On 08/01/17 11:12, Jonathan Cameron wrote:
> On 05/01/17 17:51, Andreas Klinger wrote:
>> This is the IIO driver for AVIA HX711 ADC which is mostly used in weighting
>> cells.
>>
>> The protocol is quite simple and using GPIOs:
>> One GPIO is used as clock (SCK) while another GPIO is read (DOUT)
>>
>> The raw value read from the chip is delivered.
>> To get a weight one needs to subtract the zero offset and scale it.
>>
>> Signed-off-by: Andreas Klinger <ak@xxxxxxxxxxxxx>
> I think your locking is a little heavy handed, perhaps a follow up patch to
> relax it a little.
>
> I fixed a trivial typo when applying.
>
> Applied to the togreg branch of iio.git and pushed out as testing for the
> autobuilders to play with it.
And I forgot to fix the missing mutex_unlock. Good thing zeroday caught that.
Updated and pushed out again for another round of build tests.
Jonathan
>
> Thanks,
>
> Jonathan
>> ---
>> drivers/iio/adc/Kconfig | 19 ++
>> drivers/iio/adc/Makefile | 1 +
>> drivers/iio/adc/hx711.c | 531 +++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 551 insertions(+)
>> create mode 100644 drivers/iio/adc/hx711.c
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 932de1f9d1e7..1dcf2ace1697 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -205,6 +205,25 @@ config HI8435
>> This driver can also be built as a module. If so, the module will be
>> called hi8435.
>>
>> +config HX711
>> + tristate "AVIA HX711 ADC for weight cells"
>> + depends on GPIOLIB
>> + help
>> + If you say yes here you get support for AVIA HX711 ADC which is used
>> + for weigh cells
>> +
>> + This driver uses two GPIOs, one acts as the clock and controls the
>> + channel selection and gain, the other one is used for the measurement
>> + data
>> +
>> + Currently the raw value is read from the chip and delivered.
>> + To get an actual weight one needs to subtract the
>> + zero offset and multiply by a scale factor.
>> + This should be done in userspace.
>> +
>> + This driver can also be built as a module. If so, the module will be
>> + called hx711.
>> +
>> config INA2XX_ADC
>> tristate "Texas Instruments INA2xx Power Monitors IIO driver"
>> depends on I2C && !SENSORS_INA2XX
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index b1aa456e6af3..d46e289900ef 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -21,6 +21,7 @@ obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
>> obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>> obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
>> obj-$(CONFIG_HI8435) += hi8435.o
>> +obj-$(CONFIG_HX711) += hx711.o
>> obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>> obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
>> obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>> diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
>> new file mode 100644
>> index 000000000000..e41414556158
>> --- /dev/null
>> +++ b/drivers/iio/adc/hx711.c
>> @@ -0,0 +1,531 @@
>> +/*
>> + * HX711: analog to digital converter for weight sensor module
>> + *
>> + * Copyright (c) 2016 Andreas Klinger <ak@xxxxxxxxxxxxx>
>> + *
>> + * 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.
>> + *
>> + * 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.
>> + */
>> +#include <linux/err.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/property.h>
>> +#include <linux/slab.h>
>> +#include <linux/sched.h>
>> +#include <linux/delay.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/regulator/consumer.h>
>> +
>> +/* gain to pulse and scale conversion */
>> +#define HX711_GAIN_MAX 3
>> +
>> +struct hx711_gain_to_scale {
>> + int gain;
>> + int gain_pulse;
>> + int scale;
>> + int channel;
>> +};
>> +
>> +/*
>> + * .scale depends on AVDD which in turn is known as soon as the regulator
>> + * is available
>> + * therefore we set .scale in hx711_probe()
>> + *
>> + * channel A in documentation is channel 0 in source code
>> + * channel B in documentation is channel 1 in source code
>> + */
>> +static struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = {
>> + { 128, 1, 0, 0 },
>> + { 32, 2, 0, 1 },
>> + { 64, 3, 0, 0 }
>> +};
>> +
>> +static int hx711_get_gain_to_pulse(int gain)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < HX711_GAIN_MAX; i++)
>> + if (hx711_gain_to_scale[i].gain == gain)
>> + return hx711_gain_to_scale[i].gain_pulse;
>> + return 1;
>> +}
>> +
>> +static int hx711_get_gain_to_scale(int gain)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < HX711_GAIN_MAX; i++)
>> + if (hx711_gain_to_scale[i].gain == gain)
>> + return hx711_gain_to_scale[i].scale;
>> + return 0;
>> +}
>> +
>> +static int hx711_get_scale_to_gain(int scale)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < HX711_GAIN_MAX; i++)
>> + if (hx711_gain_to_scale[i].scale == scale)
>> + return hx711_gain_to_scale[i].gain;
>> + return -EINVAL;
>> +}
>> +
>> +struct hx711_data {
>> + struct device *dev;
>> + struct gpio_desc *gpiod_pd_sck;
>> + struct gpio_desc *gpiod_dout;
>> + struct regulator *reg_avdd;
>> + int gain_set; /* gain set on device */
>> + int gain_chan_a; /* gain for channel A */
>> + struct mutex lock;
>> +};
>> +
>> +static int hx711_cycle(struct hx711_data *hx711_data)
>> +{
>> + int val;
>> +
>> + /*
>> + * if preempted for more then 60us while PD_SCK is high:
>> + * hx711 is going in reset
>> + * ==> measuring is false
>> + */
>> + preempt_disable();
>> + gpiod_set_value(hx711_data->gpiod_pd_sck, 1);
>> + val = gpiod_get_value(hx711_data->gpiod_dout);
>> + /*
>> + * here we are not waiting for 0.2 us as suggested by the datasheet,
>> + * because the oszilloscope showed in a test scenario
>> + * at least 1.15 us for PD_SCK high (T3 in datasheet)
>> + * and 0.56 us for PD_SCK low on TI Sitara with 800 MHz
>> + */
>> + gpiod_set_value(hx711_data->gpiod_pd_sck, 0);
>> + preempt_enable();
>> +
>> + return val;
>> +}
>> +
>> +static int hx711_read(struct hx711_data *hx711_data)
>> +{
>> + int i, ret;
>> + int value = 0;
>> + int val = gpiod_get_value(hx711_data->gpiod_dout);
>> +
>> + /* we double check if it's really down */
>> + if (val)
>> + return -EIO;
>> +
>> + for (i = 0; i < 24; i++) {
>> + value <<= 1;
>> + ret = hx711_cycle(hx711_data);
>> + if (ret)
>> + value++;
>> + }
>> +
>> + value ^= 0x800000;
>> +
>> + for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++)
>> + hx711_cycle(hx711_data);
>> +
>> + return value;
>> +}
>> +
>> +static int hx711_wait_for_ready(struct hx711_data *hx711_data)
>> +{
>> + int i, val;
>> +
>> + /*
>> + * a maximum reset cycle time of 56 ms was measured.
>> + * we round it up to 100 ms
>> + */
>> + for (i = 0; i < 100; i++) {
>> + val = gpiod_get_value(hx711_data->gpiod_dout);
>> + if (!val)
>> + break;
>> + /* sleep at least 1 ms */
>> + msleep(1);
>> + }
>> + if (val)
>> + return -EIO;
>> +
>> + return 0;
>> +}
>> +
>> +static int hx711_reset(struct hx711_data *hx711_data)
>> +{
>> + int ret;
>> + int val = gpiod_get_value(hx711_data->gpiod_dout);
>> +
>> + if (val) {
>> + /*
>> + * an examination with the oszilloscope indicated
> oscilloscope
>> + * that the first value read after the reset is not stable
>> + * if we reset too short;
>> + * the shorter the reset cycle
>> + * the less reliable the first value after reset is;
>> + * there were no problems encountered with a value
>> + * of 10 ms or higher
>> + */
>> + gpiod_set_value(hx711_data->gpiod_pd_sck, 1);
>> + msleep(10);
>> + gpiod_set_value(hx711_data->gpiod_pd_sck, 0);
>> +
>> + ret = hx711_wait_for_ready(hx711_data);
>> + if (ret)
>> + return ret;
>> + /*
>> + * after a reset the gain is 128 so we do a dummy read
>> + * to set the gain for the next read
>> + */
>> + ret = hx711_read(hx711_data);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /*
>> + * after a dummy read we need to wait vor readiness
>> + * for not mixing gain pulses with the clock
>> + */
>> + ret = hx711_wait_for_ready(hx711_data);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + return val;
>> +}
>> +
>> +static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
>> +{
>> + int ret;
>> +
>> + if (chan == 0) {
>> + if (hx711_data->gain_set == 32) {
>> + hx711_data->gain_set = hx711_data->gain_chan_a;
>> +
>> + ret = hx711_read(hx711_data);
>> + if (ret < 0)
>> + return ret;
>> +
>> + ret = hx711_wait_for_ready(hx711_data);
>> + if (ret)
>> + return ret;
>> + }
>> + } else {
>> + if (hx711_data->gain_set != 32) {
>> + hx711_data->gain_set = 32;
>> +
>> + ret = hx711_read(hx711_data);
>> + if (ret < 0)
>> + return ret;
>> +
>> + ret = hx711_wait_for_ready(hx711_data);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int hx711_read_raw(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan,
>> + int *val, int *val2, long mask)
>> +{
>> + struct hx711_data *hx711_data = iio_priv(indio_dev);
>> + int ret;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_RAW:
>> + mutex_lock(&hx711_data->lock);
>> +
>> + /*
>> + * hx711_reset() must be called from here
>> + * because it could be calling hx711_read() by itself
>> + */
>> + if (hx711_reset(hx711_data)) {
> No unlock in this error path.
>> + dev_err(hx711_data->dev, "reset failed!");
>> + return -EIO;
>> + }
>> +
>> + ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
>> + if (ret < 0) {
>> + mutex_unlock(&hx711_data->lock);
>> + return ret;
>> + }
>> +
>> + *val = hx711_read(hx711_data);
>> +
>> + mutex_unlock(&hx711_data->lock);
>> +
>> + if (*val < 0)
>> + return *val;
>> + return IIO_VAL_INT;
>> + case IIO_CHAN_INFO_SCALE:
>> + *val = 0;
>> + mutex_lock(&hx711_data->lock);
>> +
> Looking feels overly paranoid here as we are only accessing locally stored
> data. Still it's not actively doing any harm...
>> + *val2 = hx711_get_gain_to_scale(hx711_data->gain_set);
>> +
>> + mutex_unlock(&hx711_data->lock);
>> +
>> + return IIO_VAL_INT_PLUS_NANO;
>> + default:
>> + return -EINVAL;
>> + }
>> +}
>> +
>> +static int hx711_write_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int val,
>> + int val2,
>> + long mask)
>> +{
>> + struct hx711_data *hx711_data = iio_priv(indio_dev);
>> + int ret;
>> + int gain;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_SCALE:
>> + /*
>> + * a scale greater than 1 mV per LSB is not possible
>> + * with the HX711, therefore val must be 0
>> + */
>> + if (val != 0)
>> + return -EINVAL;
>> +
>> + mutex_lock(&hx711_data->lock);
>> +
>> + gain = hx711_get_scale_to_gain(val2);
>> + if (gain < 0) {
>> + mutex_unlock(&hx711_data->lock);
>> + return gain;
>> + }
>> +
>> + if (gain != hx711_data->gain_set) {
>> + hx711_data->gain_set = gain;
>> + if (gain != 32)
>> + hx711_data->gain_chan_a = gain;
>> +
>> + ret = hx711_read(hx711_data);
>> + if (ret < 0) {
>> + mutex_unlock(&hx711_data->lock);
>> + return ret;
>> + }
>> + }
>> +
>> + mutex_unlock(&hx711_data->lock);
>> + return 0;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + long mask)
>> +{
>> + return IIO_VAL_INT_PLUS_NANO;
>> +}
>> +
>> +static ssize_t hx711_scale_available_show(struct device *dev,
>> + struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);
>> + int channel = iio_attr->address;
>> + int i, len = 0;
>> +
>> + for (i = 0; i < HX711_GAIN_MAX; i++)
>> + if (hx711_gain_to_scale[i].channel == channel)
>> + len += sprintf(buf + len, "0.%09d ",
>> + hx711_gain_to_scale[i].scale);
>> +
>> + len += sprintf(buf + len, "\n");
>> +
>> + return len;
>> +}
>> +
>> +static IIO_DEVICE_ATTR(in_voltage0_scale_available, S_IRUGO,
>> + hx711_scale_available_show, NULL, 0);
>> +
>> +static IIO_DEVICE_ATTR(in_voltage1_scale_available, S_IRUGO,
>> + hx711_scale_available_show, NULL, 1);
>> +
>> +static struct attribute *hx711_attributes[] = {
>> + &iio_dev_attr_in_voltage0_scale_available.dev_attr.attr,
>> + &iio_dev_attr_in_voltage1_scale_available.dev_attr.attr,
>> + NULL,
>> +};
>> +
>> +static struct attribute_group hx711_attribute_group = {
>> + .attrs = hx711_attributes,
>> +};
>> +
>> +static const struct iio_info hx711_iio_info = {
>> + .driver_module = THIS_MODULE,
>> + .read_raw = hx711_read_raw,
>> + .write_raw = hx711_write_raw,
>> + .write_raw_get_fmt = hx711_write_raw_get_fmt,
>> + .attrs = &hx711_attribute_group,
>> +};
>> +
>> +static const struct iio_chan_spec hx711_chan_spec[] = {
>> + {
>> + .type = IIO_VOLTAGE,
>> + .channel = 0,
>> + .indexed = 1,
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
>> + },
>> + {
>> + .type = IIO_VOLTAGE,
>> + .channel = 1,
>> + .indexed = 1,
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
>> + },
>> +};
>> +
>> +static int hx711_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct hx711_data *hx711_data;
>> + struct iio_dev *indio_dev;
>> + int ret;
>> + int i;
>> +
>> + indio_dev = devm_iio_device_alloc(dev, sizeof(struct hx711_data));
>> + if (!indio_dev) {
>> + dev_err(dev, "failed to allocate IIO device\n");
>> + return -ENOMEM;
>> + }
>> +
>> + hx711_data = iio_priv(indio_dev);
>> + hx711_data->dev = dev;
>> +
>> + mutex_init(&hx711_data->lock);
>> +
>> + /*
>> + * PD_SCK stands for power down and serial clock input of HX711
>> + * in the driver it is an output
>> + */
>> + hx711_data->gpiod_pd_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
>> + if (IS_ERR(hx711_data->gpiod_pd_sck)) {
>> + dev_err(dev, "failed to get sck-gpiod: err=%ld\n",
>> + PTR_ERR(hx711_data->gpiod_pd_sck));
>> + return PTR_ERR(hx711_data->gpiod_pd_sck);
>> + }
>> +
>> + /*
>> + * DOUT stands for serial data output of HX711
>> + * for the driver it is an input
>> + */
>> + hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_IN);
>> + if (IS_ERR(hx711_data->gpiod_dout)) {
>> + dev_err(dev, "failed to get dout-gpiod: err=%ld\n",
>> + PTR_ERR(hx711_data->gpiod_dout));
>> + return PTR_ERR(hx711_data->gpiod_dout);
>> + }
>> +
>> + hx711_data->reg_avdd = devm_regulator_get(dev, "avdd");
>> + if (IS_ERR(hx711_data->reg_avdd))
>> + return PTR_ERR(hx711_data->reg_avdd);
>> +
>> + ret = regulator_enable(hx711_data->reg_avdd);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /*
>> + * with
>> + * full scale differential input range: AVDD / GAIN
>> + * full scale output data: 2^24
>> + * we can say:
>> + * AVDD / GAIN = 2^24
>> + * therefore:
>> + * 1 LSB = AVDD / GAIN / 2^24
>> + * AVDD is in uV, but we need 10^-9 mV
>> + * approximately to fit into a 32 bit number:
>> + * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]
>> + */
>> + ret = regulator_get_voltage(hx711_data->reg_avdd);
>> + if (ret < 0) {
>> + regulator_disable(hx711_data->reg_avdd);
>> + return ret;
>> + }
>> + /* we need 10^-9 mV */
>> + ret *= 100;
>> +
>> + for (i = 0; i < HX711_GAIN_MAX; i++)
>> + hx711_gain_to_scale[i].scale =
>> + ret / hx711_gain_to_scale[i].gain / 1678;
>> +
>> + hx711_data->gain_set = 128;
>> + hx711_data->gain_chan_a = 128;
>> +
>> + platform_set_drvdata(pdev, indio_dev);
>> +
>> + indio_dev->name = "hx711";
>> + indio_dev->dev.parent = &pdev->dev;
>> + indio_dev->info = &hx711_iio_info;
>> + indio_dev->modes = INDIO_DIRECT_MODE;
>> + indio_dev->channels = hx711_chan_spec;
>> + indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
>> +
>> + ret = iio_device_register(indio_dev);
>> + if (ret < 0) {
>> + dev_err(dev, "Couldn't register the device\n");
>> + regulator_disable(hx711_data->reg_avdd);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static int hx711_remove(struct platform_device *pdev)
>> +{
>> + struct hx711_data *hx711_data;
>> + struct iio_dev *indio_dev;
>> +
>> + indio_dev = platform_get_drvdata(pdev);
>> + hx711_data = iio_priv(indio_dev);
>> +
>> + iio_device_unregister(indio_dev);
>> +
>> + regulator_disable(hx711_data->reg_avdd);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id of_hx711_match[] = {
>> + { .compatible = "avia,hx711", },
>> + {},
>> +};
>> +
>> +MODULE_DEVICE_TABLE(of, of_hx711_match);
>> +
>> +static struct platform_driver hx711_driver = {
>> + .probe = hx711_probe,
>> + .remove = hx711_remove,
>> + .driver = {
>> + .name = "hx711-gpio",
>> + .of_match_table = of_hx711_match,
>> + },
>> +};
>> +
>> +module_platform_driver(hx711_driver);
>> +
>> +MODULE_AUTHOR("Andreas Klinger <ak@xxxxxxxxxxxxx>");
>> +MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:hx711-gpio");
>> +
>>
>
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