clk: ingenic: add driver for Ingenic SoC CGU clocks

This driver supports the CGU clocks for Ingenic SoCs. It is generic
enough to be usable across at least the JZ4740 to the JZ4780, and will
be made use of on such devices in subsequent commits. This patch by
itself only adds the SoC-agnostic infrastructure that forms the bulk of
the CGU driver for the aforementioned further commits to make use of.

Signed-off-by: Paul Burton <[e-mail]>
Co-authored-by: Paul Cercueil <[e-mail]>
Cc: Lars-Peter Clausen <[e-mail]>
Cc: Mike Turquette <[e-mail]>
Cc: Stephen Boyd <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/10150/
Signed-off-by: Ralf Baechle <[e-mail]>

drivers/clk/Makefile

···
 obj-$(CONFIG_ARCH_HI3xxx)		+= hisilicon/
 obj-$(CONFIG_ARCH_HIP04)		+= hisilicon/
 obj-$(CONFIG_ARCH_HIX5HD2)		+= hisilicon/
+obj-$(CONFIG_MACH_INGENIC)		+= ingenic/
 obj-$(CONFIG_COMMON_CLK_KEYSTONE)	+= keystone/
 ifeq ($(CONFIG_COMMON_CLK), y)
 obj-$(CONFIG_ARCH_MMP)			+= mmp/

drivers/clk/ingenic/Makefile

···
+obj-y				+= cgu.o

drivers/clk/ingenic/cgu.c

···
+/*
+ * Ingenic SoC CGU driver
+ *
+ * Copyright (c) 2013-2015 Imagination Technologies
+ * Author: Paul Burton <[e-mail]>
+ *
+ * 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/bitops.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/delay.h>
+#include <linux/math64.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include "cgu.h"
+
+#define MHZ (1000 * 1000)
+
+/**
+ * ingenic_cgu_gate_get() - get the value of clock gate register bit
+ * @cgu: reference to the CGU whose registers should be read
+ * @info: info struct describing the gate bit
+ *
+ * Retrieves the state of the clock gate bit described by info. The
+ * caller must hold cgu->lock.
+ *
+ * Return: true if the gate bit is set, else false.
+ */
+static inline bool
+ingenic_cgu_gate_get(struct ingenic_cgu *cgu,
+		     const struct ingenic_cgu_gate_info *info)
+{
+	return readl(cgu->base + info->reg) & BIT(info->bit);
+}
+
+/**
+ * ingenic_cgu_gate_set() - set the value of clock gate register bit
+ * @cgu: reference to the CGU whose registers should be modified
+ * @info: info struct describing the gate bit
+ * @val: non-zero to gate a clock, otherwise zero
+ *
+ * Sets the given gate bit in order to gate or ungate a clock.
+ *
+ * The caller must hold cgu->lock.
+ */
+static inline void
+ingenic_cgu_gate_set(struct ingenic_cgu *cgu,
+		     const struct ingenic_cgu_gate_info *info, bool val)
+{
+	u32 clkgr = readl(cgu->base + info->reg);
+
+	if (val)
+		clkgr |= BIT(info->bit);
+	else
+		clkgr &= ~BIT(info->bit);
+
+	writel(clkgr, cgu->base + info->reg);
+}
+
+/*
+ * PLL operations
+ */
+
+static unsigned long
+ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	const struct ingenic_cgu_pll_info *pll_info;
+	unsigned m, n, od_enc, od;
+	bool bypass, enable;
+	unsigned long flags;
+	u32 ctl;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+	BUG_ON(clk_info->type != CGU_CLK_PLL);
+	pll_info = &clk_info->pll;
+
+	spin_lock_irqsave(&cgu->lock, flags);
+	ctl = readl(cgu->base + pll_info->reg);
+	spin_unlock_irqrestore(&cgu->lock, flags);
+
+	m = (ctl >> pll_info->m_shift) & GENMASK(pll_info->m_bits - 1, 0);
+	m += pll_info->m_offset;
+	n = (ctl >> pll_info->n_shift) & GENMASK(pll_info->n_bits - 1, 0);
+	n += pll_info->n_offset;
+	od_enc = ctl >> pll_info->od_shift;
+	od_enc &= GENMASK(pll_info->od_bits - 1, 0);
+	bypass = !!(ctl & BIT(pll_info->bypass_bit));
+	enable = !!(ctl & BIT(pll_info->enable_bit));
+
+	if (bypass)
+		return parent_rate;
+
+	if (!enable)
+		return 0;
+
+	for (od = 0; od < pll_info->od_max; od++) {
+		if (pll_info->od_encoding[od] == od_enc)
+			break;
+	}
+	BUG_ON(od == pll_info->od_max);
+	od++;
+
+	return div_u64((u64)parent_rate * m, n * od);
+}
+
+static unsigned long
+ingenic_pll_calc(const struct ingenic_cgu_clk_info *clk_info,
+		 unsigned long rate, unsigned long parent_rate,
+		 unsigned *pm, unsigned *pn, unsigned *pod)
+{
+	const struct ingenic_cgu_pll_info *pll_info;
+	unsigned m, n, od;
+
+	pll_info = &clk_info->pll;
+	od = 1;
+
+	/*
+	 * The frequency after the input divider must be between 10 and 50 MHz.
+	 * The highest divider yields the best resolution.
+	 */
+	n = parent_rate / (10 * MHZ);
+	n = min_t(unsigned, n, 1 << clk_info->pll.n_bits);
+	n = max_t(unsigned, n, pll_info->n_offset);
+
+	m = (rate / MHZ) * od * n / (parent_rate / MHZ);
+	m = min_t(unsigned, m, 1 << clk_info->pll.m_bits);
+	m = max_t(unsigned, m, pll_info->m_offset);
+
+	if (pm)
+		*pm = m;
+	if (pn)
+		*pn = n;
+	if (pod)
+		*pod = od;
+
+	return div_u64((u64)parent_rate * m, n * od);
+}
+
+static long
+ingenic_pll_round_rate(struct clk_hw *hw, unsigned long req_rate,
+		       unsigned long *prate)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+	BUG_ON(clk_info->type != CGU_CLK_PLL);
+
+	return ingenic_pll_calc(clk_info, req_rate, *prate, NULL, NULL, NULL);
+}
+
+static int
+ingenic_pll_set_rate(struct clk_hw *hw, unsigned long req_rate,
+		     unsigned long parent_rate)
+{
+	const unsigned timeout = 100;
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	const struct ingenic_cgu_pll_info *pll_info;
+	unsigned long rate, flags;
+	unsigned m, n, od, i;
+	u32 ctl;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+	BUG_ON(clk_info->type != CGU_CLK_PLL);
+	pll_info = &clk_info->pll;
+
+	rate = ingenic_pll_calc(clk_info, req_rate, parent_rate,
+			       &m, &n, &od);
+	if (rate != req_rate)
+		pr_info("ingenic-cgu: request '%s' rate %luHz, actual %luHz\n",
+			clk_info->name, req_rate, rate);
+
+	spin_lock_irqsave(&cgu->lock, flags);
+	ctl = readl(cgu->base + pll_info->reg);
+
+	ctl &= ~(GENMASK(pll_info->m_bits - 1, 0) << pll_info->m_shift);
+	ctl |= (m - pll_info->m_offset) << pll_info->m_shift;
+
+	ctl &= ~(GENMASK(pll_info->n_bits - 1, 0) << pll_info->n_shift);
+	ctl |= (n - pll_info->n_offset) << pll_info->n_shift;
+
+	ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << pll_info->od_shift);
+	ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift;
+
+	ctl &= ~BIT(pll_info->bypass_bit);
+	ctl |= BIT(pll_info->enable_bit);
+
+	writel(ctl, cgu->base + pll_info->reg);
+
+	/* wait for the PLL to stabilise */
+	for (i = 0; i < timeout; i++) {
+		ctl = readl(cgu->base + pll_info->reg);
+		if (ctl & BIT(pll_info->stable_bit))
+			break;
+		mdelay(1);
+	}
+
+	spin_unlock_irqrestore(&cgu->lock, flags);
+
+	if (i == timeout)
+		return -EBUSY;
+
+	return 0;
+}
+
+static const struct clk_ops ingenic_pll_ops = {
+	.recalc_rate = ingenic_pll_recalc_rate,
+	.round_rate = ingenic_pll_round_rate,
+	.set_rate = ingenic_pll_set_rate,
+};
+
+/*
+ * Operations for all non-PLL clocks
+ */
+
+static u8 ingenic_clk_get_parent(struct clk_hw *hw)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	u32 reg;
+	u8 i, hw_idx, idx = 0;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_MUX) {
+		reg = readl(cgu->base + clk_info->mux.reg);
+		hw_idx = (reg >> clk_info->mux.shift) &
+			 GENMASK(clk_info->mux.bits - 1, 0);
+
+		/*
+		 * Convert the hardware index to the parent index by skipping
+		 * over any -1's in the parents array.
+		 */
+		for (i = 0; i < hw_idx; i++) {
+			if (clk_info->parents[i] != -1)
+				idx++;
+		}
+	}
+
+	return idx;
+}
+
+static int ingenic_clk_set_parent(struct clk_hw *hw, u8 idx)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	unsigned long flags;
+	u8 curr_idx, hw_idx, num_poss;
+	u32 reg, mask;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_MUX) {
+		/*
+		 * Convert the parent index to the hardware index by adding
+		 * 1 for any -1 in the parents array preceding the given
+		 * index. That is, we want the index of idx'th entry in
+		 * clk_info->parents which does not equal -1.
+		 */
+		hw_idx = curr_idx = 0;
+		num_poss = 1 << clk_info->mux.bits;
+		for (; hw_idx < num_poss; hw_idx++) {
+			if (clk_info->parents[hw_idx] == -1)
+				continue;
+			if (curr_idx == idx)
+				break;
+			curr_idx++;
+		}
+
+		/* idx should always be a valid parent */
+		BUG_ON(curr_idx != idx);
+
+		mask = GENMASK(clk_info->mux.bits - 1, 0);
+		mask <<= clk_info->mux.shift;
+
+		spin_lock_irqsave(&cgu->lock, flags);
+
+		/* write the register */
+		reg = readl(cgu->base + clk_info->mux.reg);
+		reg &= ~mask;
+		reg |= hw_idx << clk_info->mux.shift;
+		writel(reg, cgu->base + clk_info->mux.reg);
+
+		spin_unlock_irqrestore(&cgu->lock, flags);
+		return 0;
+	}
+
+	return idx ? -EINVAL : 0;
+}
+
+static unsigned long
+ingenic_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	unsigned long rate = parent_rate;
+	u32 div_reg, div;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_DIV) {
+		div_reg = readl(cgu->base + clk_info->div.reg);
+		div = (div_reg >> clk_info->div.shift) &
+		      GENMASK(clk_info->div.bits - 1, 0);
+		div += 1;
+
+		rate /= div;
+	}
+
+	return rate;
+}
+
+static unsigned
+ingenic_clk_calc_div(const struct ingenic_cgu_clk_info *clk_info,
+		     unsigned long parent_rate, unsigned long req_rate)
+{
+	unsigned div;
+
+	/* calculate the divide */
+	div = DIV_ROUND_UP(parent_rate, req_rate);
+
+	/* and impose hardware constraints */
+	div = min_t(unsigned, div, 1 << clk_info->div.bits);
+	div = max_t(unsigned, div, 1);
+
+	return div;
+}
+
+static long
+ingenic_clk_round_rate(struct clk_hw *hw, unsigned long req_rate,
+		       unsigned long *parent_rate)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	long rate = *parent_rate;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_DIV)
+		rate /= ingenic_clk_calc_div(clk_info, *parent_rate, req_rate);
+	else if (clk_info->type & CGU_CLK_FIXDIV)
+		rate /= clk_info->fixdiv.div;
+
+	return rate;
+}
+
+static int
+ingenic_clk_set_rate(struct clk_hw *hw, unsigned long req_rate,
+		     unsigned long parent_rate)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	const unsigned timeout = 100;
+	unsigned long rate, flags;
+	unsigned div, i;
+	u32 reg, mask;
+	int ret = 0;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_DIV) {
+		div = ingenic_clk_calc_div(clk_info, parent_rate, req_rate);
+		rate = parent_rate / div;
+
+		if (rate != req_rate)
+			return -EINVAL;
+
+		spin_lock_irqsave(&cgu->lock, flags);
+		reg = readl(cgu->base + clk_info->div.reg);
+
+		/* update the divide */
+		mask = GENMASK(clk_info->div.bits - 1, 0);
+		reg &= ~(mask << clk_info->div.shift);
+		reg |= (div - 1) << clk_info->div.shift;
+
+		/* clear the stop bit */
+		if (clk_info->div.stop_bit != -1)
+			reg &= ~BIT(clk_info->div.stop_bit);
+
+		/* set the change enable bit */
+		if (clk_info->div.ce_bit != -1)
+			reg |= BIT(clk_info->div.ce_bit);
+
+		/* update the hardware */
+		writel(reg, cgu->base + clk_info->div.reg);
+
+		/* wait for the change to take effect */
+		if (clk_info->div.busy_bit != -1) {
+			for (i = 0; i < timeout; i++) {
+				reg = readl(cgu->base + clk_info->div.reg);
+				if (!(reg & BIT(clk_info->div.busy_bit)))
+					break;
+				mdelay(1);
+			}
+			if (i == timeout)
+				ret = -EBUSY;
+		}
+
+		spin_unlock_irqrestore(&cgu->lock, flags);
+		return ret;
+	}
+
+	return -EINVAL;
+}
+
+static int ingenic_clk_enable(struct clk_hw *hw)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	unsigned long flags;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_GATE) {
+		/* ungate the clock */
+		spin_lock_irqsave(&cgu->lock, flags);
+		ingenic_cgu_gate_set(cgu, &clk_info->gate, false);
+		spin_unlock_irqrestore(&cgu->lock, flags);
+	}
+
+	return 0;
+}
+
+static void ingenic_clk_disable(struct clk_hw *hw)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	unsigned long flags;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_GATE) {
+		/* gate the clock */
+		spin_lock_irqsave(&cgu->lock, flags);
+		ingenic_cgu_gate_set(cgu, &clk_info->gate, true);
+		spin_unlock_irqrestore(&cgu->lock, flags);
+	}
+}
+
+static int ingenic_clk_is_enabled(struct clk_hw *hw)
+{
+	struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
+	struct ingenic_cgu *cgu = ingenic_clk->cgu;
+	const struct ingenic_cgu_clk_info *clk_info;
+	unsigned long flags;
+	int enabled = 1;
+
+	clk_info = &cgu->clock_info[ingenic_clk->idx];
+
+	if (clk_info->type & CGU_CLK_GATE) {
+		spin_lock_irqsave(&cgu->lock, flags);
+		enabled = !ingenic_cgu_gate_get(cgu, &clk_info->gate);
+		spin_unlock_irqrestore(&cgu->lock, flags);
+	}
+
+	return enabled;
+}
+
+static const struct clk_ops ingenic_clk_ops = {
+	.get_parent = ingenic_clk_get_parent,
+	.set_parent = ingenic_clk_set_parent,
+
+	.recalc_rate = ingenic_clk_recalc_rate,
+	.round_rate = ingenic_clk_round_rate,
+	.set_rate = ingenic_clk_set_rate,
+
+	.enable = ingenic_clk_enable,
+	.disable = ingenic_clk_disable,
+	.is_enabled = ingenic_clk_is_enabled,
+};
+
+/*
+ * Setup functions.
+ */
+
+static int ingenic_register_clock(struct ingenic_cgu *cgu, unsigned idx)
+{
+	const struct ingenic_cgu_clk_info *clk_info = &cgu->clock_info[idx];
+	struct clk_init_data clk_init;
+	struct ingenic_clk *ingenic_clk = NULL;
+	struct clk *clk, *parent;
+	const char *parent_names[4];
+	unsigned caps, i, num_possible;
+	int err = -EINVAL;
+
+	BUILD_BUG_ON(ARRAY_SIZE(clk_info->parents) > ARRAY_SIZE(parent_names));
+
+	if (clk_info->type == CGU_CLK_EXT) {
+		clk = of_clk_get_by_name(cgu->np, clk_info->name);
+		if (IS_ERR(clk)) {
+			pr_err("%s: no external clock '%s' provided\n",
+			       __func__, clk_info->name);
+			err = -ENODEV;
+			goto out;
+		}
+		err = clk_register_clkdev(clk, clk_info->name, NULL);
+		if (err) {
+			clk_put(clk);
+			goto out;
+		}
+		cgu->clocks.clks[idx] = clk;
+		return 0;
+	}
+
+	if (!clk_info->type) {
+		pr_err("%s: no clock type specified for '%s'\n", __func__,
+		       clk_info->name);
+		goto out;
+	}
+
+	ingenic_clk = kzalloc(sizeof(*ingenic_clk), GFP_KERNEL);
+	if (!ingenic_clk) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	ingenic_clk->hw.init = &clk_init;
+	ingenic_clk->cgu = cgu;
+	ingenic_clk->idx = idx;
+
+	clk_init.name = clk_info->name;
+	clk_init.flags = 0;
+	clk_init.parent_names = parent_names;
+
+	caps = clk_info->type;
+
+	if (caps & (CGU_CLK_MUX | CGU_CLK_CUSTOM)) {
+		clk_init.num_parents = 0;
+
+		if (caps & CGU_CLK_MUX)
+			num_possible = 1 << clk_info->mux.bits;
+		else
+			num_possible = ARRAY_SIZE(clk_info->parents);
+
+		for (i = 0; i < num_possible; i++) {
+			if (clk_info->parents[i] == -1)
+				continue;
+
+			parent = cgu->clocks.clks[clk_info->parents[i]];
+			parent_names[clk_init.num_parents] =
+				__clk_get_name(parent);
+			clk_init.num_parents++;
+		}
+
+		BUG_ON(!clk_init.num_parents);
+		BUG_ON(clk_init.num_parents > ARRAY_SIZE(parent_names));
+	} else {
+		BUG_ON(clk_info->parents[0] == -1);
+		clk_init.num_parents = 1;
+		parent = cgu->clocks.clks[clk_info->parents[0]];
+		parent_names[0] = __clk_get_name(parent);
+	}
+
+	if (caps & CGU_CLK_CUSTOM) {
+		clk_init.ops = clk_info->custom.clk_ops;
+
+		caps &= ~CGU_CLK_CUSTOM;
+
+		if (caps) {
+			pr_err("%s: custom clock may not be combined with type 0x%x\n",
+			       __func__, caps);
+			goto out;
+		}
+	} else if (caps & CGU_CLK_PLL) {
+		clk_init.ops = &ingenic_pll_ops;
+
+		caps &= ~CGU_CLK_PLL;
+
+		if (caps) {
+			pr_err("%s: PLL may not be combined with type 0x%x\n",
+			       __func__, caps);
+			goto out;
+		}
+	} else {
+		clk_init.ops = &ingenic_clk_ops;
+	}
+
+	/* nothing to do for gates or fixed dividers */
+	caps &= ~(CGU_CLK_GATE | CGU_CLK_FIXDIV);
+
+	if (caps & CGU_CLK_MUX) {
+		if (!(caps & CGU_CLK_MUX_GLITCHFREE))
+			clk_init.flags |= CLK_SET_PARENT_GATE;
+
+		caps &= ~(CGU_CLK_MUX | CGU_CLK_MUX_GLITCHFREE);
+	}
+
+	if (caps & CGU_CLK_DIV) {
+		caps &= ~CGU_CLK_DIV;
+	} else {
+		/* pass rate changes to the parent clock */
+		clk_init.flags |= CLK_SET_RATE_PARENT;
+	}
+
+	if (caps) {
+		pr_err("%s: unknown clock type 0x%x\n", __func__, caps);
+		goto out;
+	}
+
+	clk = clk_register(NULL, &ingenic_clk->hw);
+	if (IS_ERR(clk)) {
+		pr_err("%s: failed to register clock '%s'\n", __func__,
+		       clk_info->name);
+		err = PTR_ERR(clk);
+		goto out;
+	}
+
+	err = clk_register_clkdev(clk, clk_info->name, NULL);
+	if (err)
+		goto out;
+
+	cgu->clocks.clks[idx] = clk;
+out:
+	if (err)
+		kfree(ingenic_clk);
+	return err;
+}
+
+struct ingenic_cgu *
+ingenic_cgu_new(const struct ingenic_cgu_clk_info *clock_info,
+		unsigned num_clocks, struct device_node *np)
+{
+	struct ingenic_cgu *cgu;
+
+	cgu = kzalloc(sizeof(*cgu), GFP_KERNEL);
+	if (!cgu)
+		goto err_out;
+
+	cgu->base = of_iomap(np, 0);
+	if (!cgu->base) {
+		pr_err("%s: failed to map CGU registers\n", __func__);
+		goto err_out_free;
+	}
+
+	cgu->np = np;
+	cgu->clock_info = clock_info;
+	cgu->clocks.clk_num = num_clocks;
+
+	spin_lock_init(&cgu->lock);
+
+	return cgu;
+
+err_out_free:
+	kfree(cgu);
+err_out:
+	return NULL;
+}
+
+int ingenic_cgu_register_clocks(struct ingenic_cgu *cgu)
+{
+	unsigned i;
+	int err;
+
+	cgu->clocks.clks = kcalloc(cgu->clocks.clk_num, sizeof(struct clk *),
+				   GFP_KERNEL);
+	if (!cgu->clocks.clks) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	for (i = 0; i < cgu->clocks.clk_num; i++) {
+		err = ingenic_register_clock(cgu, i);
+		if (err)
+			goto err_out_unregister;
+	}
+
+	err = of_clk_add_provider(cgu->np, of_clk_src_onecell_get,
+				  &cgu->clocks);
+	if (err)
+		goto err_out_unregister;
+
+	return 0;
+
+err_out_unregister:
+	for (i = 0; i < cgu->clocks.clk_num; i++) {
+		if (!cgu->clocks.clks[i])
+			continue;
+		if (cgu->clock_info[i].type & CGU_CLK_EXT)
+			clk_put(cgu->clocks.clks[i]);
+		else
+			clk_unregister(cgu->clocks.clks[i]);
+	}
+	kfree(cgu->clocks.clks);
+err_out:
+	return err;
+}

drivers/clk/ingenic/cgu.h

···
+/*
+ * Ingenic SoC CGU driver
+ *
+ * Copyright (c) 2013-2015 Imagination Technologies
+ * Author: Paul Burton <[e-mail]>
+ *
+ * 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.
+ */
+
+#ifndef __DRIVERS_CLK_INGENIC_CGU_H__
+#define __DRIVERS_CLK_INGENIC_CGU_H__
+
+#include <linux/bitops.h>
+#include <linux/of.h>
+#include <linux/spinlock.h>
+
+/**
+ * struct ingenic_cgu_pll_info - information about a PLL
+ * @reg: the offset of the PLL's control register within the CGU
+ * @m_shift: the number of bits to shift the multiplier value by (ie. the
+ *           index of the lowest bit of the multiplier value in the PLL's
+ *           control register)
+ * @m_bits: the size of the multiplier field in bits
+ * @m_offset: the multiplier value which encodes to 0 in the PLL's control
+ *            register
+ * @n_shift: the number of bits to shift the divider value by (ie. the
+ *           index of the lowest bit of the divider value in the PLL's
+ *           control register)
+ * @n_bits: the size of the divider field in bits
+ * @n_offset: the divider value which encodes to 0 in the PLL's control
+ *            register
+ * @od_shift: the number of bits to shift the post-VCO divider value by (ie.
+ *            the index of the lowest bit of the post-VCO divider value in
+ *            the PLL's control register)
+ * @od_bits: the size of the post-VCO divider field in bits
+ * @od_max: the maximum post-VCO divider value
+ * @od_encoding: a pointer to an array mapping post-VCO divider values to
+ *               their encoded values in the PLL control register, or -1 for
+ *               unsupported values
+ * @bypass_bit: the index of the bypass bit in the PLL control register
+ * @enable_bit: the index of the enable bit in the PLL control register
+ * @stable_bit: the index of the stable bit in the PLL control register
+ */
+struct ingenic_cgu_pll_info {
+	unsigned reg;
+	const s8 *od_encoding;
+	u8 m_shift, m_bits, m_offset;
+	u8 n_shift, n_bits, n_offset;
+	u8 od_shift, od_bits, od_max;
+	u8 bypass_bit;
+	u8 enable_bit;
+	u8 stable_bit;
+};
+
+/**
+ * struct ingenic_cgu_mux_info - information about a clock mux
+ * @reg: offset of the mux control register within the CGU
+ * @shift: number of bits to shift the mux value by (ie. the index of
+ *         the lowest bit of the mux value within its control register)
+ * @bits: the size of the mux value in bits
+ */
+struct ingenic_cgu_mux_info {
+	unsigned reg;
+	u8 shift;
+	u8 bits;
+};
+
+/**
+ * struct ingenic_cgu_div_info - information about a divider
+ * @reg: offset of the divider control register within the CGU
+ * @shift: number of bits to shift the divide value by (ie. the index of
+ *         the lowest bit of the divide value within its control register)
+ * @bits: the size of the divide value in bits
+ * @ce_bit: the index of the change enable bit within reg, or -1 if there
+ *          isn't one
+ * @busy_bit: the index of the busy bit within reg, or -1 if there isn't one
+ * @stop_bit: the index of the stop bit within reg, or -1 if there isn't one
+ */
+struct ingenic_cgu_div_info {
+	unsigned reg;
+	u8 shift;
+	u8 bits;
+	s8 ce_bit;
+	s8 busy_bit;
+	s8 stop_bit;
+};
+
+/**
+ * struct ingenic_cgu_fixdiv_info - information about a fixed divider
+ * @div: the divider applied to the parent clock
+ */
+struct ingenic_cgu_fixdiv_info {
+	unsigned div;
+};
+
+/**
+ * struct ingenic_cgu_gate_info - information about a clock gate
+ * @reg: offset of the gate control register within the CGU
+ * @bit: offset of the bit in the register that controls the gate
+ */
+struct ingenic_cgu_gate_info {
+	unsigned reg;
+	u8 bit;
+};
+
+/**
+ * struct ingenic_cgu_custom_info - information about a custom (SoC) clock
+ * @clk_ops: custom clock operation callbacks
+ */
+struct ingenic_cgu_custom_info {
+	struct clk_ops *clk_ops;
+};
+
+/**
+ * struct ingenic_cgu_clk_info - information about a clock
+ * @name: name of the clock
+ * @type: a bitmask formed from CGU_CLK_* values
+ * @parents: an array of the indices of potential parents of this clock
+ *           within the clock_info array of the CGU, or -1 in entries
+ *           which correspond to no valid parent
+ * @pll: information valid if type includes CGU_CLK_PLL
+ * @gate: information valid if type includes CGU_CLK_GATE
+ * @mux: information valid if type includes CGU_CLK_MUX
+ * @div: information valid if type includes CGU_CLK_DIV
+ * @fixdiv: information valid if type includes CGU_CLK_FIXDIV
+ * @custom: information valid if type includes CGU_CLK_CUSTOM
+ */
+struct ingenic_cgu_clk_info {
+	const char *name;
+
+	enum {
+		CGU_CLK_NONE		= 0,
+		CGU_CLK_EXT		= BIT(0),
+		CGU_CLK_PLL		= BIT(1),
+		CGU_CLK_GATE		= BIT(2),
+		CGU_CLK_MUX		= BIT(3),
+		CGU_CLK_MUX_GLITCHFREE	= BIT(4),
+		CGU_CLK_DIV		= BIT(5),
+		CGU_CLK_FIXDIV		= BIT(6),
+		CGU_CLK_CUSTOM		= BIT(7),
+	} type;
+
+	int parents[4];
+
+	union {
+		struct ingenic_cgu_pll_info pll;
+
+		struct {
+			struct ingenic_cgu_gate_info gate;
+			struct ingenic_cgu_mux_info mux;
+			struct ingenic_cgu_div_info div;
+			struct ingenic_cgu_fixdiv_info fixdiv;
+		};
+
+		struct ingenic_cgu_custom_info custom;
+	};
+};
+
+/**
+ * struct ingenic_cgu - data about the CGU
+ * @np: the device tree node that caused the CGU to be probed
+ * @base: the ioremap'ed base address of the CGU registers
+ * @clock_info: an array containing information about implemented clocks
+ * @clocks: used to provide clocks to DT, allows lookup of struct clk*
+ * @lock: lock to be held whilst manipulating CGU registers
+ */
+struct ingenic_cgu {
+	struct device_node *np;
+	void __iomem *base;
+
+	const struct ingenic_cgu_clk_info *clock_info;
+	struct clk_onecell_data clocks;
+
+	spinlock_t lock;
+};
+
+/**
+ * struct ingenic_clk - private data for a clock
+ * @hw: see Documentation/clk.txt
+ * @cgu: a pointer to the CGU data
+ * @idx: the index of this clock in cgu->clock_info
+ */
+struct ingenic_clk {
+	struct clk_hw hw;
+	struct ingenic_cgu *cgu;
+	unsigned idx;
+};
+
+#define to_ingenic_clk(_hw) container_of(_hw, struct ingenic_clk, hw)
+
+/**
+ * ingenic_cgu_new() - create a new CGU instance
+ * @clock_info: an array of clock information structures describing the clocks
+ *              which are implemented by the CGU
+ * @num_clocks: the number of entries in clock_info
+ * @np: the device tree node which causes this CGU to be probed
+ *
+ * Return: a pointer to the CGU instance if initialisation is successful,
+ *         otherwise NULL.
+ */
+struct ingenic_cgu *
+ingenic_cgu_new(const struct ingenic_cgu_clk_info *clock_info,
+		unsigned num_clocks, struct device_node *np);
+
+/**
+ * ingenic_cgu_register_clocks() - Registers the clocks
+ * @cgu: pointer to cgu data
+ *
+ * Register the clocks described by the CGU with the common clock framework.
+ *
+ * Return: 0 on success or -errno if unsuccesful.
+ */
+int ingenic_cgu_register_clocks(struct ingenic_cgu *cgu);
+
+#endif /* __DRIVERS_CLK_INGENIC_CGU_H__ */