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 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>");