[PATCH v2 2/8] clk: rockchip: Make calculations use rounding

[Heiko Stuebner]

From: Douglas Anderson <diand...@chromium.org>

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 <diand...@chromium.org>
Signed-off-by: Heiko Stuebner <he...@sntech.de>
---
 drivers/clk/rockchip/clk-mmc-phase.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/clk/rockchip/clk-mmc-phase.c 
b/drivers/clk/rockchip/clk-mmc-phase.c
index a797d86..bc24e5a 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;
-- 
2.5.1

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