clk: Add composite clock type

Not all clocks are required to be decomposed into basic clock
types but at the same time want to use the functionality
provided by these basic clock types instead of duplicating.

For example, Tegra SoC has ~100 clocks which can be decomposed
into Mux -> Div -> Gate clock types making the clock count to
~300. Also, parent change operation can not be performed on gate
clock which forces to use mux clock in driver if want to change
the parent.

Instead aggregate the basic clock types functionality into one
clock and just use this clock for all operations. This clock
type re-uses the functionality of basic clock types and not
limited to basic clock types but any hardware-specific
implementation.
Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/Makefile

@@ -7,6 +7,7 @@ obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-factor.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-rate.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-gate.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-mux.o
+obj-$(CONFIG_COMMON_CLK)	+= clk-composite.o
 
 # SoCs specific
 obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835.o

drivers/clk/clk-composite.c

+/*
+ * Copyright (c) 2013 NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+
+#define to_clk_composite(_hw) container_of(_hw, struct clk_composite, hw)
+
+static u8 clk_composite_get_parent(struct clk_hw *hw)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *mux_ops = composite->mux_ops;
+	struct clk_hw *mux_hw = composite->mux_hw;
+
+	mux_hw->clk = hw->clk;
+
+	return mux_ops->get_parent(mux_hw);
+}
+
+static int clk_composite_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *mux_ops = composite->mux_ops;
+	struct clk_hw *mux_hw = composite->mux_hw;
+
+	mux_hw->clk = hw->clk;
+
+	return mux_ops->set_parent(mux_hw, index);
+}
+
+static unsigned long clk_composite_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *div_ops = composite->div_ops;
+	struct clk_hw *div_hw = composite->div_hw;
+
+	div_hw->clk = hw->clk;
+
+	return div_ops->recalc_rate(div_hw, parent_rate);
+}
+
+static long clk_composite_round_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long *prate)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *div_ops = composite->div_ops;
+	struct clk_hw *div_hw = composite->div_hw;
+
+	div_hw->clk = hw->clk;
+
+	return div_ops->round_rate(div_hw, rate, prate);
+}
+
+static int clk_composite_set_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long parent_rate)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *div_ops = composite->div_ops;
+	struct clk_hw *div_hw = composite->div_hw;
+
+	div_hw->clk = hw->clk;
+
+	return div_ops->set_rate(div_hw, rate, parent_rate);
+}
+
+static int clk_composite_is_enabled(struct clk_hw *hw)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *gate_ops = composite->gate_ops;
+	struct clk_hw *gate_hw = composite->gate_hw;
+
+	gate_hw->clk = hw->clk;
+
+	return gate_ops->is_enabled(gate_hw);
+}
+
+static int clk_composite_enable(struct clk_hw *hw)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *gate_ops = composite->gate_ops;
+	struct clk_hw *gate_hw = composite->gate_hw;
+
+	gate_hw->clk = hw->clk;
+
+	return gate_ops->enable(gate_hw);
+}
+
+static void clk_composite_disable(struct clk_hw *hw)
+{
+	struct clk_composite *composite = to_clk_composite(hw);
+	const struct clk_ops *gate_ops = composite->gate_ops;
+	struct clk_hw *gate_hw = composite->gate_hw;
+
+	gate_hw->clk = hw->clk;
+
+	gate_ops->disable(gate_hw);
+}
+
+struct clk *clk_register_composite(struct device *dev, const char *name,
+			const char **parent_names, int num_parents,
+			struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
+			struct clk_hw *div_hw, const struct clk_ops *div_ops,
+			struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
+			unsigned long flags)
+{
+	struct clk *clk;
+	struct clk_init_data init;
+	struct clk_composite *composite;
+	struct clk_ops *clk_composite_ops;
+
+	composite = kzalloc(sizeof(*composite), GFP_KERNEL);
+	if (!composite) {
+		pr_err("%s: could not allocate composite clk\n", __func__);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	init.name = name;
+	init.flags = flags | CLK_IS_BASIC;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+
+	clk_composite_ops = &composite->ops;
+
+	if (mux_hw && mux_ops) {
+		if (!mux_ops->get_parent || !mux_ops->set_parent) {
+			clk = ERR_PTR(-EINVAL);
+			goto err;
+		}
+
+		composite->mux_hw = mux_hw;
+		composite->mux_ops = mux_ops;
+		clk_composite_ops->get_parent = clk_composite_get_parent;
+		clk_composite_ops->set_parent = clk_composite_set_parent;
+	}
+
+	if (div_hw && div_ops) {
+		if (!div_ops->recalc_rate || !div_ops->round_rate ||
+		    !div_ops->set_rate) {
+			clk = ERR_PTR(-EINVAL);
+			goto err;
+		}
+
+		composite->div_hw = div_hw;
+		composite->div_ops = div_ops;
+		clk_composite_ops->recalc_rate = clk_composite_recalc_rate;
+		clk_composite_ops->round_rate = clk_composite_round_rate;
+		clk_composite_ops->set_rate = clk_composite_set_rate;
+	}
+
+	if (gate_hw && gate_ops) {
+		if (!gate_ops->is_enabled || !gate_ops->enable ||
+		    !gate_ops->disable) {
+			clk = ERR_PTR(-EINVAL);
+			goto err;
+		}
+
+		composite->gate_hw = gate_hw;
+		composite->gate_ops = gate_ops;
+		clk_composite_ops->is_enabled = clk_composite_is_enabled;
+		clk_composite_ops->enable = clk_composite_enable;
+		clk_composite_ops->disable = clk_composite_disable;
+	}
+
+	init.ops = clk_composite_ops;
+	composite->hw.init = &init;
+
+	clk = clk_register(dev, &composite->hw);
+	if (IS_ERR(clk))
+		goto err;
+
+	if (composite->mux_hw)
+		composite->mux_hw->clk = clk;
+
+	if (composite->div_hw)
+		composite->div_hw->clk = clk;
+
+	if (composite->gate_hw)
+		composite->gate_hw->clk = clk;
+
+	return clk;
+
+err:
+	kfree(composite);
+	return clk;
+}

include/linux/clk-provider.h

@@ -342,6 +342,37 @@ struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		unsigned int mult, unsigned int div);
 
+/***
+ * struct clk_composite - aggregate clock of mux, divider and gate clocks
+ *
+ * @hw:		handle between common and hardware-specific interfaces
+ * @mux_hw:	handle between composite and hardware-specifix mux clock
+ * @div_hw:	handle between composite and hardware-specifix divider clock
+ * @gate_hw:	handle between composite and hardware-specifix gate clock
+ * @mux_ops:	clock ops for mux
+ * @div_ops:	clock ops for divider
+ * @gate_ops:	clock ops for gate
+ */
+struct clk_composite {
+	struct clk_hw	hw;
+	struct clk_ops	ops;
+
+	struct clk_hw	*mux_hw;
+	struct clk_hw	*div_hw;
+	struct clk_hw	*gate_hw;
+
+	const struct clk_ops	*mux_ops;
+	const struct clk_ops	*div_ops;
+	const struct clk_ops	*gate_ops;
+};
+
+struct clk *clk_register_composite(struct device *dev, const char *name,
+		const char **parent_names, int num_parents,
+		struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
+		struct clk_hw *div_hw, const struct clk_ops *div_ops,
+		struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
+		unsigned long flags);
+
 /**
  * clk_register - allocate a new clock, register it and return an opaque cookie
  * @dev: device that is registering this clock