clk: rockchip: add basic infrastructure for clock branches

This adds infrastructure for registering clock branches. On Rockchip SoCs
most clock branches are a combination of mux,divider and gate components,
thus a composite clock is used when appropriate.

Clock branches are supposed to be declared in an array using the COMPOSITE*
or MUX, etc makros defined in the header and then registered using
rockchip_clk_register_branches.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-By: Max Schwarz <max.schwarz@online.de>
Tested-By: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/rockchip/Makefile

@@ -3,3 +3,4 @@
 #
 
 obj-y	+= clk-rockchip.o
+obj-y	+= clk.o

drivers/clk/rockchip/clk.c

@@ -0,0 +1,209 @@
+/*
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on
+ *
+ * samsung/clk.c
+ * Copyright (c) 2013 Samsung Electronics Co., Ltd.
+ * Copyright (c) 2013 Linaro Ltd.
+ * Author: Thomas Abraham <thomas.ab@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/slab.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include "clk.h"
+
+/**
+ * Register a clock branch.
+ * Most clock branches have a form like
+ *
+ * src1 --|--\
+ *        |M |--[GATE]-[DIV]-
+ * src2 --|--/
+ *
+ * sometimes without one of those components.
+ */
+struct clk *rockchip_clk_register_branch(const char *name,
+		const char **parent_names, u8 num_parents, void __iomem *base,
+		int muxdiv_offset, u8 mux_shift, u8 mux_width, u8 mux_flags,
+		u8 div_shift, u8 div_width, u8 div_flags,
+		struct clk_div_table *div_table, int gate_offset,
+		u8 gate_shift, u8 gate_flags, unsigned long flags,
+		spinlock_t *lock)
+{
+	struct clk *clk;
+	struct clk_mux *mux = NULL;
+	struct clk_gate *gate = NULL;
+	struct clk_divider *div = NULL;
+	const struct clk_ops *mux_ops = NULL, *div_ops = NULL,
+			     *gate_ops = NULL;
+
+	if (num_parents > 1) {
+		mux = kzalloc(sizeof(*mux), GFP_KERNEL);
+		if (!mux)
+			return ERR_PTR(-ENOMEM);
+
+		mux->reg = base + muxdiv_offset;
+		mux->shift = mux_shift;
+		mux->mask = BIT(mux_width) - 1;
+		mux->flags = mux_flags;
+		mux->lock = lock;
+		mux_ops = (mux_flags & CLK_MUX_READ_ONLY) ? &clk_mux_ro_ops
+							: &clk_mux_ops;
+	}
+
+	if (gate_offset >= 0) {
+		gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+		if (!gate)
+			return ERR_PTR(-ENOMEM);
+
+		gate->flags = gate_flags;
+		gate->reg = base + gate_offset;
+		gate->bit_idx = gate_shift;
+		gate->lock = lock;
+		gate_ops = &clk_gate_ops;
+	}
+
+	if (div_width > 0) {
+		div = kzalloc(sizeof(*div), GFP_KERNEL);
+		if (!div)
+			return ERR_PTR(-ENOMEM);
+
+		div->flags = div_flags;
+		div->reg = base + muxdiv_offset;
+		div->shift = div_shift;
+		div->width = div_width;
+		div->lock = lock;
+		div->table = div_table;
+		div_ops = (div_flags & CLK_DIVIDER_READ_ONLY)
+						? &clk_divider_ro_ops
+						: &clk_divider_ops;
+	}
+
+	clk = clk_register_composite(NULL, name, parent_names, num_parents,
+				     mux ? &mux->hw : NULL, mux_ops,
+				     div ? &div->hw : NULL, div_ops,
+				     gate ? &gate->hw : NULL, gate_ops,
+				     flags);
+
+	return clk;
+}
+
+static DEFINE_SPINLOCK(clk_lock);
+static struct clk **clk_table;
+static void __iomem *reg_base;
+static struct clk_onecell_data clk_data;
+
+void __init rockchip_clk_init(struct device_node *np, void __iomem *base,
+			      unsigned long nr_clks)
+{
+	reg_base = base;
+
+	clk_table = kcalloc(nr_clks, sizeof(struct clk *), GFP_KERNEL);
+	if (!clk_table)
+		pr_err("%s: could not allocate clock lookup table\n", __func__);
+
+	clk_data.clks = clk_table;
+	clk_data.clk_num = nr_clks;
+	of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+}
+
+void rockchip_clk_add_lookup(struct clk *clk, unsigned int id)
+{
+	if (clk_table && id)
+		clk_table[id] = clk;
+}
+
+void __init rockchip_clk_register_branches(
+				      struct rockchip_clk_branch *list,
+				      unsigned int nr_clk)
+{
+	struct clk *clk = NULL;
+	unsigned int idx;
+	unsigned long flags;
+
+	for (idx = 0; idx < nr_clk; idx++, list++) {
+		flags = list->flags;
+
+		/* catch simple muxes */
+		switch (list->branch_type) {
+		case branch_mux:
+			clk = clk_register_mux(NULL, list->name,
+				list->parent_names, list->num_parents,
+				flags, reg_base + list->muxdiv_offset,
+				list->mux_shift, list->mux_width,
+				list->mux_flags, &clk_lock);
+			break;
+		case branch_divider:
+			if (list->div_table)
+				clk = clk_register_divider_table(NULL,
+					list->name, list->parent_names[0],
+					flags, reg_base + list->muxdiv_offset,
+					list->div_shift, list->div_width,
+					list->div_flags, list->div_table,
+					&clk_lock);
+			else
+				clk = clk_register_divider(NULL, list->name,
+					list->parent_names[0], flags,
+					reg_base + list->muxdiv_offset,
+					list->div_shift, list->div_width,
+					list->div_flags, &clk_lock);
+			break;
+		case branch_fraction_divider:
+			/* unimplemented */
+			continue;
+			break;
+		case branch_gate:
+			flags |= CLK_SET_RATE_PARENT;
+
+			/* keep all gates untouched for now */
+			flags |= CLK_IGNORE_UNUSED;
+
+			clk = clk_register_gate(NULL, list->name,
+				list->parent_names[0], flags,
+				reg_base + list->gate_offset,
+				list->gate_shift, list->gate_flags, &clk_lock);
+			break;
+		case branch_composite:
+			/* keep all gates untouched for now */
+			flags |= CLK_IGNORE_UNUSED;
+
+			clk = rockchip_clk_register_branch(list->name,
+				list->parent_names, list->num_parents,
+				reg_base, list->muxdiv_offset, list->mux_shift,
+				list->mux_width, list->mux_flags,
+				list->div_shift, list->div_width,
+				list->div_flags, list->div_table,
+				list->gate_offset, list->gate_shift,
+				list->gate_flags, flags, &clk_lock);
+			break;
+		}
+
+		/* none of the cases above matched */
+		if (!clk) {
+			pr_err("%s: unknown clock type %d\n",
+			       __func__, list->branch_type);
+			continue;
+		}
+
+		if (IS_ERR(clk)) {
+			pr_err("%s: failed to register clock %s: %ld\n",
+			       __func__, list->name, PTR_ERR(clk));
+			continue;
+		}
+
+		rockchip_clk_add_lookup(clk, list->id);
+	}
+}