1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
4 */
5
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8 #include <linux/module.h>
9 #include <linux/io.h>
10 #include <linux/mmiotrace.h>
11 #include <linux/security.h>
12
13 static unsigned long mmio_address;
14 module_param_hw(mmio_address, ulong, iomem, 0);
15 MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
16 "(or 8 MB if read_far is non-zero).");
17
18 static unsigned long read_far = 0x400100;
19 module_param(read_far, ulong, 0);
20 MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
21 "(default: 0x400100).");
22
23 static unsigned v16(unsigned i)
24 {
25 return i * 12 + 7;
26 }
27
28 static unsigned v32(unsigned i)
29 {
30 return i * 212371 + 13;
31 }
32
33 static void do_write_test(void __iomem *p)
34 {
35 unsigned int i;
36 pr_info("write test.\n");
37 mmiotrace_printk("Write test.\n");
38
39 for (i = 0; i < 256; i++)
40 iowrite8(i, p + i);
41
42 for (i = 1024; i < (5 * 1024); i += 2)
43 iowrite16(v16(i), p + i);
44
45 for (i = (5 * 1024); i < (16 * 1024); i += 4)
46 iowrite32(v32(i), p + i);
47 }
48
49 static void do_read_test(void __iomem *p)
50 {
51 unsigned int i;
52 unsigned errs[3] = { 0 };
53 pr_info("read test.\n");
54 mmiotrace_printk("Read test.\n");
55
56 for (i = 0; i < 256; i++)
57 if (ioread8(p + i) != i)
58 ++errs[0];
59
60 for (i = 1024; i < (5 * 1024); i += 2)
61 if (ioread16(p + i) != v16(i))
62 ++errs[1];
63
64 for (i = (5 * 1024); i < (16 * 1024); i += 4)
65 if (ioread32(p + i) != v32(i))
66 ++errs[2];
67
68 mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
69 errs[0], errs[1], errs[2]);
70 }
71
72 static void do_read_far_test(void __iomem *p)
73 {
74 pr_info("read far test.\n");
75 mmiotrace_printk("Read far test.\n");
76
77 ioread32(p + read_far);
78 }
79
80 static void do_test(unsigned long size)
81 {
82 void __iomem *p = ioremap(mmio_address, size);
83 if (!p) {
84 pr_err("could not ioremap, aborting.\n");
85 return;
86 }
87 mmiotrace_printk("ioremap returned %p.\n", p);
88 do_write_test(p);
89 do_read_test(p);
90 if (read_far && read_far < size - 4)
91 do_read_far_test(p);
92 iounmap(p);
93 }
94
95 /*
96 * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
97 * a short time. We had a bug in deferred freeing procedure which tried
98 * to free this region multiple times (ioremap can reuse the same address
99 * for many mappings).
100 */
101 static void do_test_bulk_ioremapping(void)
102 {
103 void __iomem *p;
104 int i;
105
106 for (i = 0; i < 10; ++i) {
107 p = ioremap(mmio_address, PAGE_SIZE);
108 if (p)
109 iounmap(p);
110 }
111
112 /* Force freeing. If it will crash we will know why. */
113 synchronize_rcu();
114 }
115
116 static int __init init(void)
117 {
118 unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
119 int ret = security_locked_down(LOCKDOWN_MMIOTRACE);
120
121 if (ret)
122 return ret;
123
124 if (mmio_address == 0) {
125 pr_err("you have to use the module argument mmio_address.\n");
126 pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
127 return -ENXIO;
128 }
129
130 pr_warn("WARNING: mapping %lu kB @ 0x%08lx in PCI address space, "
131 "and writing 16 kB of rubbish in there.\n",
132 size >> 10, mmio_address);
133 do_test(size);
134 do_test_bulk_ioremapping();
135 pr_info("All done.\n");
136 return 0;
137 }
138
139 static void __exit cleanup(void)
140 {
141 pr_debug("unloaded.\n");
142 }
143
144 module_init(init);
145 module_exit(cleanup);
146 MODULE_LICENSE("GPL");
147
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