// SPDX-License-Identifier: GPL-2.0-only
/*
 * Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/io.h>
#include <linux/mmiotrace.h>
#include <linux/security.h>

static unsigned long mmio_address;
module_param_hw(mmio_address, ulong, iomem, 0);
MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
                                "(or 8 MB if read_far is non-zero).");

static unsigned long read_far = 0x400100;
module_param(read_far, ulong, 0);
MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
                                "(default: 0x400100).");

static unsigned v16(unsigned i)
{
        return i * 12 + 7;
}

static unsigned v32(unsigned i)
{
        return i * 212371 + 13;
}

static void do_write_test(void __iomem *p)
{
        unsigned int i;
        pr_info("write test.\n");
        mmiotrace_printk("Write test.\n");

        for (i = 0; i < 256; i++)
                iowrite8(i, p + i);

        for (i = 1024; i < (5 * 1024); i += 2)
                iowrite16(v16(i), p + i);

        for (i = (5 * 1024); i < (16 * 1024); i += 4)
                iowrite32(v32(i), p + i);
}

static void do_read_test(void __iomem *p)
{
        unsigned int i;
        unsigned errs[3] = { 0 };
        pr_info("read test.\n");
        mmiotrace_printk("Read test.\n");

        for (i = 0; i < 256; i++)
                if (ioread8(p + i) != i)
                        ++errs[0];

        for (i = 1024; i < (5 * 1024); i += 2)
                if (ioread16(p + i) != v16(i))
                        ++errs[1];

        for (i = (5 * 1024); i < (16 * 1024); i += 4)
                if (ioread32(p + i) != v32(i))
                        ++errs[2];

        mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
                                                errs[0], errs[1], errs[2]);
}

static void do_read_far_test(void __iomem *p)
{
        pr_info("read far test.\n");
        mmiotrace_printk("Read far test.\n");

        ioread32(p + read_far);
}

static void do_test(unsigned long size)
{
        void __iomem *p = ioremap(mmio_address, size);
        if (!p) {
                pr_err("could not ioremap, aborting.\n");
                return;
        }
        mmiotrace_printk("ioremap returned %p.\n", p);
        do_write_test(p);
        do_read_test(p);
        if (read_far && read_far < size - 4)
                do_read_far_test(p);
        iounmap(p);
}

/*
 * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
 * a short time. We had a bug in deferred freeing procedure which tried
 * to free this region multiple times (ioremap can reuse the same address
 * for many mappings).
 */
static void do_test_bulk_ioremapping(void)
{
        void __iomem *p;
        int i;

        for (i = 0; i < 10; ++i) {
                p = ioremap(mmio_address, PAGE_SIZE);
                if (p)
                        iounmap(p);
        }

        /* Force freeing. If it will crash we will know why. */
        synchronize_rcu();
}

static int __init init(void)
{
        unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
        int ret = security_locked_down(LOCKDOWN_MMIOTRACE);

        if (ret)
                return ret;

        if (mmio_address == 0) {
                pr_err("you have to use the module argument mmio_address.\n");
                pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
                return -ENXIO;
        }

        pr_warn("WARNING: mapping %lu kB @ 0x%08lx in PCI address space, "
                "and writing 16 kB of rubbish in there.\n",
                size >> 10, mmio_address);
        do_test(size);
        do_test_bulk_ioremapping();
        pr_info("All done.\n");
        return 0;
}

static void __exit cleanup(void)
{
        pr_debug("unloaded.\n");
}

module_init(init);
module_exit(cleanup);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Test module for mmiotrace");