Messages in this thread | | | Date | Thu, 18 Sep 2014 13:55:52 -0500 | From | David Barksdale <> | Subject | Re: [PATCH] IIO: add si701x driver |
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On 09/18/2014 12:43 PM, Peter Meerwald wrote: > >> This patch adds support to the Industrial IO subsystem >> for the Silicon Labs Si701x/2x Relative Humidity and >> Temperature Sensors. > > the name si701x is problematic; the si7015 for example is supported by > the si7005 driver > > how about calling the driver si7020 and stating that it also supports > si7013, si7021 -- the x notation in driver names always leads to touble...
Sounds good.
> the additional features of the si7013 are not supported by the driver > >> Website: http://www.silabs.com/products/sensors/humidity-sensors/Pages/si7013-20-21.aspx >> >> These are i2c devices which measure relative humidity >> and temperature and all use the same protocol. The >> Si7013 has an additional input with programmable >> linearization which is not supported because that's >> complicated and I didn't need it. >> >> Signed-off-by: David Barksdale <dbarksdale@uplogix.com> >> >> --- >> drivers/iio/humidity/Kconfig | 10 +++ >> drivers/iio/humidity/Makefile | 1 + >> drivers/iio/humidity/si701x.c | 159 ++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 170 insertions(+) >> >> diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig >> index e116bd8..ba0ef61 100644 >> --- a/drivers/iio/humidity/Kconfig >> +++ b/drivers/iio/humidity/Kconfig >> @@ -22,4 +22,14 @@ config SI7005 >> To compile this driver as a module, choose M here: the module >> will be called si7005. >> >> +config SI701X >> + tristate "Si701x/2x Relative Humidity and Temperature Sensors" >> + depends on I2C >> + help >> + Say yes here to build support for the Silicon Labs Si701x/2x Relative >> + Humidity and Temperature Sensors. >> + >> + To compile this driver as a module, choose M here: the module >> + will be called si701x. >> + >> endmenu >> diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile >> index e3f3d94..d2e9645 100644 >> --- a/drivers/iio/humidity/Makefile >> +++ b/drivers/iio/humidity/Makefile >> @@ -4,3 +4,4 @@ >> >> obj-$(CONFIG_DHT11) += dht11.o >> obj-$(CONFIG_SI7005) += si7005.o >> +obj-$(CONFIG_SI701X) += si701x.o >> diff --git a/drivers/iio/humidity/si701x.c b/drivers/iio/humidity/si701x.c >> new file mode 100644 >> index 0000000..1a2ee22 >> --- /dev/null >> +++ b/drivers/iio/humidity/si701x.c >> @@ -0,0 +1,159 @@ >> +/* >> + * si701x.c - Silicon Labs Si701x/2x Relative Humidity and Temperature Sensors >> + * Copyright (c) 2013,2014 Uplogix, Inc. >> + * David Barksdale <dbarksdale@uplogix.com> >> + * >> + * This program is free software; you can redistribute it and/or modify it >> + * under the terms and conditions of the GNU General Public License, >> + * version 2, as published by the Free Software Foundation. >> + * >> + * This program is distributed in the hope that it will be useful, >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >> + * GNU General Public License for more details. >> + */ >> + >> +/* >> + * The Silicon Labs Si701x/2x Relative Humidity and Temperature Sensors >> + * are i2c devices which have an identical programming interface for >> + * measuring relative humidity and temperature. The Si7013 has an additional >> + * temperature input which this driver does not support. >> + * >> + * Data Sheets: >> + * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf >> + * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf >> + * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf >> + */ >> + >> +#include <linux/i2c.h> >> +#include <linux/module.h> >> +#include <linux/slab.h> >> +#include <linux/sysfs.h> >> + >> +#include <linux/iio/iio.h> >> +#include <linux/iio/sysfs.h> >> + >> +enum { >> + /* Measure Relative Humidity, Hold Master Mode */ >> + SI701XCMD_RH_HOLD = 0xE5, >> + /* Measure Temperature, Hold Master Mode */ >> + SI701XCMD_TEMP_HOLD = 0xE3, >> +}; >> + >> +struct si701x_data { >> + struct i2c_client *client; >> + struct mutex lock; >> +}; >> + >> +static int si701x_read_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, int *val, >> + int *val2, long mask) >> +{ >> + struct si701x_data *data = iio_priv(indio_dev); >> + int ret; >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_RAW: >> + mutex_lock(&data->lock); > > is the locking needed? what is protected?
I copied this from the si7005 driver. I assumed because calls to read_raw were not serialized and calls to i2c_smbus_read_word_data on the same client need to be serialized.
>> + ret = i2c_smbus_read_word_data(data->client, >> + chan->type == IIO_TEMP ? >> + SI701XCMD_TEMP_HOLD : >> + SI701XCMD_RH_HOLD); >> + mutex_unlock(&data->lock); >> + if (ret < 0) >> + return ret; >> + *val = ret; >> + return IIO_VAL_INT; >> + case IIO_CHAN_INFO_SCALE: >> + if (chan->type == IIO_TEMP) { >> + *val = 175.72 * 1000; > > floating-point constants in kernel space makes me nervous >
I was trying to make this easy to compare to constants that appear in the data sheets: 175.72, 125, 65536, -6, and -46.85. I figured the compiler would transform them to integers, but I suppose that's not a great assumption. I'll precompute them and explain them in a comment.
>> + *val2 = 65536; > > could set val2 once after the if > >> + } else { >> + *val = 125 * 1000; >> + *val2 = 65536; >> + } >> + return IIO_VAL_FRACTIONAL; >> + case IIO_CHAN_INFO_OFFSET: >> + if (chan->type == IIO_TEMP) >> + *val = -46.85 * 65536 / 175.72; >> + else >> + *val = -6 * 65536 / 125; >> + return IIO_VAL_INT; >> + default: >> + break; >> + } >> + >> + return -EINVAL; >> +} >> + >> +static const struct iio_chan_spec si701x_channels[] = { >> + { >> + .type = IIO_HUMIDITYRELATIVE, >> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | >> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), >> + }, >> + { >> + .type = IIO_TEMP, >> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | >> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), >> + } >> +}; >> + >> +static const struct iio_info si701x_info = { >> + .read_raw = si701x_read_raw, >> + .driver_module = THIS_MODULE, >> +}; >> + >> +static int si701x_probe(struct i2c_client *client, >> + const struct i2c_device_id *id) >> +{ >> + struct iio_dev *dev; >> + struct si701x_data *data; >> + >> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA)) >> + return -ENODEV; >> + >> + dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); >> + if (!dev) >> + return -ENOMEM; >> + >> + data = iio_priv(dev); >> + i2c_set_clientdata(client, dev); >> + data->client = client; >> + mutex_init(&data->lock); >> + >> + dev->dev.parent = &client->dev; >> + dev->name = dev_name(&client->dev); >> + dev->modes = INDIO_DIRECT_MODE; >> + dev->info = &si701x_info; >> + dev->channels = si701x_channels; >> + dev->num_channels = ARRAY_SIZE(si701x_channels); >> + >> + return devm_iio_device_register(&client->dev, dev); >> +} >> + >> +static const unsigned short si701x_address_list[] = { >> + 0x40, > > the alternate address is 0x41 >
Thanks.
>> + I2C_CLIENT_END >> +}; >> + >> +static const struct i2c_device_id si701x_id[] = { >> + { "si701x", 0 }, >> + { } >> +}; >> +MODULE_DEVICE_TABLE(i2c, si701x_id); >> + >> +static struct i2c_driver si701x_driver = { >> + .class = I2C_CLASS_HWMON, >> + .driver.name = "si701x", >> + .probe = si701x_probe, >> + .address_list = si701x_address_list, >> + .id_table = si701x_id, > > address_list and I2C_CLASS_HWMON -- what for? > > if doing auto-probing, I'd check the chip's ID >
Oops. This was originally an hwmon driver but I ported it to iio when I saw that's where si7005 landed.
>> +}; >> + >> +module_i2c_driver(si701x_driver); >> +MODULE_DESCRIPTION("Silicon Labs Si701x/2x " >> + "Relative Humidity and Temperature Sensors"); >> +MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>"); >> +MODULE_LICENSE("GPL"); >> + >> >
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