[PATCH v3 3/4] hwmon: add Gateworks System Controller support

[Tim Harvey <tharvey@gateworks.com>]

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.

Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
v3:
- add voltage_raw input type and supporting fields
- add channel validation to is_visible function
- remove unnecessary channel validation from read/write functions

v2:
- change license comment style
- remove DEBUG
- simplify regmap_bulk_read err check
- remove break after returns in switch statement
- fix fan setpoint buffer address
- remove unnecessary parens
- consistently use struct device *dev pointer
- change license/comment block
- add validation for hwmon child node props
- move parsing of of to own function
- use strlcpy to ensure null termination
- fix static array sizes and removed unnecessary initializers
- dynamically allocate channels
- fix fan input label
- support platform data
- fixed whitespace issues

 drivers/hwmon/Kconfig                   |   9 +
 drivers/hwmon/Makefile                  |   1 +
 drivers/hwmon/gsc-hwmon.c               | 368 ++++++++++++++++++++++++++++++++
 include/linux/platform_data/gsc_hwmon.h |  43 ++++
 4 files changed, 421 insertions(+)
 create mode 100644 drivers/hwmon/gsc-hwmon.c
 create mode 100644 include/linux/platform_data/gsc_hwmon.h

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 7ad0176..85d9aa3 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -475,6 +475,15 @@ 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
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 0fe489f..835a536 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -69,6 +69,7 @@ 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
diff --git a/drivers/hwmon/gsc-hwmon.c b/drivers/hwmon/gsc-hwmon.c
new file mode 100644
index 0000000..10da46f
--- /dev/null
+++ b/drivers/hwmon/gsc-hwmon.c
@@ -0,0 +1,368 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Gateworks Corporation
+ *
+ * This driver registers Linux HWMON attributes for GSC ADC's
+ */
+#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_MAX_FAN_CH	6
+
+struct gsc_hwmon_data {
+	struct gsc_dev *gsc;
+	struct device *dev;
+	struct gsc_hwmon_platform_data *pdata;
+	const struct gsc_hwmon_channel *temp_ch[GSC_HWMON_MAX_TEMP_CH];
+	const struct gsc_hwmon_channel *in_ch[GSC_HWMON_MAX_IN_CH];
+	const struct gsc_hwmon_channel *fan_ch[GSC_HWMON_MAX_FAN_CH];
+	u32 temp_config[GSC_HWMON_MAX_TEMP_CH + 1];
+	u32 in_config[GSC_HWMON_MAX_IN_CH + 1];
+	u32 fan_config[GSC_HWMON_MAX_FAN_CH + 1];
+	struct hwmon_channel_info temp_info;
+	struct hwmon_channel_info in_info;
+	struct hwmon_channel_info fan_info;
+	const struct hwmon_channel_info *info[4];
+	struct hwmon_chip_info chip;
+	int vreference;
+	int resolution;
+};
+
+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);
+	struct gsc_hwmon_platform_data *pdata = hwmon->pdata;
+	const struct gsc_hwmon_channel *ch;
+	int sz, ret;
+	u8 buf[3];
+
+	dev_dbg(dev, "%s type=%d attr=%d channel=%d\n", __func__, type, attr,
+		channel);
+	switch (type) {
+	case hwmon_in:
+		ch = hwmon->in_ch[channel];
+		break;
+	case hwmon_temp:
+		ch = hwmon->temp_ch[channel];
+		break;
+	case hwmon_fan:
+		ch = hwmon->fan_ch[channel];
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	sz = (ch->type == type_voltage) ? 3 : 2;
+	ret = regmap_bulk_read(hwmon->gsc->regmap_hwmon, ch->reg, buf, sz);
+	if (ret)
+		return ret;
+
+	*val = 0;
+	while (sz-- > 0)
+		*val |= (buf[sz] << (8*sz));
+
+	switch (ch->type) {
+	case type_temperature:
+		if ((type == hwmon_temp) && *val > 0x8000)
+			*val -= 0xffff;
+		break;
+	case type_voltage_raw:
+		/* scale based on ref voltage and resolution */
+		if (pdata->vreference && pdata->resolution) {
+			*val *= pdata->vreference;
+			*val /= pdata->resolution;
+		}
+		/* scale based on optional voltage divider */
+		if (ch->vdiv[0] && ch->vdiv[1]) {
+			*val *= (ch->vdiv[0] + ch->vdiv[1]);
+			*val /= ch->vdiv[1];
+		}
+		/* adjust by offset */
+		*val += ch->voffset;
+		break;
+	}
+
+	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);
+
+	dev_dbg(dev, "%s type=%d attr=%d channel=%d\n", __func__, type, attr,
+		channel);
+	switch (type) {
+	case hwmon_in:
+		*buf = hwmon->in_ch[channel]->name;
+		break;
+	case hwmon_temp:
+		*buf = hwmon->temp_ch[channel]->name;
+		break;
+	case hwmon_fan:
+		*buf = hwmon->fan_ch[channel]->name;
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	return 0;
+}
+
+static int
+gsc_hwmon_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+		int channel, long val)
+{
+	struct gsc_hwmon_data *hwmon = dev_get_drvdata(dev);
+	u8 buf[2];
+
+	dev_dbg(dev, "%s type=%d attr=%d channel=%d\n", __func__, type, attr,
+		channel);
+	switch (type) {
+	case hwmon_fan:
+		buf[0] = val & 0xff;
+		buf[1] = (val >> 8) & 0xff;
+		return regmap_bulk_write(hwmon->gsc->regmap_hwmon,
+					 hwmon->fan_ch[channel]->reg, buf, 2);
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static umode_t
+gsc_hwmon_is_visible(const void *_data, enum hwmon_sensor_types type, u32 attr,
+		     int ch)
+{
+	const struct gsc_hwmon_data *hwmon = _data;
+	struct device *dev = hwmon->gsc->dev;
+	umode_t mode = 0;
+
+	switch (type) {
+	case hwmon_fan:
+		if (ch >= GSC_HWMON_MAX_FAN_CH)
+			return -EOPNOTSUPP;
+		mode = S_IRUGO;
+		if (attr == hwmon_fan_input)
+			mode |= S_IWUSR;
+		break;
+	case hwmon_temp:
+		if (ch >= GSC_HWMON_MAX_TEMP_CH)
+			return -EOPNOTSUPP;
+		mode = S_IRUGO;
+		break;
+	case hwmon_in:
+		if (ch >= GSC_HWMON_MAX_IN_CH)
+			return -EOPNOTSUPP;
+		mode = S_IRUGO;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	dev_dbg(dev, "%s type=%d attr=%d ch=%d mode=0x%x\n", __func__, type,
+		attr, ch, mode);
+
+	return mode;
+}
+
+static const struct hwmon_ops gsc_hwmon_ops = {
+	.is_visible = gsc_hwmon_is_visible,
+	.read = gsc_hwmon_read,
+	.read_string = gsc_hwmon_read_string,
+	.write = gsc_hwmon_write,
+};
+
+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;
+	const char *type;
+	int nchannels;
+
+	nchannels = device_get_child_node_count(dev);
+	dev_dbg(dev, "channels=%d\n", nchannels);
+	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;
+
+	device_property_read_u32(dev, "gw,reference-voltage",
+				 &pdata->vreference);
+	device_property_read_u32(dev, "gw,resolution", &pdata->resolution);
+
+	/* 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_string(child, "type", &type)) {
+			dev_err(dev, "channel without type\n");
+			fwnode_handle_put(child);
+			return ERR_PTR(-EINVAL);
+		}
+		if (!strcasecmp(type, "gw,hwmon-temperature"))
+			ch->type = type_temperature;
+		else if (!strcasecmp(type, "gw,hwmon-voltage"))
+			ch->type = type_voltage;
+		else if (!strcasecmp(type, "gw,hwmon-voltage-raw"))
+			ch->type = type_voltage_raw;
+		else if (!strcasecmp(type, "gw,hwmon-fan"))
+			ch->type = type_fan;
+		else {
+			dev_err(dev, "channel without type\n");
+			fwnode_handle_put(child);
+			return ERR_PTR(-EINVAL);
+		}
+
+		fwnode_property_read_u32(child, "gw,voltage-offset",
+			&ch->voffset);
+		fwnode_property_read_u32_array(child, "gw,voltage-divider",
+			ch->vdiv, ARRAY_SIZE(ch->vdiv));
+		dev_dbg(dev, "of: reg=0x%02x type=%d %s\n", ch->reg, ch->type,
+			ch->name);
+		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 gsc_hwmon_platform_data *pdata = dev_get_platdata(dev);
+	struct gsc_hwmon_data *hwmon;
+	int i, i_in, i_temp, i_fan;
+
+	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;
+
+	for (i = 0, i_in = 0, i_temp = 0, i_fan = 0;
+	     i < hwmon->pdata->nchannels; i++) {
+		const struct gsc_hwmon_channel *ch = &pdata->channels[i];
+
+		if (ch->reg > GSC_HWMON_MAX_REG) {
+			dev_err(dev, "invalid reg: 0x%02x\n", ch->reg);
+			return -EINVAL;
+		}
+		switch (ch->type) {
+		case type_temperature:
+			if (i_temp == GSC_HWMON_MAX_TEMP_CH) {
+				dev_err(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 type_voltage:
+		case type_voltage_raw:
+			if (i_in == GSC_HWMON_MAX_IN_CH) {
+				dev_err(dev, "too many voltage channels\n");
+				return -EINVAL;
+			}
+			hwmon->in_ch[i_in] = ch;
+			hwmon->in_config[i_in] =
+				HWMON_I_INPUT | HWMON_I_LABEL;
+			i_in++;
+			break;
+		case type_fan:
+			if (i_fan == GSC_HWMON_MAX_FAN_CH) {
+				dev_err(dev, "too many voltage channels\n");
+				return -EINVAL;
+			}
+			hwmon->fan_ch[i_fan] = ch;
+			hwmon->fan_config[i_fan] =
+				HWMON_F_INPUT | HWMON_F_LABEL;
+			i_fan++;
+			break;
+		default:
+			dev_err(dev, "invalid type: %d\n", ch->type);
+			return -EINVAL;
+		}
+		dev_dbg(dev, "pdata: reg=0x%02x type=%d %s\n", ch->reg,
+			ch->type, ch->name);
+	}
+
+	/* terminate channel config lists */
+	hwmon->temp_config[i_temp] = 0;
+	hwmon->in_config[i_in] = 0;
+	hwmon->fan_config[i_fan] = 0;
+
+	/* 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->info[2] = &hwmon->fan_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;
+	hwmon->fan_info.type = hwmon_fan;
+	hwmon->fan_info.config = hwmon->fan_config;
+
+	hwmon->dev = devm_hwmon_device_register_with_info(dev,
+							  KBUILD_MODNAME, hwmon,
+							  &hwmon->chip, NULL);
+	return PTR_ERR_OR_ZERO(hwmon->dev);
+}
+
+static const struct of_device_id gsc_hwmon_of_match[] = {
+	{ .compatible = "gw,gsc-hwmon", },
+	{}
+};
+
+static struct platform_driver gsc_hwmon_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.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");
diff --git a/include/linux/platform_data/gsc_hwmon.h b/include/linux/platform_data/gsc_hwmon.h
new file mode 100644
index 0000000..5e59846
--- /dev/null
+++ b/include/linux/platform_data/gsc_hwmon.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _GSC_HWMON_H
+#define _GSC_HWMON_H
+
+enum gsc_hwmon_type {
+	type_temperature,
+	type_voltage,
+	type_voltage_raw,
+	type_fan,
+};
+
+/**
+ * struct gsc_hwmon_channel - configuration parameters
+ * @reg:  I2C register offset
+ * @type: channel type
+ * @name: channel name
+ * @voffset: voltage offset (mV)
+ * @vdiv: voltage divider array (2 resistor values in ohms)
+ */
+struct gsc_hwmon_channel {
+	unsigned int reg;
+	unsigned int type;
+	const char *name;
+	unsigned int voffset;
+	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 resolution
+ */
+struct gsc_hwmon_platform_data {
+	const struct gsc_hwmon_channel *channels;
+	int nchannels;
+	unsigned int resolution;
+	unsigned int vreference;
+};
+
+#endif
-- 
2.7.4