[PATCH v11 4/6] clk: qcom: Add regmap mux-div clocks support

[Georgi Djakov <georgi.djakov@linaro.org>]

Add support for hardware that can switch both parent clock and divider
at the same time. This avoids generating intermediate frequencies from
either the old parent clock and new divider or new parent clock and
old divider combinations.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 drivers/clk/qcom/Makefile             |   1 +
 drivers/clk/qcom/clk-regmap-mux-div.c | 229 ++++++++++++++++++++++++++++++++++
 drivers/clk/qcom/clk-regmap-mux-div.h |  46 +++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/clk/qcom/clk-regmap-mux-div.c
 create mode 100644 drivers/clk/qcom/clk-regmap-mux-div.h

diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index e767c60c24ec..7c51d877f967 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -10,6 +10,7 @@ clk-qcom-y += clk-rcg2.o
 clk-qcom-y += clk-branch.o
 clk-qcom-y += clk-regmap-divider.o
 clk-qcom-y += clk-regmap-mux.o
+clk-qcom-y += clk-regmap-mux-div.o
 clk-qcom-y += reset.o
 clk-qcom-$(CONFIG_QCOM_GDSC) += gdsc.o
 
diff --git a/drivers/clk/qcom/clk-regmap-mux-div.c b/drivers/clk/qcom/clk-regmap-mux-div.c
new file mode 100644
index 000000000000..c5d6fff29598
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap-mux-div.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017, Linaro Limited
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/regmap.h>
+
+#include "clk-regmap-mux-div.h"
+
+#define CMD_RCGR			0x0
+#define CMD_RCGR_UPDATE			BIT(0)
+#define CMD_RCGR_DIRTY_CFG		BIT(4)
+#define CMD_RCGR_ROOT_OFF		BIT(31)
+#define CFG_RCGR			0x4
+
+#define to_clk_regmap_mux_div(_hw) \
+	container_of(to_clk_regmap(_hw), struct clk_regmap_mux_div, clkr)
+
+int __mux_div_set_src_div(struct clk_regmap_mux_div *md, u32 src, u32 div)
+{
+	int ret, count;
+	u32 val, mask;
+	const char *name = clk_hw_get_name(&md->clkr.hw);
+
+	val = (div << md->hid_shift) | (src << md->src_shift);
+	mask = ((BIT(md->hid_width) - 1) << md->hid_shift) |
+	       ((BIT(md->src_width) - 1) << md->src_shift);
+
+	ret = regmap_update_bits(md->clkr.regmap, CFG_RCGR + md->reg_offset,
+				 mask, val);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(md->clkr.regmap, CMD_RCGR + md->reg_offset,
+				 CMD_RCGR_UPDATE, CMD_RCGR_UPDATE);
+	if (ret)
+		return ret;
+
+	// Wait for update to take effect
+	for (count = 500; count > 0; count--) {
+		ret = regmap_read(md->clkr.regmap, CMD_RCGR + md->reg_offset,
+				  &val);
+		if (ret)
+			return ret;
+		if (!(val & CMD_RCGR_UPDATE))
+			return 0;
+		udelay(1);
+	}
+
+	pr_err("%s: RCG did not update its configuration", name);
+	return -EBUSY;
+}
+
+static void __mux_div_get_src_div(struct clk_regmap_mux_div *md, u32 *src,
+				  u32 *div)
+{
+	u32 val, d, s;
+	const char *name = clk_hw_get_name(&md->clkr.hw);
+
+	regmap_read(md->clkr.regmap, CMD_RCGR + md->reg_offset, &val);
+
+	if (val & CMD_RCGR_DIRTY_CFG) {
+		pr_err("%s: RCG configuration is pending\n", name);
+		return;
+	}
+
+	regmap_read(md->clkr.regmap, CFG_RCGR + md->reg_offset, &val);
+	s = (val >> md->src_shift);
+	s &= BIT(md->src_width) - 1;
+	*src = s;
+
+	d = (val >> md->hid_shift);
+	d &= BIT(md->hid_width) - 1;
+	*div = d;
+}
+
+static inline bool is_better_rate(unsigned long req, unsigned long best,
+				  unsigned long new)
+{
+	return (req <= new && new < best) || (best < req && best < new);
+}
+
+static int mux_div_determine_rate(struct clk_hw *hw,
+				  struct clk_rate_request *req)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+	unsigned int i, div, max_div;
+	unsigned long actual_rate, best_rate = 0;
+	unsigned long req_rate = req->rate;
+
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
+		unsigned long parent_rate = clk_hw_get_rate(parent);
+
+		max_div = BIT(md->hid_width) - 1;
+		for (div = 1; div < max_div; div++) {
+			parent_rate = mult_frac(req_rate, div, 2);
+			parent_rate = clk_hw_round_rate(parent, parent_rate);
+			actual_rate = mult_frac(parent_rate, 2, div);
+
+			if (is_better_rate(req_rate, best_rate, actual_rate)) {
+				best_rate = actual_rate;
+				req->rate = best_rate;
+				req->best_parent_rate = parent_rate;
+				req->best_parent_hw = parent;
+			}
+
+			if (actual_rate < req_rate || best_rate <= req_rate)
+				break;
+		}
+	}
+
+	if (!best_rate)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int __mux_div_set_rate_and_parent(struct clk_hw *hw, unsigned long rate,
+					 unsigned long prate, u32 src)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+	int ret;
+	u32 div, max_div, best_src = 0, best_div = 0;
+	unsigned int i;
+	unsigned long actual_rate, best_rate = 0;
+
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
+		unsigned long parent_rate = clk_hw_get_rate(parent);
+
+		max_div = BIT(md->hid_width) - 1;
+		for (div = 1; div < max_div; div++) {
+			parent_rate = mult_frac(rate, div, 2);
+			parent_rate = clk_hw_round_rate(parent, parent_rate);
+			actual_rate = mult_frac(parent_rate, 2, div);
+
+			if (is_better_rate(rate, best_rate, actual_rate)) {
+				best_rate = actual_rate;
+				best_src = md->parent_map[i].cfg;
+				best_div = div - 1;
+			}
+
+			if (actual_rate < rate || best_rate <= rate)
+				break;
+		}
+	}
+
+	ret = __mux_div_set_src_div(md, best_src, best_div);
+	if (!ret) {
+		md->div = best_div;
+		md->src = best_src;
+	}
+
+	return ret;
+}
+
+static u8 mux_div_get_parent(struct clk_hw *hw)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+	const char *name = clk_hw_get_name(hw);
+	u32 i, div, src = 0;
+
+	__mux_div_get_src_div(md, &src, &div);
+
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++)
+		if (src == md->parent_map[i].cfg)
+			return i;
+
+	pr_err("%s: Can't find parent with src %d\n", name, src);
+	return 0;
+}
+
+static int mux_div_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+
+	return __mux_div_set_src_div(md, md->parent_map[index].cfg, md->div);
+}
+
+static int mux_div_set_rate(struct clk_hw *hw,
+			    unsigned long rate, unsigned long prate)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+
+	return __mux_div_set_rate_and_parent(hw, rate, prate, md->src);
+}
+
+static int mux_div_set_rate_and_parent(struct clk_hw *hw,  unsigned long rate,
+				       unsigned long prate, u8 index)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+
+	return __mux_div_set_rate_and_parent(hw, rate, prate,
+					     md->parent_map[index].cfg);
+}
+
+static unsigned long mux_div_recalc_rate(struct clk_hw *hw, unsigned long prate)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+	u32 div, src;
+	int i, num_parents = clk_hw_get_num_parents(hw);
+	const char *name = clk_hw_get_name(hw);
+
+	__mux_div_get_src_div(md, &src, &div);
+	for (i = 0; i < num_parents; i++)
+		if (src == md->parent_map[i].cfg) {
+			struct clk_hw *p = clk_hw_get_parent_by_index(hw, i);
+			unsigned long parent_rate = clk_hw_get_rate(p);
+
+			return mult_frac(parent_rate, 2, div + 1);
+		}
+
+	pr_err("%s: Can't find parent %d\n", name, src);
+	return 0;
+}
+
+const struct clk_ops clk_regmap_mux_div_ops = {
+	.get_parent = mux_div_get_parent,
+	.set_parent = mux_div_set_parent,
+	.set_rate = mux_div_set_rate,
+	.set_rate_and_parent = mux_div_set_rate_and_parent,
+	.determine_rate = mux_div_determine_rate,
+	.recalc_rate = mux_div_recalc_rate,
+};
diff --git a/drivers/clk/qcom/clk-regmap-mux-div.h b/drivers/clk/qcom/clk-regmap-mux-div.h
new file mode 100644
index 000000000000..a35da978d6c9
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap-mux-div.h
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017, Linaro Limited
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#ifndef __QCOM_CLK_REGMAP_MUX_DIV_H__
+#define __QCOM_CLK_REGMAP_MUX_DIV_H__
+
+#include <linux/clk-provider.h>
+#include "clk-rcg.h"
+#include "clk-regmap.h"
+
+/**
+ * struct mux_div_clk - combined mux/divider clock
+ * @reg_offset: offset of the mux/divider register
+ * @hid_width:	number of bits in half integer divider
+ * @hid_shift:	lowest bit of hid value field
+ * @src_width:	number of bits in source select
+ * @src_shift:	lowest bit of source select field
+ * @div:	the divider raw configuration value
+ * @src:	the mux index which will be used if the clock is enabled
+ * @parent_map:	pointer to parent_map struct
+ * @clkr:	handle between common and hardware-specific interfaces
+ * @pclk:	the input PLL clock
+ * @clk_nb:	clock notifier for rate changes of the input PLL
+ */
+
+struct clk_regmap_mux_div {
+	u32				reg_offset;
+	u32				hid_width;
+	u32				hid_shift;
+	u32				src_width;
+	u32				src_shift;
+	u32				div;
+	u32				src;
+	const struct parent_map		*parent_map;
+	struct clk_regmap		clkr;
+	struct clk			*pclk;
+	struct notifier_block		clk_nb;
+};
+
+extern const struct clk_ops clk_regmap_mux_div_ops;
+int __mux_div_set_src_div(struct clk_regmap_mux_div *md, u32 src, u32 div);
+
+#endif