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ipath_wc_x86_64.c

/*
 * Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
 * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * This file is conditionally built on x86_64 only.  Otherwise weak symbol
 * versions of the functions exported from here are used.
 */

#include <linux/pci.h>
#include <asm/mtrr.h>
#include <asm/processor.h>

#include "ipath_kernel.h"

/**
 * ipath_enable_wc - enable write combining for MMIO writes to the device
 * @dd: infinipath device
 *
 * This routine is x86_64-specific; it twiddles the CPU's MTRRs to enable
 * write combining.
 */
int ipath_enable_wc(struct ipath_devdata *dd)
{
      int ret = 0;
      u64 pioaddr, piolen;
      unsigned bits;
      const unsigned long addr = pci_resource_start(dd->pcidev, 0);
      const size_t len = pci_resource_len(dd->pcidev, 0);

      /*
       * Set the PIO buffers to be WCCOMB, so we get HT bursts to the
       * chip.  Linux (possibly the hardware) requires it to be on a power
       * of 2 address matching the length (which has to be a power of 2).
       * For rev1, that means the base address, for rev2, it will be just
       * the PIO buffers themselves.
       * For chips with two sets of buffers, the calculations are
       * somewhat more complicated; we need to sum, and the piobufbase
       * register has both offsets, 2K in low 32 bits, 4K in high 32 bits.
       * The buffers are still packed, so a single range covers both.
       */
      if (dd->ipath_piobcnt2k && dd->ipath_piobcnt4k) { /* 2 sizes */
            unsigned long pio2kbase, pio4kbase;
            pio2kbase = dd->ipath_piobufbase & 0xffffffffUL;
            pio4kbase = (dd->ipath_piobufbase >> 32) & 0xffffffffUL;
            if (pio2kbase < pio4kbase) { /* all, for now */
                  pioaddr = addr + pio2kbase;
                  piolen = pio4kbase - pio2kbase +
                        dd->ipath_piobcnt4k * dd->ipath_4kalign;
            } else {
                  pioaddr = addr + pio4kbase;
                  piolen = pio2kbase - pio4kbase +
                        dd->ipath_piobcnt2k * dd->ipath_palign;
            }
      } else {  /* single buffer size (2K, currently) */
            pioaddr = addr + dd->ipath_piobufbase;
            piolen = dd->ipath_piobcnt2k * dd->ipath_palign +
                  dd->ipath_piobcnt4k * dd->ipath_4kalign;
      }

      for (bits = 0; !(piolen & (1ULL << bits)); bits++)
            /* do nothing */ ;

      if (piolen != (1ULL << bits)) {
            piolen >>= bits;
            while (piolen >>= 1)
                  bits++;
            piolen = 1ULL << (bits + 1);
      }
      if (pioaddr & (piolen - 1)) {
            u64 atmp;
            ipath_dbg("pioaddr %llx not on right boundary for size "
                    "%llx, fixing\n",
                    (unsigned long long) pioaddr,
                    (unsigned long long) piolen);
            atmp = pioaddr & ~(piolen - 1);
            if (atmp < addr || (atmp + piolen) > (addr + len)) {
                  ipath_dev_err(dd, "No way to align address/size "
                              "(%llx/%llx), no WC mtrr\n",
                              (unsigned long long) atmp,
                              (unsigned long long) piolen << 1);
                  ret = -ENODEV;
            } else {
                  ipath_dbg("changing WC base from %llx to %llx, "
                          "len from %llx to %llx\n",
                          (unsigned long long) pioaddr,
                          (unsigned long long) atmp,
                          (unsigned long long) piolen,
                          (unsigned long long) piolen << 1);
                  pioaddr = atmp;
                  piolen <<= 1;
            }
      }

      if (!ret) {
            int cookie;
            ipath_cdbg(VERBOSE, "Setting mtrr for chip to WC "
                     "(addr %llx, len=0x%llx)\n",
                     (unsigned long long) pioaddr,
                     (unsigned long long) piolen);
            cookie = mtrr_add(pioaddr, piolen, MTRR_TYPE_WRCOMB, 0);
            if (cookie < 0) {
                  {
                        dev_info(&dd->pcidev->dev,
                               "mtrr_add()  WC for PIO bufs "
                               "failed (%d)\n",
                               cookie);
                        ret = -EINVAL;
                  }
            } else {
                  ipath_cdbg(VERBOSE, "Set mtrr for chip to WC, "
                           "cookie is %d\n", cookie);
                  dd->ipath_wc_cookie = cookie;
                  dd->ipath_wc_base = (unsigned long) pioaddr;
                  dd->ipath_wc_len = (unsigned long) piolen;
            }
      }

      return ret;
}

/**
 * ipath_disable_wc - disable write combining for MMIO writes to the device
 * @dd: infinipath device
 */
void ipath_disable_wc(struct ipath_devdata *dd)
{
      if (dd->ipath_wc_cookie) {
            int r;
            ipath_cdbg(VERBOSE, "undoing WCCOMB on pio buffers\n");
            r = mtrr_del(dd->ipath_wc_cookie, dd->ipath_wc_base,
                       dd->ipath_wc_len);
            if (r < 0)
                  dev_info(&dd->pcidev->dev,
                         "mtrr_del(%lx, %lx, %lx) failed: %d\n",
                         dd->ipath_wc_cookie, dd->ipath_wc_base,
                         dd->ipath_wc_len, r);
            dd->ipath_wc_cookie = 0; /* even on failure */
      }
}

/**
 * ipath_unordered_wc - indicate whether write combining is ordered
 *
 * Because our performance depends on our ability to do write combining mmio
 * writes in the most efficient way, we need to know if we are on an Intel
 * or AMD x86_64 processor.  AMD x86_64 processors flush WC buffers out in
 * the order completed, and so no special flushing is required to get
 * correct ordering.  Intel processors, however, will flush write buffers
 * out in "random" orders, and so explicit ordering is needed at times.
 */
int ipath_unordered_wc(void)
{
      return boot_cpu_data.x86_vendor != X86_VENDOR_AMD;
}

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