Date:   Fri, 18 Feb 2022 11:50:48 +0200
From:   Cristian Pop <cristian.pop@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>, <devicetree@...r.kernel.org>,
        <robh+dt@...nel.org>, Cristian Pop <cristian.pop@...log.com>
Subject: [PATCH v4 2/2] iio:frequency:admv4420.c: Add support for ADMV4420

Add support for K Band Downconverter with Integrated
Fractional-N PLL and VCO.
More info:
https://www.analog.com/en/products/admv4420.html

Signed-off-by: Cristian Pop <cristian.pop@...log.com>
---
 drivers/iio/frequency/Kconfig    |  10 +
 drivers/iio/frequency/Makefile   |   1 +
 drivers/iio/frequency/admv4420.c | 400 +++++++++++++++++++++++++++++++
 3 files changed, 411 insertions(+)
 create mode 100644 drivers/iio/frequency/admv4420.c

diff --git a/drivers/iio/frequency/Kconfig b/drivers/iio/frequency/Kconfig
index b44036f843af..d905214a0be6 100644
--- a/drivers/iio/frequency/Kconfig
+++ b/drivers/iio/frequency/Kconfig
@@ -60,6 +60,16 @@ config ADMV1013
 	  To compile this driver as a module, choose M here: the
 	  module will be called admv1013.
 
+config ADMV4420
+       tristate "Analog Devices ADMV4420 K Band Downconverter"
+       depends on SPI
+       help
+         Say yes here to build support for Analog Devices K Band
+         Downconverter with integrated Fractional-N PLL and VCO.
+
+         To compile this driver as a module, choose M here: the
+         module will be called admv4420.
+
 config ADRF6780
         tristate "Analog Devices ADRF6780 Microwave Upconverter"
         depends on SPI
diff --git a/drivers/iio/frequency/Makefile b/drivers/iio/frequency/Makefile
index ae6899856c99..782e5baa1630 100644
--- a/drivers/iio/frequency/Makefile
+++ b/drivers/iio/frequency/Makefile
@@ -8,4 +8,5 @@ obj-$(CONFIG_AD9523) += ad9523.o
 obj-$(CONFIG_ADF4350) += adf4350.o
 obj-$(CONFIG_ADF4371) += adf4371.o
 obj-$(CONFIG_ADMV1013) += admv1013.o
+obj-$(CONFIG_ADMV4420) += admv4420.o
 obj-$(CONFIG_ADRF6780) += adrf6780.o
diff --git a/drivers/iio/frequency/admv4420.c b/drivers/iio/frequency/admv4420.c
new file mode 100644
index 000000000000..b4579505372e
--- /dev/null
+++ b/drivers/iio/frequency/admv4420.c
@@ -0,0 +1,400 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * ADMV4420
+ *
+ * Copyright 2021 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/units.h>
+
+#include <asm/unaligned.h>
+
+/* ADMV4420 Register Map */
+#define ADMV4420_SPI_CONFIG_1			0x00
+#define ADMV4420_SPI_CONFIG_2			0x01
+#define ADMV4420_CHIPTYPE			0x03
+#define ADMV4420_PRODUCT_ID_L			0x04
+#define ADMV4420_PRODUCT_ID_H			0x05
+#define ADMV4420_SCRATCHPAD			0x0A
+#define ADMV4420_SPI_REV			0x0B
+#define ADMV4420_ENABLES			0x103
+#define ADMV4420_SDO_LEVEL			0x108
+#define ADMV4420_INT_L				0x200
+#define ADMV4420_INT_H				0x201
+#define ADMV4420_FRAC_L				0x202
+#define ADMV4420_FRAC_M				0x203
+#define ADMV4420_FRAC_H				0x204
+#define ADMV4420_MOD_L				0x208
+#define ADMV4420_MOD_M				0x209
+#define ADMV4420_MOD_H				0x20A
+#define ADMV4420_R_DIV_L			0x20C
+#define ADMV4420_R_DIV_H			0x20D
+#define ADMV4420_REFERENCE			0x20E
+#define ADMV4420_VCO_DATA_READBACK1		0x211
+#define ADMV4420_VCO_DATA_READBACK2		0x212
+#define ADMV4420_PLL_MUX_SEL			0x213
+#define ADMV4420_LOCK_DETECT			0x214
+#define ADMV4420_BAND_SELECT			0x215
+#define ADMV4420_VCO_ALC_TIMEOUT		0x216
+#define ADMV4420_VCO_MANUAL			0x217
+#define ADMV4420_ALC				0x219
+#define ADMV4420_VCO_TIMEOUT1			0x21C
+#define ADMV4420_VCO_TIMEOUT2			0x21D
+#define ADMV4420_VCO_BAND_DIV			0x21E
+#define ADMV4420_VCO_READBACK_SEL		0x21F
+#define ADMV4420_AUTOCAL			0x226
+#define ADMV4420_CP_STATE			0x22C
+#define ADMV4420_CP_BLEED_EN			0x22D
+#define ADMV4420_CP_CURRENT			0x22E
+#define ADMV4420_CP_BLEED			0x22F
+
+#define ADMV4420_SPI_CONFIG_1_SDOACTIVE		(BIT(4) | BIT(3))
+#define ADMV4420_SPI_CONFIG_1_ENDIAN		(BIT(5) | BIT(2))
+#define ADMV4420_SPI_CONFIG_1_SOFTRESET		(BIT(7) | BIT(1))
+
+#define ADMV4420_REFERENCE_DIVIDE_BY_2_MASK	BIT(0)
+#define ADMV4420_REFERENCE_MODE_MASK		BIT(1)
+#define ADMV4420_REFERENCE_IN_MODE(x)		FIELD_PREP(ADMV4420_REFERENCE_MODE_MASK, x)
+#define ADMV4420_REFERENCE_DOUBLER_MASK		BIT(2)
+#define ADMV4420_REFERENCE_DOUBLER(x)		FIELD_PREP(ADMV4420_REFERENCE_DOUBLER_MASK, x)
+
+#define ADMV4420_REF_DIVIDER_MAX_VAL		GENMASK(9, 0)
+#define ADMV4420_N_COUNTER_INT_MAX		GENMASK(15, 0)
+#define ADMV4420_N_COUNTER_FRAC_MAX		GENMASK(23, 0)
+#define ADMV4420_N_COUNTER_MOD_MAX		GENMASK(23, 0)
+
+#define ENABLE_PLL				BIT(6)
+#define ENABLE_LO				BIT(5)
+#define ENABLE_VCO				BIT(3)
+#define ENABLE_IFAMP				BIT(2)
+#define ENABLE_MIXER				BIT(1)
+#define ENABLE_LNA				BIT(0)
+
+#define ADMV4420_SCRATCH_PAD_VAL_1              0xAD
+#define ADMV4420_SCRATCH_PAD_VAL_2              0xEA
+
+#define ADMV4420_REF_FREQ_HZ                    50000000
+#define MAX_N_COUNTER                           655360UL
+#define MAX_R_DIVIDER                           1024
+#define ADMV4420_DEFAULT_LO_FREQ_HZ		16750000000ULL
+
+enum admv4420_mux_sel {
+	ADMV4420_LOW = 0,
+	ADMV4420_LOCK_DTCT = 1,
+	ADMV4420_R_COUNTER_PER_2 = 4,
+	ADMV4420_N_CONUTER_PER_2 = 5,
+	ADMV4420_HIGH = 8,
+};
+
+struct admv4420_reference_block {
+	bool doubler_en;
+	bool divide_by_2_en;
+	bool ref_single_ended;
+	u32 divider;
+};
+
+struct admv4420_n_counter {
+	u32 int_val;
+	u32 frac_val;
+	u32 mod_val;
+	u32 n_counter;
+};
+
+struct admv4420_state {
+	struct spi_device		*spi;
+	struct regmap			*regmap;
+	u64				vco_freq_hz;
+	u64				lo_freq_hz;
+	struct admv4420_reference_block ref_block;
+	struct admv4420_n_counter	n_counter;
+	enum admv4420_mux_sel		mux_sel;
+	struct mutex			lock;
+	u8				transf_buf[4] ____cacheline_aligned;
+};
+
+static const struct regmap_config admv4420_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.read_flag_mask = BIT(7),
+};
+
+static int admv4420_reg_access(struct iio_dev *indio_dev,
+			       u32 reg, u32 writeval,
+			       u32 *readval)
+{
+	struct admv4420_state *st = iio_priv(indio_dev);
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+	else
+		return regmap_write(st->regmap, reg, writeval);
+}
+
+static int admv4420_set_n_counter(struct admv4420_state *st, u32 int_val,
+				  u32 frac_val, u32 mod_val)
+{
+	int ret;
+
+	put_unaligned_le32(frac_val, st->transf_buf);
+	ret = regmap_bulk_write(st->regmap, ADMV4420_FRAC_L, st->transf_buf, 3);
+	if (ret)
+		return ret;
+
+	put_unaligned_le32(mod_val, st->transf_buf);
+	ret = regmap_bulk_write(st->regmap, ADMV4420_MOD_L, st->transf_buf, 3);
+	if (ret)
+		return ret;
+
+	put_unaligned_le32(int_val, st->transf_buf);
+	return regmap_bulk_write(st->regmap, ADMV4420_INT_L, st->transf_buf, 2);
+}
+
+static int admv4420_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long info)
+{
+	struct admv4420_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_FREQUENCY:
+
+		*val = div_u64_rem(st->lo_freq_hz, MICRO, val2);
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info admv4420_info = {
+	.read_raw = admv4420_read_raw,
+	.debugfs_reg_access = &admv4420_reg_access,
+};
+
+static const struct iio_chan_spec admv4420_channels[] = {
+	{
+		.type = IIO_ALTVOLTAGE,
+		.output = 0,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_FREQUENCY),
+	},
+};
+
+static void admv4420_fw_parse(struct admv4420_state *st)
+{
+	struct fwnode_handle *fwnode = dev_fwnode(&st->spi->dev);
+	u32 tmp;
+	int ret;
+
+	ret = fwnode_property_read_u32(fwnode, "adi,lo-freq-khz", &tmp);
+	if (!ret)
+		st->lo_freq_hz = (u64)tmp * KILO;
+
+	st->ref_block.ref_single_ended = fwnode_property_read_bool(fwnode,
+								   "adi,ref-ext-single-ended-en");
+}
+
+static inline uint64_t admv4420_calc_pfd_vco(struct admv4420_state *st)
+{
+	return div_u64(st->vco_freq_hz * 10, st->n_counter.n_counter);
+}
+
+static inline uint32_t admv4420_calc_pfd_ref(struct admv4420_state *st)
+{
+	uint32_t tmp;
+	u8 doubler, divide_by_2;
+
+	doubler = st->ref_block.doubler_en ? 2 : 1;
+	divide_by_2 = st->ref_block.divide_by_2_en ? 2 : 1;
+	tmp = ADMV4420_REF_FREQ_HZ * doubler;
+
+	return (tmp / (st->ref_block.divider * divide_by_2));
+}
+
+static int admv4420_calc_parameters(struct admv4420_state *st)
+{
+	u64 pfd_ref, pfd_vco;
+	bool sol_found = false;
+
+	st->ref_block.doubler_en = false;
+	st->ref_block.divide_by_2_en = false;
+	st->vco_freq_hz = div_u64(st->lo_freq_hz, 2);
+
+	for (st->ref_block.divider = 1; st->ref_block.divider < MAX_R_DIVIDER;
+	    st->ref_block.divider++) {
+		pfd_ref = admv4420_calc_pfd_ref(st);
+		for (st->n_counter.n_counter = 1; st->n_counter.n_counter < MAX_N_COUNTER;
+		    st->n_counter.n_counter++) {
+			pfd_vco = admv4420_calc_pfd_vco(st);
+			if (pfd_ref == pfd_vco) {
+				sol_found = true;
+				break;
+			}
+		}
+
+		if (sol_found)
+			break;
+
+		st->n_counter.n_counter = 1;
+	}
+	if (!sol_found)
+		return -1;
+
+	st->n_counter.int_val = div_u64_rem(st->n_counter.n_counter, 10, &st->n_counter.frac_val);
+	st->n_counter.mod_val = 10;
+
+	return 0;
+}
+
+static int admv4420_setup(struct iio_dev *indio_dev)
+{
+	struct admv4420_state *st = iio_priv(indio_dev);
+	struct device *dev = indio_dev->dev.parent;
+	u32 val;
+	int ret;
+
+	ret = regmap_write(st->regmap, ADMV4420_SPI_CONFIG_1,
+			   ADMV4420_SPI_CONFIG_1_SOFTRESET);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, ADMV4420_SPI_CONFIG_1,
+			   ADMV4420_SPI_CONFIG_1_SDOACTIVE |
+			   ADMV4420_SPI_CONFIG_1_ENDIAN);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap,
+			   ADMV4420_SCRATCHPAD,
+			   ADMV4420_SCRATCH_PAD_VAL_1);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, ADMV4420_SCRATCHPAD, &val);
+	if (ret)
+		return ret;
+
+	if (val != ADMV4420_SCRATCH_PAD_VAL_1) {
+		dev_err(dev, "Failed ADMV4420 to read/write scratchpad %x ", val);
+		return -EIO;
+	}
+
+	ret = regmap_write(st->regmap,
+			   ADMV4420_SCRATCHPAD,
+			   ADMV4420_SCRATCH_PAD_VAL_2);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, ADMV4420_SCRATCHPAD, &val);
+	if (ret)
+		return ret;
+
+	if (val != ADMV4420_SCRATCH_PAD_VAL_2) {
+		dev_err(dev, "Failed to read/write scratchpad %x ", val);
+		return -EIO;
+	}
+
+	st->mux_sel = ADMV4420_LOCK_DTCT;
+	st->lo_freq_hz = ADMV4420_DEFAULT_LO_FREQ_HZ;
+
+	admv4420_fw_parse(st);
+
+	ret = admv4420_calc_parameters(st);
+	if (ret) {
+		dev_err(dev, "Failed calc parameters for %lld ", st->vco_freq_hz);
+		return ret;
+	}
+
+	ret = regmap_write(st->regmap, ADMV4420_R_DIV_L,
+			   FIELD_GET(0xFF, st->ref_block.divider));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, ADMV4420_R_DIV_H,
+			   FIELD_GET(0xFF00, st->ref_block.divider));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, ADMV4420_REFERENCE,
+			   st->ref_block.divide_by_2_en |
+			   ADMV4420_REFERENCE_IN_MODE(st->ref_block.ref_single_ended) |
+			   ADMV4420_REFERENCE_DOUBLER(st->ref_block.doubler_en));
+	if (ret)
+		return ret;
+
+	ret = admv4420_set_n_counter(st, st->n_counter.int_val,
+				     st->n_counter.frac_val,
+				     st->n_counter.mod_val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, ADMV4420_PLL_MUX_SEL, st->mux_sel);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, ADMV4420_ENABLES,
+			    ENABLE_PLL | ENABLE_LO | ENABLE_VCO |
+			    ENABLE_IFAMP | ENABLE_MIXER | ENABLE_LNA);
+}
+
+static int admv4420_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct admv4420_state *st;
+	struct regmap *regmap;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_spi(spi, &admv4420_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(&spi->dev, PTR_ERR(regmap),
+				     "Failed to initializing spi regmap\n");
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+	st->regmap = regmap;
+
+	indio_dev->name = "admv4420";
+	indio_dev->info = &admv4420_info;
+	indio_dev->channels = admv4420_channels;
+	indio_dev->num_channels = ARRAY_SIZE(admv4420_channels);
+
+	ret = admv4420_setup(indio_dev);
+	if (ret) {
+		dev_err(&spi->dev, "Setup ADMV4420 failed (%d)\n", ret);
+		return ret;
+	}
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct of_device_id admv4420_of_match[] = {
+	{ .compatible = "adi,admv4420" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, admv4420_of_match);
+
+static struct spi_driver admv4420_driver = {
+	.driver = {
+		.name = "admv4420",
+		.of_match_table = admv4420_of_match,
+	},
+	.probe = admv4420_probe,
+};
+
+module_spi_driver(admv4420_driver);
+
+MODULE_AUTHOR("Cristian Pop <cristian.pop@...log.com>");
+MODULE_DESCRIPTION("Analog Devices ADMV44200 K Band Downconverter");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.17.1

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