Driver Debug : sparse

apt-get install sparse


以此範例來說如果直接make是看不出記指標任何錯誤 ex: http://kingofsdtw.blogspot.tw/2015/02/blog-post.html#links
\> make
if do make ,can't find any pointer error

安裝 sparse，並用 __iomem 監視你要的pointer
after install sparse and use __iomem monitor your pointer
( __iomem only useful when install sparse )
\> make C=2


他會幫助你發現錯誤
It will help you find some error


 BUG:

//
//-------------------------------------------//
// FUNCTION   : MMIO_TEST
// INPUT      : 
// OUTPUT     :
// DESCRIPTION: 
//
// #include 
// size : byte
// ioremap(unsigned long phy_addr , unsigned int size)
// ioremap_nocache(unsigned long phy_addr , unsigned int size)
// iounmap()
// release_mem_regin( start , size);
//-------------------------------------------//
//
void MMIO_TEST(void){
  char __iomem *reg;
  

  reg = ioremap_nocache(0xFEC00000 , 4 );
  if(reg != NULL)
   {
    
     printk("Get mmio ,data = 0x%x\n",*reg);
     
     //free
     iounmap(reg); 
   }
 
 }

Fix:

//
//-------------------------------------------//
// FUNCTION   : MMIO_TEST
// INPUT      : 
// OUTPUT     :
// DESCRIPTION: 
//
// #include 
// size : byte
// ioremap(unsigned long phy_addr , unsigned int size)
// ioremap_nocache(unsigned long phy_addr , unsigned int size)
// iounmap()
// release_mem_regin( start , size);
//-------------------------------------------//
//
void MMIO_TEST(void){
  char __iomem *reg;
  

  reg = ioremap_nocache(0xFEC00000 , 4 );
  if(reg != NULL)
   {
    
     printk("Get mmio ,data = 0x%x\n",ioread8(reg));
     
     //free
     iounmap(reg); 
   }
 
 
 
 }