From e085a8a359a82bce204fe15325e1aead53aa3edd Mon Sep 17 00:00:00 2001 From: Caesar Wang Date: Thu, 4 May 2017 09:24:23 +0800 Subject: rockchip/rk3399: enable DPLL SSC for DDR EMI test on bob MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Caesar Wang Reviewed-on: https://review.coreboot.org/19557 Tested-by: build bot (Jenkins) Reviewed-by: Julius Werner --- src/soc/rockchip/rk3399/Kconfig | 8 ++++ src/soc/rockchip/rk3399/clock.c | 95 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+) (limited to 'src/soc/rockchip') 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) \ -- cgit v1.2.3