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
13static unsigned long mmio_address;
14module_param_hw(mmio_address, ulong, iomem, 0);
15MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
16				"(or 8 MB if read_far is non-zero).");
17
18static unsigned long read_far = 0x400100;
19module_param(read_far, ulong, 0);
20MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
21				"(default: 0x400100).");
22
23static unsigned v16(unsigned i)
24{
25	return i * 12 + 7;
26}
27
28static unsigned v32(unsigned i)
29{
30	return i * 212371 + 13;
31}
32
33static 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
49static 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
72static 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
80static 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 */
101static 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
116static 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
139static void __exit cleanup(void)
140{
141	pr_debug("unloaded.\n");
142}
143
144module_init(init);
145module_exit(cleanup);
146MODULE_LICENSE("GPL");
147