hwmon: add POWER-Z driver

POWER-Z is a series of devices to monitor power characteristics of
USB-C connections and display those on a on-device display.
Some of the devices, notably KM002C and KM003C, contain an additional
port which exposes the measurements via USB.

This is a driver for this monitor port.

It was developed and tested with the KM003C.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230902-powerz-v4-1-7ec2c1440687@weissschuh.net
[groeck:
 Release urb after hwmon registration error;
 Move priv->status initialization to correct place before reinit_completion
 ]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -178,6 +178,7 @@ Hardware Monitoring Kernel Drivers
    peci-cputemp
    peci-dimmtemp
    pmbus
+   powerz
    powr1220
    pxe1610
    pwm-fan

Documentation/hwmon/powerz.rst

+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver POWERZ
+====================
+
+Supported chips:
+
+  * ChargerLAB POWER-Z KM003C
+
+    Prefix: 'powerz'
+
+    Addresses scanned: -
+
+Author:
+
+  - Thomas Weißschuh <linux@weissschuh.net>
+
+Description
+-----------
+
+This driver implements support for the ChargerLAB POWER-Z USB-C power testing
+family.
+
+The device communicates with the custom protocol over USB.
+
+The channel labels exposed via hwmon match the labels used by the on-device
+display and the official POWER-Z PC software.
+
+As current can flow in both directions through the tester the sign of the
+channel "curr1_input" (label "IBUS") indicates the direction.

MAINTAINERS

@@ -4794,6 +4794,13 @@ X:	drivers/char/ipmi/
 X:	drivers/char/random.c
 X:	drivers/char/tpm/
 
+CHARGERLAB POWER-Z HARDWARE MONITOR DRIVER
+M:	Thomas Weißschuh <linux@weissschuh.net>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/powerz.rst
+F:	drivers/hwmon/powerz.c
+
 CHECKPATCH
 M:	Andy Whitcroft <apw@canonical.com>
 M:	Joe Perches <joe@perches.com>

drivers/hwmon/Kconfig

@@ -839,6 +839,16 @@ config SENSORS_JC42
 	  This driver can also be built as a module. If so, the module
 	  will be called jc42.
 
+config SENSORS_POWERZ
+	tristate "ChargerLAB POWER-Z USB-C tester"
+	depends on USB
+	help
+	  If you say yes here you get support for ChargerLAB POWER-Z series of
+	  USB-C charging testers.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called powerz.
+
 config SENSORS_POWR1220
 	tristate "Lattice POWR1220 Power Monitoring"
 	depends on I2C

drivers/hwmon/Makefile

@@ -176,6 +176,7 @@ obj-$(CONFIG_SENSORS_OXP) += oxp-sensors.o
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
 obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
+obj-$(CONFIG_SENSORS_POWERZ)	+= powerz.o
 obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o

drivers/hwmon/powerz.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+
+#define DRIVER_NAME	"powerz"
+#define POWERZ_EP_CMD_OUT	0x01
+#define POWERZ_EP_DATA_IN	0x81
+
+struct powerz_sensor_data {
+	u8 _unknown_1[8];
+	__le32 V_bus;
+	__le32 I_bus;
+	__le32 V_bus_avg;
+	__le32 I_bus_avg;
+	u8 _unknown_2[8];
+	u8 temp[2];
+	__le16 V_cc1;
+	__le16 V_cc2;
+	__le16 V_dp;
+	__le16 V_dm;
+	__le16 V_dd;
+	u8 _unknown_3[4];
+} __packed;
+
+struct powerz_priv {
+	char transfer_buffer[64];	/* first member to satisfy DMA alignment */
+	struct mutex mutex;
+	struct completion completion;
+	struct urb *urb;
+	int status;
+};
+
+static const struct hwmon_channel_info *const powerz_info[] = {
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_AVERAGE,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_LABEL | HWMON_C_AVERAGE),
+	    HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static umode_t powerz_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	return 0444;
+}
+
+static int powerz_read_string(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, const char **str)
+{
+	if (type == hwmon_curr && attr == hwmon_curr_label) {
+		*str = "IBUS";
+	} else if (type == hwmon_in && attr == hwmon_in_label) {
+		if (channel == 0)
+			*str = "VBUS";
+		else if (channel == 1)
+			*str = "VCC1";
+		else if (channel == 2)
+			*str = "VCC2";
+		else if (channel == 3)
+			*str = "VDP";
+		else if (channel == 4)
+			*str = "VDM";
+		else if (channel == 5)
+			*str = "VDD";
+		else
+			return -EOPNOTSUPP;
+	} else if (type == hwmon_temp && attr == hwmon_temp_label) {
+		*str = "TEMP";
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static void powerz_usb_data_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	complete(&priv->completion);
+}
+
+static void powerz_usb_cmd_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	usb_fill_bulk_urb(urb, urb->dev,
+			  usb_rcvbulkpipe(urb->dev, POWERZ_EP_DATA_IN),
+			  priv->transfer_buffer, sizeof(priv->transfer_buffer),
+			  powerz_usb_data_complete, priv);
+
+	priv->status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (priv->status)
+		complete(&priv->completion);
+}
+
+static int powerz_read_data(struct usb_device *udev, struct powerz_priv *priv)
+{
+	int ret;
+
+	priv->status = -ETIMEDOUT;
+	reinit_completion(&priv->completion);
+
+	priv->transfer_buffer[0] = 0x0c;
+	priv->transfer_buffer[1] = 0x00;
+	priv->transfer_buffer[2] = 0x02;
+	priv->transfer_buffer[3] = 0x00;
+
+	usb_fill_bulk_urb(priv->urb, udev,
+			  usb_sndbulkpipe(udev, POWERZ_EP_CMD_OUT),
+			  priv->transfer_buffer, 4, powerz_usb_cmd_complete,
+			  priv);
+	ret = usb_submit_urb(priv->urb, GFP_KERNEL);
+	if (ret)
+		return ret;
+
+	if (!wait_for_completion_interruptible_timeout
+	    (&priv->completion, msecs_to_jiffies(5))) {
+		usb_kill_urb(priv->urb);
+		return -EIO;
+	}
+
+	if (priv->urb->actual_length < sizeof(struct powerz_sensor_data))
+		return -EIO;
+
+	return priv->status;
+}
+
+static int powerz_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct usb_interface *intf = to_usb_interface(dev->parent);
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+	struct powerz_sensor_data *data;
+	int ret;
+
+	if (!priv)
+		return -EIO;	/* disconnected */
+
+	mutex_lock(&priv->mutex);
+	ret = powerz_read_data(udev, priv);
+	if (ret)
+		goto out;
+
+	data = (struct powerz_sensor_data *)priv->transfer_buffer;
+
+	if (type == hwmon_curr) {
+		if (attr == hwmon_curr_input)
+			*val = ((s32)le32_to_cpu(data->I_bus)) / 1000;
+		else if (attr == hwmon_curr_average)
+			*val = ((s32)le32_to_cpu(data->I_bus_avg)) / 1000;
+		else
+			ret = -EOPNOTSUPP;
+	} else if (type == hwmon_in) {
+		if (attr == hwmon_in_input) {
+			if (channel == 0)
+				*val = le32_to_cpu(data->V_bus) / 1000;
+			else if (channel == 1)
+				*val = le16_to_cpu(data->V_cc1) / 10;
+			else if (channel == 2)
+				*val = le16_to_cpu(data->V_cc2) / 10;
+			else if (channel == 3)
+				*val = le16_to_cpu(data->V_dp) / 10;
+			else if (channel == 4)
+				*val = le16_to_cpu(data->V_dm) / 10;
+			else if (channel == 5)
+				*val = le16_to_cpu(data->V_dd) / 10;
+			else
+				ret = -EOPNOTSUPP;
+		} else if (attr == hwmon_in_average && channel == 0) {
+			*val = le32_to_cpu(data->V_bus_avg) / 1000;
+		} else {
+			ret = -EOPNOTSUPP;
+		}
+	} else if (type == hwmon_temp && attr == hwmon_temp_input) {
+		*val = data->temp[1] * 2000 + data->temp[0] * 1000 / 128;
+	} else {
+		ret = -EOPNOTSUPP;
+	}
+
+out:
+	mutex_unlock(&priv->mutex);
+	return ret;
+}
+
+static const struct hwmon_ops powerz_hwmon_ops = {
+	.is_visible = powerz_is_visible,
+	.read = powerz_read,
+	.read_string = powerz_read_string,
+};
+
+static const struct hwmon_chip_info powerz_chip_info = {
+	.ops = &powerz_hwmon_ops,
+	.info = powerz_info,
+};
+
+static int powerz_probe(struct usb_interface *intf,
+			const struct usb_device_id *id)
+{
+	struct powerz_priv *priv;
+	struct device *hwmon_dev;
+	struct device *parent;
+
+	parent = &intf->dev;
+
+	priv = devm_kzalloc(parent, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!priv->urb)
+		return -ENOMEM;
+	mutex_init(&priv->mutex);
+	init_completion(&priv->completion);
+
+	hwmon_dev =
+	    devm_hwmon_device_register_with_info(parent, DRIVER_NAME, priv,
+						 &powerz_chip_info, NULL);
+	if (IS_ERR(hwmon_dev)) {
+		usb_free_urb(priv->urb);
+		return PTR_ERR(hwmon_dev);
+	}
+
+	usb_set_intfdata(intf, priv);
+
+	return 0;
+}
+
+static void powerz_disconnect(struct usb_interface *intf)
+{
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+
+	mutex_lock(&priv->mutex);
+	usb_kill_urb(priv->urb);
+	usb_free_urb(priv->urb);
+	mutex_unlock(&priv->mutex);
+}
+
+static const struct usb_device_id powerz_id_table[] = {
+	{ USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0063, 0x00) },	/* ChargerLAB POWER-Z KM003C */
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, powerz_id_table);
+
+static struct usb_driver powerz_driver = {
+	.name = DRIVER_NAME,
+	.id_table = powerz_id_table,
+	.probe = powerz_probe,
+	.disconnect = powerz_disconnect,
+};
+
+module_usb_driver(powerz_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
+MODULE_DESCRIPTION("ChargerLAB POWER-Z USB-C tester");