584 lines
		
	
	
		
			15 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			584 lines
		
	
	
		
			15 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * iio/adc/max9611.c
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 *
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 * Maxim max9611/max9612 high side current sense amplifier with
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 * 12-bit ADC interface.
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 *
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 * Copyright (C) 2017 Jacopo Mondi
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License version 2 as
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 * published by the Free Software Foundation.
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 */
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/*
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 * This driver supports input common-mode voltage, current-sense
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 * amplifier with programmable gains and die temperature reading from
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 * Maxim max9611/max9612.
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 *
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 * Op-amp, analog comparator, and watchdog functionalities are not
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 * supported by this driver.
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 */
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#include <linux/delay.h>
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#include <linux/i2c.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#define DRIVER_NAME			"max9611"
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/* max9611 register addresses */
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#define MAX9611_REG_CSA_DATA		0x00
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#define MAX9611_REG_RS_DATA		0x02
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#define MAX9611_REG_TEMP_DATA		0x08
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#define MAX9611_REG_CTRL1		0x0a
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#define MAX9611_REG_CTRL2		0x0b
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/* max9611 REG1 mux configuration options */
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#define MAX9611_MUX_MASK		GENMASK(3, 0)
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#define MAX9611_MUX_SENSE_1x		0x00
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#define MAX9611_MUX_SENSE_4x		0x01
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#define MAX9611_MUX_SENSE_8x		0x02
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#define MAX9611_INPUT_VOLT		0x03
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#define MAX9611_MUX_TEMP		0x06
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/* max9611 voltage (both csa and input) helper macros */
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#define MAX9611_VOLTAGE_SHIFT		0x04
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#define MAX9611_VOLTAGE_RAW(_r)		((_r) >> MAX9611_VOLTAGE_SHIFT)
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/*
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 * max9611 current sense amplifier voltage output:
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 * LSB and offset values depends on selected gain (1x, 4x, 8x)
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 *
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 * GAIN		LSB (nV)	OFFSET (LSB steps)
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 * 1x		107500		1
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 * 4x		26880		1
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 * 8x		13440		3
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 *
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 * The complete formula to calculate current sense voltage is:
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 *     (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
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 */
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#define MAX9611_CSA_1X_LSB_nV		107500
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#define MAX9611_CSA_4X_LSB_nV		26880
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#define MAX9611_CSA_8X_LSB_nV		13440
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#define MAX9611_CSA_1X_OFFS_RAW		1
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#define MAX9611_CSA_4X_OFFS_RAW		1
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#define MAX9611_CSA_8X_OFFS_RAW		3
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/*
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 * max9611 common input mode (CIM): LSB is 14mV, with 14mV offset at 25 C
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 *
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 * The complete formula to calculate input common voltage is:
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 *     (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
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 */
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#define MAX9611_CIM_LSB_mV		14
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#define MAX9611_CIM_OFFSET_RAW		1
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/*
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 * max9611 temperature reading: LSB is 480 milli degrees Celsius
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 *
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 * The complete formula to calculate temperature is:
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 *     ((adc_read >> 7) * 1000) / (1 / 480 * 1000)
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 */
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#define MAX9611_TEMP_MAX_POS		0x7f80
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#define MAX9611_TEMP_MAX_NEG		0xff80
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#define MAX9611_TEMP_MIN_NEG		0xd980
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#define MAX9611_TEMP_MASK		GENMASK(15, 7)
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#define MAX9611_TEMP_SHIFT		0x07
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#define MAX9611_TEMP_RAW(_r)		((_r) >> MAX9611_TEMP_SHIFT)
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#define MAX9611_TEMP_SCALE_NUM		1000000
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#define MAX9611_TEMP_SCALE_DIV		2083
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struct max9611_dev {
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	struct device *dev;
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	struct i2c_client *i2c_client;
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	struct mutex lock;
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	unsigned int shunt_resistor_uohm;
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};
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enum max9611_conf_ids {
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	CONF_SENSE_1x,
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	CONF_SENSE_4x,
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	CONF_SENSE_8x,
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	CONF_IN_VOLT,
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	CONF_TEMP,
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};
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/**
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 * max9611_mux_conf - associate ADC mux configuration with register address
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 *		      where data shall be read from
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 */
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static const unsigned int max9611_mux_conf[][2] = {
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	/* CONF_SENSE_1x */
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	{ MAX9611_MUX_SENSE_1x, MAX9611_REG_CSA_DATA },
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	/* CONF_SENSE_4x */
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	{ MAX9611_MUX_SENSE_4x, MAX9611_REG_CSA_DATA },
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	/* CONF_SENSE_8x */
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	{ MAX9611_MUX_SENSE_8x, MAX9611_REG_CSA_DATA },
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	/* CONF_IN_VOLT */
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	{ MAX9611_INPUT_VOLT, MAX9611_REG_RS_DATA },
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	/* CONF_TEMP */
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	{ MAX9611_MUX_TEMP, MAX9611_REG_TEMP_DATA },
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};
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enum max9611_csa_gain {
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	CSA_GAIN_1x,
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	CSA_GAIN_4x,
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	CSA_GAIN_8x,
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};
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enum max9611_csa_gain_params {
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	CSA_GAIN_LSB_nV,
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	CSA_GAIN_OFFS_RAW,
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};
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/**
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 * max9611_csa_gain_conf - associate gain multiplier with LSB and
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 *			   offset values.
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 *
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 * Group together parameters associated with configurable gain
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 * on current sense amplifier path to ADC interface.
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 * Current sense read routine adjusts gain until it gets a meaningful
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 * value; use this structure to retrieve the correct LSB and offset values.
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 */
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static const unsigned int max9611_gain_conf[][2] = {
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	{ /* [0] CSA_GAIN_1x */
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		MAX9611_CSA_1X_LSB_nV,
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		MAX9611_CSA_1X_OFFS_RAW,
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	},
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	{ /* [1] CSA_GAIN_4x */
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		MAX9611_CSA_4X_LSB_nV,
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		MAX9611_CSA_4X_OFFS_RAW,
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	},
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	{ /* [2] CSA_GAIN_8x */
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		MAX9611_CSA_8X_LSB_nV,
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		MAX9611_CSA_8X_OFFS_RAW,
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	},
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};
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enum max9611_chan_addrs {
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	MAX9611_CHAN_VOLTAGE_INPUT,
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	MAX9611_CHAN_VOLTAGE_SENSE,
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	MAX9611_CHAN_TEMPERATURE,
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	MAX9611_CHAN_CURRENT_LOAD,
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	MAX9611_CHAN_POWER_LOAD,
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};
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static const struct iio_chan_spec max9611_channels[] = {
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	{
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	  .type			= IIO_TEMP,
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	  .info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |
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				  BIT(IIO_CHAN_INFO_SCALE),
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	  .address		= MAX9611_CHAN_TEMPERATURE,
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	},
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	{
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	  .type			= IIO_VOLTAGE,
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	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
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	  .address		= MAX9611_CHAN_VOLTAGE_SENSE,
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	  .indexed		= 1,
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	  .channel		= 0,
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	},
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	{
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	  .type			= IIO_VOLTAGE,
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	  .info_mask_separate	= BIT(IIO_CHAN_INFO_RAW)   |
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				  BIT(IIO_CHAN_INFO_SCALE) |
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				  BIT(IIO_CHAN_INFO_OFFSET),
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	  .address		= MAX9611_CHAN_VOLTAGE_INPUT,
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	  .indexed		= 1,
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	  .channel		= 1,
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	},
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	{
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	  .type			= IIO_CURRENT,
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	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
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	  .address		= MAX9611_CHAN_CURRENT_LOAD,
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	},
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	{
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	  .type			= IIO_POWER,
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	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
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	  .address		= MAX9611_CHAN_POWER_LOAD
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	},
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};
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/**
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 * max9611_read_single() - read a single value from ADC interface
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 *
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 * Data registers are 16 bit long, spread between two 8 bit registers
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 * with consecutive addresses.
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 * Configure ADC mux first, then read register at address "reg_addr".
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 * The smbus_read_word routine asks for 16 bits and the ADC is kind enough
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 * to return values from "reg_addr" and "reg_addr + 1" consecutively.
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 * Data are transmitted with big-endian ordering: MSB arrives first.
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 *
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 * @max9611: max9611 device
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 * @selector: index for mux and register configuration
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 * @raw_val: the value returned from ADC
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 */
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static int max9611_read_single(struct max9611_dev *max9611,
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			       enum max9611_conf_ids selector,
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			       u16 *raw_val)
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{
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	int ret;
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	u8 mux_conf = max9611_mux_conf[selector][0] & MAX9611_MUX_MASK;
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	u8 reg_addr = max9611_mux_conf[selector][1];
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	/*
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	 * Keep mutex lock held during read-write to avoid mux register
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	 * (CTRL1) re-configuration.
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	 */
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	mutex_lock(&max9611->lock);
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	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
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					MAX9611_REG_CTRL1, mux_conf);
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	if (ret) {
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		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
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			MAX9611_REG_CTRL1, mux_conf);
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		mutex_unlock(&max9611->lock);
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		return ret;
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	}
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	/*
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	 * need a delay here to make register configuration
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	 * stabilize. 1 msec at least, from empirical testing.
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	 */
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	usleep_range(1000, 2000);
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	ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);
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	if (ret < 0) {
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		dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",
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			reg_addr);
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		mutex_unlock(&max9611->lock);
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		return ret;
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	}
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	*raw_val = ret;
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	mutex_unlock(&max9611->lock);
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	return 0;
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}
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/**
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 * max9611_read_csa_voltage() - read current sense amplifier output voltage
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 *
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 * Current sense amplifier output voltage is read through a configurable
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 * 1x, 4x or 8x gain.
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 * Start with plain 1x gain, and adjust gain control properly until a
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 * meaningful value is read from ADC output.
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 *
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 * @max9611: max9611 device
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 * @adc_raw: raw value read from ADC output
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 * @csa_gain: gain configuration option selector
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 */
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static int max9611_read_csa_voltage(struct max9611_dev *max9611,
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				    u16 *adc_raw,
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				    enum max9611_csa_gain *csa_gain)
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{
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	enum max9611_conf_ids gain_selectors[] = {
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		CONF_SENSE_1x,
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		CONF_SENSE_4x,
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		CONF_SENSE_8x
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	};
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	unsigned int i;
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	int ret;
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	for (i = 0; i < ARRAY_SIZE(gain_selectors); ++i) {
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		ret = max9611_read_single(max9611, gain_selectors[i], adc_raw);
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		if (ret)
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			return ret;
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		if (*adc_raw > 0) {
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			*csa_gain = (enum max9611_csa_gain)gain_selectors[i];
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			return 0;
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		}
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	}
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	return -EIO;
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}
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static int max9611_read_raw(struct iio_dev *indio_dev,
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			    struct iio_chan_spec const *chan,
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			    int *val, int *val2, long mask)
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{
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	struct max9611_dev *dev = iio_priv(indio_dev);
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	enum max9611_csa_gain gain_selector;
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	const unsigned int *csa_gain;
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	u16 adc_data;
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	int ret;
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	switch (mask) {
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	case IIO_CHAN_INFO_RAW:
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		switch (chan->address) {
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		case MAX9611_CHAN_TEMPERATURE:
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			ret = max9611_read_single(dev, CONF_TEMP,
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						  &adc_data);
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			if (ret)
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				return -EINVAL;
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			*val = MAX9611_TEMP_RAW(adc_data);
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			return IIO_VAL_INT;
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		case MAX9611_CHAN_VOLTAGE_INPUT:
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			ret = max9611_read_single(dev, CONF_IN_VOLT,
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						  &adc_data);
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			if (ret)
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				return -EINVAL;
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			*val = MAX9611_VOLTAGE_RAW(adc_data);
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			return IIO_VAL_INT;
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		}
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		break;
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	case IIO_CHAN_INFO_OFFSET:
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		/* MAX9611_CHAN_VOLTAGE_INPUT */
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		*val = MAX9611_CIM_OFFSET_RAW;
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		return IIO_VAL_INT;
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	case IIO_CHAN_INFO_SCALE:
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		switch (chan->address) {
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		case MAX9611_CHAN_TEMPERATURE:
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			*val = MAX9611_TEMP_SCALE_NUM;
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			*val2 = MAX9611_TEMP_SCALE_DIV;
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			return IIO_VAL_FRACTIONAL;
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		case MAX9611_CHAN_VOLTAGE_INPUT:
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			*val = MAX9611_CIM_LSB_mV;
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			return IIO_VAL_INT;
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		}
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		break;
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	case IIO_CHAN_INFO_PROCESSED:
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						|
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		switch (chan->address) {
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		case MAX9611_CHAN_VOLTAGE_SENSE:
 | 
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			/*
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			 * processed (mV): (raw - offset) * LSB (nV) / 10^6
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			 *
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			 * Even if max9611 can output raw csa voltage readings,
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			 * use a produced value as scale depends on gain.
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						|
			 */
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			ret = max9611_read_csa_voltage(dev, &adc_data,
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						       &gain_selector);
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			if (ret)
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				return -EINVAL;
 | 
						|
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			csa_gain = max9611_gain_conf[gain_selector];
 | 
						|
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			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
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			*val = MAX9611_VOLTAGE_RAW(adc_data) *
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			       csa_gain[CSA_GAIN_LSB_nV];
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			*val2 = 1000000;
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						|
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			return IIO_VAL_FRACTIONAL;
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						|
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						|
		case MAX9611_CHAN_CURRENT_LOAD:
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			/* processed (mA): Vcsa (nV) / Rshunt (uOhm)  */
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			ret = max9611_read_csa_voltage(dev, &adc_data,
 | 
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						       &gain_selector);
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			if (ret)
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				return -EINVAL;
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			csa_gain = max9611_gain_conf[gain_selector];
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			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
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			*val = MAX9611_VOLTAGE_RAW(adc_data) *
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			       csa_gain[CSA_GAIN_LSB_nV];
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			*val2 = dev->shunt_resistor_uohm;
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						|
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			return IIO_VAL_FRACTIONAL;
 | 
						|
 | 
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		case MAX9611_CHAN_POWER_LOAD:
 | 
						|
			/*
 | 
						|
			 * processed (mW): Vin (mV) * Vcsa (uV) /
 | 
						|
			 *		   Rshunt (uOhm)
 | 
						|
			 */
 | 
						|
			ret = max9611_read_single(dev, CONF_IN_VOLT,
 | 
						|
						  &adc_data);
 | 
						|
			if (ret)
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						|
				return -EINVAL;
 | 
						|
 | 
						|
			adc_data -= MAX9611_CIM_OFFSET_RAW;
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						|
			*val = MAX9611_VOLTAGE_RAW(adc_data) *
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			       MAX9611_CIM_LSB_mV;
 | 
						|
 | 
						|
			ret = max9611_read_csa_voltage(dev, &adc_data,
 | 
						|
						       &gain_selector);
 | 
						|
			if (ret)
 | 
						|
				return -EINVAL;
 | 
						|
 | 
						|
			csa_gain = max9611_gain_conf[gain_selector];
 | 
						|
 | 
						|
			/* divide by 10^3 here to avoid 32bit overflow */
 | 
						|
			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
 | 
						|
			*val *= MAX9611_VOLTAGE_RAW(adc_data) *
 | 
						|
				csa_gain[CSA_GAIN_LSB_nV] / 1000;
 | 
						|
			*val2 = dev->shunt_resistor_uohm;
 | 
						|
 | 
						|
			return IIO_VAL_FRACTIONAL;
 | 
						|
		}
 | 
						|
 | 
						|
		break;
 | 
						|
	}
 | 
						|
 | 
						|
	return -EINVAL;
 | 
						|
}
 | 
						|
 | 
						|
static ssize_t max9611_shunt_resistor_show(struct device *dev,
 | 
						|
					   struct device_attribute *attr,
 | 
						|
					   char *buf)
 | 
						|
{
 | 
						|
	struct max9611_dev *max9611 = iio_priv(dev_to_iio_dev(dev));
 | 
						|
	unsigned int i, r;
 | 
						|
 | 
						|
	i = max9611->shunt_resistor_uohm / 1000000;
 | 
						|
	r = max9611->shunt_resistor_uohm % 1000000;
 | 
						|
 | 
						|
	return sprintf(buf, "%u.%06u\n", i, r);
 | 
						|
}
 | 
						|
 | 
						|
static IIO_DEVICE_ATTR(in_power_shunt_resistor, 0444,
 | 
						|
		       max9611_shunt_resistor_show, NULL, 0);
 | 
						|
static IIO_DEVICE_ATTR(in_current_shunt_resistor, 0444,
 | 
						|
		       max9611_shunt_resistor_show, NULL, 0);
 | 
						|
 | 
						|
static struct attribute *max9611_attributes[] = {
 | 
						|
	&iio_dev_attr_in_power_shunt_resistor.dev_attr.attr,
 | 
						|
	&iio_dev_attr_in_current_shunt_resistor.dev_attr.attr,
 | 
						|
	NULL,
 | 
						|
};
 | 
						|
 | 
						|
static const struct attribute_group max9611_attribute_group = {
 | 
						|
	.attrs = max9611_attributes,
 | 
						|
};
 | 
						|
 | 
						|
static const struct iio_info indio_info = {
 | 
						|
	.read_raw	= max9611_read_raw,
 | 
						|
	.attrs		= &max9611_attribute_group,
 | 
						|
};
 | 
						|
 | 
						|
static int max9611_init(struct max9611_dev *max9611)
 | 
						|
{
 | 
						|
	struct i2c_client *client = max9611->i2c_client;
 | 
						|
	u16 regval;
 | 
						|
	int ret;
 | 
						|
 | 
						|
	if (!i2c_check_functionality(client->adapter,
 | 
						|
				     I2C_FUNC_SMBUS_WRITE_BYTE	|
 | 
						|
				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
 | 
						|
		dev_err(max9611->dev,
 | 
						|
			"I2c adapter does not support smbus write_byte or read_word functionalities: aborting probe.\n");
 | 
						|
		return -EINVAL;
 | 
						|
	}
 | 
						|
 | 
						|
	/* Make sure die temperature is in range to test communications. */
 | 
						|
	ret = max9611_read_single(max9611, CONF_TEMP, ®val);
 | 
						|
	if (ret)
 | 
						|
		return ret;
 | 
						|
 | 
						|
	regval &= MAX9611_TEMP_MASK;
 | 
						|
 | 
						|
	if ((regval > MAX9611_TEMP_MAX_POS &&
 | 
						|
	     regval < MAX9611_TEMP_MIN_NEG) ||
 | 
						|
	     regval > MAX9611_TEMP_MAX_NEG) {
 | 
						|
		dev_err(max9611->dev,
 | 
						|
			"Invalid value received from ADC 0x%4x: aborting\n",
 | 
						|
			regval);
 | 
						|
		return -EIO;
 | 
						|
	}
 | 
						|
 | 
						|
	/* Mux shall be zeroed back before applying other configurations */
 | 
						|
	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
 | 
						|
					MAX9611_REG_CTRL1, 0);
 | 
						|
	if (ret) {
 | 
						|
		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
 | 
						|
			MAX9611_REG_CTRL1, 0);
 | 
						|
		return ret;
 | 
						|
	}
 | 
						|
 | 
						|
	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
 | 
						|
					MAX9611_REG_CTRL2, 0);
 | 
						|
	if (ret) {
 | 
						|
		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
 | 
						|
			MAX9611_REG_CTRL2, 0);
 | 
						|
		return ret;
 | 
						|
	}
 | 
						|
	usleep_range(1000, 2000);
 | 
						|
 | 
						|
	return 0;
 | 
						|
}
 | 
						|
 | 
						|
static const struct of_device_id max9611_of_table[] = {
 | 
						|
	{.compatible = "maxim,max9611", .data = "max9611"},
 | 
						|
	{.compatible = "maxim,max9612", .data = "max9612"},
 | 
						|
	{ },
 | 
						|
};
 | 
						|
 | 
						|
MODULE_DEVICE_TABLE(of, max9611_of_table);
 | 
						|
static int max9611_probe(struct i2c_client *client,
 | 
						|
			 const struct i2c_device_id *id)
 | 
						|
{
 | 
						|
	const char * const shunt_res_prop = "shunt-resistor-micro-ohms";
 | 
						|
	const struct device_node *of_node = client->dev.of_node;
 | 
						|
	const struct of_device_id *of_id =
 | 
						|
		of_match_device(max9611_of_table, &client->dev);
 | 
						|
	struct max9611_dev *max9611;
 | 
						|
	struct iio_dev *indio_dev;
 | 
						|
	unsigned int of_shunt;
 | 
						|
	int ret;
 | 
						|
 | 
						|
	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max9611));
 | 
						|
	if (!indio_dev)
 | 
						|
		return -ENOMEM;
 | 
						|
 | 
						|
	i2c_set_clientdata(client, indio_dev);
 | 
						|
 | 
						|
	max9611			= iio_priv(indio_dev);
 | 
						|
	max9611->dev		= &client->dev;
 | 
						|
	max9611->i2c_client	= client;
 | 
						|
	mutex_init(&max9611->lock);
 | 
						|
 | 
						|
	ret = of_property_read_u32(of_node, shunt_res_prop, &of_shunt);
 | 
						|
	if (ret) {
 | 
						|
		dev_err(&client->dev,
 | 
						|
			"Missing %s property for %pOF node\n",
 | 
						|
			shunt_res_prop, of_node);
 | 
						|
		return ret;
 | 
						|
	}
 | 
						|
	max9611->shunt_resistor_uohm = of_shunt;
 | 
						|
 | 
						|
	ret = max9611_init(max9611);
 | 
						|
	if (ret)
 | 
						|
		return ret;
 | 
						|
 | 
						|
	indio_dev->dev.parent	= &client->dev;
 | 
						|
	indio_dev->dev.of_node	= client->dev.of_node;
 | 
						|
	indio_dev->name		= of_id->data;
 | 
						|
	indio_dev->modes	= INDIO_DIRECT_MODE;
 | 
						|
	indio_dev->info		= &indio_info;
 | 
						|
	indio_dev->channels	= max9611_channels;
 | 
						|
	indio_dev->num_channels	= ARRAY_SIZE(max9611_channels);
 | 
						|
 | 
						|
	return devm_iio_device_register(&client->dev, indio_dev);
 | 
						|
}
 | 
						|
 | 
						|
static struct i2c_driver max9611_driver = {
 | 
						|
	.driver = {
 | 
						|
		   .name = DRIVER_NAME,
 | 
						|
		   .of_match_table = max9611_of_table,
 | 
						|
	},
 | 
						|
	.probe = max9611_probe,
 | 
						|
};
 | 
						|
module_i2c_driver(max9611_driver);
 | 
						|
 | 
						|
MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
 | 
						|
MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC");
 | 
						|
MODULE_LICENSE("GPL v2");
 |