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
 17static ssize_t notrace
 18dummy_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
 38static struct stm_data dummy_stm[DUMMY_STM_MAX];
 39
 40static int nr_dummies = 4;
 41
 42module_param(nr_dummies, int, 0400);
 43
 44static unsigned int fail_mode;
 45
 46module_param(fail_mode, int, 0600);
 47
 48static unsigned int master_min;
 49
 50module_param(master_min, int, 0400);
 51
 52static unsigned int master_max = STP_MASTER_MAX;
 53
 54module_param(master_max, int, 0400);
 55
 56static unsigned int nr_channels = STP_CHANNEL_MAX;
 57
 58module_param(nr_channels, int, 0400);
 59
 60static 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
 69static 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
 99fail_unregister:
100	for (i--; i >= 0; i--) {
101		stm_unregister_device(&dummy_stm[i]);
102fail_free:
103		kfree(dummy_stm[i].name);
104	}
105
106	return ret;
107
108}
109
110static 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
120module_init(dummy_stm_init);
121module_exit(dummy_stm_exit);
122
123MODULE_LICENSE("GPL v2");
124MODULE_DESCRIPTION("dummy_stm device");
125MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");