diff options
Diffstat (limited to 'drivers/iio/adc/mcp3422.c')
| -rw-r--r-- | drivers/iio/adc/mcp3422.c | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c new file mode 100644 index 0000000..1294832 --- /dev/null +++ b/drivers/iio/adc/mcp3422.c @@ -0,0 +1,410 @@ +/* + * mcp3422.c - driver for the Microchip mcp3422/3/4 chip family + * + * Copyright (C) 2013, Angelo Compagnucci + * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com> + * + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf + * + * This driver exports the value of analog input voltage to sysfs, the + * voltage unit is nV. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/module.h> +#include <linux/delay.h> +#include <linux/sysfs.h> +#include <linux/of.h> + +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> + +/* Masks */ +#define MCP3422_CHANNEL_MASK 0x60 +#define MCP3422_PGA_MASK 0x03 +#define MCP3422_SRATE_MASK 0x0C +#define MCP3422_SRATE_240 0x0 +#define MCP3422_SRATE_60 0x1 +#define MCP3422_SRATE_15 0x2 +#define MCP3422_SRATE_3 0x3 +#define MCP3422_PGA_1 0 +#define MCP3422_PGA_2 1 +#define MCP3422_PGA_4 2 +#define MCP3422_PGA_8 3 +#define MCP3422_CONT_SAMPLING 0x10 + +#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5) +#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK) +#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2) + +#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK) +#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK) +#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK) + +#define MCP3422_CHAN(_index) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = _index, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \ + | BIT(IIO_CHAN_INFO_SCALE), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \ + } + +/* LSB is in nV to eliminate floating point */ +static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625}; + +/* + * scales calculated as: + * rates_to_lsb[sample_rate] / (1 << pga); + * pga is 1 for 0, 2 + */ + +static const int mcp3422_scales[4][4] = { + { 1000000, 250000, 62500, 15625 }, + { 500000 , 125000, 31250, 7812 }, + { 250000 , 62500 , 15625, 3906 }, + { 125000 , 31250 , 7812 , 1953 } }; + +/* Constant msleep times for data acquisitions */ +static const int mcp3422_read_times[4] = { + [MCP3422_SRATE_240] = 1000 / 240, + [MCP3422_SRATE_60] = 1000 / 60, + [MCP3422_SRATE_15] = 1000 / 15, + [MCP3422_SRATE_3] = 1000 / 3 }; + +/* sample rates to integer conversion table */ +static const int mcp3422_sample_rates[4] = { + [MCP3422_SRATE_240] = 240, + [MCP3422_SRATE_60] = 60, + [MCP3422_SRATE_15] = 15, + [MCP3422_SRATE_3] = 3 }; + +/* sample rates to sign extension table */ +static const int mcp3422_sign_extend[4] = { + [MCP3422_SRATE_240] = 12, + [MCP3422_SRATE_60] = 14, + [MCP3422_SRATE_15] = 16, + [MCP3422_SRATE_3] = 18 }; + +/* Client data (each client gets its own) */ +struct mcp3422 { + struct i2c_client *i2c; + u8 config; + u8 pga[4]; + struct mutex lock; +}; + +static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig) +{ + int ret; + + mutex_lock(&adc->lock); + + ret = i2c_master_send(adc->i2c, &newconfig, 1); + if (ret > 0) { + adc->config = newconfig; + ret = 0; + } + + mutex_unlock(&adc->lock); + + return ret; +} + +static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config) +{ + int ret = 0; + u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config); + u8 buf[4] = {0, 0, 0, 0}; + u32 temp; + + if (sample_rate == MCP3422_SRATE_3) { + ret = i2c_master_recv(adc->i2c, buf, 4); + temp = buf[0] << 16 | buf[1] << 8 | buf[2]; + *config = buf[3]; + } else { + ret = i2c_master_recv(adc->i2c, buf, 3); + temp = buf[0] << 8 | buf[1]; + *config = buf[2]; + } + + *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]); + + return ret; +} + +static int mcp3422_read_channel(struct mcp3422 *adc, + struct iio_chan_spec const *channel, int *value) +{ + int ret; + u8 config; + u8 req_channel = channel->channel; + + if (req_channel != MCP3422_CHANNEL(adc->config)) { + config = adc->config; + config &= ~MCP3422_CHANNEL_MASK; + config |= MCP3422_CHANNEL_VALUE(req_channel); + config &= ~MCP3422_PGA_MASK; + config |= MCP3422_PGA_VALUE(adc->pga[req_channel]); + ret = mcp3422_update_config(adc, config); + if (ret < 0) + return ret; + msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]); + } + + return mcp3422_read(adc, value, &config); +} + +static int mcp3422_read_raw(struct iio_dev *iio, + struct iio_chan_spec const *channel, int *val1, + int *val2, long mask) +{ + struct mcp3422 *adc = iio_priv(iio); + int err; + + u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config); + u8 pga = MCP3422_PGA(adc->config); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + err = mcp3422_read_channel(adc, channel, val1); + if (err < 0) + return -EINVAL; + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + + *val1 = 0; + *val2 = mcp3422_scales[sample_rate][pga]; + return IIO_VAL_INT_PLUS_NANO; + + case IIO_CHAN_INFO_SAMP_FREQ: + *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)]; + return IIO_VAL_INT; + + default: + break; + } + + return -EINVAL; +} + +static int mcp3422_write_raw(struct iio_dev *iio, + struct iio_chan_spec const *channel, int val1, + int val2, long mask) +{ + struct mcp3422 *adc = iio_priv(iio); + u8 temp; + u8 config = adc->config; + u8 req_channel = channel->channel; + u8 sample_rate = MCP3422_SAMPLE_RATE(config); + u8 i; + + switch (mask) { + case IIO_CHAN_INFO_SCALE: + if (val1 != 0) + return -EINVAL; + + for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) { + if (val2 == mcp3422_scales[sample_rate][i]) { + adc->pga[req_channel] = i; + + config &= ~MCP3422_CHANNEL_MASK; + config |= MCP3422_CHANNEL_VALUE(req_channel); + config &= ~MCP3422_PGA_MASK; + config |= MCP3422_PGA_VALUE(adc->pga[req_channel]); + + return mcp3422_update_config(adc, config); + } + } + return -EINVAL; + + case IIO_CHAN_INFO_SAMP_FREQ: + switch (val1) { + case 240: + temp = MCP3422_SRATE_240; + break; + case 60: + temp = MCP3422_SRATE_60; + break; + case 15: + temp = MCP3422_SRATE_15; + break; + case 3: + temp = MCP3422_SRATE_3; + break; + default: + return -EINVAL; + } + + config &= ~MCP3422_CHANNEL_MASK; + config |= MCP3422_CHANNEL_VALUE(req_channel); + config &= ~MCP3422_SRATE_MASK; + config |= MCP3422_SAMPLE_RATE_VALUE(temp); + + return mcp3422_update_config(adc, config); + + default: + break; + } + + return -EINVAL; +} + +static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, long mask) +{ + switch (mask) { + case IIO_CHAN_INFO_SCALE: + return IIO_VAL_INT_PLUS_NANO; + case IIO_CHAN_INFO_SAMP_FREQ: + return IIO_VAL_INT_PLUS_MICRO; + default: + return -EINVAL; + } +} + +static ssize_t mcp3422_show_scales(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev)); + u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config); + + return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n", + mcp3422_scales[sample_rate][0], + mcp3422_scales[sample_rate][1], + mcp3422_scales[sample_rate][2], + mcp3422_scales[sample_rate][3]); +} + +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3"); +static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO, + mcp3422_show_scales, NULL, 0); + +static struct attribute *mcp3422_attributes[] = { + &iio_const_attr_sampling_frequency_available.dev_attr.attr, + &iio_dev_attr_in_voltage_scale_available.dev_attr.attr, + NULL, +}; + +static const struct attribute_group mcp3422_attribute_group = { + .attrs = mcp3422_attributes, +}; + +static const struct iio_chan_spec mcp3422_channels[] = { + MCP3422_CHAN(0), + MCP3422_CHAN(1), +}; + +static const struct iio_chan_spec mcp3424_channels[] = { + MCP3422_CHAN(0), + MCP3422_CHAN(1), + MCP3422_CHAN(2), + MCP3422_CHAN(3), +}; + +static const struct iio_info mcp3422_info = { + .read_raw = mcp3422_read_raw, + .write_raw = mcp3422_write_raw, + .write_raw_get_fmt = mcp3422_write_raw_get_fmt, + .attrs = &mcp3422_attribute_group, + .driver_module = THIS_MODULE, +}; + +static int mcp3422_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct iio_dev *indio_dev; + struct mcp3422 *adc; + int err; + u8 config; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->i2c = client; + + mutex_init(&adc->lock); + + indio_dev->dev.parent = &client->dev; + indio_dev->name = dev_name(&client->dev); + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &mcp3422_info; + + switch ((unsigned int)(id->driver_data)) { + case 2: + case 3: + indio_dev->channels = mcp3422_channels; + indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels); + break; + case 4: + indio_dev->channels = mcp3424_channels; + indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels); + break; + } + + /* meaningful default configuration */ + config = (MCP3422_CONT_SAMPLING + | MCP3422_CHANNEL_VALUE(1) + | MCP3422_PGA_VALUE(MCP3422_PGA_1) + | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240)); + mcp3422_update_config(adc, config); + + err = iio_device_register(indio_dev); + if (err < 0) + return err; + + i2c_set_clientdata(client, indio_dev); + + return 0; +} + +static int mcp3422_remove(struct i2c_client *client) +{ + iio_device_unregister(i2c_get_clientdata(client)); + return 0; +} + +static const struct i2c_device_id mcp3422_id[] = { + { "mcp3422", 2 }, + { "mcp3423", 3 }, + { "mcp3424", 4 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, mcp3422_id); + +#ifdef CONFIG_OF +static const struct of_device_id mcp3422_of_match[] = { + { .compatible = "mcp3422" }, + { } +}; +MODULE_DEVICE_TABLE(of, mcp3422_of_match); +#endif + +static struct i2c_driver mcp3422_driver = { + .driver = { + .name = "mcp3422", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(mcp3422_of_match), + }, + .probe = mcp3422_probe, + .remove = mcp3422_remove, + .id_table = mcp3422_id, +}; +module_i2c_driver(mcp3422_driver); + +MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>"); +MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver"); +MODULE_LICENSE("GPL v2"); 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