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linux-next/arch/powerpc/sysdev/dart.h
Linas Vepstas 5d2efba64b [POWERPC] Use 4kB iommu pages even on 64kB-page systems
The 10Gigabit ethernet device drivers appear to be able to chew
up all 256MB of TCE mappings on pSeries systems, as evidenced by
numerous error messages:

 iommu_alloc failed, tbl c0000000010d5c48 vaddr c0000000d875eff0 npages 1

Some experimentation indicates that this is essentially because
one 1500 byte ethernet MTU gets mapped as a 64K DMA region when
the large 64K pages are enabled. Thus, it doesn't take much to
exhaust all of the available DMA mappings for a high-speed card.

This patch changes the iommu allocator to work with its own
unique, distinct page size. Although the patch is long, its
actually quite simple: it just #defines a distinct IOMMU_PAGE_SIZE
and then uses this in all the places that matter.

As a side effect, it also dramatically improves network performance
on platforms with H-calls on iommu translation inserts/removes (since
we no longer call it 16 times for a 1500 bytes packet when the iommu HW
is still 4k).

In the future, we might want to make the IOMMU_PAGE_SIZE a variable
in the iommu_table instance, thus allowing support for different HW
page sizes in the iommu itself.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-11-01 14:52:48 +11:00

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2.2 KiB
C

/*
* Copyright (C) 2004 Olof Johansson <olof@lixom.net>, IBM Corporation
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _POWERPC_SYSDEV_DART_H
#define _POWERPC_SYSDEV_DART_H
/* Offset from base to control register */
#define DART_CNTL 0
/* Offset from base to exception register */
#define DART_EXCP_U3 0x10
/* Offset from base to TLB tag registers */
#define DART_TAGS_U3 0x1000
/* U4 registers */
#define DART_BASE_U4 0x10
#define DART_SIZE_U4 0x20
#define DART_EXCP_U4 0x30
#define DART_TAGS_U4 0x1000
/* Control Register fields */
/* U3 registers */
#define DART_CNTL_U3_BASE_MASK 0xfffff
#define DART_CNTL_U3_BASE_SHIFT 12
#define DART_CNTL_U3_FLUSHTLB 0x400
#define DART_CNTL_U3_ENABLE 0x200
#define DART_CNTL_U3_SIZE_MASK 0x1ff
#define DART_CNTL_U3_SIZE_SHIFT 0
/* U4 registers */
#define DART_BASE_U4_BASE_MASK 0xffffff
#define DART_BASE_U4_BASE_SHIFT 0
#define DART_CNTL_U4_ENABLE 0x80000000
#define DART_CNTL_U4_IONE 0x40000000
#define DART_CNTL_U4_FLUSHTLB 0x20000000
#define DART_CNTL_U4_IDLE 0x10000000
#define DART_CNTL_U4_PAR_EN 0x08000000
#define DART_CNTL_U4_IONE_MASK 0x07ffffff
#define DART_SIZE_U4_SIZE_MASK 0x1fff
#define DART_SIZE_U4_SIZE_SHIFT 0
#define DART_REG(r) (dart + ((r) >> 2))
#define DART_IN(r) (in_be32(DART_REG(r)))
#define DART_OUT(r,v) (out_be32(DART_REG(r), (v)))
/* size of table in pages */
/* DART table fields */
#define DARTMAP_VALID 0x80000000
#define DARTMAP_RPNMASK 0x00ffffff
#define DART_PAGE_SHIFT 12
#define DART_PAGE_SIZE (1 << DART_PAGE_SHIFT)
#endif /* _POWERPC_SYSDEV_DART_H */