Messages in this thread Patch in this message |  | | From | Marcelo Schmitt <> | | Subject | [PATCH v1 7/7] iio: adc: ad4170: Add support for weigh scale and RTD sensors | | Date | Wed, 9 Apr 2025 09:26:22 -0300 |
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The AD4170 design has features to aid interfacing with weigh scale and RTD sensors that are expected to be setup with external circuitry for proper sensor operation. A key characteristic of those sensors is that the circuit they are in must be excited with a pair of signals. The external circuit can be excited either by voltage supply or by AD4170 excitation signals. The sensor can then be read through a different pair of lines that are connected to AD4170 ADC.
Configure AD4170 to handle external circuit sensors.
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com> --- drivers/iio/adc/ad4170.c | 341 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 338 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/adc/ad4170.c b/drivers/iio/adc/ad4170.c index d204f8ca840f..2cf578608316 100644 --- a/drivers/iio/adc/ad4170.c +++ b/drivers/iio/adc/ad4170.c @@ -77,6 +77,7 @@ #define AD4170_OFFSET_REG(x) (0xCA + 14 * (x)) #define AD4170_GAIN_REG(x) (0xCD + 14 * (x)) #define AD4170_V_BIAS_REG 0x135 +#define AD4170_CURRENT_SRC_REG(x) (0x139 + 2 * (x)) #define AD4170_FIR_CTRL 0x141 #define AD4170_COEFF_DATA_REG 0x14A #define AD4170_COEFF_ADDR_REG 0x14C @@ -127,6 +128,10 @@ /* AD4170_FILTER_REG */ #define AD4170_FILTER_FILTER_TYPE_MSK GENMASK(3, 0) +/* AD4170_CURRENT_SRC_REG */ +#define AD4170_CURRENT_SRC_I_OUT_PIN_MSK GENMASK(12, 8) +#define AD4170_CURRENT_SRC_I_OUT_VAL_MSK GENMASK(2, 0) + /* AD4170 register constants */ /* AD4170_CLOCK_CTRL_REG constants */ @@ -188,6 +193,21 @@ #define AD4170_FILTER_FILTER_TYPE_SINC5 0x4 #define AD4170_FILTER_FILTER_TYPE_SINC3 0x6 +/* AD4170_CURRENT_SRC_REG constants */ +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN0 0 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN1 1 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN2 2 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN3 3 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN4 4 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN5 5 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN6 6 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN7 7 +#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN8 8 +#define AD4170_CURRENT_SRC_I_OUT_PIN_GPIO0 17 +#define AD4170_CURRENT_SRC_I_OUT_PIN_GPIO1 18 +#define AD4170_CURRENT_SRC_I_OUT_PIN_GPIO2 19 +#define AD4170_CURRENT_SRC_I_OUT_PIN_GPIO3 20 + /* Device properties and auxiliary constants */ #define AD4170_NUM_ANALOG_PINS 9 @@ -222,6 +242,12 @@ #define AD4170_PIN_UNASIGNED 0x00 #define AD4170_PIN_ANALOG_IN 0x01 #define AD4170_PIN_CURRENT_OUT 0x02 +#define AD4170_PIN_VBIAS 0x04 + +/* GPIO pin functions */ +#define AD4170_GPIO_UNASIGNED 0x00 +#define AD4170_GPIO_AC_EXCITATION 0x02 +#define AD4170_GPIO_OUTPUT 0x04 enum ad4170_ref_buf { AD4170_REF_BUF_PRE, /* Pre-charge referrence buffer */ @@ -278,6 +304,33 @@ static const unsigned int ad4170_sinc5_filt_fs_tbl[] = { 1, 2, 4, 8, 12, 16, 20, 40, 48, 80, 100, 256 }; +static const unsigned int ad4170_iout_pin_tbl[] = { + AD4170_CURRENT_SRC_I_OUT_PIN_AIN0, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN1, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN2, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN3, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN4, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN5, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN6, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN7, + AD4170_CURRENT_SRC_I_OUT_PIN_AIN8, + AD4170_CURRENT_SRC_I_OUT_PIN_GPIO0, + AD4170_CURRENT_SRC_I_OUT_PIN_GPIO1, + AD4170_CURRENT_SRC_I_OUT_PIN_GPIO2, + AD4170_CURRENT_SRC_I_OUT_PIN_GPIO3, +}; + +static const unsigned int ad4170_iout_current_ua_tbl[] = { + 0, 10, 50, 100, 250, 500, 1000, 1500 +}; + +enum ad4170_sensor_type { + AD4170_ADC_SENSOR = 0, + AD4170_WEIGH_SCALE_SENSOR = 1, + AD4170_THERMOCOUPLE_SENSOR = 2, + AD4170_RTD_SENSOR = 3, +}; + static const char * const ad4170_chip_names[] = { "ad4170", "ad4190", @@ -343,6 +396,7 @@ struct ad4170_state { struct clk *ext_clk; struct clk_hw int_clk_hw; int pins_fn[AD4170_NUM_ANALOG_PINS]; + int gpio_fn[AD4170_NUM_GPIO_PINS]; struct gpio_chip gpiochip; u32 int_pin_sel; int sps_tbl[ARRAY_SIZE(ad4170_filt_names)][AD4170_MAX_FS_TBL_SIZE][2]; @@ -956,6 +1010,19 @@ static int ad4170_get_ain_voltage_uv(struct ad4170_state *st, int ain_n, struct device *dev = &st->spi->dev; *ain_voltage = 0; + /* + * The voltage bias (vbias) sets the common-mode voltage of the channel + * to (AVDD + AVSS)/2. If provided, AVSS supply provides the magnitude + * (absolute value) of the negative voltage supplied to the AVSS pin. + * So, we do AVDD - AVSS to compute the DC voltage generated by the bias + * voltage generator. + */ + if (st->pins_fn[ain_n] & AD4170_PIN_VBIAS) { + *ain_voltage = (st->vrefs_uv[AD4170_AVDD_SUP] + - st->vrefs_uv[AD4170_AVSS_SUP]) / 2; + return 0; + } + if (ain_n <= AD4170_CHAN_MAP_TEMP_SENSOR) return 0; @@ -1746,6 +1813,242 @@ static int ad4170_gpio_init(struct iio_dev *indio_dev) return devm_gpiochip_add_data(&st->spi->dev, &st->gpiochip, indio_dev); } +static int _ad4170_find_table_index(const unsigned int *tbl, size_t len, + unsigned int val) +{ + unsigned int i; + + for (i = 0; i < len; i++) + if (tbl[i] == val) + return i; + + return -EINVAL; +} + +#define ad4170_find_table_index(table, val) \ + _ad4170_find_table_index(table, ARRAY_SIZE(table), val) + +static int ad4170_validate_excitation_pins(struct ad4170_state *st, + u32 *exc_pins, int num_exc_pins) +{ + struct device *dev = &st->spi->dev; + int ret, i; + + for (i = 0; i < num_exc_pins; i++) { + unsigned int pin = exc_pins[i]; + + ret = ad4170_find_table_index(ad4170_iout_pin_tbl, pin); + if (ret < 0) + return dev_err_probe(dev, ret, + "Invalid excitation pin: %u\n", + pin); + + if (pin <= AD4170_MAX_ANALOG_PINS) { + if (st->pins_fn[pin] != AD4170_PIN_UNASIGNED) + return dev_err_probe(dev, -EINVAL, + "Pin %u already used with fn %u\n", + pin, st->pins_fn[pin]); + + st->pins_fn[pin] = AD4170_PIN_CURRENT_OUT; + } else { + unsigned int gpio = pin - AD4170_CURRENT_SRC_I_OUT_PIN_GPIO0; + + if (st->gpio_fn[gpio] != AD4170_GPIO_UNASIGNED) + return dev_err_probe(dev, -EINVAL, + "GPIO %u already used with fn %u\n", + gpio, st->gpio_fn[gpio]); + + st->gpio_fn[gpio] = AD4170_GPIO_AC_EXCITATION; + } + } + return 0; +} + +static int ad4170_setup_rtd(struct ad4170_state *st, + struct fwnode_handle *child, + struct ad4170_setup *setup, u32 *exc_pins, + int num_exc_pins, int exc_cur, bool ac_excited) +{ + int current_src, ret, i; + + for (i = 0; i < num_exc_pins; i++) { + unsigned int pin = exc_pins[i]; + + current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_PIN_MSK, pin); + current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_VAL_MSK, exc_cur); + + ret = regmap_write(st->regmap16, AD4170_CURRENT_SRC_REG(i), + current_src); + if (ret) + return ret; + } + + if (ac_excited) + setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_IEXC_MSK, + num_exc_pins == 2 ? 0x2 : 0x3); + + return 0; +} + +static int ad4170_setup_bridge(struct ad4170_state *st, + struct fwnode_handle *child, + struct ad4170_setup *setup, u32 *exc_pins, + int num_exc_pins, int exc_cur, bool ac_excited) +{ + int current_src, ret, i; + + if (!ac_excited) + return 0; + + /* + * If a specific current is provided through + * adi,excitation-current-microamp, set excitation pins provided through + * adi,excitation-pins to AC excite the bridge circuit. Else, use + * predefined ACX1, ACX1 negated, ACX2, ACX2 negated signals to AC + * excite the bridge. Those signals are output on GPIO2, GPIO0, GPIO3, + * and GPIO1, respectively. If only two pins are specified for AC + * excitation, use ACX1 and ACX2. See AD4170 datasheet for instructions + * on how to setup the bridge circuit. + * + * Also, to avoid any short-circuit condition when more than one channel + * is enabled, set GPIO2 and GPIO0 high, and set GPIO1 and GPIO3 low to + * DC excite the bridge whenever a channel without AC excitation is + * selected. That is needed because GPIO pins are controlled by the next + * highest priority GPIO function when a channel doesn't enable AC + * excitation. See datasheet Figure 113 Weigh Scale (AC Excitation) for + * an example circuit diagram. + */ + if (exc_cur == 0) { + if (num_exc_pins == 2) { + setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_ADC_MSK, 0x3); + ret = regmap_set_bits(st->regmap16, + AD4170_GPIO_MODE_REG, + BIT(7) | BIT(5)); + if (ret) + return ret; + + ret = regmap_set_bits(st->regmap16, + AD4170_GPIO_OUTPUT_REG, + BIT(3) | BIT(2)); + if (ret) + return ret; + + st->gpio_fn[3] |= AD4170_GPIO_OUTPUT; + st->gpio_fn[2] |= AD4170_GPIO_OUTPUT; + } else { + setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_ADC_MSK, 0x2); + ret = regmap_set_bits(st->regmap16, + AD4170_GPIO_MODE_REG, + BIT(7) | BIT(5) | BIT(3) | BIT(1)); + if (ret) + return ret; + + ret = regmap_set_bits(st->regmap16, + AD4170_GPIO_OUTPUT_REG, + BIT(3) | BIT(2) | BIT(1) | BIT(0)); + if (ret) + return ret; + + st->gpio_fn[3] |= AD4170_GPIO_OUTPUT; + st->gpio_fn[2] |= AD4170_GPIO_OUTPUT; + st->gpio_fn[1] |= AD4170_GPIO_OUTPUT; + st->gpio_fn[0] |= AD4170_GPIO_OUTPUT; + } + + return 0; + } + for (i = 0; i < num_exc_pins; i++) { + unsigned int pin = exc_pins[i]; + + current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_PIN_MSK, pin); + current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_VAL_MSK, exc_cur); + + ret = regmap_write(st->regmap16, AD4170_CURRENT_SRC_REG(i), + current_src); + if (ret) + return ret; + } + + setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_IEXC_MSK, + num_exc_pins == 2 ? 0x2 : 0x3); + + return 0; +} + +static int ad4170_parse_external_sensor(struct ad4170_state *st, + struct fwnode_handle *child, + struct ad4170_setup *setup, + struct iio_chan_spec *chan, u8 s_type) +{ + unsigned int num_exc_pins, exc_cur, reg_val; + struct device *dev = &st->spi->dev; + u32 pins[2], exc_pins[4]; + bool ac_excited, vbias; + int ret; + + ret = fwnode_property_read_u32_array(child, "diff-channels", pins, + ARRAY_SIZE(pins)); + if (ret) + return dev_err_probe(dev, ret, + "Failed to read sensor diff-channels\n"); + + chan->differential = true; + chan->channel = pins[0]; + chan->channel2 = pins[1]; + + ac_excited = fwnode_property_read_bool(child, "adi,ac-excited"); + + num_exc_pins = fwnode_property_count_u32(child, "adi,excitation-pins"); + if (num_exc_pins != 2 && num_exc_pins != 4) + return dev_err_probe(dev, -EINVAL, + "Invalid number of excitation pins\n"); + + ret = fwnode_property_read_u32_array(child, "adi,excitation-pins", + exc_pins, num_exc_pins); + if (ret) + return dev_err_probe(dev, ret, + "Failed to read adi,excitation-pins\n"); + + ret = ad4170_validate_excitation_pins(st, exc_pins, num_exc_pins); + if (ret) + return ret; + + exc_cur = 0; + ret = fwnode_property_read_u32(child, "adi,excitation-current-microamp", + &exc_cur); + if (ret && s_type == AD4170_RTD_SENSOR) + return dev_err_probe(dev, ret, + "Failed to read adi,excitation-current-microamp\n"); + + ret = ad4170_find_table_index(ad4170_iout_current_ua_tbl, exc_cur); + if (ret < 0) + return dev_err_probe(dev, ret, + "Invalid excitation current: %uuA\n", + exc_cur); + + /* Get the excitation current configuration value */ + exc_cur = ret; + + if (s_type == AD4170_THERMOCOUPLE_SENSOR) { + vbias = fwnode_property_read_bool(child, "adi,vbias"); + if (vbias) { + st->pins_fn[chan->channel2] |= AD4170_PIN_VBIAS; + reg_val = BIT(chan->channel2); + return regmap_write(st->regmap16, AD4170_V_BIAS_REG, + reg_val); + } + } + if (s_type == AD4170_WEIGH_SCALE_SENSOR || + s_type == AD4170_THERMOCOUPLE_SENSOR) { + ret = ad4170_setup_bridge(st, child, setup, exc_pins, + num_exc_pins, exc_cur, ac_excited); + } else { + ret = ad4170_setup_rtd(st, child, setup, exc_pins, num_exc_pins, + exc_cur, ac_excited); + } + return ret; +} + static int ad4170_parse_reference(struct ad4170_state *st, struct fwnode_handle *child, struct ad4170_setup *setup) @@ -1827,6 +2130,7 @@ static int ad4170_parse_channel_node(struct iio_dev *indio_dev, struct ad4170_state *st = iio_priv(indio_dev); struct device *dev = &st->spi->dev; struct ad4170_chan_info *chan_info; + u8 s_type = AD4170_ADC_SENSOR; struct ad4170_setup *setup; struct iio_chan_spec *chan; unsigned int ch_reg; @@ -1857,10 +2161,34 @@ static int ad4170_parse_channel_node(struct iio_dev *indio_dev, if (ret) return ret; - ret = ad4170_parse_adc_channel_type(dev, child, chan); - if (ret < 0) - return ret; + ret = fwnode_property_read_u8(child, "adi,sensor-type", &s_type); + if (!ret) { + if (s_type > AD4170_RTD_SENSOR) + return dev_err_probe(dev, ret, + "Invalid adi,sensor-type: %u\n", + s_type); + } + switch (s_type) { + case AD4170_ADC_SENSOR: + ret = ad4170_parse_adc_channel_type(dev, child, chan); + if (ret < 0) + return ret; + break; + case AD4170_WEIGH_SCALE_SENSOR: + fallthrough; + case AD4170_THERMOCOUPLE_SENSOR: + fallthrough; + case AD4170_RTD_SENSOR: + ret = ad4170_parse_external_sensor(st, child, setup, chan, + s_type); + if (ret < 0) + return ret; + + break; + default: + return -EINVAL; + } bipolar = fwnode_property_read_bool(child, "bipolar"); setup->afe |= FIELD_PREP(AD4170_AFE_BIPOLAR_MSK, bipolar); if (bipolar) @@ -2057,6 +2385,9 @@ static int ad4170_parse_firmware(struct iio_dev *indio_dev) for (i = 0; i < AD4170_NUM_ANALOG_PINS; i++) st->pins_fn[i] = AD4170_PIN_UNASIGNED; + for (i = 0; i < AD4170_NUM_GPIO_PINS; i++) + st->gpio_fn[i] = AD4170_GPIO_UNASIGNED; + /* On power on, device defaults to using SDO pin for data ready signal */ st->int_pin_sel = AD4170_INT_PIN_SDO; ret = device_property_match_property_string(dev, "interrupt-names", @@ -2081,6 +2412,10 @@ static int ad4170_parse_firmware(struct iio_dev *indio_dev) /* Only create a GPIO chip if flagged for it */ if (device_property_read_bool(&st->spi->dev, "gpio-controller")) { + for (i = 0; i < AD4170_NUM_GPIO_PINS; i++) + if (st->gpio_fn[i] != AD4170_GPIO_UNASIGNED) + return 0; + ret = ad4170_gpio_init(indio_dev); if (ret < 0) return ret; -- 2.47.2
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