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authorRemi Pommarel <repk@triplefau.lt>2015-12-06 17:22:46 +0100
committerMichael Turquette <mturquette@baylibre.com>2015-12-24 20:38:06 -0800
commit9c95b32ca09364e4687b72c4e17b78dc1c420026 (patch)
tree2bed5fd0556a5023585d0a9c58006ba78edff4bd /drivers/clk/bcm
parent5e63dcc74b3066659ea53aeefbee1fc1d79f4b6f (diff)
clk: bcm2835: add a round up ability to the clock divisor
Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor so that the resulting average rate will not be higher than the requested one. Signed-off-by: Remi Pommarel <repk@triplefau.lt> Reviewed-by: Eric Anholt <eric@anholt.net> Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Diffstat (limited to 'drivers/clk/bcm')
-rw-r--r--drivers/clk/bcm/clk-bcm2835.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 39bf5820297e..9e881eef3c36 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1148,22 +1148,24 @@ static int bcm2835_clock_is_on(struct clk_hw *hw)
static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
unsigned long rate,
- unsigned long parent_rate)
+ unsigned long parent_rate,
+ bool round_up)
{
struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
const struct bcm2835_clock_data *data = clock->data;
- u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0);
+ u32 unused_frac_mask =
+ GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
+ u64 rem;
u32 div;
- do_div(temp, rate);
+ rem = do_div(temp, rate);
div = temp;
- /* Round and mask off the unused bits */
- if (unused_frac_mask != 0) {
- div += unused_frac_mask >> 1;
- div &= ~unused_frac_mask;
- }
+ /* Round up and mask off the unused bits */
+ if (round_up && ((div & unused_frac_mask) != 0 || rem != 0))
+ div += unused_frac_mask + 1;
+ div &= ~unused_frac_mask;
/* Clamp to the limits. */
div = max(div, unused_frac_mask + 1);
@@ -1202,7 +1204,7 @@ static long bcm2835_clock_round_rate(struct clk_hw *hw,
unsigned long *parent_rate)
{
struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
- u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate);
+ u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false);
return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div);
}
@@ -1271,7 +1273,7 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,
struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
struct bcm2835_cprman *cprman = clock->cprman;
const struct bcm2835_clock_data *data = clock->data;
- u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate);
+ u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
cprman_write(cprman, data->div_reg, div);