at91sam9x5 linux 4.1.0下dts驱动编程模型

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");