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>

diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
index 30335d3b99afb197332505d5be045f2d5d75be4c..48c5298b6bb178e6a12f9022f2fe9d0980635541 100644 (file)
--- a/drivers/clk/clk-si5351.c
+++ b/drivers/clk/clk-si5351.c
@@ -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;