1// SPDX-License-Identifier: GPL-2.0
2/*
3 * A dummy STM device for stm/stm_source class testing.
4 * Copyright (c) 2014, Intel Corporation.
5 *
6 * STM class implements generic infrastructure for  System Trace Module devices
7 * as defined in MIPI STPv2 specification.
8 */
9
10#undef DEBUG
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/stm.h>
15#include <uapi/linux/stm.h>
16
17static ssize_t notrace
18dummy_stm_packet(struct stm_data *stm_data, unsigned int master,
19		 unsigned int channel, unsigned int packet, unsigned int flags,
20		 unsigned int size, const unsigned char *payload)
21{
22#ifdef DEBUG
23	u64 pl = 0;
24
25	if (payload)
26		pl = *(u64 *)payload;
27
28	if (size < 8)
29		pl &= (1ull << (size * 8)) - 1;
30	trace_printk("[%u:%u] [pkt: %x/%x] (%llx)\n", master, channel,
31		     packet, size, pl);
32#endif
33	return size;
34}
35
36#define DUMMY_STM_MAX 32
37
38static struct stm_data dummy_stm[DUMMY_STM_MAX];
39
40static int nr_dummies = 4;
41
42module_param(nr_dummies, int, 0400);
43
44static unsigned int fail_mode;
45
46module_param(fail_mode, int, 0600);
47
48static unsigned int master_min;
49
50module_param(master_min, int, 0400);
51
52static unsigned int master_max = STP_MASTER_MAX;
53
54module_param(master_max, int, 0400);
55
56static unsigned int nr_channels = STP_CHANNEL_MAX;
57
58module_param(nr_channels, int, 0400);
59
60static int dummy_stm_link(struct stm_data *data, unsigned int master,
61			  unsigned int channel)
62{
63	if (fail_mode && (channel & fail_mode))
64		return -EINVAL;
65
66	return 0;
67}
68
69static int dummy_stm_init(void)
70{
71	int i, ret = -ENOMEM;
72
73	if (nr_dummies < 0 || nr_dummies > DUMMY_STM_MAX)
74		return -EINVAL;
75
76	if (master_min > master_max ||
77	    master_max > STP_MASTER_MAX ||
78	    nr_channels > STP_CHANNEL_MAX)
79		return -EINVAL;
80
81	for (i = 0; i < nr_dummies; i++) {
82		dummy_stm[i].name = kasprintf(GFP_KERNEL, "dummy_stm.%d", i);
83		if (!dummy_stm[i].name)
84			goto fail_unregister;
85
86		dummy_stm[i].sw_start		= master_min;
87		dummy_stm[i].sw_end		= master_max;
88		dummy_stm[i].sw_nchannels	= nr_channels;
89		dummy_stm[i].packet		= dummy_stm_packet;
90		dummy_stm[i].link		= dummy_stm_link;
91
92		ret = stm_register_device(NULL, &dummy_stm[i], THIS_MODULE);
93		if (ret)
94			goto fail_free;
95	}
96
97	return 0;
98
99fail_unregister:
100	for (i--; i >= 0; i--) {
101		stm_unregister_device(&dummy_stm[i]);
102fail_free:
103		kfree(dummy_stm[i].name);
104	}
105
106	return ret;
107
108}
109
110static void dummy_stm_exit(void)
111{
112	int i;
113
114	for (i = 0; i < nr_dummies; i++) {
115		stm_unregister_device(&dummy_stm[i]);
116		kfree(dummy_stm[i].name);
117	}
118}
119
120module_init(dummy_stm_init);
121module_exit(dummy_stm_exit);
122
123MODULE_LICENSE("GPL v2");
124MODULE_DESCRIPTION("dummy_stm device");
125MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
126