1 // SPDX-License-Identifier: GPL-2.0
3 * Texas Instruments LMP92064 SPI ADC driver
5 * Copyright (c) 2022 Leonard Göhrs <kernel@pengutronix.de>, Pengutronix
7 * Based on linux/drivers/iio/adc/ti-tsc2046.c
8 * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix
11 #include <linux/delay.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/module.h>
14 #include <linux/regmap.h>
15 #include <linux/regulator/consumer.h>
16 #include <linux/spi/spi.h>
18 #include <linux/iio/iio.h>
19 #include <linux/iio/driver.h>
21 #define TI_LMP92064_REG_CONFIG_A 0x0000
22 #define TI_LMP92064_REG_CONFIG_B 0x0001
23 #define TI_LMP92064_REG_CHIP_REV 0x0006
25 #define TI_LMP92064_REG_MFR_ID1 0x000C
26 #define TI_LMP92064_REG_MFR_ID2 0x000D
28 #define TI_LMP92064_REG_REG_UPDATE 0x000F
29 #define TI_LMP92064_REG_CONFIG_REG 0x0100
30 #define TI_LMP92064_REG_STATUS 0x0103
32 #define TI_LMP92064_REG_DATA_VOUT_LSB 0x0200
33 #define TI_LMP92064_REG_DATA_VOUT_MSB 0x0201
34 #define TI_LMP92064_REG_DATA_COUT_LSB 0x0202
35 #define TI_LMP92064_REG_DATA_COUT_MSB 0x0203
37 #define TI_LMP92064_VAL_CONFIG_A 0x99
38 #define TI_LMP92064_VAL_CONFIG_B 0x00
39 #define TI_LMP92064_VAL_STATUS_OK 0x01
42 * Channel number definitions for the two channels of the device
46 #define TI_LMP92064_CHAN_INC 0
47 #define TI_LMP92064_CHAN_INV 1
49 static const struct regmap_range lmp92064_readable_reg_ranges[] = {
50 regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CHIP_REV),
51 regmap_reg_range(TI_LMP92064_REG_MFR_ID1, TI_LMP92064_REG_MFR_ID2),
52 regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
53 regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
54 regmap_reg_range(TI_LMP92064_REG_STATUS, TI_LMP92064_REG_STATUS),
55 regmap_reg_range(TI_LMP92064_REG_DATA_VOUT_LSB, TI_LMP92064_REG_DATA_COUT_MSB),
58 static const struct regmap_access_table lmp92064_readable_regs = {
59 .yes_ranges = lmp92064_readable_reg_ranges,
60 .n_yes_ranges = ARRAY_SIZE(lmp92064_readable_reg_ranges),
63 static const struct regmap_range lmp92064_writable_reg_ranges[] = {
64 regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CONFIG_B),
65 regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
66 regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
69 static const struct regmap_access_table lmp92064_writable_regs = {
70 .yes_ranges = lmp92064_writable_reg_ranges,
71 .n_yes_ranges = ARRAY_SIZE(lmp92064_writable_reg_ranges),
74 static const struct regmap_config lmp92064_spi_regmap_config = {
77 .max_register = TI_LMP92064_REG_DATA_COUT_MSB,
78 .rd_table = &lmp92064_readable_regs,
79 .wr_table = &lmp92064_writable_regs,
82 struct lmp92064_adc_priv {
83 int shunt_resistor_uohm;
84 struct spi_device *spi;
85 struct regmap *regmap;
88 static const struct iio_chan_spec lmp92064_adc_channels[] = {
91 .address = TI_LMP92064_CHAN_INC,
93 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
94 .datasheet_name = "INC",
98 .address = TI_LMP92064_CHAN_INV,
100 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
101 .datasheet_name = "INV",
105 static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res)
111 * The ADC only latches in new samples if all DATA registers are read
112 * in descending sequential order.
113 * The ADC auto-decrements the register index with each clocked byte.
114 * Read both channels in single SPI transfer by selecting the highest
115 * register using the command below and clocking out all four data
119 ret = regmap_bulk_read(priv->regmap, TI_LMP92064_REG_DATA_COUT_MSB,
123 dev_err(&priv->spi->dev, "regmap_bulk_read failed: %pe\n",
128 res[0] = be16_to_cpu(raw[0]);
129 res[1] = be16_to_cpu(raw[1]);
134 static int lmp92064_read_raw(struct iio_dev *indio_dev,
135 struct iio_chan_spec const *chan, int *val,
136 int *val2, long mask)
138 struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
143 case IIO_CHAN_INFO_RAW:
144 ret = lmp92064_read_meas(priv, raw);
148 *val = (chan->address == TI_LMP92064_CHAN_INC) ? raw[0] : raw[1];
151 case IIO_CHAN_INFO_SCALE:
152 if (chan->address == TI_LMP92064_CHAN_INC) {
154 * processed (mA) = raw * current_lsb (mA)
155 * current_lsb (mA) = shunt_voltage_lsb (nV) / shunt_resistor (uOhm)
156 * shunt_voltage_lsb (nV) = 81920000 / 4096 = 20000
159 *val2 = priv->shunt_resistor_uohm;
162 * processed (mV) = raw * voltage_lsb (mV)
163 * voltage_lsb (mV) = 2048 / 4096
168 return IIO_VAL_FRACTIONAL;
174 static int lmp92064_reset(struct lmp92064_adc_priv *priv,
175 struct gpio_desc *gpio_reset)
182 * Perform a hard reset if gpio_reset is available.
183 * The datasheet specifies a very low 3.5ns reset pulse duration and does not
184 * specify how long to wait after a reset to access the device.
185 * Use more conservative pulse lengths to allow analog RC filtering of the
186 * reset line at the board level (as recommended in the datasheet).
188 gpiod_set_value_cansleep(gpio_reset, 1);
190 gpiod_set_value_cansleep(gpio_reset, 0);
191 usleep_range(500, 750);
194 * Perform a soft-reset if not.
195 * Also write default values to the config registers that are not
196 * affected by soft reset.
198 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_A,
199 TI_LMP92064_VAL_CONFIG_A);
203 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_B,
204 TI_LMP92064_VAL_CONFIG_B);
210 * Wait for the device to signal readiness to prevent reading bogus data
211 * and make sure device is actually connected.
212 * The datasheet does not specify how long this takes but usually it is
213 * not more than 3-4 iterations of this loop.
215 for (i = 0; i < 10; i++) {
216 ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status);
220 if (status == TI_LMP92064_VAL_STATUS_OK)
223 usleep_range(1000, 2000);
227 * No (correct) response received.
228 * Device is mostly likely not connected to the bus.
233 static const struct iio_info lmp92064_adc_info = {
234 .read_raw = lmp92064_read_raw,
237 static int lmp92064_adc_probe(struct spi_device *spi)
239 struct device *dev = &spi->dev;
240 struct lmp92064_adc_priv *priv;
241 struct gpio_desc *gpio_reset;
242 struct iio_dev *indio_dev;
243 u32 shunt_resistor_uohm;
244 struct regmap *regmap;
247 ret = spi_setup(spi);
249 return dev_err_probe(dev, ret, "Error in SPI setup\n");
251 regmap = devm_regmap_init_spi(spi, &lmp92064_spi_regmap_config);
253 return dev_err_probe(dev, PTR_ERR(regmap),
254 "Failed to set up SPI regmap\n");
256 indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
260 priv = iio_priv(indio_dev);
263 priv->regmap = regmap;
265 ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
266 &shunt_resistor_uohm);
268 return dev_err_probe(dev, ret,
269 "Failed to get shunt-resistor value\n");
272 * The shunt resistance is passed to userspace as the denominator of an iio
273 * fraction. Make sure it is in range for that.
275 if (shunt_resistor_uohm == 0 || shunt_resistor_uohm > INT_MAX) {
276 dev_err(dev, "Shunt resistance is out of range\n");
280 priv->shunt_resistor_uohm = shunt_resistor_uohm;
282 ret = devm_regulator_get_enable(dev, "vdd");
286 ret = devm_regulator_get_enable(dev, "vdig");
290 gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
291 if (IS_ERR(gpio_reset))
292 return dev_err_probe(dev, PTR_ERR(gpio_reset),
293 "Failed to get GPIO reset pin\n");
295 ret = lmp92064_reset(priv, gpio_reset);
297 return dev_err_probe(dev, ret, "Failed to reset device\n");
299 indio_dev->name = "lmp92064";
300 indio_dev->modes = INDIO_DIRECT_MODE;
301 indio_dev->channels = lmp92064_adc_channels;
302 indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels);
303 indio_dev->info = &lmp92064_adc_info;
305 return devm_iio_device_register(dev, indio_dev);
308 static const struct spi_device_id lmp92064_id_table[] = {
312 MODULE_DEVICE_TABLE(spi, lmp92064_id_table);
314 static const struct of_device_id lmp92064_of_table[] = {
315 { .compatible = "ti,lmp92064" },
318 MODULE_DEVICE_TABLE(of, lmp92064_of_table);
320 static struct spi_driver lmp92064_adc_driver = {
323 .of_match_table = lmp92064_of_table,
325 .probe = lmp92064_adc_probe,
326 .id_table = lmp92064_id_table,
328 module_spi_driver(lmp92064_adc_driver);
330 MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>");
331 MODULE_DESCRIPTION("TI LMP92064 ADC");
332 MODULE_LICENSE("GPL");