Hello people, The MCP3422/3/4 chip family is an high resolution ADC (18 bits) from Microchip with an I2C interface. It has variable resolution (12, 14, 16, 18 bits) which determines the sampling frequency (240, 60, 15, 5 samples/sec), a variable gain (1x, 2x, 4x, 8x) and a variable number of input channels (2-4) depending on the chip version. Signed-off-by: Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index 93129ec..12c26a9 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -167,4 +167,14 @@ config VIPERBOARD_ADC Say yes here to access the ADC part of the Nano River Technologies Viperboard. +config MCP3422 + tristate "Microchip Technology MCP3422/3/4 driver" + depends on I2C + help + Say yes here to build support for Microchip Technology's MCP3422, + MCP3423 or MCP3424 analog to digital converters. + + This driver can also be built as a module. If so, the module will be + called mcp3422. + endmenu diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile index 8f475d3..416923d 100644 --- a/drivers/iio/adc/Makefile +++ b/drivers/iio/adc/Makefile @@ -18,3 +18,4 @@ obj-$(CONFIG_MCP320X) += mcp320x.o obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o +obj-$(CONFIG_MCP3422) += mcp3422.o diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c new file mode 100644 index 0000000..f6c6802 --- /dev/null +++ b/drivers/iio/adc/mcp3422.c @@ -0,0 +1,400 @@ +/* + * mcp3422.c - driver for the Microchip mcp3422/3/4 chip family + * + * Copyright (C) 2013, Angelo Compagnucci + * Author: Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx> + * + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf + * + * This driver export 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/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_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 VREF 2048 + +#define MCP3422_CHAN(index) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = index, \ + .address = index, \ + .scan_index = index, \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + } + +/* LSB is in nV to eliminate floating point */ +static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625}; + +/* + * Client data (each client gets its own) + */ +struct mcp3422 { + struct i2c_client *i2c; + u8 config; +}; + +static int mcp3422_update_config(struct mcp3422 *adc) +{ + u8 buf[1]; + buf[0] = adc->config; + return i2c_master_send(adc->i2c, buf, 1); +} + +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'}; + + *value = 0; + + if (sample_rate == MCP3422_SRATE_3) { + ret = i2c_master_recv(adc->i2c, buf, 4); + *value += (s8)buf[0]; + *value <<= 16; + *value |= buf[1] << 8; + *value |= buf[2]; + *config = buf[3]; + if (*value == 0xFFFFFFFF) + *value = 0; + } else { + ret = i2c_master_recv(adc->i2c, buf, 3); + *value += (s8)buf[0]; + *value <<= 8; + *value |= buf[1]; + *config = buf[2]; + } + + return ret; +} + +static int mcp3422_read_channel(struct mcp3422 *adc, + struct iio_chan_spec const *channel, int *value) +{ + int ret, mtime = 0; + u8 current_config = 0; + u8 req_channel = channel->channel - 1; + + ret = mcp3422_read(adc, value, ¤t_config); + + if (req_channel != MCP3422_CHANNEL(current_config)) { + adc->config &= ~MCP3422_CHANNEL_MASK; + adc->config |= ((req_channel << 5) & MCP3422_CHANNEL_MASK); + mcp3422_update_config(adc); + switch (MCP3422_SAMPLE_RATE(current_config)) { + case MCP3422_SRATE_240: + mtime = 1000 / 240; + break; + case MCP3422_SRATE_60: + mtime = 1000 / 60; + break; + case MCP3422_SRATE_15: + mtime = 1000 / 15; + break; + case MCP3422_SRATE_3: + mtime = 1000 / 3; + break; + } + msleep(mtime); + ret = mcp3422_read(adc, value, ¤t_config); + } + return ret; +} + +static int mcp3422_read_raw(struct iio_dev *iio, + struct iio_chan_spec const *channel, int *value, + int *shift, long mask) +{ + struct mcp3422 *adc = iio_priv(iio); + int err, temp = 0; + + 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, &temp); + if (err < 0) + return err; + + /* + * Converting the output + */ + *value = (temp * rates_to_lsb[sample_rate]) + / (pga ? 1 << pga : 1); + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + + *value = VREF * 1000000; + + return IIO_VAL_INT; + + default: + break; + } + + return -EINVAL; +} + +static ssize_t mcp3422_set_sample_rate(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct i2c_client *client = to_i2c_client(dev); + struct iio_dev *iio = i2c_get_clientdata(client); + struct mcp3422 *adc = iio_priv(iio); + u8 value = 0; + + if (kstrtou8(buf, 10, &value) < 0) + return -EINVAL; + + switch (value) { + case 240: + value = MCP3422_SRATE_240; + break; + case 60: + value = MCP3422_SRATE_60; + break; + case 15: + value = MCP3422_SRATE_15; + break; + case 3: + value = MCP3422_SRATE_3; + break; + default: + return -EINVAL; + } + + adc->config &= ~MCP3422_SRATE_MASK; + adc->config |= ((value << 2) & MCP3422_SRATE_MASK); + + mcp3422_update_config(adc); + + return count; +} + +static ssize_t mcp3422_get_sample_rate(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct iio_dev *iio = i2c_get_clientdata(client); + struct mcp3422 *adc = iio_priv(iio); + u8 value = 0; + + switch (MCP3422_SAMPLE_RATE(adc->config)) { + case 0: + value = 240; + break; + case 1: + value = 60; + break; + case 2: + value = 15; + break; + case 3: + value = 3; + break; + } + + return sprintf(buf, "%d\n", value); +} + +static ssize_t mcp3422_set_pga(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct i2c_client *client = to_i2c_client(dev); + struct iio_dev *iio = i2c_get_clientdata(client); + struct mcp3422 *adc = iio_priv(iio); + u8 value = 0; + + if (kstrtou8(buf, 10, &value) < 0) + return -EINVAL; + + switch (value) { + case 1: + value = 0; + break; + case 2: + value = 1; + break; + case 4: + value = 2; + break; + case 8: + value = 3; + break; + default: + return -EINVAL; + } + + adc->config &= ~MCP3422_PGA_MASK; + adc->config |= (value & MCP3422_PGA_MASK); + + mcp3422_update_config(adc); + + return count; +} + +static ssize_t mcp3422_get_pga(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct iio_dev *iio = i2c_get_clientdata(client); + struct mcp3422 *adc = iio_priv(iio); + + return sprintf(buf, "%d\n", 1 << MCP3422_PGA(adc->config)); +} + +static IIO_DEV_ATTR_SAMP_FREQ(S_IRUGO | S_IWUSR, + mcp3422_get_sample_rate, + mcp3422_set_sample_rate); +static IIO_DEVICE_ATTR(pga, + S_IRUGO | S_IWUSR, + mcp3422_get_pga, + mcp3422_set_pga, 0); +static IIO_CONST_ATTR(sampling_frequency_available, "240 60 15 3"); +static IIO_CONST_ATTR(pga_available, "1 2 4 8"); + +static struct attribute *mcp3422_attributes[] = { + &iio_dev_attr_sampling_frequency.dev_attr.attr, + &iio_const_attr_sampling_frequency_available.dev_attr.attr, + &iio_dev_attr_pga.dev_attr.attr, + &iio_const_attr_pga_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(1), + MCP3422_CHAN(2), + MCP3422_CHAN(3), + MCP3422_CHAN(4), +}; + +static const struct iio_info mcp3422_info = { + .read_raw = mcp3422_read_raw, + .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 *iio; + struct mcp3422 *adc; + int err; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA)) + return -ENODEV; + + iio = iio_device_alloc(sizeof(*adc)); + if (!iio) + return -ENOMEM; + + adc = iio_priv(iio); + adc->i2c = client; + + /* meaningful default configuration */ + adc->config = 0x10; + + iio->dev.parent = &client->dev; + iio->name = dev_name(&client->dev); + iio->modes = INDIO_DIRECT_MODE; + iio->info = &mcp3422_info; + + iio->channels = mcp3422_channels; + iio->num_channels = ARRAY_SIZE(mcp3422_channels); + + err = iio_device_register(iio); + if (err < 0) + goto iio_free; + + i2c_set_clientdata(client, iio); + + mcp3422_update_config(adc); + + return 0; + +iio_free: + iio_device_free(iio); + + return err; +} + +static int mcp3422_remove(struct i2c_client *client) +{ + struct iio_dev *iio = i2c_get_clientdata(client); + + iio_device_unregister(iio); + iio_device_free(iio); + + 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@xxxxxxxxx>"); +MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver"); +MODULE_LICENSE("GPL v2"); -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
