/* sysctl.c: implementation of /proc/sys files relating to FRV specifically
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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/slab.h>
#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, struct file *filp,
                                 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 (filp->f_pos > 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;
        filp->f_pos = 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, struct file *filp,
                                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 (filp->f_pos > 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;
        filp->f_pos = len;
        return 0;

} /* end procctl_frv_pin_cxnr() */
#endif

/*
 * FR-V specific sysctls
 */
static struct ctl_table frv_table[] =
{
        {
                .ctl_name       = 1,
                .procname       = "cache-mode",
                .data           = NULL,
                .maxlen         = 0,
                .mode           = 0644,
                .proc_handler   = &procctl_frv_cachemode,
        },
#ifdef CONFIG_MMU
        {
                .ctl_name       = 2,
                .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[] =
{
        {
                .ctl_name       = CTL_FRV,
                .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);