From: Yibo Cai <yibo.cai@xxxxxxx>
Get square root of a 64-bit digit on 32bit platforms. CSR SiRFSoC
touchscreen driver needs it.
Cc: Peter Meerwald <pmeerw@xxxxxxxxxx>
Signed-off-by: Yibo Cai <yibo.cai@xxxxxxx>
Signed-off-by: Barry Song <Baohua.Song@xxxxxxx>
---
-v2:
use CONFIG_64BIT MARCO
don't init for b, m
include/linux/kernel.h | 8 ++++++++
lib/int_sqrt.c | 25 +++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 4c52907..a536c0c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -418,6 +418,14 @@ struct pid;
extern struct pid *session_of_pgrp(struct pid *pgrp);
unsigned long int_sqrt(unsigned long);
+#ifdef CONFIG_64BIT
+static inline unsigned long long int64_sqrt(unsigned long long x)
+{
+ return int_sqrt(x);
+}
+#else
+unsigned long long int64_sqrt(unsigned long long);
+#endif
extern void bust_spinlocks(int yes);
extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */
diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 1ef4cc3..b86cccb 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -36,3 +36,28 @@ unsigned long int_sqrt(unsigned long x)
return y;
}
EXPORT_SYMBOL(int_sqrt);
+
+#ifndef CONFIG_64BIT
+unsigned long long int64_sqrt(unsigned long long x)
+{
+ unsigned long long b, m, y = 0;
+
+ if (x <= 1)
+ return x;
+
+ m = 1ULL << (BITS_PER_LONG_LONG - 2);
+ while (m != 0) {
+ b = y + m;
+ y >>= 1;
+
+ if (x >= b) {
+ x -= b;
+ y += m;
+ }
+ m >>= 2;
+ }
+
+ return y;
+}
+EXPORT_SYMBOL(int64_sqrt);
+#endif
--
1.9.3
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