[PATCH 3/4] clk: imx: support fracn gppll

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

This PLL module is a Fractional-N synthesizer,
supporting 30-bit numerator and denominator. Numerator is a signed
number. It has feature to adjust fractional portion of feedback
divider dynamically. This fracn gppll is used in i.MX93.

Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 drivers/clk/imx/Makefile          |   1 +
 drivers/clk/imx/clk-fracn-gppll.c | 327 ++++++++++++++++++++++++++++++
 drivers/clk/imx/clk.h             |  21 ++
 3 files changed, 349 insertions(+)
 create mode 100644 drivers/clk/imx/clk-fracn-gppll.c

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index 15549a1c332f..717a33c7ed50 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -5,6 +5,7 @@ mxc-clk-objs += clk-busy.o
 mxc-clk-objs += clk-composite-7ulp.o
 mxc-clk-objs += clk-composite-8m.o
 mxc-clk-objs += clk-composite-93.o
+mxc-clk-objs += clk-fracn-gppll.o
 mxc-clk-objs += clk-cpu.o
 mxc-clk-objs += clk-divider-gate.o
 mxc-clk-objs += clk-fixup-div.o
diff --git a/drivers/clk/imx/clk-fracn-gppll.c b/drivers/clk/imx/clk-fracn-gppll.c
new file mode 100644
index 000000000000..a4512b216ad5
--- /dev/null
+++ b/drivers/clk/imx/clk-fracn-gppll.c
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2021 NXP
+ */
+
+#include <linux/bits.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+
+#include "clk.h"
+
+#define PLL_CTRL		0x0
+#define CLKMUX_BYPASS		BIT(2)
+#define CLKMUX_EN		BIT(1)
+#define POWERUP_MASK		BIT(0)
+
+#define PLL_ANA_PRG		0x10
+#define PLL_SPREAD_SPECTRUM	0x30
+
+#define PLL_NUMERATOR		0x40
+#define PLL_MFN_MASK		GENMASK(31, 2)
+#define PLL_MFN_SHIFT		2
+
+#define PLL_DENOMINATOR		0x50
+#define PLL_MFD_MASK		GENMASK(29, 0)
+
+#define PLL_DIV			0x60
+#define PLL_MFI_MASK		GENMASK(24, 16)
+#define PLL_MFI_SHIFT		16
+#define PLL_RDIV_MASK		GENMASK(15, 13)
+#define PLL_RDIV_SHIFT		13
+#define PLL_ODIV_MASK		GENMASK(7, 0)
+
+#define PLL_DFS_CTRL(x)		(0x70 + (x) * 0x10)
+
+#define PLL_STATUS		0xF0
+#define LOCK_STATUS		BIT(0)
+
+#define DFS_STATUS		0xF4
+
+#define LOCK_TIMEOUT_US		200
+
+#define PLL_FRACN_GP(_rate, _mfi, _mfn, _mfd, _rdiv, _odiv)	\
+	{							\
+		.rate	=	(_rate),			\
+		.mfi	=	(_mfi),				\
+		.mfn	=	(_mfn),				\
+		.mfd	=	(_mfd),				\
+		.rdiv	=	(_rdiv),			\
+		.odiv	=	(_odiv),			\
+	}
+
+struct clk_fracn_gppll {
+	struct clk_hw			hw;
+	void __iomem			*base;
+	const struct imx_fracn_gppll_rate_table *rate_table;
+	int rate_count;
+};
+
+#define to_clk_fracn_gppll(_hw) container_of(_hw, struct clk_fracn_gppll, hw)
+
+/*
+ * Fvco = 𝐹𝑟𝑒𝑓∙(𝑀𝐹𝐼+𝑀𝐹𝑁/𝑀𝐹𝐷)
+ * Fout = Fvco / (rdiv * odiv)
+ */
+static const struct imx_fracn_gppll_rate_table fracn_tbl[] = {
+	PLL_FRACN_GP(650000000U, 81, 0, 0, 0, 3),
+	PLL_FRACN_GP(594000000U, 198, 0, 0, 0, 8),
+	PLL_FRACN_GP(560000000U, 70, 0, 0, 0, 3),
+	PLL_FRACN_GP(400000000U, 50, 0, 0, 0, 3),
+	PLL_FRACN_GP(393216000U, 81, 92, 100, 0, 5)
+};
+
+struct imx_fracn_gppll_clk imx_fracn_gppll = {
+	.rate_table = fracn_tbl,
+	.rate_count = ARRAY_SIZE(fracn_tbl),
+};
+EXPORT_SYMBOL_GPL(imx_fracn_gppll);
+
+static const struct imx_fracn_gppll_rate_table *
+imx_get_pll_settings(struct clk_fracn_gppll *pll, unsigned long rate)
+{
+	const struct imx_fracn_gppll_rate_table *rate_table = pll->rate_table;
+	int i;
+
+	for (i = 0; i < pll->rate_count; i++)
+		if (rate == rate_table[i].rate)
+			return &rate_table[i];
+
+	return NULL;
+}
+
+static long clk_fracn_gppll_round_rate(struct clk_hw *hw, unsigned long rate,
+				       unsigned long *prate)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	const struct imx_fracn_gppll_rate_table *rate_table = pll->rate_table;
+	int i;
+
+	/* Assumming rate_table is in descending order */
+	for (i = 0; i < pll->rate_count; i++)
+		if (rate >= rate_table[i].rate)
+			return rate_table[i].rate;
+
+	if (i == pll->rate_count)
+		pr_err("Not able to round rate for %s: %lu\n", clk_hw_get_name(hw), rate);
+
+	/* return minimum supported value */
+	return rate_table[i - 1].rate;
+}
+
+static unsigned long clk_fracn_gppll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	const struct imx_fracn_gppll_rate_table *rate_table = pll->rate_table;
+	u32 pll_numerator, pll_denominator, pll_div;
+	u32 mfi, mfn, mfd, rdiv, odiv;
+	u64 fvco = parent_rate;
+	long rate = 0;
+	int i;
+
+	pll_numerator = readl_relaxed(pll->base + PLL_NUMERATOR);
+	mfn = (pll_numerator & PLL_MFN_MASK) >> PLL_MFN_SHIFT;
+
+	pll_denominator = readl_relaxed(pll->base + PLL_DENOMINATOR);
+	mfd = pll_denominator & PLL_MFD_MASK;
+
+	pll_div = readl_relaxed(pll->base + PLL_DIV);
+	mfi = (pll_div & PLL_MFI_MASK) >> PLL_MFI_SHIFT;
+
+	rdiv = (pll_div & PLL_RDIV_MASK) >> PLL_RDIV_SHIFT;
+	rdiv = rdiv + 1;
+	odiv = pll_div & PLL_ODIV_MASK;
+	switch (odiv) {
+	case 0:
+		odiv = 2;
+		break;
+	case 1:
+		odiv = 3;
+		break;
+	default:
+		break;
+	}
+
+	/*
+	 * Sometimes, the recalculated rate has deviation due to
+	 * the frac part. So find the accurate pll rate from the table
+	 * first, if no match rate in the table, use the rate calculated
+	 * from the equation below.
+	 */
+	for (i = 0; i < pll->rate_count; i++) {
+		if (rate_table[i].mfn == mfn && rate_table[i].mfi == mfi &&
+		    rate_table[i].mfd == mfd && rate_table[i].rdiv == rdiv &&
+		    rate_table[i].odiv == odiv)
+			rate = rate_table[i].rate;
+	}
+
+	/* Fvco = 𝐹𝑟𝑒𝑓∙(𝑀𝐹𝐼+𝑀𝐹𝑁/𝑀𝐹𝐷) */
+	fvco = fvco * mfi + fvco * mfn / mfd;
+
+	do_div(fvco, rdiv * odiv);
+
+	return rate ? (unsigned long) rate : (unsigned long)fvco;
+}
+
+static int clk_fracn_gppll_wait_lock(struct clk_fracn_gppll *pll)
+{
+	u32 val;
+
+	return readl_poll_timeout(pll->base + PLL_STATUS, val,
+				  val & LOCK_STATUS, 0, LOCK_TIMEOUT_US);
+}
+
+static int clk_fracn_gppll_set_rate(struct clk_hw *hw, unsigned long drate,
+				    unsigned long prate)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	const struct imx_fracn_gppll_rate_table *rate;
+	u32 tmp, pll_div, ana_mfn;
+	int ret;
+
+	rate = imx_get_pll_settings(pll, drate);
+	if (!rate) {
+		pr_err("%s: Invalid rate : %lu for pll clk %s\n", __func__,
+			drate, clk_hw_get_name(hw));
+		return -EINVAL;
+	}
+
+	/* Disable output */
+	tmp = readl_relaxed(pll->base + PLL_CTRL);
+	tmp &= ~CLKMUX_EN;
+	writel_relaxed(tmp, pll->base + PLL_CTRL);
+
+	/* Power Down */
+	tmp &= ~POWERUP_MASK;
+	writel_relaxed(tmp, pll->base + PLL_CTRL);
+
+	/* Disable BYPASS */
+	tmp &= ~CLKMUX_BYPASS;
+	writel_relaxed(tmp, pll->base + PLL_CTRL);
+
+	pll_div = (rate->rdiv << PLL_RDIV_SHIFT) | rate->odiv | (rate->mfi << PLL_MFI_SHIFT);
+	writel_relaxed(pll_div, pll->base + PLL_DIV);
+	writel_relaxed(rate->mfd, pll->base + PLL_DENOMINATOR);
+	writel_relaxed(rate->mfn << PLL_MFN_SHIFT, pll->base + PLL_NUMERATOR);
+
+	/* Wait for 5us according to fracn mode pll doc */
+	udelay(5);
+
+	/* Enable Powerup */
+	tmp |= POWERUP_MASK;
+	writel_relaxed(tmp, pll->base + PLL_CTRL);
+
+	/* Wait Lock*/
+	ret = clk_fracn_gppll_wait_lock(pll);
+	if (ret)
+		return ret;
+
+	/* Enable output */
+	tmp |= CLKMUX_EN;
+	writel_relaxed(tmp, pll->base + PLL_CTRL);
+
+	ana_mfn = (readl_relaxed(pll->base + PLL_STATUS) & PLL_MFN_MASK) >> PLL_MFN_SHIFT;
+
+	WARN(ana_mfn != rate->mfn, "ana_mfn != rate->mfn\n");
+
+	return 0;
+}
+
+static int clk_fracn_gppll_prepare(struct clk_hw *hw)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	u32 val;
+	int ret;
+
+	val = readl_relaxed(pll->base + PLL_CTRL);
+	if (val & POWERUP_MASK)
+		return 0;
+
+	val |= CLKMUX_BYPASS;
+	writel_relaxed(val, pll->base + PLL_CTRL);
+
+	val |= POWERUP_MASK;
+	writel_relaxed(val, pll->base + PLL_CTRL);
+
+	val |= CLKMUX_EN;
+	writel_relaxed(val, pll->base + PLL_CTRL);
+
+	ret = clk_fracn_gppll_wait_lock(pll);
+	if (ret)
+		return ret;
+
+	val &= ~CLKMUX_BYPASS;
+	writel_relaxed(val, pll->base + PLL_CTRL);
+
+	return 0;
+}
+
+static int clk_fracn_gppll_is_prepared(struct clk_hw *hw)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	u32 val;
+
+	val = readl_relaxed(pll->base + PLL_CTRL);
+
+	return (val & POWERUP_MASK) ? 1 : 0;
+}
+
+static void clk_fracn_gppll_unprepare(struct clk_hw *hw)
+{
+	struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw);
+	u32 val;
+
+	val = readl_relaxed(pll->base + PLL_CTRL);
+	val &= ~POWERUP_MASK;
+	writel_relaxed(val, pll->base + PLL_CTRL);
+}
+
+static const struct clk_ops clk_fracn_gppll_ops = {
+	.prepare	= clk_fracn_gppll_prepare,
+	.unprepare	= clk_fracn_gppll_unprepare,
+	.is_prepared	= clk_fracn_gppll_is_prepared,
+	.recalc_rate	= clk_fracn_gppll_recalc_rate,
+	.round_rate	= clk_fracn_gppll_round_rate,
+	.set_rate	= clk_fracn_gppll_set_rate,
+};
+
+struct clk_hw *imx_clk_fracn_gppll(const char *name, const char *parent_name, void __iomem *base,
+				   const struct imx_fracn_gppll_clk *pll_clk)
+{
+	struct clk_fracn_gppll *pll;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	int ret;
+
+	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+	if (!pll)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.flags = pll_clk->flags;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+	init.ops = &clk_fracn_gppll_ops;
+
+	pll->base = base;
+	pll->hw.init = &init;
+	pll->rate_table = pll_clk->rate_table;
+	pll->rate_count = pll_clk->rate_count;
+
+	hw = &pll->hw;
+
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		pr_err("%s: failed to register pll %s %d\n", __func__, name, ret);
+		kfree(pll);
+		return ERR_PTR(ret);
+	}
+
+	return hw;
+}
+EXPORT_SYMBOL_GPL(imx_clk_fracn_gppll);
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 63eb7c53b123..a7cbbcd1a3f4 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -72,6 +72,27 @@ extern struct imx_pll14xx_clk imx_1416x_pll;
 extern struct imx_pll14xx_clk imx_1443x_pll;
 extern struct imx_pll14xx_clk imx_1443x_dram_pll;
 
+/* NOTE: Rate table should be kept sorted in descending order. */
+struct imx_fracn_gppll_rate_table {
+	unsigned int rate;
+	unsigned int mfi;
+	unsigned int mfn;
+	unsigned int mfd;
+	unsigned int rdiv;
+	unsigned int odiv;
+};
+
+struct imx_fracn_gppll_clk {
+	const struct imx_fracn_gppll_rate_table *rate_table;
+	int rate_count;
+	int flags;
+};
+
+struct clk_hw *imx_clk_fracn_gppll(const char *name, const char *parent_name, void __iomem *base,
+				   const struct imx_fracn_gppll_clk *pll_clk);
+
+extern struct imx_fracn_gppll_clk imx_fracn_gppll;
+
 #define imx_clk_cpu(name, parent_name, div, mux, pll, step) \
 	to_clk(imx_clk_hw_cpu(name, parent_name, div, mux, pll, step))
 
-- 
2.25.1