Commit 1a8e1cef authored by Nicolas Saenz Julienne's avatar Nicolas Saenz Julienne Committed by Catalin Marinas
Browse files

arm64: use both ZONE_DMA and ZONE_DMA32 



So far all arm64 devices have supported 32 bit DMA masks for their
peripherals. This is not true anymore for the Raspberry Pi 4 as most of
it's peripherals can only address the first GB of memory on a total of
up to 4 GB.

This goes against ZONE_DMA32's intent, as it's expected for ZONE_DMA32
to be addressable with a 32 bit mask. So it was decided to re-introduce
ZONE_DMA in arm64.

ZONE_DMA will contain the lower 1G of memory, which is currently the
memory area addressable by any peripheral on an arm64 device.
ZONE_DMA32 will contain the rest of the 32 bit addressable memory.

Signed-off-by: default avatarNicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent a573cdd7

arch/arm64/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -266,6 +266,10 @@ config GENERIC_CSUM 
config GENERIC_CALIBRATE_DELAY

	def_bool y



config ZONE_DMA

	bool "Support DMA zone" if EXPERT

	default y



config ZONE_DMA32

	bool "Support DMA32 zone" if EXPERT

	default y

arch/arm64/include/asm/page.h

+2 −0
Original line number Diff line number Diff line
@@ -38,4 +38,6 @@ extern int pfn_valid(unsigned long); 


#include <asm-generic/getorder.h>



#define ARCH_ZONE_DMA_BITS 30



#endif

arch/arm64/mm/init.c

+39 −15
Original line number Diff line number Diff line
@@ -56,6 +56,13 @@ EXPORT_SYMBOL(physvirt_offset); 
struct page *vmemmap __ro_after_init;

EXPORT_SYMBOL(vmemmap);



/*

 * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of

 * memory as some devices, namely the Raspberry Pi 4, have peripherals with

 * this limited view of the memory. ZONE_DMA32 will cover the rest of the 32

 * bit addressable memory area.

 */

phys_addr_t arm64_dma_phys_limit __ro_after_init;

phys_addr_t arm64_dma32_phys_limit __ro_after_init;



#ifdef CONFIG_KEXEC_CORE
@@ -169,15 +176,16 @@ static void __init reserve_elfcorehdr(void) 
{

}

#endif /* CONFIG_CRASH_DUMP */



/*

 * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)). It

 * currently assumes that for memory starting above 4G, 32-bit devices will

 * use a DMA offset.

 * Return the maximum physical address for a zone with a given address size

 * limit. It currently assumes that for memory starting above 4G, 32-bit

 * devices will use a DMA offset.

 */

static phys_addr_t __init max_zone_dma32_phys(void)

static phys_addr_t __init max_zone_phys(unsigned int zone_bits)

{

	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);

	return min(offset + (1ULL << 32), memblock_end_of_DRAM());

	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits);

	return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM());

}



#ifdef CONFIG_NUMA
@@ -186,6 +194,9 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) 
{

	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};



#ifdef CONFIG_ZONE_DMA

	max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);

#endif

#ifdef CONFIG_ZONE_DMA32

	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(arm64_dma32_phys_limit);

#endif
@@ -201,13 +212,18 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) 
	struct memblock_region *reg;

	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];

	unsigned long max_dma32 = min;

	unsigned long max_dma = min;



	memset(zone_size, 0, sizeof(zone_size));



	/* 4GB maximum for 32-bit only capable devices */

#ifdef CONFIG_ZONE_DMA

	max_dma = PFN_DOWN(arm64_dma_phys_limit);

	zone_size[ZONE_DMA] = max_dma - min;

	max_dma32 = max_dma;

#endif

#ifdef CONFIG_ZONE_DMA32

	max_dma32 = PFN_DOWN(arm64_dma32_phys_limit);

	zone_size[ZONE_DMA32] = max_dma32 - min;

	zone_size[ZONE_DMA32] = max_dma32 - max_dma;

#endif

	zone_size[ZONE_NORMAL] = max - max_dma32;
@@ -219,11 +235,17 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) 


		if (start >= max)

			continue;



#ifdef CONFIG_ZONE_DMA

		if (start < max_dma) {

			unsigned long dma_end = min_not_zero(end, max_dma);

			zhole_size[ZONE_DMA] -= dma_end - start;

		}

#endif

#ifdef CONFIG_ZONE_DMA32

		if (start < max_dma32) {

			unsigned long dma_end = min(end, max_dma32);

			zhole_size[ZONE_DMA32] -= dma_end - start;

			unsigned long dma32_end = min(end, max_dma32);

			unsigned long dma32_start = max(start, max_dma);

			zhole_size[ZONE_DMA32] -= dma32_end - dma32_start;

		}

#endif

		if (end > max_dma32) {
@@ -418,9 +440,11 @@ void __init arm64_memblock_init(void) 


	early_init_fdt_scan_reserved_mem();



	/* 4GB maximum for 32-bit only capable devices */

	if (IS_ENABLED(CONFIG_ZONE_DMA))

		arm64_dma_phys_limit = max_zone_phys(ARCH_ZONE_DMA_BITS);



	if (IS_ENABLED(CONFIG_ZONE_DMA32))

		arm64_dma32_phys_limit = max_zone_dma32_phys();

		arm64_dma32_phys_limit = max_zone_phys(32);

	else

		arm64_dma32_phys_limit = PHYS_MASK + 1;
@@ -430,7 +454,7 @@ void __init arm64_memblock_init(void) 


	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;



	dma_contiguous_reserve(arm64_dma32_phys_limit);

	dma_contiguous_reserve(arm64_dma_phys_limit ? : arm64_dma32_phys_limit);

}



void __init bootmem_init(void)
@@ -534,7 +558,7 @@ static void __init free_unused_memmap(void) 
void __init mem_init(void)

{

	if (swiotlb_force == SWIOTLB_FORCE ||

	    max_pfn > (arm64_dma32_phys_limit >> PAGE_SHIFT))

	    max_pfn > PFN_DOWN(arm64_dma_phys_limit ? : arm64_dma32_phys_limit))

		swiotlb_init(1);

	else

		swiotlb_force = SWIOTLB_NO_FORCE;

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