diff options
Diffstat (limited to 'drivers/iio/potentiometer/max5487.c')
| -rw-r--r-- | drivers/iio/potentiometer/max5487.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/drivers/iio/potentiometer/max5487.c b/drivers/iio/potentiometer/max5487.c new file mode 100644 index 000000000..5042d3e09 --- /dev/null +++ b/drivers/iio/potentiometer/max5487.c @@ -0,0 +1,159 @@ +/* + * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers + * + * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ +#include <linux/module.h> +#include <linux/spi/spi.h> +#include <linux/acpi.h> + +#include <linux/iio/sysfs.h> +#include <linux/iio/iio.h> + +#define MAX5487_WRITE_WIPER_A (0x01 << 8) +#define MAX5487_WRITE_WIPER_B (0x02 << 8) + +/* copy both wiper regs to NV regs */ +#define MAX5487_COPY_AB_TO_NV (0x23 << 8) +/* copy both NV regs to wiper regs */ +#define MAX5487_COPY_NV_TO_AB (0x33 << 8) + +#define MAX5487_MAX_POS 255 + +struct max5487_data { + struct spi_device *spi; + int kohms; +}; + +#define MAX5487_CHANNEL(ch, addr) { \ + .type = IIO_RESISTANCE, \ + .indexed = 1, \ + .output = 1, \ + .channel = ch, \ + .address = addr, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ +} + +static const struct iio_chan_spec max5487_channels[] = { + MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A), + MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B), +}; + +static int max5487_write_cmd(struct spi_device *spi, u16 cmd) +{ + return spi_write(spi, (const void *) &cmd, sizeof(u16)); +} + +static int max5487_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max5487_data *data = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_SCALE) + return -EINVAL; + + *val = 1000 * data->kohms; + *val2 = MAX5487_MAX_POS; + + return IIO_VAL_FRACTIONAL; +} + +static int max5487_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct max5487_data *data = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_RAW) + return -EINVAL; + + if (val < 0 || val > MAX5487_MAX_POS) + return -EINVAL; + + return max5487_write_cmd(data->spi, chan->address | val); +} + +static const struct iio_info max5487_info = { + .read_raw = max5487_read_raw, + .write_raw = max5487_write_raw, +}; + +static int max5487_spi_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct max5487_data *data; + const struct spi_device_id *id = spi_get_device_id(spi); + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + dev_set_drvdata(&spi->dev, indio_dev); + data = iio_priv(indio_dev); + + data->spi = spi; + data->kohms = id->driver_data; + + indio_dev->info = &max5487_info; + indio_dev->name = id->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = max5487_channels; + indio_dev->num_channels = ARRAY_SIZE(max5487_channels); + + /* restore both wiper regs from NV regs */ + ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB); + if (ret < 0) + return ret; + + return iio_device_register(indio_dev); +} + +static int max5487_spi_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev); + + iio_device_unregister(indio_dev); + + /* save both wiper regs to NV regs */ + return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV); +} + +static const struct spi_device_id max5487_id[] = { + { "MAX5487", 10 }, + { "MAX5488", 50 }, + { "MAX5489", 100 }, + { } +}; +MODULE_DEVICE_TABLE(spi, max5487_id); + +static const struct acpi_device_id max5487_acpi_match[] = { + { "MAX5487", 10 }, + { "MAX5488", 50 }, + { "MAX5489", 100 }, + { }, +}; +MODULE_DEVICE_TABLE(acpi, max5487_acpi_match); + +static struct spi_driver max5487_driver = { + .driver = { + .name = "max5487", + .acpi_match_table = ACPI_PTR(max5487_acpi_match), + }, + .id_table = max5487_id, + .probe = max5487_spi_probe, + .remove = max5487_spi_remove +}; +module_spi_driver(max5487_driver); + +MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>"); +MODULE_DESCRIPTION("max5487 SPI driver"); +MODULE_LICENSE("GPL v2"); |