1 /*
2  * A dummy STM device for stm/stm_source class testing.
3  * Copyright (c) 2014, Intel Corporation.
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  * STM class implements generic infrastructure for  System Trace Module devices
15  * as defined in MIPI STPv2 specification.
16  */
17 
18 #undef DEBUG
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/stm.h>
23 
24 static ssize_t notrace
25 dummy_stm_packet(struct stm_data *stm_data, unsigned int master,
26 		 unsigned int channel, unsigned int packet, unsigned int flags,
27 		 unsigned int size, const unsigned char *payload)
28 {
29 #ifdef DEBUG
30 	u64 pl = 0;
31 
32 	if (payload)
33 		pl = *(u64 *)payload;
34 
35 	if (size < 8)
36 		pl &= (1ull << (size * 8)) - 1;
37 	trace_printk("[%u:%u] [pkt: %x/%x] (%llx)\n", master, channel,
38 		     packet, size, pl);
39 #endif
40 	return size;
41 }
42 
43 #define DUMMY_STM_MAX 32
44 
45 static struct stm_data dummy_stm[DUMMY_STM_MAX];
46 
47 static int nr_dummies = 4;
48 
49 module_param(nr_dummies, int, 0400);
50 
51 static unsigned int fail_mode;
52 
53 module_param(fail_mode, int, 0600);
54 
55 static int dummy_stm_link(struct stm_data *data, unsigned int master,
56 			  unsigned int channel)
57 {
58 	if (fail_mode && (channel & fail_mode))
59 		return -EINVAL;
60 
61 	return 0;
62 }
63 
64 static int dummy_stm_init(void)
65 {
66 	int i, ret = -ENOMEM;
67 
68 	if (nr_dummies < 0 || nr_dummies > DUMMY_STM_MAX)
69 		return -EINVAL;
70 
71 	for (i = 0; i < nr_dummies; i++) {
72 		dummy_stm[i].name = kasprintf(GFP_KERNEL, "dummy_stm.%d", i);
73 		if (!dummy_stm[i].name)
74 			goto fail_unregister;
75 
76 		dummy_stm[i].sw_start		= 0x0000;
77 		dummy_stm[i].sw_end		= 0xffff;
78 		dummy_stm[i].sw_nchannels	= 0xffff;
79 		dummy_stm[i].packet		= dummy_stm_packet;
80 		dummy_stm[i].link		= dummy_stm_link;
81 
82 		ret = stm_register_device(NULL, &dummy_stm[i], THIS_MODULE);
83 		if (ret)
84 			goto fail_free;
85 	}
86 
87 	return 0;
88 
89 fail_unregister:
90 	for (i--; i >= 0; i--) {
91 		stm_unregister_device(&dummy_stm[i]);
92 fail_free:
93 		kfree(dummy_stm[i].name);
94 	}
95 
96 	return ret;
97 
98 }
99 
100 static void dummy_stm_exit(void)
101 {
102 	int i;
103 
104 	for (i = 0; i < nr_dummies; i++) {
105 		stm_unregister_device(&dummy_stm[i]);
106 		kfree(dummy_stm[i].name);
107 	}
108 }
109 
110 module_init(dummy_stm_init);
111 module_exit(dummy_stm_exit);
112 
113 MODULE_LICENSE("GPL v2");
114 MODULE_DESCRIPTION("dummy_stm device");
115 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
116