target/linux/brcm2708/patches-4.4/0252-clk-bcm2835-add-a-round-up-ability-to-the-clock-divi.patch

   1 From 78c280c96a984805dfa19969e927c17ccada808f Mon Sep 17 00:00:00 2001
   2 From: Remi Pommarel <repk@triplefau.lt>
   3 Date: Sun, 6 Dec 2015 17:22:46 +0100
   4 Subject: [PATCH 252/304] clk: bcm2835: add a round up ability to the clock
   5  divisor
   6
   7 Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor
   8 so that the resulting average rate will not be higher than the requested one.
   9
  10 Signed-off-by: Remi Pommarel <repk@triplefau.lt>
  11 Reviewed-by: Eric Anholt <eric@anholt.net>
  12 Signed-off-by: Michael Turquette <mturquette@baylibre.com>
  13 (cherry picked from commit 9c95b32ca09364e4687b72c4e17b78dc1c420026)
  14 ---
  15  drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++----------
  16  1 file changed, 12 insertions(+), 10 deletions(-)
  17
  18 --- a/drivers/clk/bcm/clk-bcm2835.c
  19 +++ b/drivers/clk/bcm/clk-bcm2835.c
  20 @@ -1150,22 +1150,24 @@ static int bcm2835_clock_is_on(struct cl
  21
  22  static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
  23                                     unsigned long rate,
  24 -                                   unsigned long parent_rate)
  25 +                                   unsigned long parent_rate,
  26 +                                   bool round_up)
  27  {
  28         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  29         const struct bcm2835_clock_data *data = clock->data;
  30 -       u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0);
  31 +       u32 unused_frac_mask =
  32 +               GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
  33         u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
  34 +       u64 rem;
  35         u32 div;
  36
  37 -       do_div(temp, rate);
  38 +       rem = do_div(temp, rate);
  39         div = temp;
  40
  41 -       /* Round and mask off the unused bits */
  42 -       if (unused_frac_mask != 0) {
  43 -               div += unused_frac_mask >> 1;
  44 -               div &= ~unused_frac_mask;
  45 -       }
  46 +       /* Round up and mask off the unused bits */
  47 +       if (round_up && ((div & unused_frac_mask) != 0 || rem != 0))
  48 +               div += unused_frac_mask + 1;
  49 +       div &= ~unused_frac_mask;
  50
  51         /* Clamp to the limits. */
  52         div = max(div, unused_frac_mask + 1);
  53 @@ -1204,7 +1206,7 @@ static long bcm2835_clock_round_rate(str
  54                                      unsigned long *parent_rate)
  55  {
  56         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  57 -       u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate);
  58 +       u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false);
  59
  60         return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div);
  61  }
  62 @@ -1273,7 +1275,7 @@ static int bcm2835_clock_set_rate(struct
  63         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  64         struct bcm2835_cprman *cprman = clock->cprman;
  65         const struct bcm2835_clock_data *data = clock->data;
  66 -       u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate);
  67 +       u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
  68
  69         cprman_write(cprman, data->div_reg, div);
  70