diff options
Diffstat (limited to 'drivers/iio/adc/mcp320x.c')
| -rw-r--r-- | drivers/iio/adc/mcp320x.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/drivers/iio/adc/mcp320x.c b/drivers/iio/adc/mcp320x.c new file mode 100644 index 000000000000..ebc015922a79 --- /dev/null +++ b/drivers/iio/adc/mcp320x.c @@ -0,0 +1,257 @@ +/* + * Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com> + * + * Driver for Microchip Technology's MCP3204 and MCP3208 ADC chips. + * Datasheet can be found here: + * http://ww1.microchip.com/downloads/en/devicedoc/21298c.pdf + * + * 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/err.h> +#include <linux/spi/spi.h> +#include <linux/module.h> +#include <linux/iio/iio.h> +#include <linux/regulator/consumer.h> + +#define MCP_SINGLE_ENDED (1 << 3) +#define MCP_START_BIT (1 << 4) + +enum { + mcp3204, + mcp3208, +}; + +struct mcp320x { + struct spi_device *spi; + struct spi_message msg; + struct spi_transfer transfer[2]; + + u8 tx_buf; + u8 rx_buf[2]; + + struct regulator *reg; + struct mutex lock; +}; + +static int mcp320x_adc_conversion(struct mcp320x *adc, u8 msg) +{ + int ret; + + adc->tx_buf = msg; + ret = spi_sync(adc->spi, &adc->msg); + if (ret < 0) + return ret; + + return ((adc->rx_buf[0] & 0x3f) << 6) | + (adc->rx_buf[1] >> 2); +} + +static int mcp320x_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *channel, int *val, + int *val2, long mask) +{ + struct mcp320x *adc = iio_priv(indio_dev); + int ret = -EINVAL; + + mutex_lock(&adc->lock); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + if (channel->differential) + ret = mcp320x_adc_conversion(adc, + MCP_START_BIT | channel->address); + else + ret = mcp320x_adc_conversion(adc, + MCP_START_BIT | MCP_SINGLE_ENDED | + channel->address); + if (ret < 0) + goto out; + + *val = ret; + ret = IIO_VAL_INT; + break; + + case IIO_CHAN_INFO_SCALE: + /* Digital output code = (4096 * Vin) / Vref */ + ret = regulator_get_voltage(adc->reg); + if (ret < 0) + goto out; + + *val = ret / 1000; + *val2 = 12; + ret = IIO_VAL_FRACTIONAL_LOG2; + break; + + default: + break; + } + +out: + mutex_unlock(&adc->lock); + + return ret; +} + +#define MCP320X_VOLTAGE_CHANNEL(num) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (num), \ + .address = (num), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ + } + +#define MCP320X_VOLTAGE_CHANNEL_DIFF(num) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (num * 2), \ + .channel2 = (num * 2 + 1), \ + .address = (num * 2), \ + .differential = 1, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ + } + +static const struct iio_chan_spec mcp3204_channels[] = { + MCP320X_VOLTAGE_CHANNEL(0), + MCP320X_VOLTAGE_CHANNEL(1), + MCP320X_VOLTAGE_CHANNEL(2), + MCP320X_VOLTAGE_CHANNEL(3), + MCP320X_VOLTAGE_CHANNEL_DIFF(0), + MCP320X_VOLTAGE_CHANNEL_DIFF(1), +}; + +static const struct iio_chan_spec mcp3208_channels[] = { + MCP320X_VOLTAGE_CHANNEL(0), + MCP320X_VOLTAGE_CHANNEL(1), + MCP320X_VOLTAGE_CHANNEL(2), + MCP320X_VOLTAGE_CHANNEL(3), + MCP320X_VOLTAGE_CHANNEL(4), + MCP320X_VOLTAGE_CHANNEL(5), + MCP320X_VOLTAGE_CHANNEL(6), + MCP320X_VOLTAGE_CHANNEL(7), + MCP320X_VOLTAGE_CHANNEL_DIFF(0), + MCP320X_VOLTAGE_CHANNEL_DIFF(1), + MCP320X_VOLTAGE_CHANNEL_DIFF(2), + MCP320X_VOLTAGE_CHANNEL_DIFF(3), +}; + +static const struct iio_info mcp320x_info = { + .read_raw = mcp320x_read_raw, + .driver_module = THIS_MODULE, +}; + +struct mcp3208_chip_info { + const struct iio_chan_spec *channels; + unsigned int num_channels; +}; + +static const struct mcp3208_chip_info mcp3208_chip_infos[] = { + [mcp3204] = { + .channels = mcp3204_channels, + .num_channels = ARRAY_SIZE(mcp3204_channels) + }, + [mcp3208] = { + .channels = mcp3208_channels, + .num_channels = ARRAY_SIZE(mcp3208_channels) + }, +}; + +static int mcp320x_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct mcp320x *adc; + const struct mcp3208_chip_info *chip_info; + int ret; + + indio_dev = iio_device_alloc(sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + + indio_dev->dev.parent = &spi->dev; + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &mcp320x_info; + + chip_info = &mcp3208_chip_infos[spi_get_device_id(spi)->driver_data]; + indio_dev->channels = chip_info->channels; + indio_dev->num_channels = chip_info->num_channels; + + adc->transfer[0].tx_buf = &adc->tx_buf; + adc->transfer[0].len = sizeof(adc->tx_buf); + adc->transfer[1].rx_buf = adc->rx_buf; + adc->transfer[1].len = sizeof(adc->rx_buf); + + spi_message_init_with_transfers(&adc->msg, adc->transfer, + ARRAY_SIZE(adc->transfer)); + + adc->reg = regulator_get(&spi->dev, "vref"); + if (IS_ERR(adc->reg)) { + ret = PTR_ERR(adc->reg); + goto iio_free; + } + + ret = regulator_enable(adc->reg); + if (ret < 0) + goto reg_free; + + mutex_init(&adc->lock); + + ret = iio_device_register(indio_dev); + if (ret < 0) + goto reg_disable; + + return 0; + +reg_disable: + regulator_disable(adc->reg); +reg_free: + regulator_put(adc->reg); +iio_free: + iio_device_free(indio_dev); + + return ret; +} + +static int mcp320x_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct mcp320x *adc = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + regulator_disable(adc->reg); + regulator_put(adc->reg); + iio_device_free(indio_dev); + + return 0; +} + +static const struct spi_device_id mcp320x_id[] = { + { "mcp3204", mcp3204 }, + { "mcp3208", mcp3208 }, + { } +}; +MODULE_DEVICE_TABLE(spi, mcp320x_id); + +static struct spi_driver mcp320x_driver = { + .driver = { + .name = "mcp320x", + .owner = THIS_MODULE, + }, + .probe = mcp320x_probe, + .remove = mcp320x_remove, + .id_table = mcp320x_id, +}; +module_spi_driver(mcp320x_driver); + +MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>"); +MODULE_DESCRIPTION("Microchip Technology MCP3204/08"); +MODULE_LICENSE("GPL v2"); |