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 <[email protected]> > 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 <[email protected]> >> + * >> + * 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 <[email protected]>"); >> +MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells"); >> +MODULE_LICENSE("GPL"); >> +MODULE_ALIAS("platform:hx711-gpio"); >> + >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html >
