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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 --- drivers/iio/amplifiers/hmc425a.c | 118 +++++++++++++++++++++++++++++-- 1 file changed, 114 insertions(+), 4 deletions(-) diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c index b116b54e4206..e7f425677fd3 100644 --- a/drivers/iio/amplifiers/hmc425a.c +++ b/drivers/iio/amplifiers/hmc425a.c @@ -2,9 +2,10 @@ /* * HMC425A and similar Gain Amplifiers * - * Copyright 2020 Analog Devices Inc. + * Copyright 2020, 2023 Analog Devices Inc. */ +#include #include #include #include @@ -20,10 +21,24 @@ #include #include +/* + * The LTC6373 amplifier supports configuring gain using GPIO's with the following + * values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16 + * + * Except for the shutdown value, all can be converted to dB using 20 * log10(x) + * From here, it is observed that all values are multiples of the '2' gain setting, + * with the correspondent of 6.020dB. + */ +#define LTC6373_CONVERSION_CONSTANT 6020 +#define LTC6373_MIN_GAIN_CODE 0x6 +#define LTC6373_CONVERSION_MASK GENMASK(2, 0) +#define LTC6373_SHUTDOWN GENMASK(2, 0) + enum hmc425a_type { ID_HMC425A, ID_HMC540S, - ID_ADRF5740 + ID_ADRF5740, + ID_LTC6373, }; struct hmc425a_chip_info { @@ -34,6 +49,8 @@ struct hmc425a_chip_info { int gain_min; int gain_max; int default_gain; + int powerdown_val; + bool has_powerdown; }; struct hmc425a_state { @@ -42,6 +59,7 @@ struct hmc425a_state { struct gpio_descs *gpios; enum hmc425a_type type; u32 gain; + bool powerdown; }; static int hmc425a_write(struct iio_dev *indio_dev, u32 value) @@ -80,6 +98,17 @@ static int hmc425a_gain_dB_to_code(struct hmc425a_state *st, int val, int val2, temp = (abs(gain) / 2000) & 0xF; *code = temp & BIT(3) ? temp | BIT(2) : temp; return 0; + case ID_LTC6373: + if (st->powerdown) + return -EPERM; + + /* add half of the value for rounding */ + temp = LTC6373_CONVERSION_CONSTANT / 2; + if (val < 0) + temp *= -1; + *code = ~((gain + temp) / LTC6373_CONVERSION_CONSTANT + 3) + & LTC6373_CONVERSION_MASK; + return 0; default: return -EINVAL; } @@ -101,6 +130,12 @@ static int hmc425a_code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2 code = code & BIT(3) ? code & ~BIT(2) : code; gain = code * -2000; break; + case ID_LTC6373: + if (st->powerdown) + return -EPERM; + gain = ((~code & LTC6373_CONVERSION_MASK) - 3) * + LTC6373_CONVERSION_CONSTANT; + break; } *val = gain / 1000; @@ -174,6 +209,48 @@ static const struct iio_info hmc425a_info = { .write_raw_get_fmt = &hmc425a_write_raw_get_fmt, }; +static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev, + uintptr_t private, + const struct iio_chan_spec *chan, + char *buf) +{ + struct hmc425a_state *st = iio_priv(indio_dev); + + return sysfs_emit(buf, "%d\n", st->powerdown); +} + +static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev, + uintptr_t private, + const struct iio_chan_spec *chan, + const char *buf, + size_t len) +{ + struct hmc425a_state *st = iio_priv(indio_dev); + bool powerdown; + int code, ret; + + ret = kstrtobool(buf, &powerdown); + if (ret) + return ret; + + mutex_lock(&st->lock); + st->powerdown = powerdown; + code = (powerdown) ? LTC6373_SHUTDOWN : st->gain; + ret = hmc425a_write(indio_dev, code); + mutex_unlock(&st->lock); + return len; +} + +static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = { + { + .name = "powerdown", + .read = ltc6373_read_powerdown, + .write = ltc6373_write_powerdown, + .shared = IIO_SEPARATE, + }, + {}, +}; + #define HMC425A_CHAN(_channel) \ { \ .type = IIO_VOLTAGE, \ @@ -183,10 +260,24 @@ static const struct iio_info hmc425a_info = { .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \ } +#define LTC6373_CHAN(_channel) \ +{ \ + .type = IIO_VOLTAGE, \ + .output = 1, \ + .indexed = 1, \ + .channel = _channel, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \ + .ext_info = ltc6373_ext_info, \ +} + static const struct iio_chan_spec hmc425a_channels[] = { HMC425A_CHAN(0), }; +static const struct iio_chan_spec ltc6373_channels[] = { + LTC6373_CHAN(0), +}; + static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = { [ID_HMC425A] = { .name = "hmc425a", @@ -215,6 +306,18 @@ static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = { .gain_max = 0, .default_gain = 0xF, /* set default gain -22.0db*/ }, + [ID_LTC6373] = { + .name = "ltc6373", + .channels = ltc6373_channels, + .num_channels = ARRAY_SIZE(ltc6373_channels), + .num_gpios = 3, + .gain_min = -12041, /* gain setting x0.25*/ + .gain_max = 24082, /* gain setting x16 */ + .default_gain = LTC6373_MIN_GAIN_CODE, + .powerdown_val = LTC6373_SHUTDOWN, + .has_powerdown = true, + }, + }; /* Match table for of_platform binding */ @@ -225,6 +328,8 @@ static const struct of_device_id hmc425a_of_match[] = { .data = &hmc425a_chip_info_tbl[ID_HMC540S]}, { .compatible = "adi,adrf5740", .data = &hmc425a_chip_info_tbl[ID_ADRF5740]}, + { .compatible = "adi,ltc6373", + .data = &hmc425a_chip_info_tbl[ID_LTC6373]}, {}, }; MODULE_DEVICE_TABLE(of, hmc425a_of_match); @@ -270,8 +375,13 @@ static int hmc425a_probe(struct platform_device *pdev) indio_dev->info = &hmc425a_info; indio_dev->modes = INDIO_DIRECT_MODE; - /* Set default gain */ - hmc425a_write(indio_dev, st->gain); + if (st->chip_info->has_powerdown) { + st->powerdown = true; + hmc425a_write(indio_dev, st->chip_info->powerdown_val); + } else { + /* Set default gain */ + hmc425a_write(indio_dev, st->gain); + } return devm_iio_device_register(&pdev->dev, indio_dev); }