18a80a71dSAlexandru Lazar // SPDX-License-Identifier: GPL-2.0-only
28a80a71dSAlexandru Lazar /*
38a80a71dSAlexandru Lazar * MAX1241 low-power, 12-bit serial ADC
48a80a71dSAlexandru Lazar *
58a80a71dSAlexandru Lazar * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
68a80a71dSAlexandru Lazar */
78a80a71dSAlexandru Lazar
88a80a71dSAlexandru Lazar #include <linux/delay.h>
98a80a71dSAlexandru Lazar #include <linux/gpio/consumer.h>
108a80a71dSAlexandru Lazar #include <linux/iio/iio.h>
118a80a71dSAlexandru Lazar #include <linux/module.h>
128a80a71dSAlexandru Lazar #include <linux/regulator/consumer.h>
138a80a71dSAlexandru Lazar #include <linux/spi/spi.h>
148a80a71dSAlexandru Lazar
158a80a71dSAlexandru Lazar #define MAX1241_VAL_MASK GENMASK(11, 0)
168a80a71dSAlexandru Lazar #define MAX1241_SHUTDOWN_DELAY_USEC 4
178a80a71dSAlexandru Lazar
188a80a71dSAlexandru Lazar enum max1241_id {
198a80a71dSAlexandru Lazar max1241,
208a80a71dSAlexandru Lazar };
218a80a71dSAlexandru Lazar
228a80a71dSAlexandru Lazar struct max1241 {
238a80a71dSAlexandru Lazar struct spi_device *spi;
248a80a71dSAlexandru Lazar struct mutex lock;
258a80a71dSAlexandru Lazar struct regulator *vref;
268a80a71dSAlexandru Lazar struct gpio_desc *shutdown;
278a80a71dSAlexandru Lazar
289d7019e4SJonathan Cameron __be16 data __aligned(IIO_DMA_MINALIGN);
298a80a71dSAlexandru Lazar };
308a80a71dSAlexandru Lazar
318a80a71dSAlexandru Lazar static const struct iio_chan_spec max1241_channels[] = {
328a80a71dSAlexandru Lazar {
338a80a71dSAlexandru Lazar .type = IIO_VOLTAGE,
348a80a71dSAlexandru Lazar .indexed = 1,
358a80a71dSAlexandru Lazar .channel = 0,
368a80a71dSAlexandru Lazar .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
378a80a71dSAlexandru Lazar BIT(IIO_CHAN_INFO_SCALE),
388a80a71dSAlexandru Lazar },
398a80a71dSAlexandru Lazar };
408a80a71dSAlexandru Lazar
max1241_read(struct max1241 * adc)418a80a71dSAlexandru Lazar static int max1241_read(struct max1241 *adc)
428a80a71dSAlexandru Lazar {
438a80a71dSAlexandru Lazar struct spi_transfer xfers[] = {
448a80a71dSAlexandru Lazar /*
458a80a71dSAlexandru Lazar * Begin conversion by bringing /CS low for at least
468a80a71dSAlexandru Lazar * tconv us.
478a80a71dSAlexandru Lazar */
488a80a71dSAlexandru Lazar {
498a80a71dSAlexandru Lazar .len = 0,
508a80a71dSAlexandru Lazar .delay.value = 8,
518a80a71dSAlexandru Lazar .delay.unit = SPI_DELAY_UNIT_USECS,
528a80a71dSAlexandru Lazar },
538a80a71dSAlexandru Lazar /*
548a80a71dSAlexandru Lazar * Then read two bytes of data in our RX buffer.
558a80a71dSAlexandru Lazar */
568a80a71dSAlexandru Lazar {
578a80a71dSAlexandru Lazar .rx_buf = &adc->data,
588a80a71dSAlexandru Lazar .len = 2,
598a80a71dSAlexandru Lazar },
608a80a71dSAlexandru Lazar };
618a80a71dSAlexandru Lazar
628a80a71dSAlexandru Lazar return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
638a80a71dSAlexandru Lazar }
648a80a71dSAlexandru Lazar
max1241_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)658a80a71dSAlexandru Lazar static int max1241_read_raw(struct iio_dev *indio_dev,
668a80a71dSAlexandru Lazar struct iio_chan_spec const *chan,
678a80a71dSAlexandru Lazar int *val, int *val2, long mask)
688a80a71dSAlexandru Lazar {
698a80a71dSAlexandru Lazar int ret, vref_uV;
708a80a71dSAlexandru Lazar struct max1241 *adc = iio_priv(indio_dev);
718a80a71dSAlexandru Lazar
728a80a71dSAlexandru Lazar switch (mask) {
738a80a71dSAlexandru Lazar case IIO_CHAN_INFO_RAW:
748a80a71dSAlexandru Lazar mutex_lock(&adc->lock);
758a80a71dSAlexandru Lazar
768a80a71dSAlexandru Lazar if (adc->shutdown) {
778a80a71dSAlexandru Lazar gpiod_set_value(adc->shutdown, 0);
788a80a71dSAlexandru Lazar udelay(MAX1241_SHUTDOWN_DELAY_USEC);
798a80a71dSAlexandru Lazar ret = max1241_read(adc);
808a80a71dSAlexandru Lazar gpiod_set_value(adc->shutdown, 1);
818a80a71dSAlexandru Lazar } else
828a80a71dSAlexandru Lazar ret = max1241_read(adc);
838a80a71dSAlexandru Lazar
848a80a71dSAlexandru Lazar if (ret) {
858a80a71dSAlexandru Lazar mutex_unlock(&adc->lock);
868a80a71dSAlexandru Lazar return ret;
878a80a71dSAlexandru Lazar }
888a80a71dSAlexandru Lazar
898a80a71dSAlexandru Lazar *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
908a80a71dSAlexandru Lazar
918a80a71dSAlexandru Lazar mutex_unlock(&adc->lock);
928a80a71dSAlexandru Lazar return IIO_VAL_INT;
938a80a71dSAlexandru Lazar case IIO_CHAN_INFO_SCALE:
948a80a71dSAlexandru Lazar vref_uV = regulator_get_voltage(adc->vref);
958a80a71dSAlexandru Lazar
968a80a71dSAlexandru Lazar if (vref_uV < 0)
978a80a71dSAlexandru Lazar return vref_uV;
988a80a71dSAlexandru Lazar
998a80a71dSAlexandru Lazar *val = vref_uV / 1000;
1008a80a71dSAlexandru Lazar *val2 = 12;
1018a80a71dSAlexandru Lazar
1028a80a71dSAlexandru Lazar return IIO_VAL_FRACTIONAL_LOG2;
1038a80a71dSAlexandru Lazar default:
1048a80a71dSAlexandru Lazar return -EINVAL;
1058a80a71dSAlexandru Lazar }
1068a80a71dSAlexandru Lazar }
1078a80a71dSAlexandru Lazar
1088a80a71dSAlexandru Lazar static const struct iio_info max1241_info = {
1098a80a71dSAlexandru Lazar .read_raw = max1241_read_raw,
1108a80a71dSAlexandru Lazar };
1118a80a71dSAlexandru Lazar
max1241_disable_vref_action(void * data)1128a80a71dSAlexandru Lazar static void max1241_disable_vref_action(void *data)
1138a80a71dSAlexandru Lazar {
1148a80a71dSAlexandru Lazar struct max1241 *adc = data;
1158a80a71dSAlexandru Lazar struct device *dev = &adc->spi->dev;
1168a80a71dSAlexandru Lazar int err;
1178a80a71dSAlexandru Lazar
1188a80a71dSAlexandru Lazar err = regulator_disable(adc->vref);
1198a80a71dSAlexandru Lazar if (err)
1208a80a71dSAlexandru Lazar dev_err(dev, "could not disable vref regulator.\n");
1218a80a71dSAlexandru Lazar }
1228a80a71dSAlexandru Lazar
max1241_probe(struct spi_device * spi)1238a80a71dSAlexandru Lazar static int max1241_probe(struct spi_device *spi)
1248a80a71dSAlexandru Lazar {
1258a80a71dSAlexandru Lazar struct device *dev = &spi->dev;
1268a80a71dSAlexandru Lazar struct iio_dev *indio_dev;
1278a80a71dSAlexandru Lazar struct max1241 *adc;
1288a80a71dSAlexandru Lazar int ret;
1298a80a71dSAlexandru Lazar
1308a80a71dSAlexandru Lazar indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
1318a80a71dSAlexandru Lazar if (!indio_dev)
1328a80a71dSAlexandru Lazar return -ENOMEM;
1338a80a71dSAlexandru Lazar
1348a80a71dSAlexandru Lazar adc = iio_priv(indio_dev);
1358a80a71dSAlexandru Lazar adc->spi = spi;
1368a80a71dSAlexandru Lazar mutex_init(&adc->lock);
1378a80a71dSAlexandru Lazar
138*f55c8e66SMatti Vaittinen ret = devm_regulator_get_enable(dev, "vdd");
1398a80a71dSAlexandru Lazar if (ret)
140*f55c8e66SMatti Vaittinen return dev_err_probe(dev, ret,
141*f55c8e66SMatti Vaittinen "failed to get/enable vdd regulator\n");
1428a80a71dSAlexandru Lazar
1438a80a71dSAlexandru Lazar adc->vref = devm_regulator_get(dev, "vref");
144070a83ffSCai Huoqing if (IS_ERR(adc->vref))
145070a83ffSCai Huoqing return dev_err_probe(dev, PTR_ERR(adc->vref),
146070a83ffSCai Huoqing "failed to get vref regulator\n");
1478a80a71dSAlexandru Lazar
1488a80a71dSAlexandru Lazar ret = regulator_enable(adc->vref);
1498a80a71dSAlexandru Lazar if (ret)
1508a80a71dSAlexandru Lazar return ret;
1518a80a71dSAlexandru Lazar
1528a80a71dSAlexandru Lazar ret = devm_add_action_or_reset(dev, max1241_disable_vref_action, adc);
1538a80a71dSAlexandru Lazar if (ret) {
1548a80a71dSAlexandru Lazar dev_err(dev, "could not set up vref regulator cleanup action\n");
1558a80a71dSAlexandru Lazar return ret;
1568a80a71dSAlexandru Lazar }
1578a80a71dSAlexandru Lazar
1588a80a71dSAlexandru Lazar adc->shutdown = devm_gpiod_get_optional(dev, "shutdown",
1598a80a71dSAlexandru Lazar GPIOD_OUT_HIGH);
1608a80a71dSAlexandru Lazar if (IS_ERR(adc->shutdown))
161070a83ffSCai Huoqing return dev_err_probe(dev, PTR_ERR(adc->shutdown),
162070a83ffSCai Huoqing "cannot get shutdown gpio\n");
1638a80a71dSAlexandru Lazar
1648a80a71dSAlexandru Lazar if (adc->shutdown)
1658a80a71dSAlexandru Lazar dev_dbg(dev, "shutdown pin passed, low-power mode enabled");
1668a80a71dSAlexandru Lazar else
1678a80a71dSAlexandru Lazar dev_dbg(dev, "no shutdown pin passed, low-power mode disabled");
1688a80a71dSAlexandru Lazar
1698a80a71dSAlexandru Lazar indio_dev->name = spi_get_device_id(spi)->name;
1708a80a71dSAlexandru Lazar indio_dev->info = &max1241_info;
1718a80a71dSAlexandru Lazar indio_dev->modes = INDIO_DIRECT_MODE;
1728a80a71dSAlexandru Lazar indio_dev->channels = max1241_channels;
1738a80a71dSAlexandru Lazar indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
1748a80a71dSAlexandru Lazar
1758a80a71dSAlexandru Lazar return devm_iio_device_register(dev, indio_dev);
1768a80a71dSAlexandru Lazar }
1778a80a71dSAlexandru Lazar
1788a80a71dSAlexandru Lazar static const struct spi_device_id max1241_id[] = {
1798a80a71dSAlexandru Lazar { "max1241", max1241 },
1808a80a71dSAlexandru Lazar {}
1818a80a71dSAlexandru Lazar };
1828a80a71dSAlexandru Lazar
1838a80a71dSAlexandru Lazar static const struct of_device_id max1241_dt_ids[] = {
1848a80a71dSAlexandru Lazar { .compatible = "maxim,max1241" },
1858a80a71dSAlexandru Lazar {}
1868a80a71dSAlexandru Lazar };
1878a80a71dSAlexandru Lazar MODULE_DEVICE_TABLE(of, max1241_dt_ids);
1888a80a71dSAlexandru Lazar
1898a80a71dSAlexandru Lazar static struct spi_driver max1241_spi_driver = {
1908a80a71dSAlexandru Lazar .driver = {
1918a80a71dSAlexandru Lazar .name = "max1241",
1928a80a71dSAlexandru Lazar .of_match_table = max1241_dt_ids,
1938a80a71dSAlexandru Lazar },
1948a80a71dSAlexandru Lazar .probe = max1241_probe,
1958a80a71dSAlexandru Lazar .id_table = max1241_id,
1968a80a71dSAlexandru Lazar };
1978a80a71dSAlexandru Lazar module_spi_driver(max1241_spi_driver);
1988a80a71dSAlexandru Lazar
1998a80a71dSAlexandru Lazar MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>");
2008a80a71dSAlexandru Lazar MODULE_DESCRIPTION("MAX1241 ADC driver");
2018a80a71dSAlexandru Lazar MODULE_LICENSE("GPL v2");
202