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authorChristoph Hellwig <hch@lst.de>2019-08-21 23:58:36 +0900
committerPaul Walmsley <paul.walmsley@sifive.com>2019-09-05 01:52:46 -0700
commit2f12dbf190d97dc0f2f8a07269dd0d8060808539 (patch)
treed699e8fc51c7814904c0ab79c50a7144e243d544 /arch/riscv
parentf5bf645d10f2c6cc85294021af70f2b7bcc42d8e (diff)
downloadlinux-2f12dbf190d97dc0f2f8a07269dd0d8060808539.tar.bz2
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>
Diffstat (limited to 'arch/riscv')
-rw-r--r--arch/riscv/include/asm/timex.h44
1 files changed, 21 insertions, 23 deletions
diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h
index 6a703ec9d796..c7ef131b9e4c 100644
--- a/arch/riscv/include/asm/timex.h
+++ b/arch/riscv/include/asm/timex.h
@@ -6,43 +6,41 @@
#ifndef _ASM_RISCV_TIMEX_H
#define _ASM_RISCV_TIMEX_H
-#include <asm/param.h>
+#include <asm/csr.h>
typedef unsigned long cycles_t;
-static inline cycles_t get_cycles_inline(void)
+static inline cycles_t get_cycles(void)
{
- cycles_t n;
-
- __asm__ __volatile__ (
- "rdtime %0"
- : "=r" (n));
- return n;
+ return csr_read(CSR_TIME);
}
-#define get_cycles get_cycles_inline
+#define get_cycles get_cycles
#ifdef CONFIG_64BIT
-static inline uint64_t get_cycles64(void)
+static inline u64 get_cycles64(void)
+{
+ return get_cycles();
+}
+#else /* CONFIG_64BIT */
+static inline u32 get_cycles_hi(void)
{
- return get_cycles();
+ return csr_read(CSR_TIMEH);
}
-#else
-static inline uint64_t get_cycles64(void)
+
+static inline u64 get_cycles64(void)
{
- u32 lo, hi, tmp;
- __asm__ __volatile__ (
- "1:\n"
- "rdtimeh %0\n"
- "rdtime %1\n"
- "rdtimeh %2\n"
- "bne %0, %2, 1b"
- : "=&r" (hi), "=&r" (lo), "=&r" (tmp));
+ u32 hi, lo;
+
+ do {
+ hi = get_cycles_hi();
+ lo = get_cycles();
+ } while (hi != get_cycles_hi());
+
return ((u64)hi << 32) | lo;
}
-#endif
+#endif /* CONFIG_64BIT */
#define ARCH_HAS_READ_CURRENT_TIMER
-
static inline int read_current_timer(unsigned long *timer_val)
{
*timer_val = get_cycles();