for any user

application that uses framebuffer.

Variable information pertaining to the video card is held in struct fb_var_screeninfo.

This structure contains fields such as the X-resolution, Y-resolution, bits required to

Table 50.

Framebuffer information in source code

Directory or resource

Purpose

drivers/video/

The frame buffer core layer and low-level frame buffer driversreside in this

UM0851 Datasheet(PDF) 195 Page - STMicroelectronics