// SPDX-License-Identifier: GPL-2.0 /* * Texas Instruments LMP92064 SPI ADC driver * * Copyright (c) 2022 Leonard Göhrs <kernel@pengutronix.de>, Pengutronix * * Based on linux/drivers/iio/adc/ti-tsc2046.c * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix */ #include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/module.h> #include <linux/regmap.h> #include <linux/regulator/consumer.h> #include <linux/spi/spi.h> #include <linux/iio/iio.h> #include <linux/iio/driver.h> #define TI_LMP92064_REG_CONFIG_A 0x0000 #define TI_LMP92064_REG_CONFIG_B 0x0001 #define TI_LMP92064_REG_CHIP_REV 0x0006 #define TI_LMP92064_REG_MFR_ID1 0x000C #define TI_LMP92064_REG_MFR_ID2 0x000D #define TI_LMP92064_REG_REG_UPDATE 0x000F #define TI_LMP92064_REG_CONFIG_REG 0x0100 #define TI_LMP92064_REG_STATUS 0x0103 #define TI_LMP92064_REG_DATA_VOUT_LSB 0x0200 #define TI_LMP92064_REG_DATA_VOUT_MSB 0x0201 #define TI_LMP92064_REG_DATA_COUT_LSB 0x0202 #define TI_LMP92064_REG_DATA_COUT_MSB 0x0203 #define TI_LMP92064_VAL_CONFIG_A 0x99 #define TI_LMP92064_VAL_CONFIG_B 0x00 #define TI_LMP92064_VAL_STATUS_OK 0x01 /* * Channel number definitions for the two channels of the device * - IN Current (INC) * - IN Voltage (INV) */ #define TI_LMP92064_CHAN_INC 0 #define TI_LMP92064_CHAN_INV 1 static const struct regmap_range lmp92064_readable_reg_ranges[] = { regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CHIP_REV), regmap_reg_range(TI_LMP92064_REG_MFR_ID1, TI_LMP92064_REG_MFR_ID2), regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE), regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG), regmap_reg_range(TI_LMP92064_REG_STATUS, TI_LMP92064_REG_STATUS), regmap_reg_range(TI_LMP92064_REG_DATA_VOUT_LSB, TI_LMP92064_REG_DATA_COUT_MSB), }; static const struct regmap_access_table lmp92064_readable_regs = { .yes_ranges = lmp92064_readable_reg_ranges, .n_yes_ranges = ARRAY_SIZE(lmp92064_readable_reg_ranges), }; static const struct regmap_range lmp92064_writable_reg_ranges[] = { regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CONFIG_B), regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE), regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG), }; static const struct regmap_access_table lmp92064_writable_regs = { .yes_ranges = lmp92064_writable_reg_ranges, .n_yes_ranges = ARRAY_SIZE(lmp92064_writable_reg_ranges), }; static const struct regmap_config lmp92064_spi_regmap_config = { .reg_bits = 16, .val_bits = 8, .max_register = TI_LMP92064_REG_DATA_COUT_MSB, .rd_table = &lmp92064_readable_regs, .wr_table = &lmp92064_writable_regs, }; struct lmp92064_adc_priv { int shunt_resistor_uohm; struct spi_device *spi; struct regmap *regmap; }; static const struct iio_chan_spec lmp92064_adc_channels[] = { { .type = IIO_CURRENT, .address = TI_LMP92064_CHAN_INC, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .datasheet_name = "INC", }, { .type = IIO_VOLTAGE, .address = TI_LMP92064_CHAN_INV, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .datasheet_name = "INV", }, }; static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res) { __be16 raw[2]; int ret; /* * The ADC only latches in new samples if all DATA registers are read * in descending sequential order. * The ADC auto-decrements the register index with each clocked byte. * Read both channels in single SPI transfer by selecting the highest * register using the command below and clocking out all four data * bytes. */ ret = regmap_bulk_read(priv->regmap, TI_LMP92064_REG_DATA_COUT_MSB, &raw, sizeof(raw)); if (ret) { dev_err(&priv->spi->dev, "regmap_bulk_read failed: %pe\n", ERR_PTR(ret)); return ret; } res[0] = be16_to_cpu(raw[0]); res[1] = be16_to_cpu(raw[1]); return 0; } static int lmp92064_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) { struct lmp92064_adc_priv *priv = iio_priv(indio_dev); u16 raw[2]; int ret; switch (mask) { case IIO_CHAN_INFO_RAW: ret = lmp92064_read_meas(priv, raw); if (ret < 0) return ret; *val = (chan->address == TI_LMP92064_CHAN_INC) ? raw[0] : raw[1]; return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: if (chan->address == TI_LMP92064_CHAN_INC) { /* * processed (mA) = raw * current_lsb (mA) * current_lsb (mA) = shunt_voltage_lsb (nV) / shunt_resistor (uOhm) * shunt_voltage_lsb (nV) = 81920000 / 4096 = 20000 */ *val = 20000; *val2 = priv->shunt_resistor_uohm; } else { /* * processed (mV) = raw * voltage_lsb (mV) * voltage_lsb (mV) = 2048 / 4096 */ *val = 2048; *val2 = 4096; } return IIO_VAL_FRACTIONAL; default: return -EINVAL; } } static int lmp92064_reset(struct lmp92064_adc_priv *priv, struct gpio_desc *gpio_reset) { unsigned int status; int ret, i; if (gpio_reset) { /* * Perform a hard reset if gpio_reset is available. * The datasheet specifies a very low 3.5ns reset pulse duration and does not * specify how long to wait after a reset to access the device. * Use more conservative pulse lengths to allow analog RC filtering of the * reset line at the board level (as recommended in the datasheet). */ gpiod_set_value_cansleep(gpio_reset, 1); usleep_range(1, 10); gpiod_set_value_cansleep(gpio_reset, 0); usleep_range(500, 750); } else { /* * Perform a soft-reset if not. * Also write default values to the config registers that are not * affected by soft reset. */ ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_A, TI_LMP92064_VAL_CONFIG_A); if (ret < 0) return ret; ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_B, TI_LMP92064_VAL_CONFIG_B); if (ret < 0) return ret; } /* * Wait for the device to signal readiness to prevent reading bogus data * and make sure device is actually connected. * The datasheet does not specify how long this takes but usually it is * not more than 3-4 iterations of this loop. */ for (i = 0; i < 10; i++) { ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status); if (ret < 0) return ret; if (status == TI_LMP92064_VAL_STATUS_OK) return 0; usleep_range(1000, 2000); } /* * No (correct) response received. * Device is mostly likely not connected to the bus. */ return -ENXIO; } static const struct iio_info lmp92064_adc_info = { .read_raw = lmp92064_read_raw, }; static int lmp92064_adc_probe(struct spi_device *spi) { struct device *dev = &spi->dev; struct lmp92064_adc_priv *priv; struct gpio_desc *gpio_reset; struct iio_dev *indio_dev; u32 shunt_resistor_uohm; struct regmap *regmap; int ret; ret = spi_setup(spi); if (ret < 0) return dev_err_probe(dev, ret, "Error in SPI setup\n"); regmap = devm_regmap_init_spi(spi, &lmp92064_spi_regmap_config); if (IS_ERR(regmap)) return dev_err_probe(dev, PTR_ERR(regmap), "Failed to set up SPI regmap\n"); indio_dev = devm_iio_device_alloc(dev, sizeof(*priv)); if (!indio_dev) return -ENOMEM; priv = iio_priv(indio_dev); priv->spi = spi; priv->regmap = regmap; ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms", &shunt_resistor_uohm); if (ret < 0) return dev_err_probe(dev, ret, "Failed to get shunt-resistor value\n"); /* * The shunt resistance is passed to userspace as the denominator of an iio * fraction. Make sure it is in range for that. */ if (shunt_resistor_uohm == 0 || shunt_resistor_uohm > INT_MAX) { dev_err(dev, "Shunt resistance is out of range\n"); return -EINVAL; } priv->shunt_resistor_uohm = shunt_resistor_uohm; ret = devm_regulator_get_enable(dev, "vdd"); if (ret) return ret; ret = devm_regulator_get_enable(dev, "vdig"); if (ret) return ret; gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(gpio_reset)) return dev_err_probe(dev, PTR_ERR(gpio_reset), "Failed to get GPIO reset pin\n"); ret = lmp92064_reset(priv, gpio_reset); if (ret < 0) return dev_err_probe(dev, ret, "Failed to reset device\n"); indio_dev->name = "lmp92064"; indio_dev->modes = INDIO_DIRECT_MODE; indio_dev->channels = lmp92064_adc_channels; indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels); indio_dev->info = &lmp92064_adc_info; return devm_iio_device_register(dev, indio_dev); } static const struct spi_device_id lmp92064_id_table[] = { { "lmp92064" }, {} }; MODULE_DEVICE_TABLE(spi, lmp92064_id_table); static const struct of_device_id lmp92064_of_table[] = { { .compatible = "ti,lmp92064" }, {} }; MODULE_DEVICE_TABLE(of, lmp92064_of_table); static struct spi_driver lmp92064_adc_driver = { .driver = { .name = "lmp92064", .of_match_table = lmp92064_of_table, }, .probe = lmp92064_adc_probe, .id_table = lmp92064_id_table, }; module_spi_driver(lmp92064_adc_driver); MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>"); MODULE_DESCRIPTION("TI LMP92064 ADC"); MODULE_LICENSE("GPL");