From 2f12dbf190d97dc0f2f8a07269dd0d8060808539 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 21 Aug 2019 23:58:36 +0900
Subject: riscv: don't use the rdtime(h) pseudo-instructions
If we just use the CSRs that these map to directly the code is simpler
and doesn't require extra inline assembly code. Also fix up the top-level
comment in timer-riscv.c to not talk about the cycle count or mention
details of the clocksource interface, of which this file is just a
consumer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
---
drivers/clocksource/timer-riscv.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)
(limited to 'drivers/clocksource/timer-riscv.c')
diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index 09e031176bc6..470c7ef02ea4 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -2,6 +2,10 @@
/*
* Copyright (C) 2012 Regents of the University of California
* Copyright (C) 2017 SiFive
+ *
+ * All RISC-V systems have a timer attached to every hart. These timers can be
+ * read from the "time" and "timeh" CSRs, and can use the SBI to setup
+ * events.
*/
#include <linux/clocksource.h>
#include <linux/clockchips.h>
@@ -12,19 +16,6 @@
#include <asm/smp.h>
#include <asm/sbi.h>
-/*
- * All RISC-V systems have a timer attached to every hart. These timers can be
- * read by the 'rdcycle' pseudo instruction, and can use the SBI to setup
- * events. In order to abstract the architecture-specific timer reading and
- * setting functions away from the clock event insertion code, we provide
- * function pointers to the clockevent subsystem that perform two basic
- * operations: rdtime() reads the timer on the current CPU, and
- * next_event(delta) sets the next timer event to 'delta' cycles in the future.
- * As the timers are inherently a per-cpu resource, these callbacks perform
- * operations on the current hart. There is guaranteed to be exactly one timer
- * per hart on all RISC-V systems.
- */
-
static int riscv_clock_next_event(unsigned long delta,
struct clock_event_device *ce)
{
--
cgit