riscv: Fix udelay in RV32.

[ Upstream commit d0e1f2110a5eeb6e410b2dd37d98bc5b30da7bc7 ]

In RV32, udelay would delay the wrong cycle. When it shifts right
"UDELAY_SHIFT" bits, it either delays 0 cycle or 1 cycle. It only works
correctly in RV64. Because the 'ucycles' always needs to be 64 bits
variable.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
[paul.walmsley@sifive.com: fixed minor spelling error]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/lib/delay.c b/arch/riscv/lib/delay.c
index dce8ae2..ee6853c 100644 (file)
--- a/arch/riscv/lib/delay.c
+++ b/arch/riscv/lib/delay.c
@@ -88,7 +88,7 @@ EXPORT_SYMBOL(__delay);
 
 void udelay(unsigned long usecs)
 {
-       unsigned long ucycles = usecs * lpj_fine * UDELAY_MULT;
+       u64 ucycles = (u64)usecs * lpj_fine * UDELAY_MULT;
 
        if (unlikely(usecs > MAX_UDELAY_US)) {
                __delay((u64)usecs * riscv_timebase / 1000000ULL);