设备树学习之（十二）LCD驱动

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

1)Tiny 4412 使用的lcd接口为LCD1
2)图片数据信号接口
- B[0:7] : 蓝色数据信号线
- G[0:7] : 绿色数据信号线
- R[0:7] : 红色数据信号线
3)时序信号接口
- DEN 数据允许信号
- VSYNC 垂直同步信号
- HSYNC 水平同步信号
- VLCK LCD时钟信号
4)一线触控
- XEINT10_OUT

设备树学习之（十二）LCD驱动

3、图像的构成

帧：一幅图像被称为一帧,每帧有多行组成，每行有多个像素点组成
像素：
- 1)显示的最小单位
- 2)由若干位的颜色数据来构成,像素越高，则一个像素点所需要的颜色数据越多，能够显示的颜色更广
- 3)一个像素点构成的颜色位数称为像素深度，单位为1BPP 常见的有16BPP/24BPP

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

1）通过对颜色的编码来对颜色进行量化（即转换成数字量，RGB是一种编码方式）
2）每种颜色根据RGB格式不同，每种颜色的量化位不相同
3) 常见的RGB格式有RGB565/RGB888
- RGB565: red :5 green : 6 blue:5
- RGB888: red :8 green : 8 blue:8

5、显示图像与LCD时序

1)使用HSYNC信号来控制一行的显示
2)使用VSYNC信号来控制一帧的显示
3)使用VCLK信号来控制一个像素的显示
4)使用VDEN信号来控制数据的输出

6、Exyons 4412 display 控制器

1)alpha,alpha操作用于实现图形渐变效果，以及半透明效果
- 0xfff == 全透明
- 0x0 == 不透明
2)colorkey,colorkey操作在融合两个窗口时过虑掉其中一个窗口的某一种特定颜色
3)HOZVAL与LINEVAL
- HOZVAL = (Horizontal display size) - 1
- LINEVAL = (Vertical display size) - 1
4)LCD时序图
notes:
.Using the display controller data, you can select one of the above data paths by setting LCDBLK_CFG Register(0x1001_0210). For more information, refer to the “System Others” manual

7、Exyons 4412 display 控制器配置

1)gpio配置,查看原理图 ,获取LCD接口的对应的gpio
- LCD_HSYNC:GPF0_0
- LCD_VSYNC:GPF0_1
- LCD_VDEV: GPF0_2
- LCD_VCLK: GPF0_3
- VD[23:0]:GPF1_0 - GPF1_5 / GPF2_0 - GPF2_7 / GPF3_0 - GPF3_3
2)时钟配置
- (1)查看Exyons 4412 手册获取LCD时钟源
  LCD 时钟源为SCLKmpll_user_t:800Mhz
- (2)配置相关的寄存器得到LCD所需要的时钟 (见07lcd_clock)
3)系统配置
LCDBLK_CFG : 配置成FIMD接口

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");

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设备树学习之（十二）LCD驱动

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