背光驱动内核层及驱动层分析

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一些重要的结构体：

struct mt65xx_led_data {

structled_classdev cdev;

structcust_mt65xx_led cust;

structwork_struct work;

intlevel;

intdelay_on;

intdelay_off;

};

struct led_classdev {

constchar *name;

int brightness;

int max_brightness;

int flags;

/*Lower 16 bits reflect status */

#define LED_SUSPENDED (1 << 0)

/*Upper 16 bits reflect control information */

#define LED_CORE_SUSPENDRESUME (1 << 16)

#define LED_BLINK_ONESHOT (1 << 17)

#define LED_BLINK_ONESHOT_STOP (1 << 18)

#define LED_BLINK_INVERT (1 << 19)

/*Set LED brightness level */

/*Must not sleep, use a workqueue if needed */

void (*brightness_set)(struct led_classdev*led_cdev,

enumled_brightness brightness);

/*Get LED brightness level */

enumled_brightness (*brightness_get)(struct led_classdev *led_cdev);

* Activate hardware accelerated blink, delaysare in milliseconds

* and if both are zero then a sensible defaultshould be chosen.

* The call should adjust the timings in thatcase and if it can't

* match the values specified exactly.

* Deactivate blinking again when thebrightness is set to a fixed

* value via the brightness_set() callback.

int (*blink_set)(struct led_classdev*led_cdev,

unsigned long *delay_on,

unsigned long *delay_off);

structdevice *dev;

structlist_head node; /* LED Device list */

constchar *default_trigger; /* Trigger to use */

unsignedlong blink_delay_on,blink_delay_off;

structtimer_list blink_timer;

int blink_brightness;

structwork_struct set_brightness_work;

int delayed_set_value;

#ifdef CONFIG_LEDS_TRIGGERS

/*Protects the trigger data below */

structrw_semaphore trigger_lock;

structled_trigger *trigger;

structlist_head trig_list;

void *trigger_data;

/*true if activated - deactivate routine uses it to do cleanup */

bool activated;

#endif

};

struct cust_mt65xx_led {

char *name;

enummt65xx_led_mode mode;

long data;

struct PWM_config config_data;

};

struct work_struct {

atomic_long_tdata;

structlist_head entry;

work_func_tfunc;

#ifdef CONFIG_LOCKDEP

structlockdep_map lockdep_map;

#endif

};

Linux的背光驱动层

Probe：驱动函数

mt65xx_leds_probe

//设置全局数组g_leds_data

g_leds_data[i]->cust.mode= cust_led_list[i].mode;

…….

g_leds_data[i]->cdev.brightness_set= mt65xx_led_set;

mt_mt65xx_led_set //(leds.c)

schedule_work(&led_data->work);

mt_mt65xx_led_set_cust

INIT_WORK(&g_leds_data[i]->work,mt_mt65xx_led_work);

ret =led_classdev_register(&pdev->dev, &g_leds_data[i]->cdev); //led-class.c里定义

if (strcmp(g_leds_data[i]->cdev.name,"lcd-backlight") == 0) {

rc= device_create_file(g_leds_data[i]->cdev.dev, &dev_attr_duty);

if(rc) {

LEDS_DRV_DEBUG("[LED]device_create_fileduty fail!\n");

}

……………..

ret =led_classdev_register(&pdev->dev, &g_leds_data[i]->cdev); //led-class.c里定义

led_cdev->dev= device_create(leds_class, parent, 0, led_cdev,"%s",led_cdev->name);

//实现了创建的节点的方法

staticint __init leds_init(void)

{

leds_class= class_create(THIS_MODULE, "leds");

if(IS_ERR(leds_class))

returnPTR_ERR(leds_class);

leds_class->suspend= led_suspend;

leds_class->resume= led_resume;

leds_class->dev_attrs= led_class_attrs;

return0;

}

static struct device_attributeled_class_attrs[] = {

__ATTR(brightness,0644, led_brightness_show, led_brightness_store),

__ATTR(max_brightness,0444, led_max_brightness_show, NULL),

#ifdef CONFIG_LEDS_TRIGGERS

__ATTR(trigger,0644, led_trigger_show, led_trigger_store),

#endif

__ATTR_NULL,

};

static ssize_t led_brightness_store(structdevice *dev,

structdevice_attribute *attr, const char *buf, size_t size)

{

structled_classdev *led_cdev = dev_get_drvdata(dev);

unsignedlong state;

ssize_tret = -EINVAL;

ret= kstrtoul(buf, 10, &state);

if(ret)

returnret;

if(state == LED_OFF)

led_trigger_remove(led_cdev);

__led_set_brightness(led_cdev,state); //这里实现了写节点时立马就设置背光的原理

returnsize;

}

设置背光函数原理：
case MT65XX_LED_MODE_CUST_BLS_PWM:

if(strcmp(cust->name, "lcd-backlight") == 0) {

bl_brightness_hal= level;

}

//mdelay(5000);

LEDS_DEBUG("BLSbrightness mapping value:%ld\n",((long)((level*CONFIG_LIGHTNESS_MAPPING_VALUE)/255)));

return((cust_set_brightness) (cust->data)) ((long)(level*CONFIG_LIGHTNESS_MAPPING_VALUE/255) );

//其实调用的是disp_bls_set_backlight函数，cust_leds.c里定义

分析disp_bls_set_backlight

disp_bls_set_backlight

disp_pwm_set_backlight

disp_pwm_set_backlight_cmdq

level_1024= disp_pwm_level_remap(id, level_1024);

//这里可以设置上层和底层之间的映射

DISP_REG_MASK(cmdq,reg_base + DISP_PWM_CON_1_OFF, level_1024 << 16, 0x1fff << 16);

//设置背光，PWM寄存器配置

alps\kernel-3.10\drivers\misc\mediatek\dispsys\mt6735\ddp_pwm.c

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