[PATCH v3 2/4] clk: imx: add fractional PLL output clock

[Abel Vesa <abel.vesa@nxp.com>]

From: Lucas Stach <l.stach@pengutronix.de>

This is a new clock type introduced on i.MX8.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
---
 drivers/clk/imx/Makefile       |   1 +
 drivers/clk/imx/clk-frac-pll.c | 230 +++++++++++++++++++++++++++++++++++++++++
 drivers/clk/imx/clk.h          |   3 +
 3 files changed, 234 insertions(+)
 create mode 100644 drivers/clk/imx/clk-frac-pll.c

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index 8c3baa7..4893c1f 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -6,6 +6,7 @@ obj-y += \
 	clk-cpu.o \
 	clk-fixup-div.o \
 	clk-fixup-mux.o \
+	clk-frac-pll.o \
 	clk-gate-exclusive.o \
 	clk-gate2.o \
 	clk-pllv1.o \
diff --git a/drivers/clk/imx/clk-frac-pll.c b/drivers/clk/imx/clk-frac-pll.c
new file mode 100644
index 0000000..c80c6ed
--- /dev/null
+++ b/drivers/clk/imx/clk-frac-pll.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 NXP.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+#define PLL_CFG0		0x0
+#define PLL_CFG1		0x4
+
+#define PLL_LOCK_STATUS		BIT(31)
+#define PLL_PD			19
+#define PLL_PD_MASK		BIT(PLL_PD)
+#define PLL_BYPASS		14
+#define PLL_BYPASS_MASK		BIT(PLL_BYPASS)
+#define PLL_NEWDIV_VAL		BIT(12)
+#define PLL_NEWDIV_ACK		BIT(11)
+#define PLL_FRAC_DIV_MASK	0xffffff
+#define PLL_INT_DIV_MASK	0x7f
+#define PLL_OUTPUT_DIV_MASK	0x1f
+#define PLL_FRAC_DENOM		0x1000000
+
+struct clk_frac_pll {
+	struct clk_hw	hw;
+	void __iomem	*base;
+};
+
+#define to_clk_frac_pll(_hw) container_of(_hw, struct clk_frac_pll, hw)
+
+static int clk_wait_lock(struct clk_frac_pll *pll)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(10);
+	u32 val;
+
+	/* Wait for PLL to lock */
+	do {
+		if (readl_relaxed(pll->base) & PLL_LOCK_STATUS)
+			break;
+		if (time_after(jiffies, timeout))
+			break;
+	} while (1);
+
+	return readl_poll_timeout(pll->base, val,
+					val & PLL_LOCK_STATUS, 0, 1000);
+}
+
+static int clk_wait_ack(struct clk_frac_pll *pll)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(50);
+	u32 val;
+
+	/* return directly if the pll is in powerdown or in bypass */
+	if (readl_relaxed(pll->base) & (PLL_PD_MASK | PLL_BYPASS_MASK))
+		return 0;
+
+	/* Wait for the pll's divfi and divff to be reloaded */
+	do {
+		if (readl_relaxed(pll->base) & PLL_NEWDIV_ACK)
+			break;
+		if (time_after(jiffies, timeout))
+			break;
+	} while (1);
+
+	return readl_poll_timeout(pll->base, val,
+					val & PLL_NEWDIV_ACK, 0, 1000);
+}
+
+static int clk_pll_prepare(struct clk_hw *hw)
+{
+	struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+	u32 val;
+
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	val &= ~PLL_PD_MASK;
+	writel_relaxed(val, pll->base + PLL_CFG0);
+
+	return clk_wait_lock(pll);
+}
+
+static void clk_pll_unprepare(struct clk_hw *hw)
+{
+	struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+	u32 val;
+
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	val |= PLL_PD_MASK;
+	writel_relaxed(val, pll->base + PLL_CFG0);
+}
+
+static int clk_pll_is_prepared(struct clk_hw *hw)
+{
+	struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+	u32 val;
+
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	return (val & PLL_PD_MASK) ? 0 : 1;
+}
+
+static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
+					 unsigned long parent_rate)
+{
+	struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+	u32 val, divff, divfi, divq;
+	u64 temp64;
+
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	divq = ((val & PLL_OUTPUT_DIV_MASK) + 1) * 2;
+	val = readl_relaxed(pll->base + PLL_CFG1);
+	divff = (val >> 7) & PLL_FRAC_DIV_MASK;
+	divfi = (val & PLL_INT_DIV_MASK);
+
+	temp64 = (u64)parent_rate * 8;
+	temp64 *= divff;
+	do_div(temp64, PLL_FRAC_DENOM);
+	temp64 /= divq;
+
+	return parent_rate * 8 * (divfi + 1) / divq + (unsigned long)temp64;
+}
+
+static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long *prate)
+{
+	unsigned long parent_rate = *prate;
+	u32 divff, divfi;
+	u64 temp64;
+
+	parent_rate *= 8;
+	rate *= 2;
+	divfi = rate / parent_rate;
+	temp64 = (u64)(rate - divfi * parent_rate);
+	temp64 *= PLL_FRAC_DENOM;
+	do_div(temp64, parent_rate);
+	divff = temp64;
+
+	temp64 = (u64)parent_rate;
+	temp64 *= divff;
+	do_div(temp64, PLL_FRAC_DENOM);
+
+	return (parent_rate * divfi + (unsigned long)temp64) / 2;
+}
+
+/*
+ * To simplify the clock calculation, we can keep the 'PLL_OUTPUT_VAL' at zero
+ * (means the PLL output will be divided by 2). So the PLL output can use
+ * the below formula:
+ * pllout = parent_rate * 8 / 2 * DIVF_VAL;
+ * where DIVF_VAL = 1 + DIVFI + DIVFF / 2^24.
+ */
+static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+			    unsigned long parent_rate)
+{
+	struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+	u32 val, divfi, divff;
+	u64 temp64;
+	int ret;
+
+	parent_rate *= 8;
+	rate *= 2;
+	divfi = rate / parent_rate;
+	temp64 = (u64) (rate - divfi * parent_rate);
+	temp64 *= PLL_FRAC_DENOM;
+	do_div(temp64, parent_rate);
+	divff = temp64;
+
+	val = readl_relaxed(pll->base + PLL_CFG1);
+	val &= ~((PLL_FRAC_DIV_MASK << 7) | (PLL_INT_DIV_MASK));
+	val |= ((divff << 7) | (divfi - 1));
+	writel_relaxed(val, pll->base + PLL_CFG1);
+
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	val &= ~0x1f;
+	writel_relaxed(val, pll->base + PLL_CFG0);
+
+	/* Set the NEV_DIV_VAL to reload the DIVFI and DIVFF */
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	val |= PLL_NEWDIV_VAL;
+	writel_relaxed(val, pll->base + PLL_CFG0);
+
+	ret = clk_wait_ack(pll);
+
+	/* clear the NEV_DIV_VAL */
+	val = readl_relaxed(pll->base + PLL_CFG0);
+	val &= ~PLL_NEWDIV_VAL;
+	writel_relaxed(val, pll->base + PLL_CFG0);
+
+	return ret;
+}
+
+static const struct clk_ops clk_frac_pll_ops = {
+	.prepare	= clk_pll_prepare,
+	.unprepare	= clk_pll_unprepare,
+	.is_prepared	= clk_pll_is_prepared,
+	.recalc_rate	= clk_pll_recalc_rate,
+	.round_rate	= clk_pll_round_rate,
+	.set_rate	= clk_pll_set_rate,
+};
+
+struct clk *imx_clk_frac_pll(const char *name, const char *parent_name,
+			     void __iomem *base)
+{
+	struct clk_init_data init;
+	struct clk_frac_pll *pll;
+	struct clk *clk;
+
+	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+	if (!pll)
+		return ERR_PTR(-ENOMEM);
+
+	pll->base = base;
+	init.name = name;
+	init.ops = &clk_frac_pll_ops;
+	init.flags = 0;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	pll->hw.init = &init;
+
+	clk = clk_register(NULL, &pll->hw);
+	if (IS_ERR(clk))
+		kfree(pll);
+
+	return clk;
+}
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 8076ec0..13daf1c 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -27,6 +27,9 @@ struct clk *imx_clk_pllv1(enum imx_pllv1_type type, const char *name,
 struct clk *imx_clk_pllv2(const char *name, const char *parent,
 		void __iomem *base);
 
+struct clk *imx_clk_frac_pll(const char *name, const char *parent_name,
+			     void __iomem *base);
+
 enum imx_pllv3_type {
 	IMX_PLLV3_GENERIC,
 	IMX_PLLV3_SYS,
-- 
2.7.4