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Date:   Sat, 18 May 2019 10:48:39 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Stefan Popa <stefan.popa@analog.com>
Cc:     <Michael.Hennerich@analog.com>, <knaack.h@gmx.de>,
        <lars@metafoo.de>, <pmeerw@pmeerw.net>,
        <gregkh@linuxfoundation.org>, <linux-kernel@vger.kernel.org>,
        <linux-iio@vger.kernel.org>
Subject: Re: [PATCH 1/2] iio: frequency: adf4371: Add support for ADF4371
 PLL
Message-ID: <20190518104839.3f86fe7c@archlinux>
In-Reply-To: <1557918014-25614-1-git-send-email-stefan.popa@analog.com>
References: <1557918014-25614-1-git-send-email-stefan.popa@analog.com>
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On Wed, 15 May 2019 14:00:14 +0300
Stefan Popa <stefan.popa@analog.com> wrote:

> The ADF4371 is a frequency synthesizer with an integrated voltage
> controlled oscillator (VCO) for phase-locked loops (PLLs). The ADF4371
> has an integrated VCO with a fundamental output frequency ranging from
> 4000 MHz to 8000 MHz. In addition, the VCO frequency is connected to
> divide by 1, 2, 4, 8, 16, 32, or 64 circuits that allows the user to
> generate radio frequency (RF) output frequencies as low as 62.5 MHz at
> RF8x. A frequency multiplier at RF16x generates from 8 GHz to 16 GHz. A
> frequency quadrupler generates frequencies from 16 GHz to 32 GHz at RF32x.
> RFAUX8x duplicates the frequency range of RF8x or permits direct access to
> the VCO output.
>=20
> The driver takes the reference input frequency from the device tree and
> uses it to calculate and maximize the PFD frequency (frequency of the pha=
se
> frequency detector). The PFD frequency is further used to calculate the
> timeouts: synthesizer lock, VCO band selection, automatic level
> calibration (ALC) and PLL settling time.
>=20
> This initial driver exposes the attributes for setting the frequency and
> enabling/disabling the different adf4371 channels.
>=20
> Datasheet:
> Link: https://www.analog.com/media/en/technical-documentation/data-sheets=
/adf4371.pdf
>=20
> Signed-off-by: Stefan Popa <stefan.popa@analog.com>
You are making use of extend_name, which means we have new ABI defined here.
Definitely needs a doc.

A few other minor things inline.

Jonathan

> ---
>  drivers/iio/frequency/Kconfig   |  10 +
>  drivers/iio/frequency/Makefile  |   1 +
>  drivers/iio/frequency/adf4371.c | 573 ++++++++++++++++++++++++++++++++++=
++++++
>  3 files changed, 584 insertions(+)
>  create mode 100644 drivers/iio/frequency/adf4371.c
>=20
> diff --git a/drivers/iio/frequency/Kconfig b/drivers/iio/frequency/Kconfig
> index dc5e0b7..e4a921f 100644
> --- a/drivers/iio/frequency/Kconfig
> +++ b/drivers/iio/frequency/Kconfig
> @@ -38,5 +38,15 @@ config ADF4350
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called adf4350.
> =20
> +config ADF4371
> +	tristate "Analog Devices ADF4371 Wideband Synthesizer"
> +	depends on SPI
> +	select REGMAP_SPI
> +	help
> +	  Say yes here to build support for Analog Devices  ADF4371
> +	  Wideband Synthesizer. The driver provides direct access via sysfs.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called adf4371.
>  endmenu
>  endmenu
> diff --git a/drivers/iio/frequency/Makefile b/drivers/iio/frequency/Makef=
ile
> index 2bca03f..2ddda77 100644
> --- a/drivers/iio/frequency/Makefile
> +++ b/drivers/iio/frequency/Makefile
> @@ -5,3 +5,4 @@
>  # When adding new entries keep the list in alphabetical order
>  obj-$(CONFIG_AD9523) +=3D ad9523.o
>  obj-$(CONFIG_ADF4350) +=3D adf4350.o
> +obj-$(CONFIG_ADF4371) +=3D adf4371.o
> diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4=
371.c
> new file mode 100644
> index 0000000..fd968d5
> --- /dev/null
> +++ b/drivers/iio/frequency/adf4371.c
> @@ -0,0 +1,573 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Analog Devices ADF4371 SPI Wideband Synthesizer driver
> + *
> + * Copyright 2019 Analog Devices Inc.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/gcd.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/sysfs.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +
> +/* Registers address macro */
> +#define ADF4371_REG(x) (0x ## x)
Why?  Just put them in hex in the first place as more readable?

> +
> +/* ADF4371_REG0 */
> +#define ADF4371_ADDR_ASC_MSK		BIT(2)
> +#define ADF4371_ADDR_ASC(x)		FIELD_PREP(ADF4371_ADDR_ASC_MSK, x)
> +#define ADF4371_ADDR_ASC_R_MSK		BIT(5)
> +#define ADF4371_ADDR_ASC_R(x)		FIELD_PREP(ADF4371_ADDR_ASC_R_MSK, x)
> +#define ADF4371_RESET_CMD		0x81
> +
> +/* ADF4371_REG17 */
> +#define ADF4371_FRAC2WORD_L_MSK		GENMASK(7, 1)
> +#define ADF4371_FRAC2WORD_L(x)		FIELD_PREP(ADF4371_FRAC2WORD_L_MSK, x)
> +#define ADF4371_FRAC1WORD_MSK		BIT(0)
> +#define ADF4371_FRAC1WORD(x)		FIELD_PREP(ADF4371_FRAC1WORD_MSK, x)
> +
> +/* ADF4371_REG18 */
> +#define ADF4371_FRAC2WORD_H_MSK		GENMASK(6, 0)
> +#define ADF4371_FRAC2WORD_H(x)		FIELD_PREP(ADF4371_FRAC2WORD_H_MSK, x)
> +
> +/* ADF4371_REG1A */
> +#define ADF4371_MOD2WORD_MSK		GENMASK(5, 0)
> +#define ADF4371_MOD2WORD(x)		FIELD_PREP(ADF4371_MOD2WORD_MSK, x)
> +
> +/* ADF4371_REG24 */
> +#define ADF4371_RF_DIV_SEL_MSK		GENMASK(6, 4)
> +#define ADF4371_RF_DIV_SEL(x)		FIELD_PREP(ADF4371_RF_DIV_SEL_MSK, x)
> +
> +/* ADF4371_REG32 */
> +#define ADF4371_TIMEOUT_MSK		GENMASK(1, 0)
> +#define ADF4371_TIMEOUT(x)		FIELD_PREP(ADF4371_TIMEOUT_MSK, x)
> +
> +/* ADF4371_REG34 */
> +#define ADF4371_VCO_ALC_TOUT_MSK	GENMASK(4, 0)
> +#define ADF4371_VCO_ALC_TOUT(x)		FIELD_PREP(ADF4371_VCO_ALC_TOUT_MSK, x)
> +
> +/* Specifications */
> +#define ADF4371_MIN_VCO_FREQ		4000000000ULL /* 4000 MHz */
> +#define ADF4371_MAX_VCO_FREQ		8000000000ULL /* 8000 MHz */
> +#define ADF4371_MAX_OUT_RF8_FREQ	ADF4371_MAX_VCO_FREQ /* Hz */
> +#define ADF4371_MIN_OUT_RF8_FREQ	(ADF4371_MIN_VCO_FREQ / 64) /* Hz */
> +#define ADF4371_MAX_OUT_RF16_FREQ	(ADF4371_MAX_VCO_FREQ * 2) /* Hz */
> +#define ADF4371_MIN_OUT_RF16_FREQ	(ADF4371_MIN_VCO_FREQ * 2) /* Hz */
> +#define ADF4371_MAX_OUT_RF32_FREQ	(ADF4371_MAX_VCO_FREQ * 4) /* Hz */
> +#define ADF4371_MIN_OUT_RF32_FREQ	(ADF4371_MIN_VCO_FREQ * 4) /* Hz */
> +
> +#define ADF4371_MAX_FREQ_PFD		250000000UL /* Hz */
> +#define ADF4371_MAX_FREQ_REFIN		600000000UL /* Hz */
> +
> +/* MOD1 is a 24-bit primary modulus with fixed value of 2^25 */
> +#define ADF4371_MODULUS1		33554432ULL
> +/* MOD2 is the programmable, 14-bit auxiliary fractional modulus */
> +#define ADF4371_MAX_MODULUS2		16384

BIT(14) maybe?

> +
> +#define ADF4371_CHECK_RANGE(freq, range) \
> +	((freq > ADF4371_MAX_ ## range) || (freq < ADF4371_MIN_ ## range))
> +
> +enum {
> +	ADF4371_FREQ,
> +	ADF4371_POWER_DOWN
> +};
> +
> +enum {
> +	ADF4371_CH_RF8,
> +	ADF4371_CH_RF16,
> +	ADF4371_CH_RF32,
> +	ADF4371_CH_RFAUX8
> +};
> +
> +struct adf4371_pwrdown {
> +	unsigned int reg;
> +	unsigned int bit;
> +};
> +
> +static const struct adf4371_pwrdown adf4371_pwrdown_ch[4] =3D {
> +	[ADF4371_CH_RF8] =3D { ADF4371_REG(25), 2 },
> +	[ADF4371_CH_RF16] =3D { ADF4371_REG(25), 3 },
> +	[ADF4371_CH_RF32] =3D { ADF4371_REG(25), 4 },
> +	[ADF4371_CH_RFAUX8] =3D { ADF4371_REG(72), 3 }
> +};
> +
> +static const struct reg_sequence adf4371_reg_defaults[] =3D {
> +	{ ADF4371_REG(0),  0x18 },
> +	{ ADF4371_REG(12), 0x40 },
> +	{ ADF4371_REG(1E), 0x48 },
> +	{ ADF4371_REG(20), 0x14 },
> +	{ ADF4371_REG(22), 0x00 },
> +	{ ADF4371_REG(23), 0x00 },
> +	{ ADF4371_REG(24), 0x80 },
> +	{ ADF4371_REG(25), 0x07 },
> +	{ ADF4371_REG(27), 0xC5 },
> +	{ ADF4371_REG(28), 0x83 },
> +	{ ADF4371_REG(2C), 0x44 },
> +	{ ADF4371_REG(2D), 0x11 },
> +	{ ADF4371_REG(2E), 0x12 },
> +	{ ADF4371_REG(2F), 0x94 },
> +	{ ADF4371_REG(32), 0x04 },
> +	{ ADF4371_REG(35), 0xFA },
> +	{ ADF4371_REG(36), 0x30 },
> +	{ ADF4371_REG(39), 0x07 },
> +	{ ADF4371_REG(3A), 0x55 },
> +	{ ADF4371_REG(3E), 0x0C },
> +	{ ADF4371_REG(3F), 0x80 },
> +	{ ADF4371_REG(40), 0x50 },
> +	{ ADF4371_REG(41), 0x28 },
> +	{ ADF4371_REG(47), 0xC0 },
> +	{ ADF4371_REG(52), 0xF4 },
> +	{ ADF4371_REG(70), 0x03 },
> +	{ ADF4371_REG(71), 0x60 },
> +	{ ADF4371_REG(72), 0x32 },
> +};
> +
> +static const struct regmap_config adf4371_regmap_config =3D {
> +	.reg_bits =3D 16,
> +	.val_bits =3D 8,
> +	.read_flag_mask =3D BIT(7),
> +};
> +
> +struct adf4371_state {
> +	struct spi_device *spi;
> +	struct regmap *regmap;
> +	struct clk *clkin;
> +	struct mutex lock;
> +	unsigned long clkin_freq;
> +	unsigned long fpfd;
> +	unsigned int integer;
> +	unsigned int fract1;
> +	unsigned int fract2;
> +	unsigned int mod2;
> +	unsigned int rf_div_sel;
> +	unsigned int ref_div_factor;
> +};
> +
> +static unsigned long long adf4371_pll_fract_n_get_rate(struct adf4371_st=
ate *st,
> +						       u32 channel)
> +{
> +	unsigned long long val, tmp;
> +	unsigned int ref_div_sel;
> +
> +	val =3D (((u64)st->integer * ADF4371_MODULUS1) + st->fract1) * st->fpfd;
> +	tmp =3D (u64)st->fract2 * st->fpfd;
> +	do_div(tmp, st->mod2);
> +	val +=3D tmp + ADF4371_MODULUS1 / 2;
> +
> +	if (channel =3D=3D ADF4371_CH_RF8 || channel =3D=3D ADF4371_CH_RFAUX8)
> +		ref_div_sel =3D st->rf_div_sel;
> +	else
> +		ref_div_sel =3D 0;
> +
> +	do_div(val, ADF4371_MODULUS1 * (1 << ref_div_sel));
> +
> +	if (channel =3D=3D ADF4371_CH_RF16)
> +		val <<=3D 1;
> +	else if (channel =3D=3D ADF4371_CH_RF32)
> +		val <<=3D 2;
> +
> +	return val;
> +}
> +
> +static void adf4371_pll_fract_n_compute(unsigned long long vco,
> +				       unsigned long long pfd,
> +				       unsigned int *integer,
> +				       unsigned int *fract1,
> +				       unsigned int *fract2,
> +				       unsigned int *mod2)
> +{
> +	unsigned long long tmp;
> +	u32 gcd_div;
> +
> +	tmp =3D do_div(vco, pfd);
> +	tmp =3D tmp * ADF4371_MODULUS1;
> +	*fract2 =3D do_div(tmp, pfd);
> +
> +	*integer =3D vco;
> +	*fract1 =3D tmp;
> +
> +	*mod2 =3D pfd;
> +
> +	while (*mod2 > ADF4371_MAX_MODULUS2) {
> +		*mod2 >>=3D 1;
> +		*fract2 >>=3D 1;
> +	}
> +
> +	gcd_div =3D gcd(*fract2, *mod2);
> +	*mod2 /=3D gcd_div;
> +	*fract2 /=3D gcd_div;
> +}
> +
> +static int adf4371_set_freq(struct adf4371_state *st, unsigned long long=
 freq,
> +			    unsigned int channel)
> +{
> +	u32 cp_bleed;
> +	u8 buf[10], int_mode =3D 0;
> +	int ret;
> +
> +	switch (channel) {
> +	case ADF4371_CH_RF8:
> +	case ADF4371_CH_RFAUX8:
> +		if (ADF4371_CHECK_RANGE(freq, OUT_RF8_FREQ))
> +			return -EINVAL;
> +
> +		st->rf_div_sel =3D 0;
> +
> +		while (freq < ADF4371_MIN_VCO_FREQ) {
> +			freq <<=3D 1;
> +			st->rf_div_sel++;
> +		}
> +		break;
> +	case ADF4371_CH_RF16:
> +		/* ADF4371 RF16 8000...16000 MHz */
> +		if (ADF4371_CHECK_RANGE(freq, OUT_RF16_FREQ))
> +			return -EINVAL;
> +
> +		freq >>=3D 1;
> +		break;
> +	case ADF4371_CH_RF32:
> +		/* ADF4371 RF32 16000...32000 MHz */
> +		if (ADF4371_CHECK_RANGE(freq, OUT_RF32_FREQ))
> +			return -EINVAL;
> +
> +		freq >>=3D 2;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	adf4371_pll_fract_n_compute(freq, st->fpfd, &st->integer, &st->fract1,
> +				    &st->fract2, &st->mod2);
> +	buf[0] =3D st->integer >> 8;
> +	buf[1] =3D 0x40; /* REG12 default */
> +	buf[2] =3D 0x00;
> +	buf[3] =3D st->fract2 & 0xFF;
> +	buf[4] =3D st->fract2 >> 7;
> +	buf[5] =3D st->fract2 >> 15;
> +	buf[6] =3D ADF4371_FRAC2WORD_L(st->fract2 & 0x7F) |
> +		 ADF4371_FRAC1WORD(st->fract1 >> 23);
> +	buf[7] =3D ADF4371_FRAC2WORD_H(st->fract2 >> 7);
> +	buf[8] =3D st->mod2 & 0xFF;
> +	buf[9] =3D ADF4371_MOD2WORD(st->mod2 >> 8);
> +
> +	ret =3D regmap_bulk_write(st->regmap, ADF4371_REG(11),
> +				buf, ARRAY_SIZE(buf));

I've not checked recently, but IIRC regmap_bulk_write
can do DMA directly with the buffer.  This one isn't DMA safe
as not forced into it's own cacheline.

> +	if (ret < 0)
> +		return ret;
> +	/*
> +	 * The R counter allows the input reference frequency to be
> +	 * divided down to produce the reference clock to the PFD
> +	 */
> +	ret =3D regmap_write(st->regmap, ADF4371_REG(1F), st->ref_div_factor);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =3D regmap_update_bits(st->regmap, ADF4371_REG(24),
> +				 ADF4371_RF_DIV_SEL_MSK,
> +				 ADF4371_RF_DIV_SEL(st->rf_div_sel));
> +	if (ret < 0)
> +		return ret;
> +
> +	cp_bleed =3D DIV_ROUND_UP(400 * 1750, st->integer * 375);
> +	cp_bleed =3D clamp(cp_bleed, 1U, 255U);
> +	ret =3D regmap_write(st->regmap, ADF4371_REG(26), cp_bleed);
> +	if (ret < 0)
> +		return ret;
> +	/*
> +	 * Set to 1 when in INT mode (when FRAC1 =3D FRAC2 =3D 0),
> +	 * and set to 0 when in FRAC mode.
> +	 */
> +	if (st->fract1 =3D=3D 0 && st->fract2 =3D=3D 0)
> +		int_mode =3D 0x01;
> +
> +	ret =3D regmap_write(st->regmap, ADF4371_REG(2B), int_mode);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regmap_write(st->regmap, ADF4371_REG(10), st->integer & 0xFF);
> +}
> +
> +static ssize_t adf4371_read(struct iio_dev *indio_dev,
> +			    uintptr_t private,
> +			    const struct iio_chan_spec *chan,
> +			    char *buf)
> +{
> +	struct adf4371_state *st =3D iio_priv(indio_dev);
> +	unsigned long long val =3D 0;
> +	unsigned int readval, reg, bit;
> +	int ret;
> +
> +	switch ((u32)private) {
> +	case ADF4371_FREQ:
> +		val =3D adf4371_pll_fract_n_get_rate(st, chan->channel);
> +		ret =3D regmap_read(st->regmap, ADF4371_REG(7C), &readval);
> +		if (ret < 0)
> +			break;
> +
> +		if (readval =3D=3D 0x00) {
> +			dev_dbg(&st->spi->dev, "PLL un-locked\n");
> +			ret =3D -EBUSY;
> +		}
> +		break;
> +	case ADF4371_POWER_DOWN:
> +		reg =3D adf4371_pwrdown_ch[chan->channel].reg;
> +		bit =3D adf4371_pwrdown_ch[chan->channel].bit;
> +
> +		ret =3D regmap_read(st->regmap, reg, &readval);
> +		if (ret < 0)
> +			break;
> +
> +		val =3D !(readval & BIT(bit));
> +		break;
> +	default:
> +		ret =3D -EINVAL;
> +		val =3D 0;
> +		break;
> +	}
> +
> +	return ret < 0 ? ret : sprintf(buf, "%llu\n", val);
> +}
> +
> +static ssize_t adf4371_write(struct iio_dev *indio_dev,
> +			     uintptr_t private,
> +			     const struct iio_chan_spec *chan,
> +			     const char *buf, size_t len)
> +{
> +	struct adf4371_state *st =3D iio_priv(indio_dev);
> +	unsigned long long readin;
> +	unsigned int bit, readval, reg;
> +	int ret;
> +
> +	ret =3D kstrtoull(buf, 10, &readin);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&st->lock);
> +	switch ((u32)private) {
> +	case ADF4371_FREQ:
> +		ret =3D adf4371_set_freq(st, readin, chan->channel);
> +		break;
> +	case ADF4371_POWER_DOWN:
> +		reg =3D adf4371_pwrdown_ch[chan->channel].reg;
> +		bit =3D adf4371_pwrdown_ch[chan->channel].bit;
> +		ret =3D regmap_read(st->regmap, reg, &readval);
> +		if (ret < 0)
> +			break;
> +
> +		readval &=3D ~BIT(bit);
> +		readval |=3D (!readin << bit);
> +
> +		ret =3D regmap_write(st->regmap, reg, readval);
> +		break;
> +	default:
> +		ret =3D -EINVAL;
> +		break;
> +	}
> +	mutex_unlock(&st->lock);
> +
> +	return ret ? ret : len;
> +}
> +
> +#define _ADF4371_EXT_INFO(_name, _ident) { \
> +		.name =3D _name, \
> +		.read =3D adf4371_read, \
> +		.write =3D adf4371_write, \
> +		.private =3D _ident, \
> +		.shared =3D IIO_SEPARATE, \
> +}
> +
> +static const struct iio_chan_spec_ext_info adf4371_ext_info[] =3D {
> +	/* Ideally we use IIO_CHAN_INFO_FREQUENCY, but there are
comment style...

> +	 * values > 2^32 in order to support the entire frequency range
> +	 * in Hz. Using scale is a bit ugly.

Hmm. We could add a new IIO_VAL type for say INT + GIGA or something like
that. I doubt this will be the last time we hit this.  Or potentially
just define a 64 bit raw format, packed into the two 32bit numbers,
though that is a bit ugly.

Can fix that later though.

> +	 */
> +	_ADF4371_EXT_INFO("frequency", ADF4371_FREQ),
> +	_ADF4371_EXT_INFO("powerdown", ADF4371_POWER_DOWN),
> +	{ },
> +};
> +
> +#define ADF4371_CHANNEL(_name, index) { \
> +		.type =3D IIO_ALTVOLTAGE, \
> +		.output =3D 1, \
> +		.channel =3D index, \
> +		.ext_info =3D adf4371_ext_info, \
> +		.extend_name =3D _name, \
> +	}
> +
> +static const struct iio_chan_spec adf4371_chan[] =3D {
> +	ADF4371_CHANNEL("rf8", ADF4371_CH_RF8),
> +	ADF4371_CHANNEL("rf16", ADF4371_CH_RF16),
> +	ADF4371_CHANNEL("rf32", ADF4371_CH_RF32),
> +	ADF4371_CHANNEL("rfaux8", ADF4371_CH_RFAUX8),
> +};
> +
> +static int adf4371_reg_access(struct iio_dev *indio_dev,
> +			      unsigned int reg,
> +			      unsigned int writeval,
> +			      unsigned int *readval)
> +{
> +	struct adf4371_state *st =3D iio_priv(indio_dev);
> +
> +	if (readval)
> +		return regmap_read(st->regmap, reg, readval);
> +	else
> +		return regmap_write(st->regmap, reg, writeval);
> +}
> +
> +static const struct iio_info adf4371_info =3D {
> +	.debugfs_reg_access =3D &adf4371_reg_access,
> +};
> +
> +static int adf4371_setup(struct adf4371_state *st)
> +{
> +	unsigned int synth_timeout =3D 2, timeout =3D 1, vco_alc_timeout =3D 1;
> +	unsigned int vco_band_div, tmp;
> +	u8 buf[5];
> +	int ret;
> +
> +	/* Perform a software reset */
> +	ret =3D regmap_write(st->regmap, ADF4371_REG(0), ADF4371_RESET_CMD);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =3D regmap_multi_reg_write(st->regmap, adf4371_reg_defaults,
> +				     ARRAY_SIZE(adf4371_reg_defaults));
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Set address in ascending order, so the bulk_write() will work */
> +	ret =3D regmap_update_bits(st->regmap, ADF4371_REG(0),
> +				 ADF4371_ADDR_ASC_MSK | ADF4371_ADDR_ASC_R_MSK,
> +				 ADF4371_ADDR_ASC(1) | ADF4371_ADDR_ASC_R(1));
> +	if (ret < 0)
> +		return ret;
> +	/*
> +	 * Calculate and maximize PFD frequency
> +	 * fPFD =3D REFIN =C3=97 ((1 + D)/(R =C3=97 (1 + T)))
> +	 * Where D is the REFIN doubler bit, T is the reference divide by 2,
> +	 * R is the reference division factor
> +	 * TODO: it is assumed D and T equal 0.
> +	 */
> +	do {
> +		st->ref_div_factor++;
> +		st->fpfd =3D st->clkin_freq / st->ref_div_factor;
> +	} while (st->fpfd > ADF4371_MAX_FREQ_PFD);
> +
> +	/* Calculate Timeouts */
> +	vco_band_div =3D DIV_ROUND_UP(st->fpfd, 2400000U);
> +
> +	tmp =3D DIV_ROUND_CLOSEST(st->fpfd, 1000000U);
> +	do {
> +		timeout++;
> +		if (timeout > 1023) {
> +			timeout =3D 2;
> +			synth_timeout++;
> +		}
> +	} while (synth_timeout * 1024 + timeout <=3D 20 * tmp);
> +
> +	do {
> +		vco_alc_timeout++;
> +	} while (vco_alc_timeout * 1024 - timeout <=3D 50 * tmp);
> +
> +	buf[0] =3D vco_band_div;
> +	buf[1] =3D timeout & 0xFF;
> +	buf[2] =3D ADF4371_TIMEOUT(timeout >> 8) | 0x04;
> +	buf[3] =3D synth_timeout;
> +	buf[4] =3D ADF4371_VCO_ALC_TOUT(vco_alc_timeout);
> +
> +	return regmap_bulk_write(st->regmap, ADF4371_REG(30),
> +				 buf, ARRAY_SIZE(buf));
> +}
> +
> +static void adf4371_clk_disable(void *data)
> +{
> +	struct adf4371_state *st =3D data;
> +
> +	clk_disable_unprepare(st->clkin);
> +}
> +
> +static int adf4371_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct adf4371_state *st;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	indio_dev =3D devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	regmap =3D devm_regmap_init_spi(spi, &adf4371_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(&spi->dev, "Error initializing spi regmap: %ld\n",
> +			PTR_ERR(regmap));
> +		return PTR_ERR(regmap);
> +	}
> +
> +	st =3D iio_priv(indio_dev);
> +	spi_set_drvdata(spi, indio_dev);
> +	st->regmap =3D regmap;
> +	mutex_init(&st->lock);
> +
> +	indio_dev->dev.parent =3D &spi->dev;
> +	indio_dev->name =3D spi_get_device_id(spi)->name;
> +	indio_dev->info =3D &adf4371_info;
> +	indio_dev->modes =3D INDIO_DIRECT_MODE;
> +	indio_dev->channels =3D adf4371_chan;
> +	indio_dev->num_channels =3D ARRAY_SIZE(adf4371_chan);
> +
> +	st->clkin =3D devm_clk_get(&spi->dev, "clkin");
> +	if (IS_ERR(st->clkin))
> +		return PTR_ERR(st->clkin);
> +
> +	ret =3D clk_prepare_enable(st->clkin);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =3D devm_add_action_or_reset(&spi->dev, adf4371_clk_disable, st);
> +	if (ret)
> +		return ret;
> +
> +	st->clkin_freq =3D clk_get_rate(st->clkin);
> +
> +	ret =3D adf4371_setup(st);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "ADF4371 setup failed\n");
> +		return ret;
> +	}
> +
> +	return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct spi_device_id adf4371_id_table[] =3D {
> +	{ "adf4371", 0 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, adf4371_id_table);
> +
> +static const struct of_device_id adf4371_of_match[] =3D {
> +	{ .compatible =3D "adi,adf4371" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, adf4371_of_match);
> +
> +static struct spi_driver adf4371_driver =3D {
> +	.driver =3D {
> +		.name =3D "adf4371",
> +		.of_match_table =3D adf4371_of_match,
> +	},
> +	.probe =3D adf4371_probe,
> +	.id_table =3D adf4371_id_table,
> +};
> +module_spi_driver(adf4371_driver);
> +
> +MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices ADF4371 SPI PLL");
> +MODULE_LICENSE("GPL");