[PATCH] m68k: fix dma allocation for ColdFire with mmu

[Angelo Dureghello]

From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>

This patch fixes the following issue on mcf54415:

[    2.270000] fsl-dspi fsl-dspi.0: Not able to get desc for DMA xfer
[    2.280000] fsl-dspi fsl-dspi.0: DMA transfer failed
[    2.280000] spi_master spi0: failed to transfer one message from queue
[    2.290000] spi_master spi0: noqueue transfer failed
[    2.290000] spi-nor spi0.1: probe with driver spi-nor failed with error -5

related to mcf-edma and spi-fsl-dspi drivers (dspi is using edma), visible
after the commit listed below.

The mmu available on some evoluted ColdFire SoCs as mcf54415 allows to
have a coherent dma allocation, so modify code accordingly.

Fixes: 7a360df941a4 ("m68k: don't provide arch_dma_alloc for nommu/coldfire")
Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
---
 arch/m68k/Kconfig      | 4 ++--
 arch/m68k/kernel/dma.c | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 11835eb59d94..edbf6bc9c55a 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -7,7 +7,7 @@ config M68K
 	select ARCH_HAS_CPU_CACHE_ALIASING
 	select ARCH_HAS_CPU_FINALIZE_INIT if MMU
 	select ARCH_HAS_CURRENT_STACK_POINTER
-	select ARCH_HAS_DMA_PREP_COHERENT if M68K_NONCOHERENT_DMA && !COLDFIRE
+	select ARCH_HAS_DMA_PREP_COHERENT if M68K_NONCOHERENT_DMA && (!COLDFIRE || MMU)
 	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
@@ -15,7 +15,7 @@ config M68K
 	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 M68K_NONCOHERENT_DMA && !COLDFIRE
+	select DMA_DIRECT_REMAP if M68K_NONCOHERENT_DMA && (!COLDFIRE || MMU)
 	select GENERIC_ATOMIC64
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IOMAP if HAS_IOPORT && MMU && !COLDFIRE
diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c
index 16063783aa80..59233ebe3a63 100644
--- a/arch/m68k/kernel/dma.c
+++ b/arch/m68k/kernel/dma.c
@@ -8,12 +8,14 @@
 #include <linux/kernel.h>
 #include <asm/cacheflush.h>
 
-#ifndef CONFIG_COLDFIRE
+#ifdef CONFIG_MMU
 void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	cache_push(page_to_phys(page), size);
 }
+#endif
 
+#ifndef CONFIG_COLDFIRE
 pgprot_t pgprot_dmacoherent(pgprot_t prot)
 {
 	if (CPU_IS_040_OR_060) {
@@ -24,7 +26,7 @@ pgprot_t pgprot_dmacoherent(pgprot_t prot)
 	}
 	return prot;
 }
-#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
+#endif /* !CONFIG_COLDFIRE */
 
 void arch_sync_dma_for_device(phys_addr_t handle, size_t size,
 		enum dma_data_direction dir)

---
base-commit: cf72ff0dc9ecc711965604b4241314454d1f9ff3
change-id: 20260525-wip-bl-mcf-edma-7b402ae2f3f8

Best regards,
--  
Angelo Dureghello <adureghello@xxxxxxxxxxxx>