This is a note to let you know that I've just added the patch titled
ARC: timer: rtc: implement read loop in "C" vs. inline asm
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-timer-rtc-implement-read-loop-in-c-vs.-inline-asm.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 922cc171998ac3dbe74d57011ef7ed57e9b0d7df Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Date: Mon, 31 Oct 2016 14:09:52 -0700
Subject: ARC: timer: rtc: implement read loop in "C" vs. inline asm
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
commit 922cc171998ac3dbe74d57011ef7ed57e9b0d7df upstream.
The current code doesn't even compile as somehow the inline assembly
can't see the register names defined as ARC_RTC_*
I'm pretty sure It worked when I first got it merged, but the tools were
definitely different then.
So better to write this in "C" anyways.
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/kernel/time.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/arch/arc/kernel/time.c
+++ b/arch/arc/kernel/time.c
@@ -130,14 +130,17 @@ static cycle_t arc_counter_read(struct c
cycle_t full;
} stamp;
-
- __asm__ __volatile(
- "1: \n"
- " lr %0, [AUX_RTC_LOW] \n"
- " lr %1, [AUX_RTC_HIGH] \n"
- " lr %2, [AUX_RTC_CTRL] \n"
- " bbit0.nt %2, 31, 1b \n"
- : "=r" (stamp.low), "=r" (stamp.high), "=r" (status));
+ /*
+ * hardware has an internal state machine which tracks readout of
+ * low/high and updates the CTRL.status if
+ * - interrupt/exception taken between the two reads
+ * - high increments after low has been read
+ */
+ do {
+ stamp.low = read_aux_reg(AUX_RTC_LOW);
+ stamp.high = read_aux_reg(AUX_RTC_HIGH);
+ status = read_aux_reg(AUX_RTC_CTRL);
+ } while (!(status & _BITUL(31)));
return stamp.full;
}
Patches currently in stable-queue which might be from vgupta@xxxxxxxxxxxx are
queue-4.4/arc-timer-rtc-implement-read-loop-in-c-vs.-inline-asm.patch
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