Kernel Module to turn GPIO1_6 on and off

gistfile1.c

#include <linux/module.h>       /* Needed by all modules */
#include <linux/kernel.h>       /* Needed for KERN_INFO */
#include <linux/init.h>         /* Needed for the macros */
#include <plat/gpio.h>
#include <plat/am33xx.h>
#include <asm/io.h>

#define DEVICE_NAME "led_drv"

static __iomem unsigned char *gpio1_start;

static int __init hello_start(void)
{
        unsigned int value;
        unsigned long flags = 0;
        printk(KERN_INFO "Lights on\n");
        
        request_mem_region (AM33XX_GPIO1_BASE, 0x1000, DEVICE_NAME);

	/* Map io memory */
	gpio1_start = ioremap(AM33XX_GPIO1_BASE, 0x1000);
	if (gpio1_start == NULL) {
		printk ("Cannot map memory\n");
		return -EIO;
	}
        
        local_irq_save(flags);
        /* Set the 6th bit in the output enable to turn the GPIO into an output */
        value = __raw_readl(gpio1_start + OMAP4_GPIO_OE);
        value &= ~(1 << 6);
        __raw_writel(value, gpio1_start + OMAP4_GPIO_OE);
        /* Set the pin to a 1 in setdataout to turn on */ 
        value = __raw_readl(gpio1_start + OMAP4_GPIO_SETDATAOUT);
        value |= 1 << 6;
        __raw_writel(value, gpio1_start + OMAP4_GPIO_SETDATAOUT);
        
        local_irq_restore(flags);
        return 0;
}

static void __exit hello_end(void)
{
        unsigned int value;
        unsigned long flags = 0;
        local_irq_save(flags);
        /* Set the pin to a 1 in cleardataout to turn it off */
        value = __raw_readl(gpio1_start + OMAP4_GPIO_CLEARDATAOUT);
        value |= 1 << 6;
        __raw_writel(value, gpio1_start + OMAP4_GPIO_CLEARDATAOUT);
        
        local_irq_restore(flags);
        iounmap (gpio1_start);
	release_mem_region (AM33XX_GPIO1_BASE, 0x1000);
        printk(KERN_INFO "Lights off\n");
}

module_init(hello_start);
module_exit(hello_end);

MODULE_LICENSE("GPL");