GPIO1_7 interrupt driven

gistfile1.txt

#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 <linux/interrupt.h>
#include <linux/irq.h>
#include <plat/gpio.h>
#include <asm/gpio.h>
#include <plat/am33xx.h>
#include <asm/io.h>

#define DEVICE_NAME                             "led_drv"
#define GPIO1_7                                 39  /* (chip_num * 32) + pin */
#define PIN_POS                                 7
#define AM33XX_CONTROL_PADCONF_MUX_PBASE		0x44E10000LU

static __iomem unsigned char *gpio1_start;
static __iomem unsigned char *control_module_start;

static irqreturn_t hello_irq_handler (int irq, void *dev_id)
{
    printk (KERN_INFO "INTERRUPT!\n");
    return IRQ_HANDLED;
}

static int __init hello_start(void)
{
    int ret;
    unsigned int value;
    unsigned long flags = 0;
    printk(KERN_INFO "Hello world\n");
    
    /* Get access to the GPIO */
    request_mem_region (AM33XX_GPIO1_BASE, 0x1000, DEVICE_NAME);
    /* Map io memory */
    gpio1_start = ioremap(AM33XX_GPIO1_BASE, 0x1000);
    if (gpio1_start == NULL)
    {
        printk (KERN_INFO "Cannot map GPIO memory\n");
        return -EIO;
    }
    
    /* Get access to the Control Module */
    request_mem_region (AM33XX_CONTROL_PADCONF_MUX_PBASE, 0x1000, DEVICE_NAME);
    /* Map io memory */
    control_module_start = ioremap(AM33XX_CONTROL_PADCONF_MUX_PBASE, 0x1000);
    if (control_module_start == NULL)
    {
        printk (KERN_INFO "Cannot map control module memory\n");
        return -EIO;
    }

    {
        /* Configure the GPIO to be an input */
        local_irq_save(flags);
        value = __raw_readl(gpio1_start + OMAP4_GPIO_OE);
        value |= 1 << PIN_POS;
        __raw_writel(value, gpio1_start + OMAP4_GPIO_OE);

        value = __raw_readl(gpio1_start + OMAP4_GPIO_SETDATAOUT);
        value |= 1 << PIN_POS;
        __raw_writel(value, gpio1_start + OMAP4_GPIO_SETDATAOUT);

        local_irq_restore(flags);
    }
    
    {
        /* Set the control module pad stuff - gpmc_ad7 is at OFFSET 0x81c */
        /*
        Bit     Field           Type    Reset   Description
        31-20   Reserved        R       0x0     
        19-7    Reserved        R       0x0     
        6       conf_sle        R/W     0x0     Select between faster or slower slew rate
                                                0: Fast
                                                1: Slow
                                                Reset value is pad-dependent.
        5       conf_rx         R/W     0x1     Input Enable value for pad
                                                0: rx disabled
                                                1: rx enabled
        4       conf_putypesel  R/W     0x0     Pad pullup/pulldown type selection
                                                0: Pulldown
                                                1: Pullup
                                                Reset value is pad-dependent.
        3       conf_puden      R/W     0x0     Pad pullup/pulldown enable
                                                0: Pullup/Pulldown enabled
                                                1: Pullup/Pulldown disabled
                                                Reset value is pad-dependent.
        2-0     conf_m_mode     R/W     0x0     Pad functional signal mux select
                                                Reset value is pad-dependent.
       
        */
        /* If we were being a good citizen, we'd restore this =) */
        local_irq_save(flags);
        __raw_writel(0x27, control_module_start + 0x81c);
        value = __raw_readl(control_module_start + 0x81c);
        local_irq_restore(flags);
    }
    if (0x27 != value)
    {
        printk (KERN_INFO "Couldn't set value, expected 0x27 but got 0x%x - " \
            "Exiting\n", value);
        
        iounmap(gpio1_start);
        release_mem_region(AM33XX_GPIO1_BASE, 0x1000);
        
        iounmap(control_module_start);
        release_mem_region(AM33XX_CONTROL_PADCONF_MUX_PBASE, 0x1000);
        return -EIO;
    }
    
    
    /* Get the IRQ value */
    ret = gpio_to_irq(GPIO1_7);

    /* Install interrupt handler */
    ret = request_irq(ret, hello_irq_handler, IRQF_TRIGGER_RISING, 
        "hello-int", NULL);
    if (ret != 0 )
    {
        printk (KERN_INFO "Error: request_irq returned %d\n", ret);
        return -EIO;
    }
	
    return 0;
}

static void __exit hello_end(void)
{
    free_irq (gpio_to_irq(GPIO1_7), NULL);
    iounmap (gpio1_start);
    release_mem_region (AM33XX_GPIO1_BASE, 0x1000);
    
    iounmap (control_module_start);
    release_mem_region (AM33XX_CONTROL_PADCONF_MUX_PBASE, 0x1000);
    printk(KERN_INFO "Goodbye World\n");
}

module_init(hello_start);
module_exit(hello_end);
MODULE_AUTHOR("Nick Glynn <nick.glynn@feabhas.com>");
MODULE_LICENSE("GPL");