drivers/hwmon/gsc-hwmon.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Driver for Gateworks System Controller Hardware Monitor module
  *
  * Copyright (C) 2020 Gateworks Corporation
  */
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/mfd/gsc.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>

 #include <linux/platform_data/gsc_hwmon.h>

 #define GSC_HWMON_MAX_TEMP_CH	16
 #define GSC_HWMON_MAX_IN_CH	16

 #define GSC_HWMON_RESOLUTION	12
 #define GSC_HWMON_VREF		2500

 struct gsc_hwmon_data {
 	struct gsc_dev *gsc;
 	struct gsc_hwmon_platform_data *pdata;
 	struct regmap *regmap;
 	const struct gsc_hwmon_channel *temp_ch[GSC_HWMON_MAX_TEMP_CH];
 	const struct gsc_hwmon_channel *in_ch[GSC_HWMON_MAX_IN_CH];
 	u32 temp_config[GSC_HWMON_MAX_TEMP_CH + 1];
 	u32 in_config[GSC_HWMON_MAX_IN_CH + 1];
 	struct hwmon_channel_info temp_info;
 	struct hwmon_channel_info in_info;
 	const struct hwmon_channel_info *info[3];
 	struct hwmon_chip_info chip;
 };

 static struct regmap_bus gsc_hwmon_regmap_bus = {
 	.reg_read = gsc_read,
 	.reg_write = gsc_write,
 };

 static const struct regmap_config gsc_hwmon_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.cache_type = REGCACHE_NONE,
 };

 static ssize_t pwm_auto_point_temp_show(struct device *dev,
 					struct device_attribute *devattr,
 					char *buf)
 {
 	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	u8 reg = hwmon->pdata->fan_base + (2 * attr->index);
 	u8 regs[2];
 	int ret;

 	ret = regmap_bulk_read(hwmon->regmap, reg, regs, 2);
 	if (ret)
 		return ret;

 	ret = regs[0] | regs[1] << 8;
 	return sprintf(buf, "%d\n", ret * 10);
 }

 static ssize_t pwm_auto_point_temp_store(struct device *dev,
 					 struct device_attribute *devattr,
 					 const char *buf, size_t count)
 {
 	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	u8 reg = hwmon->pdata->fan_base + (2 * attr->index);
 	u8 regs[2];
 	long temp;
 	int err;

 	if (kstrtol(buf, 10, &temp))
 		return -EINVAL;

 	temp = clamp_val(temp, 0, 10000);
 	temp = DIV_ROUND_CLOSEST(temp, 10);

 	regs[0] = temp & 0xff;
 	regs[1] = (temp >> 8) & 0xff;
 	err = regmap_bulk_write(hwmon->regmap, reg, regs, 2);
 	if (err)
 		return err;

 	return count;
 }

 static ssize_t pwm_auto_point_pwm_show(struct device *dev,
 				       struct device_attribute *devattr,
 				       char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

 	return sprintf(buf, "%d\n", 255 * (50 + (attr->index * 10)) / 100);
 }

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point1_pwm, pwm_auto_point_pwm, 0);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point1_temp, pwm_auto_point_temp, 0);

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point2_pwm, pwm_auto_point_pwm, 1);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point2_temp, pwm_auto_point_temp, 1);

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point3_pwm, pwm_auto_point_pwm, 2);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point3_temp, pwm_auto_point_temp, 2);

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point4_pwm, pwm_auto_point_pwm, 3);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point4_temp, pwm_auto_point_temp, 3);

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point5_pwm, pwm_auto_point_pwm, 4);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point5_temp, pwm_auto_point_temp, 4);

 static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point6_pwm, pwm_auto_point_pwm, 5);
 static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point6_temp, pwm_auto_point_temp, 5);

 static struct attribute *gsc_hwmon_attributes[] = {
 	&sensor_dev_attr_pwm1_auto_point1_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point1_temp.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point2_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point2_temp.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point3_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point3_temp.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point4_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point4_temp.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point5_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point5_temp.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point6_pwm.dev_attr.attr,
 	&sensor_dev_attr_pwm1_auto_point6_temp.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group gsc_hwmon_group = {
 	.attrs = gsc_hwmon_attributes,
 };
 __ATTRIBUTE_GROUPS(gsc_hwmon);

 static int
 gsc_hwmon_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 	       int channel, long *val)
 {
 	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
 	const struct gsc_hwmon_channel *ch;
 	int sz, ret;
 	long tmp;
 	u8 buf[3];

 	switch (type) {
 	case hwmon_in:
 		ch = hwmon->in_ch[channel];
 		break;
 	case hwmon_temp:
 		ch = hwmon->temp_ch[channel];
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	sz = (ch->mode == mode_voltage_24bit) ? 3 : 2;
 	ret = regmap_bulk_read(hwmon->regmap, ch->reg, buf, sz);
 	if (ret)
 		return ret;

 	tmp = 0;
 	while (sz-- > 0)
 		tmp |= (buf[sz] << (8 * sz));

 	switch (ch->mode) {
 	case mode_temperature:
 		if (tmp > 0x8000)
 			tmp -= 0xffff;
 		tmp *= 100; /* convert to millidegrees celsius */
 		break;
 	case mode_voltage_raw:
 		tmp = clamp_val(tmp, 0, BIT(GSC_HWMON_RESOLUTION));
 		/* scale based on ref voltage and ADC resolution */
 		tmp *= GSC_HWMON_VREF;
 		tmp >>= GSC_HWMON_RESOLUTION;
 		/* scale based on optional voltage divider */
 		if (ch->vdiv[0] && ch->vdiv[1]) {
 			tmp *= (ch->vdiv[0] + ch->vdiv[1]);
 			tmp /= ch->vdiv[1];
 		}
 		/* adjust by uV offset */
 		tmp += ch->mvoffset;
 		break;
 	case mode_voltage_24bit:
 	case mode_voltage_16bit:
 		/* no adjustment needed */
 		break;
 	}

 	*val = tmp;

 	return 0;
 }

 static int
 gsc_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
 		      u32 attr, int channel, const char **buf)
 {
 	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);

 	switch (type) {
 	case hwmon_in:
 		*buf = hwmon->in_ch[channel]->name;
 		break;
 	case hwmon_temp:
 		*buf = hwmon->temp_ch[channel]->name;
 		break;
 	default:
 		return -ENOTSUPP;
 	}

 	return 0;
 }

 static umode_t
 gsc_hwmon_is_visible(const void *_data, enum hwmon_sensor_types type, u32 attr,
 		     int ch)
 {
 	return 0444;
 }

 static const struct hwmon_ops gsc_hwmon_ops = {
 	.is_visible = gsc_hwmon_is_visible,
 	.read = gsc_hwmon_read,
 	.read_string = gsc_hwmon_read_string,
 };

 static struct gsc_hwmon_platform_data *
 gsc_hwmon_get_devtree_pdata(struct device *dev)
 {
 	struct gsc_hwmon_platform_data *pdata;
 	struct gsc_hwmon_channel *ch;
 	struct fwnode_handle *child;
 	struct device_node *fan;
 	int nchannels;

 	nchannels = device_get_child_node_count(dev);
 	if (nchannels == 0)
 		return ERR_PTR(-ENODEV);

 	pdata = devm_kzalloc(dev,
 			     sizeof(*pdata) + nchannels * sizeof(*ch),
 			     GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);
 	ch = (struct gsc_hwmon_channel *)(pdata + 1);
 	pdata->channels = ch;
 	pdata->nchannels = nchannels;

 	/* fan controller base address */
 	fan = of_find_compatible_node(dev->parent->of_node, NULL, "gw,gsc-fan");
 	if (fan && of_property_read_u32(fan, "reg", &pdata->fan_base)) {
 		dev_err(dev, "fan node without base\n");
 		return ERR_PTR(-EINVAL);
 	}

 	/* allocate structures for channels and count instances of each type */
 	device_for_each_child_node(dev, child) {
 		if (fwnode_property_read_string(child, "label", &ch->name)) {
 			dev_err(dev, "channel without label\n");
 			fwnode_handle_put(child);
 			return ERR_PTR(-EINVAL);
 		}
 		if (fwnode_property_read_u32(child, "reg", &ch->reg)) {
 			dev_err(dev, "channel without reg\n");
 			fwnode_handle_put(child);
 			return ERR_PTR(-EINVAL);
 		}
 		if (fwnode_property_read_u32(child, "gw,mode", &ch->mode)) {
 			dev_err(dev, "channel without mode\n");
 			fwnode_handle_put(child);
 			return ERR_PTR(-EINVAL);
 		}
 		if (ch->mode > mode_max) {
 			dev_err(dev, "invalid channel mode\n");
 			fwnode_handle_put(child);
 			return ERR_PTR(-EINVAL);
 		}

 		if (!fwnode_property_read_u32(child,
 					      "gw,voltage-offset-microvolt",
 					      &ch->mvoffset))
 			ch->mvoffset /= 1000;
 		fwnode_property_read_u32_array(child,
 					       "gw,voltage-divider-ohms",
 					       ch->vdiv, ARRAY_SIZE(ch->vdiv));
 		ch++;
 	}

 	return pdata;
 }

 static int gsc_hwmon_probe(struct platform_device *pdev)
 {
 	struct gsc_dev *gsc = dev_get_drvdata(pdev->dev.parent);
 	struct device *dev = &pdev->dev;
 	struct device *hwmon_dev;
 	struct gsc_hwmon_platform_data *pdata = dev_get_platdata(dev);
 	struct gsc_hwmon_data *hwmon;
 	const struct attribute_group **groups;
 	int i, i_in, i_temp;

 	if (!pdata) {
 		pdata = gsc_hwmon_get_devtree_pdata(dev);
 		if (IS_ERR(pdata))
 			return PTR_ERR(pdata);
 	}

 	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
 	if (!hwmon)
 		return -ENOMEM;
 	hwmon->gsc = gsc;
 	hwmon->pdata = pdata;

 	hwmon->regmap = devm_regmap_init(dev, &gsc_hwmon_regmap_bus,
 					 gsc->i2c_hwmon,
 					 &gsc_hwmon_regmap_config);
 	if (IS_ERR(hwmon->regmap))
 		return PTR_ERR(hwmon->regmap);

 	for (i = 0, i_in = 0, i_temp = 0; i < hwmon->pdata->nchannels; i++) {
 		const struct gsc_hwmon_channel *ch = &pdata->channels[i];

 		switch (ch->mode) {
 		case mode_temperature:
 			if (i_temp == GSC_HWMON_MAX_TEMP_CH) {
 				dev_err(gsc->dev, "too many temp channels\n");
 				return -EINVAL;
 			}
 			hwmon->temp_ch[i_temp] = ch;
 			hwmon->temp_config[i_temp] = HWMON_T_INPUT |
 						     HWMON_T_LABEL;
 			i_temp++;
 			break;
 		case mode_voltage_24bit:
 		case mode_voltage_16bit:
 		case mode_voltage_raw:
 			if (i_in == GSC_HWMON_MAX_IN_CH) {
 				dev_err(gsc->dev, "too many input channels\n");
 				return -EINVAL;
 			}
 			hwmon->in_ch[i_in] = ch;
 			hwmon->in_config[i_in] =
 				HWMON_I_INPUT | HWMON_I_LABEL;
 			i_in++;
 			break;
 		default:
 			dev_err(gsc->dev, "invalid mode: %d\n", ch->mode);
 			return -EINVAL;
 		}
 	}

 	/* setup config structures */
 	hwmon->chip.ops = &gsc_hwmon_ops;
 	hwmon->chip.info = hwmon->info;
 	hwmon->info[0] = &hwmon->temp_info;
 	hwmon->info[1] = &hwmon->in_info;
 	hwmon->temp_info.type = hwmon_temp;
 	hwmon->temp_info.config = hwmon->temp_config;
 	hwmon->in_info.type = hwmon_in;
 	hwmon->in_info.config = hwmon->in_config;

 	groups = pdata->fan_base ? gsc_hwmon_groups : NULL;
 	hwmon_dev = devm_hwmon_device_register_with_info(dev,
 							 KBUILD_MODNAME, hwmon,
 							 &hwmon->chip, groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct of_device_id gsc_hwmon_of_match[] = {
 	{ .compatible = "gw,gsc-adc", },
 	{}
 };

 static struct platform_driver gsc_hwmon_driver = {
 	.driver = {
 		.name = "gsc-hwmon",
 		.of_match_table = gsc_hwmon_of_match,
 	},
 	.probe = gsc_hwmon_probe,
 };

 module_platform_driver(gsc_hwmon_driver);

 MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
 MODULE_DESCRIPTION("GSC hardware monitor driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Driver for Gateworks System Controller Hardware Monitor module
	*
	* Copyright (C) 2020 Gateworks Corporation
	*/
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/mfd/gsc.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>

	#include <linux/platform_data/gsc_hwmon.h>

	#define GSC_HWMON_MAX_TEMP_CH 16
	#define GSC_HWMON_MAX_IN_CH 16

	#define GSC_HWMON_RESOLUTION 12
	#define GSC_HWMON_VREF 2500

	struct gsc_hwmon_data {
	struct gsc_dev *gsc;
	struct gsc_hwmon_platform_data *pdata;
	struct regmap *regmap;
	const struct gsc_hwmon_channel *temp_ch[GSC_HWMON_MAX_TEMP_CH];
	const struct gsc_hwmon_channel *in_ch[GSC_HWMON_MAX_IN_CH];
	u32 temp_config[GSC_HWMON_MAX_TEMP_CH + 1];
	u32 in_config[GSC_HWMON_MAX_IN_CH + 1];
	struct hwmon_channel_info temp_info;
	struct hwmon_channel_info in_info;
	const struct hwmon_channel_info *info[3];
	struct hwmon_chip_info chip;
	};

	static struct regmap_bus gsc_hwmon_regmap_bus = {
	.reg_read = gsc_read,
	.reg_write = gsc_write,
	};

	static const struct regmap_config gsc_hwmon_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.cache_type = REGCACHE_NONE,
	};

	static ssize_t pwm_auto_point_temp_show(struct device *dev,
	struct device_attribute *devattr,
	char *buf)
	{
	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	u8 reg = hwmon->pdata->fan_base + (2 * attr->index);
	u8 regs[2];
	int ret;

	ret = regmap_bulk_read(hwmon->regmap, reg, regs, 2);
	if (ret)
	return ret;

	ret = regs[0] \| regs[1] << 8;
	return sprintf(buf, "%d\n", ret * 10);
	}

	static ssize_t pwm_auto_point_temp_store(struct device *dev,
	struct device_attribute *devattr,
	const char *buf, size_t count)
	{
	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	u8 reg = hwmon->pdata->fan_base + (2 * attr->index);
	u8 regs[2];
	long temp;
	int err;

	if (kstrtol(buf, 10, &temp))
	return -EINVAL;

	temp = clamp_val(temp, 0, 10000);
	temp = DIV_ROUND_CLOSEST(temp, 10);

	regs[0] = temp & 0xff;
	regs[1] = (temp >> 8) & 0xff;
	err = regmap_bulk_write(hwmon->regmap, reg, regs, 2);
	if (err)
	return err;

	return count;
	}

	static ssize_t pwm_auto_point_pwm_show(struct device *dev,
	struct device_attribute *devattr,
	char *buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

	return sprintf(buf, "%d\n", 255 * (50 + (attr->index * 10)) / 100);
	}

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point1_pwm, pwm_auto_point_pwm, 0);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point1_temp, pwm_auto_point_temp, 0);

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point2_pwm, pwm_auto_point_pwm, 1);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point2_temp, pwm_auto_point_temp, 1);

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point3_pwm, pwm_auto_point_pwm, 2);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point3_temp, pwm_auto_point_temp, 2);

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point4_pwm, pwm_auto_point_pwm, 3);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point4_temp, pwm_auto_point_temp, 3);

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point5_pwm, pwm_auto_point_pwm, 4);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point5_temp, pwm_auto_point_temp, 4);

	static SENSOR_DEVICE_ATTR_RO(pwm1_auto_point6_pwm, pwm_auto_point_pwm, 5);
	static SENSOR_DEVICE_ATTR_RW(pwm1_auto_point6_temp, pwm_auto_point_temp, 5);

	static struct attribute *gsc_hwmon_attributes[] = {
	&sensor_dev_attr_pwm1_auto_point1_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point1_temp.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point2_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point2_temp.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point3_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point3_temp.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point4_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point4_temp.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point5_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point5_temp.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point6_pwm.dev_attr.attr,
	&sensor_dev_attr_pwm1_auto_point6_temp.dev_attr.attr,
	NULL
	};

	static const struct attribute_group gsc_hwmon_group = {
	.attrs = gsc_hwmon_attributes,
	};
	__ATTRIBUTE_GROUPS(gsc_hwmon);

	static int
	gsc_hwmon_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	int channel, long *val)
	{
	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
	const struct gsc_hwmon_channel *ch;
	int sz, ret;
	long tmp;
	u8 buf[3];

	switch (type) {
	case hwmon_in:
	ch = hwmon->in_ch[channel];
	break;
	case hwmon_temp:
	ch = hwmon->temp_ch[channel];
	break;
	default:
	return -EOPNOTSUPP;
	}

	sz = (ch->mode == mode_voltage_24bit) ? 3 : 2;
	ret = regmap_bulk_read(hwmon->regmap, ch->reg, buf, sz);
	if (ret)
	return ret;

	tmp = 0;
	while (sz-- > 0)
	tmp \|= (buf[sz] << (8 * sz));

	switch (ch->mode) {
	case mode_temperature:
	if (tmp > 0x8000)
	tmp -= 0xffff;
	tmp = 100; / convert to millidegrees celsius */
	break;
	case mode_voltage_raw:
	tmp = clamp_val(tmp, 0, BIT(GSC_HWMON_RESOLUTION));
	/* scale based on ref voltage and ADC resolution */
	tmp *= GSC_HWMON_VREF;
	tmp >>= GSC_HWMON_RESOLUTION;
	/* scale based on optional voltage divider */
	if (ch->vdiv[0] && ch->vdiv[1]) {
	tmp *= (ch->vdiv[0] + ch->vdiv[1]);
	tmp /= ch->vdiv[1];
	}
	/* adjust by uV offset */
	tmp += ch->mvoffset;
	break;
	case mode_voltage_24bit:
	case mode_voltage_16bit:
	/* no adjustment needed */
	break;
	}

	*val = tmp;

	return 0;
	}

	static int
	gsc_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, const char **buf)
	{
	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);

	switch (type) {
	case hwmon_in:
	*buf = hwmon->in_ch[channel]->name;
	break;
	case hwmon_temp:
	*buf = hwmon->temp_ch[channel]->name;
	break;
	default:
	return -ENOTSUPP;
	}

	return 0;
	}

	static umode_t
	gsc_hwmon_is_visible(const void *_data, enum hwmon_sensor_types type, u32 attr,
	int ch)
	{
	return 0444;
	}

	static const struct hwmon_ops gsc_hwmon_ops = {
	.is_visible = gsc_hwmon_is_visible,
	.read = gsc_hwmon_read,
	.read_string = gsc_hwmon_read_string,
	};

	static struct gsc_hwmon_platform_data *
	gsc_hwmon_get_devtree_pdata(struct device *dev)
	{
	struct gsc_hwmon_platform_data *pdata;
	struct gsc_hwmon_channel *ch;
	struct fwnode_handle *child;
	struct device_node *fan;
	int nchannels;

	nchannels = device_get_child_node_count(dev);
	if (nchannels == 0)
	return ERR_PTR(-ENODEV);

	pdata = devm_kzalloc(dev,
	sizeof(pdata) + nchannels sizeof(*ch),
	GFP_KERNEL);
	if (!pdata)
	return ERR_PTR(-ENOMEM);
	ch = (struct gsc_hwmon_channel *)(pdata + 1);
	pdata->channels = ch;
	pdata->nchannels = nchannels;

	/* fan controller base address */
	fan = of_find_compatible_node(dev->parent->of_node, NULL, "gw,gsc-fan");
	if (fan && of_property_read_u32(fan, "reg", &pdata->fan_base)) {
	dev_err(dev, "fan node without base\n");
	return ERR_PTR(-EINVAL);
	}

	/* allocate structures for channels and count instances of each type */
	device_for_each_child_node(dev, child) {
	if (fwnode_property_read_string(child, "label", &ch->name)) {
	dev_err(dev, "channel without label\n");
	fwnode_handle_put(child);
	return ERR_PTR(-EINVAL);
	}
	if (fwnode_property_read_u32(child, "reg", &ch->reg)) {
	dev_err(dev, "channel without reg\n");
	fwnode_handle_put(child);
	return ERR_PTR(-EINVAL);
	}
	if (fwnode_property_read_u32(child, "gw,mode", &ch->mode)) {
	dev_err(dev, "channel without mode\n");
	fwnode_handle_put(child);
	return ERR_PTR(-EINVAL);
	}
	if (ch->mode > mode_max) {
	dev_err(dev, "invalid channel mode\n");
	fwnode_handle_put(child);
	return ERR_PTR(-EINVAL);
	}

	if (!fwnode_property_read_u32(child,
	"gw,voltage-offset-microvolt",
	&ch->mvoffset))
	ch->mvoffset /= 1000;
	fwnode_property_read_u32_array(child,
	"gw,voltage-divider-ohms",
	ch->vdiv, ARRAY_SIZE(ch->vdiv));
	ch++;
	}

	return pdata;
	}

	static int gsc_hwmon_probe(struct platform_device *pdev)
	{
	struct gsc_dev *gsc = dev_get_drvdata(pdev->dev.parent);
	struct device *dev = &pdev->dev;
	struct device *hwmon_dev;
	struct gsc_hwmon_platform_data *pdata = dev_get_platdata(dev);
	struct gsc_hwmon_data *hwmon;
	const struct attribute_group **groups;
	int i, i_in, i_temp;

	if (!pdata) {
	pdata = gsc_hwmon_get_devtree_pdata(dev);
	if (IS_ERR(pdata))
	return PTR_ERR(pdata);
	}

	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
	if (!hwmon)
	return -ENOMEM;
	hwmon->gsc = gsc;
	hwmon->pdata = pdata;

	hwmon->regmap = devm_regmap_init(dev, &gsc_hwmon_regmap_bus,
	gsc->i2c_hwmon,
	&gsc_hwmon_regmap_config);
	if (IS_ERR(hwmon->regmap))
	return PTR_ERR(hwmon->regmap);

	for (i = 0, i_in = 0, i_temp = 0; i < hwmon->pdata->nchannels; i++) {
	const struct gsc_hwmon_channel *ch = &pdata->channels[i];

	switch (ch->mode) {
	case mode_temperature:
	if (i_temp == GSC_HWMON_MAX_TEMP_CH) {
	dev_err(gsc->dev, "too many temp channels\n");
	return -EINVAL;
	}
	hwmon->temp_ch[i_temp] = ch;
	hwmon->temp_config[i_temp] = HWMON_T_INPUT \|
	HWMON_T_LABEL;
	i_temp++;
	break;
	case mode_voltage_24bit:
	case mode_voltage_16bit:
	case mode_voltage_raw:
	if (i_in == GSC_HWMON_MAX_IN_CH) {
	dev_err(gsc->dev, "too many input channels\n");
	return -EINVAL;
	}
	hwmon->in_ch[i_in] = ch;
	hwmon->in_config[i_in] =
	HWMON_I_INPUT \| HWMON_I_LABEL;
	i_in++;
	break;
	default:
	dev_err(gsc->dev, "invalid mode: %d\n", ch->mode);
	return -EINVAL;
	}
	}

	/* setup config structures */
	hwmon->chip.ops = &gsc_hwmon_ops;
	hwmon->chip.info = hwmon->info;
	hwmon->info[0] = &hwmon->temp_info;
	hwmon->info[1] = &hwmon->in_info;
	hwmon->temp_info.type = hwmon_temp;
	hwmon->temp_info.config = hwmon->temp_config;
	hwmon->in_info.type = hwmon_in;
	hwmon->in_info.config = hwmon->in_config;

	groups = pdata->fan_base ? gsc_hwmon_groups : NULL;
	hwmon_dev = devm_hwmon_device_register_with_info(dev,
	KBUILD_MODNAME, hwmon,
	&hwmon->chip, groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct of_device_id gsc_hwmon_of_match[] = {
	{ .compatible = "gw,gsc-adc", },
	{}
	};

	static struct platform_driver gsc_hwmon_driver = {
	.driver = {
	.name = "gsc-hwmon",
	.of_match_table = gsc_hwmon_of_match,
	},
	.probe = gsc_hwmon_probe,
	};

	module_platform_driver(gsc_hwmon_driver);

	MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
	MODULE_DESCRIPTION("GSC hardware monitor driver");
	MODULE_LICENSE("GPL v2");