clk: meson: Add support for Meson clock controller

This patchset adds the infrastructure for registering and managing the
core clocks found on Amlogic MesonX SoCs. In particular:

- PLLs
- CPU clock
- Fixed rate clocks, fixed factor clocks, ...

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

5 files changed, 903 insertions, 0 deletions

diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
new file mode 100644
index 0000000..66c6d8d
--- /dev/null
+++ b/drivers/clk/meson/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for Meson specific clk
+#
+
+obj-y += clkc.o clk-pll.o clk-cpu.o
diff --git a/drivers/clk/meson/clk-cpu.c b/drivers/clk/meson/clk-cpu.c
new file mode 100644
index 0000000..148e99f
--- /dev/null
+++ b/drivers/clk/meson/clk-cpu.c
@@ -0,0 +1,234 @@
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * 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/>.
+ */
+
+/*
+ * CPU clock path:
+ *
+ *                           +-[/N]-----|3|
+ *             MUX2  +--[/3]-+----------|2| MUX1
+ * [sys_pll]---|1|   |--[/2]------------|1|-|1|
+ *             | |---+------------------|0| | |----- [a5_clk]
+ *          +--|0|                          | |
+ * [xtal]---+-------------------------------|0|
+ *
+ *
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/clk-provider.h>
+
+#define MESON_CPU_CLK_CNTL1		0x00
+#define MESON_CPU_CLK_CNTL		0x40
+
+#define MESON_CPU_CLK_MUX1		BIT(7)
+#define MESON_CPU_CLK_MUX2		BIT(0)
+
+#define MESON_N_WIDTH			9
+#define MESON_N_SHIFT			20
+#define MESON_SEL_WIDTH			2
+#define MESON_SEL_SHIFT			2
+
+#include "clkc.h"
+
+struct meson_clk_cpu {
+	struct notifier_block		clk_nb;
+	const struct clk_div_table	*div_table;
+	struct clk_hw			hw;
+	void __iomem			*base;
+	u16				reg_off;
+};
+#define to_meson_clk_cpu_hw(_hw) container_of(_hw, struct meson_clk_cpu, hw)
+#define to_meson_clk_cpu_nb(_nb) container_of(_nb, struct meson_clk_cpu, clk_nb)
+
+static long meson_clk_cpu_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *prate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+
+	return divider_round_rate(hw, rate, prate, clk_cpu->div_table,
+				  MESON_N_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
+}
+
+static int meson_clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+	unsigned int div, sel, N = 0;
+	u32 reg;
+
+	div = DIV_ROUND_UP(parent_rate, rate);
+
+	if (div <= 3) {
+		sel = div - 1;
+	} else {
+		sel = 3;
+		N = div / 2;
+	}
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+	reg = PARM_SET(MESON_N_WIDTH, MESON_N_SHIFT, reg, N);
+	writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+	reg = PARM_SET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg, sel);
+	writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+
+	return 0;
+}
+
+static unsigned long meson_clk_cpu_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+	unsigned int N, sel;
+	unsigned int div = 1;
+	u32 reg;
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+	N = PARM_GET(MESON_N_WIDTH, MESON_N_SHIFT, reg);
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+	sel = PARM_GET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg);
+
+	if (sel < 3)
+		div = sel + 1;
+	else
+		div = 2 * N;
+
+	return parent_rate / div;
+}
+
+static int meson_clk_cpu_pre_rate_change(struct meson_clk_cpu *clk_cpu,
+					 struct clk_notifier_data *ndata)
+{
+	u32 cpu_clk_cntl;
+
+	/* switch MUX1 to xtal */
+	cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	cpu_clk_cntl &= ~MESON_CPU_CLK_MUX1;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	udelay(100);
+
+	/* switch MUX2 to sys-pll */
+	cpu_clk_cntl |= MESON_CPU_CLK_MUX2;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+
+	return 0;
+}
+
+static int meson_clk_cpu_post_rate_change(struct meson_clk_cpu *clk_cpu,
+					  struct clk_notifier_data *ndata)
+{
+	u32 cpu_clk_cntl;
+
+	/* switch MUX1 to divisors' output */
+	cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	cpu_clk_cntl |= MESON_CPU_CLK_MUX1;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	udelay(100);
+
+	return 0;
+}
+
+/*
+ * This clock notifier is called when the frequency of the of the parent
+ * PLL clock is to be changed. We use the xtal input as temporary parent
+ * while the PLL frequency is stabilized.
+ */
+static int meson_clk_cpu_notifier_cb(struct notifier_block *nb,
+				     unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_nb(nb);
+	int ret = 0;
+
+	if (event == PRE_RATE_CHANGE)
+		ret = meson_clk_cpu_pre_rate_change(clk_cpu, ndata);
+	else if (event == POST_RATE_CHANGE)
+		ret = meson_clk_cpu_post_rate_change(clk_cpu, ndata);
+
+	return notifier_from_errno(ret);
+}
+
+static const struct clk_ops meson_clk_cpu_ops = {
+	.recalc_rate	= meson_clk_cpu_recalc_rate,
+	.round_rate	= meson_clk_cpu_round_rate,
+	.set_rate	= meson_clk_cpu_set_rate,
+};
+
+struct clk *meson_clk_register_cpu(const struct clk_conf *clk_conf,
+				   void __iomem *reg_base,
+				   spinlock_t *lock)
+{
+	struct clk *clk;
+	struct clk *pclk;
+	struct meson_clk_cpu *clk_cpu;
+	struct clk_init_data init;
+	int ret;
+
+	clk_cpu = kzalloc(sizeof(*clk_cpu), GFP_KERNEL);
+	if (!clk_cpu)
+		return ERR_PTR(-ENOMEM);
+
+	clk_cpu->base = reg_base;
+	clk_cpu->reg_off = clk_conf->reg_off;
+	clk_cpu->div_table = clk_conf->conf.div_table;
+	clk_cpu->clk_nb.notifier_call = meson_clk_cpu_notifier_cb;
+
+	init.name = clk_conf->clk_name;
+	init.ops = &meson_clk_cpu_ops;
+	init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
+	init.flags |= CLK_SET_RATE_PARENT;
+	init.parent_names = clk_conf->clks_parent;
+	init.num_parents = 1;
+
+	clk_cpu->hw.init = &init;
+
+	pclk = __clk_lookup(clk_conf->clks_parent[0]);
+	if (!pclk) {
+		pr_err("%s: could not lookup parent clock %s\n",
+				__func__, clk_conf->clks_parent[0]);
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = clk_notifier_register(pclk, &clk_cpu->clk_nb);
+	if (ret) {
+		pr_err("%s: failed to register clock notifier for %s\n",
+				__func__, clk_conf->clk_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	clk = clk_register(NULL, &clk_cpu->hw);
+	if (IS_ERR(clk)) {
+		clk_notifier_unregister(pclk, &clk_cpu->clk_nb);
+		kfree(clk_cpu);
+	}
+
+	return clk;
+}
+
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
new file mode 100644
index 0000000..664edf0
--- /dev/null
+++ b/drivers/clk/meson/clk-pll.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * 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/>.
+ */
+
+/*
+ * In the most basic form, a Meson PLL is composed as follows:
+ *
+ *                     PLL
+ *      +------------------------------+
+ *      |                              |
+ * in -----[ /N ]---[ *M ]---[ >>OD ]----->> out
+ *      |         ^        ^           |
+ *      +------------------------------+
+ *                |        |
+ *               FREF     VCO
+ *
+ * out = (in * M / N) >> OD
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "clkc.h"
+
+#define MESON_PLL_RESET				BIT(29)
+#define MESON_PLL_LOCK				BIT(31)
+
+struct meson_clk_pll {
+	struct clk_hw	hw;
+	void __iomem	*base;
+	struct pll_conf	*conf;
+	unsigned int	rate_count;
+	spinlock_t	*lock;
+};
+#define to_meson_clk_pll(_hw) container_of(_hw, struct meson_clk_pll, hw)
+
+static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+	struct parm *p;
+	unsigned long parent_rate_mhz = parent_rate / 1000000;
+	unsigned long rate_mhz;
+	u16 n, m, od;
+	u32 reg;
+
+	p = &pll->conf->n;
+	reg = readl(pll->base + p->reg_off);
+	n = PARM_GET(p->width, p->shift, reg);
+
+	p = &pll->conf->m;
+	reg = readl(pll->base + p->reg_off);
+	m = PARM_GET(p->width, p->shift, reg);
+
+	p = &pll->conf->od;
+	reg = readl(pll->base + p->reg_off);
+	od = PARM_GET(p->width, p->shift, reg);
+
+	rate_mhz = (parent_rate_mhz * m / n) >> od;
+
+	return rate_mhz * 1000000;
+}
+
+static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *parent_rate)
+{
+	struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+	const struct pll_rate_table *rate_table = pll->conf->rate_table;
+	int i;
+
+	for (i = 0; i < pll->rate_count; i++) {
+		if (rate <= rate_table[i].rate)
+			return rate_table[i].rate;
+	}
+
+	/* else return the smallest value */
+	return rate_table[0].rate;
+}
+
+static const struct pll_rate_table *meson_clk_get_pll_settings(struct meson_clk_pll *pll,
+							       unsigned long rate)
+{
+	const struct pll_rate_table *rate_table = pll->conf->rate_table;
+	int i;
+
+	for (i = 0; i < pll->rate_count; i++) {
+		if (rate == rate_table[i].rate)
+			return &rate_table[i];
+	}
+	return NULL;
+}
+
+static int meson_clk_pll_wait_lock(struct meson_clk_pll *pll,
+				   struct parm *p_n)
+{
+	int delay = 24000000;
+	u32 reg;
+
+	while (delay > 0) {
+		reg = readl(pll->base + p_n->reg_off);
+
+		if (reg & MESON_PLL_LOCK)
+			return 0;
+		delay--;
+	}
+	return -ETIMEDOUT;
+}
+
+static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+	struct parm *p;
+	const struct pll_rate_table *rate_set;
+	unsigned long old_rate;
+	int ret = 0;
+	u32 reg;
+
+	if (parent_rate == 0 || rate == 0)
+		return -EINVAL;
+
+	old_rate = rate;
+
+	rate_set = meson_clk_get_pll_settings(pll, rate);
+	if (!rate_set)
+		return -EINVAL;
+
+	/* PLL reset */
+	p = &pll->conf->n;
+	reg = readl(pll->base + p->reg_off);
+	writel(reg | MESON_PLL_RESET, pll->base + p->reg_off);
+
+	reg = PARM_SET(p->width, p->shift, reg, rate_set->n);
+	writel(reg, pll->base + p->reg_off);
+
+	p = &pll->conf->m;
+	reg = readl(pll->base + p->reg_off);
+	reg = PARM_SET(p->width, p->shift, reg, rate_set->m);
+	writel(reg, pll->base + p->reg_off);
+
+	p = &pll->conf->od;
+	reg = readl(pll->base + p->reg_off);
+	reg = PARM_SET(p->width, p->shift, reg, rate_set->od);
+	writel(reg, pll->base + p->reg_off);
+
+	p = &pll->conf->n;
+	ret = meson_clk_pll_wait_lock(pll, p);
+	if (ret) {
+		pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
+			__func__, old_rate);
+		meson_clk_pll_set_rate(hw, old_rate, parent_rate);
+	}
+
+	return ret;
+}
+
+static const struct clk_ops meson_clk_pll_ops = {
+	.recalc_rate	= meson_clk_pll_recalc_rate,
+	.round_rate	= meson_clk_pll_round_rate,
+	.set_rate	= meson_clk_pll_set_rate,
+};
+
+static const struct clk_ops meson_clk_pll_ro_ops = {
+	.recalc_rate	= meson_clk_pll_recalc_rate,
+};
+
+struct clk *meson_clk_register_pll(const struct clk_conf *clk_conf,
+				   void __iomem *reg_base,
+				   spinlock_t *lock)
+{
+	struct clk *clk;
+	struct meson_clk_pll *clk_pll;
+	struct clk_init_data init;
+
+	clk_pll = kzalloc(sizeof(*clk_pll), GFP_KERNEL);
+	if (!clk_pll)
+		return ERR_PTR(-ENOMEM);
+
+	clk_pll->base = reg_base + clk_conf->reg_off;
+	clk_pll->lock = lock;
+	clk_pll->conf = clk_conf->conf.pll;
+
+	init.name = clk_conf->clk_name;
+	init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
+
+	init.parent_names = &clk_conf->clks_parent[0];
+	init.num_parents = 1;
+	init.ops = &meson_clk_pll_ro_ops;
+
+	/* If no rate_table is specified we assume the PLL is read-only */
+	if (clk_pll->conf->rate_table) {
+		int len;
+
+		for (len = 0; clk_pll->conf->rate_table[len].rate != 0; )
+			len++;
+
+		 clk_pll->rate_count = len;
+		 init.ops = &meson_clk_pll_ops;
+	}
+
+	clk_pll->hw.init = &init;
+
+	clk = clk_register(NULL, &clk_pll->hw);
+	if (IS_ERR(clk))
+		kfree(clk_pll);
+
+	return clk;
+}
diff --git a/drivers/clk/meson/clkc.c b/drivers/clk/meson/clkc.c
new file mode 100644
index 0000000..b8c511c
--- /dev/null
+++ b/drivers/clk/meson/clkc.c
@@ -0,0 +1,250 @@
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * 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/mfd/syscon.h>
+#include <linux/slab.h>
+
+#include "clkc.h"
+
+static DEFINE_SPINLOCK(clk_lock);
+
+static struct clk **clks;
+static struct clk_onecell_data clk_data;
+
+struct clk ** __init meson_clk_init(struct device_node *np,
+				   unsigned long nr_clks)
+{
+	clks = kcalloc(nr_clks, sizeof(*clks), GFP_KERNEL);
+	if (!clks)
+		return ERR_PTR(-ENOMEM);
+
+	clk_data.clks = clks;
+	clk_data.clk_num = nr_clks;
+	of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+
+	return clks;
+}
+
+static void meson_clk_add_lookup(struct clk *clk, unsigned int id)
+{
+	if (clks && id)
+		clks[id] = clk;
+}
+
+static struct clk * __init
+meson_clk_register_composite(const struct clk_conf *clk_conf,
+			     void __iomem *clk_base)
+{
+	struct clk *clk;
+	struct clk_mux *mux = NULL;
+	struct clk_divider *div = NULL;
+	struct clk_gate *gate = NULL;
+	const struct clk_ops *mux_ops = NULL;
+	const struct composite_conf *composite_conf;
+
+	composite_conf = clk_conf->conf.composite;
+
+	if (clk_conf->num_parents > 1) {
+		mux = kzalloc(sizeof(*mux), GFP_KERNEL);
+		if (!mux)
+			return ERR_PTR(-ENOMEM);
+
+		mux->reg = clk_base + clk_conf->reg_off
+				+ composite_conf->mux_parm.reg_off;
+		mux->shift = composite_conf->mux_parm.shift;
+		mux->mask = BIT(composite_conf->mux_parm.width) - 1;
+		mux->flags = composite_conf->mux_flags;
+		mux->lock = &clk_lock;
+		mux->table = composite_conf->mux_table;
+		mux_ops = (composite_conf->mux_flags & CLK_MUX_READ_ONLY) ?
+			  &clk_mux_ro_ops : &clk_mux_ops;
+	}
+
+	if (MESON_PARM_APPLICABLE(&composite_conf->div_parm)) {
+		div = kzalloc(sizeof(*div), GFP_KERNEL);
+		if (!div) {
+			clk = ERR_PTR(-ENOMEM);
+			goto error;
+		}
+
+		div->reg = clk_base + clk_conf->reg_off
+				+ composite_conf->div_parm.reg_off;
+		div->shift = composite_conf->div_parm.shift;
+		div->width = composite_conf->div_parm.width;
+		div->lock = &clk_lock;
+		div->flags = composite_conf->div_flags;
+		div->table = composite_conf->div_table;
+	}
+
+	if (MESON_PARM_APPLICABLE(&composite_conf->gate_parm)) {
+		gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+		if (!gate) {
+			clk = ERR_PTR(-ENOMEM);
+			goto error;
+		}
+
+		gate->reg = clk_base + clk_conf->reg_off
+				+ composite_conf->div_parm.reg_off;
+		gate->bit_idx = composite_conf->gate_parm.shift;
+		gate->flags = composite_conf->gate_flags;
+		gate->lock = &clk_lock;
+	}
+
+	clk = clk_register_composite(NULL, clk_conf->clk_name,
+				    clk_conf->clks_parent,
+				    clk_conf->num_parents,
+				    mux ? &mux->hw : NULL, mux_ops,
+				    div ? &div->hw : NULL, &clk_divider_ops,
+				    gate ? &gate->hw : NULL, &clk_gate_ops,
+				    clk_conf->flags);
+	if (IS_ERR(clk))
+		goto error;
+
+	return clk;
+
+error:
+	kfree(gate);
+	kfree(div);
+	kfree(mux);
+
+	return clk;
+}
+
+static struct clk * __init
+meson_clk_register_fixed_factor(const struct clk_conf *clk_conf,
+				void __iomem *clk_base)
+{
+	struct clk *clk;
+	const struct fixed_fact_conf *fixed_fact_conf;
+	const struct parm *p;
+	unsigned int mult, div;
+	u32 reg;
+
+	fixed_fact_conf = &clk_conf->conf.fixed_fact;
+
+	mult = clk_conf->conf.fixed_fact.mult;
+	div = clk_conf->conf.fixed_fact.div;
+
+	if (!mult) {
+		mult = 1;
+		p = &fixed_fact_conf->mult_parm;
+		if (MESON_PARM_APPLICABLE(p)) {
+			reg = readl(clk_base + clk_conf->reg_off + p->reg_off);
+			mult = PARM_GET(p->width, p->shift, reg);
+		}
+	}
+
+	if (!div) {
+		div = 1;
+		p = &fixed_fact_conf->div_parm;
+		if (MESON_PARM_APPLICABLE(p)) {
+			reg = readl(clk_base + clk_conf->reg_off + p->reg_off);
+			mult = PARM_GET(p->width, p->shift, reg);
+		}
+	}
+
+	clk = clk_register_fixed_factor(NULL,
+			clk_conf->clk_name,
+			clk_conf->clks_parent[0],
+			clk_conf->flags,
+			mult, div);
+
+	return clk;
+}
+
+static struct clk * __init
+meson_clk_register_fixed_rate(const struct clk_conf *clk_conf,
+			      void __iomem *clk_base)
+{
+	struct clk *clk;
+	const struct fixed_rate_conf *fixed_rate_conf;
+	const struct parm *r;
+	unsigned long rate;
+	u32 reg;
+
+	fixed_rate_conf = &clk_conf->conf.fixed_rate;
+	rate = fixed_rate_conf->rate;
+
+	if (!rate) {
+		r = &fixed_rate_conf->rate_parm;
+		reg = readl(clk_base + clk_conf->reg_off + r->reg_off);
+		rate = PARM_GET(r->width, r->shift, reg);
+	}
+
+	rate *= 1000000;
+
+	clk = clk_register_fixed_rate(NULL,
+			clk_conf->clk_name,
+			clk_conf->num_parents
+				? clk_conf->clks_parent[0] : NULL,
+			clk_conf->flags, rate);
+
+	return clk;
+}
+
+void __init meson_clk_register_clks(const struct clk_conf *clk_confs,
+				    size_t nr_confs,
+				    void __iomem *clk_base)
+{
+	unsigned int i;
+	struct clk *clk = NULL;
+
+	for (i = 0; i < nr_confs; i++) {
+		const struct clk_conf *clk_conf = &clk_confs[i];
+
+		switch (clk_conf->clk_type) {
+		case CLK_FIXED_RATE:
+			clk = meson_clk_register_fixed_rate(clk_conf,
+							    clk_base);
+			break;
+		case CLK_FIXED_FACTOR:
+			clk = meson_clk_register_fixed_factor(clk_conf,
+							      clk_base);
+			break;
+		case CLK_COMPOSITE:
+			clk = meson_clk_register_composite(clk_conf,
+							   clk_base);
+			break;
+		case CLK_CPU:
+			clk = meson_clk_register_cpu(clk_conf, clk_base,
+						     &clk_lock);
+			break;
+		case CLK_PLL:
+			clk = meson_clk_register_pll(clk_conf, clk_base,
+						     &clk_lock);
+			break;
+		default:
+			clk = NULL;
+		}
+
+		if (!clk) {
+			pr_err("%s: unknown clock type %d\n", __func__,
+			       clk_conf->clk_type);
+			continue;
+		}
+
+		if (IS_ERR(clk)) {
+			pr_warn("%s: Unable to create %s clock\n", __func__,
+				clk_conf->clk_name);
+			continue;
+		}
+
+		meson_clk_add_lookup(clk, clk_conf->clk_id);
+	}
+}
diff --git a/drivers/clk/meson/clkc.h b/drivers/clk/meson/clkc.h
new file mode 100644
index 0000000..609ae92
--- /dev/null
+++ b/drivers/clk/meson/clkc.h
@@ -0,0 +1,187 @@
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * 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/>.
+ */
+
+#ifndef __CLKC_H
+#define __CLKC_H
+
+#define PMASK(width)			GENMASK(width - 1, 0)
+#define SETPMASK(width, shift)		GENMASK(shift + width - 1, shift)
+#define CLRPMASK(width, shift)		(~SETPMASK(width, shift))
+
+#define PARM_GET(width, shift, reg)					\
+	(((reg) & SETPMASK(width, shift)) >> (shift))
+#define PARM_SET(width, shift, reg, val)				\
+	(((reg) & CLRPMASK(width, shift)) | (val << (shift)))
+
+#define MESON_PARM_APPLICABLE(p)		(!!((p)->width))
+
+struct parm {
+	u16	reg_off;
+	u8	shift;
+	u8	width;
+};
+#define PARM(_r, _s, _w)						\
+	{								\
+		.reg_off	= (_r),					\
+		.shift		= (_s),					\
+		.width		= (_w),					\
+	}								\
+
+struct pll_rate_table {
+	unsigned long	rate;
+	u16		m;
+	u16		n;
+	u16		od;
+};
+#define PLL_RATE(_r, _m, _n, _od)					\
+	{								\
+		.rate		= (_r),					\
+		.m		= (_m),					\
+		.n		= (_n),					\
+		.od		= (_od),				\
+	}								\
+
+struct pll_conf {
+	const struct pll_rate_table	*rate_table;
+	struct parm			m;
+	struct parm			n;
+	struct parm			od;
+};
+
+struct fixed_fact_conf {
+	unsigned int	div;
+	unsigned int	mult;
+	struct parm	div_parm;
+	struct parm	mult_parm;
+};
+
+struct fixed_rate_conf {
+	unsigned long	rate;
+	struct parm	rate_parm;
+};
+
+struct composite_conf {
+	struct parm		mux_parm;
+	struct parm		div_parm;
+	struct parm		gate_parm;
+	struct clk_div_table	*div_table;
+	u32			*mux_table;
+	u8			mux_flags;
+	u8			div_flags;
+	u8			gate_flags;
+};
+
+#define PNAME(x) static const char *x[]
+
+enum clk_type {
+	CLK_FIXED_FACTOR,
+	CLK_FIXED_RATE,
+	CLK_COMPOSITE,
+	CLK_CPU,
+	CLK_PLL,
+};
+
+struct clk_conf {
+	u16				reg_off;
+	enum clk_type			clk_type;
+	unsigned int			clk_id;
+	const char			*clk_name;
+	const char			**clks_parent;
+	int				num_parents;
+	unsigned long			flags;
+	union {
+		struct fixed_fact_conf		fixed_fact;
+		struct fixed_rate_conf		fixed_rate;
+		const struct composite_conf		*composite;
+		struct pll_conf			*pll;
+		const struct clk_div_table	*div_table;
+	} conf;
+};
+
+#define FIXED_RATE_P(_ro, _ci, _cn, _f, _c)				\
+	{								\
+		.reg_off			= (_ro),		\
+		.clk_type			= CLK_FIXED_RATE,	\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.flags				= (_f),			\
+		.conf.fixed_rate.rate_parm	= _c,			\
+	}								\
+
+#define FIXED_RATE(_ci, _cn, _f, _r)					\
+	{								\
+		.clk_type			= CLK_FIXED_RATE,	\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.flags				= (_f),			\
+		.conf.fixed_rate.rate		= (_r),			\
+	}								\
+
+#define PLL(_ro, _ci, _cn, _cp, _f, _c)					\
+	{								\
+		.reg_off			= (_ro),		\
+		.clk_type			= CLK_PLL,		\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.clks_parent			= (_cp),		\
+		.num_parents			= ARRAY_SIZE(_cp),	\
+		.flags				= (_f),			\
+		.conf.pll			= (_c),			\
+	}								\
+
+#define FIXED_FACTOR_DIV(_ci, _cn, _cp, _f, _d)				\
+	{								\
+		.clk_type			= CLK_FIXED_FACTOR,	\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.clks_parent			= (_cp),		\
+		.num_parents			= ARRAY_SIZE(_cp),	\
+		.conf.fixed_fact.div		= (_d),			\
+	}								\
+
+#define CPU(_ro, _ci, _cn, _cp, _dt)					\
+	{								\
+		.reg_off			= (_ro),		\
+		.clk_type			= CLK_CPU,		\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.clks_parent			= (_cp),		\
+		.num_parents			= ARRAY_SIZE(_cp),	\
+		.conf.div_table			= (_dt),		\
+	}								\
+
+#define COMPOSITE(_ro, _ci, _cn, _cp, _f, _c)				\
+	{								\
+		.reg_off			= (_ro),		\
+		.clk_type			= CLK_COMPOSITE,	\
+		.clk_id				= (_ci),		\
+		.clk_name			= (_cn),		\
+		.clks_parent			= (_cp),		\
+		.num_parents			= ARRAY_SIZE(_cp),	\
+		.flags				= (_f),			\
+		.conf.composite			= (_c),			\
+	}								\
+
+struct clk **meson_clk_init(struct device_node *np, unsigned long nr_clks);
+void meson_clk_register_clks(const struct clk_conf *clk_confs,
+			     unsigned int nr_confs, void __iomem *clk_base);
+struct clk *meson_clk_register_cpu(const struct clk_conf *clk_conf,
+				   void __iomem *reg_base, spinlock_t *lock);
+struct clk *meson_clk_register_pll(const struct clk_conf *clk_conf,
+				   void __iomem *reg_base, spinlock_t *lock);
+
+#endif /* __CLKC_H */