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From 929fdf6bd4f3dcbe4d545e920ec41437225b777f Mon Sep 17 00:00:00 2001
From: Remi Pommarel <repk@triplefau.lt>
Date: Sun, 6 Dec 2015 17:22:46 +0100
Subject: [PATCH] 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>
(cherry picked from commit 9c95b32ca09364e4687b72c4e17b78dc1c420026)
---
drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1166,22 +1166,24 @@ static int bcm2835_clock_is_on(struct cl
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 min divider of 1 */
div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS);
@@ -1221,7 +1223,7 @@ static long bcm2835_clock_round_rate(str
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);
}
@@ -1290,7 +1292,7 @@ static int bcm2835_clock_set_rate(struct
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);
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