arch/x86/mm/testmmiotrace.c

   1 /*
   2  * Written by Pekka Paalanen, 2008 <pq@iki.fi>
   3  */
   4 #include <linux/module.h>
   5 #include <linux/io.h>
   6
   7 #define MODULE_NAME "testmmiotrace"
   8
   9 static unsigned long mmio_address;
  10 module_param(mmio_address, ulong, 0);
  11 MODULE_PARM_DESC(mmio_address, "Start address of the mapping of 16 kB.");
  12
  13 static void do_write_test(void __iomem *p)
  14 {
  15         unsigned int i;
  16         for (i = 0; i < 256; i++)
  17                 iowrite8(i, p + i);
  18         for (i = 1024; i < (5 * 1024); i += 2)
  19                 iowrite16(i * 12 + 7, p + i);
  20         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  21                 iowrite32(i * 212371 + 13, p + i);
  22 }
  23
  24 static void do_read_test(void __iomem *p)
  25 {
  26         unsigned int i;
  27         for (i = 0; i < 256; i++)
  28                 ioread8(p + i);
  29         for (i = 1024; i < (5 * 1024); i += 2)
  30                 ioread16(p + i);
  31         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  32                 ioread32(p + i);
  33 }
  34
  35 static void do_test(void)
  36 {
  37         void __iomem *p = ioremap_nocache(mmio_address, 0x4000);
  38         if (!p) {
  39                 pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
  40                 return;
  41         }
  42         do_write_test(p);
  43         do_read_test(p);
  44         iounmap(p);
  45 }
  46
  47 static int __init init(void)
  48 {
  49         if (mmio_address == 0) {
  50                 pr_err(MODULE_NAME ": you have to use the module argument "
  51                                                         "mmio_address.\n");
  52                 pr_err(MODULE_NAME ": DO NOT LOAD THIS MODULE UNLESS"
  53                                 " YOU REALLY KNOW WHAT YOU ARE DOING!\n");
  54                 return -ENXIO;
  55         }
  56
  57         pr_warning(MODULE_NAME ": WARNING: mapping 16 kB @ 0x%08lx "
  58                                         "in PCI address space, and writing "
  59                                         "rubbish in there.\n", mmio_address);
  60         do_test();
  61         return 0;
  62 }
  63
  64 static void __exit cleanup(void)
  65 {
  66         pr_debug(MODULE_NAME ": unloaded.\n");
  67 }
  68
  69 module_init(init);
  70 module_exit(cleanup);
  71 MODULE_LICENSE("GPL");