a0e7a2b703
This adds support for LTC6373 36 V Fully-Differential Programmable-Gain Instrumentation Amplifier with 25 pA Input Bias Current. The user can program the gain to one of seven available settings through a 3-bit parallel interface (A2 to A0). Signed-off-by: Dumitru Ceclan <mitrutzceclan@gmail.com> Reviewed-by: Nuno Sa <nuno.sa@analog.com> Link: https://lore.kernel.org/r/20240220153553.2432-6-mitrutzceclan@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
428 lines
10 KiB
C
428 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* HMC425A and similar Gain Amplifiers
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*
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* Copyright 2020, 2024 Analog Devices Inc.
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*/
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#include <linux/bits.h>
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#include <linux/bitops.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/kernel.h>
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#include <linux/math.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/slab.h>
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#include <linux/regulator/consumer.h>
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#include <linux/sysfs.h>
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/*
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* The LTC6373 amplifier supports configuring gain using GPIO's with the following
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* values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16
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*
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* Except for the shutdown value, all can be converted to dB using 20 * log10(x)
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* From here, it is observed that all values are multiples of the '2' gain setting,
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* with the correspondent of 6.020dB.
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*/
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#define LTC6373_CONVERSION_CONSTANT 6020
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#define LTC6373_MIN_GAIN_CODE 0x6
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#define LTC6373_CONVERSION_MASK GENMASK(2, 0)
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#define LTC6373_SHUTDOWN GENMASK(2, 0)
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enum hmc425a_type {
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ID_HMC425A,
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ID_HMC540S,
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ID_ADRF5740,
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ID_LTC6373,
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};
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struct hmc425a_chip_info {
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const char *name;
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const struct iio_chan_spec *channels;
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unsigned int num_channels;
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unsigned int num_gpios;
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int gain_min;
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int gain_max;
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int default_gain;
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int powerdown_val;
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bool has_powerdown;
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int (*gain_dB_to_code)(int gain, int *code);
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int (*code_to_gain_dB)(int code, int *val, int *val2);
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};
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struct hmc425a_state {
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struct mutex lock; /* protect sensor state */
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const struct hmc425a_chip_info *chip_info;
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struct gpio_descs *gpios;
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u32 gain;
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bool powerdown;
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};
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static int gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code)
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{
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const struct hmc425a_chip_info *inf = st->chip_info;
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int gain;
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if (val < 0)
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gain = (val * 1000) - (val2 / 1000);
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else
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gain = (val * 1000) + (val2 / 1000);
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if (gain > inf->gain_max || gain < inf->gain_min)
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return -EINVAL;
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if (st->powerdown)
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return -EPERM;
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return st->chip_info->gain_dB_to_code(gain, code);
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}
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static int hmc425a_gain_dB_to_code(int gain, int *code)
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{
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*code = ~((abs(gain) / 500) & 0x3F);
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return 0;
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}
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static int hmc540s_gain_dB_to_code(int gain, int *code)
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{
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*code = ~((abs(gain) / 1000) & 0xF);
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return 0;
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}
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static int adrf5740_gain_dB_to_code(int gain, int *code)
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{
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int temp = (abs(gain) / 2000) & 0xF;
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/* Bit [0-3]: 2dB 4dB 8dB 8dB */
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*code = temp & BIT(3) ? temp | BIT(2) : temp;
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return 0;
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}
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static int ltc6373_gain_dB_to_code(int gain, int *code)
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{
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*code = ~(DIV_ROUND_CLOSEST(gain, LTC6373_CONVERSION_CONSTANT) + 3)
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& LTC6373_CONVERSION_MASK;
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return 0;
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}
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static int code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2)
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{
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if (st->powerdown)
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return -EPERM;
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return st->chip_info->code_to_gain_dB(st->gain, val, val2);
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}
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static int hmc425a_code_to_gain_dB(int code, int *val, int *val2)
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{
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*val = (~code * -500) / 1000;
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*val2 = ((~code * -500) % 1000) * 1000;
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return 0;
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}
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static int hmc540s_code_to_gain_dB(int code, int *val, int *val2)
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{
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*val = (~code * -1000) / 1000;
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*val2 = ((~code * -1000) % 1000) * 1000;
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return 0;
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}
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static int adrf5740_code_to_gain_dB(int code, int *val, int *val2)
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{
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/*
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* Bit [0-3]: 2dB 4dB 8dB 8dB
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* When BIT(3) is set, unset BIT(2) and use 3 as double the place value
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*/
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code = code & BIT(3) ? code & ~BIT(2) : code;
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*val = (code * -2000) / 1000;
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*val2 = ((code * -2000) % 1000) * 1000;
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return 0;
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}
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static int ltc6373_code_to_gain_dB(int code, int *val, int *val2)
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{
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int gain = ((~code & LTC6373_CONVERSION_MASK) - 3) *
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LTC6373_CONVERSION_CONSTANT;
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*val = gain / 1000;
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*val2 = (gain % 1000) * 1000;
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return 0;
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}
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static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
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{
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struct hmc425a_state *st = iio_priv(indio_dev);
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DECLARE_BITMAP(values, BITS_PER_TYPE(value));
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values[0] = value;
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gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
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NULL, values);
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return 0;
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}
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static int hmc425a_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long m)
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{
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struct hmc425a_state *st = iio_priv(indio_dev);
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int ret;
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mutex_lock(&st->lock);
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switch (m) {
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case IIO_CHAN_INFO_HARDWAREGAIN:
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ret = code_to_gain_dB(st, val, val2);
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if (ret)
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break;
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ret = IIO_VAL_INT_PLUS_MICRO_DB;
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break;
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default:
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ret = -EINVAL;
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}
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mutex_unlock(&st->lock);
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return ret;
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};
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static int hmc425a_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int val,
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int val2, long mask)
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{
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struct hmc425a_state *st = iio_priv(indio_dev);
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int code = 0, ret;
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mutex_lock(&st->lock);
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switch (mask) {
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case IIO_CHAN_INFO_HARDWAREGAIN:
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ret = gain_dB_to_code(st, val, val2, &code);
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if (ret)
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break;
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st->gain = code;
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ret = hmc425a_write(indio_dev, st->gain);
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break;
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default:
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ret = -EINVAL;
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}
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mutex_unlock(&st->lock);
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return ret;
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}
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static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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long mask)
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{
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switch (mask) {
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case IIO_CHAN_INFO_HARDWAREGAIN:
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return IIO_VAL_INT_PLUS_MICRO_DB;
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default:
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return -EINVAL;
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}
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}
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static const struct iio_info hmc425a_info = {
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.read_raw = &hmc425a_read_raw,
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.write_raw = &hmc425a_write_raw,
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.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
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};
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static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev,
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uintptr_t private,
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const struct iio_chan_spec *chan,
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char *buf)
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{
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struct hmc425a_state *st = iio_priv(indio_dev);
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return sysfs_emit(buf, "%d\n", st->powerdown);
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}
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static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev,
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uintptr_t private,
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const struct iio_chan_spec *chan,
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const char *buf,
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size_t len)
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{
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struct hmc425a_state *st = iio_priv(indio_dev);
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bool powerdown;
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int code, ret;
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ret = kstrtobool(buf, &powerdown);
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if (ret)
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return ret;
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mutex_lock(&st->lock);
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st->powerdown = powerdown;
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code = (powerdown) ? LTC6373_SHUTDOWN : st->gain;
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hmc425a_write(indio_dev, code);
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mutex_unlock(&st->lock);
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return len;
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}
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static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = {
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{
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.name = "powerdown",
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.read = ltc6373_read_powerdown,
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.write = ltc6373_write_powerdown,
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.shared = IIO_SEPARATE,
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},
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{}
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};
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#define HMC425A_CHAN(_channel) \
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{ \
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.type = IIO_VOLTAGE, \
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.output = 1, \
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.indexed = 1, \
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.channel = _channel, \
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.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
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}
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#define LTC6373_CHAN(_channel) \
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{ \
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.type = IIO_VOLTAGE, \
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.output = 1, \
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.indexed = 1, \
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.channel = _channel, \
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.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
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.ext_info = ltc6373_ext_info, \
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}
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static const struct iio_chan_spec hmc425a_channels[] = {
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HMC425A_CHAN(0),
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};
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static const struct iio_chan_spec ltc6373_channels[] = {
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LTC6373_CHAN(0),
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};
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static const struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
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[ID_HMC425A] = {
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.name = "hmc425a",
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.channels = hmc425a_channels,
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.num_channels = ARRAY_SIZE(hmc425a_channels),
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.num_gpios = 6,
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.gain_min = -31500,
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.gain_max = 0,
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.default_gain = -0x40, /* set default gain -31.5db*/
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.gain_dB_to_code = hmc425a_gain_dB_to_code,
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.code_to_gain_dB = hmc425a_code_to_gain_dB,
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},
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[ID_HMC540S] = {
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.name = "hmc540s",
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.channels = hmc425a_channels,
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.num_channels = ARRAY_SIZE(hmc425a_channels),
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.num_gpios = 4,
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.gain_min = -15000,
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.gain_max = 0,
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.default_gain = -0x10, /* set default gain -15.0db*/
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.gain_dB_to_code = hmc540s_gain_dB_to_code,
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.code_to_gain_dB = hmc540s_code_to_gain_dB,
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},
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[ID_ADRF5740] = {
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.name = "adrf5740",
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.channels = hmc425a_channels,
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.num_channels = ARRAY_SIZE(hmc425a_channels),
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.num_gpios = 4,
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.gain_min = -22000,
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.gain_max = 0,
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.default_gain = 0xF, /* set default gain -22.0db*/
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.gain_dB_to_code = adrf5740_gain_dB_to_code,
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.code_to_gain_dB = adrf5740_code_to_gain_dB,
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},
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[ID_LTC6373] = {
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.name = "ltc6373",
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.channels = ltc6373_channels,
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.num_channels = ARRAY_SIZE(ltc6373_channels),
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.num_gpios = 3,
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.gain_min = -12041, /* gain setting x0.25*/
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.gain_max = 24082, /* gain setting x16 */
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.default_gain = LTC6373_MIN_GAIN_CODE,
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.powerdown_val = LTC6373_SHUTDOWN,
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.has_powerdown = true,
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.gain_dB_to_code = ltc6373_gain_dB_to_code,
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.code_to_gain_dB = ltc6373_code_to_gain_dB,
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},
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};
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static int hmc425a_probe(struct platform_device *pdev)
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{
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struct iio_dev *indio_dev;
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struct hmc425a_state *st;
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int ret;
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indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
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if (!indio_dev)
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return -ENOMEM;
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st = iio_priv(indio_dev);
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st->chip_info = device_get_match_data(&pdev->dev);
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indio_dev->num_channels = st->chip_info->num_channels;
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indio_dev->channels = st->chip_info->channels;
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indio_dev->name = st->chip_info->name;
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st->gain = st->chip_info->default_gain;
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st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
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if (IS_ERR(st->gpios))
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return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
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"failed to get gpios\n");
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if (st->gpios->ndescs != st->chip_info->num_gpios) {
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dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
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st->chip_info->num_gpios);
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return -ENODEV;
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}
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ret = devm_regulator_get_enable(&pdev->dev, "vcc-supply");
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if (ret)
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return ret;
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mutex_init(&st->lock);
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indio_dev->info = &hmc425a_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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if (st->chip_info->has_powerdown) {
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st->powerdown = true;
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hmc425a_write(indio_dev, st->chip_info->powerdown_val);
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} else {
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/* Set default gain */
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hmc425a_write(indio_dev, st->gain);
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}
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return devm_iio_device_register(&pdev->dev, indio_dev);
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}
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/* Match table for of_platform binding */
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static const struct of_device_id hmc425a_of_match[] = {
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{ .compatible = "adi,hmc425a",
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.data = &hmc425a_chip_info_tbl[ID_HMC425A]},
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{ .compatible = "adi,hmc540s",
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.data = &hmc425a_chip_info_tbl[ID_HMC540S]},
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{ .compatible = "adi,adrf5740",
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.data = &hmc425a_chip_info_tbl[ID_ADRF5740]},
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{ .compatible = "adi,ltc6373",
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.data = &hmc425a_chip_info_tbl[ID_LTC6373]},
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{}
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};
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MODULE_DEVICE_TABLE(of, hmc425a_of_match);
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static struct platform_driver hmc425a_driver = {
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.driver = {
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.name = KBUILD_MODNAME,
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.of_match_table = hmc425a_of_match,
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},
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.probe = hmc425a_probe,
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};
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module_platform_driver(hmc425a_driver);
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MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
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MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
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MODULE_LICENSE("GPL v2");
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