> This is the IIO driver for AVIA HX711 ADC which ist mostly used in weighting > cells. comments below > The protocol is quite simple and using GPIO's: GPIOs > One GPIO is used as clock (SCK) while another GPIO is read (DOUT) > > Signed-off-by: Andreas Klinger <ak@xxxxxxxxxxxxx> > --- > drivers/iio/adc/Kconfig | 13 +++ > drivers/iio/adc/Makefile | 1 + > drivers/iio/adc/hx711.c | 269 +++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 283 insertions(+) > create mode 100644 drivers/iio/adc/hx711.c > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index 932de1f9d1e7..7902b50fcf32 100644 > --- a/drivers/iio/adc/Kconfig > +++ b/drivers/iio/adc/Kconfig > @@ -205,6 +205,19 @@ 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 weight cells > + > + This driver uses two GPIO's, one for setting the clock and the other GPIOs > + one for getting the data > + > + 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..cbc89e467985 > --- /dev/null > +++ b/drivers/iio/adc/hx711.c > @@ -0,0 +1,269 @@ > +/* > + * HX711: analog to digital converter for weight sensor module > + * > + * Copyright (c) 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/gpio.h> > +#include <linux/gpio/consumer.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> > + > +#define HX711_GAIN_32 2 /* gain = 32 for channel B */ > +#define HX711_GAIN_64 3 /* gain = 64 for channel A */ > +#define HX711_GAIN_128 1 /* gain = 128 for channel A */ > + only one newline here please > + > +struct hx711_data { > + struct device *dev; > + dev_t devt; devt is not used, delete > + struct gpio_desc *gpiod_sck; > + struct gpio_desc *gpiod_dout; > + int gain_pulse; > + struct mutex lock; > +}; > + > +static void hx711_reset(struct hx711_data *hx711_data) > +{ > + int val; > + int i; > + > + val = gpiod_get_value(hx711_data->gpiod_dout); > + if (val) { > + dev_warn(hx711_data->dev, "RESET-HX711\n"); message needed? > + > + gpiod_set_value(hx711_data->gpiod_sck, 1); > + udelay(80); > + gpiod_set_value(hx711_data->gpiod_sck, 0); > + > + for (i = 0; i < 1000; i++) { > + val = gpiod_get_value(hx711_data->gpiod_dout); > + if (!val) > + break; > + /* sleep at least 1 ms*/ add space before */ > + msleep(1); > + } can this fail? what is it takes longer than 1000 * 1ms? > + } > +} > + > +static int hx711_cycle(struct hx711_data *hx711_data) > +{ > + int val; > + > + /* if preempted for more then 60us while SCK is high: > + * hx711 is going in reset > + * ==> measuring is false > + */ > + preempt_disable(); > + gpiod_set_value(hx711_data->gpiod_sck, 1); > + val = gpiod_get_value(hx711_data->gpiod_dout); > + gpiod_set_value(hx711_data->gpiod_sck, 0); > + preempt_enable(); > + > + return val; > +} > + > +static unsigned int hx711_read(struct hx711_data *hx711_data) > +{ > + int i; > + int ret; > + int wert = 0; val or value maybe? should be unsigned int to match the return type of the function > + > + hx711_reset(hx711_data); > + > + for (i = 0; i < 24; i++) { > + wert <<= 1; > + ret = hx711_cycle(hx711_data); > + if (ret) > + wert++; > + } > + > + wert ^= 0x800000; > + > + for (i = 0; i < hx711_data->gain_pulse; i++) > + ret = hx711_cycle(hx711_data); > + > + return wert; > +} > + delete newline > + > +static int hx711_read_raw(struct iio_dev *iio_dev, > + const struct iio_chan_spec *chan, > + int *val, int *val2, long mask) > +{ > + struct hx711_data *hx711_data = iio_priv(iio_dev); > + int ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + switch (chan->type) { > + case IIO_VOLTAGE: > + mutex_lock(&hx711_data->lock); > + *val = (int)hx711_read(hx711_data); > + mutex_unlock(&hx711_data->lock); > + ret = IIO_VAL_INT; return IIO_VAL_INT; > + break; > + default: > + return -EINVAL; > + } > + return ret; > + default: > + return -EINVAL; > + } > + > + return ret; delete, dead code > +} > + > +static const struct iio_info hx711_iio_info = { > + .driver_module = THIS_MODULE, > + .read_raw = hx711_read_raw, > +}; > + > +static const struct iio_chan_spec hx711_chan_spec[] = { > + { .type = IIO_VOLTAGE, > + .channel = 0, .channel = 0 not needed, there is only one channel > + .info_mask_separate = > + BIT(IIO_CHAN_INFO_RAW), > + .scan_type = { scan_type not needed, driver does not support buffered reads > + .sign = 'u', > + .realbits = 24, > + .storagebits = 32, > + .shift = 0, > + } > + }, > +}; > + > +static int hx711_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct device_node *node = dev->of_node; > + struct hx711_data *hx711_data = NULL; > + struct iio_dev *iio; > + int ret = 0, ival; > + > + iio = devm_iio_device_alloc(dev, sizeof(struct hx711_data)); > + if (!iio) { > + dev_err(dev, "failed to allocate IIO device\n"); > + return -ENOMEM; > + } > + > + hx711_data = iio_priv(iio); > + hx711_data->dev = dev; > + > + mutex_init(&hx711_data->lock); > + > + hx711_data->gpiod_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_HIGH); > + if (IS_ERR(hx711_data->gpiod_sck)) { > + ret = PTR_ERR(hx711_data->gpiod_sck); > + goto err; > + } > + > + hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_OUT_HIGH); > + if (IS_ERR(hx711_data->gpiod_dout)) { > + ret = PTR_ERR(hx711_data->gpiod_dout); > + goto err; > + } > + > + ret = of_property_read_u32 (node, "gain", &ival); > + if (!ret) { > + switch (ival) { > + case 32: > + hx711_data->gain_pulse = HX711_GAIN_32; > + break; > + case 64: > + hx711_data->gain_pulse = HX711_GAIN_64; > + break; > + case 128: merge default and case 128? > + hx711_data->gain_pulse = HX711_GAIN_128; > + break; > + default: > + hx711_data->gain_pulse = HX711_GAIN_128; > + } > + } else > + hx711_data->gain_pulse = HX711_GAIN_128; > + dev_dbg(hx711_data->dev, "gain: %d\n", hx711_data->gain_pulse); > + > + ret = gpiod_direction_input(hx711_data->gpiod_dout); > + if (ret < 0) { > + dev_err(hx711_data->dev, "gpiod_direction_input: %d\n", ret); > + goto err; > + } > + > + ret = gpiod_direction_output(hx711_data->gpiod_sck, 0); > + if (ret < 0) { > + dev_err(hx711_data->dev, "gpiod_direction_output: %d\n", ret); > + goto err; > + } > + > + platform_set_drvdata(pdev, iio); > + > + iio->name = pdev->name; > + iio->dev.parent = &pdev->dev; > + iio->info = &hx711_iio_info; > + iio->modes = INDIO_DIRECT_MODE; > + iio->channels = hx711_chan_spec; > + iio->num_channels = ARRAY_SIZE(hx711_chan_spec); > + > + dev_err(hx711_data->dev, "initialized\n"); excessive logging, please remove > + > + return devm_iio_device_register(dev, iio); > + > +err: > + return ret; just return directly without goto? > +} > + > + > +static int hx711_suspend(struct device *dev) > +{ pointless, just don't do PM support > + return 0; > +} > + > +static int hx711_resume(struct device *dev) > +{ > + return 0; > +} > + > +static SIMPLE_DEV_PM_OPS(hx711_pm_ops, hx711_suspend, hx711_resume); > + > + > +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, > + .driver = { > + .name = "hx711-gpio", > + .pm = &hx711_pm_ops, > + .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"); > + > -- Peter Meerwald-Stadler +43-664-2444418 (mobile) -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html