On Sun, 2 Jul 2017 10:29:35 +0200 (CEST) Peter Meerwald-Stadler <pme...@pmeerw.net> wrote:
> > The LTC2741 and LTC2473 are single voltage ADC chips. The LTC2473 > > is similar to the LTC2471 but outputs a signed differential value. > > comments below > > > Datasheet: > > http://cds.linear.com/docs/en/datasheet/24713fb.pdf > > > > Signed-off-by: Mike Looijmans <mike.looijm...@topic.nl> Enough here that I've dropped the patch for now and look forward to a v2 incorporating both Peter and Lars' comments. Jonathan > > --- > > Note: Moved from "hwmon" subsystem to "iio" as discussed per e-mail, > > see also: https://patchwork.kernel.org/patch/9816607/ > > Only tested the LTC2741 in real life. > > > > drivers/iio/adc/Kconfig | 10 +++ > > drivers/iio/adc/Makefile | 1 + > > drivers/iio/adc/ltc2471.c | 163 > > ++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 174 insertions(+) > > create mode 100644 drivers/iio/adc/ltc2471.c > > > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > > index 401f47b..fbee44a 100644 > > --- a/drivers/iio/adc/Kconfig > > +++ b/drivers/iio/adc/Kconfig > > @@ -362,6 +362,16 @@ config LPC32XX_ADC > > activate only one via device tree selection. Provides direct access > > via sysfs. > > > > +config LTC2471 > > + tristate "Linear Technology LTC2471 and LTC2473 ADC driver" > > + depends on I2C > > + help > > + Say yes here to build support for Linear Technology LTC2471 and > > + LTC2473 ADC. > > + > > + This driver can also be built as a module. If so, the module will > > + be called ltc2471. > > + > > config LTC2485 > > tristate "Linear Technology LTC2485 ADC driver" > > depends on I2C > > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile > > index 9339bec..afafe85 100644 > > --- a/drivers/iio/adc/Makefile > > +++ b/drivers/iio/adc/Makefile > > @@ -34,6 +34,7 @@ obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o > > obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o > > obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o > > obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o > > +obj-$(CONFIG_LTC2471) += ltc2471.o > > obj-$(CONFIG_LTC2485) += ltc2485.o > > obj-$(CONFIG_LTC2497) += ltc2497.o > > obj-$(CONFIG_MAX1027) += max1027.o > > diff --git a/drivers/iio/adc/ltc2471.c b/drivers/iio/adc/ltc2471.c > > new file mode 100644 > > index 0000000..f26bdad > > --- /dev/null > > +++ b/drivers/iio/adc/ltc2471.c > > @@ -0,0 +1,163 @@ > > +/* > > + * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors > > + * The LTC2473 is identical to the 2471, but reports a differential signal. > > + * > > + * Copyright (C) 2017 Topic Embedded Products > > + * Author: Mike Looijmans <mike.looijm...@topic.nl> > > + * > > + * License: GPLv2 > > + */ > > + > > +#include <linux/err.h> > > +#include <linux/i2c.h> > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > +#include <linux/iio/iio.h> > > +#include <linux/iio/sysfs.h> > > + > > +enum chips { > > ltc2471_ prefix please > > > + ltc2471, > > + ltc2473 > > end last line with a comma, so additions can be done with a one-line patch > > > +}; > > + > > +struct ltc2471_data { > > + struct i2c_client *client; > > +}; > > + > > +/* Reference voltage is 1.25V */ > > +#define LTC2471_VREF 1250 > > + > > +/* Read two bytes from the I2C bus to obtain the ADC result */ > > +static int ltc2471_get_value(struct i2c_client *client) > > +{ > > + int ret; > > + __be16 buf; > > + > > + ret = i2c_master_recv(client, (char *)&buf, 2); > > sizeof(buf) probably > > > + if (ret < 0) > > + return ret; > > + if (ret != 2) > > sizeof(buf) probably > > > + return -EIO; > > + > > + /* MSB first */ > > + return be16_to_cpu(buf); > > +} > > + > > +static int ltc2471_read_raw(struct iio_dev *indio_dev, > > + struct iio_chan_spec const *chan, > > + int *val, int *val2, long info) > > +{ > > + struct ltc2471_data *data = iio_priv(indio_dev); > > + int ret; > > + > > + switch (info) { > > + case IIO_CHAN_INFO_RAW: > > + ret = ltc2471_get_value(data->client); > > + if (ret < 0) > > + return ret; > > + *val = ret; > > + return IIO_VAL_INT; > > + > > + case IIO_CHAN_INFO_SCALE: > > + if (chan->differential) > > + /* Output ranges from -VREF to +VREF */ > > + *val = 2 * LTC2471_VREF; > > + else > > + /* Output ranges from 0 to VREF */ > > + *val = LTC2471_VREF; > > + *val2 = 16; /* 16 data bits */ > > + return IIO_VAL_FRACTIONAL_LOG2; > > + > > + case IIO_CHAN_INFO_OFFSET: > > + if (chan->differential) > > + *val = -LTC2471_VREF; > > + else > > + *val = 0; > > the non-differential (single ended) chip has no offset channel anyway > according to iio_chan_spec... > > > + return IIO_VAL_INT; > > + > > + default: > > + return -EINVAL; > > + } > > +} > > + > > +static const struct iio_chan_spec ltc2471_channel[] = { > > + { > > + .type = IIO_VOLTAGE, > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > > + .differential = 0, > > .differential = 0 not needed > > > + }, > > +}; > > +static const struct iio_chan_spec ltc2473_channel[] = { > > + { > > + .type = IIO_VOLTAGE, > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | > > + BIT(IIO_CHAN_INFO_OFFSET), > > + .differential = 1, > > + }, > > +}; > > + > > +static const struct iio_info ltc2471_info = { > > + .read_raw = ltc2471_read_raw, > > + .driver_module = THIS_MODULE, > > +}; > > + > > +static int ltc2471_i2c_probe(struct i2c_client *client, > > + const struct i2c_device_id *id) > > +{ > > + struct iio_dev *indio_dev; > > + struct ltc2471_data *data; > > + int ret; > > + > > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) > > + 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 = <c2471_info; > > + indio_dev->modes = INDIO_DIRECT_MODE; > > + if (id->driver_data == ltc2473) > > + indio_dev->channels = ltc2473_channel; > > + else > > + indio_dev->channels = ltc2471_channel; > > + indio_dev->num_channels = 1; > > + > > + /* Trigger once to start conversion and check if chip is there */ > > + ret = ltc2471_get_value(client); > > + if (ret < 0) { > > + dev_err(&client->dev, "Cannot read from device.\n"); > > + return ret; > > + } > > + > > + return devm_iio_device_register(&client->dev, indio_dev); > > +} > > + > > +static const struct i2c_device_id ltc2471_i2c_id[] = { > > + { "ltc2471", ltc2471 }, > > + { "ltc2473", ltc2473 }, > > + {} > > +}; > > +MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id); > > + > > +static struct i2c_driver ltc2471_i2c_driver = { > > + .driver = { > > + .name = "ltc2471", > > + }, > > + .probe = ltc2471_i2c_probe, > > + .id_table = ltc2471_i2c_id, > > +}; > > + > > +module_i2c_driver(ltc2471_i2c_driver); > > + > > +MODULE_DESCRIPTION("LTC2471/LTC2473 Sensor Driver"); > > maybe "ADC driver" > > > +MODULE_AUTHOR("Topic Embedded Products"); > > +MODULE_LICENSE("GPL v2"); > > >
