---> http://www.unjeep.com/q/625260162.htm
http://blog.csdn.net/aree/article/details/28683741
http://blog.csdn.net/jxnu_xiaobing/article/details/16805623
一、kpd_pdrv_probe函数的分析:
/*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
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:
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
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
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
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:
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。