[PATCH V1] clk: qcom: Add qpnp clock divider support

[Tirupathi Reddy]

Clkdiv module provides a clock output on the PMIC with CXO as
the source. This clock can be routed through PMIC GPIOs. Add
a device driver to configure this clkdiv module.

Signed-off-by: Tirupathi Reddy <tirupath@xxxxxxxxxxxxxx>
---
 .../devicetree/bindings/clock/clk-qpnp-div.txt     |  52 +++
 drivers/clk/qcom/Kconfig                           |   9 +
 drivers/clk/qcom/Makefile                          |   1 +
 drivers/clk/qcom/clk-qpnp-div.c                    | 422 +++++++++++++++++++++
 4 files changed, 484 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/clk-qpnp-div.txt
 create mode 100644 drivers/clk/qcom/clk-qpnp-div.c

diff --git a/Documentation/devicetree/bindings/clock/clk-qpnp-div.txt b/Documentation/devicetree/bindings/clock/clk-qpnp-div.txt
new file mode 100644
index 0000000..03b7b70
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/clk-qpnp-div.txt
@@ -0,0 +1,52 @@
+Qualcomm Technologies, Inc. QPNP clock divider (clkdiv)
+
+clkdiv configures the clock frequency of a set of outputs on the PMIC.
+These clocks are typically wired through alternate functions on
+gpio pins.
+
+=======================
+Supported Properties
+=======================
+
+- compatible
+	Usage:      required
+	Value type: <string>
+	Definition: should be "qcom,qpnp-clkdiv".
+
+- reg
+	Usage:      required
+	Value type: <prop-encoded-array>
+	Definition: Addresses and sizes for the memory of this CLKDIV
+		    peripheral.
+
+- qcom,cxo-freq
+	Usage:      required
+	Value type: <u32>
+	Definition: The frequency of the crystal oscillator (CXO) clock in Hz.
+
+- qcom,clkdiv-id
+	Usage:      required
+	Value type: <u32>
+	Definition: Integer value specifies the hardware identifier of this
+		    CLKDIV peripheral.
+
+- qcom,clkdiv-init-freq
+	Usage:      optional
+	Value type: <u32>
+	Definition: Initial output frequency in Hz to configure for the CLKDIV
+		    peripheral. The initial frequency value should be less than
+		    or equal to CXO clock frequency and greater than or equal to
+		    CXO_freq/64.
+
+=======
+Example
+=======
+
+qcom,clkdiv@5b00 {
+	compatible = "qcom,qpnp-clkdiv";
+	reg = <0x5b00 0x100>;
+
+	qcom,cxo-freq = <19200000>;
+	qcom,clkdiv-id = <1>;
+	qcom,clkdiv-init-freq = <9600000>;
+};
diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
index 9f6c278..c68ae96 100644
--- a/drivers/clk/qcom/Kconfig
+++ b/drivers/clk/qcom/Kconfig
@@ -196,3 +196,12 @@ 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 CLOCK_QPNP_DIV
+	tristate "QPNP PMIC clkdiv driver"
+	depends on COMMON_CLK_QCOM && SPMI
+	help
+	  This driver supports the clkdiv functionality on the Qualcomm
+	  Technologies, Inc. QPNP PMIC. It configures the frequency of
+	  clkdiv outputs on the PMIC. These clocks are typically wired
+	  through alternate functions on gpio pins.
diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index 3f3aff2..cca8840 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_MSM_MMCC_8974) += mmcc-msm8974.o
 obj-$(CONFIG_MSM_MMCC_8996) += mmcc-msm8996.o
 obj-$(CONFIG_QCOM_CLK_RPM) += clk-rpm.o
 obj-$(CONFIG_QCOM_CLK_SMD_RPM) += clk-smd-rpm.o
+obj-$(CONFIG_CLOCK_QPNP_DIV) += clk-qpnp-div.o
diff --git a/drivers/clk/qcom/clk-qpnp-div.c b/drivers/clk/qcom/clk-qpnp-div.c
new file mode 100644
index 0000000..416c20f
--- /dev/null
+++ b/drivers/clk/qcom/clk-qpnp-div.c
@@ -0,0 +1,422 @@
+/* Copyright (c) 2017, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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/delay.h>
+#include <linux/err.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#define Q_REG_DIV_CTL1			0x43
+#define Q_DIV_CTL1_DIV_FACTOR_MASK	GENMASK(2, 0)
+
+#define Q_REG_EN_CTL			0x46
+#define Q_REG_EN_MASK			BIT(7)
+#define Q_SET_EN			BIT(7)
+
+#define Q_CXO_PERIOD_NS(cxo_clk)	(NSEC_PER_SEC / cxo_clk)
+#define Q_DIV_PERIOD_NS(cxo_clk, div)	(NSEC_PER_SEC / (cxo_clk / div))
+#define Q_ENABLE_DELAY_NS(cxo_clk, div)	(2 * Q_CXO_PERIOD_NS(cxo_clk) + \
+					(3 * Q_DIV_PERIOD_NS(cxo_clk, div)))
+#define Q_DISABLE_DELAY_NS(cxo_clk, div) \
+					(3 * Q_DIV_PERIOD_NS(cxo_clk, div))
+
+#define CLK_QPNP_DIV_OFFSET		1
+
+enum q_clk_div_factor {
+	Q_CLKDIV_XO_DIV_1_0 = 0,
+	Q_CLKDIV_XO_DIV_1,
+	Q_CLKDIV_XO_DIV_2,
+	Q_CLKDIV_XO_DIV_4,
+	Q_CLKDIV_XO_DIV_8,
+	Q_CLKDIV_XO_DIV_16,
+	Q_CLKDIV_XO_DIV_32,
+	Q_CLKDIV_XO_DIV_64,
+	Q_CLKDIV_MAX_ALLOWED,
+};
+
+enum q_clkdiv_state {
+	DISABLE = false,
+	ENABLE = true,
+};
+
+struct q_clkdiv {
+	struct regmap		*regmap;
+	struct device		*dev;
+
+	u16			base;
+	spinlock_t		lock;
+
+	/* clock properties */
+	struct clk_hw		hw;
+	unsigned int		cxo_hz;
+	enum q_clk_div_factor	div_factor;
+	bool			enabled;
+};
+
+static inline struct q_clkdiv *to_clkdiv(struct clk_hw *_hw)
+{
+	return container_of(_hw, struct q_clkdiv, hw);
+}
+
+static inline unsigned int div_factor_to_div(unsigned int div_factor)
+{
+	if (div_factor == Q_CLKDIV_XO_DIV_1_0)
+		return 1;
+
+	return 1 << (div_factor - CLK_QPNP_DIV_OFFSET);
+}
+
+static inline unsigned int div_to_div_factor(unsigned int div)
+{
+	return ilog2(div) + CLK_QPNP_DIV_OFFSET;
+}
+
+static int qpnp_clkdiv_masked_write(struct q_clkdiv *q_clkdiv, u16 offset,
+			u8 mask, u8 val)
+{
+	int rc;
+
+	rc = regmap_update_bits(q_clkdiv->regmap, q_clkdiv->base + offset, mask,
+				val);
+	if (rc)
+		dev_err(q_clkdiv->dev,
+			"Unable to regmap_update_bits to addr=%hx, rc(%d)\n",
+			q_clkdiv->base + offset, rc);
+
+	return rc;
+}
+
+static int qpnp_clkdiv_set_enable_state(struct q_clkdiv *q_clkdiv,
+			enum q_clkdiv_state enable_state)
+{
+	int rc;
+
+	rc = qpnp_clkdiv_masked_write(q_clkdiv, Q_REG_EN_CTL, Q_REG_EN_MASK,
+				(enable_state == ENABLE) ? Q_SET_EN : 0);
+	if (rc)
+		return rc;
+
+	if (enable_state == ENABLE)
+		ndelay(Q_ENABLE_DELAY_NS(q_clkdiv->cxo_hz,
+				div_factor_to_div(q_clkdiv->div_factor)));
+	else
+		ndelay(Q_DISABLE_DELAY_NS(q_clkdiv->cxo_hz,
+				div_factor_to_div(q_clkdiv->div_factor)));
+
+	return rc;
+}
+
+static int qpnp_clkdiv_config_freq_div(struct q_clkdiv *q_clkdiv,
+			unsigned int div)
+{
+	unsigned int div_factor;
+	int rc;
+
+	div_factor = div_to_div_factor(div);
+	if (div_factor <= 0 || div_factor >= Q_CLKDIV_MAX_ALLOWED)
+		return -EINVAL;
+
+	if (q_clkdiv->enabled) {
+		rc = qpnp_clkdiv_set_enable_state(q_clkdiv, DISABLE);
+		if (rc) {
+			dev_err(q_clkdiv->dev, "unable to disable clock, rc = %d\n",
+				rc);
+			return rc;
+		}
+	}
+
+	rc = qpnp_clkdiv_masked_write(q_clkdiv, Q_REG_DIV_CTL1,
+				Q_DIV_CTL1_DIV_FACTOR_MASK, div_factor);
+	if (rc) {
+		dev_err(q_clkdiv->dev, "config divider failed, rc=%d\n",
+			rc);
+		return rc;
+	}
+
+	q_clkdiv->div_factor = div_factor;
+
+	if (q_clkdiv->enabled) {
+		rc = qpnp_clkdiv_set_enable_state(q_clkdiv, ENABLE);
+		if (rc)
+			dev_err(q_clkdiv->dev, "unable to re-enable clock, rc = %d\n",
+				rc);
+	}
+
+	return rc;
+}
+
+static int clk_qpnp_div_enable(struct clk_hw *hw)
+{
+	struct q_clkdiv *q_clkdiv = to_clkdiv(hw);
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&q_clkdiv->lock, flags);
+
+	rc =  qpnp_clkdiv_set_enable_state(q_clkdiv, ENABLE);
+	if (rc) {
+		dev_err(q_clkdiv->dev, "clk enable failed, rc=%d\n", rc);
+		goto fail;
+	}
+
+	q_clkdiv->enabled = true;
+
+fail:
+	spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+	return rc;
+}
+
+static void clk_qpnp_div_disable(struct clk_hw *hw)
+{
+	struct q_clkdiv *q_clkdiv = to_clkdiv(hw);
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&q_clkdiv->lock, flags);
+
+	rc = qpnp_clkdiv_set_enable_state(q_clkdiv, DISABLE);
+	if (rc) {
+		dev_err(q_clkdiv->dev, "clk disable failed, rc=%d\n", rc);
+		goto fail;
+	}
+
+	q_clkdiv->enabled = false;
+
+fail:
+	spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+}
+
+static long clk_qpnp_div_round_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long *parent_rate)
+{
+	struct q_clkdiv *q_clkdiv = to_clkdiv(hw);
+	unsigned long flags, new_rate;
+	unsigned int div, div_factor;
+
+	spin_lock_irqsave(&q_clkdiv->lock, flags);
+	if (rate <= 0 || rate > q_clkdiv->cxo_hz) {
+		dev_err(q_clkdiv->dev, "invalid rate requested, rate = %lu\n",
+			rate);
+		spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+		return -EINVAL;
+	}
+
+	div = DIV_ROUND_UP(q_clkdiv->cxo_hz, rate);
+	div_factor = div_to_div_factor(div);
+	if (div_factor >= Q_CLKDIV_MAX_ALLOWED)
+		div_factor = Q_CLKDIV_MAX_ALLOWED - 1;
+	new_rate = q_clkdiv->cxo_hz / div_factor_to_div(div_factor);
+
+	spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+	return new_rate;
+}
+
+static unsigned long clk_qpnp_div_recalc_rate(struct clk_hw *hw,
+			unsigned long parent_rate)
+{
+	struct q_clkdiv *q_clkdiv = to_clkdiv(hw);
+	unsigned long rate, flags;
+
+	spin_lock_irqsave(&q_clkdiv->lock, flags);
+
+	rate = q_clkdiv->cxo_hz / div_factor_to_div(q_clkdiv->div_factor);
+
+	spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+	return rate;
+}
+
+static int clk_qpnp_div_set_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long parent_rate)
+{
+	struct q_clkdiv *q_clkdiv = to_clkdiv(hw);
+	unsigned long flags;
+	int rc = 0;
+
+	spin_lock_irqsave(&q_clkdiv->lock, flags);
+	if (rate <= 0 || rate > q_clkdiv->cxo_hz) {
+		dev_err(q_clkdiv->dev, "invalid rate requested, rate = %lu\n",
+			rate);
+		rc = -EINVAL;
+		goto fail;
+	}
+
+	rc = qpnp_clkdiv_config_freq_div(q_clkdiv, q_clkdiv->cxo_hz / rate);
+	if (rc)
+		dev_err(q_clkdiv->dev, "clkdiv set rate(%lu) failed, rc = %d\n",
+			rate, rc);
+
+fail:
+	spin_unlock_irqrestore(&q_clkdiv->lock, flags);
+	return rc;
+}
+
+const struct clk_ops clk_qpnp_div_ops = {
+	.enable = clk_qpnp_div_enable,
+	.disable = clk_qpnp_div_disable,
+	.set_rate = clk_qpnp_div_set_rate,
+	.recalc_rate = clk_qpnp_div_recalc_rate,
+	.round_rate = clk_qpnp_div_round_rate,
+};
+
+#define QPNP_CLKDIV_MAX_NAME_LEN	16
+
+static int qpnp_clkdiv_probe(struct platform_device *pdev)
+{
+	struct q_clkdiv *q_clkdiv;
+	struct device *dev = &pdev->dev;
+	struct device_node *of_node = dev->of_node;
+	struct clk_init_data *init;
+	struct clk_onecell_data *clk_data;
+	struct clk *clk;
+	unsigned int base, div, init_freq;
+	int rc = 0, id;
+	char *clk_name;
+
+	q_clkdiv = devm_kzalloc(dev, sizeof(*q_clkdiv), GFP_KERNEL);
+	if (!q_clkdiv)
+		return -ENOMEM;
+
+	q_clkdiv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!q_clkdiv->regmap) {
+		dev_err(dev, "Couldn't get parent's regmap\n");
+		return -EINVAL;
+	}
+	q_clkdiv->dev = dev;
+
+	rc = of_property_read_u32(of_node, "reg", &base);
+	if (rc < 0) {
+		dev_err(dev, "Couldn't find reg in node = %s, rc = %d\n",
+			of_node->full_name, rc);
+		return rc;
+	}
+	q_clkdiv->base = base;
+
+	/* init clock properties */
+	rc = of_property_read_u32(of_node, "qcom,cxo-freq", &q_clkdiv->cxo_hz);
+	if (rc) {
+		dev_err(dev, "unable to get qcom,cxo-freq property, rc = %d\n",
+			rc);
+		return rc;
+	}
+
+	q_clkdiv->div_factor = Q_CLKDIV_XO_DIV_1_0;
+	rc = of_property_read_u32(of_node, "qcom,clkdiv-init-freq", &init_freq);
+	if (rc) {
+		if (rc != -EINVAL) {
+			dev_err(dev, "Unable to read initial frequency value, rc=%d\n",
+				rc);
+			return rc;
+		}
+	} else {
+		if (init_freq <= 0 || init_freq > q_clkdiv->cxo_hz) {
+			dev_err(dev, "invalid initial frequency specified, rate = %u\n",
+				init_freq);
+			return -EINVAL;
+		}
+
+		div = DIV_ROUND_UP(q_clkdiv->cxo_hz, init_freq);
+		q_clkdiv->div_factor = div_to_div_factor(div);
+		if (q_clkdiv->div_factor >= Q_CLKDIV_MAX_ALLOWED)
+			q_clkdiv->div_factor = Q_CLKDIV_MAX_ALLOWED - 1;
+		rc = qpnp_clkdiv_config_freq_div(q_clkdiv,
+				div_factor_to_div(q_clkdiv->div_factor));
+		if (rc) {
+			dev_err(dev, "Config initial frequency failed, rc = %d\n",
+				rc);
+			return rc;
+		}
+	}
+
+	init = devm_kzalloc(dev, sizeof(*init), GFP_KERNEL);
+	if (!init)
+		return -ENOMEM;
+
+	rc = of_property_read_u32(of_node, "qcom,clkdiv-id", &id);
+	if (rc) {
+		dev_err(dev, "Unable to read clkdiv node id, rc = %d\n", rc);
+		return rc;
+	}
+
+	clk_name = devm_kcalloc(dev, QPNP_CLKDIV_MAX_NAME_LEN,
+				sizeof(*clk_name), GFP_KERNEL);
+	if (!clk_name)
+		return -ENOMEM;
+	snprintf(clk_name, QPNP_CLKDIV_MAX_NAME_LEN, "qpnp_clkdiv_%d", id);
+
+	init->name = clk_name;
+	init->ops = &clk_qpnp_div_ops;
+	q_clkdiv->hw.init = init;
+	spin_lock_init(&q_clkdiv->lock);
+
+	clk_data = devm_kzalloc(dev, sizeof(*clk_data), GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->clks = devm_kzalloc(dev, sizeof(*clk_data->clks), GFP_KERNEL);
+	if (!clk_data->clks)
+		return -ENOMEM;
+
+	clk = devm_clk_register(dev, &q_clkdiv->hw);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "Unable to register qpnp div clock\n");
+		return PTR_ERR(clk);
+	}
+
+	clk_data->clk_num = 1;
+	clk_data->clks[0] = clk;
+
+	rc = of_clk_add_provider(of_node, of_clk_src_onecell_get, clk_data);
+	if (rc) {
+		dev_err(dev, "Unable to register qpnp div clock provider, rc = %d\n",
+			rc);
+		return rc;
+	}
+
+	dev_set_drvdata(dev, q_clkdiv);
+	dev_info(dev, "Registered %s successfully\n", clk_name);
+
+	return rc;
+}
+
+static const struct of_device_id qpnp_clkdiv_match_table[] = {
+	{ .compatible = "qcom,qpnp-clkdiv" },
+	{}
+};
+
+static struct platform_driver qpnp_clkdiv_driver = {
+	.driver		= {
+		.name	= "qcom,qpnp-clkdiv",
+		.of_match_table = qpnp_clkdiv_match_table,
+	},
+	.probe		= qpnp_clkdiv_probe,
+};
+
+static int __init qpnp_clkdiv_init(void)
+{
+	return platform_driver_register(&qpnp_clkdiv_driver);
+}
+module_init(qpnp_clkdiv_init);
+
+static void __exit qpnp_clkdiv_exit(void)
+{
+	return platform_driver_unregister(&qpnp_clkdiv_driver);
+}
+module_exit(qpnp_clkdiv_exit);
+
+MODULE_DESCRIPTION("QPNP PMIC clkdiv driver");
+MODULE_LICENSE("GPL v2");
-- 
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