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

   1 From 01993e1dda68d85ff6cf11cab6051bcefa46d2c1 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] clk: bcm2835: add a round up ability to the clock divisor
   5
   6 Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor
   7 so that the resulting average rate will not be higher than the requested one.
   8
   9 Signed-off-by: Remi Pommarel <repk@triplefau.lt>
  10 Reviewed-by: Eric Anholt <eric@anholt.net>
  11 Signed-off-by: Michael Turquette <mturquette@baylibre.com>
  12 (cherry picked from commit 9c95b32ca09364e4687b72c4e17b78dc1c420026)
  13 ---
  14  drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++----------
  15  1 file changed, 12 insertions(+), 10 deletions(-)
  16
  17 --- a/drivers/clk/bcm/clk-bcm2835.c
  18 +++ b/drivers/clk/bcm/clk-bcm2835.c
  19 @@ -1164,22 +1164,24 @@ static int bcm2835_clock_is_on(struct cl
  20
  21  static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
  22                                     unsigned long rate,
  23 -                                   unsigned long parent_rate)
  24 +                                   unsigned long parent_rate,
  25 +                                   bool round_up)
  26  {
  27         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  28         const struct bcm2835_clock_data *data = clock->data;
  29 -       u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0);
  30 +       u32 unused_frac_mask =
  31 +               GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
  32         u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
  33 +       u64 rem;
  34         u32 div;
  35
  36 -       do_div(temp, rate);
  37 +       rem = do_div(temp, rate);
  38         div = temp;
  39
  40 -       /* Round and mask off the unused bits */
  41 -       if (unused_frac_mask != 0) {
  42 -               div += unused_frac_mask >> 1;
  43 -               div &= ~unused_frac_mask;
  44 -       }
  45 +       /* Round up and mask off the unused bits */
  46 +       if (round_up && ((div & unused_frac_mask) != 0 || rem != 0))
  47 +               div += unused_frac_mask + 1;
  48 +       div &= ~unused_frac_mask;
  49
  50         /* clamp to min divider of 1 */
  51         div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS);
  52 @@ -1219,7 +1221,7 @@ static long bcm2835_clock_round_rate(str
  53                                      unsigned long *parent_rate)
  54  {
  55         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  56 -       u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate);
  57 +       u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false);
  58
  59         return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div);
  60  }
  61 @@ -1288,7 +1290,7 @@ static int bcm2835_clock_set_rate(struct
  62         struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
  63         struct bcm2835_cprman *cprman = clock->cprman;
  64         const struct bcm2835_clock_data *data = clock->data;
  65 -       u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate);
  66 +       u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
  67
  68         cprman_write(cprman, data->div_reg, div);
  69