本文转载自：http://blog.csdn.net/lizuobin2/article/details/54563587
开发板：tiny4412SDK + S702 + 4GB Flash
要移植的内核版本：Linux-4.4.0 （支持device tree）
u-boot版本：友善之臂自带的 U-Boot 2010.12
busybox版本：busybox 1.25
目标：
学习设备树中GPIO资源的使用，实现按键中断简单驱动程序。
原理图： 
tiny4412 底板上有4颗按键，分别为连接在 GPX3_2、GPX3_3、GPX3_4、GPX3_5 ，引脚状态常高。
设备树：
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>; };- 1
- 2
- 3
- 4
- 5
- 6
- 7
<&gpx3 2 GPIO_ACTIVE_HIGHT> 代表什么含义呢？
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 这个节点，代表这个 GPIO 是属于控制器 gpx3
- 2 则表示gpx3 这组管脚中的哪一个，gpx3_2
- GPIO_ACTIVE_HIGHT 则表示引脚状态为常高的
驱动程序：
#include
#include
#include
#include
#include #include #include typedef struct { int gpio; int irq; char name[20]; }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 = -1; int irq = -1; int ret = 0; int i = 0; 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)*4, GFP_KERNEL); if (!data) { dev_err(dev, "no memory.\n"); goto err0; } #if 1 for (i = 3; i >= 0; i--) { sprintf(data[i].name, "tiny4412,int_gpio%d", i+1);//名字是我们自己填充的，并不是获取到的 #else for (i = 0; i < 4; i++) { #endif irq_gpio = of_get_named_gpio(dev->of_node, data[i].name, 0);//通过名字获取gpio if (irq_gpio < 0) { 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转换成对应的中断号 if (irq < 0) { 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); //注册中断 ret = devm_request_any_context_irq(dev, irq, int_demo_isr, IRQF_TRIGGER_FALLING, data[i].name, data+i); if (ret < 0) { dev_err(dev, "Unable to claim irq %d; error %d\n", irq, ret); goto err1; } } return 0; err1: devm_kfree(dev, data); err0: return -EINVAL; } static int int_demo_remove(struct platform_device *pdev) { printk("%s enter.\n", __func__); return 0; } 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");