diff options
Diffstat (limited to 'src/soc/rockchip/rk3399')
| -rw-r--r-- | src/soc/rockchip/rk3399/Kconfig | 8 | ||||
| -rw-r--r-- | src/soc/rockchip/rk3399/clock.c | 95 |
2 files changed, 103 insertions, 0 deletions
diff --git a/src/soc/rockchip/rk3399/Kconfig b/src/soc/rockchip/rk3399/Kconfig index 65b31d523e..ff857c022c 100644 --- a/src/soc/rockchip/rk3399/Kconfig +++ b/src/soc/rockchip/rk3399/Kconfig @@ -24,4 +24,12 @@ config PMIC_BUS int default -1 +config RK3399_SPREAD_SPECTRUM_DDR + bool "Spread-spectrum DDR clock" + default n + help + Select 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. + endif diff --git a/src/soc/rockchip/rk3399/clock.c b/src/soc/rockchip/rk3399/clock.c index eb413a1329..944ca6f417 100644 --- a/src/soc/rockchip/rk3399/clock.c +++ b/src/soc/rockchip/rk3399/clock.c @@ -82,8 +82,23 @@ enum { 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 @@ static void rkclk_set_pll(u32 *pll_con, const struct pll_div *div) 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 @@ void rkclk_configure_ddr(unsigned int hz) 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) \ |