This function was added to the mainline kernel in commit eb18cba7
"math64: New separate div64_u64_rem helper" and is now used the virtual
video test driver.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
backport/backport-include/linux/math64.h | 27 ++++++++++++++++++++
backport/compat/backport-3.12.c | 43 ++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+)
create mode 100644 backport/backport-include/linux/math64.h
diff --git a/backport/backport-include/linux/math64.h b/backport/backport-include/linux/math64.h
new file mode 100644
index 0000000..2fbde06
--- /dev/null
+++ b/backport/backport-include/linux/math64.h
@@ -0,0 +1,27 @@
+#ifndef __BACKPORT_LINUX_MATH64_H
+#define __BACKPORT_LINUX_MATH64_H
+#include_next <linux/math64.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,12,0)
+
+#if BITS_PER_LONG == 64
+/**
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
+ */
+#define div64_u64_rem LINUX_BACKPORT(div64_u64_rem)
+static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
+{
+ *remainder = dividend % divisor;
+ return dividend / divisor;
+}
+#elif BITS_PER_LONG == 32
+#ifndef div64_u64_rem
+#define div64_u64_rem LINUX_BACKPORT(div64_u64_rem)
+#define backports_div64_u64_rem_add 1
+extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
+#endif
+
+#endif /* BITS_PER_LONG */
+#endif /* < 3.12 */
+
+#endif /* __BACKPORT_LINUX_MATH64_H */
diff --git a/backport/compat/backport-3.12.c b/backport/compat/backport-3.12.c
index 7e3dc58..c9b21e8 100644
--- a/backport/compat/backport-3.12.c
+++ b/backport/compat/backport-3.12.c
@@ -11,6 +11,7 @@
#include <linux/export.h>
#include <linux/hid.h>
#include <linux/bug.h>
+#include <linux/math64.h>
/*
* Allocator for buffer that is going to be passed to hid_output_report()
@@ -27,3 +28,45 @@ u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags)
return kmalloc(len, flags);
}
EXPORT_SYMBOL_GPL(hid_alloc_report_buf);
+
+#if BITS_PER_LONG == 32
+/**
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
+ * @dividend: 64bit dividend
+ * @divisor: 64bit divisor
+ * @remainder: 64bit remainder
+ *
+ * This implementation is a comparable to algorithm used by div64_u64.
+ * But this operation, which includes math for calculating the remainder,
+ * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
+ * systems.
+ */
+#ifndef backports_div64_u64_rem_add
+u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
+{
+ u32 high = divisor >> 32;
+ u64 quot;
+
+ if (high == 0) {
+ u32 rem32;
+ quot = div_u64_rem(dividend, divisor, &rem32);
+ *remainder = rem32;
+ } else {
+ int n = 1 + fls(high);
+ quot = div_u64(dividend >> n, divisor >> n);
+
+ if (quot != 0)
+ quot--;
+
+ *remainder = dividend - quot * divisor;
+ if (*remainder >= divisor) {
+ quot++;
+ *remainder -= divisor;
+ }
+ }
+
+ return quot;
+}
+EXPORT_SYMBOL_GPL(div64_u64_rem);
+#endif /* backports_div64_u64_rem_add */
+#endif /* BITS_PER_LONG */
--
2.7.0
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