hwmon: Add Gateworks System Controller support

The Gateworks System Controller has a hwmon sub-component that exposes
up to 16 ADC's, some of which are temperature sensors, others which are
voltage inputs. The ADC configuration (register mapping and name) is
configured via device-tree and varies board to board.
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/hwmon/gsc-hwmon.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver gsc-hwmon
+=======================
+
+Supported chips: Gateworks GSC
+Datasheet: http://trac.gateworks.com/wiki/gsc
+Author: Tim Harvey <tharvey@gateworks.com>
+
+Description:
+------------
+
+This driver supports hardware monitoring for the temperature sensor,
+various ADC's connected to the GSC, and optional FAN controller available
+on some boards.
+
+
+Voltage Monitoring
+------------------
+
+The voltage inputs are scaled either internally or by the driver depending
+on the GSC version and firmware. The values returned by the driver do not need
+further scaling. The voltage input labels provide the voltage rail name:
+
+inX_input                  Measured voltage (mV).
+inX_label                  Name of voltage rail.
+
+
+Temperature Monitoring
+----------------------
+
+Temperatures are measured with 12-bit or 10-bit resolution and are scaled
+either internally or by the driver depending on the GSC version and firmware.
+The values returned by the driver reflect millidegree Celcius:
+
+tempX_input                Measured temperature.
+tempX_label                Name of temperature input.
+
+
+PWM Output Control
+------------------
+
+The GSC features 1 PWM output that operates in automatic mode where the
+PWM value will be scalled depending on 6 temperature boundaries.
+The tempeature boundaries are read-write and in millidegree Celcius and the
+read-only PWM values range from 0 (off) to 255 (full speed).
+Fan speed will be set to minimum (off) when the temperature sensor reads
+less than pwm1_auto_point1_temp and maximum when the temperature sensor
+equals or exceeds pwm1_auto_point6_temp.
+
+pwm1_auto_point[1-6]_pwm       PWM value.
+pwm1_auto_point[1-6]_temp      Temperature boundary.
+

Documentation/hwmon/index.rst

@@ -60,6 +60,7 @@ Hardware Monitoring Kernel Drivers
    ftsteutates
    g760a
    g762
+   gsc-hwmon
    gl518sm
    hih6130
    ibmaem

MAINTAINERS

@@ -7035,6 +7035,9 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
 F:	drivers/mfd/gateworks-gsc.c
 F:	include/linux/mfd/gsc.h
+F:	Documentation/hwmon/gsc-hwmon.rst
+F:	drivers/hwmon/gsc-hwmon.c
+F:	include/linux/platform_data/gsc_hwmon.h
 
 GASKET DRIVER FRAMEWORK
 M:	Rob Springer <rspringer@google.com>

drivers/hwmon/Kconfig

@@ -523,6 +523,15 @@ config SENSORS_F75375S
 	  This driver can also be built as a module. If so, the module
 	  will be called f75375s.
 
+config SENSORS_GSC
+	tristate "Gateworks System Controller ADC"
+	depends on MFD_GATEWORKS_GSC
+	help
+	  Support for the Gateworks System Controller A/D converters.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called gsc-hwmon.
+
 config SENSORS_MC13783_ADC
         tristate "Freescale MC13783/MC13892 ADC"
         depends on MFD_MC13XXX

drivers/hwmon/Makefile

@@ -74,6 +74,7 @@ obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
 obj-$(CONFIG_SENSORS_G762)	+= g762.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
+obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o

drivers/hwmon/gsc-hwmon.c

+// 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) ? 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;
+		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:
+		/* 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:
+		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");

include/linux/platform_data/gsc_hwmon.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _GSC_HWMON_H
+#define _GSC_HWMON_H
+
+enum gsc_hwmon_mode {
+	mode_temperature,
+	mode_voltage,
+	mode_voltage_raw,
+	mode_max,
+};
+
+/**
+ * struct gsc_hwmon_channel - configuration parameters
+ * @reg:  I2C register offset
+ * @mode: channel mode
+ * @name: channel name
+ * @mvoffset: voltage offset
+ * @vdiv: voltage divider array (2 resistor values in milli-ohms)
+ */
+struct gsc_hwmon_channel {
+	unsigned int reg;
+	unsigned int mode;
+	const char *name;
+	unsigned int mvoffset;
+	unsigned int vdiv[2];
+};
+
+/**
+ * struct gsc_hwmon_platform_data - platform data for gsc_hwmon driver
+ * @channels:	pointer to array of gsc_hwmon_channel structures
+ *		describing channels
+ * @nchannels:	number of elements in @channels array
+ * @vreference: voltage reference (mV)
+ * @resolution: ADC bit resolution
+ * @fan_base: register base for FAN controller
+ */
+struct gsc_hwmon_platform_data {
+	const struct gsc_hwmon_channel *channels;
+	int nchannels;
+	unsigned int resolution;
+	unsigned int vreference;
+	unsigned int fan_base;
+};
+#endif