clk: rockchip: Make calculations use rounding

Let's use DIV_ROUND_CLOSEST for rounding, not just truncating
division.  This lets us get closer to the right rate.

Before this:
  set_phase(86) delay_nums=26 reg[0xf000420c]=0x468 actual_degrees=83
  set_phase(89) delay_nums=27 reg[0xf000420c]=0x46c actual_degrees=86

After this:
  set_phase(86) delay_nums=27 reg[0xf000420c]=0x46c actual_degrees=86
  set_phase(89) delay_nums=28 reg[0xf000420c]=0x470 actual_degrees=90

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/clk/rockchip/clk-mmc-phase.c b/drivers/clk/rockchip/clk-mmc-phase.c
index a797d8625f6d..bc24e5a002e7 100644
--- a/drivers/clk/rockchip/clk-mmc-phase.c
+++ b/drivers/clk/rockchip/clk-mmc-phase.c
@@ -69,7 +69,7 @@ static int rockchip_mmc_get_phase(struct clk_hw *hw)
 
                 delay_num = (raw_value & ROCKCHIP_MMC_DELAYNUM_MASK);
                 delay_num >>= ROCKCHIP_MMC_DELAYNUM_OFFSET;
-                degrees += delay_num * factor / 10000;
+                degrees += DIV_ROUND_CLOSEST(delay_num * factor, 10000);
         }
 
         return degrees % 360;
@@ -82,7 +82,7 @@ static int rockchip_mmc_set_phase(struct clk_hw *hw, int degrees)
         u8 nineties, remainder;
         u8 delay_num;
         u32 raw_value;
-        u64 delay;
+        u32 delay;
 
         nineties = degrees / 90;
         remainder = (degrees % 90);
@@ -110,12 +110,13 @@ static int rockchip_mmc_set_phase(struct clk_hw *hw, int degrees)
          * Convert to delay; do a little extra work to make sure we
          * don't overflow 32-bit / 64-bit numbers.
          */
-        delay = PSECS_PER_SEC;
+        delay = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
         delay *= remainder;
-        do_div(delay, 10000);
-        do_div(delay, (rate / 1000) * 36 * ROCKCHIP_MMC_DELAY_ELEMENT_PSEC);
+        delay = DIV_ROUND_CLOSEST(delay,
+                        (rate / 1000) * 36 *
+                                (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
 
-        delay_num = (u8) min(delay, 255ULL);
+        delay_num = (u8) min_t(u32, delay, 255);
 
         raw_value = delay_num ? ROCKCHIP_MMC_DELAY_SEL : 0;
         raw_value |= delay_num << ROCKCHIP_MMC_DELAYNUM_OFFSET;