学习笔记 --- LINUX LCD显示原理与驱动分析
在分析驱动之前,先来分析下显示原理,这里以S3C2440为例,看下这个芯片的LCD控制器时序图:
VSYNC :帧数据脉冲,脉冲换屏,表示一屏数据开始
HSYNC :行数据脉冲,脉冲换行,表示一行数据开始
LEND :行结束脉冲,脉冲表示一行结束
VDEN :数据使能,表示VD可以发数据
VCLK :基准时钟,脉冲送往数据线送一次数据
VD :数据
这些都是硬件管脚信号线,从图中可以看出一行中有效数据是HOZVAL+1个像素,(HSPW+1)+(HBPD+1)是屏幕左边黑框的像素,HFPD+1是屏幕右边黑框的像素,一般设置为左边等于右边,上边等于下边,iphone手机有很明显的黑框。那么上边就是(VSPW+1)+(VBPD+1)行,下边就是VFPD+1行,中间有效数据是LINEVAL+1行。假设LCD为240X320那么时序对应的显示图像就是(截图自韦东山老师):
外面的大框表示LCD黑框,里面表示真正显示的有效数据240X320。接下来说下显示16bpp图像的原理:
16bpp图像意思就是一个像素要用16个位来表示,那么就有2的16次方种颜色,一个像素16位,占2个字节,一屏240X320像素,那么一屏数据占240X320X2个字节,所以显存至少要这么大的空间。一个像素由红绿蓝三原色构成,所以这两个字节包含了红绿蓝三种颜色的信息,他们的占用bit数的比率为5:6:5,也可以是5:5:5,先只说5:6:5格式的,5+6+5=16bit,高位到低位分别表示5位红色,6位绿色,5位蓝色组成了一个两字节数据放在显存区里面,然后LCD控制器将其搬到LCD上显示出来,他们在显存里面的存放有两种方式:
一般选择下面这种方式,先放低16位,再放高16位,S3C2440默认是小端存储,所以这样低位对应低地址,刚好可以对应起来;那么从显存传输到LCD时数据线[0-23]传输的格式如何?
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分析了原理,下面看驱动,LCD的驱动核心在内核fbmem.c里面,分析驱动从入口开始:
-
static int __init fbmem_init(void)
-
{
-
proc_create("fb", 0, NULL, &fb_proc_fops);
-
if (register_chrdev(FB_MAJOR,"fb",&fb_fops)) //注册为字符设备驱动,主设备号为FB_MAJOR
-
printk("unable to get major %d for fb devs\n", FB_MAJOR);
-
fb_class = class_create(THIS_MODULE, "graphics"); //创建类
-
if (IS_ERR(fb_class)) {
-
printk(KERN_WARNING "Unable to create fb class; errno = %ld\n", PTR_ERR(fb_class));
-
fb_class = NULL;
-
}
-
return 0;
-
}
可以知道LCD驱动也就是一个字符设备驱动而已,这个框架已经熟悉了,再看下fops部分:
-
static const struct file_operations fb_fops = {
-
.owner = THIS_MODULE,
-
.read = fb_read,
-
.write = fb_write,
-
.unlocked_ioctl = fb_ioctl,
-
#ifdef CONFIG_COMPAT
-
.compat_ioctl = fb_compat_ioctl,
-
#endif
-
.mmap = fb_mmap,
-
.open = fb_open,
-
.release = fb_release,
-
#ifdef HAVE_ARCH_FB_UNMAPPED_AREA
-
.get_unmapped_area = get_fb_unmapped_area,
-
#endif
-
#ifdef CONFIG_FB_DEFERRED_IO
-
.fsync = fb_deferred_io_fsync,
-
#endif
-
};
这里有读写控制,打开等操作,我们首先肯定是打开,先看打开:
-
static int
-
fb_open(struct inode *inode, struct file *file)
-
__acquires(&info->lock)
-
__releases(&info->lock)
-
{
-
int fbidx = iminor(inode);
-
struct fb_info *info;
-
int res = 0;
-
if (fbidx >= FB_MAX)
-
return -ENODEV;
-
info = registered_fb[fbidx]; //这里从数组传入一个info
-
if (!info)
-
request_module("fb%d", fbidx);
-
info = registered_fb[fbidx];
-
if (!info)
-
return -ENODEV;
-
mutex_lock(&info->lock);
-
if (!try_module_get(info->fbops->owner)) {
-
res = -ENODEV;
-
goto out;
-
}
-
file->private_data = info;
-
if (info->fbops->fb_open) {
-
res = info->fbops->fb_open(info,1); //调用info的打开函数
-
if (res)
-
module_put(info->fbops->owner);
-
}
-
#ifdef CONFIG_FB_DEFERRED_IO
-
if (info->fbdefio)
-
fb_deferred_io_open(info, inode, file);
-
#endif
-
out:
-
mutex_unlock(&info->lock);
-
return res;
-
}
可以知道他首先从registered_fb获取一个info,再调用info的open,再看read:
-
static ssize_t
-
fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
-
{
-
unsigned long p = *ppos;
-
struct inode *inode = file->f_path.dentry->d_inode;
-
int fbidx = iminor(inode);
-
struct fb_info *info = registered_fb[fbidx];//熟悉吧,我们又看到这个数组了
-
u32 *buffer, *dst;
-
u32 __iomem *src;
-
int c, i, cnt = 0, err = 0;
-
unsigned long total_size;
-
if (!info || ! info->screen_base)//跟那个数组有关
-
return -ENODEV;
-
if (info->state != FBINFO_STATE_RUNNING)//跟那个数组有关
-
return -EPERM;
-
if (info->fbops->fb_read)//如果操作函数集里定义了read函数,就调用,否则就算了
-
return info->fbops->fb_read(info, buf, count, ppos);
-
total_size = info->screen_size;//跟那个数组有关
-
if (total_size == 0)
-
total_size = info->fix.smem_len;//跟那个数组有关
-
if (p >= total_size)
-
return 0;
-
if (count >= total_size)
-
count = total_size;
-
if (count + p > total_size)
-
count = total_size - p;
-
buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,//开辟一个buffer
-
GFP_KERNEL);
-
if (!buffer)
-
return -ENOMEM;
-
src = (u32 __iomem *) (info->screen_base + p);//显存基地址也在里面
-
if (info->fbops->fb_sync)
-
info->fbops->fb_sync(info);
-
while (count) {
-
c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
-
dst = buffer;//目的指针指向一个buffer(我们在上面开辟的)
-
for (i = c >> 2; i--; )
-
*dst++ = fb_readl(src++);//从基地址读取数据放进buffer中
-
if (c & 3) {
-
u8 *dst8 = (u8 *) dst;
-
u8 __iomem *src8 = (u8 __iomem *) src;
-
for (i = c & 3; i--;)
-
*dst8++ = fb_readb(src8++);
-
src = (u32 __iomem *) src8;
-
}
-
if (copy_to_user(buf, buffer, c))//将buffer中的数据拷贝到用户空间,这样在用户空间调用read函数时就把显存内容读出来了
-
{
-
err = -EFAULT;
-
break;
-
}
-
*ppos += c;
-
buf += c;
-
cnt += c;
-
count -= c;
-
}
-
kfree(buffer);
-
return (err) ? err : cnt;
-
}
读函数就是读info里面显存存放的数据,可以知道这个info很重要,那么registered_fb里面放的info,怎么来的?
-
int
-
register_framebuffer(struct fb_info *fb_info)
-
{
-
int i;
-
struct fb_event event;
-
struct fb_videomode mode;
-
if (num_registered_fb == FB_MAX)
-
return -ENXIO;
-
if (fb_check_foreignness(fb_info))
-
return -ENOSYS;
-
/* check all firmware fbs and kick off if the base addr overlaps */
-
for (i = 0 ; i < FB_MAX; i++) {
-
if (!registered_fb[i])
-
continue;
-
if (registered_fb[i]->flags & FBINFO_MISC_FIRMWARE) {
-
if (fb_do_apertures_overlap(registered_fb[i], fb_info)) {
-
printk(KERN_ERR "fb: conflicting fb hw usage "
-
"%s vs %s - removing generic driver\n",
-
fb_info->fix.id,
-
registered_fb[i]->fix.id);
-
unregister_framebuffer(registered_fb[i]);
-
break;
-
}
-
}
-
}
-
num_registered_fb++;
-
for (i = 0 ; i < FB_MAX; i++)
-
if (!registered_fb[i])
-
break;
-
fb_info->node = i;
-
mutex_init(&fb_info->lock);
-
mutex_init(&fb_info->mm_lock);
-
fb_info->dev = device_create(fb_class, fb_info->device,
-
MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
-
if (IS_ERR(fb_info->dev)) {
-
/* Not fatal */
-
printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));
-
fb_info->dev = NULL;
-
} else
-
fb_init_device(fb_info);
-
if (fb_info->pixmap.addr == NULL) {
-
fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);
-
if (fb_info->pixmap.addr) {
-
fb_info->pixmap.size = FBPIXMAPSIZE;
-
fb_info->pixmap.buf_align = 1;
-
fb_info->pixmap.scan_align = 1;
-
fb_info->pixmap.access_align = 32;
-
fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;
-
}
-
}
-
fb_info->pixmap.offset = 0;
-
if (!fb_info->pixmap.blit_x)
-
fb_info->pixmap.blit_x = ~(u32)0;
-
if (!fb_info->pixmap.blit_y)
-
fb_info->pixmap.blit_y = ~(u32)0;
-
if (!fb_info->modelist.prev || !fb_info->modelist.next)
-
INIT_LIST_HEAD(&fb_info->modelist);
-
fb_var_to_videomode(&mode, &fb_info->var);
-
fb_add_videomode(&mode, &fb_info->modelist);
-
registered_fb[i] = fb_info; //这里放入info到registered_fb
-
event.info = fb_info;
-
if (!lock_fb_info(fb_info))
-
return -ENODEV;
-
fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
-
unlock_fb_info(fb_info);
-
return 0;
-
}
可以知道是通过register_framebuffer这个函数放进去的,register_framebuffer又是谁调用的?搜索代码可以知道很多文件都有调用,看S3c2410fb.c可以看到这个在s3c24xxfb_probe里面被调用的,而s3c24xxfb_probe就是s3c24xx这种CPU的LCD驱动程序,这里挂到虚拟总线上了:
-
static struct platform_driver s3c2410fb_driver = {
-
.probe = s3c2410fb_probe,
-
.remove = s3c2410fb_remove,
-
.suspend = s3c2410fb_suspend,
-
.resume = s3c2410fb_resume,
-
.driver = {
-
.name = "s3c2410-lcd",
-
.owner = THIS_MODULE,
-
},
-
};
-
int __init s3c2410fb_init(void)
-
{
-
int ret = platform_driver_register(&s3c2410fb_driver);
-
if (ret == 0)
-
ret = platform_driver_register(&s3c2412fb_driver);
-
return ret;
-
}
-
static void __exit s3c2410fb_cleanup(void)
-
{
-
platform_driver_unregister(&s3c2410fb_driver);
-
platform_driver_unregister(&s3c2412fb_driver);
-
}
-
module_init(s3c2410fb_init);
-
module_exit(s3c2410fb_cleanup);
-
MODULE_AUTHOR("Arnaud Patard <[email protected]>, "
-
"Ben Dooks <[email protected]>");
-
MODULE_DESCRIPTION("Framebuffer driver for the s3c2410");
-
MODULE_LICENSE("GPL");
-
MODULE_ALIAS("platform:s3c2410-lcd");
-
MODULE_ALIAS("platform:s3c2412-lcd");
所以可以知道最开始看的那个fbmem.c就是LCD驱动的driver端(叫做FrameBuffer驱动),而这边跟平台有关的S3c2410fb.c等就是LCD驱动的divice端,这个跟之前分析的输入子系统很类似,也是分离的思想,把成熟的软件框架与硬件平台分开,软件框架(driver端)已经帮我们实现了,我们只需要编写divece端,最后把device注册到driver端就可以了。下面看看如何编写device端:
从S3c2410fb.c可以知道我们的LCD驱动就是按要求设置好这个info,然后注册到LCD驱动核心层。这里为了分析思路的清晰,先不考虑虚拟总线,我们自己写一个驱动照着填好这个info,然后设置好跟LCD有关的寄存器就差不多了,然后注册到LCD驱动核心。
1 先把框架写好:
-
#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 <asm/arch/regs-lcd.h>
-
#include <asm/arch/regs-gpio.h>
-
#include <asm/arch/fb.h>
-
static struct fb_info *s3c_lcd;
-
static int lcd_init(void)
-
{
-
/* 1. 分配一个fb_info */
-
s3c_lcd = framebuffer_alloc(0, NULL);
-
/* 2. 设置 */
-
/* 2.1 设置固定的参数 fix */
-
/* 2.2 设置可变的参数 var */
-
/* 2.3 设置操作函数 fbops*/
-
/* 2.4 其他的设置 */
-
/* 3. 硬件相关的操作 */
-
/* 3.1 配置GPIO用于LCD */
-
/* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
-
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
-
/* 4. 注册 */
-
register_framebuffer(s3c_lcd);
-
return 0;
-
}
-
static void lcd_exit(void)
-
{
-
}
-
module_init(lcd_init);
-
module_exit(lcd_exit);
-
MODULE_LICENSE("GPL");
看下这个info哪些有必要设置:
-
struct fb_info {
-
int node;
-
int flags;
-
struct mutex lock; /* Lock for open/release/ioctl funcs */
-
struct mutex mm_lock; /* Lock for fb_mmap and smem_* fields */
-
struct fb_var_screeninfo var; /* Current var */
-
struct fb_fix_screeninfo fix; /* Current fix */
-
struct fb_monspecs monspecs; /* Current Monitor specs */
-
struct work_struct queue; /* Framebuffer event queue */
-
struct fb_pixmap pixmap; /* Image hardware mapper */
-
struct fb_pixmap sprite; /* Cursor hardware mapper */
-
struct fb_cmap cmap; /* Current cmap */
-
struct list_head modelist; /* mode list */
-
struct fb_videomode *mode; /* current mode */
-
#ifdef CONFIG_FB_BACKLIGHT
-
/* assigned backlight device */
-
/* set before framebuffer registration,
-
remove after unregister */
-
struct backlight_device *bl_dev;
-
/* Backlight level curve */
-
struct mutex bl_curve_mutex;
-
u8 bl_curve[FB_BACKLIGHT_LEVELS];
-
#endif
-
#ifdef CONFIG_FB_DEFERRED_IO
-
struct delayed_work deferred_work;
-
struct fb_deferred_io *fbdefio;
-
#endif
-
struct fb_ops *fbops;
-
struct device *device; /* This is the parent */
-
struct device *dev; /* This is this fb device */
-
int class_flag; /* private sysfs flags */
-
#ifdef CONFIG_FB_TILEBLITTING
-
struct fb_tile_ops *tileops; /* Tile Blitting */
-
#endif
-
char __iomem *screen_base; /* Virtual address */
-
unsigned long screen_size; /* Amount of ioremapped VRAM or 0 */
-
void *pseudo_palette; /* Fake palette of 16 colors */
-
#define FBINFO_STATE_RUNNING 0
-
#define FBINFO_STATE_SUSPENDED 1
-
u32 state; /* Hardware state i.e suspend */
-
void *fbcon_par; /* fbcon use-only private area */
-
/* From here on everything is device dependent */
-
void *par;
-
/* we need the PCI or similiar aperture base/size not
-
smem_start/size as smem_start may just be an object
-
allocated inside the aperture so may not actually overlap */
-
resource_size_t aperture_base;
-
resource_size_t aperture_size;
-
};
2 然后来看下info的设置:
-
#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 <asm/arch/regs-lcd.h>
-
#include <asm/arch/regs-gpio.h>
-
#include <asm/arch/fb.h>
-
//对显存的一些操作函数:
-
static struct fb_ops s3c_lcdfb_ops = {
-
.owner = THIS_MODULE,
-
// .fb_setcolreg = atmel_lcdfb_setcolreg,
-
.fb_fillrect = cfb_fillrect, //这三个照着写,以后再分析
-
.fb_copyarea = cfb_copyarea,
-
.fb_imageblit = cfb_imageblit,
-
};
-
static struct fb_info *s3c_lcd;
-
static int lcd_init(void)
-
{
-
/* 1. 分配一个fb_info */
-
s3c_lcd = framebuffer_alloc(0, NULL);
-
/* 2. 设置 */
-
/* 2.1 设置固定的参数 */
-
strcpy(s3c_lcd->fix.id, "mylcd"); //名称
-
s3c_lcd->fix.smem_len = 240*320*16/8; //显存大小,16bpp所以16位表示一个像素点,240x320的屏幕有240x320个点,再x16就是总位数,再/8就是总字节数
-
s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS;
-
s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; /* TFT 真彩色*/
-
s3c_lcd->fix.line_length = 240*2; //一行的长度,一行240个点,每个点两个字节(16bit),所以*2
-
/* 2.2 设置可变的参数 */
-
s3c_lcd->var.xres = 240; //行
-
s3c_lcd->var.yres = 320; //列
-
s3c_lcd->var.xres_virtual = 240; //这里设置虚拟屏,我们设置虚拟屏为一样大小
-
s3c_lcd->var.yres_virtual = 320;
-
s3c_lcd->var.bits_per_pixel = 16; //每个像素16位
-
/* RGB:565 */
-
s3c_lcd->var.red.offset = 11; //16位表示一个像素点的格式是R:G:B分别占5:6:5位
-
s3c_lcd->var.red.length = 5;
-
s3c_lcd->var.green.offset = 5;
-
s3c_lcd->var.green.length = 6;
-
s3c_lcd->var.blue.offset = 0;
-
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; //对显存的操作函数,透明处理等操作
-
/* 2.4 其他的设置 */
-
//s3c_lcd->pseudo_palette =; //
-
//s3c_lcd->screen_base = ; /* 显存的虚拟地址 */
-
s3c_lcd->screen_size = 240*324*16/8; //和显存大小一样设置
-
/* 3. 硬件相关的操作 */
-
/* 3.1 配置GPIO用于LCD */
-
/* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
-
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
-
//s3c_lcd->fix.smem_start = xxx; /* 显存的物理地址 */
-
/* 4. 注册 */
-
register_framebuffer(s3c_lcd);
-
return 0;
-
}
-
static void lcd_exit(void)
-
{
-
}
-
module_init(lcd_init);
-
module_exit(lcd_exit);
-
MODULE_LICENSE("GPL");
3 info一般设置这些东西,再看些硬件方面的设置:
-
#include <linux/module.h>
-
#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/fb.h>
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#include <linux/init.h>
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#include <linux/dma-mapping.h>
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#include <linux/interrupt.h>
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#include <linux/workqueue.h>
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#include <linux/wait.h>
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#include <linux/platform_device.h>
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#include <linux/clk.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <asm/div64.h>
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#include <asm/mach/map.h>
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#include <asm/arch/regs-lcd.h>
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#include <asm/arch/regs-gpio.h>
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#include <asm/arch/fb.h>
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static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
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unsigned int green, unsigned int blue,
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unsigned int transp, struct fb_info *info);
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struct lcd_regs {
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unsigned long lcdcon1;
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unsigned long lcdcon2;
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unsigned long lcdcon3;
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unsigned long lcdcon4;
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unsigned long lcdcon5;
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unsigned long lcdsaddr1;
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unsigned long lcdsaddr2;
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unsigned long lcdsaddr3;
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unsigned long redlut;
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unsigned long greenlut;
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unsigned long bluelut;
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unsigned long reserved[9];
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unsigned long dithmode;
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unsigned long tpal;
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unsigned long lcdintpnd;
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unsigned long lcdsrcpnd;
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unsigned long lcdintmsk;
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unsigned long lpcsel;
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};
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static struct fb_ops s3c_lcdfb_ops = {
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.owner = THIS_MODULE,
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.fb_setcolreg = s3c_lcdfb_setcolreg,
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.fb_fillrect = cfb_fillrect,
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.fb_copyarea = cfb_copyarea,
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.fb_imageblit = cfb_imageblit,
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};
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static struct fb_info *s3c_lcd;
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static volatile unsigned long *gpbcon;
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static volatile unsigned long *gpbdat;
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static volatile unsigned long *gpccon;
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static volatile unsigned long *gpdcon;
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static volatile unsigned long *gpgcon;
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static volatile struct lcd_regs* lcd_regs;
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static u32 pseudo_palette[16];
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/* from pxafb.c */
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static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
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{
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chan &= 0xffff;
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chan >>= 16 - bf->length;
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return chan << bf->offset;
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}
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static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
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unsigned int green, unsigned int blue,
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unsigned int transp, struct fb_info *info)
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{
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unsigned int val;
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if (regno > 16)
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return 1;
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/* 用red,green,blue三原色构造出val */
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val = chan_to_field(red, &info->var.red);
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val |= chan_to_field(green, &info->var.green);
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val |= chan_to_field(blue, &info->var.blue);
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//((u32 *)(info->pseudo_palette))[regno] = val;
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pseudo_palette[regno] = val;
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return 0;
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}
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static int lcd_init(void)
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{
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/* 1. 分配一个fb_info */
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s3c_lcd = framebuffer_alloc(0, NULL);
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/* 2. 设置 */
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/* 2.1 设置固定的参数 */
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strcpy(s3c_lcd->fix.id, "mylcd");
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s3c_lcd->fix.smem_len = 240*320*16/8;
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s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS;
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s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; /* TFT */
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s3c_lcd->fix.line_length = 240*2;
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/* 2.2 设置可变的参数 */
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s3c_lcd->var.xres = 240;
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s3c_lcd->var.yres = 320;
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s3c_lcd->var.xres_virtual = 240;
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s3c_lcd->var.yres_virtual = 320;
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s3c_lcd->var.bits_per_pixel = 16;
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/* RGB:565 */
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s3c_lcd->var.red.offset = 11;
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s3c_lcd->var.red.length = 5;
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s3c_lcd->var.green.offset = 5;
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s3c_lcd->var.green.length = 6;
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s3c_lcd->var.blue.offset = 0;
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s3c_lcd->var.blue.length = 5;
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s3c_lcd->var.activate = FB_ACTIVATE_NOW;
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/* 2.3 设置操作函数 */
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s3c_lcd->fbops = &s3c_lcdfb_ops;
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/* 2.4 其他的设置 */
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s3c_lcd->pseudo_palette = pseudo_palette;
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//s3c_lcd->screen_base = ; /* 显存的虚拟地址 */
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s3c_lcd->screen_size = 240*324*16/8;
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/* 3. 硬件相关的操作 */
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/* 3.1 配置GPIO用于LCD */
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gpbcon = ioremap(0x56000010, 8);
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gpbdat = gpbcon+1;
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gpccon = ioremap(0x56000020, 4);
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gpdcon = ioremap(0x56000030, 4);
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gpgcon = ioremap(0x56000060, 4);
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*gpccon = 0xaaaaaaaa; /* GPIO管脚用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND */
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*gpdcon = 0xaaaaaaaa; /* GPIO管脚用于VD[23:8] */
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*gpbcon &= ~(3); /* GPB0设置为输出引脚 */
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*gpbcon |= 1;
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*gpbdat &= ~1; /* 输出低电平 */
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*gpgcon |= (3<<8); /* GPG4用作LCD_PWREN */
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/* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
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lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));
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/* bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手册P14
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* 10MHz(100ns) = 100MHz / [(CLKVAL+1) x 2]
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* CLKVAL = 4
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* bit[6:5]: 0b11, TFT LCD
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* bit[4:1]: 0b1100, 16 bpp for TFT
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* bit[0] : 0 = Disable the video output and the LCD control signal.
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*/
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lcd_regs->lcdcon1 = (4<<8) | (3<<5) | (0x0c<<1);
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/* 垂直方向的时间参数
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* bit[31:24]: VBPD, VSYNC之后再过多长时间才能发出第1行数据
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* LCD手册 T0-T2-T1=4
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* VBPD=3
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* bit[23:14]: 多少行, 320, 所以LINEVAL=320-1=319
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* bit[13:6] : VFPD, 发出最后一行数据之后,再过多长时间才发出VSYNC
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* LCD手册T2-T5=322-320=2, 所以VFPD=2-1=1
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* bit[5:0] : VSPW, VSYNC信号的脉冲宽度, LCD手册T1=1, 所以VSPW=1-1=0
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*/
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lcd_regs->lcdcon2 = (3<<24) | (319<<14) | (1<<6) | (0<<0);
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/* 水平方向的时间参数
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* bit[25:19]: HBPD, VSYNC之后再过多长时间才能发出第1行数据
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* LCD手册 T6-T7-T8=17
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* HBPD=16
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* bit[18:8]: 多少列, 240, 所以HOZVAL=240-1=239
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* bit[7:0] : HFPD, 发出最后一行里最后一个象素数据之后,再过多长时间才发出HSYNC
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* LCD手册T8-T11=251-240=11, 所以HFPD=11-1=10
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*/
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lcd_regs->lcdcon3 = (16<<19) | (239<<8) | (10<<0);
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/* 水平方向的同步信号
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* bit[7:0] : HSPW, HSYNC信号的脉冲宽度, LCD手册T7=5, 所以HSPW=5-1=4
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*/
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lcd_regs->lcdcon4 = 4;
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/* 信号的极性
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* bit[11]: 1=565 format
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* bit[10]: 0 = The video data is fetched at VCLK falling edge
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* bit[9] : 1 = HSYNC信号要反转,即低电平有效
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* bit[8] : 1 = VSYNC信号要反转,即低电平有效
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* bit[6] : 0 = VDEN不用反转
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* bit[3] : 0 = PWREN输出0
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* bit[1] : 0 = BSWP
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* bit[0] : 1 = HWSWP 2440手册P413
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*/
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lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);
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/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
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s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);
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lcd_regs->lcdsaddr1 = (s3c_lcd->fix.smem_start >> 1) & ~(3<<30);
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lcd_regs->lcdsaddr2 = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;
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lcd_regs->lcdsaddr3 = (240*16/16); /* 一行的长度(单位: 2字节) */
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//s3c_lcd->fix.smem_start = xxx; /* 显存的物理地址 */
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/* 启动LCD */
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lcd_regs->lcdcon1 |= (1<<0); /* 使能LCD控制器 */
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lcd_regs->lcdcon5 |= (1<<3); /* 使能LCD本身 */
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*gpbdat |= 1; /* 输出高电平, 使能背光 */
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/* 4. 注册 */
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register_framebuffer(s3c_lcd);
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return 0;
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}
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static void lcd_exit(void)
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{
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unregister_framebuffer(s3c_lcd);
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lcd_regs->lcdcon1 &= ~(1<<0); /* 关闭LCD本身 */
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*gpbdat &= ~1; /* 关闭背光 */
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dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);
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iounmap(lcd_regs);
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iounmap(gpbcon);
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iounmap(gpccon);
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iounmap(gpdcon);
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iounmap(gpgcon);
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framebuffer_release(s3c_lcd);
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}
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module_init(lcd_init);
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module_exit(lcd_exit);
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MODULE_LICENSE("GPL");