一、request_threaded_irq()
1、文件
kernel/irq/manage.c
2、定义
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id){
...
#
/*
Sanity-check: shared interrupts must pass in a real dev-ID,
otherwise we'll have trouble later trying to figure out
which interrupt is which (messes up the interrupt freeing
logic etc).
Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
it cannot be set along with IRQF_NO_SUSPEND.
/
if (((irqflags & IRQF_SHARED) && !dev_id) ||
(!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
return -EINVAL;
#
desc = irq_to_desc(irq);
...
action->handler = handler;
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
...
#
retval = __setup_irq(irq, desc, action);
...}
说明：
1）、irq：要申请的中断号，可通过platform_get_irq()获取，见“Linux内核中断之获取中断号”。
2）、handler：中断处理函数，发生中断时，先处理中断处理函数，然后返回IRQ_WAKE_THREAD唤醒中断处理线程。中断处理函数尽可能简单。
中断处理函数定义：typedef irqreturn_t (*irq_handler_t)(int, void *);
中断返回值如下：
/**
enum irqreturn
@IRQ_NONE interrupt was not from this device or was not handled
@IRQ_HANDLED interrupt was handled by this device
@IRQ_WAKE_THREAD handler requests to wake the handler thread
/
enum irqreturn {
IRQ_NONE = (0 << 0),
IRQ_HANDLED = (1 << 0),
IRQ_WAKE_THREAD = (1 << 1),
3）、thread_fn：中断处理线程，该参数可为NULL。类似于中断处理函数的下半部分。
4）、irqflags：中断类型标志。
定义文件：include/linux/interrupt.h，内容如下：
#define IRQF_TRIGGER_NONE 0x00000000
#define IRQF_TRIGGER_RISING 0x00000001 ## 上升沿触发中断
#define IRQF_TRIGGER_FALLING 0x00000002 ## 下降沿沿触发中断
#define IRQF_TRIGGER_HIGH 0x00000004 ## 高电平触发中断
#define IRQF_TRIGGER_LOW 0x00000008 ## 低电平触发中断...
#define IRQF_SHARED 0x00000080 ## 多设备共享中断...
5）、devname：中断名称，可使用cat /proc/interrupts命令查看。
6）、dev_id：设备ID，该值唯一。
在使用共享中断时（即设置IRQF_SHARED），必须传入dev_id，在中断处理和释放函数中都会使用该参数。
注：
1、request_threaded_irq()函数可替代request_irq加tasklet或workqueue的方式。
2、对应的中断释放函数为：void free_irq(unsigned int, void *)，需要和中断申请函数成对出现。
二、request_irq()
1、文件
include/linux/interrupt.h
2、定义
static inline int __must_checkrequest_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev){
return request_threaded_irq(irq, handler, NULL, flags, name, dev);}
说明：
1）、__must_check：指调用函数一定要处理函数的返回值，否则编译器会给出警告。
2）、request_irq()函数本质上是中断处理线程thread_fn为空的request_threaded_irq()函数。
注 ：
对应的中断释放函数为：void free_irq(unsigned int, void *)，需要和中断申请函数成对出现。
三、devm_request_threaded_irq()
1、文件
kernel/irq/devres.c
2、定义
int devm_request_threaded_irq(struct device *dev, unsigned int irq,
irq_handler_t handler, irq_handler_t thread_fn,
unsigned long irqflags, const char *devname,
void *dev_id){
...
## 1.申请设备资源
dr = devres_alloc(devm_irq_release, sizeof(struct irq_devres),
GFP_KERNEL);
...
## 2.调用request_threaded_irq()函数
rc = request_threaded_irq(irq, handler, thread_fn, irqflags, devname,
dev_id);
...
## 3.添加到设备资源列表中
devres_add(dev, dr);
...}
说明 ：
devm_request_threaded_irq()本质上还是使用request_threaded_irq()函数实现中断申请。
两者区别：
1）多了一个dev参数；
2）在设备驱动卸载时，中断会自动释放；
3）如果想单独释放中断，可使用void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id)函数。
四、devm_request_irq()
1、文件
include/linux/interrupt.h
2、定义
static inline int __must_checkdevm_request_irq(struct device *dev, unsigned int irq, irq_handler_t handler,
unsigned long irqflags, const char *devname, void *dev_id){
return devm_request_threaded_irq(dev, irq, handler, NULL, irqflags,
devname, dev_id);}
devm_request_irq()函数本质上是中断处理线程thread_fn为空的devm_request_threaded_irq()函数。
五、代码举例
1、获取中断号
static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
void *data){
...
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
...
ret = dw_hdmi_bind(dev, master, data, encoder, iores, irq, plat_data);
...}
2、申请中断
int dw_hdmi_bind(struct device *dev, struct device *master,
void *data, struct drm_encoder *encoder,
struct resource *iores, int irq,
const struct dw_hdmi_plat_data *plat_data){
...
## 申请中断，使用的是IRQF_SHARED，dev_id必须传入参数
ret = devm_request_threaded_irq(dev, irq, dw_hdmi_hardirq,
dw_hdmi_irq, IRQF_SHARED,
dev_name(dev), hdmi);
...}
3、中断处理函数
static irqreturn_t dw_hdmi_hardirq(int irq, void *dev_id){
...
irqreturn_t ret = IRQ_NONE; ## 中断返回值
...
intr_stat = hdmi_readb(hdmi, HDMI_IH_PHY_STAT0);
if (intr_stat) {
hdmi_writeb(hdmi, ~0, HDMI_IH_MUTE_PHY_STAT0);
return IRQ_WAKE_THREAD; ## 中断返回值，唤醒中断处理线程
}
...
return ret;}
4、中断处理线程
static irqreturn_t dw_hdmi_irq(int irq, void *dev_id){
struct dw_hdmi *hdmi = dev_id;
...
hdcp_stat = hdmi_readb(hdmi, HDMI_A_APIINTSTAT);
if (hdcp_stat) {
if (hdmi->hdcp && hdmi->hdcp->hdcp_isr)
hdmi->hdcp->hdcp_isr(hdmi->hdcp, hdcp_stat);
hdmi_writeb(hdmi, hdcp_stat, HDMI_A_APIINTCLR);
hdmi_writeb(hdmi, 0x00, HDMI_A_APIINTMSK);
}
return IRQ_HANDLED;
5、查看中断
原作者：DMCF
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