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m68k: use the coherent DMA code for coldfire without data cache

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Coldfire cores configured without a data cache are DMA coherent and
should thus simply use the simple coherent version of dma-direct.

Introduce a new COLDFIRE_COHERENT_DMA Kconfig symbol as a convenient
short hand for such configurations, and a M68K_NONCOHERENT_DMA symbol
for all cases where we need to build non-coherent DMA infrastructure
to simplify the Kconfig and code conditionals.

Not building the non-coherent DMA code slightly reduces the code
size for such configurations.

Numers for m5249evb_defconfig below:

  text	   data	    bss	    dec	    hex	filename
2896158	 401052	  65392	3362602	 334f2a	vmlinux.before
2895166	 400988	  65392	3361546	 334b0a	vmlinux.after

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Greg Ungerer <gerg@linux-m68k.org>
This commit is contained in:
Christoph Hellwig 2023-10-17 16:04:42 +02:00
parent 63f067e33c
commit 9e28bf8bdf
4 changed files with 18 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/m68k/Kconfig
View File

@ -6,16 +6,16 @@ config M68K
select ARCH_HAS_BINFMT_FLAT
select ARCH_HAS_CPU_FINALIZE_INIT if MMU
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DMA_ALLOC if !MMU || COLDFIRE
select ARCH_HAS_DMA_PREP_COHERENT if HAS_DMA && MMU && !COLDFIRE
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
select ARCH_HAS_DMA_ALLOC if M68K_NONCOHERENT_DMA && COLDFIRE
select ARCH_HAS_DMA_PREP_COHERENT if M68K_NONCOHERENT_DMA && !COLDFIRE
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if M68K_NONCOHERENT_DMA
select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
select ARCH_NO_PREEMPT if !COLDFIRE
select ARCH_USE_MEMTEST if MMU_MOTOROLA
select ARCH_WANT_IPC_PARSE_VERSION
select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE
select DMA_DIRECT_REMAP if M68K_NONCOHERENT_DMA && !COLDFIRE
select GENERIC_ATOMIC64
select GENERIC_CPU_DEVICES
select GENERIC_IOMAP

12
arch/m68k/Kconfig.cpu
View File

@ -535,3 +535,15 @@ config CACHE_COPYBACK
The ColdFire CPU cache is set into Copy-back mode.
endchoice
endif # HAVE_CACHE_CB
# Coldfire cores that do not have a data cache configured can do coherent DMA.
config COLDFIRE_COHERENT_DMA
bool
default y
depends on COLDFIRE
depends on !HAVE_CACHE_CB && !CACHE_D && !CACHE_BOTH
config M68K_NONCOHERENT_DMA
bool
default y
depends on HAS_DMA && !COLDFIRE_COHERENT_DMA

2
arch/m68k/kernel/Makefile
View File

@ -23,7 +23,7 @@ obj-$(CONFIG_MMU_MOTOROLA) += ints.o vectors.o
obj-$(CONFIG_MMU_SUN3) += ints.o vectors.o
obj-$(CONFIG_PCI) += pcibios.o
obj-$(CONFIG_HAS_DMA) += dma.o
obj-$(CONFIG_M68K_NONCOHERENT_DMA) += dma.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_BOOTINFO_PROC) += bootinfo_proc.o

2
arch/m68k/kernel/dma.c
View File

@ -17,7 +17,7 @@
#include <asm/cacheflush.h>
#if defined(CONFIG_MMU) && !defined(CONFIG_COLDFIRE)
#ifndef CONFIG_COLDFIRE
void arch_dma_prep_coherent(struct page *page, size_t size)
{
cache_push(page_to_phys(page), size);