[PATCH v2 3/4] clk: imx: pll14xx: support spread spectrum clock generation

Peng Fan (OSS)
2025-02-05T09:51:06Z

From: Peng Fan <peng.fan@nxp.com>

Add support for spread spectrum clock (SSC) generation to the pll14xxx
driver.

Co-developed-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
drivers/clk/imx/clk-pll14xx.c | 66 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)

diff --git a/drivers/clk/imx/clk-pll14xx.c b/drivers/clk/imx/clk-pll14xx.c
index f290981ea13bdba3602af7aa44aaadfe0b78dcf9..3bdce762a9d651a6fb048dcbf58db396af9d3aaf 100644
--- a/drivers/clk/imx/clk-pll14xx.c
+++ b/drivers/clk/imx/clk-pll14xx.c
@@ -20,6 +20,8 @@
#define GNRL_CTL 0x0
#define DIV_CTL0 0x4
#define DIV_CTL1 0x8
+#define SSCG_CTRL 0xc
+
#define LOCK_STATUS BIT(31)
#define LOCK_SEL_MASK BIT(29)
#define CLKE_MASK BIT(11)
@@ -31,15 +33,26 @@
#define KDIV_MASK GENMASK(15, 0)
#define KDIV_MIN SHRT_MIN
#define KDIV_MAX SHRT_MAX
+#define SSCG_ENABLE BIT(31)
+#define MFREQ_CTL_MASK GENMASK(19, 12)
+#define MRAT_CTL_MASK GENMASK(9, 4)
+#define SEL_PF_MASK GENMASK(1, 0)

#define LOCK_TIMEOUT_US 10000

+enum imx_pll14xx_ssc_mod_type {
+ IMX_PLL14XX_SSC_DOWN_SPREAD,
+ IMX_PLL14XX_SSC_UP_SPREAD,
+ IMX_PLL14XX_SSC_CENTER_SPREAD,
+};
+
struct clk_pll14xx {
struct clk_hw hw;
void __iomem *base;
enum imx_pll14xx_type type;
const struct imx_pll14xx_rate_table *rate_table;
int rate_count;
+ struct clk_spread_spectrum ssc_conf;
};

#define to_clk_pll14xx(_hw) container_of(_hw, struct clk_pll14xx, hw)
@@ -349,6 +362,42 @@ static int clk_pll1416x_set_rate(struct clk_hw *hw, unsigned long drate,
return 0;
}

+static void clk_pll1443x_enable_ssc(struct clk_hw *hw, unsigned long parent_rate,
+ unsigned int pdiv, unsigned int mdiv)
+{
+ struct clk_pll14xx *pll = to_clk_pll14xx(hw);
+ struct clk_spread_spectrum *conf = &pll->ssc_conf;
+ u32 sscg_ctrl, mfr, mrr, mod_type;
+
+ sscg_ctrl = readl_relaxed(pll->base + SSCG_CTRL);
+ sscg_ctrl &=
+ ~(SSCG_ENABLE | MFREQ_CTL_MASK | MRAT_CTL_MASK | SEL_PF_MASK);
+
+ mfr = parent_rate / (conf->modfreq * pdiv * (1 << 5));
+ mrr = ((conf->spreaddepth / 100) * mdiv * (1 << 6)) / (100 * mfr);
+
+ switch (conf->method) {
+ case CLK_SSC_CENTER_SPREAD:
+ mod_type = IMX_PLL14XX_SSC_CENTER_SPREAD;
+ break;
+ case CLK_SSC_UP_SPREAD:
+ mod_type = IMX_PLL14XX_SSC_UP_SPREAD;
+ break;
+ case CLK_SSC_DOWN_SPREAD:
+ mod_type = IMX_PLL14XX_SSC_DOWN_SPREAD;
+ break;
+ default:
+ mod_type = IMX_PLL14XX_SSC_DOWN_SPREAD;
+ break;
+ }
+
+ sscg_ctrl |= SSCG_ENABLE | FIELD_PREP(MFREQ_CTL_MASK, mfr) |
+ FIELD_PREP(MRAT_CTL_MASK, mrr) |
+ FIELD_PREP(SEL_PF_MASK, mod_type);
+
+ writel_relaxed(sscg_ctrl, pll->base + SSCG_CTRL);
+}
+
static int clk_pll1443x_set_rate(struct clk_hw *hw, unsigned long drate,
unsigned long prate)
{
@@ -370,6 +419,9 @@ static int clk_pll1443x_set_rate(struct clk_hw *hw, unsigned long drate,
writel_relaxed(FIELD_PREP(KDIV_MASK, rate.kdiv),
pll->base + DIV_CTL1);

+ if (pll->ssc_conf.enable)
+ clk_pll1443x_enable_ssc(hw, prate, rate.pdiv, rate.mdiv);
+
return 0;
}

@@ -410,6 +462,9 @@ static int clk_pll1443x_set_rate(struct clk_hw *hw, unsigned long drate,
gnrl_ctl &= ~BYPASS_MASK;
writel_relaxed(gnrl_ctl, pll->base + GNRL_CTL);

+ if (pll->ssc_conf.enable)
+ clk_pll1443x_enable_ssc(hw, prate, rate.pdiv, rate.mdiv);
+
return 0;
}

@@ -465,6 +520,16 @@ static void clk_pll14xx_unprepare(struct clk_hw *hw)
writel_relaxed(val, pll->base + GNRL_CTL);
}

+static int clk_pll1443x_set_spread_spectrum(struct clk_hw *hw,
+ struct clk_spread_spectrum *clk_ss)
+{
+ struct clk_pll14xx *pll = to_clk_pll14xx(hw);
+
+ memcpy(&pll->ssc_conf, clk_ss, sizeof(pll->ssc_conf));
+
+ return 0;
+}
+
static const struct clk_ops clk_pll1416x_ops = {
.prepare = clk_pll14xx_prepare,
.unprepare = clk_pll14xx_unprepare,
@@ -485,6 +550,7 @@ static const struct clk_ops clk_pll1443x_ops = {
.recalc_rate = clk_pll14xx_recalc_rate,
.round_rate = clk_pll1443x_round_rate,
.set_rate = clk_pll1443x_set_rate,
+ .set_spread_spectrum = clk_pll1443x_set_spread_spectrum,
};

struct clk_hw *imx_dev_clk_hw_pll14xx(struct device *dev, const char *name,

--
2.37.1