Some architectures, notably arm64, are interested in tweaking this
depending on their runtime dma addressing limitations.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
arch/powerpc/include/asm/page.h | 9 ---------
arch/powerpc/mm/mem.c | 14 ++++++++++++--
arch/s390/include/asm/page.h | 2 --
arch/s390/mm/init.c | 1 +
include/linux/dma-direct.h | 2 ++
kernel/dma/direct.c | 8 +++-----
6 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 0d52f57fca04..73668a21ae78 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -319,13 +319,4 @@ struct vm_area_struct;
#endif /* __ASSEMBLY__ */
#include <asm/slice.h>
-/*
- * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.
- */
-#ifdef CONFIG_PPC32
-#define ARCH_ZONE_DMA_BITS 30
-#else
-#define ARCH_ZONE_DMA_BITS 31
-#endif
-
#endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9191a66b3bc5..3792a998ca02 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -31,6 +31,7 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/memremap.h>
+#include <linux/dma-direct.h>
#include <asm/pgalloc.h>
#include <asm/prom.h>
@@ -201,7 +202,7 @@ static int __init mark_nonram_nosave(void)
* everything else. GFP_DMA32 page allocations automatically fall back to
* ZONE_DMA.
*
- * By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to
+ * By using 31-bit unconditionally, we can exploit arch_zone_dma_bits to
* inform the generic DMA mapping code. 32-bit only devices (if not handled
* by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get
* otherwise served by ZONE_DMA.
@@ -237,9 +238,18 @@ void __init paging_init(void)
printk(KERN_DEBUG "Memory hole size: %ldMB\n",
(long int)((top_of_ram - total_ram) >> 20));
+ /*
+ * Allow 30-bit DMA for very limited Broadcom wifi chips on many
+ * powerbooks.
+ */
+ if (IS_ENABLED(CONFIG_PPC32))
+ arch_zone_dma_bits = 30;
+ else
+ arch_zone_dma_bits = 31;
+
#ifdef CONFIG_ZONE_DMA
max_zone_pfns[ZONE_DMA] = min(max_low_pfn,
- 1UL << (ARCH_ZONE_DMA_BITS - PAGE_SHIFT));
+ 1UL << (arch_zone_dma_bits - PAGE_SHIFT));
#endif
max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
#ifdef CONFIG_HIGHMEM
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 823578c6b9e2..a4d38092530a 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -177,8 +177,6 @@ static inline int devmem_is_allowed(unsigned long pfn)
#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-#define ARCH_ZONE_DMA_BITS 31
-
#include <asm-generic/memory_model.h>
#include <asm-generic/getorder.h>
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 20340a03ad90..07d93955d3e4 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -118,6 +118,7 @@ void __init paging_init(void)
sparse_memory_present_with_active_regions(MAX_NUMNODES);
sparse_init();
+ arch_zone_dma_bits = 31;
memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS);
max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index adf993a3bd58..a1b353b77858 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -5,6 +5,8 @@
#include <linux/dma-mapping.h>
#include <linux/mem_encrypt.h>
+extern unsigned int arch_zone_dma_bits;
+
#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
#include <asm/dma-direct.h>
#else
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 59bdceea3737..40dfc9b4ee4c 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -19,9 +19,7 @@
* Most architectures use ZONE_DMA for the first 16 Megabytes, but
* some use it for entirely different regions:
*/
-#ifndef ARCH_ZONE_DMA_BITS
-#define ARCH_ZONE_DMA_BITS 24
-#endif
+unsigned int arch_zone_dma_bits __ro_after_init = 24;
static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
{
@@ -72,7 +70,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
* Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
* zones.
*/
- if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+ if (*phys_mask <= DMA_BIT_MASK(arch_zone_dma_bits))
return GFP_DMA;
if (*phys_mask <= DMA_BIT_MASK(32))
return GFP_DMA32;
@@ -387,7 +385,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
u64 min_mask;
if (IS_ENABLED(CONFIG_ZONE_DMA))
- min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS);
+ min_mask = DMA_BIT_MASK(arch_zone_dma_bits);
else
min_mask = DMA_BIT_MASK(32);
--
2.22.0
