sysctl.c

Go to the documentation of this file.

/* sysctl.c: implementation of /proc/sys files relating to FRV specifically
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <asm/uaccess.h>

static const char frv_cache_wback[] = "wback";
static const char frv_cache_wthru[] = "wthru";

static void frv_change_dcache_mode(unsigned long newmode)
{
    unsigned long flags, hsr0;

    local_irq_save(flags);

    hsr0 = __get_HSR(0);
    hsr0 &= ~HSR0_DCE;
    __set_HSR(0, hsr0);

    asm volatile("  dcef    @(gr0,gr0),#1   \n"
             "  membar          \n"
             : : : "memory"
             );

    hsr0 = (hsr0 & ~HSR0_CBM) | newmode;
    __set_HSR(0, hsr0);
    hsr0 |= HSR0_DCE;
    __set_HSR(0, hsr0);

    local_irq_restore(flags);

    //printk("HSR0 now %08lx\n", hsr0);
}

/*****************************************************************************/
/*
 * handle requests to dynamically switch the write caching mode delivered by /proc
 */
static int procctl_frv_cachemode(ctl_table *table, int write,
                 void __user *buffer, size_t *lenp,
                 loff_t *ppos)
{
    unsigned long hsr0;
    char buff[8];
    int len;

    len = *lenp;

    if (write) {
        /* potential state change */
        if (len <= 1 || len > sizeof(buff) - 1)
            return -EINVAL;

        if (copy_from_user(buff, buffer, len) != 0)
            return -EFAULT;

        if (buff[len - 1] == '\n')
            buff[len - 1] = '\0';
        else
            buff[len] = '\0';

        if (strcmp(buff, frv_cache_wback) == 0) {
            /* switch dcache into write-back mode */
            frv_change_dcache_mode(HSR0_CBM_COPY_BACK);
            return 0;
        }

        if (strcmp(buff, frv_cache_wthru) == 0) {
            /* switch dcache into write-through mode */
            frv_change_dcache_mode(HSR0_CBM_WRITE_THRU);
            return 0;
        }

        return -EINVAL;
    }

    /* read the state */
    if (*ppos > 0) {
        *lenp = 0;
        return 0;
    }

    hsr0 = __get_HSR(0);
    switch (hsr0 & HSR0_CBM) {
    case HSR0_CBM_WRITE_THRU:
        memcpy(buff, frv_cache_wthru, sizeof(frv_cache_wthru) - 1);
        buff[sizeof(frv_cache_wthru) - 1] = '\n';
        len = sizeof(frv_cache_wthru);
        break;
    default:
        memcpy(buff, frv_cache_wback, sizeof(frv_cache_wback) - 1);
        buff[sizeof(frv_cache_wback) - 1] = '\n';
        len = sizeof(frv_cache_wback);
        break;
    }

    if (len > *lenp)
        len = *lenp;

    if (copy_to_user(buffer, buff, len) != 0)
        return -EFAULT;

    *lenp = len;
    *ppos = len;
    return 0;

} /* end procctl_frv_cachemode() */

/*****************************************************************************/
/*
 * permit the mm_struct the nominated process is using have its MMU context ID pinned
 */
#ifdef CONFIG_MMU
static int procctl_frv_pin_cxnr(ctl_table *table, int write,
                void __user *buffer, size_t *lenp,
                loff_t *ppos)
{
    pid_t pid;
    char buff[16], *p;
    int len;

    len = *lenp;

    if (write) {
        /* potential state change */
        if (len <= 1 || len > sizeof(buff) - 1)
            return -EINVAL;

        if (copy_from_user(buff, buffer, len) != 0)
            return -EFAULT;

        if (buff[len - 1] == '\n')
            buff[len - 1] = '\0';
        else
            buff[len] = '\0';

        pid = simple_strtoul(buff, &p, 10);
        if (*p)
            return -EINVAL;

        return cxn_pin_by_pid(pid);
    }

    /* read the currently pinned CXN */
    if (*ppos > 0) {
        *lenp = 0;
        return 0;
    }

    len = snprintf(buff, sizeof(buff), "%d\n", cxn_pinned);
    if (len > *lenp)
        len = *lenp;

    if (copy_to_user(buffer, buff, len) != 0)
        return -EFAULT;

    *lenp = len;
    *ppos = len;
    return 0;

} /* end procctl_frv_pin_cxnr() */
#endif

/*
 * FR-V specific sysctls
 */
static struct ctl_table frv_table[] =
{
    {
        .procname   = "cache-mode",
        .data       = NULL,
        .maxlen     = 0,
        .mode       = 0644,
        .proc_handler   = procctl_frv_cachemode,
    },
#ifdef CONFIG_MMU
    {
        .procname   = "pin-cxnr",
        .data       = NULL,
        .maxlen     = 0,
        .mode       = 0644,
        .proc_handler   = procctl_frv_pin_cxnr
    },
#endif
    {}
};

/*
 * Use a temporary sysctl number. Horrid, but will be cleaned up in 2.6
 * when all the PM interfaces exist nicely.
 */
static struct ctl_table frv_dir_table[] =
{
    {
        .procname   = "frv",
        .mode       = 0555,
        .child      = frv_table
    },
    {}
};

/*
 * Initialize power interface
 */
static int __init frv_sysctl_init(void)
{
    register_sysctl_table(frv_dir_table);
    return 0;
}

__initcall(frv_sysctl_init);