clk: add CS2000 Fractional-N driver

This patch adds CS2000 Fractional-N driver as clock provider.

Signed-off-by: Kuninori Morimoto <[e-mail]>
[[e-mail]: Fix unsigned checked for < 0 in
cs2000_ratio_get()]
Signed-off-by: Stephen Boyd <[e-mail]>

Documentation/devicetree/bindings/clock/cs2000-cp.txt

···
+CIRRUS LOGIC Fractional-N Clock Synthesizer & Clock Multiplier
+
+Required properties:
+
+- compatible:		"cirrus,cs2000-cp"
+- reg:			The chip select number on the I2C bus
+- clocks:		common clock binding for CLK_IN, XTI/REF_CLK
+- clock-names:		CLK_IN : clk_in, XTI/REF_CLK : ref_clk
+- #clock-cells:		must be <0>
+
+Example:
+
+&i2c2 {
+	...
+	cs2000: clk_multiplier@4f {
+		#clock-cells = <0>;
+		compatible = "cirrus,cs2000-cp";
+		reg = <0x4f>;
+		clocks = <&rcar_sound 0>, <&x12_clk>;
+		clock-names = "clk_in", "ref_clk";
+	};
+};

drivers/clk/Kconfig

···
 	  Given a target output frequency, the driver will set the PLL and
 	  divider to best approximate the desired output.
 
+config COMMON_CLK_CS2000_CP
+	tristate "Clock driver for CS2000 Fractional-N Clock Synthesizer & Clock Multiplier"
+	depends on I2C
+	help
+	  If you say yes here you get support for the CS2000 clock multiplier.
+
 config COMMON_CLK_S2MPS11
 	tristate "Clock driver for S2MPS1X/S5M8767 MFD"
 	depends on MFD_SEC_CORE

drivers/clk/Makefile

···
 obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN)	+= clk-axi-clkgen.o
 obj-$(CONFIG_ARCH_AXXIA)		+= clk-axm5516.o
 obj-$(CONFIG_COMMON_CLK_CDCE706)	+= clk-cdce706.o
+obj-$(CONFIG_COMMON_CLK_CS2000_CP)	+= clk-cs2000-cp.o
 obj-$(CONFIG_ARCH_CLPS711X)		+= clk-clps711x.o
 obj-$(CONFIG_ARCH_EFM32)		+= clk-efm32gg.o
 obj-$(CONFIG_ARCH_HIGHBANK)		+= clk-highbank.o

drivers/clk/clk-cs2000-cp.c

···
+/*
+ * CS2000  --  CIRRUS LOGIC Fractional-N Clock Synthesizer & Clock Multiplier
+ *
+ * Copyright (C) 2015 Renesas Electronics Corporation
+ * Kuninori Morimoto <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/of_device.h>
+#include <linux/module.h>
+
+#define CH_MAX 4
+#define RATIO_REG_SIZE 4
+
+#define DEVICE_ID	0x1
+#define DEVICE_CTRL	0x2
+#define DEVICE_CFG1	0x3
+#define DEVICE_CFG2	0x4
+#define GLOBAL_CFG	0x5
+#define Ratio_Add(x, nth)	(6 + (x * 4) + (nth))
+#define Ratio_Val(x, nth)	((x >> (24 - (8 * nth))) & 0xFF)
+#define Val_Ratio(x, nth)	((x & 0xFF) << (24 - (8 * nth)))
+#define FUNC_CFG1	0x16
+#define FUNC_CFG2	0x17
+
+/* DEVICE_ID */
+#define REVISION_MASK	(0x7)
+#define REVISION_B2_B3	(0x4)
+#define REVISION_C1	(0x6)
+
+/* DEVICE_CTRL */
+#define PLL_UNLOCK	(1 << 7)
+
+/* DEVICE_CFG1 */
+#define RSEL(x)		(((x) & 0x3) << 3)
+#define RSEL_MASK	RSEL(0x3)
+#define ENDEV1		(0x1)
+
+/* GLOBAL_CFG */
+#define ENDEV2		(0x1)
+
+#define CH_SIZE_ERR(ch)		((ch < 0) || (ch >= CH_MAX))
+#define hw_to_priv(_hw)		container_of(_hw, struct cs2000_priv, hw)
+#define priv_to_client(priv)	(priv->client)
+#define priv_to_dev(priv)	(&(priv_to_client(priv)->dev))
+
+#define CLK_IN	0
+#define REF_CLK	1
+#define CLK_MAX 2
+
+struct cs2000_priv {
+	struct clk_hw hw;
+	struct i2c_client *client;
+	struct clk *clk_in;
+	struct clk *ref_clk;
+	struct clk *clk_out;
+};
+
+static const struct of_device_id cs2000_of_match[] = {
+	{ .compatible = "cirrus,cs2000-cp", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cs2000_of_match);
+
+static const struct i2c_device_id cs2000_id[] = {
+	{ "cs2000-cp", },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, cs2000_id);
+
+#define cs2000_read(priv, addr) \
+	i2c_smbus_read_byte_data(priv_to_client(priv), addr)
+#define cs2000_write(priv, addr, val) \
+	i2c_smbus_write_byte_data(priv_to_client(priv), addr, val)
+
+static int cs2000_bset(struct cs2000_priv *priv, u8 addr, u8 mask, u8 val)
+{
+	s32 data;
+
+	data = cs2000_read(priv, addr);
+	if (data < 0)
+		return data;
+
+	data &= ~mask;
+	data |= (val & mask);
+
+	return cs2000_write(priv, addr, data);
+}
+
+static int cs2000_enable_dev_config(struct cs2000_priv *priv, bool enable)
+{
+	int ret;
+
+	ret = cs2000_bset(priv, DEVICE_CFG1, ENDEV1,
+			  enable ? ENDEV1 : 0);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_bset(priv, GLOBAL_CFG,  ENDEV2,
+			  enable ? ENDEV2 : 0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int cs2000_clk_in_bound_rate(struct cs2000_priv *priv,
+				    u32 rate_in)
+{
+	u32 val;
+
+	if (rate_in >= 32000000 && rate_in < 56000000)
+		val = 0x0;
+	else if (rate_in >= 16000000 && rate_in < 28000000)
+		val = 0x1;
+	else if (rate_in >= 8000000 && rate_in < 14000000)
+		val = 0x2;
+	else
+		return -EINVAL;
+
+	return cs2000_bset(priv, FUNC_CFG1, 0x3 << 3, val << 3);
+}
+
+static int cs2000_wait_pll_lock(struct cs2000_priv *priv)
+{
+	struct device *dev = priv_to_dev(priv);
+	s32 val;
+	unsigned int i;
+
+	for (i = 0; i < 256; i++) {
+		val = cs2000_read(priv, DEVICE_CTRL);
+		if (val < 0)
+			return val;
+		if (!(val & PLL_UNLOCK))
+			return 0;
+		udelay(1);
+	}
+
+	dev_err(dev, "pll lock failed\n");
+
+	return -ETIMEDOUT;
+}
+
+static int cs2000_clk_out_enable(struct cs2000_priv *priv, bool enable)
+{
+	/* enable both AUX_OUT, CLK_OUT */
+	return cs2000_write(priv, DEVICE_CTRL, enable ? 0 : 0x3);
+}
+
+static u32 cs2000_rate_to_ratio(u32 rate_in, u32 rate_out)
+{
+	u64 ratio;
+
+	/*
+	 * ratio = rate_out / rate_in * 2^20
+	 *
+	 * To avoid over flow, rate_out is u64.
+	 * The result should be u32.
+	 */
+	ratio = (u64)rate_out << 20;
+	do_div(ratio, rate_in);
+
+	return ratio;
+}
+
+static unsigned long cs2000_ratio_to_rate(u32 ratio, u32 rate_in)
+{
+	u64 rate_out;
+
+	/*
+	 * ratio = rate_out / rate_in * 2^20
+	 *
+	 * To avoid over flow, rate_out is u64.
+	 * The result should be u32 or unsigned long.
+	 */
+
+	rate_out = (u64)ratio * rate_in;
+	return rate_out >> 20;
+}
+
+static int cs2000_ratio_set(struct cs2000_priv *priv,
+			    int ch, u32 rate_in, u32 rate_out)
+{
+	u32 val;
+	unsigned int i;
+	int ret;
+
+	if (CH_SIZE_ERR(ch))
+		return -EINVAL;
+
+	val = cs2000_rate_to_ratio(rate_in, rate_out);
+	for (i = 0; i < RATIO_REG_SIZE; i++) {
+		ret = cs2000_write(priv,
+				   Ratio_Add(ch, i),
+				   Ratio_Val(val, i));
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static u32 cs2000_ratio_get(struct cs2000_priv *priv, int ch)
+{
+	s32 tmp;
+	u32 val;
+	unsigned int i;
+
+	val = 0;
+	for (i = 0; i < RATIO_REG_SIZE; i++) {
+		tmp = cs2000_read(priv, Ratio_Add(ch, i));
+		if (tmp < 0)
+			return 0;
+
+		val |= Val_Ratio(tmp, i);
+	}
+
+	return val;
+}
+
+static int cs2000_ratio_select(struct cs2000_priv *priv, int ch)
+{
+	int ret;
+
+	if (CH_SIZE_ERR(ch))
+		return -EINVAL;
+
+	/*
+	 * FIXME
+	 *
+	 * this driver supports static ratio mode only at this point.
+	 */
+	ret = cs2000_bset(priv, DEVICE_CFG1, RSEL_MASK, RSEL(ch));
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_write(priv, DEVICE_CFG2, 0x0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static unsigned long cs2000_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct cs2000_priv *priv = hw_to_priv(hw);
+	int ch = 0; /* it uses ch0 only at this point */
+	u32 ratio;
+
+	ratio = cs2000_ratio_get(priv, ch);
+
+	return cs2000_ratio_to_rate(ratio, parent_rate);
+}
+
+static long cs2000_round_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long *parent_rate)
+{
+	u32 ratio;
+
+	ratio = cs2000_rate_to_ratio(*parent_rate, rate);
+
+	return cs2000_ratio_to_rate(ratio, *parent_rate);
+}
+
+static int __cs2000_set_rate(struct cs2000_priv *priv, int ch,
+			     unsigned long rate, unsigned long parent_rate)
+
+{
+	int ret;
+
+	ret = cs2000_clk_in_bound_rate(priv, parent_rate);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_ratio_set(priv, ch, parent_rate, rate);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_ratio_select(priv, ch);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int cs2000_set_rate(struct clk_hw *hw,
+			   unsigned long rate, unsigned long parent_rate)
+{
+	struct cs2000_priv *priv = hw_to_priv(hw);
+	int ch = 0; /* it uses ch0 only at this point */
+
+	return __cs2000_set_rate(priv, ch, rate, parent_rate);
+}
+
+static int cs2000_enable(struct clk_hw *hw)
+{
+	struct cs2000_priv *priv = hw_to_priv(hw);
+	int ret;
+
+	ret = cs2000_enable_dev_config(priv, true);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_clk_out_enable(priv, true);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_wait_pll_lock(priv);
+	if (ret < 0)
+		return ret;
+
+	return ret;
+}
+
+static void cs2000_disable(struct clk_hw *hw)
+{
+	struct cs2000_priv *priv = hw_to_priv(hw);
+
+	cs2000_enable_dev_config(priv, false);
+
+	cs2000_clk_out_enable(priv, false);
+}
+
+static u8 cs2000_get_parent(struct clk_hw *hw)
+{
+	/* always return REF_CLK */
+	return REF_CLK;
+}
+
+static const struct clk_ops cs2000_ops = {
+	.get_parent	= cs2000_get_parent,
+	.recalc_rate	= cs2000_recalc_rate,
+	.round_rate	= cs2000_round_rate,
+	.set_rate	= cs2000_set_rate,
+	.prepare	= cs2000_enable,
+	.unprepare	= cs2000_disable,
+};
+
+static int cs2000_clk_get(struct cs2000_priv *priv)
+{
+	struct i2c_client *client = priv_to_client(priv);
+	struct device *dev = &client->dev;
+	struct clk *clk_in, *ref_clk;
+
+	clk_in = devm_clk_get(dev, "clk_in");
+	/* not yet provided */
+	if (IS_ERR(clk_in))
+		return -EPROBE_DEFER;
+
+	ref_clk = devm_clk_get(dev, "ref_clk");
+	/* not yet provided */
+	if (IS_ERR(ref_clk))
+		return -EPROBE_DEFER;
+
+	priv->clk_in	= clk_in;
+	priv->ref_clk	= ref_clk;
+
+	return 0;
+}
+
+static int cs2000_clk_register(struct cs2000_priv *priv)
+{
+	struct device *dev = priv_to_dev(priv);
+	struct device_node *np = dev->of_node;
+	struct clk_init_data init;
+	const char *name = np->name;
+	struct clk *clk;
+	static const char *parent_names[CLK_MAX];
+	int ch = 0; /* it uses ch0 only at this point */
+	int rate;
+	int ret;
+
+	of_property_read_string(np, "clock-output-names", &name);
+
+	/*
+	 * set default rate as 1/1.
+	 * otherwise .set_rate which setup ratio
+	 * is never called if user requests 1/1 rate
+	 */
+	rate = clk_get_rate(priv->ref_clk);
+	ret = __cs2000_set_rate(priv, ch, rate, rate);
+	if (ret < 0)
+		return ret;
+
+	parent_names[CLK_IN]	= __clk_get_name(priv->clk_in);
+	parent_names[REF_CLK]	= __clk_get_name(priv->ref_clk);
+
+	init.name		= name;
+	init.ops		= &cs2000_ops;
+	init.flags		= CLK_SET_RATE_GATE;
+	init.parent_names	= parent_names;
+	init.num_parents	= ARRAY_SIZE(parent_names);
+
+	priv->hw.init = &init;
+
+	clk = clk_register(dev, &priv->hw);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	ret = of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	if (ret < 0) {
+		clk_unregister(clk);
+		return ret;
+	}
+
+	priv->clk_out = clk;
+
+	return 0;
+}
+
+static int cs2000_version_print(struct cs2000_priv *priv)
+{
+	struct i2c_client *client = priv_to_client(priv);
+	struct device *dev = &client->dev;
+	s32 val;
+	const char *revision;
+
+	val = cs2000_read(priv, DEVICE_ID);
+	if (val < 0)
+		return val;
+
+	/* CS2000 should be 0x0 */
+	if (val >> 3)
+		return -EIO;
+
+	switch (val & REVISION_MASK) {
+	case REVISION_B2_B3:
+		revision = "B2 / B3";
+		break;
+	case REVISION_C1:
+		revision = "C1";
+		break;
+	default:
+		return -EIO;
+	}
+
+	dev_info(dev, "revision - %s\n", revision);
+
+	return 0;
+}
+
+static int cs2000_remove(struct i2c_client *client)
+{
+	struct cs2000_priv *priv = i2c_get_clientdata(client);
+	struct device *dev = &client->dev;
+	struct device_node *np = dev->of_node;
+
+	of_clk_del_provider(np);
+
+	clk_unregister(priv->clk_out);
+
+	return 0;
+}
+
+static int cs2000_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct cs2000_priv *priv;
+	struct device *dev = &client->dev;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	i2c_set_clientdata(client, priv);
+
+	ret = cs2000_clk_get(priv);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_clk_register(priv);
+	if (ret < 0)
+		return ret;
+
+	ret = cs2000_version_print(priv);
+	if (ret < 0)
+		goto probe_err;
+
+	return 0;
+
+probe_err:
+	cs2000_remove(client);
+
+	return ret;
+}
+
+static struct i2c_driver cs2000_driver = {
+	.driver = {
+		.name = "cs2000-cp",
+		.of_match_table = cs2000_of_match,
+	},
+	.probe		= cs2000_probe,
+	.remove		= cs2000_remove,
+	.id_table	= cs2000_id,
+};
+
+module_i2c_driver(cs2000_driver);
+
+MODULE_DESCRIPTION("CS2000-CP driver");
+MODULE_AUTHOR("Kuninori Morimoto <[e-mail]>");
+MODULE_LICENSE("GPL v2");