From: "Maciej W. Rozycki" macro@linux-mips.org
[ Upstream commit e4849aff1e169b86c561738daf8ff020e9de1011 ]
The Broadcom SiByte BCM1250, BCM1125, and BCM1125H SOCs have an onchip DRAM controller that supports memory amounts of up to 16GiB, and due to how the address decoder has been wired in the SOC any memory beyond 1GiB is actually mapped starting from 4GiB physical up, that is beyond the 32-bit addressable limit[1]. Consequently if the maximum amount of memory has been installed, then it will span up to 19GiB.
Many of the evaluation boards we support that are based on one of these SOCs have their memory soldered and the amount present fits in the 32-bit address range. The BCM91250A SWARM board however has actual DIMM slots and accepts, depending on the peripherals revision of the SOC, up to 4GiB or 8GiB of memory in commercially available JEDEC modules[2]. I believe this is also the case with the BCM91250C2 LittleSur board. This means that up to either 3GiB or 7GiB of memory requires 64-bit addressing to access.
I believe the BCM91480B BigSur board, which has the BCM1480 SOC instead, accepts at least as much memory, although I have no documentation or actual hardware available to verify that.
Both systems have PCI slots installed for use by any PCI option boards, including ones that only support 32-bit addressing (additionally the 32-bit PCI host bridge of the BCM1250, BCM1125, and BCM1125H SOCs limits addressing to 32-bits), and there is no IOMMU available. Therefore for PCI DMA to work in the presence of memory beyond enable swiotlb for the affected systems.
All the other SOC onchip DMA devices use 40-bit addressing and therefore can address the whole memory, so only enable swiotlb if PCI support and support for DMA beyond 4GiB have been both enabled in the configuration of the kernel.
This shows up as follows:
Broadcom SiByte BCM1250 B2 @ 800 MHz (SB1 rev 2) Board type: SiByte BCM91250A (SWARM) Determined physical RAM map: memory: 000000000fe7fe00 @ 0000000000000000 (usable) memory: 000000001ffffe00 @ 0000000080000000 (usable) memory: 000000000ffffe00 @ 00000000c0000000 (usable) memory: 0000000087fffe00 @ 0000000100000000 (usable) software IO TLB: mapped [mem 0xcbffc000-0xcfffc000] (64MB)
in the bootstrap log and removes failures like these:
defxx 0000:02:00.0: dma_direct_map_page: overflow 0x0000000185bc6080+4608 of device mask ffffffff bus mask 0 fddi0: Receive buffer allocation failed fddi0: Adapter open failed! IP-Config: Failed to open fddi0 defxx 0000:09:08.0: dma_direct_map_page: overflow 0x0000000185bc6080+4608 of device mask ffffffff bus mask 0 fddi1: Receive buffer allocation failed fddi1: Adapter open failed! IP-Config: Failed to open fddi1
when memory beyond 4GiB is handed out to devices that can only do 32-bit addressing.
This updates commit cce335ae47e2 ("[MIPS] 64-bit Sibyte kernels need DMA32.").
References:
[1] "BCM1250/BCM1125/BCM1125H User Manual", Revision 1250_1125-UM100-R, Broadcom Corporation, 21 Oct 2002, Section 3: "System Overview", "Memory Map", pp. 34-38
[2] "BCM91250A User Manual", Revision 91250A-UM100-R, Broadcom Corporation, 18 May 2004, Section 3: "Physical Description", "Supported DRAM", p. 23
Signed-off-by: Maciej W. Rozycki macro@linux-mips.org [paul.burton@mips.com: Remove GPL text from dma.c; SPDX tag covers it] Signed-off-by: Paul Burton paul.burton@mips.com Reviewed-by: Christoph Hellwig hch@lst.de Patchwork: https://patchwork.linux-mips.org/patch/21108/ References: cce335ae47e2 ("[MIPS] 64-bit Sibyte kernels need DMA32.") Cc: Ralf Baechle ralf@linux-mips.org Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/mips/Kconfig | 3 +++ arch/mips/sibyte/common/Makefile | 1 + arch/mips/sibyte/common/dma.c | 14 ++++++++++++++ 3 files changed, 18 insertions(+) create mode 100644 arch/mips/sibyte/common/dma.c
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 35511999156a..b245e34bd97f 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -794,6 +794,7 @@ config SIBYTE_SWARM select SYS_SUPPORTS_HIGHMEM select SYS_SUPPORTS_LITTLE_ENDIAN select ZONE_DMA32 if 64BIT + select SWIOTLB if ARCH_DMA_ADDR_T_64BIT && PCI
config SIBYTE_LITTLESUR bool "Sibyte BCM91250C2-LittleSur" @@ -814,6 +815,7 @@ config SIBYTE_SENTOSA select SYS_HAS_CPU_SB1 select SYS_SUPPORTS_BIG_ENDIAN select SYS_SUPPORTS_LITTLE_ENDIAN + select SWIOTLB if ARCH_DMA_ADDR_T_64BIT && PCI
config SIBYTE_BIGSUR bool "Sibyte BCM91480B-BigSur" @@ -826,6 +828,7 @@ config SIBYTE_BIGSUR select SYS_SUPPORTS_HIGHMEM select SYS_SUPPORTS_LITTLE_ENDIAN select ZONE_DMA32 if 64BIT + select SWIOTLB if ARCH_DMA_ADDR_T_64BIT && PCI
config SNI_RM bool "SNI RM200/300/400" diff --git a/arch/mips/sibyte/common/Makefile b/arch/mips/sibyte/common/Makefile index b3d6bf23a662..3ef3fb658136 100644 --- a/arch/mips/sibyte/common/Makefile +++ b/arch/mips/sibyte/common/Makefile @@ -1,4 +1,5 @@ obj-y := cfe.o +obj-$(CONFIG_SWIOTLB) += dma.o obj-$(CONFIG_SIBYTE_BUS_WATCHER) += bus_watcher.o obj-$(CONFIG_SIBYTE_CFE_CONSOLE) += cfe_console.o obj-$(CONFIG_SIBYTE_TBPROF) += sb_tbprof.o diff --git a/arch/mips/sibyte/common/dma.c b/arch/mips/sibyte/common/dma.c new file mode 100644 index 000000000000..eb47a94f3583 --- /dev/null +++ b/arch/mips/sibyte/common/dma.c @@ -0,0 +1,14 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * DMA support for Broadcom SiByte platforms. + * + * Copyright (c) 2018 Maciej W. Rozycki + */ + +#include <linux/swiotlb.h> +#include <asm/bootinfo.h> + +void __init plat_swiotlb_setup(void) +{ + swiotlb_init(1); +}