1 // SPDX-License-Identifier: GPL-2.0
5  * Maxim max9611/max9612 high side current sense amplifier with
6  * 12-bit ADC interface.
12  * This driver supports input common-mode voltage, current-sense
16  * Op-amp, analog comparator, and watchdog functionalities are not
48  * max9611 current sense amplifier voltage output:
56  * The complete formula to calculate current sense voltage is:
57  *     (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
71  *     (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
113  * max9611_mux_conf - associate ADC mux configuration with register address
136  * max9611_csa_gain_conf - associate gain multiplier with LSB and
140  * on current sense amplifier path to ADC interface.
141  * Current sense read routine adjusts gain until it gets a meaningful
194  * max9611_read_single() - read a single value from ADC interface
201  * Data are transmitted with big-endian ordering: MSB arrives first.
217 	 * Keep mutex lock held during read-write to avoid mux register  in max9611_read_single()
218 	 * (CTRL1) re-configuration.  in max9611_read_single()
220 	mutex_lock(&max9611->lock);  in max9611_read_single()
221 	ret = i2c_smbus_write_byte_data(max9611->i2c_client,  in max9611_read_single()
224 		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",  in max9611_read_single()
226 		mutex_unlock(&max9611->lock);  in max9611_read_single()
234 	ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);  in max9611_read_single()
236 		dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",  in max9611_read_single()
238 		mutex_unlock(&max9611->lock);  in max9611_read_single()
243 	mutex_unlock(&max9611->lock);  in max9611_read_single()
249  * max9611_read_csa_voltage() - read current sense amplifier output voltage
251  * Current sense amplifier output voltage is read through a configurable
283 	return -EIO;  in max9611_read_csa_voltage()
299 		switch (chan->address) {  in max9611_read_raw()
304 				return -EINVAL;  in max9611_read_raw()
313 				return -EINVAL;  in max9611_read_raw()
329 		switch (chan->address) {  in max9611_read_raw()
346 		switch (chan->address) {  in max9611_read_raw()
349 			 * processed (mV): (raw - offset) * LSB (nV) / 10^6  in max9611_read_raw()
357 				return -EINVAL;  in max9611_read_raw()
361 			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];  in max9611_read_raw()
373 				return -EINVAL;  in max9611_read_raw()
377 			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];  in max9611_read_raw()
380 			*val2 = dev->shunt_resistor_uohm;  in max9611_read_raw()
392 				return -EINVAL;  in max9611_read_raw()
394 			adc_data -= MAX9611_CIM_OFFSET_RAW;  in max9611_read_raw()
401 				return -EINVAL;  in max9611_read_raw()
406 			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];  in max9611_read_raw()
409 			*val2 = dev->shunt_resistor_uohm;  in max9611_read_raw()
417 	return -EINVAL;  in max9611_read_raw()
427 	i = max9611->shunt_resistor_uohm / 1000000;  in max9611_shunt_resistor_show()
428 	r = max9611->shunt_resistor_uohm % 1000000;  in max9611_shunt_resistor_show()
455 	struct i2c_client *client = max9611->i2c_client;  in max9611_init()
459 	if (!i2c_check_functionality(client->adapter,  in max9611_init()
462 		dev_err(max9611->dev,  in max9611_init()
464 		return -EINVAL;  in max9611_init()
477 		dev_err(max9611->dev,  in max9611_init()
480 		return -EIO;  in max9611_init()
484 	ret = i2c_smbus_write_byte_data(max9611->i2c_client,  in max9611_init()
487 		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",  in max9611_init()
492 	ret = i2c_smbus_write_byte_data(max9611->i2c_client,  in max9611_init()
495 		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",  in max9611_init()
513 	const char * const shunt_res_prop = "shunt-resistor-micro-ohms";  in max9611_probe()
516 	struct device *dev = &client->dev;  in max9611_probe()
520 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max9611));  in max9611_probe()
522 		return -ENOMEM;  in max9611_probe()
527 	max9611->dev		= dev;  in max9611_probe()
528 	max9611->i2c_client	= client;  in max9611_probe()
529 	mutex_init(&max9611->lock);  in max9611_probe()
537 	max9611->shunt_resistor_uohm = of_shunt;  in max9611_probe()
543 	indio_dev->name		= device_get_match_data(dev);  in max9611_probe()
544 	indio_dev->modes	= INDIO_DIRECT_MODE;  in max9611_probe()
545 	indio_dev->info		= &indio_info;  in max9611_probe()
546 	indio_dev->channels	= max9611_channels;  in max9611_probe()
547 	indio_dev->num_channels	= ARRAY_SIZE(max9611_channels);  in max9611_probe()
562 MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC");