gpio.c

此程序是在linux操作系统下的GPIO驱动

/* gpio.c
 *东南大学嵌入式工程中心
 *
*/


#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <asm/hardware.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/delay.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>

#define W90X900_GPIOE_DIR   (W90X900_VA_GPIO + 0x44)
#define W90X900_GPIOE_DOUT  (W90X900_VA_GPIO + 0x48)
#define W90X900_GPIOE_DIN   (W90X900_VA_GPIO + 0x4C)
#define W90X900_MFSEL       (W90X900_VA_GCR + 0x0C)

static struct platform_device *sys_gpio;

static ssize_t write_gpio(struct device *dev, struct device_attribute *attr, const char *buffer, size_t count)
{
  
    if(buffer[0] == '0') { 
	outl(inl(W90X900_GPIOE_DOUT) & ~0x40, W90X900_GPIOE_DOUT);
    } else if(buffer[0] == '1') {
        outl(inl(W90X900_GPIOE_DOUT) | 0x40, W90X900_GPIOE_DOUT);
    } 

    return count;
}

static ssize_t read_gpio(struct device *dev, struct device_attribute *attr, char *buf)
{
    unsigned int i;

    i = inl(W90X900_GPIOE_DIN) & 0x80;
    i >>= 7;

    return sprintf(buf, "%01x\n", i);
}    
/* Attach the sysfs write method */
DEVICE_ATTR(gpio, 0644, read_gpio, write_gpio);

/* Attribute Descriptor */
static struct attribute *gpio_attrs[] = {
  &dev_attr_gpio.attr,
  NULL
};

/* Attribute group */
static struct attribute_group gpio_attr_group = {
  .attrs = gpio_attrs,
};

static int __init w90x900_gpio_demo(void)
{
    /* Register a platform device */
    printk("register gpio device\n");
  
    // Set GPIOE6 as output, GPIOE7 as input
    outl(inl(W90X900_MFSEL) & ~0x400,W90X900_MFSEL);
    outl(inl(W90X900_GPIOE_DIR) & ~0x80,W90X900_GPIOE_DIR);
    outl(inl(W90X900_GPIOE_DIR) | 0x40,W90X900_GPIOE_DIR);

    sys_gpio = platform_device_register_simple("w90x900-gpio", -1, NULL, 0);    
    if(sys_gpio == NULL)
    printk("register failed\n");
    sysfs_create_group(&sys_gpio->dev.kobj, &gpio_attr_group);
    
    return(0); 
}    

module_init(w90x900_gpio_demo);