SPEAr: clk: Add VCO-PLL Synthesizer clock

All SPEAr SoC's contain PLLs. Their Fout is derived based on following equations

- In normal mode
  vco = (2 * M[15:8] * Fin)/N

- In Dithered mode
  vco = (2 * M[15:0] * Fin)/(256 * N)

pll_rate = vco/2^p

vco and pll are very closely bound to each other,
"vco needs to program: mode, m & n" and "pll needs to program p",
both share common enable/disable logic and registers.

This patch adds in support for this type of clock.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/Makefile

@@ -2,3 +2,6 @@
 obj-$(CONFIG_CLKDEV_LOOKUP)	+= clkdev.o
 obj-$(CONFIG_COMMON_CLK)	+= clk.o clk-fixed-rate.o clk-gate.o \
 				   clk-mux.o clk-divider.o clk-fixed-factor.o
+
+# SoCs specific
+obj-$(CONFIG_PLAT_SPEAR)	+= spear/

drivers/clk/spear/Makefile

+#
+# SPEAr Clock specific Makefile
+#
+
+obj-y	+= clk.o clk-vco-pll.o

drivers/clk/spear/clk-vco-pll.c

+/*
+ * Copyright (C) 2012 ST Microelectronics
+ * Viresh Kumar <viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * VCO-PLL clock implementation
+ */
+
+#define pr_fmt(fmt) "clk-vco-pll: " fmt
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include "clk.h"
+
+/*
+ * DOC: VCO-PLL clock
+ *
+ * VCO and PLL rate are derived from following equations:
+ *
+ * In normal mode
+ * vco = (2 * M[15:8] * Fin)/N
+ *
+ * In Dithered mode
+ * vco = (2 * M[15:0] * Fin)/(256 * N)
+ *
+ * pll_rate = pll/2^p
+ *
+ * vco and pll are very closely bound to each other, "vco needs to program:
+ * mode, m & n" and "pll needs to program p", both share common enable/disable
+ * logic.
+ *
+ * clk_register_vco_pll() registers instances of both vco & pll.
+ * CLK_SET_RATE_PARENT flag is forced for pll, as it will always pass its
+ * set_rate to vco. A single rate table exists for both the clocks, which
+ * configures m, n and p.
+ */
+
+/* PLL_CTR register masks */
+#define PLL_MODE_NORMAL		0
+#define PLL_MODE_FRACTION	1
+#define PLL_MODE_DITH_DSM	2
+#define PLL_MODE_DITH_SSM	3
+#define PLL_MODE_MASK		3
+#define PLL_MODE_SHIFT		3
+#define PLL_ENABLE		2
+
+#define PLL_LOCK_SHIFT		0
+#define PLL_LOCK_MASK		1
+
+/* PLL FRQ register masks */
+#define PLL_NORM_FDBK_M_MASK	0xFF
+#define PLL_NORM_FDBK_M_SHIFT	24
+#define PLL_DITH_FDBK_M_MASK	0xFFFF
+#define PLL_DITH_FDBK_M_SHIFT	16
+#define PLL_DIV_P_MASK		0x7
+#define PLL_DIV_P_SHIFT		8
+#define PLL_DIV_N_MASK		0xFF
+#define PLL_DIV_N_SHIFT		0
+
+#define to_clk_vco(_hw) container_of(_hw, struct clk_vco, hw)
+#define to_clk_pll(_hw) container_of(_hw, struct clk_pll, hw)
+
+/* Calculates pll clk rate for specific value of mode, m, n and p */
+static unsigned long pll_calc_rate(struct pll_rate_tbl *rtbl,
+		unsigned long prate, int index, unsigned long *pll_rate)
+{
+	unsigned long rate = prate;
+	unsigned int mode;
+
+	mode = rtbl[index].mode ? 256 : 1;
+	rate = (((2 * rate / 10000) * rtbl[index].m) / (mode * rtbl[index].n));
+
+	if (pll_rate)
+		*pll_rate = (rate / (1 << rtbl[index].p)) * 10000;
+
+	return rate * 10000;
+}
+
+static long clk_pll_round_rate_index(struct clk_hw *hw, unsigned long drate,
+				unsigned long *prate, int *index)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	unsigned long prev_rate, vco_prev_rate, rate = 0;
+	unsigned long vco_parent_rate =
+		__clk_get_rate(__clk_get_parent(__clk_get_parent(hw->clk)));
+
+	if (!prate) {
+		pr_err("%s: prate is must for pll clk\n", __func__);
+		return -EINVAL;
+	}
+
+	for (*index = 0; *index < pll->vco->rtbl_cnt; (*index)++) {
+		prev_rate = rate;
+		vco_prev_rate = *prate;
+		*prate = pll_calc_rate(pll->vco->rtbl, vco_parent_rate, *index,
+				&rate);
+		if (drate < rate) {
+			/* previous clock was best */
+			if (*index) {
+				rate = prev_rate;
+				*prate = vco_prev_rate;
+				(*index)--;
+			}
+			break;
+		}
+	}
+
+	return rate;
+}
+
+static long clk_pll_round_rate(struct clk_hw *hw, unsigned long drate,
+				unsigned long *prate)
+{
+	int unused;
+
+	return clk_pll_round_rate_index(hw, drate, prate, &unused);
+}
+
+static unsigned long clk_pll_recalc_rate(struct clk_hw *hw, unsigned long
+		parent_rate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	unsigned long flags = 0;
+	unsigned int p;
+
+	if (pll->vco->lock)
+		spin_lock_irqsave(pll->vco->lock, flags);
+
+	p = readl_relaxed(pll->vco->cfg_reg);
+
+	if (pll->vco->lock)
+		spin_unlock_irqrestore(pll->vco->lock, flags);
+
+	p = (p >> PLL_DIV_P_SHIFT) & PLL_DIV_P_MASK;
+
+	return parent_rate / (1 << p);
+}
+
+static int clk_pll_set_rate(struct clk_hw *hw, unsigned long drate,
+				unsigned long prate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	struct pll_rate_tbl *rtbl = pll->vco->rtbl;
+	unsigned long flags = 0, val;
+	int i;
+
+	clk_pll_round_rate_index(hw, drate, NULL, &i);
+
+	if (pll->vco->lock)
+		spin_lock_irqsave(pll->vco->lock, flags);
+
+	val = readl_relaxed(pll->vco->cfg_reg);
+	val &= ~(PLL_DIV_P_MASK << PLL_DIV_P_SHIFT);
+	val |= (rtbl[i].p & PLL_DIV_P_MASK) << PLL_DIV_P_SHIFT;
+	writel_relaxed(val, pll->vco->cfg_reg);
+
+	if (pll->vco->lock)
+		spin_unlock_irqrestore(pll->vco->lock, flags);
+
+	return 0;
+}
+
+static struct clk_ops clk_pll_ops = {
+	.recalc_rate = clk_pll_recalc_rate,
+	.round_rate = clk_pll_round_rate,
+	.set_rate = clk_pll_set_rate,
+};
+
+static inline unsigned long vco_calc_rate(struct clk_hw *hw,
+		unsigned long prate, int index)
+{
+	struct clk_vco *vco = to_clk_vco(hw);
+
+	return pll_calc_rate(vco->rtbl, prate, index, NULL);
+}
+
+static long clk_vco_round_rate(struct clk_hw *hw, unsigned long drate,
+		unsigned long *prate)
+{
+	struct clk_vco *vco = to_clk_vco(hw);
+	int unused;
+
+	return clk_round_rate_index(hw, drate, *prate, vco_calc_rate,
+			vco->rtbl_cnt, &unused);
+}
+
+static unsigned long clk_vco_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct clk_vco *vco = to_clk_vco(hw);
+	unsigned long flags = 0;
+	unsigned int num = 2, den = 0, val, mode = 0;
+
+	if (vco->lock)
+		spin_lock_irqsave(vco->lock, flags);
+
+	mode = (readl_relaxed(vco->mode_reg) >> PLL_MODE_SHIFT) & PLL_MODE_MASK;
+
+	val = readl_relaxed(vco->cfg_reg);
+
+	if (vco->lock)
+		spin_unlock_irqrestore(vco->lock, flags);
+
+	den = (val >> PLL_DIV_N_SHIFT) & PLL_DIV_N_MASK;
+
+	/* calculate numerator & denominator */
+	if (!mode) {
+		/* Normal mode */
+		num *= (val >> PLL_NORM_FDBK_M_SHIFT) & PLL_NORM_FDBK_M_MASK;
+	} else {
+		/* Dithered mode */
+		num *= (val >> PLL_DITH_FDBK_M_SHIFT) & PLL_DITH_FDBK_M_MASK;
+		den *= 256;
+	}
+
+	if (!den) {
+		WARN(1, "%s: denominator can't be zero\n", __func__);
+		return 0;
+	}
+
+	return (((parent_rate / 10000) * num) / den) * 10000;
+}
+
+/* Configures new clock rate of vco */
+static int clk_vco_set_rate(struct clk_hw *hw, unsigned long drate,
+				unsigned long prate)
+{
+	struct clk_vco *vco = to_clk_vco(hw);
+	struct pll_rate_tbl *rtbl = vco->rtbl;
+	unsigned long flags = 0, val;
+	int i;
+
+	clk_round_rate_index(hw, drate, prate, vco_calc_rate, vco->rtbl_cnt,
+			&i);
+
+	if (vco->lock)
+		spin_lock_irqsave(vco->lock, flags);
+
+	val = readl_relaxed(vco->mode_reg);
+	val &= ~(PLL_MODE_MASK << PLL_MODE_SHIFT);
+	val |= (rtbl[i].mode & PLL_MODE_MASK) << PLL_MODE_SHIFT;
+	writel_relaxed(val, vco->mode_reg);
+
+	val = readl_relaxed(vco->cfg_reg);
+	val &= ~(PLL_DIV_N_MASK << PLL_DIV_N_SHIFT);
+	val |= (rtbl[i].n & PLL_DIV_N_MASK) << PLL_DIV_N_SHIFT;
+
+	val &= ~(PLL_DITH_FDBK_M_MASK << PLL_DITH_FDBK_M_SHIFT);
+	if (rtbl[i].mode)
+		val |= (rtbl[i].m & PLL_DITH_FDBK_M_MASK) <<
+			PLL_DITH_FDBK_M_SHIFT;
+	else
+		val |= (rtbl[i].m & PLL_NORM_FDBK_M_MASK) <<
+			PLL_NORM_FDBK_M_SHIFT;
+
+	writel_relaxed(val, vco->cfg_reg);
+
+	if (vco->lock)
+		spin_unlock_irqrestore(vco->lock, flags);
+
+	return 0;
+}
+
+static struct clk_ops clk_vco_ops = {
+	.recalc_rate = clk_vco_recalc_rate,
+	.round_rate = clk_vco_round_rate,
+	.set_rate = clk_vco_set_rate,
+};
+
+struct clk *clk_register_vco_pll(const char *vco_name, const char *pll_name,
+		const char *vco_gate_name, const char *parent_name,
+		unsigned long flags, void __iomem *mode_reg, void __iomem
+		*cfg_reg, struct pll_rate_tbl *rtbl, u8 rtbl_cnt,
+		spinlock_t *lock, struct clk **pll_clk,
+		struct clk **vco_gate_clk)
+{
+	struct clk_vco *vco;
+	struct clk_pll *pll;
+	struct clk *vco_clk, *tpll_clk, *tvco_gate_clk;
+	struct clk_init_data vco_init, pll_init;
+	const char **vco_parent_name;
+
+	if (!vco_name || !pll_name || !parent_name || !mode_reg || !cfg_reg ||
+			!rtbl || !rtbl_cnt) {
+		pr_err("Invalid arguments passed");
+		return ERR_PTR(-EINVAL);
+	}
+
+	vco = kzalloc(sizeof(*vco), GFP_KERNEL);
+	if (!vco) {
+		pr_err("could not allocate vco clk\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+	if (!pll) {
+		pr_err("could not allocate pll clk\n");
+		goto free_vco;
+	}
+
+	/* struct clk_vco assignments */
+	vco->mode_reg = mode_reg;
+	vco->cfg_reg = cfg_reg;
+	vco->rtbl = rtbl;
+	vco->rtbl_cnt = rtbl_cnt;
+	vco->lock = lock;
+	vco->hw.init = &vco_init;
+
+	pll->vco = vco;
+	pll->hw.init = &pll_init;
+
+	if (vco_gate_name) {
+		tvco_gate_clk = clk_register_gate(NULL, vco_gate_name,
+				parent_name, 0, mode_reg, PLL_ENABLE, 0, lock);
+		if (IS_ERR_OR_NULL(tvco_gate_clk))
+			goto free_pll;
+
+		if (vco_gate_clk)
+			*vco_gate_clk = tvco_gate_clk;
+		vco_parent_name = &vco_gate_name;
+	} else {
+		vco_parent_name = &parent_name;
+	}
+
+	vco_init.name = vco_name;
+	vco_init.ops = &clk_vco_ops;
+	vco_init.flags = flags;
+	vco_init.parent_names = vco_parent_name;
+	vco_init.num_parents = 1;
+
+	pll_init.name = pll_name;
+	pll_init.ops = &clk_pll_ops;
+	pll_init.flags = CLK_SET_RATE_PARENT;
+	pll_init.parent_names = &vco_name;
+	pll_init.num_parents = 1;
+
+	vco_clk = clk_register(NULL, &vco->hw);
+	if (IS_ERR_OR_NULL(vco_clk))
+		goto free_pll;
+
+	tpll_clk = clk_register(NULL, &pll->hw);
+	if (IS_ERR_OR_NULL(tpll_clk))
+		goto free_pll;
+
+	if (pll_clk)
+		*pll_clk = tpll_clk;
+
+	return vco_clk;
+
+free_pll:
+	kfree(pll);
+free_vco:
+	kfree(vco);
+
+	pr_err("Failed to register vco pll clock\n");
+
+	return ERR_PTR(-ENOMEM);
+}

drivers/clk/spear/clk.c

+/*
+ * Copyright (C) 2012 ST Microelectronics
+ * Viresh Kumar <viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * SPEAr clk - Common routines
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/types.h>
+#include "clk.h"
+
+long clk_round_rate_index(struct clk_hw *hw, unsigned long drate,
+		unsigned long parent_rate, clk_calc_rate calc_rate, u8 rtbl_cnt,
+		int *index)
+{
+	unsigned long prev_rate, rate = 0;
+
+	for (*index = 0; *index < rtbl_cnt; (*index)++) {
+		prev_rate = rate;
+		rate = calc_rate(hw, parent_rate, *index);
+		if (drate < rate) {
+			/* previous clock was best */
+			if (*index) {
+				rate = prev_rate;
+				(*index)--;
+			}
+			break;
+		}
+	}
+
+	return rate;
+}

drivers/clk/spear/clk.h

+/*
+ * Clock framework definitions for SPEAr platform
+ *
+ * Copyright (C) 2012 ST Microelectronics
+ * Viresh Kumar <viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __SPEAR_CLK_H
+#define __SPEAR_CLK_H
+
+#include <linux/clk-provider.h>
+#include <linux/spinlock_types.h>
+#include <linux/types.h>
+
+/* VCO-PLL clk */
+struct pll_rate_tbl {
+	u8 mode;
+	u16 m;
+	u8 n;
+	u8 p;
+};
+
+struct clk_vco {
+	struct			clk_hw hw;
+	void __iomem		*mode_reg;
+	void __iomem		*cfg_reg;
+	struct pll_rate_tbl	*rtbl;
+	u8			rtbl_cnt;
+	spinlock_t		*lock;
+};
+
+struct clk_pll {
+	struct			clk_hw hw;
+	struct clk_vco		*vco;
+	const char		*parent[1];
+	spinlock_t		*lock;
+};
+
+typedef unsigned long (*clk_calc_rate)(struct clk_hw *hw, unsigned long prate,
+		int index);
+
+/* clk register routines */
+struct clk *clk_register_vco_pll(const char *vco_name, const char *pll_name,
+		const char *vco_gate_name, const char *parent_name,
+		unsigned long flags, void __iomem *mode_reg, void __iomem
+		*cfg_reg, struct pll_rate_tbl *rtbl, u8 rtbl_cnt,
+		spinlock_t *lock, struct clk **pll_clk,
+		struct clk **vco_gate_clk);
+
+long clk_round_rate_index(struct clk_hw *hw, unsigned long drate,
+		unsigned long parent_rate, clk_calc_rate calc_rate, u8 rtbl_cnt,
+		int *index);
+
+#endif /* __SPEAR_CLK_H */