#include <linux/module.h>
#include <asm/addrspace.h>
#include <asm/byteorder.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/io.h>
#include <linux/rmap.h>
#include <asm/tlbflush.h>

/*--------------------------------------------------------------------------------*\
 * writep(un)protect virt_addr-area 
 * ret: 0 ok
\*--------------------------------------------------------------------------------*/
int __io_remap_setwriteprotect(unsigned char *virt_addr, unsigned int len, unsigned int wrprotect) {
    unsigned char *end_virt_addr = virt_addr + len;
    /*--- printk("%s(%p,%d,%d)\n", __func__, virt_addr, len, wrprotect); ---*/
    
	flush_cache_all();

    while(virt_addr < end_virt_addr) {
        spinlock_t *ptl;
        pte_t *pte;
        struct page *_page;
        _page = vmalloc_to_page(virt_addr);

        pte = page_check_address(_page, &init_mm, (unsigned long)virt_addr, &ptl, 1);
        if(pte == NULL) {
            printk(KERN_DEBUG"%s: info: no pte for addr %p\n", __func__, virt_addr);
            return 1;
        }
        if(wrprotect) {
            ptep_set_wrprotect(&init_mm, (unsigned int)virt_addr, pte);
        } else {
            pte_t old_pte = *pte;
            set_pte_at(&init_mm, virt_addr, pte, pte_mkwrite(old_pte));
        }
        pte_unmap_unlock(pte, ptl);
        virt_addr += PAGE_SIZE;
    }
	flush_tlb_all();
    return 0;
}
EXPORT_SYMBOL(__io_remap_setwriteprotect);