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
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 
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 
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 
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