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
17 static ssize_t notrace
dummy_stm_packet(struct stm_data * stm_data,unsigned int master,unsigned int channel,unsigned int packet,unsigned int flags,unsigned int size,const unsigned char * payload)18 dummy_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
38 static struct stm_data dummy_stm[DUMMY_STM_MAX];
39
40 static int nr_dummies = 4;
41
42 module_param(nr_dummies, int, 0400);
43
44 static unsigned int fail_mode;
45
46 module_param(fail_mode, int, 0600);
47
48 static unsigned int master_min;
49
50 module_param(master_min, int, 0400);
51
52 static unsigned int master_max = STP_MASTER_MAX;
53
54 module_param(master_max, int, 0400);
55
56 static unsigned int nr_channels = STP_CHANNEL_MAX;
57
58 module_param(nr_channels, int, 0400);
59
dummy_stm_link(struct stm_data * data,unsigned int master,unsigned int channel)60 static 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
dummy_stm_init(void)69 static 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
99 fail_unregister:
100 for (i--; i >= 0; i--) {
101 stm_unregister_device(&dummy_stm[i]);
102 fail_free:
103 kfree(dummy_stm[i].name);
104 }
105
106 return ret;
107
108 }
109
dummy_stm_exit(void)110 static 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
120 module_init(dummy_stm_init);
121 module_exit(dummy_stm_exit);
122
123 MODULE_LICENSE("GPL v2");
124 MODULE_DESCRIPTION("dummy_stm device");
125 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
126