测试环境： CPU: AT91SAM9X35 Linux: Atmel提供的linux-at91-linux4sam_5.3 (Linux-4.1.0)
转载请注明： 凌云物网智科嵌入式实验室： http://iot-yun.com/ 郭文学<guowenxue@gmail.com>
下面的这个驱动文件at91_keyled.c在Atmel提供的linux-at91-linux4sam_5.3下实现了按键控制LED的亮灭过程，通过这个简单的驱动描述了基于DTS的驱动开发模型以及Linux内核里的GPIO相关的操作函数。
/*********************************************************************************
* Copyright: (C) 2016 Guo Wenxue<guowenxue@gmail.com>
* All rights reserved.
*
* Filename: at91_keyled.c
* Description: This is a sample driver for GPIO operation with DTS linux on at91,
* which willl turn led on when a button pressed.
*
* Version: 1.0.0(2016-6-29~)
* Author: Guo Wenxue <guowenxue@gmail.com>
* ChangeLog: 1, Release initial version on "Wed Jun 29 12:00:44 CST 2016"
*
*
* DTS Changes:
* add keyleds support in arch/arm/boot/dts/at91sam9x5cm.dtsi
*
* keyleds{
* compatible = "key-leds";
* gpios = <&pioB 18 GPIO_ACTIVE_LOW priv->pin_key=of_get_gpio(pdev->dev.of_node, 0);
* &pioB 16 GPIO_ACTIVE_LOW>; priv->pin_key=of_get_gpio(pdev->dev.of_node, 1);
* status = "okay";
* }
*
* 1wire_cm {
* ... ...
* ... ...
* }
*
********************************************************************************/ #include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h> #include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/interrupt.h> typedef struct keyled_priv_s
{
int pin_key;
int pin_led;
int led_status;
} keyled_priv_t; /*--- end of struct keyled_priv_s ---*/ static const struct of_device_id of_key_leds_match[] = {
{ .compatible = "key-leds", },
{},
};
MODULE_DEVICE_TABLE(of, of_key_leds_match); static irqreturn_t key_detect_interrupt(int irq, void *dev_id)
{
keyled_priv_t *priv = (keyled_priv_t *)dev_id; priv->led_status ^= ;
gpio_set_value(priv->pin_led, priv->led_status); return IRQ_HANDLED;
} static int at91_keyled_probe(struct platform_device *pdev)
{
int res;
keyled_priv_t *priv; printk(KERN_INFO "at91_keyled driver probe\n"); if( != of_gpio_count(pdev->dev.of_node) )
{
printk(KERN_ERR "keyled pins definition in dts invalid\n");
return -EINVAL;
} priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if(!priv)
return -ENOMEM; platform_set_drvdata(pdev, priv); priv->pin_key=of_get_gpio(pdev->dev.of_node, );
priv->pin_led=of_get_gpio(pdev->dev.of_node, ); if( gpio_is_valid(priv->pin_key) )
{
if( (res=devm_gpio_request(&pdev->dev, priv->pin_key, "keyled_key")) < )
{
dev_err(&pdev->dev, "can't request key gpio %d\n", priv->pin_key);
return res;
}
dev_info(&pdev->dev, "request key gpio %d ok\n", priv->pin_key); if( (res=gpio_direction_input(priv->pin_key)) < )
{
dev_err(&pdev->dev, "can't request input direction key gpio %d\n", priv->pin_key);
return res;
}
dev_info(&pdev->dev, "request input direction key gpio %d ok\n", priv->pin_key); printk(KERN_INFO "Key gpio current status: %d\n", gpio_get_value(priv->pin_key)); res = request_irq( gpio_to_irq(priv->pin_key), key_detect_interrupt, IRQF_TRIGGER_FALLING, "keyled", priv);
if( res )
{
dev_err(&pdev->dev, "can't request IRQ<%d> for key gpio %d\n", gpio_to_irq(priv->pin_key), priv->pin_key);
return -EBUSY;
}
dev_info(&pdev->dev, "request IRQ<%d> for key gpio %d ok\n", gpio_to_irq(priv->pin_key), priv->pin_key);
} if( gpio_is_valid(priv->pin_led) )
{
if( (res=devm_gpio_request(&pdev->dev, priv->pin_led, "keyled_led")) < )
{
dev_err(&pdev->dev, "can't request key gpio %d\n", priv->pin_led);
return res;
} if( (res=gpio_direction_output(priv->pin_led, )) < )
{
dev_err(&pdev->dev, "can't request output direction key gpio %d\n", priv->pin_led);
return res;
}
} return ;
} static int at91_keyled_remove(struct platform_device *pdev)
{
keyled_priv_t *priv = platform_get_drvdata(pdev); printk(KERN_INFO "at91_keyled driver remove\n"); devm_gpio_free(&pdev->dev, priv->pin_led);
devm_gpio_free(&pdev->dev, priv->pin_key); free_irq(gpio_to_irq(priv->pin_key), priv); devm_kfree(&pdev->dev, priv); return ;
} static struct platform_driver at91_keyled_driver = {
.probe = at91_keyled_probe,
.remove = at91_keyled_remove,
.driver = {
.name = "key-leds",
.of_match_table = of_key_leds_match,
},
}; module_platform_driver(at91_keyled_driver); MODULE_AUTHOR("guowenxue <guowenxue@gmail.com>");
MODULE_DESCRIPTION("AT91 Linux DTS GPIO driver for Key and LED");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:key-leds");