[RFC/PATCH 03/12] clk: qcom: Add support for muxes, dividers, and mux dividers

[Stephen Boyd]

The Krait CPU clocks are made up of muxes and dividers with a
handful of sources. Add a set of clk_ops that allow us to
configure these clocks so we can support CPU frequency scaling on
Krait CPUs.

Based on code originally written by Saravana Kannan.

Cc: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
---
 drivers/clk/qcom/Makefile           |   1 +
 drivers/clk/qcom/clk-generic.c      | 405 ++++++++++++++++++++++++++++++++++++
 include/linux/clk/msm-clk-generic.h | 208 ++++++++++++++++++
 3 files changed, 614 insertions(+)
 create mode 100644 drivers/clk/qcom/clk-generic.c
 create mode 100644 include/linux/clk/msm-clk-generic.h

diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index 689e05bf4f95..8684ff004be6 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -6,6 +6,7 @@ clk-qcom-y += clk-pll.o
 clk-qcom-y += clk-rcg.o
 clk-qcom-y += clk-rcg2.o
 clk-qcom-y += clk-branch.o
+clk-qcom-y += clk-generic.o
 clk-qcom-y += reset.o
 
 obj-$(CONFIG_MSM_GCC_8660) += gcc-msm8660.o
diff --git a/drivers/clk/qcom/clk-generic.c b/drivers/clk/qcom/clk-generic.c
new file mode 100644
index 000000000000..a0d778ba7394
--- /dev/null
+++ b/drivers/clk/qcom/clk-generic.c
@@ -0,0 +1,405 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/clk-provider.h>
+#include <linux/clk/msm-clk-generic.h>
+
+
+/* ==================== Mux clock ==================== */
+
+static int mux_set_parent(struct clk_hw *hw, u8 sel)
+{
+	struct mux_clk *mux = to_mux_clk(hw);
+
+	if (mux->parent_map)
+		sel = mux->parent_map[sel];
+
+	return mux->ops->set_mux_sel(mux, sel);
+}
+
+static u8 mux_get_parent(struct clk_hw *hw)
+{
+	struct mux_clk *mux = to_mux_clk(hw);
+	int num_parents = __clk_get_num_parents(hw->clk);
+	int i;
+	u8 sel;
+
+	sel = mux->ops->get_mux_sel(mux);
+	if (mux->parent_map) {
+		for (i = 0; i < num_parents; i++)
+			if (sel == mux->parent_map[i])
+				return i;
+		WARN(1, "Can't find parent\n");
+		return -EINVAL;
+	}
+
+	return sel;
+}
+
+static int mux_enable(struct clk_hw *hw)
+{
+	struct mux_clk *mux = to_mux_clk(hw);
+	if (mux->ops->enable)
+		return mux->ops->enable(mux);
+	return 0;
+}
+
+static void mux_disable(struct clk_hw *hw)
+{
+	struct mux_clk *mux = to_mux_clk(hw);
+	if (mux->ops->disable)
+		return mux->ops->disable(mux);
+}
+
+static struct clk *mux_get_safe_parent(struct clk_hw *hw)
+{
+	int i;
+	struct mux_clk *mux = to_mux_clk(hw);
+	int num_parents = __clk_get_num_parents(hw->clk);
+
+	if (!mux->has_safe_parent)
+		return NULL;
+
+	i = mux->safe_sel;
+	if (mux->parent_map)
+		for (i = 0; i < num_parents; i++)
+			if (mux->safe_sel == mux->parent_map[i])
+				break;
+
+	return clk_get_parent_by_index(hw->clk, i);
+}
+
+const struct clk_ops clk_ops_gen_mux = {
+	.enable = mux_enable,
+	.disable = mux_disable,
+	.set_parent = mux_set_parent,
+	.get_parent = mux_get_parent,
+	.determine_rate = __clk_mux_determine_rate,
+	.get_safe_parent = mux_get_safe_parent,
+};
+EXPORT_SYMBOL_GPL(clk_ops_gen_mux);
+
+/* ==================== Divider clock ==================== */
+
+static long __div_round_rate(struct div_data *data, unsigned long rate,
+	struct clk *parent, unsigned int *best_div, unsigned long *best_prate,
+	bool set_parent)
+{
+	unsigned int div, min_div, max_div, _best_div = 1;
+	unsigned long prate, _best_prate = 0, rrate = 0, req_prate, actual_rate;
+	unsigned int numer;
+
+	rate = max(rate, 1UL);
+
+	min_div = max(data->min_div, 1U);
+	max_div = min(data->max_div, (unsigned int) (ULONG_MAX / rate));
+
+	/*
+	 * div values are doubled for half dividers.
+	 * Adjust for that by picking a numer of 2.
+	 */
+	numer = data->is_half_divider ? 2 : 1;
+
+	if (!set_parent) {
+		prate = *best_prate * numer;
+		div = DIV_ROUND_UP(prate, rate);
+		div = clamp(1U, div, max_div);
+		if (best_div)
+			*best_div = div;
+		return mult_frac(*best_prate, numer, div);
+	}
+
+	for (div = min_div; div <= max_div; div++) {
+		req_prate = mult_frac(rate, div, numer);
+		prate = __clk_round_rate(parent, req_prate);
+		if (IS_ERR_VALUE(prate))
+			break;
+
+		actual_rate = mult_frac(prate, numer, div);
+		if (is_better_rate(rate, rrate, actual_rate)) {
+			rrate = actual_rate;
+			_best_div = div;
+			_best_prate = prate;
+		}
+
+		/*
+		 * Trying higher dividers is only going to ask the parent for
+		 * a higher rate. If it can't even output a rate higher than
+		 * the one we request for this divider, the parent is not
+		 * going to be able to output an even higher rate required
+		 * for a higher divider. So, stop trying higher dividers.
+		 */
+		if (actual_rate < rate)
+			break;
+
+		if (rrate <= rate)
+			break;
+	}
+
+	if (!rrate)
+		return -EINVAL;
+	if (best_div)
+		*best_div = _best_div;
+	if (best_prate)
+		*best_prate = _best_prate;
+
+	return rrate;
+}
+
+static long div_round_rate(struct clk_hw *hw, unsigned long rate,
+			   unsigned long *parent_rate)
+{
+	struct div_clk *d = to_div_clk(hw);
+	bool set_parent = __clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT;
+
+	return __div_round_rate(&d->data, rate, __clk_get_parent(hw->clk),
+				NULL, parent_rate, set_parent);
+}
+
+static int div_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long
+			parent_rate)
+{
+	struct div_clk *d = to_div_clk(hw);
+	int div, rc = 0;
+	struct div_data *data = &d->data;
+
+	div = parent_rate / rate;
+	if (div != data->div)
+		rc = d->ops->set_div(d, div);
+	data->div = div;
+
+	return rc;
+}
+
+static int div_enable(struct clk_hw *hw)
+{
+	struct div_clk *d = to_div_clk(hw);
+	if (d->ops && d->ops->enable)
+		return d->ops->enable(d);
+	return 0;
+}
+
+static void div_disable(struct clk_hw *hw)
+{
+	struct div_clk *d = to_div_clk(hw);
+	if (d->ops && d->ops->disable)
+		return d->ops->disable(d);
+}
+
+static unsigned long div_recalc_rate(struct clk_hw *hw, unsigned long prate)
+{
+	struct div_clk *d = to_div_clk(hw);
+	unsigned int div = d->data.div;
+
+	if (d->ops && d->ops->get_div)
+		div = max(d->ops->get_div(d), 1);
+	div = max(div, 1U);
+
+	if (!d->ops || !d->ops->set_div)
+		d->data.min_div = d->data.max_div = div;
+	d->data.div = div;
+
+	return prate / div;
+}
+
+const struct clk_ops clk_ops_div = {
+	.enable = div_enable,
+	.disable = div_disable,
+	.round_rate = div_round_rate,
+	.set_rate = div_set_rate,
+	.recalc_rate = div_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_ops_div);
+
+/* ==================== Mux_div clock ==================== */
+
+static int mux_div_clk_enable(struct clk_hw *hw)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+
+	if (md->ops->enable)
+		return md->ops->enable(md);
+	return 0;
+}
+
+static void mux_div_clk_disable(struct clk_hw *hw)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+
+	if (md->ops->disable)
+		return md->ops->disable(md);
+}
+
+static long __mux_div_round_rate(struct clk_hw *hw, unsigned long rate,
+	struct clk **best_parent, int *best_div, unsigned long *best_prate)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	unsigned int i;
+	unsigned long rrate, best = 0, _best_div = 0, _best_prate = 0;
+	struct clk *_best_parent = 0;
+	int num_parents = __clk_get_num_parents(hw->clk);
+	bool set_parent = __clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT;
+
+	for (i = 0; i < num_parents; i++) {
+		int div;
+		unsigned long prate;
+		struct clk *p = clk_get_parent_by_index(hw->clk, i);
+
+		rrate = __div_round_rate(&md->data, rate, p, &div, &prate,
+				set_parent);
+
+		if (is_better_rate(rate, best, rrate)) {
+			best = rrate;
+			_best_div = div;
+			_best_prate = prate;
+			_best_parent = p;
+		}
+
+		if (rate <= rrate)
+			break;
+	}
+
+	if (best_div)
+		*best_div = _best_div;
+	if (best_prate)
+		*best_prate = _best_prate;
+	if (best_parent)
+		*best_parent = _best_parent;
+
+	if (best)
+		return best;
+	return -EINVAL;
+}
+
+static long mux_div_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long *parent_rate)
+{
+	return __mux_div_round_rate(hw, rate, NULL, NULL, parent_rate);
+}
+
+/* requires enable lock to be held */
+static int __set_src_div(struct mux_div_clk *md, u8 src_sel, u32 div)
+{
+	int rc;
+
+	rc = md->ops->set_src_div(md, src_sel, div);
+	if (!rc) {
+		md->data.div = div;
+		md->src_sel = src_sel;
+	}
+
+	return rc;
+}
+
+/* Must be called after handoff to ensure parent clock rates are initialized */
+static int safe_parent_init_once(struct clk_hw *hw)
+{
+	unsigned long rrate;
+	u32 best_div;
+	struct clk *best_parent;
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+
+	if (IS_ERR(md->safe_parent))
+		return -EINVAL;
+	if (!md->safe_freq || md->safe_parent)
+		return 0;
+
+	rrate = __mux_div_round_rate(hw, md->safe_freq, &best_parent,
+			&best_div, NULL);
+
+	if (rrate == md->safe_freq) {
+		md->safe_div = best_div;
+		md->safe_parent = best_parent;
+	} else {
+		md->safe_parent = ERR_PTR(-EINVAL);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+__mux_div_clk_set_rate_and_parent(struct clk_hw *hw, u8 index, u32 div)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	int rc;
+
+	rc = safe_parent_init_once(hw);
+	if (rc)
+		return rc;
+
+	return __set_src_div(md, index, div);
+}
+
+static int mux_div_clk_set_rate_and_parent(struct clk_hw *hw,
+		unsigned long rate, unsigned long parent_rate, u8 index)
+{
+	return __mux_div_clk_set_rate_and_parent(hw, index, parent_rate / rate);
+}
+
+static int mux_div_clk_set_rate(struct clk_hw *hw,
+		unsigned long rate, unsigned long parent_rate)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	return __mux_div_clk_set_rate_and_parent(hw, md->src_sel,
+			parent_rate / rate);
+}
+
+static int mux_div_clk_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	return __mux_div_clk_set_rate_and_parent(hw, md->parent_map[index],
+			md->data.div);
+}
+
+static u8 mux_div_clk_get_parent(struct clk_hw *hw)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	int num_parents = __clk_get_num_parents(hw->clk);
+	u32 i, div, sel;
+
+	md->ops->get_src_div(md, &sel, &div);
+	md->src_sel = sel;
+
+	for (i = 0; i < num_parents; i++)
+		if (sel == md->parent_map[i])
+			return i;
+	WARN(1, "Can't find parent\n");
+	return -EINVAL;
+}
+
+static unsigned long
+mux_div_clk_recalc_rate(struct clk_hw *hw, unsigned long prate)
+{
+	struct mux_div_clk *md = to_mux_div_clk(hw);
+	u32 div, sel;
+
+	md->ops->get_src_div(md, &sel, &div);
+
+	return prate / div;
+}
+
+const struct clk_ops clk_ops_mux_div_clk = {
+	.enable = mux_div_clk_enable,
+	.disable = mux_div_clk_disable,
+	.set_rate_and_parent = mux_div_clk_set_rate_and_parent,
+	.set_rate = mux_div_clk_set_rate,
+	.set_parent = mux_div_clk_set_parent,
+	.round_rate = mux_div_clk_round_rate,
+	.get_parent = mux_div_clk_get_parent,
+	.recalc_rate = mux_div_clk_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_ops_mux_div_clk);
diff --git a/include/linux/clk/msm-clk-generic.h b/include/linux/clk/msm-clk-generic.h
new file mode 100644
index 000000000000..cee38636fe0f
--- /dev/null
+++ b/include/linux/clk/msm-clk-generic.h
@@ -0,0 +1,208 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __QCOM_CLK_GENERIC_H__
+#define __QCOM_CLK_GENERIC_H__
+
+#include <linux/err.h>
+#include <linux/clk-provider.h>
+
+static inline bool is_better_rate(unsigned long req, unsigned long best,
+				  unsigned long new)
+{
+	if (IS_ERR_VALUE(new))
+		return false;
+
+	return (req <= new && new < best) || (best < req && best < new);
+}
+
+/* ==================== Mux clock ==================== */
+
+struct mux_clk;
+
+struct clk_mux_ops {
+	int (*set_mux_sel)(struct mux_clk *clk, int sel);
+	int (*get_mux_sel)(struct mux_clk *clk);
+
+	/* Optional */
+	bool (*is_enabled)(struct mux_clk *clk);
+	int (*enable)(struct mux_clk *clk);
+	void (*disable)(struct mux_clk *clk);
+};
+
+struct mux_clk {
+	/* Parents in decreasing order of preference for obtaining rates. */
+	u8 		*parent_map;
+	bool		has_safe_parent;
+	u8		safe_sel;
+	const struct clk_mux_ops *ops;
+
+	/* Fields not used by helper function. */
+	void __iomem 	*base;
+	u32		offset;
+	u32		en_offset;
+	int		en_reg;
+	u32		mask;
+	u32		shift;
+	u32		en_mask;
+	void		*priv;
+
+	struct clk_hw	hw;
+};
+
+static inline struct mux_clk *to_mux_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct mux_clk, hw);
+}
+
+extern const struct clk_ops clk_ops_gen_mux;
+
+/* ==================== Divider clock ==================== */
+
+struct div_clk;
+
+struct clk_div_ops {
+	int (*set_div)(struct div_clk *clk, int div);
+	int (*get_div)(struct div_clk *clk);
+	bool (*is_enabled)(struct div_clk *clk);
+	int (*enable)(struct div_clk *clk);
+	void (*disable)(struct div_clk *clk);
+};
+
+struct div_data {
+	unsigned int div;
+	unsigned int min_div;
+	unsigned int max_div;
+	/*
+	 * Indicate whether this divider clock supports half-interger divider.
+	 * If it is, all the min_div and max_div have been doubled. It means
+	 * they are 2*N.
+	 */
+	bool is_half_divider;
+};
+
+struct div_clk {
+	struct div_data data;
+
+	/* Optional */
+	const struct clk_div_ops *ops;
+
+	/* Fields not used by helper function. */
+	void __iomem 	*base;
+	u32		offset;
+	u32		mask;
+	u32		shift;
+	u32		en_mask;
+	void		*priv;
+	struct clk_hw	hw;
+};
+
+static inline struct div_clk *to_div_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct div_clk, hw);
+}
+
+extern const struct clk_ops clk_ops_div;
+
+#define DEFINE_FIXED_DIV_CLK(clk_name, _div, _parent) \
+static struct div_clk clk_name = {	\
+	.data = {				\
+		.max_div = _div,		\
+		.min_div = _div,		\
+		.div = _div,			\
+	},					\
+	.hw.init = &(struct clk_init_data){ \
+		.parent_names = (const char *[]){ _parent }, \
+		.num_parents = 1,		\
+		.name = #clk_name,		\
+		.ops = &clk_ops_div,		\
+		.flags = CLK_SET_RATE_PARENT,	\
+	}					\
+}
+
+/* ==================== Mux Div clock ==================== */
+
+struct mux_div_clk;
+
+/*
+ * struct mux_div_ops
+ * the enable and disable ops are optional.
+ */
+
+struct mux_div_ops {
+	int (*set_src_div)(struct mux_div_clk *, u32 src_sel, u32 div);
+	void (*get_src_div)(struct mux_div_clk *, u32 *src_sel, u32 *div);
+	int (*enable)(struct mux_div_clk *);
+	void (*disable)(struct mux_div_clk *);
+	bool (*is_enabled)(struct mux_div_clk *);
+};
+
+/*
+ * struct mux_div_clk - combined mux/divider clock
+ * @priv
+		parameters needed by ops
+ * @safe_freq
+		when switching rates from A to B, the mux div clock will
+		instead switch from A -> safe_freq -> B. This allows the
+		mux_div clock to change rates while enabled, even if this
+		behavior is not supported by the parent clocks.
+
+		If changing the rate of parent A also causes the rate of
+		parent B to change, then safe_freq must be defined.
+
+		safe_freq is expected to have a source clock which is always
+		on and runs at only one rate.
+ * @parents
+		list of parents and mux indicies
+ * @ops
+		function pointers for hw specific operations
+ * @src_sel
+		the mux index which will be used if the clock is enabled.
+ */
+
+struct mux_div_clk {
+	/* Required parameters */
+	const struct mux_div_ops	*ops;
+	struct div_data			data;
+	u8				*parent_map;
+
+	struct clk_hw			hw;
+
+	/* Internal */
+	u32				src_sel;
+
+	/* Optional parameters */
+	void				*priv;
+	void __iomem			*base;
+	u32				div_mask;
+	u32				div_offset;
+	u32				div_shift;
+	u32				src_mask;
+	u32				src_offset;
+	u32				src_shift;
+	u32				en_mask;
+	u32				en_offset;
+
+	u32				safe_div;
+	struct clk			*safe_parent;
+	unsigned long			safe_freq;
+};
+
+static inline struct mux_div_clk *to_mux_div_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct mux_div_clk, hw);
+}
+
+extern const struct clk_ops clk_ops_mux_div_clk;
+
+#endif
-- 
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