Add TI CDCE925 I2C controlled clock synthesizer driver

This driver supports the TI CDCE925 programmable clock synthesizer.
The chip contains two PLLs with spread-spectrum clocking support and
five output dividers. The driver only supports the following setup,
and uses a fixed setting for the output muxes:
  Y1 is derived from the input clock
  Y2 and Y3 derive from PLL1
  Y4 and Y5 derive from PLL2
Given a target output frequency, the driver will set the PLL and
divider to best approximate the desired output.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

4 files changed, 809 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/ti,cdce925.txt b/Documentation/devicetree/bindings/clock/ti,cdce925.txt
new file mode 100644
index 000000000000..4c7669ad681b
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/ti,cdce925.txt
@@ -0,0 +1,42 @@
+Binding for TO CDCE925 programmable I2C clock synthesizers.
+
+Reference
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] http://www.ti.com/product/cdce925
+
+The driver provides clock sources for each output Y1 through Y5.
+
+Required properties:
+ - compatible: Shall be "ti,cdce925"
+ - reg: I2C device address.
+ - clocks: Points to a fixed parent clock that provides the input frequency.
+ - #clock-cells: From common clock bindings: Shall be 1.
+
+Optional properties:
+ - xtal-load-pf: Crystal load-capacitor value to fine-tune performance on a
+                 board, or to compensate for external influences.
+
+For both PLL1 and PLL2 an optional child node can be used to specify spread
+spectrum clocking parameters for a board.
+  - spread-spectrum: SSC mode as defined in the data sheet.
+  - spread-spectrum-center: Use "centered" mode instead of "max" mode. When
+    present, the clock runs at the requested frequency on average. Otherwise
+    the requested frequency is the maximum value of the SCC range.
+
+
+Example:
+
+	clockgen: cdce925pw@64 {
+		compatible = "cdce925";
+		reg = <0x64>;
+		clocks = <&xtal_27Mhz>;
+		#clock-cells = <1>;
+		xtal-load-pf = <5>;
+		/* PLL options to get SSC 1% centered */
+		PLL2 {
+			spread-spectrum = <4>;
+			spread-spectrum-center;
+		};
+	};
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 67e3a84d2805..e33ff4e3e18d 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -78,6 +78,23 @@ config COMMON_CLK_SI570
 	  This driver supports Silicon Labs 570/571/598/599 programmable
 	  clock generators.
 
+config COMMON_CLK_CDCE925
+	tristate "Clock driver for TI CDCE925 devices"
+	depends on I2C
+	depends on OF
+	select REGMAP_I2C
+	help
+	---help---
+	  This driver supports the TI CDCE925 programmable clock synthesizer.
+	  The chip contains two PLLs with spread-spectrum clocking support and
+	  five output dividers. The driver only supports the following setup,
+	  and uses a fixed setting for the output muxes.
+	  Y1 is derived from the input clock
+	  Y2 and Y3 derive from PLL1
+	  Y4 and Y5 derive from PLL2
+	  Given a target output frequency, the driver will set the PLL and
+	  divider to best approximate the desired output.
+
 config COMMON_CLK_S2MPS11
 	tristate "Clock driver for S2MPS1X/S5M8767 MFD"
 	depends on MFD_SEC_CORE
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d965b3f6a372..00ae2de0803a 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
 obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
 obj-$(CONFIG_COMMON_CLK_SI5351)		+= clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI570)		+= clk-si570.o
+obj-$(CONFIG_COMMON_CLK_CDCE925)	+= clk-cdce925.o
 obj-$(CONFIG_CLK_TWL6040)		+= clk-twl6040.o
 obj-$(CONFIG_ARCH_U300)			+= clk-u300.o
 obj-$(CONFIG_ARCH_VT8500)		+= clk-vt8500.o
diff --git a/drivers/clk/clk-cdce925.c b/drivers/clk/clk-cdce925.c
new file mode 100644
index 000000000000..56b870d331a1
--- /dev/null
+++ b/drivers/clk/clk-cdce925.c
@@ -0,0 +1,749 @@
+/*
+ * Driver for TI Dual PLL CDCE925 clock synthesizer
+ *
+ * This driver always connects the Y1 to the input clock, Y2/Y3 to PLL1
+ * and Y4/Y5 to PLL2. PLL frequency is set on a first-come-first-serve
+ * basis. Clients can directly request any frequency that the chip can
+ * deliver using the standard clk framework. In addition, the device can
+ * be configured and activated via the devicetree.
+ *
+ * Copyright (C) 2014, Topic Embedded Products
+ * Licenced under GPL
+ */
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/gcd.h>
+
+/* The chip has 2 PLLs which can be routed through dividers to 5 outputs.
+ * Model this as 2 PLL clocks which are parents to the outputs.
+ */
+#define NUMBER_OF_PLLS	2
+#define NUMBER_OF_OUTPUTS	5
+
+#define CDCE925_REG_GLOBAL1	0x01
+#define CDCE925_REG_Y1SPIPDIVH	0x02
+#define CDCE925_REG_PDIVL	0x03
+#define CDCE925_REG_XCSEL	0x05
+/* PLL parameters start at 0x10, steps of 0x10 */
+#define CDCE925_OFFSET_PLL	0x10
+/* Add CDCE925_OFFSET_PLL * (pll) to these registers before sending */
+#define CDCE925_PLL_MUX_OUTPUTS	0x14
+#define CDCE925_PLL_MULDIV	0x18
+
+#define CDCE925_PLL_FREQUENCY_MIN	 80000000ul
+#define CDCE925_PLL_FREQUENCY_MAX	230000000ul
+struct clk_cdce925_chip;
+
+struct clk_cdce925_output {
+	struct clk_hw hw;
+	struct clk_cdce925_chip *chip;
+	u8 index;
+	u16 pdiv; /* 1..127 for Y2-Y5; 1..1023 for Y1 */
+};
+#define to_clk_cdce925_output(_hw) \
+	container_of(_hw, struct clk_cdce925_output, hw)
+
+struct clk_cdce925_pll {
+	struct clk_hw hw;
+	struct clk_cdce925_chip *chip;
+	u8 index;
+	u16 m;   /* 1..511 */
+	u16 n;   /* 1..4095 */
+};
+#define to_clk_cdce925_pll(_hw)	container_of(_hw, struct clk_cdce925_pll, hw)
+
+struct clk_cdce925_chip {
+	struct regmap *regmap;
+	struct i2c_client *i2c_client;
+	struct clk_cdce925_pll pll[NUMBER_OF_PLLS];
+	struct clk_cdce925_output clk[NUMBER_OF_OUTPUTS];
+	struct clk *dt_clk[NUMBER_OF_OUTPUTS];
+	struct clk_onecell_data onecell;
+};
+
+/* ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** */
+
+static unsigned long cdce925_pll_calculate_rate(unsigned long parent_rate,
+	u16 n, u16 m)
+{
+	if ((!m || !n) || (m == n))
+		return parent_rate; /* In bypass mode runs at same frequency */
+	return mult_frac(parent_rate, (unsigned long)n, (unsigned long)m);
+}
+
+static unsigned long cdce925_pll_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	/* Output frequency of PLL is Fout = (Fin/Pdiv)*(N/M) */
+	struct clk_cdce925_pll *data = to_clk_cdce925_pll(hw);
+
+	return cdce925_pll_calculate_rate(parent_rate, data->n, data->m);
+}
+
+static void cdce925_pll_find_rate(unsigned long rate,
+		unsigned long parent_rate, u16 *n, u16 *m)
+{
+	unsigned long un;
+	unsigned long um;
+	unsigned long g;
+
+	if (rate <= parent_rate) {
+		/* Can always deliver parent_rate in bypass mode */
+		rate = parent_rate;
+		*n = 0;
+		*m = 0;
+	} else {
+		/* In PLL mode, need to apply min/max range */
+		if (rate < CDCE925_PLL_FREQUENCY_MIN)
+			rate = CDCE925_PLL_FREQUENCY_MIN;
+		else if (rate > CDCE925_PLL_FREQUENCY_MAX)
+			rate = CDCE925_PLL_FREQUENCY_MAX;
+
+		g = gcd(rate, parent_rate);
+		um = parent_rate / g;
+		un = rate / g;
+		/* When outside hw range, reduce to fit (rounding errors) */
+		while ((un > 4095) || (um > 511)) {
+			un >>= 1;
+			um >>= 1;
+		}
+		if (un == 0)
+			un = 1;
+		if (um == 0)
+			um = 1;
+
+		*n = un;
+		*m = um;
+	}
+}
+
+static long cdce925_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long *parent_rate)
+{
+	u16 n, m;
+
+	cdce925_pll_find_rate(rate, *parent_rate, &n, &m);
+	return (long)cdce925_pll_calculate_rate(*parent_rate, n, m);
+}
+
+static int cdce925_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long parent_rate)
+{
+	struct clk_cdce925_pll *data = to_clk_cdce925_pll(hw);
+
+	if (!rate || (rate == parent_rate)) {
+		data->m = 0; /* Bypass mode */
+		data->n = 0;
+		return 0;
+	}
+
+	if ((rate < CDCE925_PLL_FREQUENCY_MIN) ||
+		(rate > CDCE925_PLL_FREQUENCY_MAX)) {
+		pr_debug("%s: rate %lu outside PLL range.\n", __func__, rate);
+		return -EINVAL;
+	}
+
+	if (rate < parent_rate) {
+		pr_debug("%s: rate %lu less than parent rate %lu.\n", __func__,
+			rate, parent_rate);
+		return -EINVAL;
+	}
+
+	cdce925_pll_find_rate(rate, parent_rate, &data->n, &data->m);
+	return 0;
+}
+
+
+/* calculate p = max(0, 4 - int(log2 (n/m))) */
+static u8 cdce925_pll_calc_p(u16 n, u16 m)
+{
+	u8 p;
+	u16 r = n / m;
+
+	if (r >= 16)
+		return 0;
+	p = 4;
+	while (r > 1) {
+		r >>= 1;
+		--p;
+	}
+	return p;
+}
+
+/* Returns VCO range bits for VCO1_0_RANGE */
+static u8 cdce925_pll_calc_range_bits(struct clk_hw *hw, u16 n, u16 m)
+{
+	struct clk *parent = clk_get_parent(hw->clk);
+	unsigned long rate = clk_get_rate(parent);
+
+	rate = mult_frac(rate, (unsigned long)n, (unsigned long)m);
+	if (rate >= 175000000)
+		return 0x3;
+	if (rate >= 150000000)
+		return 0x02;
+	if (rate >= 125000000)
+		return 0x01;
+	return 0x00;
+}
+
+/* I2C clock, hence everything must happen in (un)prepare because this
+ * may sleep */
+static int cdce925_pll_prepare(struct clk_hw *hw)
+{
+	struct clk_cdce925_pll *data = to_clk_cdce925_pll(hw);
+	u16 n = data->n;
+	u16 m = data->m;
+	u16 r;
+	u8 q;
+	u8 p;
+	u16 nn;
+	u8 pll[4]; /* Bits are spread out over 4 byte registers */
+	u8 reg_ofs = data->index * CDCE925_OFFSET_PLL;
+	unsigned i;
+
+	if ((!m || !n) || (m == n)) {
+		/* Set PLL mux to bypass mode, leave the rest as is */
+		regmap_update_bits(data->chip->regmap,
+			reg_ofs + CDCE925_PLL_MUX_OUTPUTS, 0x80, 0x80);
+	} else {
+		/* According to data sheet: */
+		/* p = max(0, 4 - int(log2 (n/m))) */
+		p = cdce925_pll_calc_p(n, m);
+		/* nn = n * 2^p */
+		nn = n * BIT(p);
+		/* q = int(nn/m) */
+		q = nn / m;
+		if ((q < 16) || (1 > 64)) {
+			pr_debug("%s invalid q=%d\n", __func__, q);
+			return -EINVAL;
+		}
+		r = nn - (m*q);
+		if (r > 511) {
+			pr_debug("%s invalid r=%d\n", __func__, r);
+			return -EINVAL;
+		}
+		pr_debug("%s n=%d m=%d p=%d q=%d r=%d\n", __func__,
+			n, m, p, q, r);
+		/* encode into register bits */
+		pll[0] = n >> 4;
+		pll[1] = ((n & 0x0F) << 4) | ((r >> 5) & 0x0F);
+		pll[2] = ((r & 0x1F) << 3) | ((q >> 3) & 0x07);
+		pll[3] = ((q & 0x07) << 5) | (p << 2) |
+				cdce925_pll_calc_range_bits(hw, n, m);
+		/* Write to registers */
+		for (i = 0; i < ARRAY_SIZE(pll); ++i)
+			regmap_write(data->chip->regmap,
+				reg_ofs + CDCE925_PLL_MULDIV + i, pll[i]);
+		/* Enable PLL */
+		regmap_update_bits(data->chip->regmap,
+			reg_ofs + CDCE925_PLL_MUX_OUTPUTS, 0x80, 0x00);
+	}
+
+	return 0;
+}
+
+static void cdce925_pll_unprepare(struct clk_hw *hw)
+{
+	struct clk_cdce925_pll *data = to_clk_cdce925_pll(hw);
+	u8 reg_ofs = data->index * CDCE925_OFFSET_PLL;
+
+	regmap_update_bits(data->chip->regmap,
+			reg_ofs + CDCE925_PLL_MUX_OUTPUTS, 0x80, 0x80);
+}
+
+static const struct clk_ops cdce925_pll_ops = {
+	.prepare = cdce925_pll_prepare,
+	.unprepare = cdce925_pll_unprepare,
+	.recalc_rate = cdce925_pll_recalc_rate,
+	.round_rate = cdce925_pll_round_rate,
+	.set_rate = cdce925_pll_set_rate,
+};
+
+
+static void cdce925_clk_set_pdiv(struct clk_cdce925_output *data, u16 pdiv)
+{
+	switch (data->index) {
+	case 0:
+		regmap_update_bits(data->chip->regmap,
+			CDCE925_REG_Y1SPIPDIVH,
+			0x03, (pdiv >> 8) & 0x03);
+		regmap_write(data->chip->regmap, 0x03, pdiv & 0xFF);
+		break;
+	case 1:
+		regmap_update_bits(data->chip->regmap, 0x16, 0x7F, pdiv);
+		break;
+	case 2:
+		regmap_update_bits(data->chip->regmap, 0x17, 0x7F, pdiv);
+		break;
+	case 3:
+		regmap_update_bits(data->chip->regmap, 0x26, 0x7F, pdiv);
+		break;
+	case 4:
+		regmap_update_bits(data->chip->regmap, 0x27, 0x7F, pdiv);
+		break;
+	}
+}
+
+static void cdce925_clk_activate(struct clk_cdce925_output *data)
+{
+	switch (data->index) {
+	case 0:
+		regmap_update_bits(data->chip->regmap,
+			CDCE925_REG_Y1SPIPDIVH, 0x0c, 0x0c);
+		break;
+	case 1:
+	case 2:
+		regmap_update_bits(data->chip->regmap, 0x14, 0x03, 0x03);
+		break;
+	case 3:
+	case 4:
+		regmap_update_bits(data->chip->regmap, 0x24, 0x03, 0x03);
+		break;
+	}
+}
+
+static int cdce925_clk_prepare(struct clk_hw *hw)
+{
+	struct clk_cdce925_output *data = to_clk_cdce925_output(hw);
+
+	cdce925_clk_set_pdiv(data, data->pdiv);
+	cdce925_clk_activate(data);
+	return 0;
+}
+
+static void cdce925_clk_unprepare(struct clk_hw *hw)
+{
+	struct clk_cdce925_output *data = to_clk_cdce925_output(hw);
+
+	/* Disable clock by setting divider to "0" */
+	cdce925_clk_set_pdiv(data, 0);
+}
+
+static unsigned long cdce925_clk_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct clk_cdce925_output *data = to_clk_cdce925_output(hw);
+
+	if (data->pdiv)
+		return parent_rate / data->pdiv;
+	return 0;
+}
+
+static u16 cdce925_calc_divider(unsigned long rate,
+		unsigned long parent_rate)
+{
+	unsigned long divider;
+
+	if (!rate)
+		return 0;
+	if (rate >= parent_rate)
+		return 1;
+
+	divider = DIV_ROUND_CLOSEST(parent_rate, rate);
+	if (divider > 0x7F)
+		divider = 0x7F;
+
+	return (u16)divider;
+}
+
+static unsigned long cdce925_clk_best_parent_rate(
+	struct clk_hw *hw, unsigned long rate)
+{
+	struct clk *pll = clk_get_parent(hw->clk);
+	struct clk *root = clk_get_parent(pll);
+	unsigned long root_rate = clk_get_rate(root);
+	unsigned long best_rate_error = rate;
+	u16 pdiv_min;
+	u16 pdiv_max;
+	u16 pdiv_best;
+	u16 pdiv_now;
+
+	if (root_rate % rate == 0)
+		return root_rate; /* Don't need the PLL, use bypass */
+
+	pdiv_min = (u16)max(1ul, DIV_ROUND_UP(CDCE925_PLL_FREQUENCY_MIN, rate));
+	pdiv_max = (u16)min(127ul, CDCE925_PLL_FREQUENCY_MAX / rate);
+
+	if (pdiv_min > pdiv_max)
+		return 0; /* No can do? */
+
+	pdiv_best = pdiv_min;
+	for (pdiv_now = pdiv_min; pdiv_now < pdiv_max; ++pdiv_now) {
+		unsigned long target_rate = rate * pdiv_now;
+		long pll_rate = clk_round_rate(pll, target_rate);
+		unsigned long actual_rate;
+		unsigned long rate_error;
+
+		if (pll_rate <= 0)
+			continue;
+		actual_rate = pll_rate / pdiv_now;
+		rate_error = abs((long)actual_rate - (long)rate);
+		if (rate_error < best_rate_error) {
+			pdiv_best = pdiv_now;
+			best_rate_error = rate_error;
+		}
+		/* TODO: Consider PLL frequency based on smaller n/m values
+		 * and pick the better one if the error is equal */
+	}
+
+	return rate * pdiv_best;
+}
+
+static long cdce925_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long *parent_rate)
+{
+	unsigned long l_parent_rate = *parent_rate;
+	u16 divider = cdce925_calc_divider(rate, l_parent_rate);
+
+	if (l_parent_rate / divider != rate) {
+		l_parent_rate = cdce925_clk_best_parent_rate(hw, rate);
+		divider = cdce925_calc_divider(rate, l_parent_rate);
+		*parent_rate = l_parent_rate;
+	}
+
+	if (divider)
+		return (long)(l_parent_rate / divider);
+	return 0;
+}
+
+static int cdce925_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long parent_rate)
+{
+	struct clk_cdce925_output *data = to_clk_cdce925_output(hw);
+
+	data->pdiv = cdce925_calc_divider(rate, parent_rate);
+
+	return 0;
+}
+
+static const struct clk_ops cdce925_clk_ops = {
+	.prepare = cdce925_clk_prepare,
+	.unprepare = cdce925_clk_unprepare,
+	.recalc_rate = cdce925_clk_recalc_rate,
+	.round_rate = cdce925_clk_round_rate,
+	.set_rate = cdce925_clk_set_rate,
+};
+
+
+static u16 cdce925_y1_calc_divider(unsigned long rate,
+		unsigned long parent_rate)
+{
+	unsigned long divider;
+
+	if (!rate)
+		return 0;
+	if (rate >= parent_rate)
+		return 1;
+
+	divider = DIV_ROUND_CLOSEST(parent_rate, rate);
+	if (divider > 0x3FF) /* Y1 has 10-bit divider */
+		divider = 0x3FF;
+
+	return (u16)divider;
+}
+
+static long cdce925_clk_y1_round_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long *parent_rate)
+{
+	unsigned long l_parent_rate = *parent_rate;
+	u16 divider = cdce925_y1_calc_divider(rate, l_parent_rate);
+
+	if (divider)
+		return (long)(l_parent_rate / divider);
+	return 0;
+}
+
+static int cdce925_clk_y1_set_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long parent_rate)
+{
+	struct clk_cdce925_output *data = to_clk_cdce925_output(hw);
+
+	data->pdiv = cdce925_y1_calc_divider(rate, parent_rate);
+
+	return 0;
+}
+
+static const struct clk_ops cdce925_clk_y1_ops = {
+	.prepare = cdce925_clk_prepare,
+	.unprepare = cdce925_clk_unprepare,
+	.recalc_rate = cdce925_clk_recalc_rate,
+	.round_rate = cdce925_clk_y1_round_rate,
+	.set_rate = cdce925_clk_y1_set_rate,
+};
+
+
+static struct regmap_config cdce925_regmap_config = {
+	.name = "configuration0",
+	.reg_bits = 8,
+	.val_bits = 8,
+	.cache_type = REGCACHE_RBTREE,
+	.max_register = 0x2F,
+};
+
+#define CDCE925_I2C_COMMAND_BLOCK_TRANSFER	0x00
+#define CDCE925_I2C_COMMAND_BYTE_TRANSFER	0x80
+
+static int cdce925_regmap_i2c_write(
+	void *context, const void *data, size_t count)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+	u8 reg_data[2];
+
+	if (count != 2)
+		return -ENOTSUPP;
+
+	/* First byte is command code */
+	reg_data[0] = CDCE925_I2C_COMMAND_BYTE_TRANSFER | ((u8 *)data)[0];
+	reg_data[1] = ((u8 *)data)[1];
+
+	dev_dbg(&i2c->dev, "%s(%zu) %#x %#x\n", __func__, count,
+			reg_data[0], reg_data[1]);
+
+	ret = i2c_master_send(i2c, reg_data, count);
+	if (likely(ret == count))
+		return 0;
+	else if (ret < 0)
+		return ret;
+	else
+		return -EIO;
+}
+
+static int cdce925_regmap_i2c_read(void *context,
+	   const void *reg, size_t reg_size, void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct i2c_msg xfer[2];
+	int ret;
+	u8 reg_data[2];
+
+	if (reg_size != 1)
+		return -ENOTSUPP;
+
+	xfer[0].addr = i2c->addr;
+	xfer[0].flags = 0;
+	xfer[0].buf = reg_data;
+	if (val_size == 1) {
+		reg_data[0] =
+			CDCE925_I2C_COMMAND_BYTE_TRANSFER | ((u8 *)reg)[0];
+		xfer[0].len = 1;
+	} else {
+		reg_data[0] =
+			CDCE925_I2C_COMMAND_BLOCK_TRANSFER | ((u8 *)reg)[0];
+		reg_data[1] = val_size;
+		xfer[0].len = 2;
+	}
+
+	xfer[1].addr = i2c->addr;
+	xfer[1].flags = I2C_M_RD;
+	xfer[1].len = val_size;
+	xfer[1].buf = val;
+
+	ret = i2c_transfer(i2c->adapter, xfer, 2);
+	if (likely(ret == 2)) {
+		dev_dbg(&i2c->dev, "%s(%zu, %u) %#x %#x\n", __func__,
+				reg_size, val_size, reg_data[0], *((u8 *)val));
+		return 0;
+	} else if (ret < 0)
+		return ret;
+	else
+		return -EIO;
+}
+
+/* The CDCE925 uses a funky way to read/write registers. Bulk mode is
+ * just weird, so just use the single byte mode exclusively. */
+static struct regmap_bus regmap_cdce925_bus = {
+	.write = cdce925_regmap_i2c_write,
+	.read = cdce925_regmap_i2c_read,
+};
+
+static int cdce925_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct clk_cdce925_chip *data;
+	struct device_node *node = client->dev.of_node;
+	const char *parent_name;
+	const char *pll_clk_name[NUMBER_OF_PLLS] = {NULL,};
+	struct clk_init_data init;
+	struct clk *clk;
+	u32 value;
+	int i;
+	int err;
+	struct device_node *np_output;
+	char child_name[6];
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->i2c_client = client;
+	data->regmap = devm_regmap_init(&client->dev, &regmap_cdce925_bus,
+			&client->dev, &cdce925_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "failed to allocate register map\n");
+		return PTR_ERR(data->regmap);
+	}
+	i2c_set_clientdata(client, data);
+
+	parent_name = of_clk_get_parent_name(node, 0);
+	if (!parent_name) {
+		dev_err(&client->dev, "missing parent clock\n");
+		return -ENODEV;
+	}
+	dev_dbg(&client->dev, "parent is: %s\n", parent_name);
+
+	if (of_property_read_u32(node, "xtal-load-pf", &value) == 0)
+		regmap_write(data->regmap,
+			CDCE925_REG_XCSEL, (value << 3) & 0xF8);
+	/* PWDN bit */
+	regmap_update_bits(data->regmap, CDCE925_REG_GLOBAL1, BIT(4), 0);
+
+	/* Set input source for Y1 to be the XTAL */
+	regmap_update_bits(data->regmap, 0x02, BIT(7), 0);
+
+	init.ops = &cdce925_pll_ops;
+	init.flags = 0;
+	init.parent_names = &parent_name;
+	init.num_parents = parent_name ? 1 : 0;
+
+	/* Register PLL clocks */
+	for (i = 0; i < NUMBER_OF_PLLS; ++i) {
+		pll_clk_name[i] = kasprintf(GFP_KERNEL, "%s.pll%d",
+			client->dev.of_node->name, i);
+		init.name = pll_clk_name[i];
+		data->pll[i].chip = data;
+		data->pll[i].hw.init = &init;
+		data->pll[i].index = i;
+		clk = devm_clk_register(&client->dev, &data->pll[i].hw);
+		if (IS_ERR(clk)) {
+			dev_err(&client->dev, "Failed register PLL %d\n", i);
+			err = PTR_ERR(clk);
+			goto error;
+		}
+		sprintf(child_name, "PLL%d", i+1);
+		np_output = of_get_child_by_name(node, child_name);
+		if (!np_output)
+			continue;
+		if (!of_property_read_u32(np_output,
+			"clock-frequency", &value)) {
+			err = clk_set_rate(clk, value);
+			if (err)
+				dev_err(&client->dev,
+					"unable to set PLL frequency %ud\n",
+					value);
+		}
+		if (!of_property_read_u32(np_output,
+			"spread-spectrum", &value)) {
+			u8 flag = of_property_read_bool(np_output,
+				"spread-spectrum-center") ? 0x80 : 0x00;
+			regmap_update_bits(data->regmap,
+				0x16 + (i*CDCE925_OFFSET_PLL),
+				0x80, flag);
+			regmap_update_bits(data->regmap,
+				0x12 + (i*CDCE925_OFFSET_PLL),
+				0x07, value & 0x07);
+		}
+	}
+
+	/* Register output clock Y1 */
+	init.ops = &cdce925_clk_y1_ops;
+	init.flags = 0;
+	init.num_parents = 1;
+	init.parent_names = &parent_name; /* Mux Y1 to input */
+	init.name = kasprintf(GFP_KERNEL, "%s.Y1", client->dev.of_node->name);
+	data->clk[0].chip = data;
+	data->clk[0].hw.init = &init;
+	data->clk[0].index = 0;
+	data->clk[0].pdiv = 1;
+	clk = devm_clk_register(&client->dev, &data->clk[0].hw);
+	kfree(init.name); /* clock framework made a copy of the name */
+	if (IS_ERR(clk)) {
+		dev_err(&client->dev, "clock registration Y1 failed\n");
+		err = PTR_ERR(clk);
+		goto error;
+	}
+	data->dt_clk[0] = clk;
+
+	/* Register output clocks Y2 .. Y5*/
+	init.ops = &cdce925_clk_ops;
+	init.flags = CLK_SET_RATE_PARENT;
+	init.num_parents = 1;
+	for (i = 1; i < NUMBER_OF_OUTPUTS; ++i) {
+		init.name = kasprintf(GFP_KERNEL, "%s.Y%d",
+			client->dev.of_node->name, i+1);
+		data->clk[i].chip = data;
+		data->clk[i].hw.init = &init;
+		data->clk[i].index = i;
+		data->clk[i].pdiv = 1;
+		switch (i) {
+		case 1:
+		case 2:
+			/* Mux Y2/3 to PLL1 */
+			init.parent_names = &pll_clk_name[0];
+			break;
+		case 3:
+		case 4:
+			/* Mux Y4/5 to PLL2 */
+			init.parent_names = &pll_clk_name[1];
+			break;
+		}
+		clk = devm_clk_register(&client->dev, &data->clk[i].hw);
+		kfree(init.name); /* clock framework made a copy of the name */
+		if (IS_ERR(clk)) {
+			dev_err(&client->dev, "clock registration failed\n");
+			err = PTR_ERR(clk);
+			goto error;
+		}
+		data->dt_clk[i] = clk;
+	}
+
+	/* Register the output clocks */
+	data->onecell.clk_num = NUMBER_OF_OUTPUTS;
+	data->onecell.clks = data->dt_clk;
+	err = of_clk_add_provider(client->dev.of_node, of_clk_src_onecell_get,
+		&data->onecell);
+	if (err)
+		dev_err(&client->dev, "unable to add OF clock provider\n");
+
+	err = 0;
+
+error:
+	for (i = 0; i < NUMBER_OF_PLLS; ++i)
+		/* clock framework made a copy of the name */
+		kfree(pll_clk_name[i]);
+
+	return err;
+}
+
+static const struct i2c_device_id cdce925_id[] = {
+	{ "cdce925", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cdce925_id);
+
+static const struct of_device_id clk_cdce925_of_match[] = {
+	{ .compatible = "ti,cdce925" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, clk_cdce925_of_match);
+
+static struct i2c_driver cdce925_driver = {
+	.driver = {
+		.name = "cdce925",
+		.of_match_table = of_match_ptr(clk_cdce925_of_match),
+	},
+	.probe		= cdce925_probe,
+	.id_table	= cdce925_id,
+};
+module_i2c_driver(cdce925_driver);
+
+MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
+MODULE_DESCRIPTION("cdce925 driver");
+MODULE_LICENSE("GPL");