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71 lines
2.5 KiB
Diff
71 lines
2.5 KiB
Diff
From 78c280c96a984805dfa19969e927c17ccada808f Mon Sep 17 00:00:00 2001
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From: Remi Pommarel <repk@triplefau.lt>
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Date: Sun, 6 Dec 2015 17:22:46 +0100
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Subject: [PATCH 252/304] clk: bcm2835: add a round up ability to the clock
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divisor
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Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor
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so that the resulting average rate will not be higher than the requested one.
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Signed-off-by: Remi Pommarel <repk@triplefau.lt>
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Reviewed-by: Eric Anholt <eric@anholt.net>
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Signed-off-by: Michael Turquette <mturquette@baylibre.com>
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(cherry picked from commit 9c95b32ca09364e4687b72c4e17b78dc1c420026)
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---
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drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++----------
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1 file changed, 12 insertions(+), 10 deletions(-)
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--- a/drivers/clk/bcm/clk-bcm2835.c
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+++ b/drivers/clk/bcm/clk-bcm2835.c
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@@ -1154,22 +1154,24 @@ static int bcm2835_clock_is_on(struct cl
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static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
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unsigned long rate,
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- unsigned long parent_rate)
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+ unsigned long parent_rate,
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+ bool round_up)
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{
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struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
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const struct bcm2835_clock_data *data = clock->data;
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- u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0);
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+ u32 unused_frac_mask =
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+ GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
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u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
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+ u64 rem;
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u32 div;
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- do_div(temp, rate);
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+ rem = do_div(temp, rate);
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div = temp;
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- /* Round and mask off the unused bits */
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- if (unused_frac_mask != 0) {
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- div += unused_frac_mask >> 1;
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- div &= ~unused_frac_mask;
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- }
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+ /* Round up and mask off the unused bits */
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+ if (round_up && ((div & unused_frac_mask) != 0 || rem != 0))
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+ div += unused_frac_mask + 1;
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+ div &= ~unused_frac_mask;
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/* Clamp to the limits. */
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div = max(div, unused_frac_mask + 1);
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@@ -1208,7 +1210,7 @@ static long bcm2835_clock_round_rate(str
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unsigned long *parent_rate)
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{
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struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
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- u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate);
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+ u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false);
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return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div);
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}
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@@ -1277,7 +1279,7 @@ static int bcm2835_clock_set_rate(struct
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struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
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struct bcm2835_cprman *cprman = clock->cprman;
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const struct bcm2835_clock_data *data = clock->data;
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- u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate);
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+ u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
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cprman_write(cprman, data->div_reg, div);
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