clk: ti: add am33xx/am43xx spread spectrum clock support
The patch enables spread spectrum clocking (SSC) for MPU and LCD PLLs.
As reported by the TI spruh73x/spruhl7x RM, SSC is only supported for
the DISP/LCD and MPU PLLs on am33xx/am43xx. SSC is not supported for
DDR, PER, and CORE PLLs.
Calculating the required values and setting the registers accordingly
was taken from the set_mpu_spreadspectrum routine contained in the
arch/arm/mach-omap2/am33xx/clock_am33xx.c file of the u-boot project.
In locked condition, DPLL output clock = CLKINP *[M/N]. In case of
SSC enabled, the reference manual explains that there is a restriction
of range of M values. Since the clk_ti_am3_dpll_round_rate() attempts
to select the minimum possible N, the value of M obtained is not
guaranteed to be within the range required. With the new "ti,min-div"
parameter it is possible to increase N and consequently M to satisfy the
constraint imposed by SSC.
Link: https://lore.kernel.org/r/20210606202253.31649-6-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
diff --git a/arch/arm/include/asm/arch-am33xx/clock.h b/arch/arm/include/asm/arch-am33xx/clock.h
index 5d77590..79e3b8c 100644
--- a/arch/arm/include/asm/arch-am33xx/clock.h
+++ b/arch/arm/include/asm/arch-am33xx/clock.h
@@ -78,6 +78,18 @@
#define CM_CLKSEL_DPLL_N_SHIFT 0
#define CM_CLKSEL_DPLL_N_MASK 0x7F
+/* CM_SSC_DELTAM_DPLL */
+#define CM_SSC_DELTAM_DPLL_FRAC_SHIFT 0
+#define CM_SSC_DELTAM_DPLL_FRAC_MASK GENMASK(17, 0)
+#define CM_SSC_DELTAM_DPLL_INT_SHIFT 18
+#define CM_SSC_DELTAM_DPLL_INT_MASK GENMASK(19, 18)
+
+/* CM_SSC_MODFREQ_DPLL */
+#define CM_SSC_MODFREQ_DPLL_MANT_SHIFT 0
+#define CM_SSC_MODFREQ_DPLL_MANT_MASK GENMASK(6, 0)
+#define CM_SSC_MODFREQ_DPLL_EXP_SHIFT 7
+#define CM_SSC_MODFREQ_DPLL_EXP_MASK GENMASK(10, 8)
+
struct dpll_params {
u32 m;
u32 n;