【TINY4412】LINUX移植笔记：（27）设备树LCD驱动
【TINY4412】LINUX移植笔记：（27）设备树 LCD驱动
宿主机 ： 虚拟机 Ubuntu 16.04 LTS / X64
目标板[底板]： Tiny4412SDK - 1506
目标板[核心板]： Tiny4412 - 1412
LINUX内核： 4.12.0
交叉编译器： arm-none-linux-gnueabi-gcc（gcc version 4.8.3 20140320）
日期： 2017-9-11 21:06:56
作者： SY
简介
开发板的液晶屏型号S702，电容触摸屏，分辨率：800X480
根据三星手册41 Display Controller章节，LCD接口支持三种接口， RGB-interface indirect-i80 interface and YUV interface for write-back
使用RGB888接口，包含24位并行数据总线。
设备树
lcd_s702@11C00000 {
compatible = "tiny4412, lcd_s702";
reg = <0x11C00000 0x20c0 0x10010210 0x08 0x10023c80 0x04 0x1003c000 0x1000>;
pinctrl-names = "default";
pinctrl-0 = <&lcd_s702>;
clocks = <&clock CLK_FIMD0 &clock CLK_ACLK160>;
clock-names = "fimd0","aclk160";
};
&pinctrl_0 {
lcd_s702:lcd {
samsung,pins = "gpf0-0", "gpf0-1", "gpf0-2", "gpf0-3", "gpf0-4",
"gpf0-5", "gpf0-6","gpf0-7", "gpf1-0", "gpf1-1",
"gpf1-2", "gpf1-3", "gpf1-4", "gpf1-5", "gpf1-6",
"gpf1-7", "gpf2-0", "gpf2-1", "gpf2-2", "gpf2-3",
"gpf2-4", "gpf2-5", "gpf2-6","gpf2-7", "gpf3-0",
"gpf3-1", "gpf3-2", "gpf3-3";
samsung,pin-function = <2>;
samsung,pin-pud = <0>;
samsung,pin-drv = <0>;
};
};menuconfig
Device Drivers --->
Graphics support --->
Console display driver support --->
<*> Framebuffer Console support
移植
#include makefile
# Linux modules compile
# Author : SY
# Time : 2017-8-8 21:30:31
#############################################################################
TARGET := tiny4412_fb
obj-m := $(TARGET).o
CROSS := arm-none-linux-gnueabi-
KDIR := /opt/fs/rootfs/rootfs/lib/modules/4.12.0+/build
PWD := $(shell pwd)
INSTALL_DIR := /opt/fs/rootfs/rootfs
all:
$(MAKE) -C $(KDIR) M=$(PWD)
install:
$(MAKE) -C $(KDIR) M=$(PWD) modules_install INSTALL_MOD_PATH=$(INSTALL_DIR)
chmod 755 $(TARGET).ko
cp $(TARGET).ko /opt/fs/rootfs/rootfs/opt/app
clean:
rm -rf *.o *.ko *.mod.c *.temp_versions *.symvers *.order .built* .tmp* .$(TARGET)*一开始烧录后测试，红色显示蓝色，绿色显示黑色，蓝色显示红色。最后发现原因是：
temp = readl(lcd_regs_base + WINCON0);
temp &= ~(0xf << 2);
temp |= (1 << 15) | (0xd << 2) | 1;
writel(temp, lcd_regs_base + WINCON0);原来设置为 1 << 16 ，应该修改为 1 << 15 ，代表的含义：
15: Specifies Word swap control bit.
16: Specifies Half-Word swap control bit.如果使用 16 位色，需要设置为 16 ；
如果使用 32 位色，需要设置为 15 ；
APP
/*
* lcd_fb driver for tiny4412
*
* Copyright (c) 2017
* Author: SY <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
*/
#include
#include \n" );
}
#endif
/*
bool esc = false;
static void sigint_handler(int dunno)
{
switch (dunno) {
case SIGINT:
esc = true;
printf("< Ctrl+C > Press.\n");
break;
default:
break;
}
}
*/
#define RED_COLOR565 0xFF0000
#define GREEN_COLOR565 0x00FF00
#define BLUE_COLOR565 0x0000FF
int main(int argc, char **argv)
{
int fb = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screen_size = 0;
uint32_t *fbp = NULL;
int x = 0, y = 0;
fb = open("/dev/fb0", O_RDWR);
if(!fb) {
printf("open /dev/fb0 return error\n");
return -1;
}
if(ioctl(fb, FBIOGET_FSCREENINFO, &finfo)) {
printf("get fb fixed infomation return error\n");
return -1;
}
if(ioctl(fb, FBIOGET_VSCREENINFO, &vinfo)) {
printf("get fb variable infomation return error\n");
return -1;
}
screen_size = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("%d-%d, %dbpp, screen_size = %ld\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel, screen_size);
fbp = (uint32_t *)mmap(0, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
if(fbp < 0) {
printf("mmap return error\n");
return -1;
}
{
// Red Screen
printf("Red Screen\n");
for(y = 0; y < vinfo.yres/3; y++)
{
for(x = 0; x < vinfo.xres ; x++)
{
*(fbp + y * vinfo.xres + x) = RED_COLOR565;
}
}
// Green Screen
printf("Green Screen\n");
for(y = vinfo.yres/3; y < (vinfo.yres*2)/3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp + y * vinfo.xres + x) =GREEN_COLOR565;
}
}
// Blue Screen
printf("Blue Screen\n");
for(y = (vinfo.yres*2)/3; y < vinfo.yres; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp + y * vinfo.xres + x) = BLUE_COLOR565;
}
}
}
munmap(fbp, screen_size);
close(fb);
return 0;
}makefile
# Linux modules compile
# Author : SY
# Time : 2017-8-10 22:29:24
#############################################################################
CC = arm-none-linux-gnueabi-gcc
CFLAGS = -Wall -std=gnu99 -pthread
TARGET = lcd_fb
OBJS = $(TARGET).o
INSTALL_PATH = /opt/fs/rootfs/rootfs/tmp/
$(TARGET) : $(OBJS)
$(CC) $(CFLAGS) -o $@ $<
install:
chmod 755 $(TARGET)
cp $(TARGET) $(INSTALL_PATH)
clean:
rm -rf *.o $(TARGET) 测试
将 lcd 驱动编译进内核，可以正常加载 4 只小企鹅，但是屏幕在几秒之后会自动熄灭，再向 dev/fb0 写入数据，屏幕不显示，以后待解决。
如果将驱动编译为模块，放在 etc/init.d/rcS
# load lcd
/opt/app/backlight 127
insmod /opt/app/tiny4412_fb.ko上面表示先打开 lcd 背光，再加载 lcd 模块。
进入 etc/inittab ，输入：
::sysinit:/etc/init.d/rcS
::respawn:-/bin/sh
tty0::askfirst:-/bin/sh
::ctrlaltdel:/bin/umount -a -r其中最重要的是第三段， tty0 设备表示 lcd 输出，askfirst 会询问用户激活命令行，/bin/sh 表示命令行脚本。 这样，重新上电后 lcd 默认加载命令行，插上鼠标后：
参考
Linux驱动：LCD驱动框架分析
设备树学习之（十二）LCD驱动