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sysctl.c

/* 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);

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