#include <linux/kernel.h>
 #include <linux/module.h>

 static inline u32 armv6_sunavcr_read(void)
 {
     u32 val;

     asm volatile("mrc   p15, 0, %0, c15, c9, 0" : "=r"(val));
     return val;
 }

 static inline void armv6_sunavcr_write(u32 val)
 {
     asm volatile("mcr   p15, 0, %0, c15, c9, 0" : : "r"(val));
 }

 static int __init pmu_init(void)
 {
     u32 sunavcr = 0;

     armv6_sunavcr_write(0x1);
     sunavcr = armv6_sunavcr_read();

     if (sunavcr!=0) {
         printk("pmu_init(): userland acces to pmu-regs activated\n");
         return 0;
     } else {
         printk("pmu_init(): sunavcr_write() failed\n");
         return -EIO;
     }
 }

 static void __exit pmu_exit(void)
 {
     printk ("pmu_exit()\n");
     armv6_sunavcr_write(0x0);
 }

 module_init(pmu_init);
 module_exit(pmu_exit);

 MODULE_LICENSE("GPL");