Linux Kernel Module to interface with GPIO module on Beaglebone Black - c

Question

I write a Linux kernel module on Beaglebone Black to interface with GPIO module use its registers. A button connect with GPIO20, a LED connect with GPIO30 via a transistor 200 Ohm. I want when insmod kernel module then press button, LED ON and press again LED OFF, and so on. Following is my code for kernel module. My problem is when press button, LED not switch state.
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
#include <linux/io.h>
#include <linux/delay.h>
#define GPIO_ADDR_BASE 0X44E07000
#define ADDR_SIZE 0X1000
#define GPIO_SETDATAOUT_OFFSET 0X194
#define GPIO_CLEARDATAOUT_OFFSET 0X190
#define GPIO_OE_OFFSET 0X134
#define GPIO_DATAIN_OFFSET 0X138
// enable IRQ
#define GPIO_IRQSTATUS_RAW_0_OFFSET 0X24
// enable interrupt
#define GPIO_IRQSTATUS_SET_0_OFFSET 0X34
// define intterupt type
#define GPIO_RISINGDETECT_OFFSET 0X148
// enable debounce feature
#define GPIO_DEBOUNCENABLE_OFFSET 0X150
// set debounce time
#define GPIO_DEBOUNCINGTIME_OFFSET 0X154
#define LED_VALUE_0 ~(1 << 30)
#define LED_VALUE_1 (1 << 30)
#define BUTTON_VALUE_0 ~(1 << 20)
#define BUTTON_VALUE_1 (1 << 20)
void __iomem *base_addr;
int init_module(void)
{
uint32_t reg_data = 0;
printk(KERN_EMERG "Hello");
base_addr = ioremap(GPIO_ADDR_BASE, ADDR_SIZE);
// CONFIG for LED
/* write 0 to GPIO Pin 30 mean config this pin is output */
writel_relaxed(LED_VALUE_0, base_addr + GPIO_OE_OFFSET);
// at insert module time, led off
writel_relaxed(LED_VALUE_1, base_addr + GPIO_CLEARDATAOUT_OFFSET);
// CONFIG for BUTTON
// config button pin is GPIO input
writel_relaxed(BUTTON_VALUE_1, base_addr + GPIO_OE_OFFSET);
// active IRQ
writel_relaxed(0x1, base_addr + GPIO_IRQSTATUS_RAW_0_OFFSET);
// enable interrupt
writel_relaxed(0x1, base_addr + GPIO_IRQSTATUS_SET_0_OFFSET);
// enable rising interrupt
writel_relaxed(0x1, base_addr + GPIO_RISINGDETECT_OFFSET);
// enable debounce feature
writel_relaxed(1 << 20, base_addr + GPIO_DEBOUNCENABLE_OFFSET);
// set debounce time
writel_relaxed(0xFF, base_addr + GPIO_DEBOUNCINGTIME_OFFSET);
while (1) {
reg_data = readl_relaxed(base_addr + GPIO_DATAIN_OFFSET);
if (reg_data == 1)
{
writel_relaxed(LED_VALUE_1, base_addr + GPIO_SETDATAOUT_OFFSET);
mdelay(1000);
}
}
return 0;
}
void cleanup_module(void)
{
printk(KERN_EMERG "Goodbye");
/* off led */
writel_relaxed(LED_VALUE_1, base_addr + GPIO_CLEARDATAOUT_OFFSET);
/* config default GPIO Pin is input
* set Pin 30 to default
*/
writel_relaxed(LED_VALUE_1, base_addr + GPIO_CLEARDATAOUT_OFFSET);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Phu Luu An");
MODULE_DESCRIPTION("Hello world kernel module");