root/arch/x86/mm/testmmiotrace.c

DEFINITIONS

1. do_write_test
2. do_read_test
3. do_test
4. cleanup

/*
 * Written by Pekka Paalanen, 2008 <pq@iki.fi>
 */
#include <linux/module.h>
#include <linux/io.h>

#define MODULE_NAME "testmmiotrace"

static unsigned long mmio_address;
module_param(mmio_address, ulong, 0);
MODULE_PARM_DESC(mmio_address, "Start address of the mapping of 16 kB.");

static void do_write_test(void __iomem *p)
{
        unsigned int i;
        for (i = 0; i < 256; i++)
                iowrite8(i, p + i);
        for (i = 1024; i < (5 * 1024); i += 2)
                iowrite16(i * 12 + 7, p + i);
        for (i = (5 * 1024); i < (16 * 1024); i += 4)
                iowrite32(i * 212371 + 13, p + i);
}

static void do_read_test(void __iomem *p)
{
        unsigned int i;
        for (i = 0; i < 256; i++)
                ioread8(p + i);
        for (i = 1024; i < (5 * 1024); i += 2)
                ioread16(p + i);
        for (i = (5 * 1024); i < (16 * 1024); i += 4)
                ioread32(p + i);
}

static void do_test(void)
{
        void __iomem *p = ioremap_nocache(mmio_address, 0x4000);
        if (!p) {
                pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
                return;
        }
        do_write_test(p);
        do_read_test(p);
        iounmap(p);
}

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

        pr_warning(MODULE_NAME ": WARNING: mapping 16 kB @ 0x%08lx "
                                        "in PCI address space, and writing "
                                        "rubbish in there.\n", mmio_address);
        do_test();
        return 0;
}

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

module_init(init);
module_exit(cleanup);
MODULE_LICENSE("GPL");