/*
 *  mx21_gpio.c
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/ioport.h>

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
#include <linux/wrapper.h>
#endif

#define INTERRUPT 107

#define mx21gpio_VERSION "1.0"
#define mx21gpio_MAJOR 240
#define mx21gpio_NAME "gpio"

#define GPIO_BASE 0x10015000
#define GPIO_MASK 0x00000fff
#define GPIO_SIZE 0x600

#define GPIOB_DDIR 64 
#define GPIOB_OCR1 65 
#define GPIOB_DATA 71 
#define GPIOB_GIUS 72 
#define GPIOB_IMR  76 

#define GPIO_VAL_DDIR 0x00000400
#define GPIO_VAL_OCR1 0x00F00000
#define GPIO_VAL_D1   0x00000400
#define GPIO_VAL_D0   0x00000000
#define GPIO_VAL_GIUS 0x00000C00
#define GPIO_VAL_IMR  0x00000800

#define COMMAND_MASK 0x80000000
#undef DEBUG

volatile unsigned int *gpio_ptr;
unsigned int offset;
int interruptcount = 0;
static struct proc_dir_entry *interrupt_arm_file;
static struct fasync_struct *fasync_mx21_queue ;

DECLARE_WAIT_QUEUE_HEAD(mx21gpio_wait);

void interrupt_interrupt_arm(int irq, void *dev_id, struct pt_regs *regs)
{

   interruptcount++;
   printk(KERN_INFO "\nmx21_gpio: Interrupt detected in kernel \n");

   /* Signal the user application that an interupt occured */
   kill_fasync(&fasync_mx21_queue, SIGIO, POLL_IN);

}

static int proc_read_interrupt_arm(char *page, char **start, off_t off, int count, int *eof, void *data)
{
  int len;

  len = sprintf(page, "Total number of interrupts %19i\n", interruptcount);

  return len;
}

static int mx21gpio_open1 (struct inode *inode, struct file *file) {
   return 0;
}

static int mx21gpio_release1 (struct inode *inode, struct file *file) {
   return 0;
}

static int mx21gpio_fasync1 (int fd, struct file *filp, int on)
{

   printk(KERN_INFO "\nmx21_gpio: Inside mx21_fasync \n");
   return fasync_helper(fd, filp, on, &fasync_mx21_queue);

} 

static int mx21gpio_ioctl1(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) {

   int retval = 0;
   int input;
   unsigned long value;
   unsigned int command_type;
   unsigned int offset;
   volatile unsigned int *access_addr;

   command_type = 0x80000000ul;

   // Set the offset for register accesses
   command_type = COMMAND_MASK & cmd;

   offset = ~COMMAND_MASK & cmd & GPIO_MASK;
   if(offset > GPIO_SIZE)
      retval=-EINVAL;

   switch(command_type)
   {
      case 0:
         //read
         if(!access_ok(VERIFY_READ, (unsigned int *)arg, sizeof(int)))
            return -EFAULT;

         *(unsigned int *)arg = readl((volatile unsigned int *)&gpio_ptr[offset]);
         break;

      case COMMAND_MASK:
         //write
         access_addr = gpio_ptr + GPIOB_DATA;
         input = *(unsigned int *)arg;

         if(!access_ok(VERIFY_WRITE, (unsigned int *)arg, sizeof(int)))
            return -EFAULT;

         if (input == 1001)
         {
            // Assert PB10
            value = GPIO_VAL_D1;
            printk("\nmx21-1001: Write value %08x to GPIO\n", (unsigned int)value);
            writel(value, access_addr); 
            // writel(*(unsigned int *)value,(volatile unsigned int *)access_addr); 
         }
         if (input == 1000)
         {
            // Deassert PB10
            value = GPIO_VAL_D0;
            printk("\nmx21-1000: Write value %08x to GPIO\n", (unsigned int)value);
            writel(value, access_addr); 
            // writel(*(unsigned int *)value,(volatile unsigned int *)access_addr); 
         }          
         break;

      default:
         retval = -EINVAL;
   }

   return retval;
}

// define which file operations are supported
struct file_operations mx21gpio_fops = {
   .owner=   THIS_MODULE,
   .llseek  = NULL,
   .read    = NULL,
   .write   = NULL,
   .readdir = NULL,
   .poll    = NULL,
   .ioctl   = mx21gpio_ioctl1,
   .mmap    = NULL,
   .open    = mx21gpio_open1,
   .flush   = NULL,
   .release = mx21gpio_release1,
   .fsync   = NULL,
   .fasync  = mx21gpio_fasync1,
   .lock    = NULL,
   .readv   = NULL,
   .writev  = NULL,
};

// initialize module
static int __init mx21gpio_init_module (void) {

   int rv = 0;
   unsigned long arg = 0;
   volatile unsigned int *access_addr;

   printk("i.MX21 GPIO Interface Module\n");
   printk(KERN_INFO "\nmx21_gpio: i.MX21 GPIO Driver Loading.\n");
   printk(KERN_INFO "mx21_gpio: Using Major Number %d on %s\n", mx21gpio_MAJOR, mx21gpio_NAME); 

   if (register_chrdev(mx21gpio_MAJOR, mx21gpio_NAME, &mx21gpio_fops)) 
   {
      printk("mx21_gpio: unable to get major %d. ABORTING!\n", mx21gpio_MAJOR);
      return -EBUSY;
   }

   // Perform Memory REMAP
   if (check_mem_region(GPIO_BASE, GPIO_SIZE))
   {
      printk(KERN_ERR "mx21_gpio: Unable to acquire GPIO address.\n");
      return -EBUSY;
   }

   request_mem_region(GPIO_BASE, GPIO_SIZE, mx21gpio_NAME);
   gpio_ptr = (volatile unsigned int *)__ioremap(GPIO_BASE, GPIO_SIZE, 0);

   if (!gpio_ptr)
   {
      printk(KERN_ERR "mx21_gpio: Unable to map GPIO.\n");
      release_mem_region(GPIO_BASE, GPIO_SIZE);

      return -EBUSY;
   }

   printk("mx21_gpio: %08x size %08x mapped to %08x\n", GPIO_BASE, GPIO_SIZE, (unsigned int)gpio_ptr);

   // Set Direction register on PB10 = output, PB11 = input
   access_addr = gpio_ptr + GPIOB_DDIR;
   arg = readl(access_addr);
   arg = arg | GPIO_VAL_DDIR;
   writel(arg, access_addr); 

   // Set OCR1 Register
   access_addr = gpio_ptr + GPIOB_OCR1;
   arg = readl((volatile unsigned int *)access_addr);
   arg = arg | GPIO_VAL_OCR1;
   writel(arg, access_addr); 

   // Set GIUS Register 
   access_addr = gpio_ptr + GPIOB_GIUS;
   arg = readl(access_addr);
   arg = arg | GPIO_VAL_GIUS;
   writel(arg, access_addr); 

   // Set IMR Register 
   access_addr = gpio_ptr + GPIOB_IMR;
   arg = readl(access_addr);
   arg = arg | GPIO_VAL_IMR;
   writel(arg, access_addr); 

   interrupt_arm_file = create_proc_entry("interrupt_arm", 0444, NULL);

   if(interrupt_arm_file == NULL)
   {
      printk("mx21_gpio: create /proc entry returned NULL. ABORTING!\n");
      return -ENOMEM;
   }

   interrupt_arm_file->data = NULL;
   interrupt_arm_file->read_proc = &proc_read_interrupt_arm;
   interrupt_arm_file->write_proc = NULL;
   interrupt_arm_file->owner = THIS_MODULE;

   /* request interrupt from linux */
   rv = request_irq(INTERRUPT, interrupt_interrupt_arm, SA_TRIGGER_RISING, "interrupt_arm", NULL);
  
   if ( rv )
   {
      printk("mx21_gpio: Can't get interrupt %d\n", INTERRUPT);
      goto no_interrupt_arm;
   }

   /* everything initialized */
   printk(KERN_INFO "mx21_gpio: %s %s Initialized\n", mx21gpio_NAME, mx21gpio_VERSION);
   return 0;

   /* remove the proc entry on error */
   no_interrupt_arm:
   remove_proc_entry("interrupt_arm", NULL);
   return -EBUSY;

}

static void __exit mx21gpio_cleanup_module (void) {

   free_irq(INTERRUPT,NULL);

   iounmap((void *)gpio_ptr);
   release_mem_region(GPIO_BASE, GPIO_SIZE);
   printk("mx21_gpio: Device released.\n");

   unregister_chrdev (mx21gpio_MAJOR, mx21gpio_NAME);

   remove_proc_entry("interrupt_arm", NULL);
   printk(KERN_INFO "mx21_gpio: %s %s removed\n", mx21gpio_NAME, mx21gpio_VERSION);

}

module_init(mx21gpio_init_module);
module_exit(mx21gpio_cleanup_module);
MODULE_AUTHOR("tarun@virtualcogs.com");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("iMX21 GPIO Device Driver");