Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5c91fb902d4e6f6006faf45edd3f25932cb7d58c
Commit: 5c91fb902d4e6f6006faf45edd3f25932cb7d58c
Parent: 1754a5d9f97f16f729066b8f125351af4951d6fe
Author: Michael Hennerich <[EMAIL PROTECTED]>
AuthorDate: Sat Nov 17 23:46:58 2007 +0800
Committer: Bryan Wu <[EMAIL PROTECTED]>
CommitDate: Sat Nov 17 23:46:58 2007 +0800
Blackfin arch: Add assembly function insl_16
/*
* CPUs often take a performance hit when accessing unaligned memory
* locations. The actual performance hit varies, it can be small if the
* hardware handles it or large if we have to take an exception and fix
* it
* in software.
*
* Since an ethernet header is 14 bytes network drivers often end up
* with
* the IP header at an unaligned offset. The IP header can be aligned by
* shifting the start of the packet by 2 bytes. Drivers should do this
* with:
*
* skb_reserve(NET_IP_ALIGN);
*
* The downside to this alignment of the IP header is that the DMA is
* now
* unaligned. On some architectures the cost of an unaligned DMA is high
* and this cost outweighs the gains made by aligning the IP header.
*
* Since this trade off varies between architectures, we allow
* NET_IP_ALIGN
* to be overridden.
*/
This new function insl_16 allows to read form 32-bit IO and writes to
16-bit aligned memory. This is useful in above described scenario -
In particular with the AXIS AX88180 Gigabit Ethernet MAC.
Once the device is in 32-bit mode, reads from the RX FIFO always
decrements 4bytes.
While on the other side the destination address in SDRAM is always
16-bit aligned.
If we use skb_reserve(0) the receive buffer is 32-bit aligned but later
we hit a unaligned exception in the IP code.
Signed-off-by: Michael Hennerich <[EMAIL PROTECTED]>
Signed-off-by: Bryan Wu <[EMAIL PROTECTED]>
---
arch/blackfin/kernel/bfin_ksyms.c | 1 +
arch/blackfin/lib/ins.S | 19 +++++++++++++++++++
include/asm-blackfin/io.h | 1 +
3 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/arch/blackfin/kernel/bfin_ksyms.c
b/arch/blackfin/kernel/bfin_ksyms.c
index 5dad9d3..b3fa7d8 100644
--- a/arch/blackfin/kernel/bfin_ksyms.c
+++ b/arch/blackfin/kernel/bfin_ksyms.c
@@ -100,6 +100,7 @@ EXPORT_SYMBOL(outsw);
EXPORT_SYMBOL(insw);
EXPORT_SYMBOL(outsl);
EXPORT_SYMBOL(insl);
+EXPORT_SYMBOL(insl_16);
EXPORT_SYMBOL(irq_flags);
EXPORT_SYMBOL(iounmap);
EXPORT_SYMBOL(blackfin_dcache_invalidate_range);
diff --git a/arch/blackfin/lib/ins.S b/arch/blackfin/lib/ins.S
index a17cc77..df7b883 100644
--- a/arch/blackfin/lib/ins.S
+++ b/arch/blackfin/lib/ins.S
@@ -77,3 +77,22 @@ ENTRY(_insb)
sti R3;
RTS;
ENDPROC(_insb)
+
+
+
+ENTRY(_insl_16)
+ P0 = R0; /* P0 = port */
+ cli R3;
+ P1 = R1; /* P1 = address */
+ P2 = R2; /* P2 = count */
+ SSYNC;
+ LSETUP( .Llong16_loop_s, .Llong16_loop_e) LC0 = P2;
+.Llong16_loop_s: R0 = [P0];
+ W[P1++] = R0;
+ R0 = R0 >> 16;
+ W[P1++] = R0;
+ NOP;
+.Llong16_loop_e: NOP;
+ sti R3;
+ RTS;
+ENDPROC(_insl_16)
diff --git a/include/asm-blackfin/io.h b/include/asm-blackfin/io.h
index d1d2e6b..1601d62 100644
--- a/include/asm-blackfin/io.h
+++ b/include/asm-blackfin/io.h
@@ -122,6 +122,7 @@ extern void outsl(unsigned long port, const void *addr,
unsigned long count);
extern void insb(unsigned long port, void *addr, unsigned long count);
extern void insw(unsigned long port, void *addr, unsigned long count);
extern void insl(unsigned long port, void *addr, unsigned long count);
+extern void insl_16(unsigned long port, void *addr, unsigned long count);
extern void dma_outsb(unsigned long port, const void *addr, unsigned short
count);
extern void dma_outsw(unsigned long port, const void *addr, unsigned short
count);
-
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