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authorH. Peter Anvin <hpa@linux.intel.com>2014-02-07 11:27:30 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2014-02-07 11:27:30 -0800
commita3b072cd180c12e8fe0ece9487b9065808327640 (patch)
tree62b982041be84748852d77cdf6ca5639ef40858f /lib/reciprocal_div.c
parent75a1ba5b2c529db60ca49626bcaf0bddf4548438 (diff)
parent081cd62a010f97b5bc1d2b0cd123c5abc692b68a (diff)
downloadlinux-stericsson-a3b072cd180c12e8fe0ece9487b9065808327640.tar.gz
Merge tag 'efi-urgent' into x86/urgent
* Avoid WARN_ON() when mapping BGRT on Baytrail (EFI 32-bit). Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'lib/reciprocal_div.c')
-rw-r--r--lib/reciprocal_div.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/lib/reciprocal_div.c b/lib/reciprocal_div.c
index 75510e94f7d0..464152410c51 100644
--- a/lib/reciprocal_div.c
+++ b/lib/reciprocal_div.c
@@ -1,11 +1,27 @@
+#include <linux/kernel.h>
#include <asm/div64.h>
#include <linux/reciprocal_div.h>
#include <linux/export.h>
-u32 reciprocal_value(u32 k)
+/*
+ * For a description of the algorithm please have a look at
+ * include/linux/reciprocal_div.h
+ */
+
+struct reciprocal_value reciprocal_value(u32 d)
{
- u64 val = (1LL << 32) + (k - 1);
- do_div(val, k);
- return (u32)val;
+ struct reciprocal_value R;
+ u64 m;
+ int l;
+
+ l = fls(d - 1);
+ m = ((1ULL << 32) * ((1ULL << l) - d));
+ do_div(m, d);
+ ++m;
+ R.m = (u32)m;
+ R.sh1 = min(l, 1);
+ R.sh2 = max(l - 1, 0);
+
+ return R;
}
EXPORT_SYMBOL(reciprocal_value);