lib/iomap_copy.c: add __ioread32_copy()

Some drivers need to read data out of iomem areas 32-bits at a time. Add an API to do this. Signed-off-by: Stephen Boyd <[email protected]> Cc: Bjorn Andersson <[email protected]> Cc: <[email protected]> Cc: David Howells <[email protected]> Cc: Hauke Mehrtens <[email protected]> Cc: Paul Walmsley <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
majek · Jan 21, 2016 · a9aec58 · a9aec58
1 parent ef5c16b
commit a9aec58
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diff --git a/include/linux/io.h b/include/linux/io.h
@@ -29,6 +29,7 @@ struct device;
 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);
 
 #ifdef CONFIG_MMU

diff --git a/lib/iomap_copy.c b/lib/iomap_copy.c
@@ -41,6 +41,27 @@ void __attribute__((weak)) __iowrite32_copy(void __iomem *to,
 }
 EXPORT_SYMBOL_GPL(__iowrite32_copy);
 
+/**
+ * __ioread32_copy - copy data from MMIO space, in 32-bit units
+ * @to: destination (must be 32-bit aligned)
+ * @from: source, in MMIO space (must be 32-bit aligned)
+ * @count: number of 32-bit quantities to copy
+ *
+ * Copy data from MMIO space to kernel space, in units of 32 bits at a
+ * time.  Order of access is not guaranteed, nor is a memory barrier
+ * performed afterwards.
+ */
+void __ioread32_copy(void *to, const void __iomem *from, size_t count)
+{
+	u32 *dst = to;
+	const u32 __iomem *src = from;
+	const u32 __iomem *end = src + count;
+
+	while (src < end)
+		*dst++ = __raw_readl(src++);
+}
+EXPORT_SYMBOL_GPL(__ioread32_copy);
+
 /**
  * __iowrite64_copy - copy data to MMIO space, in 64-bit or 32-bit units
  * @to: destination, in MMIO space (must be 64-bit aligned)