rockchip/rk3399: enable DPLL SSC for DDR EMI test on bob
Spread Spectrum Modulator (SSMOD) is a fully-digital circuit used to
modulate the frequency of the Silicon Creations’ Fractional PLL in order
to reduce EMI.
We need to turn the DPLL spread spectrum feature on to
reduce the EMI noise for DDR on bob.
Change-Id: I75461d4235bcf55324e6664a1220754e770b4786
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Reviewed-on: https://review.coreboot.org/19557
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/src/soc/rockchip/rk3399/clock.c b/src/soc/rockchip/rk3399/clock.c
index eb413a1..944ca6f 100644
--- a/src/soc/rockchip/rk3399/clock.c
+++ b/src/soc/rockchip/rk3399/clock.c
@@ -82,8 +82,23 @@
PLL_MODE_DEEP,
PLL_DSMPD_MASK = 1,
PLL_DSMPD_SHIFT = 3,
+ PLL_FRAC_MODE = 0,
PLL_INTEGER_MODE = 1,
+ /* PLL_CON4 */
+ PLL_SSMOD_BP_MASK = 1,
+ PLL_SSMOD_BP_SHIFT = 0,
+ PLL_SSMOD_DIS_SSCG_MASK = 1,
+ PLL_SSMOD_DIS_SSCG_SHIFT = 1,
+ PLL_SSMOD_RESET_MASK = 1,
+ PLL_SSMOD_RESET_SHIFT = 2,
+ PLL_SSMOD_DOWNSPEAD_MASK = 1,
+ PLL_SSMOD_DOWNSPEAD_SHIFT = 3,
+ PLL_SSMOD_DIVVAL_MASK = 0Xf,
+ PLL_SSMOD_DIVVAL_SHIFT = 4,
+ PLL_SSMOD_SPREADAMP_MASK = 0x1f,
+ PLL_SSMOD_SPREADAMP_SHIFT = 8,
+
/* PMUCRU_CLKSEL_CON0 */
PMU_PCLK_DIV_CON_MASK = 0x1f,
PMU_PCLK_DIV_CON_SHIFT = 0,
@@ -326,6 +341,83 @@
PLL_MODE_NORM << PLL_MODE_SHIFT));
}
+/*
+ * Configure the DPLL spread spectrum feature on memory clock.
+ * Configure sequence:
+ * 1. PLL been configured as frac mode, and DACPD should be set to 1’b0.
+ * 2. Configure DOWNSPERAD, SPREAD, DIVVAL(option: configure xPLL_CON5 with
+ * extern wave table).
+ * 3. set ssmod_disable_sscg = 1’b0, and set ssmod_bp = 1’b0.
+ * 4. Assert RESET = 1’b1 to SSMOD.
+ * 5. RESET = 1’b0 on SSMOD.
+ * 6. Adjust SPREAD/DIVVAL/DOWNSPREAD.
+ */
+static void rkclk_set_dpllssc(struct pll_div *dpll_cfg)
+{
+ u32 divval;
+
+ /*
+ * TODO find the root cause why is the delay needed, otherwise sometimes
+ * hang somewhere with reboot tests.
+ */
+ udelay(30);
+ assert(dpll_cfg->refdiv && dpll_cfg->refdiv <= 6);
+
+ /*
+ * Need to acquire ~30kHZ which is the target modulation frequency.
+ * The modulation frequency ~ 30kHz= OSC_HZ/revdiv/128/divval
+ * (the 128 is the number points in the query table).
+ */
+ divval = OSC_HZ / 128 / (30 * KHz) / dpll_cfg->refdiv;
+
+ /*
+ * Use frac mode.
+ * Make sure the output frequency isn't offset, set 0 for Fractional
+ * part of feedback divide.
+ */
+ write32(&cru_ptr->dpll_con[3],
+ RK_CLRSETBITS(PLL_DSMPD_MASK << PLL_DSMPD_SHIFT,
+ PLL_FRAC_MODE << PLL_DSMPD_SHIFT));
+ clrsetbits_le32(&cru_ptr->dpll_con[2],
+ PLL_FRACDIV_MASK << PLL_FRACDIV_SHIFT,
+ 0 << PLL_FRACDIV_SHIFT);
+
+ /*
+ * Configure SSC divval.
+ * Spread amplitude range = 0.1 * SPREAD[4:0] (%).
+ * The below 8 means SPREAD[4:0] that appears to mitigate EMI on boards
+ * tested. Center and down spread modulation amplitudes based on the
+ * value of SPREAD.
+ * SPREAD[4:0] Center Spread Down Spread
+ * 0 0 0
+ * 1 ±0.1% -0.10%
+ * 2 ±0.2% -0.20%
+ * 3 ±0.3% -0.30%
+ * 4 ±0.4% -0.40%
+ * 5 ±0.5% -0.50%
+ * ...
+ * 31 ±3.1% -3.10%
+ */
+ write32(&cru_ptr->dpll_con[4],
+ RK_CLRSETBITS(PLL_SSMOD_DIVVAL_MASK << PLL_SSMOD_DIVVAL_SHIFT,
+ divval << PLL_SSMOD_DIVVAL_SHIFT));
+ write32(&cru_ptr->dpll_con[4],
+ RK_CLRSETBITS(PLL_SSMOD_SPREADAMP_MASK <<
+ PLL_SSMOD_SPREADAMP_SHIFT,
+ 8 << PLL_SSMOD_SPREADAMP_SHIFT));
+
+ /* Enable SSC for DPLL */
+ write32(&cru_ptr->dpll_con[4],
+ RK_CLRBITS(PLL_SSMOD_BP_MASK << PLL_SSMOD_BP_SHIFT |
+ PLL_SSMOD_DIS_SSCG_MASK << PLL_SSMOD_DIS_SSCG_SHIFT));
+
+ /* Deassert reset SSMOD */
+ write32(&cru_ptr->dpll_con[4],
+ RK_CLRBITS(PLL_SSMOD_RESET_MASK << PLL_SSMOD_RESET_SHIFT));
+
+ udelay(20);
+}
+
static int pll_para_config(u32 freq_hz, struct pll_div *div)
{
u32 ref_khz = OSC_HZ / KHz, refdiv, fbdiv = 0;
@@ -571,6 +663,9 @@
die("Unsupported SDRAM frequency, add to clock.c!");
}
rkclk_set_pll(&cru_ptr->dpll_con[0], &dpll_cfg);
+
+ if (IS_ENABLED(CONFIG_RK3399_SPREAD_SPECTRUM_DDR))
+ rkclk_set_dpllssc(&dpll_cfg);
}
#define SPI_CLK_REG_VALUE(bus, clk_div) \