MTK keypad driver

转自：http://blog.csdn.net/jxnu_xiaobing/article/details/16805623

一、kpd_pdrv_probe函数的分析：

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/*1. 输入设备实例 kpd_input_dev */

全局变量：static struct input_dev *kpd_input_dev;

static int kpd_pdrv_probe(struct platform_device *pdev)

{

int i, r;

u16 new_state[KPD_NUM_MEMS];

/* initialize and register input device (/dev/input/eventX) */

/*2. 初始化输入设备并分配内存空间*/

kpd_input_dev = input_allocate_device();

if (!kpd_input_dev)

return -ENOMEM;

/*下面开始填充kpd_input_dev 设备驱动结构体*/

kpd_input_dev->name = KPD_NAME;

kpd_input_dev->id.bustype = BUS_HOST;

kpd_input_dev->id.vendor = 0x2454;

kpd_input_dev->id.product = 0x6575;

kpd_input_dev->id.version = 0x0010;

kpd_input_dev->open = kpd_open;

/*3. 设置某位为1，以第二个参数为起始地址，EV_KEY表示要设置的位

作用：告诉input子系统支持那些事件， EV_KEY 这里表示告诉input子系统支持

按键事件

*/

__set_bit(EV_KEY, kpd_input_dev->evbit);

#if (KPD_PWRKEY_USE_EINT||KPD_PWRKEY_USE_PMIC)

/*4. 设置某位为1，以第二个参数为起始地址，EV_KEY表示要设置的位

作用：告诉input子系统支持那些按键， KPD_PWRKEY_MAP 这里表示告诉input子系统支持

电源按键

*/

__set_bit(KPD_PWRKEY_MAP, kpd_input_dev->keybit);

kpd_keymap[8] = 0;

#endif

for (i = 17; i < KPD_NUM_KEYS; i += 9) /* only [8] works for Power key */

kpd_keymap[i] = 0;

for (i = 0; i < KPD_NUM_KEYS; i++) {

if (kpd_keymap[i] != 0)

__set_bit(kpd_keymap[i], kpd_input_dev->keybit);

}

/*5. 上述几行代码表示设置电源按键 kpd_keymap 为0，其它按键 kpd_keymap 为1*/

__set_bit(250, kpd_input_dev->keybit);

__set_bit(251, kpd_input_dev->keybit);

#if KPD_AUTOTEST

for (i = 0; i < ARRAY_SIZE(kpd_auto_keymap); i++)

__set_bit(kpd_auto_keymap[i], kpd_input_dev->keybit);

#endif

#if KPD_HAS_SLIDE_QWERTY

__set_bit(EV_SW, kpd_input_dev->evbit);

__set_bit(SW_LID, kpd_input_dev->swbit);

__set_bit(SW_LID, kpd_input_dev->sw); /* 1: lid shut => closed */

#endif

#ifdef KPD_PMIC_RSTKEY_MAP

__set_bit(KPD_PMIC_RSTKEY_MAP, kpd_input_dev->keybit);

#endif

/*6. 指定kpd_input_dev这个平台设备sysfs中的父设备节点*/

kpd_input_dev->dev.parent = &pdev->dev;

/*7. 注册input输入子系统*/

r = input_register_device(kpd_input_dev);

if (r) {

printk(KPD_SAY "register input device failed (%d)\n", r);

input_free_device(kpd_input_dev);

return r;

}

/* register device (/dev/mt6575-kpd) */

/*7. 指定kpd_dev这个平台设备sysfs中的父设备节点*/

kpd_dev.parent = &pdev->dev;

/*8. 注册混杂设备*/

r = misc_register(&kpd_dev);

if (r) {

printk(KPD_SAY "register device failed (%d)\n", r);

input_unregister_device(kpd_input_dev);

return r;

}

/*8. 注册按键中断*/

/* register IRQ and EINT */

/*9. 设置消抖时间*/

kpd_set_debounce(KPD_KEY_DEBOUNCE);

/*10. 设置中断触发方式*/

mt65xx_irq_set_sens(MT6575_KP_IRQ_ID, MT65xx_EDGE_SENSITIVE);

/*11 . 设置中断优先级*/

mt65xx_irq_set_polarity(MT6575_KP_IRQ_ID, MT65xx_POLARITY_LOW);

/*12. 注册中断处理函数*/

r = request_irq(MT6575_KP_IRQ_ID, kpd_irq_handler, 0, KPD_NAME, NULL);

if (r) {

printk(KPD_SAY "register IRQ failed (%d)\n", r);

misc_deregister(&kpd_dev);

input_unregister_device(kpd_input_dev);

return r;

}

/*13. 以下为电源键中断函数的注册*/

#if KPD_PWRKEY_USE_EINT

mt65xx_eint_set_sens(KPD_PWRKEY_EINT, KPD_PWRKEY_SENSITIVE);

mt65xx_eint_set_hw_debounce(KPD_PWRKEY_EINT, KPD_PWRKEY_DEBOUNCE);

mt65xx_eint_registration(KPD_PWRKEY_EINT, true, KPD_PWRKEY_POLARITY,

kpd_pwrkey_eint_handler, false);

#endif

if(kpd_enable_lprst && get_boot_mode() == NORMAL_BOOT) {

kpd_print("Normal Boot\n");

#ifdef KPD_PMIC_LPRST_TD

kpd_print("Enable LPRST\n");

/*14. 以下为设置按键唤醒的时间*/

upmu_testmode_pwrkey_rst_en(0x01);

upmu_testmode_homekey_rst_en(0x01);

upmu_testmode_pwrkey_rst_td(KPD_PMIC_LPRST_TD);

#endif

} else {

kpd_print("Disable LPRST %d\n", kpd_enable_lprst);

}

/*15. 设置一个高精度定时器，并且定义了时间到期的回调函数 aee_timer_func*/

hrtimer_init(&aee_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

aee_timer.function = aee_timer_func;

/*以下为三个按键的初始化，也就是配置

注意，默认值gpio输出是0*/

#if 1 // ylliu add. dct default value does not work...

/* KCOL0: GPIO103: KCOL1: GPIO108, KCOL2: GPIO105, KCOL4: GPIO102 input + pull enable + pull up */

mt_set_gpio_mode(GPIO_KPD_KCOL0_PIN, GPIO_KPD_KCOL0_PIN_M_KP_COL);

mt_set_gpio_dir(GPIO_KPD_KCOL0_PIN, GPIO_DIR_IN);

mt_set_gpio_pull_enable(GPIO_KPD_KCOL0_PIN, GPIO_PULL_ENABLE);

mt_set_gpio_pull_select(GPIO_KPD_KCOL0_PIN, GPIO_PULL_UP);

mt_set_gpio_mode(GPIO_KPD_KCOL1_PIN, GPIO_KPD_KCOL1_PIN_M_KP_COL);

mt_set_gpio_dir(GPIO_KPD_KCOL1_PIN, GPIO_DIR_IN);

mt_set_gpio_pull_enable(GPIO_KPD_KCOL1_PIN, GPIO_PULL_ENABLE);

mt_set_gpio_pull_select(GPIO_KPD_KCOL1_PIN, GPIO_PULL_UP);

mt_set_gpio_mode(GPIO_KPD_KCOL2_PIN, GPIO_KPD_KCOL2_PIN_M_KP_COL);

mt_set_gpio_dir(GPIO_KPD_KCOL2_PIN, GPIO_DIR_IN);

mt_set_gpio_pull_enable(GPIO_KPD_KCOL2_PIN, GPIO_PULL_ENABLE);

mt_set_gpio_pull_select(GPIO_KPD_KCOL2_PIN, GPIO_PULL_UP);

mt_set_gpio_mode(GPIO_KPD_KCOL4_PIN, GPIO_KPD_KCOL4_PIN_M_KP_COL);

mt_set_gpio_dir(GPIO_KPD_KCOL4_PIN, GPIO_DIR_IN);

mt_set_gpio_pull_enable(GPIO_KPD_KCOL4_PIN, GPIO_PULL_ENABLE);

mt_set_gpio_pull_select(GPIO_KPD_KCOL4_PIN, GPIO_PULL_UP);

/* KROW0: GPIO98, KROW1: GPIO97: KROW2: GPIO95 output + pull disable + pull down */

mt_set_gpio_mode(GPIO_KPD_KROW0_PIN, GPIO_KPD_KROW0_PIN_M_KP_ROW);

mt_set_gpio_dir(GPIO_KPD_KROW0_PIN, GPIO_DIR_OUT);

mt_set_gpio_pull_enable(GPIO_KPD_KROW0_PIN, GPIO_PULL_DISABLE);

mt_set_gpio_pull_select(GPIO_KPD_KROW0_PIN, GPIO_PULL_DOWN);

// mt_set_gpio_mode(97, 1);

// mt_set_gpio_dir(97, 1);

// mt_set_gpio_pull_enable(97, 0);

// mt_set_gpio_pull_select(97, 0);

//

// mt_set_gpio_mode(95, 1);

// mt_set_gpio_dir(95, 1);

// mt_set_gpio_pull_enable(95, 0);

// mt_set_gpio_pull_select(95, 0);

#endif

// default disable backlight. reboot from recovery need this.

kpd_disable_backlight();

// store default state, resolve recovery bugs.

kpd_get_keymap_state(new_state);

memcpy(kpd_keymap_state, new_state, sizeof(new_state));

return 0;

}

二、当执行完面probe函数进行相关初始化后，这时候，当我们按键按下了，就会触发中断，进入中断服务子程序

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static irqreturn_t __tcmfunc kpd_irq_handler(int irq, void *dev_id)

{

/* use _nosync to avoid deadlock */

disable_irq_nosync(MT6575_KP_IRQ_ID);

tasklet_schedule(&kpd_keymap_tasklet);

return IRQ_HANDLED;

}

可以看到，中断服务程序里面执行了
tasklet_schedule(&kpd_keymap_tasklet);

跟踪代码可以发现，实际上是执行了这个函数kpd_keymap_handler，下面仔细分析

这个函数，详细注释如下：

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static void kpd_keymap_handler(unsigned long data)

{

int i, j;

bool pressed;

u16 new_state[KPD_NUM_MEMS], change, mask;

u16 hw_keycode, linux_keycode;

kpd_get_keymap_state(new_state); //首先读取键值，并且存放于new_state中

if (pmic_get_acc_state() == 1) {

for (i = 0; i < KPD_NUM_MEMS; i++) {

change = new_state[i] ^ kpd_keymap_state[i]; //进行异或操作，就是为了取出两者不同的值

if (!change)

continue;

for (j = 0; j < 16; j++) {

mask = 1U << j;

if (!(change & mask))

continue;

hw_keycode = (i << 4) + j; //i = 0, j = 1; //这里是得到hw_keycode的值

printk("hw_keycode = %d ,i = %d, j = %d \n",hw_keycode,i,j);

/* bit is 1: not pressed, 0: pressed */

pressed = !(new_state[i] & mask); //(new_state[i] & mask) = 0

if (kpd_show_hw_keycode) {

printk(KPD_SAY "(%s) HW keycode = %u\n",

pressed ? "pressed" : "released",

hw_keycode);

}

BUG_ON(hw_keycode >= KPD_NUM_KEYS);

linux_keycode = kpd_keymap[hw_keycode]; //这里的linux_keycode恒为零。

printk("linux_keycode = %d \n",linux_keycode);

if(unlikely(linux_keycode == 0)) {

if (hw_keycode == 1 && pressed) { // special key, SOS.

struct device *dev = &(kpd_input_dev->dev);

char *envp[] = { "SOS_pressed", NULL };

kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); //建立设备文件？

printk(KPD_SAY "SOS_pressed\n");

// used by recovery.

/*这个接口会向INPUT子系统上报按键（该按键被按下）*/

input_report_key(kpd_input_dev, 251, pressed); //如果上层检测到SOS_pressed就会做相应处理。

} else if (hw_keycode == 2 && pressed) { // special key, background.

struct device *dev = &(kpd_input_dev->dev);

char *envp[] = { "background_pressed", NULL };

kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

printk(KPD_SAY "background_pressed\n");

// used by recovery.

input_report_key(kpd_input_dev, 8, pressed);

} else if (hw_keycode == 4 && pressed) { // special key, mode.

struct device *dev = &(kpd_input_dev->dev);

char *envp[] = { "mode_pressed", NULL };

kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

printk(KPD_SAY "mode_pressed\n");

} else if (hw_keycode == 1 || hw_keycode == 2 || hw_keycode == 4) { // add this to turn off backlight.

printk(KPD_SAY "background or SOS or mode release!\n");

// used by recovery.

if (hw_keycode == 1)

input_report_key(kpd_input_dev, 251, pressed);

else if (hw_keycode == 2)

input_report_key(kpd_input_dev, 8, pressed);

} else {

kpd_print("Linux keycode = 0\n");

continue;

}

}

kpd_aee_handler(linux_keycode, pressed);

kpd_backlight_handler(pressed, linux_keycode);

input_report_key(kpd_input_dev, linux_keycode, pressed);

}

}

} else {

printk(KPD_SAY "acc off, ignore and key...\n");

}

memcpy(kpd_keymap_state, new_state, sizeof(new_state));

kpd_print("save new keymap state\n");

enable_irq(MT6575_KP_IRQ_ID);

}

三、kpd_aee_handler函数分析

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static void kpd_aee_handler(u32 keycode, u16 pressed) {

if(pressed) {

if(keycode == KEY_VOLUMEUP) {

__set_bit(0, &aee_pressed_keys);

} else if(keycode == KEY_VOLUMEDOWN) {

__set_bit(1, &aee_pressed_keys);

} else {

return;

}

kpd_update_aee_state();

} else {

if(keycode == KEY_VOLUMEUP) {

__clear_bit(0, &aee_pressed_keys);

} else if(keycode == KEY_VOLUMEDOWN) {

__clear_bit(1, &aee_pressed_keys);

} else {

return;

}

kpd_update_aee_state();

}

}

详细分析：

1.__set_bit(0, &aee_pressed_keys)，定义了一个：static u16 aee_pressed_keys;

所以__set_bit的意思是将aee_pressed_keys的bit0设置为1

2.相应的__clear_bit(0, &aee_pressed_keys);就是把aee_pressed_keys的bit0清零，

3.还有在内核的non-atomic.h文件中还有一些其它的位操作，记住__set_bit和set_bit的区别就

是前者是非原子操作，而后者是原子操作，所谓原子操作，意思是最小的执行单位，再其执行过

程中是不会被其他任务打断的。

四、背光处理函数

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void kpd_backlight_handler(bool pressed, u16 linux_keycode)

{

if (kpd_suspend && !test_bit(linux_keycode, kpd_wake_keybit)) {

kpd_print("Linux keycode %u is not WAKE key\n", linux_keycode);

return;

}

/* not in suspend or the key pressed is WAKE key */

if (pressed) {

atomic_inc(&kpd_key_pressed);

kpd_backlight_on = !!atomic_read(&kpd_key_pressed);

schedule_work(&kpd_backlight_work); //点亮背光灯

kpd_print("switch backlight on\n");

} else {

atomic_dec(&kpd_key_pressed);

mod_timer(&kpd_backlight_timer, //KPD_BACKLIGHT_TIME控制背光时间，单位为sec，如果注释掉这句，背光将不灭

jiffies + KPD_BACKLIGHT_TIME * HZ);

kpd_print("activate backlight timer\n");

}

}

详细分析

1.首先用到了一个位操作函数，注意这个函数是原子操作test_bit

2.全局变量static atomic_t kpd_key_pressed = ATOMIC_INIT(0);这是原子操作的初始化，kpd_key_pressed初始化为0

3.上述函数涉及到一些原子操作函数，解释如下：

atomic_inc(&kpd_key_pressed);
是对变量进行加1操作

atomic_dec(&kpd_key_pressed);
是对变量进行减1操作

!!atomic_read(&kpd_key_pressed);是读取变量的值，前面两个 !!强调该返回值不是1就是0：bool类型

4.mod_timer：该函数的作用是修改一个已经调度的定时器结构的到期时间。

五、背光控制函数

调度的是这个函数

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static void kpd_switch_backlight(struct work_struct *work)

{

if (kpd_backlight_on) {

kpd_enable_backlight();

kpd_print("backlight is on\n");

} else {

kpd_disable_backlight();

kpd_print("backlight is off\n");

}

}

这里就能够看到使能和失能背光的函数，继续跟踪：

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void kpd_enable_backlight(void)

{

/*mt6326_kpled_dim_duty_Full();

mt6326_kpled_Enable();*/

upmu_kpled_dim_duty(31);

upmu_kpled_en(1);

}

upmu_kpled_dim_duty这是控制背光电流大小从而可以控制亮度

upmu_kpled_en这是控制开关。

mod_timer函数的补充

http://www.360doc.com/content/12/0510/11/6973384_210041084.shtml

kpd驱动初步分析完毕。