开发板：tiny4412SDK + S702 + 4GB Flash
要移植的内核版本：Linux-4.4.0 （支持device tree）
u-boot版本：友善之臂自带的 U-Boot 2010.12
busybox版本：busybox 1.25
参考：tiny4412LCD驱动加字符显示
1、背光
友善之臂的该款LCD采用了一线触控技术，包括背光控制也集成在一线触控之中，关于背光的控制，在前一篇文章中已经提及，本文重点在于LCD驱动。
2、LCD接口
3、图像的构成
4、颜色的量化(颜色<—–>数字)
颜色一般采用RGB标准,通过对红（R）、绿（GREEN），蓝（B）三个颜色以及相互叠加获取各种不同的颜色
5、显示图像与LCD时序
6、Exyons 4412 display 控制器
7、Exyons 4412 display 控制器配置
一、设备树
&pinctrl_0 {
lcd_demo: 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>;
};
};
lcd_demo@11C00000{
compatible = "tiny4412,lcd_demo";
reg = <0x11C00000 0x20c0 0x10010210 0x08 0x10023c80 0x04 0x1003c000 0x1000>;
pinctrl-names = "default";
pinctrl-0 = <&lcd_demo>;
clocks = <&clock CLK_FIMD0 &clock CLK_ACLK160>;
clock-names = "fimd0","aclk160";
};
二、驱动代码
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/div64.h>
#include <asm/mach/map.h>
#include <linux/fb.h>
#include <asm/types.h>
#define VIDCON0 0x00
#define VIDCON1 0x04
#define VIDTCON0 0x10
#define VIDTCON1 0x14
#define VIDTCON2 0x18
#define WINCON0 0x20
#define VIDOSD0C 0x48
#define SHADOWCON 0x34
#define WINCHMAP2 0x3c
#define VIDOSD0A 0x40
#define VIDOSD0B 0x44
#define VIDW00ADD0B0 0xA0
#define VIDW00ADD1B0 0xD0
#define CLK_SRC_LCD0 0x234
#define CLK_SRC_MASK_LCD 0x334
#define CLK_DIV_LCD 0x534
#define CLK_GATE_IP_LCD 0x934
#define LCDBLK_CFG 0x00
#define LCDBLK_CFG2 0x04
static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
unsigned int green, unsigned int blue,
unsigned int transp, struct fb_info *info);
static struct fb_ops s3c_lcdfb_ops =
{
.owner = THIS_MODULE,
.fb_setcolreg = s3c_lcdfb_setcolreg,
.fb_fillrect = cfb_fillrect,
.fb_copyarea = cfb_copyarea,
.fb_imageblit = cfb_imageblit,
};
static struct fb_info *s3c_lcd;
static volatile void __iomem *lcd_regs_base;
static volatile void __iomem *clk_regs_base;
static volatile void __iomem *lcdblk_regs_base;
static volatile void __iomem *lcd0_configuration;
static u32 pseudo_palette[16];
static struct resource *res1, *res2, *res3, *res4;
/* from pxafb.c */
static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
chan &= 0xffff;
chan >>= 16 - bf->length;
return chan << bf->offset;
}
static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
unsigned int green, unsigned int blue,
unsigned int transp, struct fb_info *info)
{
unsigned int val;
if (regno > 16)
{ return 1; }
/* 用red,green,blue三原色构造出val */
val = chan_to_field(red, &info->var.red);
val |= chan_to_field(green, &info->var.green);
val |= chan_to_field(blue, &info->var.blue);
//((u32 *)(info->pseudo_palette))[regno] = val;
pseudo_palette[regno] = val;
return 0;
}
static int lcd_probe(struct platform_device *pdev)
{
int ret;
unsigned int temp;
/* 1. 分配一个fb_info */
s3c_lcd = framebuffer_alloc(0, NULL);
/* 2. 设置 */
/* 2.1 设置 fix 固定的参数 */
strcpy(s3c_lcd->fix.id, "mylcd");
s3c_lcd->fix.smem_len = 480 * 800 * 16 / 8; //显存的长度
s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS; //类型
s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; //TFT 真彩色
s3c_lcd->fix.line_length = 800 * 2; //一行的长度
/* 2.2 设置 var 可变的参数 */
s3c_lcd->var.xres = 800; //x方向分辨率
s3c_lcd->var.yres = 480; //y方向分辨率
s3c_lcd->var.xres_virtual = 800; //x方向虚拟分辨率
s3c_lcd->var.yres_virtual = 480; //y方向虚拟分辨率
s3c_lcd->var.bits_per_pixel = 16; //每个像素占的bit
/* RGB:565 */
s3c_lcd->var.red.offset = 11; //红
s3c_lcd->var.red.length = 5;
s3c_lcd->var.green.offset = 5; //绿
s3c_lcd->var.green.length = 6;
s3c_lcd->var.blue.offset = 0; //蓝
s3c_lcd->var.blue.length = 5;
s3c_lcd->var.activate = FB_ACTIVATE_NOW;
/* 2.3 设置操作函数 */
s3c_lcd->fbops = &s3c_lcdfb_ops;
/* 2.4 其他的设置 */
s3c_lcd->pseudo_palette = pseudo_palette; //调色板
//s3c_lcd->screen_base = ; //显存的虚拟地址,分配显存时填充
s3c_lcd->screen_size = 480 * 800 * 16 / 8; //显存大小
/* 3. 硬件相关的操作 */
/* 3.1 配置GPIO用于LCD */
//设备树中使用"default"
/* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
//寄存器映射
res1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res1 == NULL)
{
printk("platform_get_resource error\n");
return -EINVAL;
}
lcd_regs_base = devm_ioremap_resource(&pdev->dev, res1);
if (lcd_regs_base == NULL)
{
printk("devm_ioremap_resource error\n");
return -EINVAL;
}
res2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
if (res2 == NULL)
{
printk("platform_get_resource error\n");
return -EINVAL;
}
lcdblk_regs_base = devm_ioremap_resource(&pdev->dev, res2);
if (lcdblk_regs_base == NULL)
{
printk("devm_ioremap_resource error\n");
return -EINVAL;
}
res3 = platform_get_resource(pdev, IORESOURCE_MEM, 2);
if (res3 == NULL)
{
printk("platform_get_resource error\n");
return -EINVAL;
}
lcd0_configuration = ioremap(res3->start, 0x04);
*lcd0_configuration = 0x07;
res4 = platform_get_resource(pdev, IORESOURCE_MEM, 3);
if (res4 == NULL)
{
printk("platform_get_resource error\n");
return -EINVAL;
}
clk_regs_base = ioremap(res4->start, 0x1000);
if (clk_regs_base == NULL)
{
printk("devm_ioremap_resource error\n");
return -EINVAL;
}
//使能时钟
//时钟源选择 0110 SCLKMPLL_USER_T 800M
temp = readl(clk_regs_base + CLK_SRC_LCD0);
temp &= ~0x0f;
temp |= 0x06;
writel(temp, clk_regs_base + CLK_SRC_LCD0);
//FIMD0_MASK
temp = readl(clk_regs_base + CLK_SRC_MASK_LCD);
temp |= 0x01;
writel(temp, clk_regs_base + CLK_SRC_MASK_LCD);
//SCLK_FIMD0 = MOUTFIMD0/(FIMD0_RATIO + 1),分频 1/1
temp = readl(clk_regs_base + CLK_DIV_LCD);
temp &= ~0x0f;
writel(temp, clk_regs_base + CLK_DIV_LCD);
//CLK_FIMD0 Pass
temp = readl(clk_regs_base + CLK_GATE_IP_LCD);
temp |= 0x01;
writel(temp, clk_regs_base + CLK_GATE_IP_LCD);
//FIMDBYPASS_LBLK0 FIMD Bypass
temp = readl(lcdblk_regs_base + LCDBLK_CFG);
temp |= 1 << 1;
writel(temp, lcdblk_regs_base + LCDBLK_CFG);
temp = readl(lcdblk_regs_base + LCDBLK_CFG2);
temp |= 1 << 0;
writel(temp, lcdblk_regs_base + LCDBLK_CFG2);
mdelay(1000);
//分频 800/(23 +1 ) == 33M
temp = readl(lcd_regs_base + VIDCON0);
temp |= (23 << 6);
writel(temp, lcd_regs_base + VIDCON0);
/*
* VIDTCON1:
* [5]:IVSYNC ===> 1 : Inverted(反转)
* [6]:IHSYNC ===> 1 : Inverted(反转)
* [7]:IVCLK ===> 1 : Fetches video data at VCLK rising edge (下降沿触发)
* [10:9]:FIXVCLK ====> 01 : VCLK running
*/
temp = readl(lcd_regs_base + VIDCON1);
temp |= (1 << 9) | (1 << 7) | (1 << 5) | (1 << 6);
writel(temp, lcd_regs_base + VIDCON1);
/*
* VIDTCON0:
* [23:16]: VBPD + 1 <------> tvpw (1 - 20) 13
* [15:8] : VFPD + 1 <------> tvfp 22
* [7:0] : VSPW + 1 <------> tvb - tvpw = 23 - 13 = 10
*/
temp = readl(lcd_regs_base + VIDTCON0);
temp |= (12 << 16) | (21 << 8) | (9);
writel(temp, lcd_regs_base + VIDTCON0);
/*
* VIDTCON1:
* [23:16]: HBPD + 1 <------> thpw (1 - 40) 36
* [15:8] : HFPD + 1 <------> thfp 210
* [7:0] : HSPW + 1 <------> thb - thpw = 46 - 36 = 10
*/
temp = readl(lcd_regs_base + VIDTCON1);
temp |= (35 << 16) | (209 << 8) | (9);
writel(temp, lcd_regs_base + VIDTCON1);
/*
* HOZVAL = (Horizontal display size) - 1 and LINEVAL = (Vertical display size) - 1.
* Horizontal(水平) display size : 800
* Vertical(垂直) display size : 480
*/
temp = (479 << 11) | 799;
writel(temp, lcd_regs_base + VIDTCON2);
/*
* WINCON0:
* [16]:Specifies Half-Word swap control bit. 1 = Enables swap P1779 低位像素存放在低字节
* [5:2]: Selects Bits Per Pixel (BPP) mode for Window image : 0101 ===> 16BPP RGB565
* [1]:Enables/disables video output 1 = Enables
*/
temp = readl(lcd_regs_base + WINCON0);
temp |= (1 << 16) | (5 << 2) | 1;
writel(temp, lcd_regs_base + WINCON0);
temp = readl(lcd_regs_base + SHADOWCON);
writel(temp | 0x01, lcd_regs_base + SHADOWCON);
//p1769
temp = readl(lcd_regs_base + WINCHMAP2);
temp &= ~(7 << 16);
temp |= 1 << 16;
temp &= ~7;
temp |= 1;
writel(temp, lcd_regs_base + WINCHMAP2);
/*
* bit0-10 : 指定OSD图像左上像素的垂直屏幕坐标
* bit11-21: 指定OSD图像左上像素的水平屏幕坐标
*/
writel(0, lcd_regs_base + VIDOSD0A);
/*
* bit0-10 : 指定OSD图像右下像素的垂直屏幕坐标
* bit11-21: 指定OSD图像右下像素的水平屏幕坐标
*/
writel((799 << 11) | 479, lcd_regs_base + VIDOSD0B);
//Window Size For example, Height ? Width (number of word)
temp = 480 * 800 >> 1;
writel(temp, lcd_regs_base + VIDOSD0C);
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
// s3c_lcd->screen_base 显存虚拟地址
// s3c_lcd->fix.smem_len 显存大小，前面计算的
// s3c_lcd->fix.smem_start 显存物理地址
s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, (dma_addr_t *)&s3c_lcd->fix.smem_start, GFP_KERNEL);
//显存起始地址
writel(s3c_lcd->fix.smem_start, lcd_regs_base + VIDW00ADD0B0);
//显存结束地址
writel(s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len, lcd_regs_base + VIDW00ADD1B0);
//Enables video output and logic immediately
temp = readl(lcd_regs_base + VIDCON0);
writel(temp | 0x03, lcd_regs_base + VIDCON0);
/* 4. 注册 */
ret = register_framebuffer(s3c_lcd);
return ret;
}
static int lcd_remove(struct platform_device *pdev)
{
printk("%s enter.\n", __func__);
unregister_framebuffer(s3c_lcd);
dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);
framebuffer_release(s3c_lcd);
iounmap(lcd0_configuration);
iounmap(clk_regs_base);
return 0;
}
static const struct of_device_id lcd_dt_ids[] =
{
{ .compatible = "tiny4412,lcd_demo", },
{},
};
MODULE_DEVICE_TABLE(of, lcd_dt_ids);
static struct platform_driver lcd_driver =
{
.driver = {
.name = "lcd_demo",
.of_match_table = of_match_ptr(lcd_dt_ids),
},
.probe = lcd_probe,
.remove = lcd_remove,
};
static int lcd_init(void)
{
int ret;
printk("enter %s\n", __func__);
ret = platform_driver_register(&lcd_driver);
if (ret)
{
printk(KERN_ERR "pwm demo: probe faipwm: %d\n", ret);
}
return ret;
}
static void lcd_exit(void)
{
printk("enter %s\n", __func__);
platform_driver_unregister(&lcd_driver);
}
module_init(lcd_init);
module_exit(lcd_exit);
MODULE_LICENSE("GPL");