drivers/hwtracing/stm/dummy_stm.c

   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>");