r1753 - in trunk/linux-2.6.x

[dslinux_amadeus at dslinux.in-berlin.de]

Author: amadeus
Date: 2007-05-07 22:43:35 +0200 (Mon, 07 May 2007)
New Revision: 1753

Log:
Optimize bank switching for DLDI drivers. Idea by Chism.

Modified: trunk/linux-2.6.x/arch/arm/mach-nds/head.S
===================================================================
--- trunk/linux-2.6.x/arch/arm/mach-nds/head.S	2007-05-06 19:26:04 UTC (rev 1752)
+++ trunk/linux-2.6.x/arch/arm/mach-nds/head.S	2007-05-07 20:43:35 UTC (rev 1753)
@@ -281,7 +281,7 @@
 	@ Disable data cache for GBA ROM, unless we have full 8bit write support.
 	@	      gGViWDMI
 	@ NOTE: this code must be synchronous with include/asm-arm/arch-nds/gbarom-macros.S
-	@ and with gbaram.c
+	@ and with gbaram.c and with dldi_s.S
 #if defined(CONFIG_NDS_ROM8BIT) && !defined(CONFIG_NDS_DLDI) 
 	ldr	r0,=0b10000010
 #else

Modified: trunk/linux-2.6.x/drivers/block/dldi_s.S
===================================================================
--- trunk/linux-2.6.x/drivers/block/dldi_s.S	2007-05-06 19:26:04 UTC (rev 1752)
+++ trunk/linux-2.6.x/drivers/block/dldi_s.S	2007-05-07 20:43:35 UTC (rev 1753)
@@ -88,6 +88,16 @@
 
 	.align
 _call_dldi:
+@ test the data cache control if we have RAM at GBA ROM space
+	mrc	p15, 0, r0, c2, c0, 0
+	tst	r0,#0b10000000		@ (this must be synchronous to head.S)
+	beq	_call_dldi_direct	@ data cache inactiv: no need to do the bankswitching stuff
+@ test the DLDI descriptor if this is a slot-1 device
+	ldr	ip,=_io_dldi		@ Address of DLDI descriptor
+	ldr	r0,[ip,#4]		@ read the features word
+	tst	r0,#FEATURE_SLOT_NDS	@ is it a slot 1 card?
+	bne	_call_dldi_stack	@ yes: no need to do the bankswitching, but need a stack in main memory
+@ this is a slot 2 card with RAM in the GBA slot area. Do all the stack and bankswitching magic.
 	ldr	ip,=_param_dldi		@ ip = IO parameter block
 	str	sp,[ip]			@ store old stack pointer
 	str	lr,[ip,#4]		@ store old link register
@@ -113,6 +123,41 @@
 	ldr	r0,[ip,#24]		@ restore result
 	gba_suffix
 	bx	lr			@ return
+@ this is a slot 1 card with a slot 2 ram extension. As DLDI drivers are not compiled with
+@ -mswp-byte-writes, we need to allocate a stack in main memory. And we need to disable interrupts,
+@ because linux is not able to have interrupts with a manipulated stack.
+_call_dldi_stack:
+	ldr	ip,=_param_dldi		@ ip = IO parameter block
+	str	sp,[ip]			@ store old stack pointer
+	str	lr,[ip,#4]		@ store old link register
+	ldr	r3, =NDS_IME		@ interrupt mask register
+	mov	ip, #0			@ 0 = disable
+	strh	ip, [r3]
+	mcr	p15, 0, ip, c7, c10, 4	@ drain write buffer for IME to take effect.
+	ldr	sp,=_stack_dldi		@ set new stack (in main memory!)
+	ldr	ip,=_param_dldi		@ ip = IO parameter block
+	ldr	r0,[ip,#8]		@ read parameter 1
+	ldr	r1,[ip,#12]		@ read parameter 2
+	ldr	r2,[ip,#16]		@ read parameter 3
+	ldr	r3,[ip,#20]		@ read pointer to function
+	blx	r3			@ execute the function
+	ldr	ip,=_param_dldi		@ ip = IO parameter block
+	ldr	sp,[ip]			@ restore stack
+	ldr	lr,[ip,#4]		@ restore link register
+	mov	ip, #0			@ be safe that all switching commands before are executed
+	mcr	p15, 0, ip, c7, c10, 4	@ drain write buffer
+	ldr	r3, =NDS_IME		@ interrupt mask register
+	mov	ip, #1			@ 1 = enable
+	strh	ip, [r3]
+	bx	lr			@ return
+@ direct call without bankswitching.
+_call_dldi_direct:
+	ldr	ip,=_param_dldi		@ ip = IO parameter block
+	ldr	r0,[ip,#8]		@ read parameter 1
+	ldr	r1,[ip,#12]		@ read parameter 2
+	ldr	r2,[ip,#16]		@ read parameter 3
+	ldr	r3,[ip,#20]		@ read pointer to function
+	bx	r3			@ execute function, return to caller
 
 	.pool
 	.align