Android LCD(四)：LCD驱动调试篇
2013-11-11 11:02
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这篇我们以一个实例来说明,Samsung Exynos4412搭配TTL转LVDS芯片SN75LVDS83B、LVDS接口LCD为例说明。从硬件接口、驱动配置、背光PWM调节三部分说明。
下载：SN75LVDS83B规格书
一、LCD接口原理以及硬件电路
Samsung Exynos4412、SN75LVDS83B、LVDS接口LCD（24bit）为例说明，三者的关系如下：
如上图所示，我们在应用中我，主控（Exynos4412）输出RGB信号到TFT-LCD大体经过三部分：
（1）、标号1部分，主控（Exynos4412）输出TTL信号；
（2）、标号2部分，TTL（RGB）-LVDS转换芯片SN75LVDS83B,把ＴＴＬ信号转换成LVDS信号，传输到显示器的LVDS接收端；这部分有SN75LVDS83B编码芯片自动完成，所以我们不需要程序控制；
（3）、标号3部分，分两个小部分，LVDS转换成TTL，TFT-LCD显示部分；我们前面说过，TFT-LCD其实只识别TTL信号，所以要有一个转换的过程，先把LVDS信号转换、解码成TTL信号，在TFT-LCD上显示。
有上面的过程，其实我们关心调试的部分只有标号1部分到标号2部分，后面标号2到标号3的部分是自动完成的，不需要我们程序上控制，把标号2部分、标号3部分合并：
标号二部分可以理解为一个TTL（RGB）接口的LCD,如下图所示，标号一部分就是主控信号输出端，简化图如下所示:
其实最简单的做法就是找个TTL接口的TFT-LCD，这样直接接上就可以。下面我们看下硬件上的电路连接：这个和我们上篇用的相同。
有上面图可以看出：硬件连接
上面可分为几部分，电路连接部分分析：
（1）、TTL数据部分
这张图有木有烂掉呀，哈哈，就是这些数据了。还有有木有想起来摄像头的数据（ITU接口）也是这样的？？其实视频这种信号的原理是通用的，所以LCD通了，摄像头也就知道怎么回事了。
（2）、PWM背光调节
PWM其实也是芯片的一个功能模块，看到他的管脚就是一个复用脚XpwmTOUT1/LCD_PWM/GPD0_1。上一篇我们粗略的了解了PWM，就是用到这里。但是有一个疑问，PWM是调节背光电压的，背光电压一般都是12V以上的，我们PWM只有0-3V的样子，Exynos4412的IO只有1.8V。怎么调节电压？？？
其实这个PWM只是给LCD上PWM控制部分，真正的电压还是通过LCD控制板上的电路实现。
（3）、LED背光、LCD电压控制
a、背光：LED+
我们可以看到这个升压电路，通过SY7208把VBATT升压到18V，供给LED背光。SY7208最大升压26V。这个电压是提供给我们前面讲的背光的，也就是CCFL灯管或者LED背光组的电压。
b、LCD电压
这个电压也就是给你我们TFT阵列组用的，控制LCD液晶元素。
这部分电路分析完成，我们就有比较清晰的思路出，要一个LCD工作，要完成两部分内容：LCD上电控制，背光、LCD电压；信号输出。
二、LCD 驱动部分调试
LCD这部分，像上篇我们说的frambuffer这些部分一般平台都是可以用的，除非你是芯片厂的要写这部分。一般公司拿到的demo板子这部分都是通的，只是针对自己的lCD换一些参数。
下面我们针对三星平台我们调试LCD的时时候程序方面的改动：
1、屏参数的配置
/kernel/drivers/video/Samsung/s3cfb_wa101s.c
[cpp]
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static struct s3cfb_lcd wa101 = {
.width = 1280,//LCD 分辨率宽1280
.height = 800, //LCD 分辨率高 800
.bpp = 24,//CLD 数据位 24bit
.freq = 60,//LCD 像素时钟 60MHz
.timing = {//LCD porch无效值
.h_fp = 70,
.h_bp = 70,
.h_sw = 20,
.v_fp = 10,
.v_fpe = 0,
.v_bp = 10,
.v_bpe = 0,
.v_sw = 3,
},
.polarity = {//时钟、行场的极性；
.rise_vclk = 1,
.inv_hsync = 1,
.inv_vsync = 1,
.inv_vden = 0,
},
};
/* name should be fixed as 's3cfb_set_lcd_info' */
void s3cfb_set_lcd_info(struct s3cfb_global *ctrl)//初始化结构体
{
wa101.init_ldi = NULL;
ctrl->lcd = &wa101;
#endif
}
还能想起上一篇的如何阅读规格书中的那些参数不，把这些填入就可以。
2、数据管脚初始化
kernel/arch/arm/mach-exynos/setup-fb-s5p.c
[cpp]
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void s3cfb_cfg_gpio(struct platform_device *pdev)
{
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF0(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF1(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF2(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF3(0), 4, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
}
LCD
数据脚初始化，驱动能力设为最高S5P_GPIO_DRVSTR_LV4；管脚驱动能力，S5P_GPIO_DRVSTR_LV1-4四个等级选择。
3、时钟控制部分
kernel/arch/arm/mach-exynos/setup-fb-s5p.c
[cpp]
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int s3cfb_clk_on(struct platform_device *pdev, struct clk **s3cfb_clk)
{
struct clk *sclk = NULL;
struct clk *mout_mpll = NULL;
struct clk *lcd_clk = NULL;
u32 rate = 0;
int ret = 0;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
dev_err(&pdev->dev, "failed to get operation clk for fimd\n");
goto err_clk0;
}
ret = clk_enable(lcd_clk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of lcd clk for fimd\n");
goto err_clk0;
}
clk_put(lcd_clk);
sclk = clk_get(&pdev->dev, "sclk_fimd");
if (IS_ERR(sclk)) {
dev_err(&pdev->dev, "failed to get sclk for fimd\n");
goto err_clk1;
}
if (soc_is_exynos4210())
mout_mpll = clk_get(&pdev->dev, "mout_mpll");
else
mout_mpll = clk_get(&pdev->dev, "mout_mpll_user");
if (IS_ERR(mout_mpll)) {
dev_err(&pdev->dev, "failed to get mout_mpll for fimd\n");
goto err_clk2;
}
ret = clk_set_parent(sclk, mout_mpll);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_parent for fimd\n");
goto err_clk2;
}
if ((soc_is_exynos4412()) && (samsung_rev() >= EXYNOS4412_REV_2_0))
ret = clk_set_rate(sclk, 880000000);
else
ret = clk_set_rate(sclk, 800000000);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_rate of sclk for fimd\n");
goto err_clk2;
}
dev_dbg(&pdev->dev, "set fimd sclk rate to %d\n", rate);
clk_put(mout_mpll);
ret = clk_enable(sclk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of sclk for fimd\n");
goto err_clk2;
}
*s3cfb_clk = sclk;
return 0;
err_clk2:
clk_put(mout_mpll);
err_clk1:
clk_put(sclk);
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
int s3cfb_clk_off(struct platform_device *pdev, struct clk **clk)
{
struct clk *lcd_clk = NULL;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
printk(KERN_ERR "failed to get ip clk for fimd0\n");
goto err_clk0;
}
clk_disable(lcd_clk);
clk_put(lcd_clk);
clk_disable(*clk);
clk_put(*clk);
*clk = NULL;
return 0;
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
void s3cfb_get_clk_name(char *clk_name)
{
strcpy(clk_name, "sclk_fimd");
}
4、背光、LCD电压的控制
[cpp]
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int s3cfb_backlight_on(struct platform_device *pdev)
{
int err;
pwm_set();
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_HIGH, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 1);
gpio_free(EXYNOS4_GPL2(4));
mdelay(20);
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPC1(2),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPC1(2), 0);
gpio_free(EXYNOS4_GPC1(2));
mdelay(20);
err = gpio_request(EXYNOS4_GPD0(1), "GPD0_1");
if (err) {
printk(KERN_ERR "failed to request GPD0_1 for "
"lcd pwm control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPD0(1),S3C_GPIO_PULL_NONE);
s5p_gpio_set_drvstr(EXYNOS4_GPD0(1), S5P_GPIO_DRVSTR_LV4);
gpio_direction_output(EXYNOS4_GPD0(1), 1);
s3c_gpio_cfgpin(EXYNOS4_GPD0(1), EXYNOS4_GPD_0_1_TOUT_1);
gpio_free(EXYNOS4_GPD0(1));
mdelay(20);
return 0;
return 0;
}
int s3cfb_backlight_off(struct platform_device *pdev)
{
int err;
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_LOW, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 0);
gpio_free(EXYNOS4_GPL2(4));
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
gpio_free(EXYNOS4_GPC1(2));
return 0;
}
5、PWM的设置
arch/arm/mach-exynos/mach-smdk4x12.c
[cpp]
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Arch/arm/mach-exynos/mach-smdk4x12.c
/* LCD Backlight data */
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};
static void __init smdk4x12_machine_init(void)
{
………………
samsung_bl_set(&smdk4x12_bl_gpio_info, &smdk4x12_bl_data);//在初始化的时候把对应的结构体初始化
………………
}
samsung_bl_set看下这个函数的实现：
kernel/arch/arm/palt-samsung/dev-backlight.c
[cpp]
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void samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
struct platform_pwm_backlight_data *bl_data)
{
int ret = 0;
struct platform_device *samsung_bl_device;
struct platform_pwm_backlight_data *samsung_bl_data;
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);//（1）、分配内存空间；
if (!samsung_bl_device) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
return;
}
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);//（2）、
if (!samsung_bl_data) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
goto err_data;
}
/* Copy board specific data provided by user */
samsung_bl_data->pwm_id = bl_data->pwm_id;//(3）、把具体配置的数据给samsung_bl_data
samsung_bl_device->dev.parent =
&s3c_device_timer[samsung_bl_data->pwm_id].dev;
if (bl_data->max_brightness)//(4)、对bl_data的结构体检查，如果没有复制则用default的值
samsung_bl_data->max_brightness = bl_data->max_brightness;
if (bl_data->dft_brightness)
samsung_bl_data->dft_brightness = bl_data->dft_brightness;
if (bl_data->lth_brightness)
samsung_bl_data->lth_brightness = bl_data->lth_brightness;
if (bl_data->pwm_period_ns)
samsung_bl_data->pwm_period_ns = bl_data->pwm_period_ns;
if (bl_data->init)
samsung_bl_data->init = bl_data->init;
if (bl_data->notify)
samsung_bl_data->notify = bl_data->notify;
if (bl_data->exit)
samsung_bl_data->exit = bl_data->exit;
if (bl_data->check_fb)
samsung_bl_data->check_fb = bl_data->check_fb;
/* Keep the GPIO info for future use */
s3c_device_timer[samsung_bl_data->pwm_id].dev.platform_data = gpio_info;
/* Register the specific PWM timer dev for Backlight control */
ret = platform_device_register(//(5)、注册PWM设备驱动；
&s3c_device_timer[samsung_bl_data->pwm_id]);
if (ret) {
printk(KERN_ERR "failed to register pwm timer for backlight: %d\n", ret);
goto err_plat_reg1;
}
/* Register the Backlight dev */
ret = platform_device_register(samsung_bl_device);//(6)、注册背光设备驱动；
if (ret) {
printk(KERN_ERR "failed to register backlight device: %d\n", ret);
goto err_plat_reg2;
}
return;
err_plat_reg2://(7)、如果有异常的情况下退出；
platform_device_unregister(&s3c_device_timer[samsung_bl_data->pwm_id]);
err_plat_reg1:
kfree(samsung_bl_data);
err_data:
kfree(samsung_bl_device);
return;
}
(1)、分配内存空间
[cpp]
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samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);
其中：
static struct platform_pwm_backlight_data samsung_dfl_bl_data = {
.max_brightness = 255,
.dft_brightness = 140,
.pwm_period_ns = 78770,
.init = samsung_bl_init,
.exit = samsung_bl_exit,
};
static struct platform_device samsung_dfl_bl_device = {
.name = "pwm-backlight",
};
(2)、
(3)、把具体配置的数据给samsung_bl_data
[cpp]
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arch/arm/mach-exynos/mach-smdk4x12.c
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};
(4)、对bl_data的结构体检查，如果没有复制则用default的值
参考（1）中的那些值。
(5)、注册PWM设备驱动；
[cpp]
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ret = platform_device_register(
&s3c_device_timer[samsung_bl_data->pwm_id]);
其中s3c_device_timer[]这个结构体如下：
[cpp]
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struct platform_device s3c_device_timer[] = {
[0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
[2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
[3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
[4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
我们饿samsung_bl_data->pwm_id=1;所以选择[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
(6)、注册背光设备驱动；
[cpp]
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ret =platform_device_register(samsung_bl_device);
其中：samsung_bl_device
[cpp]
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samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);
(7)、如果有异常的情况下退出；
6、PWM_BL背光驱动分析：
Kernel/drivers/video/backlight/pwm_bl.c
（1）、驱动注册：
[cpp]
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static struct platform_driver pwm_backlight_driver = {
.driver = {
.name = "pwm-backlight",
.owner = THIS_MODULE,
},
.probe = pwm_backlight_probe,
.remove = pwm_backlight_remove,
.suspend = pwm_backlight_suspend,
.resume = pwm_backlight_resume,
};
static int __init pwm_backlight_init(void)
{
return platform_driver_register(&pwm_backlight_driver);
}
（2）、probe函数分析
[cpp]
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static int pwm_backlight_probe(struct platform_device *pdev)
{
struct backlight_properties props;
struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
struct backlight_device *bl;
struct pwm_bl_data *pb;
int ret;
if (!data) {
dev_err(&pdev->dev, "failed to find platform data\n");
return -EINVAL;
}
if (data->init) {
ret = data->init(&pdev->dev);
if (ret < 0)
return ret;
}
pb = kzalloc(sizeof(*pb), GFP_KERNEL);
if (!pb) {
dev_err(&pdev->dev, "no memory for state\n");
ret = -ENOMEM;
goto err_alloc;
}
global_pb=pb;
INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);//1）、任务队列初始化；
pb->period = data->pwm_period_ns;//2）、pb结构体初始化；
pb->notify = data->notify;
pb->check_fb = data->check_fb;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
pb->pwm = pwm_request(data->pwm_id, "backlight");
if (IS_ERR(pb->pwm)) {
dev_err(&pdev->dev, "unable to request PWM for backlight\n");
ret = PTR_ERR(pb->pwm);
goto err_pwm;
} else
dev_dbg(&pdev->dev, "got pwm for backlight\n");
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = data->max_brightness;
bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
&pwm_backlight_ops, &props);
if (IS_ERR(bl)) {
dev_err(&pdev->dev, "failed to register backlight\n");
ret = PTR_ERR(bl);
goto err_bl;
}
global_bl=bl;
bl->props.brightness = data->dft_brightness;
backlight_update_status(bl);//3）、更新背光状态；
platform_set_drvdata(pdev, bl);
return 0;
err_bl:
pwm_free(pb->pwm);
err_pwm:
kfree(pb);
err_alloc:
if (data->exit)
data->exit(&pdev->dev);
return ret;
}
1）、任务队列初始化；
把key_event_work加入key_event队列，
[cpp]
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INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);
队列调度函数：
[cpp]
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static void key_event_work(struct work_struct *work)
{
global_pb->period=90000;
global_bl->props.brightness=global_brightness;
backlight_update_status(global_bl);
return ;
}
backlight_update_status
[cpp]
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static inline void backlight_update_status(struct backlight_device *bd)
{
mutex_lock(&bd->update_lock);
if (bd->ops && bd->ops->update_status)
bd->ops->update_status(bd);
mutex_unlock(&bd->update_lock);
}
update_status在pwm_backlight_ops结构体重指定：
[cpp]
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static const struct backlight_ops pwm_backlight_ops = {
.update_status = pwm_backlight_update_status,
…………}
pwm_backlight_update_status我们后面分析，这个其实就是我们PWM设定实现的具体实施过程。
2）、pb结构体初始化；
[cpp]
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pb->period = data->pwm_period_ns; pb->notify = data->notify;
pb->check_fb = data->check_fb;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
pb->pwm = pwm_request(data->pwm_id, "backlight");
3）、更新背光状态
[cpp]
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backlight_update_status(bl);
（4）、PWM_SET
当UI设置PWM时，会调用到驱动中的pwm_set(void)这个函数。这个函数主要在开机时使用。
[cpp]
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int pwm_set(void)
{
int error;
struct backlight_device *bl = global_bl;
struct pwm_bl_data *pb = global_pb;
printk("%s__%d\n",__func__,pb->period);
pb->period=410000;
backlight_update_status(bl);
schedule_delayed_work(&key_event, 600); //调用队列，跟新亮度信息；
return 0;
}
（5）、pwm_backlight_update_status这个就是PWM变化的具体实现，当应用层调节时，会调用到这个函数，把改变的值填入寄存器。
[cpp]
view plaincopyprint?
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
int brightness = bl->props.brightness;
int max = bl->props.max_brightness;
//if(brightness==0)
// return 0;
//printk("#####%s#%d__%d\n",__func__,pb->period,brightness);
global_brightness=brightness;
if (bl->props.power != FB_BLANK_UNBLANK)
brightness = 0;
if (bl->props.fb_blank != FB_BLANK_UNBLANK)
brightness = 0;
if (pb->notify)
brightness = pb->notify(pb->dev, brightness);
if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
} else {
#if 1
brightness = pb->lth_brightness +
(brightness * (pb->period - pb->lth_brightness) / max);
#else
brightness = pb->lth_brightness +
(((pb->period - pb->lth_brightness) / max) * brightness );
#endif
pwm_config(pb->pwm, brightness, pb->period);//这里对PWM寄存器的具体操作；
pwm_enable(pb->pwm);
}
return 0;
}
三、LCD UBOOT下的控制（待整理…………）
LCD在UBOOT下的控制，这部分我们没做过，后面有机会做了再把这部分完善，或者找个机会把代码详细看看。
下载：SN75LVDS83B规格书
一、LCD接口原理以及硬件电路
Samsung Exynos4412、SN75LVDS83B、LVDS接口LCD（24bit）为例说明，三者的关系如下：
如上图所示，我们在应用中我，主控（Exynos4412）输出RGB信号到TFT-LCD大体经过三部分：
（1）、标号1部分，主控（Exynos4412）输出TTL信号；
（2）、标号2部分，TTL（RGB）-LVDS转换芯片SN75LVDS83B,把ＴＴＬ信号转换成LVDS信号，传输到显示器的LVDS接收端；这部分有SN75LVDS83B编码芯片自动完成，所以我们不需要程序控制；
（3）、标号3部分，分两个小部分，LVDS转换成TTL，TFT-LCD显示部分；我们前面说过，TFT-LCD其实只识别TTL信号，所以要有一个转换的过程，先把LVDS信号转换、解码成TTL信号，在TFT-LCD上显示。
有上面的过程，其实我们关心调试的部分只有标号1部分到标号2部分，后面标号2到标号3的部分是自动完成的，不需要我们程序上控制，把标号2部分、标号3部分合并：
标号二部分可以理解为一个TTL（RGB）接口的LCD,如下图所示，标号一部分就是主控信号输出端，简化图如下所示:
其实最简单的做法就是找个TTL接口的TFT-LCD，这样直接接上就可以。下面我们看下硬件上的电路连接：这个和我们上篇用的相同。
有上面图可以看出：硬件连接
| 网络标号 | 说明 | 管脚 |
| XvVD[0：23] XvVDEN XvVSYNC XvHSYNC XvVCLK | RGB数据、使能、行场同步、时钟信号 | 这是TTL信号输出 |
| LCD_PWM | 调节背光 | XpwmTOUT1/LCD_PWM/GPD0_1 |
| LCD_LED_EN | LCD电压（TFT电压）使能 | GPC1_2 |
| LED_BL_EN | LED背光使能 | GPL2_4 |
（1）、TTL数据部分
这张图有木有烂掉呀，哈哈，就是这些数据了。还有有木有想起来摄像头的数据（ITU接口）也是这样的？？其实视频这种信号的原理是通用的，所以LCD通了，摄像头也就知道怎么回事了。
（2）、PWM背光调节
PWM其实也是芯片的一个功能模块，看到他的管脚就是一个复用脚XpwmTOUT1/LCD_PWM/GPD0_1。上一篇我们粗略的了解了PWM，就是用到这里。但是有一个疑问，PWM是调节背光电压的，背光电压一般都是12V以上的，我们PWM只有0-3V的样子，Exynos4412的IO只有1.8V。怎么调节电压？？？
其实这个PWM只是给LCD上PWM控制部分，真正的电压还是通过LCD控制板上的电路实现。
（3）、LED背光、LCD电压控制
a、背光：LED+
我们可以看到这个升压电路，通过SY7208把VBATT升压到18V，供给LED背光。SY7208最大升压26V。这个电压是提供给我们前面讲的背光的，也就是CCFL灯管或者LED背光组的电压。
b、LCD电压
这个电压也就是给你我们TFT阵列组用的，控制LCD液晶元素。
这部分电路分析完成，我们就有比较清晰的思路出，要一个LCD工作，要完成两部分内容：LCD上电控制，背光、LCD电压；信号输出。
二、LCD 驱动部分调试
LCD这部分，像上篇我们说的frambuffer这些部分一般平台都是可以用的，除非你是芯片厂的要写这部分。一般公司拿到的demo板子这部分都是通的，只是针对自己的lCD换一些参数。
下面我们针对三星平台我们调试LCD的时时候程序方面的改动：
1、屏参数的配置
/kernel/drivers/video/Samsung/s3cfb_wa101s.c
[cpp]
view plaincopyprint?
static struct s3cfb_lcd wa101 = {
.width = 1280,//LCD 分辨率宽1280
.height = 800, //LCD 分辨率高 800
.bpp = 24,//CLD 数据位 24bit
.freq = 60,//LCD 像素时钟 60MHz
.timing = {//LCD porch无效值
.h_fp = 70,
.h_bp = 70,
.h_sw = 20,
.v_fp = 10,
.v_fpe = 0,
.v_bp = 10,
.v_bpe = 0,
.v_sw = 3,
},
.polarity = {//时钟、行场的极性；
.rise_vclk = 1,
.inv_hsync = 1,
.inv_vsync = 1,
.inv_vden = 0,
},
};
/* name should be fixed as 's3cfb_set_lcd_info' */
void s3cfb_set_lcd_info(struct s3cfb_global *ctrl)//初始化结构体
{
wa101.init_ldi = NULL;
ctrl->lcd = &wa101;
#endif
}
static struct s3cfb_lcd wa101 = {
.width = 1280,//LCD 分辨率宽1280
.height = 800, //LCD 分辨率高 800
.bpp = 24,//CLD 数据位 24bit
.freq = 60,//LCD 像素时钟 60MHz
.timing = {//LCD porch无效值
.h_fp = 70,
.h_bp = 70,
.h_sw = 20,
.v_fp = 10,
.v_fpe = 0,
.v_bp = 10,
.v_bpe = 0,
.v_sw = 3,
},
.polarity = {//时钟、行场的极性；
.rise_vclk = 1,
.inv_hsync = 1,
.inv_vsync = 1,
.inv_vden = 0,
},
};
/* name should be fixed as 's3cfb_set_lcd_info' */
void s3cfb_set_lcd_info(struct s3cfb_global *ctrl)//初始化结构体
{
wa101.init_ldi = NULL;
ctrl->lcd = &wa101;
#endif
}还能想起上一篇的如何阅读规格书中的那些参数不，把这些填入就可以。
2、数据管脚初始化
kernel/arch/arm/mach-exynos/setup-fb-s5p.c
[cpp]
view plaincopyprint?
void s3cfb_cfg_gpio(struct platform_device *pdev)
{
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF0(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF1(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF2(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF3(0), 4, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
}
void s3cfb_cfg_gpio(struct platform_device *pdev)
{
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF0(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF1(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF2(0), 8, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
s3cfb_gpio_setup_24bpp(EXYNOS4_GPF3(0), 4, S3C_GPIO_SFN(2), S5P_GPIO_DRVSTR_LV4);
}LCD
数据脚初始化，驱动能力设为最高S5P_GPIO_DRVSTR_LV4；管脚驱动能力，S5P_GPIO_DRVSTR_LV1-4四个等级选择。
3、时钟控制部分
kernel/arch/arm/mach-exynos/setup-fb-s5p.c
[cpp]
view plaincopyprint?
int s3cfb_clk_on(struct platform_device *pdev, struct clk **s3cfb_clk)
{
struct clk *sclk = NULL;
struct clk *mout_mpll = NULL;
struct clk *lcd_clk = NULL;
u32 rate = 0;
int ret = 0;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
dev_err(&pdev->dev, "failed to get operation clk for fimd\n");
goto err_clk0;
}
ret = clk_enable(lcd_clk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of lcd clk for fimd\n");
goto err_clk0;
}
clk_put(lcd_clk);
sclk = clk_get(&pdev->dev, "sclk_fimd");
if (IS_ERR(sclk)) {
dev_err(&pdev->dev, "failed to get sclk for fimd\n");
goto err_clk1;
}
if (soc_is_exynos4210())
mout_mpll = clk_get(&pdev->dev, "mout_mpll");
else
mout_mpll = clk_get(&pdev->dev, "mout_mpll_user");
if (IS_ERR(mout_mpll)) {
dev_err(&pdev->dev, "failed to get mout_mpll for fimd\n");
goto err_clk2;
}
ret = clk_set_parent(sclk, mout_mpll);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_parent for fimd\n");
goto err_clk2;
}
if ((soc_is_exynos4412()) && (samsung_rev() >= EXYNOS4412_REV_2_0))
ret = clk_set_rate(sclk, 880000000);
else
ret = clk_set_rate(sclk, 800000000);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_rate of sclk for fimd\n");
goto err_clk2;
}
dev_dbg(&pdev->dev, "set fimd sclk rate to %d\n", rate);
clk_put(mout_mpll);
ret = clk_enable(sclk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of sclk for fimd\n");
goto err_clk2;
}
*s3cfb_clk = sclk;
return 0;
err_clk2:
clk_put(mout_mpll);
err_clk1:
clk_put(sclk);
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
int s3cfb_clk_off(struct platform_device *pdev, struct clk **clk)
{
struct clk *lcd_clk = NULL;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
printk(KERN_ERR "failed to get ip clk for fimd0\n");
goto err_clk0;
}
clk_disable(lcd_clk);
clk_put(lcd_clk);
clk_disable(*clk);
clk_put(*clk);
*clk = NULL;
return 0;
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
void s3cfb_get_clk_name(char *clk_name)
{
strcpy(clk_name, "sclk_fimd");
}
int s3cfb_clk_on(struct platform_device *pdev, struct clk **s3cfb_clk)
{
struct clk *sclk = NULL;
struct clk *mout_mpll = NULL;
struct clk *lcd_clk = NULL;
u32 rate = 0;
int ret = 0;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
dev_err(&pdev->dev, "failed to get operation clk for fimd\n");
goto err_clk0;
}
ret = clk_enable(lcd_clk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of lcd clk for fimd\n");
goto err_clk0;
}
clk_put(lcd_clk);
sclk = clk_get(&pdev->dev, "sclk_fimd");
if (IS_ERR(sclk)) {
dev_err(&pdev->dev, "failed to get sclk for fimd\n");
goto err_clk1;
}
if (soc_is_exynos4210())
mout_mpll = clk_get(&pdev->dev, "mout_mpll");
else
mout_mpll = clk_get(&pdev->dev, "mout_mpll_user");
if (IS_ERR(mout_mpll)) {
dev_err(&pdev->dev, "failed to get mout_mpll for fimd\n");
goto err_clk2;
}
ret = clk_set_parent(sclk, mout_mpll);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_parent for fimd\n");
goto err_clk2;
}
if ((soc_is_exynos4412()) && (samsung_rev() >= EXYNOS4412_REV_2_0))
ret = clk_set_rate(sclk, 880000000);
else
ret = clk_set_rate(sclk, 800000000);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_set_rate of sclk for fimd\n");
goto err_clk2;
}
dev_dbg(&pdev->dev, "set fimd sclk rate to %d\n", rate);
clk_put(mout_mpll);
ret = clk_enable(sclk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to clk_enable of sclk for fimd\n");
goto err_clk2;
}
*s3cfb_clk = sclk;
return 0;
err_clk2:
clk_put(mout_mpll);
err_clk1:
clk_put(sclk);
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
int s3cfb_clk_off(struct platform_device *pdev, struct clk **clk)
{
struct clk *lcd_clk = NULL;
lcd_clk = clk_get(&pdev->dev, "lcd");
if (IS_ERR(lcd_clk)) {
printk(KERN_ERR "failed to get ip clk for fimd0\n");
goto err_clk0;
}
clk_disable(lcd_clk);
clk_put(lcd_clk);
clk_disable(*clk);
clk_put(*clk);
*clk = NULL;
return 0;
err_clk0:
clk_put(lcd_clk);
return -EINVAL;
}
void s3cfb_get_clk_name(char *clk_name)
{
strcpy(clk_name, "sclk_fimd");
}4、背光、LCD电压的控制
| LCD_LED_EN | LCD电压（TFT电压）使能 | GPC1_2 |
| LED_BL_EN | LED背光使能 | GPL2_4 |
view plaincopyprint?
int s3cfb_backlight_on(struct platform_device *pdev)
{
int err;
pwm_set();
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_HIGH, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 1);
gpio_free(EXYNOS4_GPL2(4));
mdelay(20);
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPC1(2),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPC1(2), 0);
gpio_free(EXYNOS4_GPC1(2));
mdelay(20);
err = gpio_request(EXYNOS4_GPD0(1), "GPD0_1");
if (err) {
printk(KERN_ERR "failed to request GPD0_1 for "
"lcd pwm control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPD0(1),S3C_GPIO_PULL_NONE);
s5p_gpio_set_drvstr(EXYNOS4_GPD0(1), S5P_GPIO_DRVSTR_LV4);
gpio_direction_output(EXYNOS4_GPD0(1), 1);
s3c_gpio_cfgpin(EXYNOS4_GPD0(1), EXYNOS4_GPD_0_1_TOUT_1);
gpio_free(EXYNOS4_GPD0(1));
mdelay(20);
return 0;
return 0;
}
int s3cfb_backlight_off(struct platform_device *pdev)
{
int err;
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_LOW, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 0);
gpio_free(EXYNOS4_GPL2(4));
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
gpio_free(EXYNOS4_GPC1(2));
return 0;
}
int s3cfb_backlight_on(struct platform_device *pdev)
{
int err;
pwm_set();
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_HIGH, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 1);
gpio_free(EXYNOS4_GPL2(4));
mdelay(20);
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPC1(2),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPC1(2), 0);
gpio_free(EXYNOS4_GPC1(2));
mdelay(20);
err = gpio_request(EXYNOS4_GPD0(1), "GPD0_1");
if (err) {
printk(KERN_ERR "failed to request GPD0_1 for "
"lcd pwm control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPD0(1),S3C_GPIO_PULL_NONE);
s5p_gpio_set_drvstr(EXYNOS4_GPD0(1), S5P_GPIO_DRVSTR_LV4);
gpio_direction_output(EXYNOS4_GPD0(1), 1);
s3c_gpio_cfgpin(EXYNOS4_GPD0(1), EXYNOS4_GPD_0_1_TOUT_1);
gpio_free(EXYNOS4_GPD0(1));
mdelay(20);
return 0;
return 0;
}
int s3cfb_backlight_off(struct platform_device *pdev)
{
int err;
err = gpio_request_one(EXYNOS4_GPL2(4), GPIOF_OUT_INIT_LOW, "GPL2_4");
if (err) {
printk(KERN_ERR "failed to request GPL2 for "
"lcd backlight control\n");
return err;
}
s3c_gpio_setpull(EXYNOS4_GPL2(4),S3C_GPIO_PULL_NONE);
gpio_direction_output(EXYNOS4_GPL2(4), 0);
gpio_free(EXYNOS4_GPL2(4));
err = gpio_request_one(EXYNOS4_GPC1(2), GPIOF_OUT_INIT_HIGH, "GPC1_2");
if (err) {
printk(KERN_ERR "failed to request GPC1 for "
"lcd backlight control\n");
return err;
}
gpio_free(EXYNOS4_GPC1(2));
return 0;
}5、PWM的设置
arch/arm/mach-exynos/mach-smdk4x12.c
[cpp]
view plaincopyprint?
Arch/arm/mach-exynos/mach-smdk4x12.c
/* LCD Backlight data */
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};
static void __init smdk4x12_machine_init(void)
{
………………
samsung_bl_set(&smdk4x12_bl_gpio_info, &smdk4x12_bl_data);//在初始化的时候把对应的结构体初始化
………………
}
Arch/arm/mach-exynos/mach-smdk4x12.c
/* LCD Backlight data */
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};
static void __init smdk4x12_machine_init(void)
{
………………
samsung_bl_set(&smdk4x12_bl_gpio_info, &smdk4x12_bl_data);//在初始化的时候把对应的结构体初始化
………………
}samsung_bl_set看下这个函数的实现：
kernel/arch/arm/palt-samsung/dev-backlight.c
[cpp]
view plaincopyprint?
void samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
struct platform_pwm_backlight_data *bl_data)
{
int ret = 0;
struct platform_device *samsung_bl_device;
struct platform_pwm_backlight_data *samsung_bl_data;
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);//（1）、分配内存空间；
if (!samsung_bl_device) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
return;
}
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);//（2）、
if (!samsung_bl_data) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
goto err_data;
}
/* Copy board specific data provided by user */
samsung_bl_data->pwm_id = bl_data->pwm_id;//(3）、把具体配置的数据给samsung_bl_data
samsung_bl_device->dev.parent =
&s3c_device_timer[samsung_bl_data->pwm_id].dev;
if (bl_data->max_brightness)//(4)、对bl_data的结构体检查，如果没有复制则用default的值
samsung_bl_data->max_brightness = bl_data->max_brightness;
if (bl_data->dft_brightness)
samsung_bl_data->dft_brightness = bl_data->dft_brightness;
if (bl_data->lth_brightness)
samsung_bl_data->lth_brightness = bl_data->lth_brightness;
if (bl_data->pwm_period_ns)
samsung_bl_data->pwm_period_ns = bl_data->pwm_period_ns;
if (bl_data->init)
samsung_bl_data->init = bl_data->init;
if (bl_data->notify)
samsung_bl_data->notify = bl_data->notify;
if (bl_data->exit)
samsung_bl_data->exit = bl_data->exit;
if (bl_data->check_fb)
samsung_bl_data->check_fb = bl_data->check_fb;
/* Keep the GPIO info for future use */
s3c_device_timer[samsung_bl_data->pwm_id].dev.platform_data = gpio_info;
/* Register the specific PWM timer dev for Backlight control */
ret = platform_device_register(//(5)、注册PWM设备驱动；
&s3c_device_timer[samsung_bl_data->pwm_id]);
if (ret) {
printk(KERN_ERR "failed to register pwm timer for backlight: %d\n", ret);
goto err_plat_reg1;
}
/* Register the Backlight dev */
ret = platform_device_register(samsung_bl_device);//(6)、注册背光设备驱动；
if (ret) {
printk(KERN_ERR "failed to register backlight device: %d\n", ret);
goto err_plat_reg2;
}
return;
err_plat_reg2://(7)、如果有异常的情况下退出；
platform_device_unregister(&s3c_device_timer[samsung_bl_data->pwm_id]);
err_plat_reg1:
kfree(samsung_bl_data);
err_data:
kfree(samsung_bl_device);
return;
}
void samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
struct platform_pwm_backlight_data *bl_data)
{
int ret = 0;
struct platform_device *samsung_bl_device;
struct platform_pwm_backlight_data *samsung_bl_data;
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);//（1）、分配内存空间；
if (!samsung_bl_device) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
return;
}
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);//（2）、
if (!samsung_bl_data) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
goto err_data;
}
/* Copy board specific data provided by user */
samsung_bl_data->pwm_id = bl_data->pwm_id;//(3）、把具体配置的数据给samsung_bl_data
samsung_bl_device->dev.parent =
&s3c_device_timer[samsung_bl_data->pwm_id].dev;
if (bl_data->max_brightness)//(4)、对bl_data的结构体检查，如果没有复制则用default的值
samsung_bl_data->max_brightness = bl_data->max_brightness;
if (bl_data->dft_brightness)
samsung_bl_data->dft_brightness = bl_data->dft_brightness;
if (bl_data->lth_brightness)
samsung_bl_data->lth_brightness = bl_data->lth_brightness;
if (bl_data->pwm_period_ns)
samsung_bl_data->pwm_period_ns = bl_data->pwm_period_ns;
if (bl_data->init)
samsung_bl_data->init = bl_data->init;
if (bl_data->notify)
samsung_bl_data->notify = bl_data->notify;
if (bl_data->exit)
samsung_bl_data->exit = bl_data->exit;
if (bl_data->check_fb)
samsung_bl_data->check_fb = bl_data->check_fb;
/* Keep the GPIO info for future use */
s3c_device_timer[samsung_bl_data->pwm_id].dev.platform_data = gpio_info;
/* Register the specific PWM timer dev for Backlight control */
ret = platform_device_register(//(5)、注册PWM设备驱动；
&s3c_device_timer[samsung_bl_data->pwm_id]);
if (ret) {
printk(KERN_ERR "failed to register pwm timer for backlight: %d\n", ret);
goto err_plat_reg1;
}
/* Register the Backlight dev */
ret = platform_device_register(samsung_bl_device);//(6)、注册背光设备驱动；
if (ret) {
printk(KERN_ERR "failed to register backlight device: %d\n", ret);
goto err_plat_reg2;
}
return;
err_plat_reg2://(7)、如果有异常的情况下退出；
platform_device_unregister(&s3c_device_timer[samsung_bl_data->pwm_id]);
err_plat_reg1:
kfree(samsung_bl_data);
err_data:
kfree(samsung_bl_device);
return;
}(1)、分配内存空间
[cpp]
view plaincopyprint?
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);
其中：
static struct platform_pwm_backlight_data samsung_dfl_bl_data = {
.max_brightness = 255,
.dft_brightness = 140,
.pwm_period_ns = 78770,
.init = samsung_bl_init,
.exit = samsung_bl_exit,
};
static struct platform_device samsung_dfl_bl_device = {
.name = "pwm-backlight",
};
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);
其中：
static struct platform_pwm_backlight_data samsung_dfl_bl_data = {
.max_brightness = 255,
.dft_brightness = 140,
.pwm_period_ns = 78770,
.init = samsung_bl_init,
.exit = samsung_bl_exit,
};
static struct platform_device samsung_dfl_bl_device = {
.name = "pwm-backlight",
};(2)、
(3)、把具体配置的数据给samsung_bl_data
[cpp]
view plaincopyprint?
arch/arm/mach-exynos/mach-smdk4x12.c
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};
arch/arm/mach-exynos/mach-smdk4x12.c
static struct samsung_bl_gpio_info smdk4x12_bl_gpio_info = {
.no = EXYNOS4_GPD0(1),//PWM管脚XpwmTOUT1/LCD_PWM/GPD0_1
.func = S3C_GPIO_SFN(2),
};
static struct platform_pwm_backlight_data smdk4x12_bl_data = {
.pwm_id = 1,//PWM ID PWM编号为1号；
.pwm_period_ns = 90000, //22k
};(4)、对bl_data的结构体检查，如果没有复制则用default的值
参考（1）中的那些值。
(5)、注册PWM设备驱动；
[cpp]
view plaincopyprint?
ret = platform_device_register(
&s3c_device_timer[samsung_bl_data->pwm_id]);
ret = platform_device_register( &s3c_device_timer[samsung_bl_data->pwm_id]);
其中s3c_device_timer[]这个结构体如下：
[cpp]
view plaincopyprint?
struct platform_device s3c_device_timer[] = {
[0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
[2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
[3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
[4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
struct platform_device s3c_device_timer[] = {
[0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
[2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
[3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
[4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },我们饿samsung_bl_data->pwm_id=1;所以选择[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
(6)、注册背光设备驱动；
[cpp]
view plaincopyprint?
ret =platform_device_register(samsung_bl_device);
ret =platform_device_register(samsung_bl_device);
其中：samsung_bl_device
[cpp]
view plaincopyprint?
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data, sizeof(struct platform_pwm_backlight_data), samsung_bl_device);
(7)、如果有异常的情况下退出；
6、PWM_BL背光驱动分析：
Kernel/drivers/video/backlight/pwm_bl.c
（1）、驱动注册：
[cpp]
view plaincopyprint?
static struct platform_driver pwm_backlight_driver = {
.driver = {
.name = "pwm-backlight",
.owner = THIS_MODULE,
},
.probe = pwm_backlight_probe,
.remove = pwm_backlight_remove,
.suspend = pwm_backlight_suspend,
.resume = pwm_backlight_resume,
};
static int __init pwm_backlight_init(void)
{
return platform_driver_register(&pwm_backlight_driver);
}
static struct platform_driver pwm_backlight_driver = {
.driver = {
.name = "pwm-backlight",
.owner = THIS_MODULE,
},
.probe = pwm_backlight_probe,
.remove = pwm_backlight_remove,
.suspend = pwm_backlight_suspend,
.resume = pwm_backlight_resume,
};
static int __init pwm_backlight_init(void)
{
return platform_driver_register(&pwm_backlight_driver);
}（2）、probe函数分析
[cpp]
view plaincopyprint?
static int pwm_backlight_probe(struct platform_device *pdev)
{
struct backlight_properties props;
struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
struct backlight_device *bl;
struct pwm_bl_data *pb;
int ret;
if (!data) {
dev_err(&pdev->dev, "failed to find platform data\n");
return -EINVAL;
}
if (data->init) {
ret = data->init(&pdev->dev);
if (ret < 0)
return ret;
}
pb = kzalloc(sizeof(*pb), GFP_KERNEL);
if (!pb) {
dev_err(&pdev->dev, "no memory for state\n");
ret = -ENOMEM;
goto err_alloc;
}
global_pb=pb;
INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);//1）、任务队列初始化；
pb->period = data->pwm_period_ns;//2）、pb结构体初始化；
pb->notify = data->notify;
pb->check_fb = data->check_fb;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
pb->pwm = pwm_request(data->pwm_id, "backlight");
if (IS_ERR(pb->pwm)) {
dev_err(&pdev->dev, "unable to request PWM for backlight\n");
ret = PTR_ERR(pb->pwm);
goto err_pwm;
} else
dev_dbg(&pdev->dev, "got pwm for backlight\n");
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = data->max_brightness;
bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
&pwm_backlight_ops, &props);
if (IS_ERR(bl)) {
dev_err(&pdev->dev, "failed to register backlight\n");
ret = PTR_ERR(bl);
goto err_bl;
}
global_bl=bl;
bl->props.brightness = data->dft_brightness;
backlight_update_status(bl);//3）、更新背光状态；
platform_set_drvdata(pdev, bl);
return 0;
err_bl:
pwm_free(pb->pwm);
err_pwm:
kfree(pb);
err_alloc:
if (data->exit)
data->exit(&pdev->dev);
return ret;
}
static int pwm_backlight_probe(struct platform_device *pdev)
{
struct backlight_properties props;
struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
struct backlight_device *bl;
struct pwm_bl_data *pb;
int ret;
if (!data) {
dev_err(&pdev->dev, "failed to find platform data\n");
return -EINVAL;
}
if (data->init) {
ret = data->init(&pdev->dev);
if (ret < 0)
return ret;
}
pb = kzalloc(sizeof(*pb), GFP_KERNEL);
if (!pb) {
dev_err(&pdev->dev, "no memory for state\n");
ret = -ENOMEM;
goto err_alloc;
}
global_pb=pb;
INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);//1）、任务队列初始化；
pb->period = data->pwm_period_ns;//2）、pb结构体初始化；
pb->notify = data->notify;
pb->check_fb = data->check_fb;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
pb->pwm = pwm_request(data->pwm_id, "backlight");
if (IS_ERR(pb->pwm)) {
dev_err(&pdev->dev, "unable to request PWM for backlight\n");
ret = PTR_ERR(pb->pwm);
goto err_pwm;
} else
dev_dbg(&pdev->dev, "got pwm for backlight\n");
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = data->max_brightness;
bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
&pwm_backlight_ops, &props);
if (IS_ERR(bl)) {
dev_err(&pdev->dev, "failed to register backlight\n");
ret = PTR_ERR(bl);
goto err_bl;
}
global_bl=bl;
bl->props.brightness = data->dft_brightness;
backlight_update_status(bl);//3）、更新背光状态；
platform_set_drvdata(pdev, bl);
return 0;
err_bl:
pwm_free(pb->pwm);
err_pwm:
kfree(pb);
err_alloc:
if (data->exit)
data->exit(&pdev->dev);
return ret;
}1）、任务队列初始化；
把key_event_work加入key_event队列，
[cpp]
view plaincopyprint?
INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);
INIT_DELAYED_WORK_DEFERRABLE(&key_event, key_event_work);
队列调度函数：
[cpp]
view plaincopyprint?
static void key_event_work(struct work_struct *work)
{
global_pb->period=90000;
global_bl->props.brightness=global_brightness;
backlight_update_status(global_bl);
return ;
}
static void key_event_work(struct work_struct *work)
{
global_pb->period=90000;
global_bl->props.brightness=global_brightness;
backlight_update_status(global_bl);
return ;
}backlight_update_status
[cpp]
view plaincopyprint?
static inline void backlight_update_status(struct backlight_device *bd)
{
mutex_lock(&bd->update_lock);
if (bd->ops && bd->ops->update_status)
bd->ops->update_status(bd);
mutex_unlock(&bd->update_lock);
}
static inline void backlight_update_status(struct backlight_device *bd)
{
mutex_lock(&bd->update_lock);
if (bd->ops && bd->ops->update_status)
bd->ops->update_status(bd);
mutex_unlock(&bd->update_lock);
}update_status在pwm_backlight_ops结构体重指定：
[cpp]
view plaincopyprint?
static const struct backlight_ops pwm_backlight_ops = {
.update_status = pwm_backlight_update_status,
…………}
static const struct backlight_ops pwm_backlight_ops = {
.update_status = pwm_backlight_update_status,
…………}pwm_backlight_update_status我们后面分析，这个其实就是我们PWM设定实现的具体实施过程。
2）、pb结构体初始化；
[cpp]
view plaincopyprint?
pb->period = data->pwm_period_ns; pb->notify = data->notify;
pb->check_fb = data->check_fb;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
pb->pwm = pwm_request(data->pwm_id, "backlight");
pb->period = data->pwm_period_ns; pb->notify = data->notify; pb->check_fb = data->check_fb; pb->lth_brightness = data->lth_brightness * (data->pwm_period_ns / data->max_brightness); pb->dev = &pdev->dev; pb->pwm = pwm_request(data->pwm_id, "backlight");
3）、更新背光状态
[cpp]
view plaincopyprint?
backlight_update_status(bl);
backlight_update_status(bl);
（4）、PWM_SET
当UI设置PWM时，会调用到驱动中的pwm_set(void)这个函数。这个函数主要在开机时使用。
[cpp]
view plaincopyprint?
int pwm_set(void)
{
int error;
struct backlight_device *bl = global_bl;
struct pwm_bl_data *pb = global_pb;
printk("%s__%d\n",__func__,pb->period);
pb->period=410000;
backlight_update_status(bl);
schedule_delayed_work(&key_event, 600); //调用队列，跟新亮度信息；
return 0;
}
int pwm_set(void)
{
int error;
struct backlight_device *bl = global_bl;
struct pwm_bl_data *pb = global_pb;
printk("%s__%d\n",__func__,pb->period);
pb->period=410000;
backlight_update_status(bl);
schedule_delayed_work(&key_event, 600); //调用队列，跟新亮度信息；
return 0;
}（5）、pwm_backlight_update_status这个就是PWM变化的具体实现，当应用层调节时，会调用到这个函数，把改变的值填入寄存器。
[cpp]
view plaincopyprint?
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
int brightness = bl->props.brightness;
int max = bl->props.max_brightness;
//if(brightness==0)
// return 0;
//printk("#####%s#%d__%d\n",__func__,pb->period,brightness);
global_brightness=brightness;
if (bl->props.power != FB_BLANK_UNBLANK)
brightness = 0;
if (bl->props.fb_blank != FB_BLANK_UNBLANK)
brightness = 0;
if (pb->notify)
brightness = pb->notify(pb->dev, brightness);
if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
} else {
#if 1
brightness = pb->lth_brightness +
(brightness * (pb->period - pb->lth_brightness) / max);
#else
brightness = pb->lth_brightness +
(((pb->period - pb->lth_brightness) / max) * brightness );
#endif
pwm_config(pb->pwm, brightness, pb->period);//这里对PWM寄存器的具体操作；
pwm_enable(pb->pwm);
}
return 0;
}
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
int brightness = bl->props.brightness;
int max = bl->props.max_brightness;
//if(brightness==0)
// return 0;
//printk("#####%s#%d__%d\n",__func__,pb->period,brightness);
global_brightness=brightness;
if (bl->props.power != FB_BLANK_UNBLANK)
brightness = 0;
if (bl->props.fb_blank != FB_BLANK_UNBLANK)
brightness = 0;
if (pb->notify)
brightness = pb->notify(pb->dev, brightness);
if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
} else {
#if 1
brightness = pb->lth_brightness +
(brightness * (pb->period - pb->lth_brightness) / max);
#else
brightness = pb->lth_brightness +
(((pb->period - pb->lth_brightness) / max) * brightness );
#endif
pwm_config(pb->pwm, brightness, pb->period);//这里对PWM寄存器的具体操作；
pwm_enable(pb->pwm);
}
return 0;
}三、LCD UBOOT下的控制（待整理…………）
LCD在UBOOT下的控制，这部分我们没做过，后面有机会做了再把这部分完善，或者找个机会把代码详细看看。
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