drivers/hwtracing/stm/dummy_stm.c

   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
  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, 0600);
  50
  51 static unsigned int dummy_stm_nr;
  52
  53 static unsigned int fail_mode;
  54
  55 module_param(fail_mode, int, 0600);
  56
  57 static int dummy_stm_link(struct stm_data *data, unsigned int master,
  58                           unsigned int channel)
  59 {
  60         if (fail_mode && (channel & fail_mode))
  61                 return -EINVAL;
  62
  63         return 0;
  64 }
  65
  66 static int dummy_stm_init(void)
  67 {
  68         int i, ret = -ENOMEM, __nr_dummies = ACCESS_ONCE(nr_dummies);
  69
  70         if (__nr_dummies < 0 || __nr_dummies > DUMMY_STM_MAX)
  71                 return -EINVAL;
  72
  73         for (i = 0; i < __nr_dummies; i++) {
  74                 dummy_stm[i].name = kasprintf(GFP_KERNEL, "dummy_stm.%d", i);
  75                 if (!dummy_stm[i].name)
  76                         goto fail_unregister;
  77
  78                 dummy_stm[i].sw_start           = 0x0000;
  79                 dummy_stm[i].sw_end             = 0xffff;
  80                 dummy_stm[i].sw_nchannels       = 0xffff;
  81                 dummy_stm[i].packet             = dummy_stm_packet;
  82                 dummy_stm[i].link               = dummy_stm_link;
  83
  84                 ret = stm_register_device(NULL, &dummy_stm[i], THIS_MODULE);
  85                 if (ret)
  86                         goto fail_free;
  87         }
  88
  89         dummy_stm_nr = __nr_dummies;
  90
  91         return 0;
  92
  93 fail_unregister:
  94         for (i--; i >= 0; i--) {
  95                 stm_unregister_device(&dummy_stm[i]);
  96 fail_free:
  97                 kfree(dummy_stm[i].name);
  98         }
  99
 100         return ret;
 101
 102 }
 103
 104 static void dummy_stm_exit(void)
 105 {
 106         int i;
 107
 108         for (i = 0; i < dummy_stm_nr; i++) {
 109                 stm_unregister_device(&dummy_stm[i]);
 110                 kfree(dummy_stm[i].name);
 111         }
 112 }
 113
 114 module_init(dummy_stm_init);
 115 module_exit(dummy_stm_exit);
 116
 117 MODULE_LICENSE("GPL v2");
 118 MODULE_DESCRIPTION("dummy_stm device");
 119 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");