arch/x86/mm/testmmiotrace.c

   1 /*
   2  * Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
   3  */
   4
   5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   6
   7 #include <linux/module.h>
   8 #include <linux/io.h>
   9 #include <linux/mmiotrace.h>
  10
  11 static unsigned long mmio_address;
  12 module_param(mmio_address, ulong, 0);
  13 MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
  14                                 "(or 8 MB if read_far is non-zero).");
  15
  16 static unsigned long read_far = 0x400100;
  17 module_param(read_far, ulong, 0);
  18 MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
  19                                 "(default: 0x400100).");
  20
  21 static unsigned v16(unsigned i)
  22 {
  23         return i * 12 + 7;
  24 }
  25
  26 static unsigned v32(unsigned i)
  27 {
  28         return i * 212371 + 13;
  29 }
  30
  31 static void do_write_test(void __iomem *p)
  32 {
  33         unsigned int i;
  34         pr_info("write test.\n");
  35         mmiotrace_printk("Write test.\n");
  36
  37         for (i = 0; i < 256; i++)
  38                 iowrite8(i, p + i);
  39
  40         for (i = 1024; i < (5 * 1024); i += 2)
  41                 iowrite16(v16(i), p + i);
  42
  43         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  44                 iowrite32(v32(i), p + i);
  45 }
  46
  47 static void do_read_test(void __iomem *p)
  48 {
  49         unsigned int i;
  50         unsigned errs[3] = { 0 };
  51         pr_info("read test.\n");
  52         mmiotrace_printk("Read test.\n");
  53
  54         for (i = 0; i < 256; i++)
  55                 if (ioread8(p + i) != i)
  56                         ++errs[0];
  57
  58         for (i = 1024; i < (5 * 1024); i += 2)
  59                 if (ioread16(p + i) != v16(i))
  60                         ++errs[1];
  61
  62         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  63                 if (ioread32(p + i) != v32(i))
  64                         ++errs[2];
  65
  66         mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
  67                                                 errs[0], errs[1], errs[2]);
  68 }
  69
  70 static void do_read_far_test(void __iomem *p)
  71 {
  72         pr_info("read far test.\n");
  73         mmiotrace_printk("Read far test.\n");
  74
  75         ioread32(p + read_far);
  76 }
  77
  78 static void do_test(unsigned long size)
  79 {
  80         void __iomem *p = ioremap_nocache(mmio_address, size);
  81         if (!p) {
  82                 pr_err("could not ioremap, aborting.\n");
  83                 return;
  84         }
  85         mmiotrace_printk("ioremap returned %p.\n", p);
  86         do_write_test(p);
  87         do_read_test(p);
  88         if (read_far && read_far < size - 4)
  89                 do_read_far_test(p);
  90         iounmap(p);
  91 }
  92
  93 /*
  94  * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
  95  * a short time. We had a bug in deferred freeing procedure which tried
  96  * to free this region multiple times (ioremap can reuse the same address
  97  * for many mappings).
  98  */
  99 static void do_test_bulk_ioremapping(void)
 100 {
 101         void __iomem *p;
 102         int i;
 103
 104         for (i = 0; i < 10; ++i) {
 105                 p = ioremap_nocache(mmio_address, PAGE_SIZE);
 106                 if (p)
 107                         iounmap(p);
 108         }
 109
 110         /* Force freeing. If it will crash we will know why. */
 111         synchronize_rcu();
 112 }
 113
 114 static int __init init(void)
 115 {
 116         unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
 117
 118         if (mmio_address == 0) {
 119                 pr_err("you have to use the module argument mmio_address.\n");
 120                 pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
 121                 return -ENXIO;
 122         }
 123
 124         pr_warning("WARNING: mapping %lu kB @ 0x%08lx in PCI address space, "
 125                    "and writing 16 kB of rubbish in there.\n",
 126                    size >> 10, mmio_address);
 127         do_test(size);
 128         do_test_bulk_ioremapping();
 129         pr_info("All done.\n");
 130         return 0;
 131 }
 132
 133 static void __exit cleanup(void)
 134 {
 135         pr_debug("unloaded.\n");
 136 }
 137
 138 module_init(init);
 139 module_exit(cleanup);
 140 MODULE_LICENSE("GPL");