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> 27d3bf6045SAndreas Klinger #include <linux/iio/buffer.h> 28d3bf6045SAndreas Klinger #include <linux/iio/trigger_consumer.h> 29d3bf6045SAndreas Klinger #include <linux/iio/triggered_buffer.h> 30c3b2fdd0SAndreas Klinger #include <linux/gpio/consumer.h> 31c3b2fdd0SAndreas Klinger #include <linux/regulator/consumer.h> 32c3b2fdd0SAndreas Klinger 33c3b2fdd0SAndreas Klinger /* gain to pulse and scale conversion */ 34c3b2fdd0SAndreas Klinger #define HX711_GAIN_MAX 3 35c3b2fdd0SAndreas Klinger 36c3b2fdd0SAndreas Klinger struct hx711_gain_to_scale { 37c3b2fdd0SAndreas Klinger int gain; 38c3b2fdd0SAndreas Klinger int gain_pulse; 39c3b2fdd0SAndreas Klinger int scale; 40c3b2fdd0SAndreas Klinger int channel; 41c3b2fdd0SAndreas Klinger }; 42c3b2fdd0SAndreas Klinger 43c3b2fdd0SAndreas Klinger /* 44c3b2fdd0SAndreas Klinger * .scale depends on AVDD which in turn is known as soon as the regulator 45c3b2fdd0SAndreas Klinger * is available 46c3b2fdd0SAndreas Klinger * therefore we set .scale in hx711_probe() 47c3b2fdd0SAndreas Klinger * 48c3b2fdd0SAndreas Klinger * channel A in documentation is channel 0 in source code 49c3b2fdd0SAndreas Klinger * channel B in documentation is channel 1 in source code 50c3b2fdd0SAndreas Klinger */ 51c3b2fdd0SAndreas Klinger static struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = { 52c3b2fdd0SAndreas Klinger { 128, 1, 0, 0 }, 53c3b2fdd0SAndreas Klinger { 32, 2, 0, 1 }, 54c3b2fdd0SAndreas Klinger { 64, 3, 0, 0 } 55c3b2fdd0SAndreas Klinger }; 56c3b2fdd0SAndreas Klinger 57c3b2fdd0SAndreas Klinger static int hx711_get_gain_to_pulse(int gain) 58c3b2fdd0SAndreas Klinger { 59c3b2fdd0SAndreas Klinger int i; 60c3b2fdd0SAndreas Klinger 61c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 62c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].gain == gain) 63c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].gain_pulse; 64c3b2fdd0SAndreas Klinger return 1; 65c3b2fdd0SAndreas Klinger } 66c3b2fdd0SAndreas Klinger 67c3b2fdd0SAndreas Klinger static int hx711_get_gain_to_scale(int gain) 68c3b2fdd0SAndreas Klinger { 69c3b2fdd0SAndreas Klinger int i; 70c3b2fdd0SAndreas Klinger 71c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 72c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].gain == gain) 73c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].scale; 74c3b2fdd0SAndreas Klinger return 0; 75c3b2fdd0SAndreas Klinger } 76c3b2fdd0SAndreas Klinger 77c3b2fdd0SAndreas Klinger static int hx711_get_scale_to_gain(int scale) 78c3b2fdd0SAndreas Klinger { 79c3b2fdd0SAndreas Klinger int i; 80c3b2fdd0SAndreas Klinger 81c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 82c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].scale == scale) 83c3b2fdd0SAndreas Klinger return hx711_gain_to_scale[i].gain; 84c3b2fdd0SAndreas Klinger return -EINVAL; 85c3b2fdd0SAndreas Klinger } 86c3b2fdd0SAndreas Klinger 87c3b2fdd0SAndreas Klinger struct hx711_data { 88c3b2fdd0SAndreas Klinger struct device *dev; 89c3b2fdd0SAndreas Klinger struct gpio_desc *gpiod_pd_sck; 90c3b2fdd0SAndreas Klinger struct gpio_desc *gpiod_dout; 91c3b2fdd0SAndreas Klinger struct regulator *reg_avdd; 92c3b2fdd0SAndreas Klinger int gain_set; /* gain set on device */ 93c3b2fdd0SAndreas Klinger int gain_chan_a; /* gain for channel A */ 94c3b2fdd0SAndreas Klinger struct mutex lock; 95d3bf6045SAndreas Klinger /* 96d3bf6045SAndreas Klinger * triggered buffer 97d3bf6045SAndreas Klinger * 2x32-bit channel + 64-bit timestamp 98d3bf6045SAndreas Klinger */ 99d3bf6045SAndreas Klinger u32 buffer[4]; 100c3b2fdd0SAndreas Klinger }; 101c3b2fdd0SAndreas Klinger 102c3b2fdd0SAndreas Klinger static int hx711_cycle(struct hx711_data *hx711_data) 103c3b2fdd0SAndreas Klinger { 104c3b2fdd0SAndreas Klinger int val; 105c3b2fdd0SAndreas Klinger 106c3b2fdd0SAndreas Klinger /* 107c3b2fdd0SAndreas Klinger * if preempted for more then 60us while PD_SCK is high: 108c3b2fdd0SAndreas Klinger * hx711 is going in reset 109c3b2fdd0SAndreas Klinger * ==> measuring is false 110c3b2fdd0SAndreas Klinger */ 111c3b2fdd0SAndreas Klinger preempt_disable(); 112c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 1); 113c3b2fdd0SAndreas Klinger val = gpiod_get_value(hx711_data->gpiod_dout); 114c3b2fdd0SAndreas Klinger /* 115c3b2fdd0SAndreas Klinger * here we are not waiting for 0.2 us as suggested by the datasheet, 116c3b2fdd0SAndreas Klinger * because the oscilloscope showed in a test scenario 117c3b2fdd0SAndreas Klinger * at least 1.15 us for PD_SCK high (T3 in datasheet) 118c3b2fdd0SAndreas Klinger * and 0.56 us for PD_SCK low on TI Sitara with 800 MHz 119c3b2fdd0SAndreas Klinger */ 120c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 0); 121c3b2fdd0SAndreas Klinger preempt_enable(); 122c3b2fdd0SAndreas Klinger 123c3b2fdd0SAndreas Klinger return val; 124c3b2fdd0SAndreas Klinger } 125c3b2fdd0SAndreas Klinger 126c3b2fdd0SAndreas Klinger static int hx711_read(struct hx711_data *hx711_data) 127c3b2fdd0SAndreas Klinger { 128c3b2fdd0SAndreas Klinger int i, ret; 129c3b2fdd0SAndreas Klinger int value = 0; 130c3b2fdd0SAndreas Klinger int val = gpiod_get_value(hx711_data->gpiod_dout); 131c3b2fdd0SAndreas Klinger 132c3b2fdd0SAndreas Klinger /* we double check if it's really down */ 133c3b2fdd0SAndreas Klinger if (val) 134c3b2fdd0SAndreas Klinger return -EIO; 135c3b2fdd0SAndreas Klinger 136c3b2fdd0SAndreas Klinger for (i = 0; i < 24; i++) { 137c3b2fdd0SAndreas Klinger value <<= 1; 138c3b2fdd0SAndreas Klinger ret = hx711_cycle(hx711_data); 139c3b2fdd0SAndreas Klinger if (ret) 140c3b2fdd0SAndreas Klinger value++; 141c3b2fdd0SAndreas Klinger } 142c3b2fdd0SAndreas Klinger 143c3b2fdd0SAndreas Klinger value ^= 0x800000; 144c3b2fdd0SAndreas Klinger 145c3b2fdd0SAndreas Klinger for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++) 146c3b2fdd0SAndreas Klinger hx711_cycle(hx711_data); 147c3b2fdd0SAndreas Klinger 148c3b2fdd0SAndreas Klinger return value; 149c3b2fdd0SAndreas Klinger } 150c3b2fdd0SAndreas Klinger 151c3b2fdd0SAndreas Klinger static int hx711_wait_for_ready(struct hx711_data *hx711_data) 152c3b2fdd0SAndreas Klinger { 153c3b2fdd0SAndreas Klinger int i, val; 154c3b2fdd0SAndreas Klinger 155c3b2fdd0SAndreas Klinger /* 1561fe899e3SAndreas Klinger * in some rare cases the reset takes quite a long time 1571fe899e3SAndreas Klinger * especially when the channel is changed. 1581fe899e3SAndreas Klinger * Allow up to one second for it 159c3b2fdd0SAndreas Klinger */ 160c3b2fdd0SAndreas Klinger for (i = 0; i < 100; i++) { 161c3b2fdd0SAndreas Klinger val = gpiod_get_value(hx711_data->gpiod_dout); 162c3b2fdd0SAndreas Klinger if (!val) 163c3b2fdd0SAndreas Klinger break; 1641fe899e3SAndreas Klinger /* sleep at least 10 ms */ 1651fe899e3SAndreas Klinger msleep(10); 166c3b2fdd0SAndreas Klinger } 167c3b2fdd0SAndreas Klinger if (val) 168c3b2fdd0SAndreas Klinger return -EIO; 169c3b2fdd0SAndreas Klinger 170c3b2fdd0SAndreas Klinger return 0; 171c3b2fdd0SAndreas Klinger } 172c3b2fdd0SAndreas Klinger 173c3b2fdd0SAndreas Klinger static int hx711_reset(struct hx711_data *hx711_data) 174c3b2fdd0SAndreas Klinger { 175c3b2fdd0SAndreas Klinger int ret; 176c3b2fdd0SAndreas Klinger int val = gpiod_get_value(hx711_data->gpiod_dout); 177c3b2fdd0SAndreas Klinger 178c3b2fdd0SAndreas Klinger if (val) { 179c3b2fdd0SAndreas Klinger /* 180c3b2fdd0SAndreas Klinger * an examination with the oszilloscope indicated 181c3b2fdd0SAndreas Klinger * that the first value read after the reset is not stable 182c3b2fdd0SAndreas Klinger * if we reset too short; 183c3b2fdd0SAndreas Klinger * the shorter the reset cycle 184c3b2fdd0SAndreas Klinger * the less reliable the first value after reset is; 185c3b2fdd0SAndreas Klinger * there were no problems encountered with a value 186c3b2fdd0SAndreas Klinger * of 10 ms or higher 187c3b2fdd0SAndreas Klinger */ 188c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 1); 189c3b2fdd0SAndreas Klinger msleep(10); 190c3b2fdd0SAndreas Klinger gpiod_set_value(hx711_data->gpiod_pd_sck, 0); 191c3b2fdd0SAndreas Klinger 192c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 193c3b2fdd0SAndreas Klinger if (ret) 194c3b2fdd0SAndreas Klinger return ret; 195c3b2fdd0SAndreas Klinger /* 196c3b2fdd0SAndreas Klinger * after a reset the gain is 128 so we do a dummy read 197c3b2fdd0SAndreas Klinger * to set the gain for the next read 198c3b2fdd0SAndreas Klinger */ 199c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 200c3b2fdd0SAndreas Klinger if (ret < 0) 201c3b2fdd0SAndreas Klinger return ret; 202c3b2fdd0SAndreas Klinger 203c3b2fdd0SAndreas Klinger /* 204c3b2fdd0SAndreas Klinger * after a dummy read we need to wait vor readiness 205c3b2fdd0SAndreas Klinger * for not mixing gain pulses with the clock 206c3b2fdd0SAndreas Klinger */ 2071fe899e3SAndreas Klinger val = hx711_wait_for_ready(hx711_data); 208c3b2fdd0SAndreas Klinger } 209c3b2fdd0SAndreas Klinger 210c3b2fdd0SAndreas Klinger return val; 211c3b2fdd0SAndreas Klinger } 212c3b2fdd0SAndreas Klinger 213c3b2fdd0SAndreas Klinger static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan) 214c3b2fdd0SAndreas Klinger { 215c3b2fdd0SAndreas Klinger int ret; 216c3b2fdd0SAndreas Klinger 217c3b2fdd0SAndreas Klinger if (chan == 0) { 218c3b2fdd0SAndreas Klinger if (hx711_data->gain_set == 32) { 219c3b2fdd0SAndreas Klinger hx711_data->gain_set = hx711_data->gain_chan_a; 220c3b2fdd0SAndreas Klinger 221c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 222c3b2fdd0SAndreas Klinger if (ret < 0) 223c3b2fdd0SAndreas Klinger return ret; 224c3b2fdd0SAndreas Klinger 225c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 226c3b2fdd0SAndreas Klinger if (ret) 227c3b2fdd0SAndreas Klinger return ret; 228c3b2fdd0SAndreas Klinger } 229c3b2fdd0SAndreas Klinger } else { 230c3b2fdd0SAndreas Klinger if (hx711_data->gain_set != 32) { 231c3b2fdd0SAndreas Klinger hx711_data->gain_set = 32; 232c3b2fdd0SAndreas Klinger 233c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 234c3b2fdd0SAndreas Klinger if (ret < 0) 235c3b2fdd0SAndreas Klinger return ret; 236c3b2fdd0SAndreas Klinger 237c3b2fdd0SAndreas Klinger ret = hx711_wait_for_ready(hx711_data); 238c3b2fdd0SAndreas Klinger if (ret) 239c3b2fdd0SAndreas Klinger return ret; 240c3b2fdd0SAndreas Klinger } 241c3b2fdd0SAndreas Klinger } 242c3b2fdd0SAndreas Klinger 243c3b2fdd0SAndreas Klinger return 0; 244c3b2fdd0SAndreas Klinger } 245c3b2fdd0SAndreas Klinger 246d3bf6045SAndreas Klinger static int hx711_reset_read(struct hx711_data *hx711_data, int chan) 247c3b2fdd0SAndreas Klinger { 248c3b2fdd0SAndreas Klinger int ret; 249d3bf6045SAndreas Klinger int val; 250c3b2fdd0SAndreas Klinger 251c3b2fdd0SAndreas Klinger /* 252c3b2fdd0SAndreas Klinger * hx711_reset() must be called from here 253c3b2fdd0SAndreas Klinger * because it could be calling hx711_read() by itself 254c3b2fdd0SAndreas Klinger */ 255c3b2fdd0SAndreas Klinger if (hx711_reset(hx711_data)) { 256c3b2fdd0SAndreas Klinger dev_err(hx711_data->dev, "reset failed!"); 257c3b2fdd0SAndreas Klinger return -EIO; 258c3b2fdd0SAndreas Klinger } 259c3b2fdd0SAndreas Klinger 260d3bf6045SAndreas Klinger ret = hx711_set_gain_for_channel(hx711_data, chan); 261d3bf6045SAndreas Klinger if (ret < 0) 262c3b2fdd0SAndreas Klinger return ret; 263d3bf6045SAndreas Klinger 264d3bf6045SAndreas Klinger val = hx711_read(hx711_data); 265d3bf6045SAndreas Klinger 266d3bf6045SAndreas Klinger return val; 267c3b2fdd0SAndreas Klinger } 268c3b2fdd0SAndreas Klinger 269d3bf6045SAndreas Klinger static int hx711_read_raw(struct iio_dev *indio_dev, 270d3bf6045SAndreas Klinger const struct iio_chan_spec *chan, 271d3bf6045SAndreas Klinger int *val, int *val2, long mask) 272d3bf6045SAndreas Klinger { 273d3bf6045SAndreas Klinger struct hx711_data *hx711_data = iio_priv(indio_dev); 274d3bf6045SAndreas Klinger 275d3bf6045SAndreas Klinger switch (mask) { 276d3bf6045SAndreas Klinger case IIO_CHAN_INFO_RAW: 277d3bf6045SAndreas Klinger mutex_lock(&hx711_data->lock); 278d3bf6045SAndreas Klinger 279d3bf6045SAndreas Klinger *val = hx711_reset_read(hx711_data, chan->channel); 280c3b2fdd0SAndreas Klinger 281c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 282c3b2fdd0SAndreas Klinger 283c3b2fdd0SAndreas Klinger if (*val < 0) 284c3b2fdd0SAndreas Klinger return *val; 285c3b2fdd0SAndreas Klinger return IIO_VAL_INT; 286c3b2fdd0SAndreas Klinger case IIO_CHAN_INFO_SCALE: 287c3b2fdd0SAndreas Klinger *val = 0; 288c3b2fdd0SAndreas Klinger mutex_lock(&hx711_data->lock); 289c3b2fdd0SAndreas Klinger 290c3b2fdd0SAndreas Klinger *val2 = hx711_get_gain_to_scale(hx711_data->gain_set); 291c3b2fdd0SAndreas Klinger 292c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 293c3b2fdd0SAndreas Klinger 294c3b2fdd0SAndreas Klinger return IIO_VAL_INT_PLUS_NANO; 295c3b2fdd0SAndreas Klinger default: 296c3b2fdd0SAndreas Klinger return -EINVAL; 297c3b2fdd0SAndreas Klinger } 298c3b2fdd0SAndreas Klinger } 299c3b2fdd0SAndreas Klinger 300c3b2fdd0SAndreas Klinger static int hx711_write_raw(struct iio_dev *indio_dev, 301c3b2fdd0SAndreas Klinger struct iio_chan_spec const *chan, 302c3b2fdd0SAndreas Klinger int val, 303c3b2fdd0SAndreas Klinger int val2, 304c3b2fdd0SAndreas Klinger long mask) 305c3b2fdd0SAndreas Klinger { 306c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data = iio_priv(indio_dev); 307c3b2fdd0SAndreas Klinger int ret; 308c3b2fdd0SAndreas Klinger int gain; 309c3b2fdd0SAndreas Klinger 310c3b2fdd0SAndreas Klinger switch (mask) { 311c3b2fdd0SAndreas Klinger case IIO_CHAN_INFO_SCALE: 312c3b2fdd0SAndreas Klinger /* 313c3b2fdd0SAndreas Klinger * a scale greater than 1 mV per LSB is not possible 314c3b2fdd0SAndreas Klinger * with the HX711, therefore val must be 0 315c3b2fdd0SAndreas Klinger */ 316c3b2fdd0SAndreas Klinger if (val != 0) 317c3b2fdd0SAndreas Klinger return -EINVAL; 318c3b2fdd0SAndreas Klinger 319c3b2fdd0SAndreas Klinger mutex_lock(&hx711_data->lock); 320c3b2fdd0SAndreas Klinger 321c3b2fdd0SAndreas Klinger gain = hx711_get_scale_to_gain(val2); 322c3b2fdd0SAndreas Klinger if (gain < 0) { 323c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 324c3b2fdd0SAndreas Klinger return gain; 325c3b2fdd0SAndreas Klinger } 326c3b2fdd0SAndreas Klinger 327c3b2fdd0SAndreas Klinger if (gain != hx711_data->gain_set) { 328c3b2fdd0SAndreas Klinger hx711_data->gain_set = gain; 329c3b2fdd0SAndreas Klinger if (gain != 32) 330c3b2fdd0SAndreas Klinger hx711_data->gain_chan_a = gain; 331c3b2fdd0SAndreas Klinger 332c3b2fdd0SAndreas Klinger ret = hx711_read(hx711_data); 333c3b2fdd0SAndreas Klinger if (ret < 0) { 334c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 335c3b2fdd0SAndreas Klinger return ret; 336c3b2fdd0SAndreas Klinger } 337c3b2fdd0SAndreas Klinger } 338c3b2fdd0SAndreas Klinger 339c3b2fdd0SAndreas Klinger mutex_unlock(&hx711_data->lock); 340c3b2fdd0SAndreas Klinger return 0; 341c3b2fdd0SAndreas Klinger default: 342c3b2fdd0SAndreas Klinger return -EINVAL; 343c3b2fdd0SAndreas Klinger } 344c3b2fdd0SAndreas Klinger 345c3b2fdd0SAndreas Klinger return 0; 346c3b2fdd0SAndreas Klinger } 347c3b2fdd0SAndreas Klinger 348c3b2fdd0SAndreas Klinger static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev, 349c3b2fdd0SAndreas Klinger struct iio_chan_spec const *chan, 350c3b2fdd0SAndreas Klinger long mask) 351c3b2fdd0SAndreas Klinger { 352c3b2fdd0SAndreas Klinger return IIO_VAL_INT_PLUS_NANO; 353c3b2fdd0SAndreas Klinger } 354c3b2fdd0SAndreas Klinger 355d3bf6045SAndreas Klinger static irqreturn_t hx711_trigger(int irq, void *p) 356d3bf6045SAndreas Klinger { 357d3bf6045SAndreas Klinger struct iio_poll_func *pf = p; 358d3bf6045SAndreas Klinger struct iio_dev *indio_dev = pf->indio_dev; 359d3bf6045SAndreas Klinger struct hx711_data *hx711_data = iio_priv(indio_dev); 360d3bf6045SAndreas Klinger int i, j = 0; 361d3bf6045SAndreas Klinger 362d3bf6045SAndreas Klinger mutex_lock(&hx711_data->lock); 363d3bf6045SAndreas Klinger 364d3bf6045SAndreas Klinger memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer)); 365d3bf6045SAndreas Klinger 366d3bf6045SAndreas Klinger for (i = 0; i < indio_dev->masklength; i++) { 367d3bf6045SAndreas Klinger if (!test_bit(i, indio_dev->active_scan_mask)) 368d3bf6045SAndreas Klinger continue; 369d3bf6045SAndreas Klinger 370d3bf6045SAndreas Klinger hx711_data->buffer[j] = hx711_reset_read(hx711_data, 371d3bf6045SAndreas Klinger indio_dev->channels[i].channel); 372d3bf6045SAndreas Klinger j++; 373d3bf6045SAndreas Klinger } 374d3bf6045SAndreas Klinger 375d3bf6045SAndreas Klinger iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer, 376d3bf6045SAndreas Klinger pf->timestamp); 377d3bf6045SAndreas Klinger 378d3bf6045SAndreas Klinger mutex_unlock(&hx711_data->lock); 379d3bf6045SAndreas Klinger 380d3bf6045SAndreas Klinger iio_trigger_notify_done(indio_dev->trig); 381d3bf6045SAndreas Klinger 382d3bf6045SAndreas Klinger return IRQ_HANDLED; 383d3bf6045SAndreas Klinger } 384d3bf6045SAndreas Klinger 385c3b2fdd0SAndreas Klinger static ssize_t hx711_scale_available_show(struct device *dev, 386c3b2fdd0SAndreas Klinger struct device_attribute *attr, 387c3b2fdd0SAndreas Klinger char *buf) 388c3b2fdd0SAndreas Klinger { 389c3b2fdd0SAndreas Klinger struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr); 390c3b2fdd0SAndreas Klinger int channel = iio_attr->address; 391c3b2fdd0SAndreas Klinger int i, len = 0; 392c3b2fdd0SAndreas Klinger 393c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 394c3b2fdd0SAndreas Klinger if (hx711_gain_to_scale[i].channel == channel) 395c3b2fdd0SAndreas Klinger len += sprintf(buf + len, "0.%09d ", 396c3b2fdd0SAndreas Klinger hx711_gain_to_scale[i].scale); 397c3b2fdd0SAndreas Klinger 398c3b2fdd0SAndreas Klinger len += sprintf(buf + len, "\n"); 399c3b2fdd0SAndreas Klinger 400c3b2fdd0SAndreas Klinger return len; 401c3b2fdd0SAndreas Klinger } 402c3b2fdd0SAndreas Klinger 403c3b2fdd0SAndreas Klinger static IIO_DEVICE_ATTR(in_voltage0_scale_available, S_IRUGO, 404c3b2fdd0SAndreas Klinger hx711_scale_available_show, NULL, 0); 405c3b2fdd0SAndreas Klinger 406c3b2fdd0SAndreas Klinger static IIO_DEVICE_ATTR(in_voltage1_scale_available, S_IRUGO, 407c3b2fdd0SAndreas Klinger hx711_scale_available_show, NULL, 1); 408c3b2fdd0SAndreas Klinger 409c3b2fdd0SAndreas Klinger static struct attribute *hx711_attributes[] = { 410c3b2fdd0SAndreas Klinger &iio_dev_attr_in_voltage0_scale_available.dev_attr.attr, 411c3b2fdd0SAndreas Klinger &iio_dev_attr_in_voltage1_scale_available.dev_attr.attr, 412c3b2fdd0SAndreas Klinger NULL, 413c3b2fdd0SAndreas Klinger }; 414c3b2fdd0SAndreas Klinger 4154214dc18Ssimran singhal static const struct attribute_group hx711_attribute_group = { 416c3b2fdd0SAndreas Klinger .attrs = hx711_attributes, 417c3b2fdd0SAndreas Klinger }; 418c3b2fdd0SAndreas Klinger 419c3b2fdd0SAndreas Klinger static const struct iio_info hx711_iio_info = { 420c3b2fdd0SAndreas Klinger .read_raw = hx711_read_raw, 421c3b2fdd0SAndreas Klinger .write_raw = hx711_write_raw, 422c3b2fdd0SAndreas Klinger .write_raw_get_fmt = hx711_write_raw_get_fmt, 423c3b2fdd0SAndreas Klinger .attrs = &hx711_attribute_group, 424c3b2fdd0SAndreas Klinger }; 425c3b2fdd0SAndreas Klinger 426c3b2fdd0SAndreas Klinger static const struct iio_chan_spec hx711_chan_spec[] = { 427c3b2fdd0SAndreas Klinger { 428c3b2fdd0SAndreas Klinger .type = IIO_VOLTAGE, 429c3b2fdd0SAndreas Klinger .channel = 0, 430c3b2fdd0SAndreas Klinger .indexed = 1, 431c3b2fdd0SAndreas Klinger .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 432c3b2fdd0SAndreas Klinger .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 433d3bf6045SAndreas Klinger .scan_index = 0, 434d3bf6045SAndreas Klinger .scan_type = { 435d3bf6045SAndreas Klinger .sign = 'u', 436d3bf6045SAndreas Klinger .realbits = 24, 437d3bf6045SAndreas Klinger .storagebits = 32, 438d3bf6045SAndreas Klinger .endianness = IIO_CPU, 439d3bf6045SAndreas Klinger }, 440c3b2fdd0SAndreas Klinger }, 441c3b2fdd0SAndreas Klinger { 442c3b2fdd0SAndreas Klinger .type = IIO_VOLTAGE, 443c3b2fdd0SAndreas Klinger .channel = 1, 444c3b2fdd0SAndreas Klinger .indexed = 1, 445c3b2fdd0SAndreas Klinger .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 446c3b2fdd0SAndreas Klinger .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 447d3bf6045SAndreas Klinger .scan_index = 1, 448d3bf6045SAndreas Klinger .scan_type = { 449d3bf6045SAndreas Klinger .sign = 'u', 450d3bf6045SAndreas Klinger .realbits = 24, 451d3bf6045SAndreas Klinger .storagebits = 32, 452d3bf6045SAndreas Klinger .endianness = IIO_CPU, 453c3b2fdd0SAndreas Klinger }, 454d3bf6045SAndreas Klinger }, 455d3bf6045SAndreas Klinger IIO_CHAN_SOFT_TIMESTAMP(2), 456c3b2fdd0SAndreas Klinger }; 457c3b2fdd0SAndreas Klinger 458c3b2fdd0SAndreas Klinger static int hx711_probe(struct platform_device *pdev) 459c3b2fdd0SAndreas Klinger { 460c3b2fdd0SAndreas Klinger struct device *dev = &pdev->dev; 461c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data; 462c3b2fdd0SAndreas Klinger struct iio_dev *indio_dev; 463c3b2fdd0SAndreas Klinger int ret; 464c3b2fdd0SAndreas Klinger int i; 465c3b2fdd0SAndreas Klinger 466c3b2fdd0SAndreas Klinger indio_dev = devm_iio_device_alloc(dev, sizeof(struct hx711_data)); 467c3b2fdd0SAndreas Klinger if (!indio_dev) { 468c3b2fdd0SAndreas Klinger dev_err(dev, "failed to allocate IIO device\n"); 469c3b2fdd0SAndreas Klinger return -ENOMEM; 470c3b2fdd0SAndreas Klinger } 471c3b2fdd0SAndreas Klinger 472c3b2fdd0SAndreas Klinger hx711_data = iio_priv(indio_dev); 473c3b2fdd0SAndreas Klinger hx711_data->dev = dev; 474c3b2fdd0SAndreas Klinger 475c3b2fdd0SAndreas Klinger mutex_init(&hx711_data->lock); 476c3b2fdd0SAndreas Klinger 477c3b2fdd0SAndreas Klinger /* 478c3b2fdd0SAndreas Klinger * PD_SCK stands for power down and serial clock input of HX711 479c3b2fdd0SAndreas Klinger * in the driver it is an output 480c3b2fdd0SAndreas Klinger */ 481c3b2fdd0SAndreas Klinger hx711_data->gpiod_pd_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW); 482c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->gpiod_pd_sck)) { 483c3b2fdd0SAndreas Klinger dev_err(dev, "failed to get sck-gpiod: err=%ld\n", 484c3b2fdd0SAndreas Klinger PTR_ERR(hx711_data->gpiod_pd_sck)); 485c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->gpiod_pd_sck); 486c3b2fdd0SAndreas Klinger } 487c3b2fdd0SAndreas Klinger 488c3b2fdd0SAndreas Klinger /* 489c3b2fdd0SAndreas Klinger * DOUT stands for serial data output of HX711 490c3b2fdd0SAndreas Klinger * for the driver it is an input 491c3b2fdd0SAndreas Klinger */ 492c3b2fdd0SAndreas Klinger hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_IN); 493c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->gpiod_dout)) { 494c3b2fdd0SAndreas Klinger dev_err(dev, "failed to get dout-gpiod: err=%ld\n", 495c3b2fdd0SAndreas Klinger PTR_ERR(hx711_data->gpiod_dout)); 496c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->gpiod_dout); 497c3b2fdd0SAndreas Klinger } 498c3b2fdd0SAndreas Klinger 499c3b2fdd0SAndreas Klinger hx711_data->reg_avdd = devm_regulator_get(dev, "avdd"); 500c3b2fdd0SAndreas Klinger if (IS_ERR(hx711_data->reg_avdd)) 501c3b2fdd0SAndreas Klinger return PTR_ERR(hx711_data->reg_avdd); 502c3b2fdd0SAndreas Klinger 503c3b2fdd0SAndreas Klinger ret = regulator_enable(hx711_data->reg_avdd); 504c3b2fdd0SAndreas Klinger if (ret < 0) 505c3b2fdd0SAndreas Klinger return ret; 506c3b2fdd0SAndreas Klinger 507c3b2fdd0SAndreas Klinger /* 508c3b2fdd0SAndreas Klinger * with 509c3b2fdd0SAndreas Klinger * full scale differential input range: AVDD / GAIN 510c3b2fdd0SAndreas Klinger * full scale output data: 2^24 511c3b2fdd0SAndreas Klinger * we can say: 512c3b2fdd0SAndreas Klinger * AVDD / GAIN = 2^24 513c3b2fdd0SAndreas Klinger * therefore: 514c3b2fdd0SAndreas Klinger * 1 LSB = AVDD / GAIN / 2^24 515c3b2fdd0SAndreas Klinger * AVDD is in uV, but we need 10^-9 mV 516c3b2fdd0SAndreas Klinger * approximately to fit into a 32 bit number: 517c3b2fdd0SAndreas Klinger * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV] 518c3b2fdd0SAndreas Klinger */ 519c3b2fdd0SAndreas Klinger ret = regulator_get_voltage(hx711_data->reg_avdd); 520d3bf6045SAndreas Klinger if (ret < 0) 521d3bf6045SAndreas Klinger goto error_regulator; 522d3bf6045SAndreas Klinger 523c3b2fdd0SAndreas Klinger /* we need 10^-9 mV */ 524c3b2fdd0SAndreas Klinger ret *= 100; 525c3b2fdd0SAndreas Klinger 526c3b2fdd0SAndreas Klinger for (i = 0; i < HX711_GAIN_MAX; i++) 527c3b2fdd0SAndreas Klinger hx711_gain_to_scale[i].scale = 528c3b2fdd0SAndreas Klinger ret / hx711_gain_to_scale[i].gain / 1678; 529c3b2fdd0SAndreas Klinger 530c3b2fdd0SAndreas Klinger hx711_data->gain_set = 128; 531c3b2fdd0SAndreas Klinger hx711_data->gain_chan_a = 128; 532c3b2fdd0SAndreas Klinger 533c3b2fdd0SAndreas Klinger platform_set_drvdata(pdev, indio_dev); 534c3b2fdd0SAndreas Klinger 535c3b2fdd0SAndreas Klinger indio_dev->name = "hx711"; 536c3b2fdd0SAndreas Klinger indio_dev->dev.parent = &pdev->dev; 537c3b2fdd0SAndreas Klinger indio_dev->info = &hx711_iio_info; 538c3b2fdd0SAndreas Klinger indio_dev->modes = INDIO_DIRECT_MODE; 539c3b2fdd0SAndreas Klinger indio_dev->channels = hx711_chan_spec; 540c3b2fdd0SAndreas Klinger indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec); 541c3b2fdd0SAndreas Klinger 542d3bf6045SAndreas Klinger ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time, 543d3bf6045SAndreas Klinger hx711_trigger, NULL); 544d3bf6045SAndreas Klinger if (ret < 0) { 545d3bf6045SAndreas Klinger dev_err(dev, "setup of iio triggered buffer failed\n"); 546d3bf6045SAndreas Klinger goto error_regulator; 547d3bf6045SAndreas Klinger } 548d3bf6045SAndreas Klinger 549c3b2fdd0SAndreas Klinger ret = iio_device_register(indio_dev); 550c3b2fdd0SAndreas Klinger if (ret < 0) { 551c3b2fdd0SAndreas Klinger dev_err(dev, "Couldn't register the device\n"); 552d3bf6045SAndreas Klinger goto error_buffer; 553c3b2fdd0SAndreas Klinger } 554c3b2fdd0SAndreas Klinger 555d3bf6045SAndreas Klinger return 0; 556d3bf6045SAndreas Klinger 557d3bf6045SAndreas Klinger error_buffer: 558d3bf6045SAndreas Klinger iio_triggered_buffer_cleanup(indio_dev); 559d3bf6045SAndreas Klinger 560d3bf6045SAndreas Klinger error_regulator: 561d3bf6045SAndreas Klinger regulator_disable(hx711_data->reg_avdd); 562d3bf6045SAndreas Klinger 563c3b2fdd0SAndreas Klinger return ret; 564c3b2fdd0SAndreas Klinger } 565c3b2fdd0SAndreas Klinger 566c3b2fdd0SAndreas Klinger static int hx711_remove(struct platform_device *pdev) 567c3b2fdd0SAndreas Klinger { 568c3b2fdd0SAndreas Klinger struct hx711_data *hx711_data; 569c3b2fdd0SAndreas Klinger struct iio_dev *indio_dev; 570c3b2fdd0SAndreas Klinger 571c3b2fdd0SAndreas Klinger indio_dev = platform_get_drvdata(pdev); 572c3b2fdd0SAndreas Klinger hx711_data = iio_priv(indio_dev); 573c3b2fdd0SAndreas Klinger 574c3b2fdd0SAndreas Klinger iio_device_unregister(indio_dev); 575c3b2fdd0SAndreas Klinger 576d3bf6045SAndreas Klinger iio_triggered_buffer_cleanup(indio_dev); 577d3bf6045SAndreas Klinger 578c3b2fdd0SAndreas Klinger regulator_disable(hx711_data->reg_avdd); 579c3b2fdd0SAndreas Klinger 580c3b2fdd0SAndreas Klinger return 0; 581c3b2fdd0SAndreas Klinger } 582c3b2fdd0SAndreas Klinger 583c3b2fdd0SAndreas Klinger static const struct of_device_id of_hx711_match[] = { 584c3b2fdd0SAndreas Klinger { .compatible = "avia,hx711", }, 585c3b2fdd0SAndreas Klinger {}, 586c3b2fdd0SAndreas Klinger }; 587c3b2fdd0SAndreas Klinger 588c3b2fdd0SAndreas Klinger MODULE_DEVICE_TABLE(of, of_hx711_match); 589c3b2fdd0SAndreas Klinger 590c3b2fdd0SAndreas Klinger static struct platform_driver hx711_driver = { 591c3b2fdd0SAndreas Klinger .probe = hx711_probe, 592c3b2fdd0SAndreas Klinger .remove = hx711_remove, 593c3b2fdd0SAndreas Klinger .driver = { 594c3b2fdd0SAndreas Klinger .name = "hx711-gpio", 595c3b2fdd0SAndreas Klinger .of_match_table = of_hx711_match, 596c3b2fdd0SAndreas Klinger }, 597c3b2fdd0SAndreas Klinger }; 598c3b2fdd0SAndreas Klinger 599c3b2fdd0SAndreas Klinger module_platform_driver(hx711_driver); 600c3b2fdd0SAndreas Klinger 601c3b2fdd0SAndreas Klinger MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>"); 602c3b2fdd0SAndreas Klinger MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells"); 603c3b2fdd0SAndreas Klinger MODULE_LICENSE("GPL"); 604c3b2fdd0SAndreas Klinger MODULE_ALIAS("platform:hx711-gpio"); 605c3b2fdd0SAndreas Klinger 606