[PATCH] lib: sbi: Fix writes to emulated 32-bit htimedelta CSR

[Samuel Holland]

Writes to the low half CSR should not affect the high half of the value.
Make this separation explicit by writing to the delta in memory as two
adjacent XLEN-sized values.

Fixes: 1e9f88889f8b ("lib: Emulate HTIMEDELTA CSR for platforms not having TIME CSR")
Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
---

 include/sbi/sbi_timer.h |  2 ++
 lib/sbi/sbi_timer.c     | 15 ++++++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/include/sbi/sbi_timer.h b/include/sbi/sbi_timer.h
index ac48e2b8..ac2c7be5 100644
--- a/include/sbi/sbi_timer.h
+++ b/include/sbi/sbi_timer.h
@@ -78,8 +78,10 @@ u64 sbi_timer_get_delta(void);
 /** Set timer delta value for current HART */
 void sbi_timer_set_delta(ulong delta);
 
+#if __riscv_xlen == 32
 /** Set upper 32-bits of timer delta value for current HART */
 void sbi_timer_set_delta_upper(ulong delta_upper);
+#endif
 
 /** Start timer event for current HART */
 void sbi_timer_event_start(u64 next_event);
diff --git a/lib/sbi/sbi_timer.c b/lib/sbi/sbi_timer.c
index 7b618de1..32955183 100644
--- a/lib/sbi/sbi_timer.c
+++ b/lib/sbi/sbi_timer.c
@@ -114,20 +114,21 @@ u64 sbi_timer_get_delta(void)
 
 void sbi_timer_set_delta(ulong delta)
 {
-	u64 *time_delta = sbi_scratch_offset_ptr(sbi_scratch_thishart_ptr(),
-						 time_delta_off);
+	ulong *time_delta = sbi_scratch_offset_ptr(sbi_scratch_thishart_ptr(),
+						   time_delta_off);
 
-	*time_delta = (u64)delta;
+	*time_delta = delta;
 }
 
+#if __riscv_xlen == 32
 void sbi_timer_set_delta_upper(ulong delta_upper)
 {
-	u64 *time_delta = sbi_scratch_offset_ptr(sbi_scratch_thishart_ptr(),
-						 time_delta_off);
+	ulong *time_delta = sbi_scratch_offset_ptr(sbi_scratch_thishart_ptr(),
+						   time_delta_off);
 
-	*time_delta &= 0xffffffffULL;
-	*time_delta |= ((u64)delta_upper << 32);
+	*(time_delta + 1) = delta_upper;
 }
+#endif
 
 void sbi_timer_event_start(u64 next_event)
 {
-- 
2.45.1