linux DTS gpio example

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http://developer.t-firefly.com/thread-648-1-1.html

http://v.youku.com/v_show/id_XODY4NTA3OTcy.html?from=s1.8-1-1.2&spm=a2h0k.8191407.0.0

1. add configuration in dts

hello-led{compatible = "firefly,hello_led";led= <&gpio8 GPIO_A2 GPIO_ACTIVE_LOW>;status = "okay";};

2. source code

#include <linux/kernel.h>#include <linux/init.h>#include <linux/module.h> #include <linux/delay.h>#include <linux/gpio.h>#ifdef CONFIG_OF#include <linux/of.h>#include <linux/of_gpio.h>#include <linux/of_platform.h>#endif#define GPIO_LOW 0#define GPIO_HIGH 1static int firefly_hello_probe(struct platform_device *pdev){    int ret = -1;int i;    int gpio,flag;struct device_node *hello_node = pdev->dev.of_node;printk("%s-%d: enter\n",__FUNCTION__,__LINE__);gpio = of_get_named_gpio_flags(hello_node,"led", 0,&flag);if (!gpio_is_valid(gpio)){printk("hello: invalid gpio : %d\n",gpio);return -1;}     ret = gpio_request(gpio, "hello_led");if (ret != 0) {gpio_free(gpio);return -EIO;}gpio_direction_output(gpio, GPIO_HIGH);for(i=0; i < 10; i++){gpio_set_value(gpio,GPIO_LOW);mdelay(500);gpio_set_value(gpio,GPIO_HIGH);mdelay(500);}    printk("%s-%d: exit\n",__FUNCTION__,__LINE__);return 0;  //return Ok}static int firefly_hello_remove(struct platform_device *pdev){     return 0;}#ifdef CONFIG_OFstatic const struct of_device_id of_firefly_hello_match[] = {{ .compatible = "firefly,hello_led" },{ /* Sentinel */ }};#endifstatic struct platform_driver firefly_hello_driver = {.probe= firefly_hello_probe,.remove= firefly_hello_remove,.driver= {.name= "firefly_hello",.owner= THIS_MODULE,#ifdef CONFIG_OF.of_match_table= of_firefly_hello_match,#endif},};static int __init hello_init(void){    printk(KERN_INFO "Enter %s\n", __FUNCTION__);    return platform_driver_register(&firefly_hello_driver);    return 0;}static void __exit hello_exit(void){platform_driver_unregister(&firefly_hello_driver);    printk("Exit Hello world\n");}subsys_initcall(hello_init);module_exit(hello_exit);MODULE_AUTHOR("sai <271319925@qq.com>");MODULE_DESCRIPTION("Firefly hello driver");MODULE_LICENSE("GPL");

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