1c3b2fdd0SAndreas Klinger /* 2c3b2fdd0SAndreas Klinger * HX711: analog to digital converter for weight sensor module 3c3b2fdd0SAndreas Klinger * 4c3b2fdd0SAndreas Klinger * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de> 5c3b2fdd0SAndreas Klinger * 6c3b2fdd0SAndreas Klinger * This program is free software; you can redistribute it and/or modify 7c3b2fdd0SAndreas Klinger * it under the terms of the GNU General Public License as published by 8c3b2fdd0SAndreas Klinger * the Free Software Foundation; either version 2 of the License, or 9c3b2fdd0SAndreas Klinger * (at your option) any later version. 10c3b2fdd0SAndreas Klinger * 11c3b2fdd0SAndreas Klinger * This program is distributed in the hope that it will be useful, 12c3b2fdd0SAndreas Klinger * but WITHOUT ANY WARRANTY; without even the implied warranty of 13c3b2fdd0SAndreas Klinger * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14c3b2fdd0SAndreas Klinger * GNU General Public License for more details. 15c3b2fdd0SAndreas Klinger */ 16c3b2fdd0SAndreas Klinger #include <linux/err.h> 17c3b2fdd0SAndreas Klinger #include <linux/kernel.h> 18c3b2fdd0SAndreas Klinger #include <linux/module.h> 19c3b2fdd0SAndreas Klinger #include <linux/of.h> 20c3b2fdd0SAndreas Klinger #include <linux/platform_device.h> 21c3b2fdd0SAndreas Klinger #include <linux/property.h> 22c3b2fdd0SAndreas Klinger #include <linux/slab.h> 23c3b2fdd0SAndreas Klinger #include <linux/sched.h> 24c3b2fdd0SAndreas Klinger #include <linux/delay.h> 25c3b2fdd0SAndreas Klinger #include <linux/iio/iio.h> 26c3b2fdd0SAndreas Klinger #include <linux/iio/sysfs.h> 27c3b2fdd0SAndreas Klinger #include <linux/gpio/consumer.h> 28c3b2fdd0SAndreas Klinger #include <linux/regulator/consumer.h> 29c3b2fdd0SAndreas Klinger 30c3b2fdd0SAndreas Klinger /* gain to pulse and scale conversion */ 31c3b2fdd0SAndreas Klinger #define HX711_GAIN_MAX 3 32c3b2fdd0SAndreas Klinger 33c3b2fdd0SAndreas Klinger struct hx711_gain_to_scale { 34c3b2fdd0SAndreas Klinger int gain; 35c3b2fdd0SAndreas Klinger int gain_pulse; 36c3b2fdd0SAndreas Klinger int scale; 37c3b2fdd0SAndreas Klinger int channel; 38c3b2fdd0SAndreas Klinger }; 39c3b2fdd0SAndreas Klinger 40c3b2fdd0SAndreas Klinger /* 41c3b2fdd0SAndreas Klinger * .scale depends on AVDD which in turn is known as soon as the regulator 42c3b2fdd0SAndreas Klinger * is available 43c3b2fdd0SAndreas Klinger * therefore we set .scale in hx711_probe() 44c3b2fdd0SAndreas Klinger * 45c3b2fdd0SAndreas Klinger * channel A in documentation is channel 0 in source code 46c3b2fdd0SAndreas Klinger * channel B in documentation is channel 1 in source code 47c3b2fdd0SAndreas Klinger */ 48c3b2fdd0SAndreas Klinger static struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = { 49c3b2fdd0SAndreas Klinger { 128, 1, 0, 0 }, 50c3b2fdd0SAndreas Klinger { 32, 2, 0, 1 }, 51c3b2fdd0SAndreas Klinger { 64, 3, 0, 0 } 52c3b2fdd0SAndreas Klinger }; 53c3b2fdd0SAndreas Klinger 54c3b2fdd0SAndreas Klinger static int hx711_get_gain_to_pulse(int gain) 55c3b2fdd0SAndreas Klinger { 56c3b2fdd0SAndreas Klinger int i; 57c3b2fdd0SAndreas Klinger 58c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 59c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].gain == gain) 60c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].gain_pulse; 61c3b2fdd0SAndreas Klinger return 1; 62c3b2fdd0SAndreas Klinger } 63c3b2fdd0SAndreas Klinger 64c3b2fdd0SAndreas Klinger static int hx711_get_gain_to_scale(int gain) 65c3b2fdd0SAndreas Klinger { 66c3b2fdd0SAndreas Klinger int i; 67c3b2fdd0SAndreas Klinger 68c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 69c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].gain == gain) 70c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].scale; 71c3b2fdd0SAndreas Klinger return 0; 72c3b2fdd0SAndreas Klinger } 73c3b2fdd0SAndreas Klinger 74c3b2fdd0SAndreas Klinger static int hx711_get_scale_to_gain(int scale) 75c3b2fdd0SAndreas Klinger { 76c3b2fdd0SAndreas Klinger int i; 77c3b2fdd0SAndreas Klinger 78c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 79c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].scale == scale) 80c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].gain; 81c3b2fdd0SAndreas Klinger return -EINVAL; 82c3b2fdd0SAndreas Klinger } 83c3b2fdd0SAndreas Klinger 84c3b2fdd0SAndreas Klinger struct hx711_data { 85c3b2fdd0SAndreas Klinger struct device *dev; 86c3b2fdd0SAndreas Klinger struct gpio_desc *gpiod_pd_sck; 87c3b2fdd0SAndreas Klinger struct gpio_desc *gpiod_dout; 88c3b2fdd0SAndreas Klinger struct regulator *reg_avdd; 89c3b2fdd0SAndreas Klinger int gain_set; /* gain set on device */ 90c3b2fdd0SAndreas Klinger int gain_chan_a; /* gain for channel A */ 91c3b2fdd0SAndreas Klinger struct mutex lock; 92c3b2fdd0SAndreas Klinger }; 93c3b2fdd0SAndreas Klinger 94c3b2fdd0SAndreas Klinger static int hx711_cycle(struct hx711_data *hx711_data) 95c3b2fdd0SAndreas Klinger { 96c3b2fdd0SAndreas Klinger int val; 97c3b2fdd0SAndreas Klinger 98c3b2fdd0SAndreas Klinger /* 99c3b2fdd0SAndreas Klinger * if preempted for more then 60us while PD_SCK is high: 100c3b2fdd0SAndreas Klinger * hx711 is going in reset 101c3b2fdd0SAndreas Klinger * ==> measuring is false 102c3b2fdd0SAndreas Klinger */ 103c3b2fdd0SAndreas Klinger preempt_disable(); 104c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 1); 105c3b2fdd0SAndreas Klinger val = gpiod_get_value(hx711_data->gpiod_dout); 106c3b2fdd0SAndreas Klinger /* 107c3b2fdd0SAndreas Klinger * here we are not waiting for 0.2 us as suggested by the datasheet, 108c3b2fdd0SAndreas Klinger * because the oscilloscope showed in a test scenario 109c3b2fdd0SAndreas Klinger * at least 1.15 us for PD_SCK high (T3 in datasheet) 110c3b2fdd0SAndreas Klinger * and 0.56 us for PD_SCK low on TI Sitara with 800 MHz 111c3b2fdd0SAndreas Klinger */ 112c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 0); 113c3b2fdd0SAndreas Klinger preempt_enable(); 114c3b2fdd0SAndreas Klinger 115c3b2fdd0SAndreas Klinger return val; 116c3b2fdd0SAndreas Klinger } 117c3b2fdd0SAndreas Klinger 118c3b2fdd0SAndreas Klinger static int hx711_read(struct hx711_data *hx711_data) 119c3b2fdd0SAndreas Klinger { 120c3b2fdd0SAndreas Klinger int i, ret; 121c3b2fdd0SAndreas Klinger int value = 0; 122c3b2fdd0SAndreas Klinger int val = gpiod_get_value(hx711_data->gpiod_dout); 123c3b2fdd0SAndreas Klinger 124c3b2fdd0SAndreas Klinger /* we double check if it's really down */ 125c3b2fdd0SAndreas Klinger if (val) 126c3b2fdd0SAndreas Klinger return -EIO; 127c3b2fdd0SAndreas Klinger 128c3b2fdd0SAndreas Klinger for (i = 0; i < 24; i++) { 129c3b2fdd0SAndreas Klinger value <<= 1; 130c3b2fdd0SAndreas Klinger ret = hx711_cycle(hx711_data); 131c3b2fdd0SAndreas Klinger if (ret) 132c3b2fdd0SAndreas Klinger value++; 133c3b2fdd0SAndreas Klinger } 134c3b2fdd0SAndreas Klinger 135c3b2fdd0SAndreas Klinger value ^= 0x800000; 136c3b2fdd0SAndreas Klinger 137c3b2fdd0SAndreas Klinger for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++) 138c3b2fdd0SAndreas Klinger hx711_cycle(hx711_data); 139c3b2fdd0SAndreas Klinger 140c3b2fdd0SAndreas Klinger return value; 141c3b2fdd0SAndreas Klinger } 142c3b2fdd0SAndreas Klinger 143c3b2fdd0SAndreas Klinger static int hx711_wait_for_ready(struct hx711_data *hx711_data) 144c3b2fdd0SAndreas Klinger { 145c3b2fdd0SAndreas Klinger int i, val; 146c3b2fdd0SAndreas Klinger 147c3b2fdd0SAndreas Klinger /* 148c3b2fdd0SAndreas Klinger * a maximum reset cycle time of 56 ms was measured. 149c3b2fdd0SAndreas Klinger * we round it up to 100 ms 150c3b2fdd0SAndreas Klinger */ 151c3b2fdd0SAndreas Klinger for (i = 0; i < 100; i++) { 152c3b2fdd0SAndreas Klinger val = gpiod_get_value(hx711_data->gpiod_dout); 153c3b2fdd0SAndreas Klinger if (!val) 154c3b2fdd0SAndreas Klinger break; 155c3b2fdd0SAndreas Klinger /* sleep at least 1 ms */ 156c3b2fdd0SAndreas Klinger msleep(1); 157c3b2fdd0SAndreas Klinger } 158c3b2fdd0SAndreas Klinger if (val) 159c3b2fdd0SAndreas Klinger return -EIO; 160c3b2fdd0SAndreas Klinger 161c3b2fdd0SAndreas Klinger return 0; 162c3b2fdd0SAndreas Klinger } 163c3b2fdd0SAndreas Klinger 164c3b2fdd0SAndreas Klinger static int hx711_reset(struct hx711_data *hx711_data) 165c3b2fdd0SAndreas Klinger { 166c3b2fdd0SAndreas Klinger int ret; 167c3b2fdd0SAndreas Klinger int val = gpiod_get_value(hx711_data->gpiod_dout); 168c3b2fdd0SAndreas Klinger 169c3b2fdd0SAndreas Klinger if (val) { 170c3b2fdd0SAndreas Klinger /* 171c3b2fdd0SAndreas Klinger * an examination with the oszilloscope indicated 172c3b2fdd0SAndreas Klinger * that the first value read after the reset is not stable 173c3b2fdd0SAndreas Klinger * if we reset too short; 174c3b2fdd0SAndreas Klinger * the shorter the reset cycle 175c3b2fdd0SAndreas Klinger * the less reliable the first value after reset is; 176c3b2fdd0SAndreas Klinger * there were no problems encountered with a value 177c3b2fdd0SAndreas Klinger * of 10 ms or higher 178c3b2fdd0SAndreas Klinger */ 179c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 1); 180c3b2fdd0SAndreas Klinger msleep(10); 181c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 0); 182c3b2fdd0SAndreas Klinger 183c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 184c3b2fdd0SAndreas Klinger if (ret) 185c3b2fdd0SAndreas Klinger return ret; 186c3b2fdd0SAndreas Klinger /* 187c3b2fdd0SAndreas Klinger * after a reset the gain is 128 so we do a dummy read 188c3b2fdd0SAndreas Klinger * to set the gain for the next read 189c3b2fdd0SAndreas Klinger */ 190c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 191c3b2fdd0SAndreas Klinger if (ret < 0) 192c3b2fdd0SAndreas Klinger return ret; 193c3b2fdd0SAndreas Klinger 194c3b2fdd0SAndreas Klinger /* 195c3b2fdd0SAndreas Klinger * after a dummy read we need to wait vor readiness 196c3b2fdd0SAndreas Klinger * for not mixing gain pulses with the clock 197c3b2fdd0SAndreas Klinger */ 198c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 199c3b2fdd0SAndreas Klinger if (ret) 200c3b2fdd0SAndreas Klinger return ret; 201c3b2fdd0SAndreas Klinger } 202c3b2fdd0SAndreas Klinger 203c3b2fdd0SAndreas Klinger return val; 204c3b2fdd0SAndreas Klinger } 205c3b2fdd0SAndreas Klinger 206c3b2fdd0SAndreas Klinger static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan) 207c3b2fdd0SAndreas Klinger { 208c3b2fdd0SAndreas Klinger int ret; 209c3b2fdd0SAndreas Klinger 210c3b2fdd0SAndreas Klinger if (chan == 0) { 211c3b2fdd0SAndreas Klinger if (hx711_data->gain_set == 32) { 212c3b2fdd0SAndreas Klinger hx711_data->gain_set = hx711_data->gain_chan_a; 213c3b2fdd0SAndreas Klinger 214c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 215c3b2fdd0SAndreas Klinger if (ret < 0) 216c3b2fdd0SAndreas Klinger return ret; 217c3b2fdd0SAndreas Klinger 218c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 219c3b2fdd0SAndreas Klinger if (ret) 220c3b2fdd0SAndreas Klinger return ret; 221c3b2fdd0SAndreas Klinger } 222c3b2fdd0SAndreas Klinger } else { 223c3b2fdd0SAndreas Klinger if (hx711_data->gain_set != 32) { 224c3b2fdd0SAndreas Klinger hx711_data->gain_set = 32; 225c3b2fdd0SAndreas Klinger 226c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 227c3b2fdd0SAndreas Klinger if (ret < 0) 228c3b2fdd0SAndreas Klinger return ret; 229c3b2fdd0SAndreas Klinger 230c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 231c3b2fdd0SAndreas Klinger if (ret) 232c3b2fdd0SAndreas Klinger return ret; 233c3b2fdd0SAndreas Klinger } 234c3b2fdd0SAndreas Klinger } 235c3b2fdd0SAndreas Klinger 236c3b2fdd0SAndreas Klinger return 0; 237c3b2fdd0SAndreas Klinger } 238c3b2fdd0SAndreas Klinger 239c3b2fdd0SAndreas Klinger static int hx711_read_raw(struct iio_dev *indio_dev, 240c3b2fdd0SAndreas Klinger const struct iio_chan_spec *chan, 241c3b2fdd0SAndreas Klinger int *val, int *val2, long mask) 242c3b2fdd0SAndreas Klinger { 243c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data = iio_priv(indio_dev); 244c3b2fdd0SAndreas Klinger int ret; 245c3b2fdd0SAndreas Klinger 246c3b2fdd0SAndreas Klinger switch (mask) { 247c3b2fdd0SAndreas Klinger case IIO_CHAN_INFO_RAW: 248c3b2fdd0SAndreas Klinger mutex_lock(&hx711_data->lock); 249c3b2fdd0SAndreas Klinger 250c3b2fdd0SAndreas Klinger /* 251c3b2fdd0SAndreas Klinger * hx711_reset() must be called from here 252c3b2fdd0SAndreas Klinger * because it could be calling hx711_read() by itself 253c3b2fdd0SAndreas Klinger */ 254c3b2fdd0SAndreas Klinger if (hx711_reset(hx711_data)) { 255c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 256c3b2fdd0SAndreas Klinger dev_err(hx711_data->dev, "reset failed!"); 257c3b2fdd0SAndreas Klinger return -EIO; 258c3b2fdd0SAndreas Klinger } 259c3b2fdd0SAndreas Klinger 260c3b2fdd0SAndreas Klinger ret = hx711_set_gain_for_channel(hx711_data, chan->channel); 261c3b2fdd0SAndreas Klinger if (ret < 0) { 262c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 263c3b2fdd0SAndreas Klinger return ret; 264c3b2fdd0SAndreas Klinger } 265c3b2fdd0SAndreas Klinger 266c3b2fdd0SAndreas Klinger *val = hx711_read(hx711_data); 267c3b2fdd0SAndreas Klinger 268c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 269c3b2fdd0SAndreas Klinger 270c3b2fdd0SAndreas Klinger if (*val < 0) 271c3b2fdd0SAndreas Klinger return *val; 272c3b2fdd0SAndreas Klinger return IIO_VAL_INT; 273c3b2fdd0SAndreas Klinger case IIO_CHAN_INFO_SCALE: 274c3b2fdd0SAndreas Klinger *val = 0; 275c3b2fdd0SAndreas Klinger mutex_lock(&hx711_data->lock); 276c3b2fdd0SAndreas Klinger 277c3b2fdd0SAndreas Klinger *val2 = hx711_get_gain_to_scale(hx711_data->gain_set); 278c3b2fdd0SAndreas Klinger 279c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 280c3b2fdd0SAndreas Klinger 281c3b2fdd0SAndreas Klinger return IIO_VAL_INT_PLUS_NANO; 282c3b2fdd0SAndreas Klinger default: 283c3b2fdd0SAndreas Klinger return -EINVAL; 284c3b2fdd0SAndreas Klinger } 285c3b2fdd0SAndreas Klinger } 286c3b2fdd0SAndreas Klinger 287c3b2fdd0SAndreas Klinger static int hx711_write_raw(struct iio_dev *indio_dev, 288c3b2fdd0SAndreas Klinger struct iio_chan_spec const *chan, 289c3b2fdd0SAndreas Klinger int val, 290c3b2fdd0SAndreas Klinger int val2, 291c3b2fdd0SAndreas Klinger long mask) 292c3b2fdd0SAndreas Klinger { 293c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data = iio_priv(indio_dev); 294c3b2fdd0SAndreas Klinger int ret; 295c3b2fdd0SAndreas Klinger int gain; 296c3b2fdd0SAndreas Klinger 297c3b2fdd0SAndreas Klinger switch (mask) { 298c3b2fdd0SAndreas Klinger case IIO_CHAN_INFO_SCALE: 299c3b2fdd0SAndreas Klinger /* 300c3b2fdd0SAndreas Klinger * a scale greater than 1 mV per LSB is not possible 301c3b2fdd0SAndreas Klinger * with the HX711, therefore val must be 0 302c3b2fdd0SAndreas Klinger */ 303c3b2fdd0SAndreas Klinger if (val != 0) 304c3b2fdd0SAndreas Klinger return -EINVAL; 305c3b2fdd0SAndreas Klinger 306c3b2fdd0SAndreas Klinger mutex_lock(&hx711_data->lock); 307c3b2fdd0SAndreas Klinger 308c3b2fdd0SAndreas Klinger gain = hx711_get_scale_to_gain(val2); 309c3b2fdd0SAndreas Klinger if (gain < 0) { 310c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 311c3b2fdd0SAndreas Klinger return gain; 312c3b2fdd0SAndreas Klinger } 313c3b2fdd0SAndreas Klinger 314c3b2fdd0SAndreas Klinger if (gain != hx711_data->gain_set) { 315c3b2fdd0SAndreas Klinger hx711_data->gain_set = gain; 316c3b2fdd0SAndreas Klinger if (gain != 32) 317c3b2fdd0SAndreas Klinger hx711_data->gain_chan_a = gain; 318c3b2fdd0SAndreas Klinger 319c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 320c3b2fdd0SAndreas Klinger if (ret < 0) { 321c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 322c3b2fdd0SAndreas Klinger return ret; 323c3b2fdd0SAndreas Klinger } 324c3b2fdd0SAndreas Klinger } 325c3b2fdd0SAndreas Klinger 326c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 327c3b2fdd0SAndreas Klinger return 0; 328c3b2fdd0SAndreas Klinger default: 329c3b2fdd0SAndreas Klinger return -EINVAL; 330c3b2fdd0SAndreas Klinger } 331c3b2fdd0SAndreas Klinger 332c3b2fdd0SAndreas Klinger return 0; 333c3b2fdd0SAndreas Klinger } 334c3b2fdd0SAndreas Klinger 335c3b2fdd0SAndreas Klinger static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev, 336c3b2fdd0SAndreas Klinger struct iio_chan_spec const *chan, 337c3b2fdd0SAndreas Klinger long mask) 338c3b2fdd0SAndreas Klinger { 339c3b2fdd0SAndreas Klinger return IIO_VAL_INT_PLUS_NANO; 340c3b2fdd0SAndreas Klinger } 341c3b2fdd0SAndreas Klinger 342c3b2fdd0SAndreas Klinger static ssize_t hx711_scale_available_show(struct device *dev, 343c3b2fdd0SAndreas Klinger struct device_attribute *attr, 344c3b2fdd0SAndreas Klinger char *buf) 345c3b2fdd0SAndreas Klinger { 346c3b2fdd0SAndreas Klinger struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr); 347c3b2fdd0SAndreas Klinger int channel = iio_attr->address; 348c3b2fdd0SAndreas Klinger int i, len = 0; 349c3b2fdd0SAndreas Klinger 350c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 351c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].channel == channel) 352c3b2fdd0SAndreas Klinger len += sprintf(buf + len, "0.%09d ", 353c3b2fdd0SAndreas Klinger hx711_gain_to_scale[i].scale); 354c3b2fdd0SAndreas Klinger 355c3b2fdd0SAndreas Klinger len += sprintf(buf + len, "\n"); 356c3b2fdd0SAndreas Klinger 357c3b2fdd0SAndreas Klinger return len; 358c3b2fdd0SAndreas Klinger } 359c3b2fdd0SAndreas Klinger 360c3b2fdd0SAndreas Klinger static IIO_DEVICE_ATTR(in_voltage0_scale_available, S_IRUGO, 361c3b2fdd0SAndreas Klinger hx711_scale_available_show, NULL, 0); 362c3b2fdd0SAndreas Klinger 363c3b2fdd0SAndreas Klinger static IIO_DEVICE_ATTR(in_voltage1_scale_available, S_IRUGO, 364c3b2fdd0SAndreas Klinger hx711_scale_available_show, NULL, 1); 365c3b2fdd0SAndreas Klinger 366c3b2fdd0SAndreas Klinger static struct attribute *hx711_attributes[] = { 367c3b2fdd0SAndreas Klinger &iio_dev_attr_in_voltage0_scale_available.dev_attr.attr, 368c3b2fdd0SAndreas Klinger &iio_dev_attr_in_voltage1_scale_available.dev_attr.attr, 369c3b2fdd0SAndreas Klinger NULL, 370c3b2fdd0SAndreas Klinger }; 371c3b2fdd0SAndreas Klinger 372c3b2fdd0SAndreas Klinger static struct attribute_group hx711_attribute_group = { 373c3b2fdd0SAndreas Klinger .attrs = hx711_attributes, 374c3b2fdd0SAndreas Klinger }; 375c3b2fdd0SAndreas Klinger 376c3b2fdd0SAndreas Klinger static const struct iio_info hx711_iio_info = { 377c3b2fdd0SAndreas Klinger .driver_module = THIS_MODULE, 378c3b2fdd0SAndreas Klinger .read_raw = hx711_read_raw, 379c3b2fdd0SAndreas Klinger .write_raw = hx711_write_raw, 380c3b2fdd0SAndreas Klinger .write_raw_get_fmt = hx711_write_raw_get_fmt, 381c3b2fdd0SAndreas Klinger .attrs = &hx711_attribute_group, 382c3b2fdd0SAndreas Klinger }; 383c3b2fdd0SAndreas Klinger 384c3b2fdd0SAndreas Klinger static const struct iio_chan_spec hx711_chan_spec[] = { 385c3b2fdd0SAndreas Klinger { 386c3b2fdd0SAndreas Klinger .type = IIO_VOLTAGE, 387c3b2fdd0SAndreas Klinger .channel = 0, 388c3b2fdd0SAndreas Klinger .indexed = 1, 389c3b2fdd0SAndreas Klinger .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 390c3b2fdd0SAndreas Klinger .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 391c3b2fdd0SAndreas Klinger }, 392c3b2fdd0SAndreas Klinger { 393c3b2fdd0SAndreas Klinger .type = IIO_VOLTAGE, 394c3b2fdd0SAndreas Klinger .channel = 1, 395c3b2fdd0SAndreas Klinger .indexed = 1, 396c3b2fdd0SAndreas Klinger .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 397c3b2fdd0SAndreas Klinger .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 398c3b2fdd0SAndreas Klinger }, 399c3b2fdd0SAndreas Klinger }; 400c3b2fdd0SAndreas Klinger 401c3b2fdd0SAndreas Klinger static int hx711_probe(struct platform_device *pdev) 402c3b2fdd0SAndreas Klinger { 403c3b2fdd0SAndreas Klinger struct device *dev = &pdev->dev; 404c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data; 405c3b2fdd0SAndreas Klinger struct iio_dev *indio_dev; 406c3b2fdd0SAndreas Klinger int ret; 407c3b2fdd0SAndreas Klinger int i; 408c3b2fdd0SAndreas Klinger 409c3b2fdd0SAndreas Klinger indio_dev = devm_iio_device_alloc(dev, sizeof(struct hx711_data)); 410c3b2fdd0SAndreas Klinger if (!indio_dev) { 411c3b2fdd0SAndreas Klinger dev_err(dev, "failed to allocate IIO device\n"); 412c3b2fdd0SAndreas Klinger return -ENOMEM; 413c3b2fdd0SAndreas Klinger } 414c3b2fdd0SAndreas Klinger 415c3b2fdd0SAndreas Klinger hx711_data = iio_priv(indio_dev); 416c3b2fdd0SAndreas Klinger hx711_data->dev = dev; 417c3b2fdd0SAndreas Klinger 418c3b2fdd0SAndreas Klinger mutex_init(&hx711_data->lock); 419c3b2fdd0SAndreas Klinger 420c3b2fdd0SAndreas Klinger /* 421c3b2fdd0SAndreas Klinger * PD_SCK stands for power down and serial clock input of HX711 422c3b2fdd0SAndreas Klinger * in the driver it is an output 423c3b2fdd0SAndreas Klinger */ 424c3b2fdd0SAndreas Klinger hx711_data->gpiod_pd_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW); 425c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->gpiod_pd_sck)) { 426c3b2fdd0SAndreas Klinger dev_err(dev, "failed to get sck-gpiod: err=%ld\n", 427c3b2fdd0SAndreas Klinger PTR_ERR(hx711_data->gpiod_pd_sck)); 428c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->gpiod_pd_sck); 429c3b2fdd0SAndreas Klinger } 430c3b2fdd0SAndreas Klinger 431c3b2fdd0SAndreas Klinger /* 432c3b2fdd0SAndreas Klinger * DOUT stands for serial data output of HX711 433c3b2fdd0SAndreas Klinger * for the driver it is an input 434c3b2fdd0SAndreas Klinger */ 435c3b2fdd0SAndreas Klinger hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_IN); 436c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->gpiod_dout)) { 437c3b2fdd0SAndreas Klinger dev_err(dev, "failed to get dout-gpiod: err=%ld\n", 438c3b2fdd0SAndreas Klinger PTR_ERR(hx711_data->gpiod_dout)); 439c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->gpiod_dout); 440c3b2fdd0SAndreas Klinger } 441c3b2fdd0SAndreas Klinger 442c3b2fdd0SAndreas Klinger hx711_data->reg_avdd = devm_regulator_get(dev, "avdd"); 443c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->reg_avdd)) 444c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->reg_avdd); 445c3b2fdd0SAndreas Klinger 446c3b2fdd0SAndreas Klinger ret = regulator_enable(hx711_data->reg_avdd); 447c3b2fdd0SAndreas Klinger if (ret < 0) 448c3b2fdd0SAndreas Klinger return ret; 449c3b2fdd0SAndreas Klinger 450c3b2fdd0SAndreas Klinger /* 451c3b2fdd0SAndreas Klinger * with 452c3b2fdd0SAndreas Klinger * full scale differential input range: AVDD / GAIN 453c3b2fdd0SAndreas Klinger * full scale output data: 2^24 454c3b2fdd0SAndreas Klinger * we can say: 455c3b2fdd0SAndreas Klinger * AVDD / GAIN = 2^24 456c3b2fdd0SAndreas Klinger * therefore: 457c3b2fdd0SAndreas Klinger * 1 LSB = AVDD / GAIN / 2^24 458c3b2fdd0SAndreas Klinger * AVDD is in uV, but we need 10^-9 mV 459c3b2fdd0SAndreas Klinger * approximately to fit into a 32 bit number: 460c3b2fdd0SAndreas Klinger * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV] 461c3b2fdd0SAndreas Klinger */ 462c3b2fdd0SAndreas Klinger ret = regulator_get_voltage(hx711_data->reg_avdd); 463c3b2fdd0SAndreas Klinger if (ret < 0) { 464c3b2fdd0SAndreas Klinger regulator_disable(hx711_data->reg_avdd); 465c3b2fdd0SAndreas Klinger return ret; 466c3b2fdd0SAndreas Klinger } 467c3b2fdd0SAndreas Klinger /* we need 10^-9 mV */ 468c3b2fdd0SAndreas Klinger ret *= 100; 469c3b2fdd0SAndreas Klinger 470c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 471c3b2fdd0SAndreas Klinger hx711_gain_to_scale[i].scale = 472c3b2fdd0SAndreas Klinger ret / hx711_gain_to_scale[i].gain / 1678; 473c3b2fdd0SAndreas Klinger 474c3b2fdd0SAndreas Klinger hx711_data->gain_set = 128; 475c3b2fdd0SAndreas Klinger hx711_data->gain_chan_a = 128; 476c3b2fdd0SAndreas Klinger 477c3b2fdd0SAndreas Klinger platform_set_drvdata(pdev, indio_dev); 478c3b2fdd0SAndreas Klinger 479c3b2fdd0SAndreas Klinger indio_dev->name = "hx711"; 480c3b2fdd0SAndreas Klinger indio_dev->dev.parent = &pdev->dev; 481c3b2fdd0SAndreas Klinger indio_dev->info = &hx711_iio_info; 482c3b2fdd0SAndreas Klinger indio_dev->modes = INDIO_DIRECT_MODE; 483c3b2fdd0SAndreas Klinger indio_dev->channels = hx711_chan_spec; 484c3b2fdd0SAndreas Klinger indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec); 485c3b2fdd0SAndreas Klinger 486c3b2fdd0SAndreas Klinger ret = iio_device_register(indio_dev); 487c3b2fdd0SAndreas Klinger if (ret < 0) { 488c3b2fdd0SAndreas Klinger dev_err(dev, "Couldn't register the device\n"); 489c3b2fdd0SAndreas Klinger regulator_disable(hx711_data->reg_avdd); 490c3b2fdd0SAndreas Klinger } 491c3b2fdd0SAndreas Klinger 492c3b2fdd0SAndreas Klinger return ret; 493c3b2fdd0SAndreas Klinger } 494c3b2fdd0SAndreas Klinger 495c3b2fdd0SAndreas Klinger static int hx711_remove(struct platform_device *pdev) 496c3b2fdd0SAndreas Klinger { 497c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data; 498c3b2fdd0SAndreas Klinger struct iio_dev *indio_dev; 499c3b2fdd0SAndreas Klinger 500c3b2fdd0SAndreas Klinger indio_dev = platform_get_drvdata(pdev); 501c3b2fdd0SAndreas Klinger hx711_data = iio_priv(indio_dev); 502c3b2fdd0SAndreas Klinger 503c3b2fdd0SAndreas Klinger iio_device_unregister(indio_dev); 504c3b2fdd0SAndreas Klinger 505c3b2fdd0SAndreas Klinger regulator_disable(hx711_data->reg_avdd); 506c3b2fdd0SAndreas Klinger 507c3b2fdd0SAndreas Klinger return 0; 508c3b2fdd0SAndreas Klinger } 509c3b2fdd0SAndreas Klinger 510c3b2fdd0SAndreas Klinger static const struct of_device_id of_hx711_match[] = { 511c3b2fdd0SAndreas Klinger { .compatible = "avia,hx711", }, 512c3b2fdd0SAndreas Klinger {}, 513c3b2fdd0SAndreas Klinger }; 514c3b2fdd0SAndreas Klinger 515c3b2fdd0SAndreas Klinger MODULE_DEVICE_TABLE(of, of_hx711_match); 516c3b2fdd0SAndreas Klinger 517c3b2fdd0SAndreas Klinger static struct platform_driver hx711_driver = { 518c3b2fdd0SAndreas Klinger .probe = hx711_probe, 519c3b2fdd0SAndreas Klinger .remove = hx711_remove, 520c3b2fdd0SAndreas Klinger .driver = { 521c3b2fdd0SAndreas Klinger .name = "hx711-gpio", 522c3b2fdd0SAndreas Klinger .of_match_table = of_hx711_match, 523c3b2fdd0SAndreas Klinger }, 524c3b2fdd0SAndreas Klinger }; 525c3b2fdd0SAndreas Klinger 526c3b2fdd0SAndreas Klinger module_platform_driver(hx711_driver); 527c3b2fdd0SAndreas Klinger 528c3b2fdd0SAndreas Klinger MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>"); 529c3b2fdd0SAndreas Klinger MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells"); 530c3b2fdd0SAndreas Klinger MODULE_LICENSE("GPL"); 531c3b2fdd0SAndreas Klinger MODULE_ALIAS("platform:hx711-gpio"); 532c3b2fdd0SAndreas Klinger 533