// SPDX-License-Identifier: GPL-2.0
/*
 * A dummy STM device for stm/stm_source class testing.
 * Copyright (c) 2014, Intel Corporation.
 *
 * STM class implements generic infrastructure for  System Trace Module devices
 * as defined in MIPI STPv2 specification.
 */

#undef DEBUG
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/stm.h>
#include <uapi/linux/stm.h>

static ssize_t notrace
dummy_stm_packet(struct stm_data *stm_data, unsigned int master,
                 unsigned int channel, unsigned int packet, unsigned int flags,
                 unsigned int size, const unsigned char *payload)
{
#ifdef DEBUG
        u64 pl = 0;

        if (payload)
                pl = *(u64 *)payload;

        if (size < 8)
                pl &= (1ull << (size * 8)) - 1;
        trace_printk("[%u:%u] [pkt: %x/%x] (%llx)\n", master, channel,
                     packet, size, pl);
#endif
        return size;
}

#define DUMMY_STM_MAX 32

static struct stm_data dummy_stm[DUMMY_STM_MAX];

static int nr_dummies = 4;

module_param(nr_dummies, int, 0400);

static unsigned int fail_mode;

module_param(fail_mode, int, 0600);

static unsigned int master_min;

module_param(master_min, int, 0400);

static unsigned int master_max = STP_MASTER_MAX;

module_param(master_max, int, 0400);

static unsigned int nr_channels = STP_CHANNEL_MAX;

module_param(nr_channels, int, 0400);

static int dummy_stm_link(struct stm_data *data, unsigned int master,
                          unsigned int channel)
{
        if (fail_mode && (channel & fail_mode))
                return -EINVAL;

        return 0;
}

static int dummy_stm_init(void)
{
        int i, ret = -ENOMEM;

        if (nr_dummies < 0 || nr_dummies > DUMMY_STM_MAX)
                return -EINVAL;

        if (master_min > master_max ||
            master_max > STP_MASTER_MAX ||
            nr_channels > STP_CHANNEL_MAX)
                return -EINVAL;

        for (i = 0; i < nr_dummies; i++) {
                dummy_stm[i].name = kasprintf(GFP_KERNEL, "dummy_stm.%d", i);
                if (!dummy_stm[i].name)
                        goto fail_unregister;

                dummy_stm[i].sw_start           = master_min;
                dummy_stm[i].sw_end             = master_max;
                dummy_stm[i].sw_nchannels       = nr_channels;
                dummy_stm[i].packet             = dummy_stm_packet;
                dummy_stm[i].link               = dummy_stm_link;

                ret = stm_register_device(NULL, &dummy_stm[i], THIS_MODULE);
                if (ret)
                        goto fail_free;
        }

        return 0;

fail_unregister:
        for (i--; i >= 0; i--) {
                stm_unregister_device(&dummy_stm[i]);
fail_free:
                kfree(dummy_stm[i].name);
        }

        return ret;

}

static void dummy_stm_exit(void)
{
        int i;

        for (i = 0; i < nr_dummies; i++) {
                stm_unregister_device(&dummy_stm[i]);
                kfree(dummy_stm[i].name);
        }
}

module_init(dummy_stm_init);
module_exit(dummy_stm_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("dummy_stm device");
MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");