> Adds basic support for the LTC2485 ADC - a delta-sigma analog-to-digital > converter with an I2C interface that operates in single shot conversion > mode.
comments below, looks good > The driver supports an on board 5V reference and the power-on default > configuration which rejects both 50hz & 60hz line frequencies and > operates in 1x speed mode. > > Signed-off-by: Alison Schofield <[email protected]> > Cc: Daniel Baluta <[email protected]> > --- > > Reviewers: In addition to commenting on what is present, please comment > on what is absent and the priority in which you would like to see > additional features added to this driver, or needed in this first submittal. > > Not supported: > 1. External Vref > 2. Additional Configuration Modes > Temperature Sensor Mode: report temp data (not voltage). > > Line Frequency Rejection Mode: select to reject 50Hz or 60Hz > or both. (both is default) > > Speed Mode: Default speed mode (1x) performs two conversions each > cycle and combines the results. 2x speed mode only does one > conversion each cycle. > 3. Power management > 4. DT Bindings > 5. Triggered buffers > 6. What else? > > > drivers/iio/adc/Kconfig | 9 +++ > drivers/iio/adc/Makefile | 1 + > drivers/iio/adc/ltc2485.c | 150 > ++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 160 insertions(+) > create mode 100644 drivers/iio/adc/ltc2485.c > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index 1de31bd..a042611 100644 > --- a/drivers/iio/adc/Kconfig > +++ b/drivers/iio/adc/Kconfig > @@ -264,6 +264,15 @@ config LPC18XX_ADC > To compile this driver as a module, choose M here: the module will be > called lpc18xx_adc. > > +config LTC2485 > + tristate "Linear Technology LTC2485 ADC driver" > + depends on I2C > + help > + Say yes here to build support for Linear Technology LTC2485 ADC. > + > + To compile this driver as a module, choose M here: the module will be > + called ltc2485. > + > config MAX1027 > tristate "Maxim max1027 ADC driver" > depends on SPI > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile > index 0ba0d50..1be5747 100644 > --- a/drivers/iio/adc/Makefile > +++ b/drivers/iio/adc/Makefile > @@ -27,6 +27,7 @@ obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o > obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o > obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o > obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o > +obj-$(CONFIG_LTC2485) += ltc2485.o > obj-$(CONFIG_MAX1027) += max1027.o > obj-$(CONFIG_MAX1363) += max1363.o > obj-$(CONFIG_MCP320X) += mcp320x.o > diff --git a/drivers/iio/adc/ltc2485.c b/drivers/iio/adc/ltc2485.c > new file mode 100644 > index 0000000..a62778b > --- /dev/null > +++ b/drivers/iio/adc/ltc2485.c > @@ -0,0 +1,150 @@ > +/* > + * ltc2485.c - Driver for Linear Technology LTC2485 ADC > + * > + * Copyright (C) 2016 Alison Schofield <[email protected]> > + * > + * 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. > + * > + * Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf > + */ > + > +#include <linux/delay.h> > +#include <linux/i2c.h> > +#include <linux/module.h> > + > +#include <linux/iio/iio.h> > +#include <linux/iio/sysfs.h> > + > +/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */ > +#define LTC2485_CONFIG_DEFAULT 0 > + > +struct ltc2485_data { > + struct i2c_client *client; > + s64 time_prev; /* last conversion */ > +}; > + > +static void ltc2485_wait_conv(struct ltc2485_data *data) > +{ > + int conv_time = 147000000; /* conv time ns */ const maybe? > + s64 time_elapsed; > + > + /* delay if conversion time not passed since last read or write */ > + time_elapsed = ktime_get_real_ns() - data->time_prev; > + > + if (time_elapsed < conv_time) { > + usleep_range((conv_time - time_elapsed) / 1000, > + conv_time / 1000); > + } > +} > + > +static int ltc2485_read(struct ltc2485_data *data, int *val) > +{ > + struct i2c_client *client = data->client; > + __be32 buf = 0; > + int ret; > + > + ltc2485_wait_conv(data); > + > + ret = i2c_master_recv(client, (char *)&buf, 4); > + if (ret < 0) { > + dev_err(&client->dev, "i2c_master_recv failed\n"); > + return ret; > + } > + > + data->time_prev = ktime_get_real_ns(); > + *val = sign_extend32(be32_to_cpu(buf) >> 6, 24); > + > + return ret; > +} > + > +static int ltc2485_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int *val, int *val2, long mask) > +{ > + struct ltc2485_data *data = iio_priv(indio_dev); > + int ret; > + > + if (mask == IIO_CHAN_INFO_RAW) { > + ret = ltc2485_read(data, val); > + if (ret < 0) > + return ret; > + > + return IIO_VAL_INT; > + > + } else if (mask == IIO_CHAN_INFO_SCALE) { > + *val = 5000; /* on board vref millivolts */ > + *val2 = 25; /* 25 (24 + sign) data bits */ > + return IIO_VAL_FRACTIONAL_LOG2; > + > + } else { > + return -EINVAL; > + } > +} > + > +static const struct iio_chan_spec ltc2485_channel[] = { > + { > + .type = IIO_VOLTAGE, > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) > + }, > +}; > + > +static const struct iio_info ltc2485_info = { > + .read_raw = ltc2485_read_raw, > + .driver_module = THIS_MODULE, > +}; > + > +static int ltc2485_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct iio_dev *indio_dev; > + struct ltc2485_data *data; > + int ret; > + > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | > + I2C_FUNC_SMBUS_WRITE_BYTE)) > + return -EOPNOTSUPP; > + > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); > + if (!indio_dev) > + return -ENOMEM; > + > + data = iio_priv(indio_dev); > + i2c_set_clientdata(client, indio_dev); > + data->client = client; > + > + indio_dev->dev.parent = &client->dev; > + indio_dev->name = id->name; > + indio_dev->info = <c2485_info; > + indio_dev->modes = INDIO_DIRECT_MODE; > + indio_dev->channels = ltc2485_channel; > + indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel); > + > + ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT); > + if (ret < 0) > + return ret; > + > + data->time_prev = ktime_get_real_ns(); > + return devm_iio_device_register(&client->dev, indio_dev); > +} > + > +static const struct i2c_device_id ltc2485_id[] = { > + { "ltc2485", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, ltc2485_id); > + > +static struct i2c_driver ltc2485_driver = { > + .driver = { > + .name = "ltc2485", > + }, > + .probe = ltc2485_probe, > + .id_table = ltc2485_id, > +}; > +module_i2c_driver(ltc2485_driver); > + > +MODULE_AUTHOR("Alison Schofield <[email protected]>"); > +MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver"); > +MODULE_LICENSE("GPL v2"); > -- Peter Meerwald-Stadler +43-664-2444418 (mobile)
