From 2475ff9d2c6ea3bbfed55c4635426c371f9ad327 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Tue, 23 Oct 2012 14:55:08 +0100 Subject: arm64: Add simple earlyprintk support This patch adds support for "earlyprintk=" parameter on the kernel command line. The format is: earlyprintk=[,][,] where is the name of the (UART) device, e.g. "pl011", is the I/O address. The aren't currently used. The mapping of the earlyprintk device is done very early during kernel boot and there are restrictions on which functions it can call. A special early_io_map() function is added which creates the mapping from the pre-defined EARLY_IOBASE to the device I/O address passed via the kernel parameter. The pgd entry corresponding to EARLY_IOBASE is pre-populated in head.S during kernel boot. Only PL011 is currently supported and it is assumed that the interface is already initialised by the boot loader before the kernel is started. Signed-off-by: Catalin Marinas Acked-by: Arnd Bergmann --- arch/arm64/include/asm/io.h | 3 +++ arch/arm64/include/asm/memory.h | 1 + arch/arm64/include/asm/mmu.h | 1 + 3 files changed, 5 insertions(+) (limited to 'arch/arm64/include') diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index d2f05a6..57f12c9 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -230,6 +230,9 @@ extern void __iounmap(volatile void __iomem *addr); #define ioremap_wc(addr, size) __ioremap((addr), (size), __pgprot(PROT_NORMAL_NC)) #define iounmap __iounmap +#define PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF) +#define PROT_SECT_DEVICE_nGnRE (PROT_SECT_DEFAULT | PTE_PXN | PTE_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE)) + #define ARCH_HAS_IOREMAP_WC #include diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 1cac16a..381f556 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -43,6 +43,7 @@ #define PAGE_OFFSET UL(0xffffffc000000000) #define MODULES_END (PAGE_OFFSET) #define MODULES_VADDR (MODULES_END - SZ_64M) +#define EARLYCON_IOBASE (MODULES_VADDR - SZ_4M) #define VA_BITS (39) #define TASK_SIZE_64 (UL(1) << VA_BITS) diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index d4f7fd5..2494fc0 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -26,5 +26,6 @@ typedef struct { extern void paging_init(void); extern void setup_mm_for_reboot(void); +extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); #endif -- cgit v1.1