Re: [RFT PATCH v3 11/27] arm64: Implement ioremap_np() to map MMIO as nGnRnE
From: Will Deacon <will@kernel.org>
Date: 2021-03-24 18:18:54
Also in:
linux-arch, linux-arm-kernel, linux-devicetree, linux-samsung-soc, linux-serial, lkml
On Fri, Mar 05, 2021 at 06:38:46AM +0900, Hector Martin wrote:
quoted hunk ↗ jump to hunk
This is used on Apple ARM platforms, which require most MMIO (except PCI devices) to be mapped as nGnRnE. Signed-off-by: Hector Martin <redacted> --- arch/arm64/include/asm/io.h | 1 + 1 file changed, 1 insertion(+)diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 5ea8656a2030..953b8703af60 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h@@ -169,6 +169,7 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size); #define ioremap(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE)) #define ioremap_wc(addr, size) __ioremap((addr), (size), __pgprot(PROT_NORMAL_NC)) +#define ioremap_np(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRnE))
Probably worth noting that whether or not this actually results in a non-posted mapping depends on the system architecture, but this is the best we can do, so: Acked-by: Will Deacon <will@kernel.org> I would personally prefer that drivers didn't have to care about this, and ioremap on arm64 figured out the right attributes based on the region being mapped, but I haven't followed the discussion closely so I won't die on that hill. Will