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clk: si5351: fix .round_rate for multisynth 6-7 

The divider calculation for multisynth 6 and 7 differs from the
calculation for multisynth 0-5.

For MS6 and MS7, set MSx_P1 directly, MSx_P1=divide value
[AN619, p. 6].

Referenced document:
[AN619] Manually Generating an Si5351 Register Map, Rev. 0.4

Signed-off-by: Sergej Sawazki <ce3a@gmx.de>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
This commit is contained in:
Sergej Sawazki 2015-05-11 10:44:50 +02:00 committed by Michael Turquette
parent 8157356015
commit 2073b5e909
1 changed files with 17 additions and 4 deletions
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21
drivers/clk/clk-si5351.c
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@ -552,7 +552,8 @@ static const struct clk_ops si5351_pll_ops = {
* MSx_P2[19:0] = 128 * b - c * floor(128 * b/c) = (128*b) mod c
* MSx_P3[19:0] = c
*
* MS[6,7] are integer (P1) divide only, P2 = 0, P3 = 0
* MS[6,7] are integer (P1) divide only, P1 = divide value,
* P2 and P3 are not applicable
*
* for 150MHz < fOUT <= 160MHz:
*
@ -679,6 +680,16 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
c = 1;
*parent_rate = a * rate;
} else if (hwdata->num >= 6) {
/* determine the closest integer divider */
a = DIV_ROUND_CLOSEST(*parent_rate, rate);
if (a < SI5351_MULTISYNTH_A_MIN)
a = SI5351_MULTISYNTH_A_MIN;
if (a > SI5351_MULTISYNTH67_A_MAX)
a = SI5351_MULTISYNTH67_A_MAX;
b = 0;
c = 1;
} else {
unsigned long rfrac, denom;
@ -692,9 +703,7 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
a = *parent_rate / rate;
if (a < SI5351_MULTISYNTH_A_MIN)
a = SI5351_MULTISYNTH_A_MIN;
if (hwdata->num >= 6 && a > SI5351_MULTISYNTH67_A_MAX)
a = SI5351_MULTISYNTH67_A_MAX;
else if (a > SI5351_MULTISYNTH_A_MAX)
if (a > SI5351_MULTISYNTH_A_MAX)
a = SI5351_MULTISYNTH_A_MAX;
/* find best approximation for b/c = fVCO mod fOUT */
@ -723,6 +732,10 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
hwdata->params.p3 = 1;
hwdata->params.p2 = 0;
hwdata->params.p1 = 0;
} else if (hwdata->num >= 6) {
hwdata->params.p3 = 0;
hwdata->params.p2 = 0;
hwdata->params.p1 = a;
} else {
hwdata->params.p3 = c;
hwdata->params.p2 = (128 * b) % c;