[PATCH 2/6] clk: imx: pll14xx: support spread spectrum clock generation

[Dario Binacchi <dario.binacchi@amarulasolutions.com>]

This patch adds support for spread spectrum clock (SSC) generation for
the pll14xxx. The addition of the "imx_clk_hw_pll14xx_ssc" macro has
minimized the number of changes required to avoid compilation errors
following the addition of the SSC setup parameter to the
"imx_dev_clk_hw_pll14xx" macro used in the files clk-imx8m{m,n,p}.c.
The change to the clk-imx8mp-audiomix.c file prevents the patch from
causing a compilation error.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 drivers/clk/imx/clk-imx8mp-audiomix.c |   2 +-
 drivers/clk/imx/clk-pll14xx.c         | 102 +++++++++++++++++++++++++-
 drivers/clk/imx/clk.h                 |  24 +++++-
 3 files changed, 124 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/imx/clk-imx8mp-audiomix.c b/drivers/clk/imx/clk-imx8mp-audiomix.c
index b2cb157703c5..bfcf2975c217 100644
--- a/drivers/clk/imx/clk-imx8mp-audiomix.c
+++ b/drivers/clk/imx/clk-imx8mp-audiomix.c
@@ -365,7 +365,7 @@ static int clk_imx8mp_audiomix_probe(struct platform_device *pdev)
 	clk_hw_data->hws[IMX8MP_CLK_AUDIOMIX_SAI_PLL_REF_SEL] = hw;
 
 	hw = imx_dev_clk_hw_pll14xx(dev, "sai_pll", "sai_pll_ref_sel",
-				    base + 0x400, &imx_1443x_pll);
+				    base + 0x400, &imx_1443x_pll, NULL);
 	if (IS_ERR(hw)) {
 		ret = PTR_ERR(hw);
 		goto err_clk_register;
diff --git a/drivers/clk/imx/clk-pll14xx.c b/drivers/clk/imx/clk-pll14xx.c
index d63564dbb12c..76014e243a57 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)
@@ -31,6 +33,10 @@
 #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
 
@@ -40,6 +46,7 @@ struct clk_pll14xx {
 	enum imx_pll14xx_type		type;
 	const struct imx_pll14xx_rate_table *rate_table;
 	int rate_count;
+	struct imx_pll14xx_ssc		ssc;
 };
 
 #define to_clk_pll14xx(_hw) container_of(_hw, struct clk_pll14xx, hw)
@@ -347,6 +354,27 @@ static int clk_pll1416x_set_rate(struct clk_hw *hw, unsigned long drate,
 	return 0;
 }
 
+static void clk_pll1443x_set_sscg(struct clk_hw *hw, unsigned long parent_rate,
+				  unsigned int pdiv, unsigned int mdiv)
+{
+	struct clk_pll14xx *pll = to_clk_pll14xx(hw);
+	struct imx_pll14xx_ssc *ssc = &pll->ssc;
+	u32 sscg_ctrl = readl_relaxed(pll->base + SSCG_CTRL);
+
+	sscg_ctrl &=
+		~(SSCG_ENABLE | MFREQ_CTL_MASK | MRAT_CTL_MASK | SEL_PF_MASK);
+	if (ssc->enable) {
+		u32 mfr = parent_rate / (ssc->mod_freq * pdiv * (1 << 5));
+		u32 mrr = (ssc->mod_rate * mdiv * (1 << 6)) / (100 * mfr);
+
+		sscg_ctrl |= SSCG_ENABLE | FIELD_PREP(MFREQ_CTL_MASK, mfr) |
+			     FIELD_PREP(MRAT_CTL_MASK, mrr) |
+			     FIELD_PREP(SEL_PF_MASK, ssc->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)
 {
@@ -368,6 +396,9 @@ 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.enable)
+			clk_pll1443x_set_sscg(hw, prate, rate.pdiv, rate.mdiv);
+
 		return 0;
 	}
 
@@ -408,6 +439,9 @@ 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.enable)
+		clk_pll1443x_set_sscg(hw, prate, rate.pdiv, rate.mdiv);
+
 	return 0;
 }
 
@@ -487,7 +521,8 @@ static const struct clk_ops clk_pll1443x_ops = {
 
 struct clk_hw *imx_dev_clk_hw_pll14xx(struct device *dev, const char *name,
 				const char *parent_name, void __iomem *base,
-				const struct imx_pll14xx_clk *pll_clk)
+				const struct imx_pll14xx_clk *pll_clk,
+				const struct imx_pll14xx_ssc *ssc)
 {
 	struct clk_pll14xx *pll;
 	struct clk_hw *hw;
@@ -525,6 +560,8 @@ struct clk_hw *imx_dev_clk_hw_pll14xx(struct device *dev, const char *name,
 	pll->type = pll_clk->type;
 	pll->rate_table = pll_clk->rate_table;
 	pll->rate_count = pll_clk->rate_count;
+	if (ssc)
+		memcpy(&pll->ssc, ssc, sizeof(pll->ssc));
 
 	val = readl_relaxed(pll->base + GNRL_CTL);
 	val &= ~BYPASS_MASK;
@@ -542,3 +579,66 @@ struct clk_hw *imx_dev_clk_hw_pll14xx(struct device *dev, const char *name,
 	return hw;
 }
 EXPORT_SYMBOL_GPL(imx_dev_clk_hw_pll14xx);
+
+static enum imx_pll14xx_ssc_mod_type clk_pll14xx_ssc_mode(const char *name,
+							  enum imx_pll14xx_ssc_mod_type def)
+{
+	int i;
+	struct {
+		const char *name;
+		enum imx_pll14xx_ssc_mod_type id;
+	} mod_methods[] = {
+		{ .name = "down-spread", .id = IMX_PLL14XX_SSC_DOWN_SPREAD },
+		{ .name = "up-spread", .id = IMX_PLL14XX_SSC_UP_SPREAD },
+		{ .name = "center-spread", .id = IMX_PLL14XX_SSC_CENTER_SPREAD }
+	};
+
+	for (i = 0; i < ARRAY_SIZE(mod_methods); i++) {
+		if (!strcmp(name, mod_methods[i].name))
+			return mod_methods[i].id;
+	}
+
+	return def;
+}
+
+void imx_clk_pll14xx_get_ssc_conf(struct device_node *np, int pll_id,
+				  struct imx_pll14xx_ssc *ssc)
+{
+	int i, ret, offset, num_clks;
+	u32 clk_id, clk_cell_size;
+	const char *s;
+
+	if (!ssc)
+		return;
+
+	memset(ssc, 0, sizeof(*ssc));
+
+	num_clks = of_count_phandle_with_args(np, "fsl,ssc-clocks",
+					      "#clock-cells");
+	if (num_clks <= 0)
+		return;
+
+	ret = of_property_read_u32(np, "#clock-cells", &clk_cell_size);
+	if (ret)
+		return;
+
+	for (i = 0; i < num_clks; i++) {
+		offset = i * clk_cell_size + 1;
+		of_property_read_u32_index(np, "fsl,ssc-clocks", offset,
+					   &clk_id);
+		if (clk_id != pll_id)
+			continue;
+
+		of_property_read_u32_index(np, "fsl,ssc-modfreq-hz", i,
+					   &ssc->mod_freq);
+		of_property_read_u32_index(np, "fsl,ssc-modrate-percent", i,
+					   &ssc->mod_rate);
+		if (!of_property_read_string(np, "fsl,ssc-modmethod", &s))
+			ssc->mod_type = clk_pll14xx_ssc_mode(
+				s, IMX_PLL14XX_SSC_DOWN_SPREAD);
+
+		ssc->enable = true;
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(imx_clk_pll14xx_get_ssc_conf);
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index aa5202f284f3..8cbc75480569 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -62,6 +62,19 @@ struct imx_pll14xx_rate_table {
 	unsigned int kdiv;
 };
 
+enum imx_pll14xx_ssc_mod_type {
+	IMX_PLL14XX_SSC_DOWN_SPREAD,
+	IMX_PLL14XX_SSC_UP_SPREAD,
+	IMX_PLL14XX_SSC_CENTER_SPREAD,
+};
+
+struct imx_pll14xx_ssc {
+	bool enable;
+	unsigned int mod_freq;
+	unsigned int mod_rate;
+	enum imx_pll14xx_ssc_mod_type mod_type;
+};
+
 struct imx_pll14xx_clk {
 	enum imx_pll14xx_type type;
 	const struct imx_pll14xx_rate_table *rate_table;
@@ -222,11 +235,18 @@ extern struct imx_fracn_gppll_clk imx_fracn_gppll_integer;
 	__imx_clk_hw_divider(name, parent, reg, shift, width, flags)
 
 #define imx_clk_hw_pll14xx(name, parent_name, base, pll_clk) \
-	imx_dev_clk_hw_pll14xx(NULL, name, parent_name, base, pll_clk)
+	imx_dev_clk_hw_pll14xx(NULL, name, parent_name, base, pll_clk, NULL)
+
+#define imx_clk_hw_pll14xx_ssc(name, parent_name, base, pll_clk, ssc)	\
+	imx_dev_clk_hw_pll14xx(NULL, name, parent_name, base, pll_clk, ssc)
 
 struct clk_hw *imx_dev_clk_hw_pll14xx(struct device *dev, const char *name,
 				const char *parent_name, void __iomem *base,
-				const struct imx_pll14xx_clk *pll_clk);
+				const struct imx_pll14xx_clk *pll_clk,
+				const struct imx_pll14xx_ssc *ssc);
+
+void imx_clk_pll14xx_get_ssc_conf(struct device_node *np, int pll_id,
+				  struct imx_pll14xx_ssc *ssc);
 
 struct clk_hw *imx_clk_hw_pllv1(enum imx_pllv1_type type, const char *name,
 		const char *parent, void __iomem *base);
-- 
2.43.0