[PATCH v5 0/3] Add support for Qualcomm A53 CPU clock

[PATCH v5 0/3] Add support for Qualcomm A53 CPU clock

[Georgi Djakov]

This patchset adds support for the A53 CPU clock and allows scaling
of the CPU frequency on msm8916 based platforms.

Changes since v4 (https://lkml.org/lkml/2015/12/14/367)
 * Convert to builtin drivers as now __clk_lookup() is used

Changes since v3 (https://lkml.org/lkml/2015/8/12/585)
 * Split driver into two parts - and separate A53 PLL and
   A53 clock controller drivers.
 * Drop the safe switch hook patch. Add a clock notifier in
   the clock provider to handle switching via safe mux and
   divider configuration.

Changes since v2 (https://lkml.org/lkml/2015/7/24/526)
 * Drop gpll0_vote patch.
 * Switch to the new clk_hw_* APIs.
 * Rebase to the current clk-next.

Changes since v1 (https://lkml.org/lkml/2015/6/12/193)
 * Drop SR2 PLL patch, as it is already applied.
 * Add gpll0_vote rate propagation patch.
 * Update/rebase patches to the current clk-next.

Georgi Djakov (3):
  clk: qcom: Add A53 PLL support
  clk: qcom: Add regmap mux-div clocks support
  clk: qcom: Add A53 clock driver

 .../devicetree/bindings/clock/qcom,a53-pll.txt     |   17 ++
 .../devicetree/bindings/clock/qcom,a53cc.txt       |   22 ++
 drivers/clk/qcom/Kconfig                           |   17 ++
 drivers/clk/qcom/Makefile                          |    3 +
 drivers/clk/qcom/a53-pll.c                         |   95 ++++++++
 drivers/clk/qcom/a53cc.c                           |  162 +++++++++++++
 drivers/clk/qcom/clk-regmap-mux-div.c              |  254 ++++++++++++++++++++
 drivers/clk/qcom/clk-regmap-mux-div.h              |   58 +++++
 8 files changed, 628 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/qcom,a53-pll.txt
 create mode 100644 Documentation/devicetree/bindings/clock/qcom,a53cc.txt
 create mode 100644 drivers/clk/qcom/a53-pll.c
 create mode 100644 drivers/clk/qcom/a53cc.c
 create mode 100644 drivers/clk/qcom/clk-regmap-mux-div.c
 create mode 100644 drivers/clk/qcom/clk-regmap-mux-div.h

[PATCH v5 1/3] clk: qcom: Add A53 PLL support

[Georgi Djakov]

Add support for the PLL, which generates the higher range of CPU
frequencies on MSM8916 platforms.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 .../devicetree/bindings/clock/qcom,a53-pll.txt     |   17 ++++
 drivers/clk/qcom/Kconfig                           |    9 ++
 drivers/clk/qcom/Makefile                          |    1 +
 drivers/clk/qcom/a53-pll.c                         |   95 ++++++++++++++++++++
 4 files changed, 122 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/qcom,a53-pll.txt
 create mode 100644 drivers/clk/qcom/a53-pll.c

diff --git a/Documentation/devicetree/bindings/clock/qcom,a53-pll.txt b/Documentation/devicetree/bindings/clock/qcom,a53-pll.txt
new file mode 100644
index 000000000000..50e71e4e13a6
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/qcom,a53-pll.txt
@@ -0,0 +1,17 @@
+A53 PLL Binding
+---------------
+The A53 PLL is the main CPU PLL used for frequencies above 1GHz.
+
+Required properties :
+- compatible : Shall contain only one of the following:
+
+		"qcom,a53-pll"
+
+- reg : shall contain base register location and length
+
+Example:
+
+	a53pll: a53pll@0b016000 {
+		compatible = "qcom,a53-pll";
+		reg = <0x0b016000 0x40>;
+	};
diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
index b552eceec2be..d06cf687be4f 100644
--- a/drivers/clk/qcom/Kconfig
+++ b/drivers/clk/qcom/Kconfig
@@ -123,3 +123,12 @@ config MSM_MMCC_8996
 	  Support for the multimedia clock controller on msm8996 devices.
 	  Say Y if you want to support multimedia devices such as display,
 	  graphics, video encode/decode, camera, etc.
+
+config QCOM_A53PLL
+	bool "A53 PLL"
+	depends on COMMON_CLK_QCOM
+	help
+	  Support for the A53 PLL on some Qualcomm devices. It provides
+	  support for CPU frequencies above 1GHz.
+	  Say Y if you want to support CPU frequency scaling on devices
+	  such as MSM8916.
diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index dc4280b85db1..c7c26eeab67c 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -25,3 +25,4 @@ obj-$(CONFIG_MSM_GCC_8996) += gcc-msm8996.o
 obj-$(CONFIG_MSM_MMCC_8960) += mmcc-msm8960.o
 obj-$(CONFIG_MSM_MMCC_8974) += mmcc-msm8974.o
 obj-$(CONFIG_MSM_MMCC_8996) += mmcc-msm8996.o
+obj-$(CONFIG_QCOM_A53PLL) += a53-pll.o
diff --git a/drivers/clk/qcom/a53-pll.c b/drivers/clk/qcom/a53-pll.c
new file mode 100644
index 000000000000..987bf75f087a
--- /dev/null
+++ b/drivers/clk/qcom/a53-pll.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2016, Linaro Limited. All rights reserved.
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "clk-pll.h"
+#include "clk-regmap.h"
+
+static struct pll_freq_tbl a53pll_freq[] = {
+	{  998400000, 52, 0x0, 0x1, 0 },
+	{ 1094400000, 57, 0x0, 0x1, 0 },
+	{ 1152000000, 62, 0x0, 0x1, 0 },
+	{ 1209600000, 65, 0x0, 0x1, 0 },
+	{ 1401600000, 73, 0x0, 0x1, 0 },
+};
+
+static const struct regmap_config a53pll_regmap_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x40,
+	.fast_io		= true,
+	.val_format_endian	= REGMAP_ENDIAN_LITTLE,
+};
+
+static const struct of_device_id qcom_a53pll_match_table[] = {
+	{ .compatible = "qcom,a53-pll" },
+	{ }
+};
+
+static int qcom_a53pll_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct clk_pll *pll;
+	struct resource *res;
+	void __iomem *base;
+	struct clk *clk;
+	struct regmap *regmap;
+	struct clk_init_data init;
+
+	pll = devm_kzalloc(dev, sizeof(*pll), GFP_KERNEL);
+	if (!pll)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(dev, base, &a53pll_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	pll->l_reg = 0x04,
+	pll->m_reg = 0x08,
+	pll->n_reg = 0x0c,
+	pll->config_reg = 0x14,
+	pll->mode_reg = 0x00,
+	pll->status_reg = 0x1c,
+	pll->status_bit = 16,
+	pll->freq_tbl = a53pll_freq,
+
+	init.name = "a53pll",
+	init.parent_names = (const char *[]){ "xo" },
+	init.num_parents = 1,
+	init.ops = &clk_pll_sr2_ops,
+	pll->clkr.hw.init = &init;
+
+	clk = devm_clk_register_regmap(dev, &pll->clkr);
+
+	return PTR_ERR_OR_ZERO(clk);
+}
+
+static struct platform_driver qcom_a53pll_driver = {
+	.probe = qcom_a53pll_probe,
+	.driver = {
+		.name = "qcom-a53pll",
+		.of_match_table = qcom_a53pll_match_table,
+	},
+};
+
+builtin_platform_driver(qcom_a53pll_driver);

[PATCH v5 2/3] clk: qcom: Add regmap mux-div clocks support

[Georgi Djakov]

Add support for hardware that can switch both parent clocks 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 |  254 +++++++++++++++++++++++++++++++++
 drivers/clk/qcom/clk-regmap-mux-div.h |   58 ++++++++
 3 files changed, 313 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 c7c26eeab67c..bc7637516a6e 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -9,6 +9,7 @@ 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..c69fd0e8e9b7
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap-mux-div.c
@@ -0,0 +1,254 @@
+/*
+ * Copyright (c) 2016, Linaro Limited. All rights reserved.
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/delay.h>
+#include <linux/export.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, __div, __src;
+	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);
+	__src = (val >> md->src_shift);
+	__src &= BIT(md->src_width) - 1;
+	*src = __src;
+
+	__div = (val >> md->hid_shift);
+	__div &= BIT(md->hid_width) - 1;
+	*div = __div;
+}
+
+static int mux_div_enable(struct clk_hw *hw)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+
+	return __mux_div_set_src_div(md, md->src, md->div);
+}
+
+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;
+}
+
+static void mux_div_disable(struct clk_hw *hw)
+{
+	struct clk_regmap_mux_div *md = to_clk_regmap_mux_div(hw);
+
+	__mux_div_set_src_div(md, md->safe_src, md->safe_div);
+}
+
+const struct clk_ops clk_regmap_mux_div_ops = {
+	.enable = mux_div_enable,
+	.disable = mux_div_disable,
+	.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..d63a06575de9
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap-mux-div.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2016, Linaro Limited. All rights reserved.
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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 __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
+ * @safe_src:	the safe source mux value we switch to, while the main PLL is
+ *		reconfigured
+ * @safe_div:	the safe divider value that we set, while the main PLL is
+ *		reconfigured
+ * @parent_map:	pointer to parent_map struct
+ * @clkr:	handle between common and hardware-specific interfaces
+ * @clk_nb:	clock notifier registered for clock rate changes of the A53 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;
+	u32				safe_src;
+	u32				safe_div;
+	const struct parent_map		*parent_map;
+	struct clk_regmap		clkr;
+	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

[PATCH v5 3/3] clk: qcom: Add A53 clock driver

[Georgi Djakov]

Add a driver for the A53 Clock Controller. It is a hardware block that
implements a combined mux and half integer divider functionality. It can
choose between a fixed-rate clock or the dedicated A53 PLL. The source
and the divider can be set both at the same time.

This is required for enabling CPU frequency scaling on platforms such as
MSM8916.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 .../devicetree/bindings/clock/qcom,a53cc.txt       |   22 +++
 drivers/clk/qcom/Kconfig                           |    8 +
 drivers/clk/qcom/Makefile                          |    1 +
 drivers/clk/qcom/a53cc.c                           |  162 ++++++++++++++++++++
 4 files changed, 193 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/qcom,a53cc.txt
 create mode 100644 drivers/clk/qcom/a53cc.c

diff --git a/Documentation/devicetree/bindings/clock/qcom,a53cc.txt b/Documentation/devicetree/bindings/clock/qcom,a53cc.txt
new file mode 100644
index 000000000000..a025f062f177
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/qcom,a53cc.txt
@@ -0,0 +1,22 @@
+Qualcomm A53 CPU Clock Controller Binding
+------------------------------------------------
+The A53 CPU Clock Controller is hardware, which provides a combined
+mux and divider functionality for the CPU clocks. It can choose between
+a fixed rate clock and the dedicated A53 PLL.
+
+Required properties :
+- compatible : shall contain:
+
+			"qcom,a53cc"
+
+- reg : shall contain base register location and length
+	of the APCS region
+- #clock-cells : shall contain 1
+
+Example:
+
+	apcs: syscon@b011000 {
+		compatible = "qcom,a53cc", "syscon";
+		reg = <0x0b011000 0x1000>;
+		#clock-cells = <1>;
+	};
diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
index d06cf687be4f..27a1622ca891 100644
--- a/drivers/clk/qcom/Kconfig
+++ b/drivers/clk/qcom/Kconfig
@@ -132,3 +132,11 @@ config QCOM_A53PLL
 	  support for CPU frequencies above 1GHz.
 	  Say Y if you want to support CPU frequency scaling on devices
 	  such as MSM8916.
+
+config QCOM_A53CC
+	bool "A53 Clock Controller"
+	depends on COMMON_CLK_QCOM && QCOM_A53PLL
+	help
+	  Support for the A53 clock controller on some Qualcomm devices.
+	  Say Y if you want to support CPU frequency scaling on devices
+	  such as MSM8916.
diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index bc7637516a6e..9a67697b9540 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -26,4 +26,5 @@ obj-$(CONFIG_MSM_GCC_8996) += gcc-msm8996.o
 obj-$(CONFIG_MSM_MMCC_8960) += mmcc-msm8960.o
 obj-$(CONFIG_MSM_MMCC_8974) += mmcc-msm8974.o
 obj-$(CONFIG_MSM_MMCC_8996) += mmcc-msm8996.o
+obj-$(CONFIG_QCOM_A53CC) += a53cc.o
 obj-$(CONFIG_QCOM_A53PLL) += a53-pll.o
diff --git a/drivers/clk/qcom/a53cc.c b/drivers/clk/qcom/a53cc.c
new file mode 100644
index 000000000000..74b462893045
--- /dev/null
+++ b/drivers/clk/qcom/a53cc.c
@@ -0,0 +1,162 @@
+/*
+ * Copyright (c) 2016, Linaro Limited. All rights reserved.
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/cpu.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "clk-regmap.h"
+#include "clk-regmap-mux-div.h"
+
+enum {
+	P_GPLL0,
+	P_A53PLL,
+};
+
+static const struct parent_map gpll0_a53cc_map[] = {
+	{ P_GPLL0, 4 },
+	{ P_A53PLL, 5 },
+};
+
+static const char * const gpll0_a53cc[] = {
+	"gpll0_vote",
+	"a53pll",
+};
+
+static const struct regmap_config a53cc_regmap_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x1000,
+	.fast_io		= true,
+	.val_format_endian	= REGMAP_ENDIAN_LITTLE,
+};
+
+static const struct of_device_id qcom_a53cc_match_table[] = {
+	{ .compatible = "qcom,a53cc" },
+	{ }
+};
+
+/*
+ * We use the notifier function for switching to a temporary safe configuration
+ * (mux and divider), while the a53 pll is reconfigured.
+ */
+static int a53cc_notifier_cb(struct notifier_block *nb, unsigned long event,
+			     void *data)
+{
+	int ret = 0;
+	struct clk_regmap_mux_div *md = container_of(nb,
+						     struct clk_regmap_mux_div,
+						     clk_nb);
+
+	if (event == PRE_RATE_CHANGE)
+		ret = __mux_div_set_src_div(md, md->safe_src, md->safe_div);
+
+	return notifier_from_errno(ret);
+}
+
+static int qcom_a53cc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct clk_regmap_mux_div *a53cc;
+	struct resource *res;
+	void __iomem *base;
+	struct clk *clk, *pclk;
+	struct regmap *regmap;
+	struct clk_init_data init;
+	int ret;
+
+	a53cc = devm_kzalloc(dev, sizeof(*a53cc), GFP_KERNEL);
+	if (!a53cc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	a53cc->reg_offset = 0x50,
+	a53cc->hid_width = 5,
+	a53cc->hid_shift = 0,
+	a53cc->src_width = 3,
+	a53cc->src_shift = 8,
+	a53cc->safe_src = 4,
+	a53cc->safe_div = 3,
+	a53cc->parent_map = gpll0_a53cc_map,
+
+	init.name = "a53mux",
+	init.parent_names = gpll0_a53cc,
+	init.num_parents = 2,
+	init.ops = &clk_regmap_mux_div_ops,
+	init.flags = CLK_SET_RATE_PARENT;
+	a53cc->clkr.hw.init = &init;
+
+	pclk = __clk_lookup(gpll0_a53cc[1]);
+	if (!pclk)
+		return -EPROBE_DEFER;
+
+	/* activate A53 PLL output */
+	ret = clk_prepare_enable(pclk);
+	if (ret) {
+		dev_err(dev, "failed to enable %s: %d\n", gpll0_a53cc[1], ret);
+		return ret;
+	}
+
+	a53cc->clk_nb.notifier_call = a53cc_notifier_cb;
+	ret = clk_notifier_register(pclk, &a53cc->clk_nb);
+	if (ret) {
+		dev_err(dev, "failed to register clock notifier: %d\n", ret);
+		return ret;
+	}
+
+	regmap = devm_regmap_init_mmio(dev, base, &a53cc_regmap_config);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "failed to init regmap mmio: %d\n", ret);
+		goto err;
+	}
+
+	a53cc->clkr.regmap = regmap;
+
+	clk = devm_clk_register_regmap(dev, &a53cc->clkr);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(dev, "failed to register regmap clock: %d\n", ret);
+		goto err;
+	}
+
+	ret = of_clk_add_provider(dev->of_node, of_clk_src_simple_get, clk);
+	if (ret) {
+		dev_err(dev, "failed to add clock provider: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+err:
+	clk_notifier_unregister(pclk, &a53cc->clk_nb);
+	return ret;
+}
+
+static struct platform_driver qcom_a53cc_driver = {
+	.probe = qcom_a53cc_probe,
+	.driver = {
+		.name = "qcom-a53cc",
+		.of_match_table = qcom_a53cc_match_table,
+	},
+};
+
+builtin_platform_driver(qcom_a53cc_driver);