Messages in this thread Patch in this message | | | From | Derek Basehore <> | Subject | [PATCH 2/8] lib/iomap_copy: add __ioread64_copy() | Date | Fri, 12 Jan 2018 13:24:16 -0800 |
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Some drivers will want to read IO memory 64 bits at a time. Add an API for this.
The 64-bit vs. 32-bit behavior is the same as the existing __iowrite64_copy(), where we don't expect to need to (or be able to) write in 64-bit chunks, so we fall back to a 32-bit equivalent.
Change-Id: Ia681f60bb98a0c6107052bccbeb5032861a93a0b Signed-off-by: Derek Basehore <dbasehore@chromium.org> Signed-off-by: Brian Norris <briannorris@chromium.org> --- include/linux/io.h | 1 + lib/iomap_copy.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/linux/io.h b/include/linux/io.h index 32e30e8fb9db..53c34a0d65f7 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -31,6 +31,7 @@ struct resource; __visible void __iowrite32_copy(void __iomem *to, const void *from, size_t count); void __ioread32_copy(void *to, const void __iomem *from, size_t count); void __iowrite64_copy(void __iomem *to, const void *from, size_t count); +void __ioread64_copy(void *to, const void __iomem *from, size_t count); #ifdef CONFIG_MMU int ioremap_page_range(unsigned long addr, unsigned long end, diff --git a/lib/iomap_copy.c b/lib/iomap_copy.c index b8f1d6cbb200..71c137ede5fb 100644 --- a/lib/iomap_copy.c +++ b/lib/iomap_copy.c @@ -89,3 +89,29 @@ void __attribute__((weak)) __iowrite64_copy(void __iomem *to, } EXPORT_SYMBOL_GPL(__iowrite64_copy); + +/** + * __ioread64_copy - copy data from MMIO space, in 64-bit units + * @to: destination (must be 64-bit aligned) + * @from: source, in MMIO space (must be 64-bit aligned) + * @count: number of 64-bit quantities to copy + * + * Copy data from MMIO space to kernel space, in units of 64 bits at a time if + * on a 64-bit system. 32-bit systems will fall back to 32 bits at a time. + * Order of access is not guaranteed, nor is a memory barrier performed + * afterwards. + */ +void __ioread64_copy(void *to, const void __iomem *from, size_t count) +{ +#ifdef CONFIG_64BIT + u64 *dst = to; + const u64 __iomem *src = from; + const u64 __iomem *end = src + count; + + while (src < end) + *dst++ = __raw_readq(src++); +#else + __ioread32_copy(to, from, count * 2); +#endif +} +EXPORT_SYMBOL_GPL(__ioread64_copy); -- 2.16.0.rc1.238.g530d649a79-goog
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