開發闆:tiny4412SDK + S702 + 4GB Flash
要移植的核心版本:Linux-4.4.0 (支援device tree)
u-boot版本:友善之臂自帶的 U-Boot 2010.12
busybox版本:busybox 1.25
目标:
學習裝置樹中GPIO資源的使用,實作按鍵中斷簡單驅動程式。
原理圖:
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiI0NXYFhGd192UvwVe0lmdhJ3ZvwFM38CXlZHbvN3cpR2Lc1TPB10QGtWUCpEMJ9CXsxWam9CXwADNvwVZ6l2c052bm9CXUJDT1wkNhVzLcRnbvZ2LclHNXFWa5cFZ2w2RiZXUYpVd1kmYr50MZV3YyI2cKJDT29GRjBjUIF2LcRHelR3LcJzLctmch1mclRXY39zN3MTOxYTM3ETNxEDM3EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
tiny4412 底闆上有4顆按鍵,分别為連接配接在 GPX3_2、GPX3_3、GPX3_4、GPX3_5 ,引腳狀态常高。
裝置樹:
interrupt_demo: interrupt_demo {
compatible = "tiny4412,interrupt_demo";
tiny4412,int_gpio1 = <&gpx3 2 GPIO_ACTIVE_HIGH>;
tiny4412,int_gpio2 = <&gpx3 3 GPIO_ACTIVE_HIGH>;
tiny4412,int_gpio3 = <&gpx3 4 GPIO_ACTIVE_HIGH>;
tiny4412,int_gpio4 = <&gpx3 5 GPIO_ACTIVE_HIGH>;
};
<&gpx3 2 GPIO_ACTIVE_HIGHT> 代表什麼含義呢?
Eg: <&gpx2 6 0>
<[phandle of the gpio controller node]
[pin number within the gpio controller]
[flags]>
Values for gpio specifier:
- Pin number: is a value between 0 to 7.
- Flags: 0 - Active High 1 - Active Low
- &gpx3 引用 gpx3 這個節點,代表這個 GPIO 是屬于控制器 gpx3
- 2 則表示gpx3 這組管腳中的哪一個,gpx3_2
- GPIO_ACTIVE_HIGHT 則表示引腳狀态為常高的
驅動程式:
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/interrupt.h>
typedef struct
{
int gpio;
int irq;
char name[];
}int_demo_data_t;
static irqreturn_t int_demo_isr(int irq, void *dev_id)
{
int_demo_data_t *data = dev_id;
printk("%s enter, %s: gpio:%d, irq: %d\n", __func__, data->name, data->gpio, data->irq);
return IRQ_HANDLED;
}
static int int_demo_probe(struct platform_device *pdev) {
struct device *dev = &pdev->dev;
int irq_gpio = -;
int irq = -;
int ret = ;
int i = ;
int_demo_data_t *data = NULL;
printk("%s enter.\n", __func__);
if (!dev->of_node) {
dev_err(dev, "no platform data.\n");
goto err1;
}
data = devm_kmalloc(dev, sizeof(*data)*, GFP_KERNEL);
if (!data) {
dev_err(dev, "no memory.\n");
goto err0;
}
#if 1
for (i = ; i >= ; i--) {
sprintf(data[i].name, "tiny4412,int_gpio%d", i+);//名字是我們自己填充的,并不是擷取到的
#else
for (i = ; i < ; i++) {
#endif
irq_gpio = of_get_named_gpio(dev->of_node, data[i].name, );//通過名字擷取gpio
if (irq_gpio < ) {
dev_err(dev, "Looking up %s property in node %s failed %d\n",
data[i].name, dev->of_node->full_name, irq_gpio);
goto err1;
}
data[i].gpio = irq_gpio;
irq = gpio_to_irq(irq_gpio); //将gpio轉換成對應的中斷号
if (irq < ) {
dev_err(dev,
"Unable to get irq number for GPIO %d, error %d\n",
irq_gpio, irq);
goto err1;
}
data[i].irq = irq;
printk("%s: gpio: %d ---> irq (%d)\n", __func__, irq_gpio, irq);
//注冊中斷
ret = devm_request_any_context_irq(dev, irq, int_demo_isr, IRQF_TRIGGER_FALLING, data[i].name, data+i);
if (ret < ) {
dev_err(dev, "Unable to claim irq %d; error %d\n",
irq, ret);
goto err1;
}
}
return ;
err1:
devm_kfree(dev, data);
err0:
return -EINVAL;
}
static int int_demo_remove(struct platform_device *pdev) {
printk("%s enter.\n", __func__);
return ;
}
static const struct of_device_id int_demo_dt_ids[] = {
{ .compatible = "tiny4412,interrupt_demo", },
{},
};
MODULE_DEVICE_TABLE(of, int_demo_dt_ids);
static struct platform_driver int_demo_driver = {
.driver = {
.name = "interrupt_demo",
.of_match_table = of_match_ptr(int_demo_dt_ids),
},
.probe = int_demo_probe,
.remove = int_demo_remove,
};
static int __init int_demo_init(void)
{
int ret;
ret = platform_driver_register(&int_demo_driver);
if (ret)
printk(KERN_ERR "int demo: probe failed: %d\n", ret);
return ret;
}
module_init(int_demo_init);
static void __exit int_demo_exit(void)
{
platform_driver_unregister(&int_demo_driver);
}
module_exit(int_demo_exit);
MODULE_LICENSE("GPL");