[PATCH 1/5] swiotlb: SWIOTLB code cleanup

From: Jon Mason
Date: Tue May 09 2006 - 19:56:11 EST


SWIOTLB Cleanup. Mostly a comment and white space clean-up.
However, some compiler cache optimizations (via the static and
__read_mostly keywords) were added, and
swiotlb_init_with_default_size was renamed swiotlb_init (as that
functional was redundant).

This patch has been tested individually and cumulatively on x86_64 and
cross-compile tested on IA64. Since I have no IA64 hardware, any
testing on that platform would be appreciated.

Thanks,
Jon

Signed-off-by: Jon Mason <jdmason@xxxxxxxxxx>

diff -r de9ab457255b -r 1d9d729a821b lib/swiotlb.c
--- a/lib/swiotlb.c Mon May 8 15:10:36 2006
+++ b/lib/swiotlb.c Mon May 8 15:18:59 2006
@@ -8,9 +8,9 @@
* Copyright (C) 2000, 2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@xxxxxxxxxx>
*
- * 03/05/07 davidm Switch from PCI-DMA to generic device DMA API.
* 00/12/13 davidm Rename to swiotlb.c and add mark_clean() to avoid
* unnecessary i-cache flushing.
+ * 03/05/07 davidm Switch from PCI-DMA to generic device DMA API.
* 04/07/.. ak Better overflow handling. Assorted fixes.
* 05/09/10 linville Add support for syncing ranges, support syncing for
* DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
@@ -24,13 +24,11 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ctype.h>
-
+#include <linux/init.h>
+#include <linux/bootmem.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/scatterlist.h>
-
-#include <linux/init.h>
-#include <linux/bootmem.h>

#define OFFSET(val,align) ((unsigned long) \
( (val) & ( (align) - 1)))
@@ -68,27 +66,26 @@
SYNC_FOR_DEVICE = 1,
};

-int swiotlb_force;
+int __read_mostly swiotlb_force;

/*
* Used to do a quick range check in swiotlb_unmap_single and
* swiotlb_sync_single_*, to see if the memory was in fact allocated by this
* API.
*/
-static char *io_tlb_start, *io_tlb_end;
+static __read_mostly char *io_tlb_start, *io_tlb_end;

/*
* The number of IO TLB blocks (in groups of 64) betweeen io_tlb_start and
* io_tlb_end. This is command line adjustable via setup_io_tlb_npages.
*/
-static unsigned long io_tlb_nslabs;
+static __read_mostly unsigned long io_tlb_nslabs;

/*
* When the IOMMU overflows we return a fallback buffer. This sets the size.
*/
-static unsigned long io_tlb_overflow = 32*1024;
-
-void *io_tlb_overflow_buffer;
+static __read_mostly unsigned long io_tlb_overflow = 32*1024;
+static void *io_tlb_overflow_buffer;

/*
* This is a free list describing the number of free entries available from
@@ -130,19 +127,21 @@
* structures for the software IO TLB used to implement the DMA API.
*/
void
-swiotlb_init_with_default_size (size_t default_size)
+swiotlb_init(void)
{
unsigned long i;

if (!io_tlb_nslabs) {
- io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
+ /* if not defined via boot arg, default to 64MB */
+ io_tlb_nslabs = ((64 * (1 << 20)) >> IO_TLB_SHIFT);
io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
}

/*
* Get IO TLB memory from the low pages
*/
- io_tlb_start = alloc_bootmem_low_pages(io_tlb_nslabs * (1 << IO_TLB_SHIFT));
+ io_tlb_start = alloc_bootmem_low_pages(io_tlb_nslabs *
+ (1 << IO_TLB_SHIFT));
if (!io_tlb_start)
panic("Cannot allocate SWIOTLB buffer");
io_tlb_end = io_tlb_start + io_tlb_nslabs * (1 << IO_TLB_SHIFT);
@@ -162,14 +161,9 @@
* Get the overflow emergency buffer
*/
io_tlb_overflow_buffer = alloc_bootmem_low(io_tlb_overflow);
- printk(KERN_INFO "Placing software IO TLB between 0x%lx - 0x%lx\n",
+ printk(KERN_INFO "Placing %dMB software IO TLB between 0x%lx - 0x%lx\n",
+ (int) (io_tlb_nslabs * (1 << IO_TLB_SHIFT)) >> 20,
virt_to_phys(io_tlb_start), virt_to_phys(io_tlb_end));
-}
-
-void
-swiotlb_init (void)
-{
- swiotlb_init_with_default_size(64 * (1<<20)); /* default to 64MB */
}

/*
@@ -178,7 +172,7 @@
* This should be just like above, but with some error catching.
*/
int
-swiotlb_late_init_with_default_size (size_t default_size)
+swiotlb_late_init_with_default_size(size_t default_size)
{
unsigned long i, req_nslabs = io_tlb_nslabs;
unsigned int order;
@@ -250,11 +244,11 @@

cleanup4:
free_pages((unsigned long)io_tlb_orig_addr, get_order(io_tlb_nslabs *
- sizeof(char *)));
+ sizeof(char *)));
io_tlb_orig_addr = NULL;
cleanup3:
free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
- sizeof(int)));
+ sizeof(int)));
io_tlb_list = NULL;
io_tlb_end = NULL;
cleanup2:
@@ -268,7 +262,7 @@
static inline int
address_needs_mapping(struct device *hwdev, dma_addr_t addr)
{
- dma_addr_t mask = 0xffffffff;
+ dma_addr_t mask = DMA_32BIT_MASK;
/* If the device has a mask, use it, otherwise default to 32 bits */
if (hwdev && hwdev->dma_mask)
mask = *hwdev->dma_mask;
@@ -491,7 +485,7 @@
free_pages((unsigned long) vaddr, get_order(size));
else
/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
- swiotlb_unmap_single (hwdev, dma_handle, size, DMA_TO_DEVICE);
+ swiotlb_unmap_single(hwdev, dma_handle, size, DMA_TO_DEVICE);
}

static void
-
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