ARM: OMAP5+: dpll: support Duty Cycle Correction(DCC)

Duty Cycle Correction(DCC) needs to be enabled if the MPU is to run at
frequencies beyond 1.4GHz for OMAP5, DRA75x, DRA72x.

MPU DPLL has a limitation on the maximum frequency it can be locked
at. Duty Cycle Correction circuit is used to recover a correct duty
cycle for achieving higher frequencies (hardware internally switches
output to M3 output(CLKOUTHIF) from M2 output (CLKOUT)).

For further information, See the note on OMAP5432 Technical Reference
Manual(SWPU282U) chapter 3.6.3.3.1 "DPLLs Output Clocks Parameters",
and also the "OMAP543x ES2.0 DM Operating Conditions Addendum v0.5"
chapter 2.1 "Micro Processor Unit (MPU)". Equivalent information is
present in relevant DRA75x, 72x documentation(SPRUHP2E, SPRUHI2P).

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
Signed-off-by: Taras Kondratiuk <taras@ti.com>
Signed-off-by: J Keerthy <j-keerthy@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
[t-kristo@ti.com: added TRM / DM references for DCC clock rate]
Signed-off-by: Tero Kristo <t-kristo@ti.com>

2 files changed, 13 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/dpll3xxx.c b/arch/arm/mach-omap2/dpll3xxx.c
index fcd8036af910..6d7ba37e2257 100644
--- a/arch/arm/mach-omap2/dpll3xxx.c
+++ b/arch/arm/mach-omap2/dpll3xxx.c
@@ -319,6 +319,15 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
 
         /* Set DPLL multiplier, divider */
         v = omap2_clk_readl(clk, dd->mult_div1_reg);
+
+        /* Handle Duty Cycle Correction */
+        if (dd->dcc_mask) {
+                if (dd->last_rounded_rate >= dd->dcc_rate)
+                        v |= dd->dcc_mask; /* Enable DCC */
+                else
+                        v &= ~dd->dcc_mask; /* Disable DCC */
+        }
+
         v &= ~(dd->mult_mask | dd->div1_mask);
         v |= dd->last_rounded_m << __ffs(dd->mult_mask);
         v |= (dd->last_rounded_n - 1) << __ffs(dd->div1_mask);
diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index 4231c41bed51..e8d8a35034a5 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -41,6 +41,8 @@
  * @idlest_reg: register containing the DPLL idle status bitfield
  * @autoidle_mask: mask of the DPLL autoidle mode bitfield in @autoidle_reg
  * @freqsel_mask: mask of the DPLL jitter correction bitfield in @control_reg
+ * @dcc_mask: mask of the DPLL DCC correction bitfield @mult_div1_reg
+ * @dcc_rate: rate atleast which DCC @dcc_mask must be set
  * @idlest_mask: mask of the DPLL idle status bitfield in @idlest_reg
  * @lpmode_mask: mask of the DPLL low-power mode bitfield in @control_reg
  * @m4xen_mask: mask of the DPLL M4X multiplier bitfield in @control_reg
@@ -86,6 +88,8 @@ struct dpll_data {
         u32                     idlest_mask;
         u32                     dco_mask;
         u32                     sddiv_mask;
+        u32                     dcc_mask;
+        unsigned long           dcc_rate;
         u32                     lpmode_mask;
         u32                     m4xen_mask;
         u8                      auto_recal_bit;