DA9034驱动程序阅读笔记(4)

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文章出处：http://www.limodev.cn/blog
作者联系方式：李先静 <xianjimli at hotmail dot com>

DA9034是一个集成了电源管理、音频设备、触摸屏控制器和能用A/D|D/A转换的多功能芯片。最近读了一下相关驱动程序，这里记些笔记，不成体系，作为备忘而已。有兴趣的朋友可以一起讨论。

DA9034的耳机插拔检测和线控开关检测的原理比较简单，因为不同状态电压不一样。插入耳机时，DA9034会上报中断给CPU，驱动程序在中断处理程序中查询相应的状态即可。
headset-detect

HEADSET detection carried out by comparing the voltage at the REM_IN node to a reference voltage that is 90% of
MICBIAS. A high level is detected as no external microphone present, while a low level is detected as a microphone present.

HOOK-SWITCH detection is carried out by comparing the voltage at the REM_IN node to a reference voltage that is 10% of
MICBIAS. A high level is detected as non-pressed button, while a low level is detected as a pressed button.

耳机检测是一个platform device，在littleton.c中定义：

static struct gpio_switch_platform_data headset = {
.name = "h2w",
.data = PMIC_EVENT_HSDETECT,
};
 
struct platform_device pxa_device_micco_switch1 = {
.name       = "switch-micco",
.id     = 0,
};
 
static struct gpio_switch_platform_data hook = {
.name = "hook",
.data = PMIC_EVENT_HOOKSWITCH,
};
 
struct platform_device pxa_device_micco_switch2 = {
.name       = "switch-micco",
.id     = 1,
};

驱动程序有三个实现版本：

其一是:drivers/char/micco_hsdetect.c
它通过kobject_uevent上报状态给用户空间。

其二是：drivers/input/keyboard/micco_keys.c
它通过input_report_switch上报事件给用户空间。

其三是：drivers/switch/switch_micco.c
注册了一个switch_dev，这个好像是android平台专用的。

不管哪种实现方式，都是在收到PMIC_EVENT_HSDETECT/PMIC_EVENT_HOOKSWITCH事件，读取DA9034的寄存器MICCO_STATUS_B，来查询相应状态。

static void micco_switch_interrupt(unsigned long event)
{
struct micco_switch_data *switch_data;
u8 val;
int state;
 
if (event&amp;PMIC_EVENT_HSDETECT) {
micco_read(MICCO_STATUS_B, &amp;val);
state = (val &amp; MICCO_STATUS_B_HEADSET)? 1 : 0;
 
printk("PMIC_EVENT_HSDETECT %s/n", state?"PLUG IN":"REMOVED");
switch_data = gswitch_data[HEADSET_SWITCH];
if (switch_data)
switch_set_state(&amp;(switch_data-&gt;sdev), state);
}
 
if (event&amp;PMIC_EVENT_HOOKSWITCH) {
micco_read(MICCO_STATUS_B, &amp;val);
state = (val &amp; MICCO_STATUS_B_HOOKSWITCH)? 1 : 0;
 
printk("PMIC_EVENT_HOOKSWITCH %s/n", state?"PRESSED":"RELEASED");
switch_data = gswitch_data[HOOK_SWITCH];
if (switch_data)
switch_set_state(&amp;(switch_data-&gt;sdev), state);
}
}