Message-ID: <20241018104210.51659-6-antoniu.miclaus@analog.com>
Date: Fri, 18 Oct 2024 13:42:10 +0300
From: Antoniu Miclaus <antoniu.miclaus@...log.com>
To: <jic23@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <nuno.sa@...log.com>, <conor+dt@...nel.org>, <ukleinek@...nel.org>,
        <dragos.bogdan@...log.com>, <linux-iio@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pwm@...r.kernel.org>
CC: Antoniu Miclaus <antoniu.miclaus@...log.com>
Subject: [PATCH v4 6/6] iio: adc: ad4851: add ad485x driver

Add support for the AD485X a fully buffered, 8-channel simultaneous
sampling, 16/20-bit, 1 MSPS data acquisition system (DAS) with
differential, wide common-mode range inputs.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
---
changes in v4:
 - shrink ad4851_oversampling_ratios into 8 per line.
 - add osr 0 case in ad4851_set_oversampling_ratio
 - use if..else statement for setting packet format 
 - add comment inside "ad4851_find_opt"
 - use ROUND_CLOSEST
 - use NSEC_PER_SEC 
 - change the handling of regulators vrefbuf and vrefio and update afferent
   registers
 - {} -> { }
 - fix compatible strings order.
 drivers/iio/adc/Kconfig  |   13 +
 drivers/iio/adc/Makefile |    1 +
 drivers/iio/adc/ad4851.c | 1155 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 1169 insertions(+)
 create mode 100644 drivers/iio/adc/ad4851.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index f60fe85a30d5..93e53794ce89 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -36,6 +36,19 @@ config AD4130
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad4130.
 
+config AD4851
+	tristate "Analog Device AD4851 DAS Driver"
+	depends on SPI
+	select REGMAP_SPI
+	select IIO_BACKEND
+	help
+	  Say yes here to build support for Analog Devices AD4851, AD4852,
+	  AD4853, AD4854, AD4855, AD4856, AD4857, AD4858, AD4858I high speed
+	  data acquisition system (DAS).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad4851.
+
 config AD7091R
 	tristate
 
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d370e066544e..1a873bf1a917 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -7,6 +7,7 @@
 obj-$(CONFIG_AB8500_GPADC) += ab8500-gpadc.o
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
 obj-$(CONFIG_AD4130) += ad4130.o
+obj-$(CONFIG_AD4851) += ad4851.o
 obj-$(CONFIG_AD7091R) += ad7091r-base.o
 obj-$(CONFIG_AD7091R5) += ad7091r5.o
 obj-$(CONFIG_AD7091R8) += ad7091r8.o
diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
new file mode 100644
index 000000000000..65aa434b535f
--- /dev/null
+++ b/drivers/iio/adc/ad4851.c
@@ -0,0 +1,1155 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices AD4851 DAS driver
+ *
+ * Copyright 2024 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/minmax.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
+
+#include <asm/unaligned.h>
+
+#define AD4851_REG_INTERFACE_CONFIG_A	0x00
+#define AD4851_REG_INTERFACE_CONFIG_B	0x01
+#define AD4851_REG_PRODUCT_ID_L		0x04
+#define AD4851_REG_PRODUCT_ID_H		0x05
+#define AD4851_REG_DEVICE_CTRL		0x25
+#define AD4851_REG_PACKET		0x26
+#define AD4851_REG_OVERSAMPLE		0x27
+
+#define AD4851_REG_CH_CONFIG_BASE	0x2A
+#define AD4851_REG_CHX_SOFTSPAN(ch)	((0x12 * (ch)) + AD4851_REG_CH_CONFIG_BASE)
+#define AD4851_REG_CHX_OFFSET(ch)	(AD4851_REG_CHX_SOFTSPAN(ch) + 0x01)
+#define AD4851_REG_CHX_OFFSET_LSB(ch)	AD4851_REG_CHX_OFFSET(ch)
+#define AD4851_REG_CHX_OFFSET_MID(ch)	(AD4851_REG_CHX_OFFSET_LSB(ch) + 0x01)
+#define AD4851_REG_CHX_OFFSET_MSB(ch)	(AD4851_REG_CHX_OFFSET_MID(ch) + 0x01)
+#define AD4851_REG_CHX_GAIN(ch)		(AD4851_REG_CHX_OFFSET(ch) + 0x03)
+#define AD4851_REG_CHX_GAIN_LSB(ch)	AD4851_REG_CHX_GAIN(ch)
+#define AD4851_REG_CHX_GAIN_MSB(ch)	(AD4851_REG_CHX_GAIN(ch) + 0x01)
+#define AD4851_REG_CHX_PHASE(ch)	(AD4851_REG_CHX_GAIN(ch) + 0x02)
+#define AD4851_REG_CHX_PHASE_LSB(ch)	AD4851_REG_CHX_PHASE(ch)
+#define AD4851_REG_CHX_PHASE_MSB(ch)	(AD4851_REG_CHX_PHASE_LSB(ch) + 0x01)
+
+#define AD4851_REG_TESTPAT_0(c)		(0x38 + (c) * 0x12)
+#define AD4851_REG_TESTPAT_1(c)		(0x39 + (c) * 0x12)
+#define AD4851_REG_TESTPAT_2(c)		(0x3A + (c) * 0x12)
+#define AD4851_REG_TESTPAT_3(c)		(0x3B + (c) * 0x12)
+
+#define AD4851_SW_RESET			(BIT(7) | BIT(0))
+#define AD4851_SDO_ENABLE		BIT(4)
+#define AD4851_SINGLE_INSTRUCTION	BIT(7)
+#define AD4851_REFBUF_PD		BIT(2)
+#define AD4851_REFSEL_PD		BIT(1)
+#define AD4851_ECHO_CLOCK_MODE		BIT(0)
+
+#define AD4851_PACKET_FORMAT_0		0
+#define AD4851_PACKET_FORMAT_1		1
+#define AD4851_PACKET_FORMAT_MASK	GENMASK(1, 0)
+
+#define AD4851_OS_EN_MSK		BIT(7)
+#define AD4851_OS_RATIO_MSK		GENMASK(3, 0)
+
+#define AD4851_TEST_PAT			BIT(2)
+
+#define AD4858_PACKET_SIZE_20		0
+#define AD4858_PACKET_SIZE_24		1
+#define AD4858_PACKET_SIZE_32		2
+
+#define AD4857_PACKET_SIZE_16		0
+#define AD4857_PACKET_SIZE_24		1
+
+#define AD4851_TESTPAT_0_DEFAULT	0x2A
+#define AD4851_TESTPAT_1_DEFAULT	0x3C
+#define AD4851_TESTPAT_2_DEFAULT	0xCE
+#define AD4851_TESTPAT_3_DEFAULT(c)	(0x0A + (0x10 * (c)))
+
+#define AD4851_SOFTSPAN_0V_2V5		0
+#define AD4851_SOFTSPAN_N2V5_2V5	1
+#define AD4851_SOFTSPAN_0V_5V		2
+#define AD4851_SOFTSPAN_N5V_5V		3
+#define AD4851_SOFTSPAN_0V_6V25		4
+#define AD4851_SOFTSPAN_N6V25_6V25	5
+#define AD4851_SOFTSPAN_0V_10V		6
+#define AD4851_SOFTSPAN_N10V_10V	7
+#define AD4851_SOFTSPAN_0V_12V5		8
+#define AD4851_SOFTSPAN_N12V5_12V5	9
+#define AD4851_SOFTSPAN_0V_20V		10
+#define AD4851_SOFTSPAN_N20V_20V	11
+#define AD4851_SOFTSPAN_0V_25V		12
+#define AD4851_SOFTSPAN_N25V_25V	13
+#define AD4851_SOFTSPAN_0V_40V		14
+#define AD4851_SOFTSPAN_N40V_40V	15
+
+#define AD4851_MAX_LANES		8
+#define AD4851_MAX_IODELAY		32
+
+#define AD4851_T_CNVH_NS		40
+
+struct ad4851_chip_info {
+	const char *name;
+	unsigned int product_id;
+	const unsigned int (*scale_table)[2];
+	int num_scales;
+	const int *offset_table;
+	int num_offset;
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+	unsigned long throughput;
+	unsigned int resolution;
+};
+
+struct ad4851_state {
+	struct spi_device *spi;
+	struct pwm_device *cnv;
+	struct iio_backend *back;
+	/*
+	 * Synchronize access to members the of driver state, and ensure
+	 * atomicity of consecutive regmap operations.
+	 */
+	struct mutex lock;
+	struct regmap *regmap;
+	struct regulator *vrefbuf;
+	struct regulator *vrefio;
+	const struct ad4851_chip_info *info;
+	struct gpio_desc *pd_gpio;
+	unsigned long sampling_freq;
+	unsigned int (*scales)[2];
+	int *offsets;
+};
+
+static int ad4851_reg_access(struct iio_dev *indio_dev,
+			     unsigned int reg,
+			     unsigned int writeval,
+			     unsigned int *readval)
+{
+	struct ad4851_state *st = iio_priv(indio_dev);
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+
+	return regmap_write(st->regmap, reg, writeval);
+}
+
+static int ad4851_set_sampling_freq(struct ad4851_state *st, unsigned int freq)
+{
+	struct pwm_state cnv_state = {
+		.duty_cycle = AD4851_T_CNVH_NS,
+		.enabled = true,
+	};
+	int ret;
+
+	freq = clamp(freq, 1, st->info->throughput);
+
+	cnv_state.period = DIV_ROUND_DOWN_ULL(NSEC_PER_SEC, freq);
+
+	ret = pwm_apply_might_sleep(st->cnv, &cnv_state);
+	if (ret)
+		return ret;
+
+	st->sampling_freq = freq;
+
+	return 0;
+}
+
+static const int ad4851_oversampling_ratios[] = {
+	1, 2, 4, 8, 16,	32, 64, 128,
+	256, 512, 1024, 2048, 4096, 8192, 16384, 32768,
+	65536,
+};
+
+static int ad4851_osr_to_regval(int ratio)
+{
+	int i;
+
+	for (i = 1; i < ARRAY_SIZE(ad4851_oversampling_ratios); i++)
+		if (ratio == ad4851_oversampling_ratios[i])
+			return i - 1;
+
+	return -EINVAL;
+}
+
+static int ad4851_set_oversampling_ratio(struct ad4851_state *st,
+					 const struct iio_chan_spec *chan,
+					 unsigned int osr)
+{
+	unsigned int val;
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	if (osr == 1) {
+		ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
+					 AD4851_OS_EN_MSK, 0);
+		if (ret)
+			return ret;
+	} else {
+		ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
+					 AD4851_OS_EN_MSK, AD4851_OS_EN_MSK);
+		if (ret)
+			return ret;
+
+		val = ad4851_osr_to_regval(osr);
+		if (val < 0)
+			return -EINVAL;
+
+		ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
+					 AD4851_OS_RATIO_MSK, val);
+		if (ret)
+			return ret;
+	}
+
+	switch (chan->scan_type.realbits) {
+	case 20:
+		switch (osr) {
+		case 0:
+			return -EINVAL;
+		case 1:
+			val = 20;
+			break;
+		default:
+			val = 24;
+			break;
+		}
+		break;
+	case 16:
+		val = 16;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = iio_backend_data_size_set(st->back, val);
+	if (ret)
+		return ret;
+
+	if (osr == 1)
+		return regmap_update_bits(st->regmap, AD4851_REG_PACKET,
+					  AD4851_PACKET_FORMAT_MASK, 0);
+
+	return regmap_update_bits(st->regmap, AD4851_REG_PACKET,
+				  AD4851_PACKET_FORMAT_MASK, 1);
+}
+
+static int ad4851_get_oversampling_ratio(struct ad4851_state *st, unsigned int *val)
+{
+	unsigned int osr;
+	int ret;
+
+	ret = regmap_read(st->regmap, AD4851_REG_OVERSAMPLE, &osr);
+	if (ret)
+		return ret;
+
+	if (!FIELD_GET(AD4851_OS_EN_MSK, osr))
+		*val = 1;
+	else
+		*val = ad4851_oversampling_ratios[FIELD_GET(AD4851_OS_RATIO_MSK, osr)];
+
+	return IIO_VAL_INT;
+}
+
+static void ad4851_reg_disable(void *data)
+{
+	regulator_disable(data);
+}
+
+static int ad4851_setup(struct ad4851_state *st)
+{
+	unsigned int product_id;
+	int ret;
+
+	if (!IS_ERR(st->vrefbuf)) {
+		ret = regmap_update_bits(st->regmap, AD4851_REG_DEVICE_CTRL,
+					 AD4851_REFBUF_PD, AD4851_REFBUF_PD);
+		if (ret)
+			return ret;
+
+		ret = regulator_enable(st->vrefbuf);
+		if (ret)
+			return ret;
+
+		ret = devm_add_action_or_reset(&st->spi->dev, ad4851_reg_disable,
+					       st->vrefbuf);
+		if (ret)
+			return ret;
+	}
+
+	if (!IS_ERR(st->vrefio)) {
+		ret = regmap_update_bits(st->regmap, AD4851_REG_DEVICE_CTRL,
+					 AD4851_REFSEL_PD, AD4851_REFSEL_PD);
+		if (ret)
+			return ret;
+
+		ret = regulator_enable(st->vrefio);
+		if (ret)
+			return ret;
+
+		ret = devm_add_action_or_reset(&st->spi->dev, ad4851_reg_disable,
+					       st->vrefio);
+		if (ret)
+			return ret;
+	}
+
+	ret = ad4851_set_sampling_freq(st, HZ_PER_MHZ);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD4851_REG_INTERFACE_CONFIG_A,
+			   AD4851_SW_RESET);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD4851_REG_INTERFACE_CONFIG_B,
+			   AD4851_SINGLE_INSTRUCTION);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD4851_REG_INTERFACE_CONFIG_A,
+			   AD4851_SDO_ENABLE);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD4851_REG_PRODUCT_ID_L, &product_id);
+	if (ret)
+		return ret;
+
+	if (product_id != st->info->product_id)
+		dev_info(&st->spi->dev, "Unknown product ID: 0x%02X\n",
+			 product_id);
+
+	ret = regmap_write(st->regmap, AD4851_REG_DEVICE_CTRL,
+			   AD4851_ECHO_CLOCK_MODE);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, AD4851_REG_PACKET, 0);
+}
+
+static int ad4851_find_opt(bool *field, u32 size, u32 *ret_start)
+{
+	unsigned int i, cnt = 0, max_cnt = 0, max_start = 0;
+	int start;
+
+	for (i = 0, start = -1; i < size; i++) {
+		if (field[i] == 0) {
+			if (start == -1)
+				start = i;
+			cnt++;
+		} else {
+			if (cnt > max_cnt) {
+				max_cnt = cnt;
+				max_start = start;
+			}
+			start = -1;
+			cnt = 0;
+		}
+	}
+	/*
+	 * Find the longest consecutive sequence of false values from field
+	 * and return starting index.
+	 */
+	if (cnt > max_cnt) {
+		max_cnt = cnt;
+		max_start = start;
+	}
+
+	if (!max_cnt)
+		return -ENOENT;
+
+	*ret_start = max_start;
+
+	return max_cnt;
+}
+
+static int ad4851_calibrate(struct ad4851_state *st)
+{
+	unsigned int opt_delay, lane_num, delay, i, s, c;
+	enum iio_backend_interface_type interface_type;
+	DECLARE_BITMAP(pn_status, AD4851_MAX_LANES * AD4851_MAX_IODELAY);
+	bool status;
+	int ret;
+
+	ret = iio_backend_interface_type_get(st->back, &interface_type);
+	if (ret)
+		return ret;
+
+	switch (interface_type) {
+	case IIO_BACKEND_INTERFACE_CMOS:
+		lane_num = st->info->num_channels;
+		break;
+	case IIO_BACKEND_INTERFACE_LVDS:
+		lane_num = 1;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (st->info->resolution == 16) {
+		ret = iio_backend_data_size_set(st->back, 24);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD4851_REG_PACKET,
+				   AD4851_TEST_PAT | AD4857_PACKET_SIZE_24);
+		if (ret)
+			return ret;
+	} else {
+		ret = iio_backend_data_size_set(st->back, 32);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD4851_REG_PACKET,
+				   AD4851_TEST_PAT | AD4858_PACKET_SIZE_32);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < st->info->num_channels; i++) {
+		ret = regmap_write(st->regmap, AD4851_REG_TESTPAT_0(i),
+				   AD4851_TESTPAT_0_DEFAULT);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD4851_REG_TESTPAT_1(i),
+				   AD4851_TESTPAT_1_DEFAULT);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD4851_REG_TESTPAT_2(i),
+				   AD4851_TESTPAT_2_DEFAULT);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD4851_REG_TESTPAT_3(i),
+				   AD4851_TESTPAT_3_DEFAULT(i));
+		if (ret)
+			return ret;
+
+		ret = iio_backend_chan_enable(st->back, i);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < lane_num; i++) {
+		for (delay = 0; delay < AD4851_MAX_IODELAY; delay++) {
+			ret = iio_backend_iodelay_set(st->back, i, delay);
+			if (ret)
+				return ret;
+			ret = iio_backend_chan_status(st->back, i, &status);
+			if (ret)
+				return ret;
+
+			if (status)
+				set_bit(i * AD4851_MAX_IODELAY + delay, pn_status);
+			else
+				clear_bit(i * AD4851_MAX_IODELAY + delay, pn_status);
+		}
+	}
+
+	for (i = 0; i < lane_num; i++) {
+		status = test_bit(i * AD4851_MAX_IODELAY, pn_status);
+		c = ad4851_find_opt(&status, AD4851_MAX_IODELAY, &s);
+		if (c < 0)
+			return c;
+
+		opt_delay = s + c / 2;
+		ret = iio_backend_iodelay_set(st->back, i, opt_delay);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < st->info->num_channels; i++) {
+		ret = iio_backend_chan_disable(st->back, i);
+		if (ret)
+			return ret;
+	}
+
+	ret = iio_backend_data_size_set(st->back, 20);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, AD4851_REG_PACKET, 0);
+}
+
+static int ad4851_get_calibscale(struct ad4851_state *st, int ch, int *val, int *val2)
+{
+	unsigned int reg_val;
+	int gain;
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_GAIN_MSB(ch),
+			  &reg_val);
+	if (ret)
+		return ret;
+
+	gain = (reg_val & 0xFF) << 8;
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_GAIN_LSB(ch),
+			  &reg_val);
+	if (ret)
+		return ret;
+
+	gain |= reg_val & 0xFF;
+
+	*val = gain;
+	*val2 = 32768;
+
+	return IIO_VAL_FRACTIONAL;
+}
+
+static int ad4851_set_calibscale(struct ad4851_state *st, int ch, int val,
+				 int val2)
+{
+	u64 gain;
+	u8 buf[0];
+	int ret;
+
+	if (val < 0 || val2 < 0)
+		return -EINVAL;
+
+	gain = val * MICRO + val2;
+	gain = DIV_U64_ROUND_CLOSEST(gain * 32768, MICRO);
+
+	put_unaligned_be16(gain, buf);
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_write(st->regmap, AD4851_REG_CHX_GAIN_MSB(ch),
+			   buf[0]);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, AD4851_REG_CHX_GAIN_LSB(ch),
+			    buf[1]);
+}
+
+static int ad4851_get_calibbias(struct ad4851_state *st, int ch, int *val)
+{
+	unsigned int lsb, mid, msb;
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_OFFSET_MSB(ch),
+			  &msb);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_OFFSET_MID(ch),
+			  &mid);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_OFFSET_LSB(ch),
+			  &lsb);
+	if (ret)
+		return ret;
+
+	if (st->info->resolution == 16) {
+		*val = msb << 8;
+		*val |= mid;
+		*val = sign_extend32(*val, 15);
+	} else {
+		*val = msb << 12;
+		*val |= mid << 4;
+		*val |= lsb >> 4;
+		*val = sign_extend32(*val, 19);
+	}
+
+	return IIO_VAL_INT;
+}
+
+static int ad4851_set_calibbias(struct ad4851_state *st, int ch, int val)
+{
+	u8 buf[3] = { 0 };
+	int ret;
+
+	if (val < 0)
+		return -EINVAL;
+
+	if (st->info->resolution == 16)
+		put_unaligned_be16(val, buf);
+	else
+		put_unaligned_be24(val << 4, buf);
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_write(st->regmap, AD4851_REG_CHX_OFFSET_LSB(ch), buf[2]);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD4851_REG_CHX_OFFSET_MID(ch), buf[1]);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, AD4851_REG_CHX_OFFSET_MSB(ch), buf[0]);
+}
+
+static const unsigned int ad4851_scale_table[][2] = {
+	{ 2500, 0x0 },
+	{ 5000, 0x1 },
+	{ 5000, 0x2 },
+	{ 10000, 0x3 },
+	{ 6250, 0x04 },
+	{ 12500, 0x5 },
+	{ 10000, 0x6 },
+	{ 20000, 0x7 },
+	{ 12500, 0x8 },
+	{ 25000, 0x9 },
+	{ 20000, 0xA },
+	{ 40000, 0xB },
+	{ 25000, 0xC },
+	{ 50000, 0xD },
+	{ 40000, 0xE },
+	{ 80000, 0xF },
+};
+
+static const int ad4857_offset_table[] = {
+	0, -32768,
+};
+
+static const int ad4858_offset_table[] = {
+	0, -524288,
+};
+
+static const unsigned int ad4851_scale_avail[] = {
+	2500, 5000,
+	10000, 6250,
+	12500, 20000,
+	25000, 40000,
+	50000, 80000,
+};
+
+static void __ad4851_get_scale(struct ad4851_state *st, int scale_tbl,
+			       unsigned int *val, unsigned int *val2)
+{
+	const struct ad4851_chip_info *info = st->info;
+	const struct iio_chan_spec *chan = &info->channels[0];
+	unsigned int tmp;
+
+	tmp = ((unsigned long long)scale_tbl * MICRO) >> chan->scan_type.realbits;
+	*val = tmp / MICRO;
+	*val2 = tmp % MICRO;
+}
+
+static int ad4851_set_scale(struct ad4851_state *st,
+			    const struct iio_chan_spec *chan, int val, int val2)
+{
+	unsigned int scale_val[2];
+	unsigned int i;
+	bool single_ended = false;
+
+	for (i = 0; i < ARRAY_SIZE(ad4851_scale_table); i++) {
+		__ad4851_get_scale(st, ad4851_scale_table[i][0],
+				   &scale_val[0], &scale_val[1]);
+		if (scale_val[0] != val || scale_val[1] != val2)
+			continue;
+
+		/*
+		 * Adjust the softspan value (differential or single ended)
+		 * based on the scale value selected and current offset of
+		 * the channel.
+		 *
+		 * If the offset is 0 then continue iterations until finding
+		 * the next matching scale value which always corresponds to
+		 * the single ended mode.
+		 */
+		if (!st->offsets[chan->channel] && !single_ended) {
+			single_ended = true;
+			continue;
+		}
+
+		return regmap_write(st->regmap,
+				    AD4851_REG_CHX_SOFTSPAN(chan->channel),
+				    ad4851_scale_table[i][1]);
+	}
+
+	return -EINVAL;
+}
+
+static int ad4851_get_scale(struct ad4851_state *st,
+			    const struct iio_chan_spec *chan, int *val,
+			    int *val2)
+{
+	unsigned int i, softspan_val;
+	int ret;
+
+	ret = regmap_read(st->regmap, AD4851_REG_CHX_SOFTSPAN(chan->channel),
+			  &softspan_val);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(ad4851_scale_table); i++) {
+		if (softspan_val == ad4851_scale_table[i][1])
+			break;
+	}
+
+	if (i == ARRAY_SIZE(ad4851_scale_table))
+		return -EIO;
+
+	__ad4851_get_scale(st, ad4851_scale_table[i][0], val, val2);
+
+	return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int ad4851_set_offset(struct ad4851_state *st,
+			     const struct iio_chan_spec *chan, int val)
+{
+	guard(mutex)(&st->lock);
+
+	if (val != st->offsets[chan->channel])
+		return 0;
+
+	st->offsets[chan->channel] = val;
+	/* Restore to the default range if offset changes */
+	if (st->offsets[chan->channel])
+		return regmap_write(st->regmap,
+					AD4851_REG_CHX_SOFTSPAN(chan->channel),
+					AD4851_SOFTSPAN_N40V_40V);
+	return regmap_write(st->regmap,
+				AD4851_REG_CHX_SOFTSPAN(chan->channel),
+				AD4851_SOFTSPAN_0V_40V);
+}
+
+static int ad4851_scale_offset_fill(struct ad4851_state *st)
+{
+	unsigned int i, val1, val2;
+
+	st->offsets = devm_kcalloc(&st->spi->dev, st->info->num_channels,
+				   sizeof(*st->offsets), GFP_KERNEL);
+	if (!st->offsets)
+		return -ENOMEM;
+
+	st->scales = devm_kmalloc_array(&st->spi->dev, ARRAY_SIZE(ad4851_scale_avail),
+					sizeof(*st->scales), GFP_KERNEL);
+	if (!st->scales)
+		return -ENOMEM;
+
+	for (i = 0; i < ARRAY_SIZE(ad4851_scale_avail); i++) {
+		__ad4851_get_scale(st, ad4851_scale_avail[i], &val1, &val2);
+		st->scales[i][0] = val1;
+		st->scales[i][1] = val2;
+	}
+
+	return 0;
+}
+
+static int ad4851_read_raw(struct iio_dev *indio_dev,
+			   const struct iio_chan_spec *chan,
+			   int *val, int *val2, long info)
+{
+	struct ad4851_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = st->sampling_freq;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		return ad4851_get_calibscale(st, chan->channel, val, val2);
+	case IIO_CHAN_INFO_SCALE:
+		return ad4851_get_scale(st, chan, val, val2);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return ad4851_get_calibbias(st, chan->channel, val);
+	case IIO_CHAN_INFO_OFFSET:
+		scoped_guard(mutex, &st->lock)
+			*val = st->offsets[chan->channel];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return ad4851_get_oversampling_ratio(st, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad4851_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long info)
+{
+	struct ad4851_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return ad4851_set_sampling_freq(st, val);
+	case IIO_CHAN_INFO_SCALE:
+		return ad4851_set_scale(st, chan, val, val2);
+	case IIO_CHAN_INFO_CALIBSCALE:
+		return ad4851_set_calibscale(st, chan->channel, val, val2);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return ad4851_set_calibbias(st, chan->channel, val);
+	case IIO_CHAN_INFO_OFFSET:
+		return ad4851_set_offset(st, chan, val);
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return ad4851_set_oversampling_ratio(st, chan, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad4851_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad4851_state *st = iio_priv(indio_dev);
+	unsigned int c;
+	int ret;
+
+	for (c = 0; c < st->info->num_channels; c++) {
+		if (test_bit(c, scan_mask))
+			ret = iio_backend_chan_enable(st->back, c);
+		else
+			ret = iio_backend_chan_disable(st->back, c);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int ad4851_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long mask)
+{
+	struct ad4851_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		*vals = (const int *)st->scales;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+		/* Values are stored in a 2D matrix */
+		*length = ARRAY_SIZE(ad4851_scale_avail) * 2;
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_OFFSET:
+		*vals = st->info->offset_table;
+		*type = IIO_VAL_INT;
+		*length = st->info->num_offset;
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = ad4851_oversampling_ratios;
+		*length = ARRAY_SIZE(ad4851_oversampling_ratios);
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+#define AD4851_IIO_CHANNEL(index, real, storage)			\
+{									\
+	.type = IIO_VOLTAGE,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_CALIBSCALE) |		\
+		BIT(IIO_CHAN_INFO_CALIBBIAS) |				\
+		BIT(IIO_CHAN_INFO_SCALE) |				\
+		BIT(IIO_CHAN_INFO_OFFSET),				\
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.info_mask_shared_by_type_available =				\
+		BIT(IIO_CHAN_INFO_SCALE) |				\
+		BIT(IIO_CHAN_INFO_OFFSET) |				\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.indexed = 1,							\
+	.channel = index,						\
+	.scan_index = index,						\
+	.scan_type = {							\
+		.sign = 's',						\
+		.realbits = real,					\
+		.storagebits = storage,					\
+	},								\
+}
+
+static const struct iio_chan_spec ad4858_channels[] = {
+	AD4851_IIO_CHANNEL(0, 20, 32),
+	AD4851_IIO_CHANNEL(1, 20, 32),
+	AD4851_IIO_CHANNEL(2, 20, 32),
+	AD4851_IIO_CHANNEL(3, 20, 32),
+	AD4851_IIO_CHANNEL(4, 20, 32),
+	AD4851_IIO_CHANNEL(5, 20, 32),
+	AD4851_IIO_CHANNEL(6, 20, 32),
+	AD4851_IIO_CHANNEL(7, 20, 32),
+};
+
+static const struct iio_chan_spec ad4857_channels[] = {
+	AD4851_IIO_CHANNEL(0, 16, 16),
+	AD4851_IIO_CHANNEL(1, 16, 16),
+	AD4851_IIO_CHANNEL(2, 16, 16),
+	AD4851_IIO_CHANNEL(3, 16, 16),
+	AD4851_IIO_CHANNEL(4, 16, 16),
+	AD4851_IIO_CHANNEL(5, 16, 16),
+	AD4851_IIO_CHANNEL(6, 16, 16),
+	AD4851_IIO_CHANNEL(7, 16, 16),
+};
+
+static const struct ad4851_chip_info ad4851_info = {
+	.name = "ad4851",
+	.product_id = 0x67,
+	.offset_table = ad4857_offset_table,
+	.num_offset = ARRAY_SIZE(ad4857_offset_table),
+	.channels = ad4857_channels,
+	.num_channels = ARRAY_SIZE(ad4857_channels),
+	.throughput = 250 * KILO,
+	.resolution = 16,
+};
+
+static const struct ad4851_chip_info ad4852_info = {
+	.name = "ad4852",
+	.product_id = 0x66,
+	.offset_table = ad4858_offset_table,
+	.num_offset = ARRAY_SIZE(ad4858_offset_table),
+	.channels = ad4858_channels,
+	.num_channels = ARRAY_SIZE(ad4858_channels),
+	.throughput = 250 * KILO,
+	.resolution = 20,
+};
+
+static const struct ad4851_chip_info ad4853_info = {
+	.name = "ad4853",
+	.product_id = 0x65,
+	.offset_table = ad4857_offset_table,
+	.num_offset = ARRAY_SIZE(ad4857_offset_table),
+	.channels = ad4857_channels,
+	.num_channels = ARRAY_SIZE(ad4857_channels),
+	.throughput = 1 * MEGA,
+	.resolution = 16,
+};
+
+static const struct ad4851_chip_info ad4854_info = {
+	.name = "ad4854",
+	.product_id = 0x64,
+	.offset_table = ad4858_offset_table,
+	.num_offset = ARRAY_SIZE(ad4858_offset_table),
+	.channels = ad4858_channels,
+	.num_channels = ARRAY_SIZE(ad4858_channels),
+	.throughput = 1 * MEGA,
+	.resolution = 20,
+};
+
+static const struct ad4851_chip_info ad4855_info = {
+	.name = "ad4855",
+	.product_id = 0x63,
+	.offset_table = ad4857_offset_table,
+	.num_offset = ARRAY_SIZE(ad4857_offset_table),
+	.channels = ad4857_channels,
+	.num_channels = ARRAY_SIZE(ad4857_channels),
+	.throughput = 250 * KILO,
+	.resolution = 16,
+};
+
+static const struct ad4851_chip_info ad4856_info = {
+	.name = "ad4856",
+	.product_id = 0x62,
+	.offset_table = ad4858_offset_table,
+	.num_offset = ARRAY_SIZE(ad4858_offset_table),
+	.channels = ad4858_channels,
+	.num_channels = ARRAY_SIZE(ad4858_channels),
+	.throughput = 250 * KILO,
+	.resolution = 20,
+};
+
+static const struct ad4851_chip_info ad4857_info = {
+	.name = "ad4857",
+	.product_id = 0x61,
+	.offset_table = ad4857_offset_table,
+	.num_offset = ARRAY_SIZE(ad4857_offset_table),
+	.channels = ad4857_channels,
+	.num_channels = ARRAY_SIZE(ad4857_channels),
+	.throughput = 1 * MEGA,
+	.resolution = 16,
+};
+
+static const struct ad4851_chip_info ad4858_info = {
+	.name = "ad4858",
+	.product_id = 0x60,
+	.offset_table = ad4858_offset_table,
+	.num_offset = ARRAY_SIZE(ad4858_offset_table),
+	.channels = ad4858_channels,
+	.num_channels = ARRAY_SIZE(ad4858_channels),
+	.throughput = 1 * MEGA,
+	.resolution = 20,
+};
+
+static const struct ad4851_chip_info ad4858i_info = {
+	.name = "ad4858i",
+	.product_id = 0x6F,
+	.offset_table = ad4858_offset_table,
+	.num_offset = ARRAY_SIZE(ad4858_offset_table),
+	.channels = ad4858_channels,
+	.num_channels = ARRAY_SIZE(ad4858_channels),
+	.throughput = 1 * MEGA,
+	.resolution = 20,
+};
+
+static const struct iio_info ad4851_iio_info = {
+	.debugfs_reg_access = ad4851_reg_access,
+	.read_raw = ad4851_read_raw,
+	.write_raw = ad4851_write_raw,
+	.update_scan_mode = ad4851_update_scan_mode,
+	.read_avail = ad4851_read_avail,
+};
+
+static const struct regmap_config regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.read_flag_mask = BIT(7),
+};
+
+static const char * const ad4851_power_supplies[] = {
+	"vcc",	"vdd", "vee", "vio",
+};
+
+static int ad4851_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct ad4851_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+
+	ret = devm_mutex_init(&spi->dev, &st->lock);
+	if (ret)
+		return ret;
+
+	ret = devm_regulator_bulk_get_enable(&spi->dev,
+					     ARRAY_SIZE(ad4851_power_supplies),
+					     ad4851_power_supplies);
+	if (ret)
+		return dev_err_probe(&spi->dev, ret,
+				     "failed to get and enable supplies\n");
+
+	ret = devm_regulator_get_enable_optional(&spi->dev, "vddh");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(&spi->dev, ret, "failed to get vddh voltage\n");
+
+	ret = devm_regulator_get_enable_optional(&spi->dev, "vddl");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(&spi->dev, ret, "failed to get vddl voltage\n");
+
+	st->vrefbuf = devm_regulator_get_optional(&spi->dev, "vrefbuf");
+	if (IS_ERR(st->vrefbuf)) {
+		if (PTR_ERR(st->vrefbuf) != -ENODEV)
+			return dev_err_probe(&spi->dev, PTR_ERR(st->vrefbuf),
+					     "Failed to get vrefbuf regulator\n");
+	}
+
+	st->vrefio = devm_regulator_get_optional(&spi->dev, "vrefio");
+	if (IS_ERR(st->vrefio)) {
+		if (PTR_ERR(st->vrefio) != -ENODEV)
+			return dev_err_probe(&spi->dev, PTR_ERR(st->vrefio),
+					     "Failed to get vrefbuf regulator\n");
+	}
+
+	st->pd_gpio = devm_gpiod_get_optional(&spi->dev, "pd", GPIOD_OUT_LOW);
+	if (IS_ERR(st->pd_gpio))
+		return dev_err_probe(&spi->dev, PTR_ERR(st->pd_gpio),
+				     "Error on requesting pd GPIO\n");
+
+	st->cnv = devm_pwm_get(&spi->dev, NULL);
+	if (IS_ERR(st->cnv))
+		return dev_err_probe(&spi->dev, PTR_ERR(st->cnv),
+				     "Error on requesting pwm\n");
+
+	st->info = spi_get_device_match_data(spi);
+	if (!st->info)
+		return -ENODEV;
+
+	st->regmap = devm_regmap_init_spi(spi, &regmap_config);
+	if (IS_ERR(st->regmap))
+		return PTR_ERR(st->regmap);
+
+	ret = ad4851_scale_offset_fill(st);
+	if (ret)
+		return ret;
+
+	ret = ad4851_setup(st);
+	if (ret)
+		return ret;
+
+	indio_dev->name = st->info->name;
+	indio_dev->channels = st->info->channels;
+	indio_dev->num_channels = st->info->num_channels;
+	indio_dev->info = &ad4851_iio_info;
+
+	st->back = devm_iio_backend_get(&spi->dev, NULL);
+	if (IS_ERR(st->back))
+		return PTR_ERR(st->back);
+
+	ret = devm_iio_backend_request_buffer(&spi->dev, st->back, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_backend_enable(&spi->dev, st->back);
+	if (ret)
+		return ret;
+
+	ret = ad4851_calibrate(st);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct of_device_id ad4851_of_match[] = {
+	{ .compatible = "adi,ad4851", .data = &ad4851_info, },
+	{ .compatible = "adi,ad4852", .data = &ad4852_info, },
+	{ .compatible = "adi,ad4853", .data = &ad4853_info, },
+	{ .compatible = "adi,ad4854", .data = &ad4854_info, },
+	{ .compatible = "adi,ad4855", .data = &ad4855_info, },
+	{ .compatible = "adi,ad4856", .data = &ad4856_info, },
+	{ .compatible = "adi,ad4857", .data = &ad4857_info, },
+	{ .compatible = "adi,ad4858", .data = &ad4858_info, },
+	{ .compatible = "adi,ad4858i", .data = &ad4858i_info, },
+	{ }
+};
+
+static const struct spi_device_id ad4851_spi_id[] = {
+	{ "ad4851", (kernel_ulong_t)&ad4851_info },
+	{ "ad4852", (kernel_ulong_t)&ad4852_info },
+	{ "ad4853", (kernel_ulong_t)&ad4853_info },
+	{ "ad4854", (kernel_ulong_t)&ad4854_info },
+	{ "ad4855", (kernel_ulong_t)&ad4855_info },
+	{ "ad4856", (kernel_ulong_t)&ad4856_info },
+	{ "ad4857", (kernel_ulong_t)&ad4857_info },
+	{ "ad4858", (kernel_ulong_t)&ad4858_info },
+	{ "ad4858i", (kernel_ulong_t)&ad4858i_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad4851_spi_id);
+
+static struct spi_driver ad4851_driver = {
+	.probe = ad4851_probe,
+	.driver = {
+		.name   = "ad4851",
+		.of_match_table = ad4851_of_match,
+	},
+	.id_table = ad4851_spi_id,
+};
+module_spi_driver(ad4851_driver);
+
+MODULE_AUTHOR("Sergiu Cuciurean <sergiu.cuciurean@...log.com>");
+MODULE_AUTHOR("Dragos Bogdan <dragos.bogdan@...log.com>");
+MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@...log.com>");
+MODULE_DESCRIPTION("Analog Devices AD4851 DAS driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(IIO_BACKEND);
-- 
2.46.2

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