From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/metag/mm/maccess.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 arch/metag/mm/maccess.c (limited to 'arch/metag/mm/maccess.c') diff --git a/arch/metag/mm/maccess.c b/arch/metag/mm/maccess.c new file mode 100644 index 000000000..eba2cfc93 --- /dev/null +++ b/arch/metag/mm/maccess.c @@ -0,0 +1,68 @@ +/* + * safe read and write memory routines callable while atomic + * + * Copyright 2012 Imagination Technologies + */ + +#include +#include + +/* + * The generic probe_kernel_write() uses the user copy code which can split the + * writes if the source is unaligned, and repeats writes to make exceptions + * precise. We override it here to avoid these things happening to memory mapped + * IO memory where they could have undesired effects. + * Due to the use of CACHERD instruction this only works on Meta2 onwards. + */ +#ifdef CONFIG_METAG_META21 +long probe_kernel_write(void *dst, const void *src, size_t size) +{ + unsigned long ldst = (unsigned long)dst; + void __iomem *iodst = (void __iomem *)dst; + unsigned long lsrc = (unsigned long)src; + const u8 *psrc = (u8 *)src; + unsigned int pte, i; + u8 bounce[8] __aligned(8); + + if (!size) + return 0; + + /* Use the write combine bit to decide is the destination is MMIO. */ + pte = __builtin_meta2_cacherd(dst); + + /* Check the mapping is valid and writeable. */ + if ((pte & (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT)) + != (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT)) + return -EFAULT; + + /* Fall back to generic version for cases we're not interested in. */ + if (pte & MMCU_ENTRY_WRC_BIT || /* write combined memory */ + (ldst & (size - 1)) || /* destination unaligned */ + size > 8 || /* more than max write size */ + (size & (size - 1))) /* non power of 2 size */ + return __probe_kernel_write(dst, src, size); + + /* If src is unaligned, copy to the aligned bounce buffer first. */ + if (lsrc & (size - 1)) { + for (i = 0; i < size; ++i) + bounce[i] = psrc[i]; + psrc = bounce; + } + + switch (size) { + case 1: + writeb(*psrc, iodst); + break; + case 2: + writew(*(const u16 *)psrc, iodst); + break; + case 4: + writel(*(const u32 *)psrc, iodst); + break; + case 8: + writeq(*(const u64 *)psrc, iodst); + break; + } + return 0; +} +#endif -- cgit v1.2.3-54-g00ecf