Initial driver for the MAX31785 intelligent fan controller

PATCH Guenter Roeck 2 participants 14 messages Sep 19, 2016 – Oct 11, 2016 Hardware monitoring

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Guenter Roeck

author maintainer

2016-09-19 01:41 UTC #0 lore raw

Quoted 7 lines · Timothy Pearson

Add a basic driver for the MAX31785, focusing on the fan control features but ignoring the temperature and voltage monitoring features of the device.
This driver supports all fan control modes and tachometer / PWM readback where applicable.

Could you try using hwmon_device_register_with_info() as available in linux-next ? Hopefully that should reduce driver size (and give the new API some test coverage).

Please run the patch through checkpatch --strict. I don't expect you to fix all the problems is reports, but the following should be addressed.

CHECK: Prefer kernel type 'u8' over 'uint8_t'
CHECK: Prefer kernel type 'u16' over 'uint16_t'
CHECK: Alignment should match open parenthesis
CHECK: Logical continuations should be on the previous line
WARNING: quoted string split across lines

Additional comments inline.

Quoted 40 lines

Signed-off-by Timothy Pearson <[email protected]>

---
 Documentation/hwmon/max31785 |   36 +++
 drivers/hwmon/Kconfig        |   10 +
 drivers/hwmon/Makefile       |    1 +
 drivers/hwmon/max31785.c     |  713 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 760 insertions(+)
 create mode 100644 Documentation/hwmon/max31785
 create mode 100644 drivers/hwmon/max31785.c

Documentation/hwmon/max31785 new file +24 -0

new file mode 100644
index 0000000..34dca74
@@ -0,0 +1,36 @@
+Kernel driver max31785
+======================
+
+Supported chips:
+  * Maxim MAX31785
+    Prefix: 'max31785'
+    Addresses scanned: 0x52 0x53 0x54 0x55
+    Datasheet: http://pdfserv.maximintegrated.com/en/ds/MAX31785.pdf
+
+Author: Timothy Pearson <[email protected]>
+
+
+Description
+-----------
+
+This driver implements support for the Maxim MAX31785 chip.
+
+The MAX31785 controls the speeds of up to six fans using six independent
+PWM outputs. The desired fan speeds (or PWM duty cycles) are written
+through the I2C interface. The outputs drive "4-wire" fans directly,
+or can be used to modulate the fan's power terminals using an external
+pass transistor.
+
+Tachometer inputs monitor fan tachometer logic outputs for precise (+/-1%)

Documentation/hwmon/max31785 line 34

Quoted 10 lines

Documentation/hwmon/max31785 new file +10 -0

+monitoring and control of fan RPM as well as detection of fan failure.
+
+
+Sysfs entries
+-------------
+
+fan[1-6]_input           RO  fan tachometer speed in RPM
+fan[1-6]_fault           RO  fan experienced fault
+fan[1-6]_target          RW  desired fan speed in RPM
+fan[1-6]_control_mode    RW  desired control mode: rpm, pwm, or auto

Please use pwm[]_enable (see API)

Documentation/hwmon/max31785 line 35

Quoted 1 line

Documentation/hwmon/max31785 new file +1 -0
+pwm[1-6]_enable          RW  output enabled, 0=disabled, 1=enabled

Per API: 0 = no fan speed control (full speed), 1 = manual fan speed control enabled (using pwm[1-*]), 2+: automatic fan speed control

Quoted 147 lines

Documentation/hwmon/max31785 new file +1 -0

+pwm[1-6]                 RW  fan target duty cycle (0-255)

drivers/hwmon/Kconfig +10 -0

index eaf2f91..a202fd5 100644
@@ -886,6 +886,16 @@ config SENSORS_MAX6697
 	  This driver can also be built as a module.  If so, the module
 	  will be called max6697.
 
+config SENSORS_MAX31785
+	tristate "Maxim MAX31785 sensor chip"
+	depends on I2C
+	help
+	  If you say yes here you get support for 6-Channel PWM-Output
+	  Fan RPM Controller.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called max31785.
+
 config SENSORS_MAX31790
 	tristate "Maxim MAX31790 sensor chip"
 	depends on I2C

drivers/hwmon/Makefile +1 -0

index fe87d28..44c0c02 100644
@@ -119,6 +119,7 @@ obj-$(CONFIG_SENSORS_MAX6639)	+= max6639.o
 obj-$(CONFIG_SENSORS_MAX6642)	+= max6642.o
 obj-$(CONFIG_SENSORS_MAX6650)	+= max6650.o
 obj-$(CONFIG_SENSORS_MAX6697)	+= max6697.o
+obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX31790)	+= max31790.o
 obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
 obj-$(CONFIG_SENSORS_MCP3021)	+= mcp3021.o

drivers/hwmon/max31785.c new file +107 -0

new file mode 100644
index 0000000..9a23edd
@@ -0,0 +1,713 @@
+/*
+ * max31785.c - Part of lm_sensors, Linux kernel modules for hardware
+ *             monitoring.
+ *
+ * (C) 2016 Raptor Engineering, LLC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/* MAX31785 registers */
+#define MAX31785_REG_PAGE			0x00
+#define MAX31785_PAGE_FAN_CONFIG(ch)		(0x00 + (ch))
+#define MAX31785_REG_FAN_CONFIG_1_2		0x3a
+#define MAX31785_REG_FAN_COMMAND_1		0x3b
+#define MAX31785_REG_STATUS_FANS_1_2		0x81
+#define MAX31785_REG_FAN_SPEED_1		0x90
+#define MAX31785_REG_MFR_ID			0x99
+#define MAX31785_REG_MFR_MODEL			0x9a
+#define MAX31785_REG_MFR_FAN_CONFIG		0xf1
+#define MAX31785_REG_READ_FAN_PWM		0xf3
+
+/* Fan Config register bits */
+#define MAX31785_FAN_CFG_PWM_ENABLE		0x80
+#define MAX31785_FAN_CFG_CONTROL_MODE_RPM	0x40
+
+/* Fan Status register bits */
+#define MAX31785_FAN_STATUS_FAULT_MASK		0x80
+
+#define NR_CHANNEL				6
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x52, 0x53, 0x54, 0x55,
+							I2C_CLIENT_END };
+
+/*
+ * Client data (each client gets its own)
+ */
+struct max31785_data {
+	struct i2c_client *client;
+	struct mutex device_lock;
+	bool valid; /* zero until following fields are valid */
+	unsigned long last_updated; /* in jiffies */
+
+	/* register values */
+	uint8_t fan_config[NR_CHANNEL];
+	uint16_t fan_command[NR_CHANNEL];
+	uint8_t mfr_fan_config[NR_CHANNEL];
+	uint8_t fault_status[NR_CHANNEL];
+	uint16_t tach_rpm[NR_CHANNEL];
+	uint16_t pwm[NR_CHANNEL];
+};
+
+static int max31785_set_page(struct i2c_client *client,
+				uint8_t page)
+{
+	return i2c_smbus_write_byte_data(client,
+			MAX31785_REG_PAGE,
+			page);
+}
+
+static int max31785_read_fan_data(struct i2c_client *client,
+				uint8_t fan, uint8_t reg, uint8_t byte_mode)
+{
+	int rv;
+
+	rv = max31785_set_page(client, MAX31785_PAGE_FAN_CONFIG(fan));
+	if (rv < 0)
+		return rv;
+
+	if (byte_mode)
+		rv = i2c_smbus_read_byte_data(client, reg);
+	else
+		rv = i2c_smbus_read_word_data(client, reg);
+
+	return rv;
+}
+
+static int max31785_write_fan_data(struct i2c_client *client,
+				uint8_t fan, uint8_t reg, uint16_t data,
+				uint8_t byte_mode)
+{
+	int err;
+
+	err = max31785_set_page(client, MAX31785_PAGE_FAN_CONFIG(fan));
+	if (err < 0)
+		return err;
+
+	if (byte_mode)
+		err = i2c_smbus_write_byte_data(client, reg, data);
+	else

drivers/hwmon/max31785.c line 117

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+		err = i2c_smbus_write_word_data(client, reg, data);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static uint8_t is_automatic_control_mode(struct max31785_data *data,
+			int index)

Please use bool as return value

drivers/hwmon/max31785.c line 122

Quoted 5 lines

drivers/hwmon/max31785.c new file +5 -0

+{
+	if (data->fan_command[index] > 0x7fff)
+		return 1;
+	else
+		return 0;

	return data->fan_command[index] > 0x7fff;

Quoted 78 lines

drivers/hwmon/max31785.c new file +78 -0

+}
+
+static struct max31785_data *max31785_update_device(struct device *dev)
+{
+	struct max31785_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	struct max31785_data *ret = data;
+	int i;
+	int rv;
+
+	mutex_lock(&data->device_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+		for (i = 0; i < NR_CHANNEL; i++) {
+			rv = max31785_read_fan_data(client, i,
+					MAX31785_REG_STATUS_FANS_1_2, 1);
+			if (rv < 0)
+				goto abort;
+			data->fault_status[i] = rv;
+
+			rv = max31785_read_fan_data(client, i,
+					MAX31785_REG_FAN_SPEED_1, 0);
+			if (rv < 0)
+				goto abort;
+			data->tach_rpm[i] = rv;
+
+			if ((data->fan_config[i]
+				& MAX31785_FAN_CFG_CONTROL_MODE_RPM)
+				|| is_automatic_control_mode(data, i)) {
+				rv = max31785_read_fan_data(client, i,
+						MAX31785_REG_READ_FAN_PWM, 0);
+				if (rv < 0)
+					goto abort;
+				data->pwm[i] = rv;
+			}
+
+			if (!is_automatic_control_mode(data, i)) {
+				/* Poke watchdog for manual fan control */
+				rv = max31785_write_fan_data(client,
+					i, MAX31785_REG_FAN_COMMAND_1,
+					data->fan_command[i], 0);
+				if (rv < 0)
+					goto abort;
+			}
+		}
+
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+	goto done;
+
+abort:
+	data->valid = false;
+	ret = ERR_PTR(rv);
+
+done:
+	mutex_unlock(&data->device_lock);
+
+	return ret;
+}
+
+static ssize_t get_fan(struct device *dev,
+		       struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = max31785_update_device(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", data->tach_rpm[attr->index]);
+}
+
+static ssize_t get_fan_target(struct device *dev,
+			      struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = max31785_update_device(dev);

drivers/hwmon/max31785.c line 210

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+	int rpm;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	if (data->fan_config[attr->index]
+		& MAX31785_FAN_CFG_CONTROL_MODE_RPM)
+		rpm = data->fan_command[attr->index];
+	else
+		rpm = data->fan_command[attr->index] / 40;

Why / 40 ?

Quoted 18 lines

drivers/hwmon/max31785.c new file +18 -0

+
+	return sprintf(buf, "%d\n", rpm);
+}
+
+static ssize_t set_fan_target(struct device *dev,
+			      struct device_attribute *devattr,
+			      const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	unsigned long rpm;
+	int err;
+
+	err = kstrtoul(buf, 10, &rpm);
+	if (err)
+		return err;
+

drivers/hwmon/max31785.c line 238

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+	if (rpm > 0x7fff)
+		return -EINVAL;
+
+	mutex_lock(&data->device_lock);
+
+	/* Switch fan to RPM mode */
+	data->fan_config[attr->index] |= MAX31785_FAN_CFG_CONTROL_MODE_RPM;
+	err = max31785_write_fan_data(client, attr->index,
+				MAX31785_REG_FAN_CONFIG_1_2,
+				data->fan_config[attr->index], 1);

We don't usually make such implied changes. The user should be able to set the target speed and then request the mode change explicitly.

Quoted 26 lines

drivers/hwmon/max31785.c new file +26 -0

+
+	if (err < 0) {
+		mutex_unlock(&data->device_lock);
+		return err;
+	}
+
+	/* Write new RPM value */
+	data->fan_command[attr->index] = rpm;
+	err = max31785_write_fan_data(client, attr->index,
+				MAX31785_REG_FAN_COMMAND_1,
+				data->fan_command[attr->index], 0);
+
+	mutex_unlock(&data->device_lock);
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static ssize_t get_pwm(struct device *dev,
+		       struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = max31785_update_device(dev);
+	int pwm;

drivers/hwmon/max31785.c line 274

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	if ((data->fan_config[attr->index]
+		& MAX31785_FAN_CFG_CONTROL_MODE_RPM)
+		|| is_automatic_control_mode(data, attr->index))
+		pwm = data->pwm[attr->index] / 100;
+	else
+		pwm = data->fan_command[attr->index] / 40;

Why / 40 ?

Quoted 19 lines

drivers/hwmon/max31785.c new file +19 -0

+
+	return sprintf(buf, "%d\n", pwm);
+}
+
+static ssize_t set_pwm(struct device *dev,
+		       struct device_attribute *devattr,
+		       const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	unsigned long pwm;
+	int err;
+
+	err = kstrtoul(buf, 10, &pwm);
+	if (err)
+		return err;
+
+	if (pwm > 255)

drivers/hwmon/max31785.c line 303

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+		return -EINVAL;
+
+	mutex_lock(&data->device_lock);
+
+	/* Switch fan to PWM mode */
+	data->fan_config[attr->index] &= ~MAX31785_FAN_CFG_CONTROL_MODE_RPM;
+	err = max31785_write_fan_data(client, attr->index,
+				MAX31785_REG_FAN_CONFIG_1_2,
+				data->fan_config[attr->index], 1);
+

Another implied mode change ...

drivers/hwmon/max31785.c line 310

Quoted 7 lines

drivers/hwmon/max31785.c new file +7 -0

+	if (err < 0) {
+		mutex_unlock(&data->device_lock);
+		return err;
+	}
+
+	/* Write new PWM value */
+	data->fan_command[attr->index] = pwm * 40;

Where is the * 40 coming from ?

Quoted 16 lines

drivers/hwmon/max31785.c new file +16 -0

+	err = max31785_write_fan_data(client, attr->index,
+				MAX31785_REG_FAN_COMMAND_1,
+				data->fan_command[attr->index], 0);
+
+	mutex_unlock(&data->device_lock);
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static ssize_t get_pwm_enable(struct device *dev,
+			      struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

drivers/hwmon/max31785.c line 336

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+	struct max31785_data *data = max31785_update_device(dev);
+	int enabled;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	if (data->fan_config[attr->index] & MAX31785_FAN_CFG_PWM_ENABLE)
+		enabled = 1;
+	else
+		enabled = 0;

	enabled = !!(data->fan_config[attr->index] &
		     MAX31785_FAN_CFG_PWM_ENABLE);

Quoted 237 lines

drivers/hwmon/max31785.c new file +237 -0

+
+	return sprintf(buf, "%d\n", enabled);
+}
+
+static ssize_t set_pwm_enable(struct device *dev,
+			      struct device_attribute *devattr,
+			      const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	unsigned long enabled;
+	int err;
+
+	err = kstrtoul(buf, 10, &enabled);
+	if (err)
+		return err;
+
+	switch (enabled) {
+	case 0:
+		data->fan_config[attr->index] =
+			data->fan_config[attr->index]
+			& ~MAX31785_FAN_CFG_PWM_ENABLE;
+		break;
+	case 1:
+		data->fan_config[attr->index] =
+			data->fan_config[attr->index]
+			 | MAX31785_FAN_CFG_PWM_ENABLE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	mutex_lock(&data->device_lock);
+
+	err = max31785_write_fan_data(client, attr->index,
+				MAX31785_REG_FAN_CONFIG_1_2,
+				data->fan_config[attr->index], 1);
+
+	mutex_unlock(&data->device_lock);
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static ssize_t get_control_mode(struct device *dev,
+			      struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = max31785_update_device(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	if (is_automatic_control_mode(data, attr->index))
+		return sprintf(buf, "auto\n");
+	else if (data->fan_config[attr->index]
+				& MAX31785_FAN_CFG_CONTROL_MODE_RPM)
+		return sprintf(buf, "rpm\n");
+
+	return sprintf(buf, "pwm\n");
+}
+
+static ssize_t set_control_mode(struct device *dev,
+			      struct device_attribute *devattr,
+			      const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int err;
+
+	if (!strcmp(buf, "auto") || !strcmp(buf, "auto\n")) {
+		data->fan_command[attr->index] = 0xffff;
+	} else if (!strcmp(buf, "pwm") || !strcmp(buf, "pwm\n")) {
+		data->fan_config[attr->index] =
+			data->fan_config[attr->index]
+			& ~MAX31785_FAN_CFG_CONTROL_MODE_RPM;
+	} else if (!strcmp(buf, "rpm") || !strcmp(buf, "rpm\n")) {
+		data->fan_config[attr->index] =
+			data->fan_config[attr->index]
+			| MAX31785_FAN_CFG_CONTROL_MODE_RPM;
+	} else {
+		return -EINVAL;
+	}
+
+	mutex_lock(&data->device_lock);
+
+	if (data->fan_command[attr->index] == 0xffff)
+		err = max31785_write_fan_data(client, attr->index,
+					MAX31785_REG_FAN_COMMAND_1,
+					data->fan_command[attr->index], 0);
+	else
+		err = max31785_write_fan_data(client, attr->index,
+					MAX31785_REG_FAN_CONFIG_1_2,
+					data->fan_config[attr->index], 1);
+
+	mutex_unlock(&data->device_lock);
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static ssize_t get_fan_fault(struct device *dev,
+			     struct device_attribute *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct max31785_data *data = max31785_update_device(dev);
+	int fault;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	fault = !!(data->fault_status[attr->index]
+			& MAX31785_FAN_STATUS_FAULT_MASK);
+
+	return sprintf(buf, "%d\n", fault);
+}
+
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
+static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
+static SENSOR_DEVICE_ATTR(fan5_input, S_IRUGO, get_fan, NULL, 4);
+static SENSOR_DEVICE_ATTR(fan6_input, S_IRUGO, get_fan, NULL, 5);
+
+static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_fan_fault, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_fault, S_IRUGO, get_fan_fault, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan3_fault, S_IRUGO, get_fan_fault, NULL, 2);
+static SENSOR_DEVICE_ATTR(fan4_fault, S_IRUGO, get_fan_fault, NULL, 3);
+static SENSOR_DEVICE_ATTR(fan5_fault, S_IRUGO, get_fan_fault, NULL, 4);
+static SENSOR_DEVICE_ATTR(fan6_fault, S_IRUGO, get_fan_fault, NULL, 5);
+
+static SENSOR_DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 0);
+static SENSOR_DEVICE_ATTR(fan2_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 1);
+static SENSOR_DEVICE_ATTR(fan3_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 2);
+static SENSOR_DEVICE_ATTR(fan4_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 3);
+static SENSOR_DEVICE_ATTR(fan5_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 4);
+static SENSOR_DEVICE_ATTR(fan6_target, S_IWUSR | S_IRUGO,
+		get_fan_target, set_fan_target, 5);
+
+static SENSOR_DEVICE_ATTR(fan1_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 0);
+static SENSOR_DEVICE_ATTR(fan2_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 1);
+static SENSOR_DEVICE_ATTR(fan3_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 2);
+static SENSOR_DEVICE_ATTR(fan4_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 3);
+static SENSOR_DEVICE_ATTR(fan5_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 4);
+static SENSOR_DEVICE_ATTR(fan6_control_mode, S_IWUSR | S_IRUGO,
+		get_control_mode, set_control_mode, 5);
+
+static SENSOR_DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 0);
+static SENSOR_DEVICE_ATTR(pwm2, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 1);
+static SENSOR_DEVICE_ATTR(pwm3, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 2);
+static SENSOR_DEVICE_ATTR(pwm4, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 3);
+static SENSOR_DEVICE_ATTR(pwm5, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 4);
+static SENSOR_DEVICE_ATTR(pwm6, S_IWUSR | S_IRUGO, get_pwm, set_pwm, 5);
+
+static SENSOR_DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 0);
+static SENSOR_DEVICE_ATTR(pwm2_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 1);
+static SENSOR_DEVICE_ATTR(pwm3_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 2);
+static SENSOR_DEVICE_ATTR(pwm4_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 3);
+static SENSOR_DEVICE_ATTR(pwm5_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 4);
+static SENSOR_DEVICE_ATTR(pwm6_enable, S_IWUSR | S_IRUGO,
+		get_pwm_enable, set_pwm_enable, 5);
+
+static struct attribute *max31785_attrs[] = {
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
+	&sensor_dev_attr_fan2_input.dev_attr.attr,
+	&sensor_dev_attr_fan3_input.dev_attr.attr,
+	&sensor_dev_attr_fan4_input.dev_attr.attr,
+	&sensor_dev_attr_fan5_input.dev_attr.attr,
+	&sensor_dev_attr_fan6_input.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_fault.dev_attr.attr,
+	&sensor_dev_attr_fan2_fault.dev_attr.attr,
+	&sensor_dev_attr_fan3_fault.dev_attr.attr,
+	&sensor_dev_attr_fan4_fault.dev_attr.attr,
+	&sensor_dev_attr_fan5_fault.dev_attr.attr,
+	&sensor_dev_attr_fan6_fault.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_target.dev_attr.attr,
+	&sensor_dev_attr_fan2_target.dev_attr.attr,
+	&sensor_dev_attr_fan3_target.dev_attr.attr,
+	&sensor_dev_attr_fan4_target.dev_attr.attr,
+	&sensor_dev_attr_fan5_target.dev_attr.attr,
+	&sensor_dev_attr_fan6_target.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_control_mode.dev_attr.attr,
+	&sensor_dev_attr_fan2_control_mode.dev_attr.attr,
+	&sensor_dev_attr_fan3_control_mode.dev_attr.attr,
+	&sensor_dev_attr_fan4_control_mode.dev_attr.attr,
+	&sensor_dev_attr_fan5_control_mode.dev_attr.attr,
+	&sensor_dev_attr_fan6_control_mode.dev_attr.attr,
+
+	&sensor_dev_attr_pwm1.dev_attr.attr,
+	&sensor_dev_attr_pwm2.dev_attr.attr,
+	&sensor_dev_attr_pwm3.dev_attr.attr,
+	&sensor_dev_attr_pwm4.dev_attr.attr,
+	&sensor_dev_attr_pwm5.dev_attr.attr,
+	&sensor_dev_attr_pwm6.dev_attr.attr,
+
+	&sensor_dev_attr_pwm1_enable.dev_attr.attr,
+	&sensor_dev_attr_pwm2_enable.dev_attr.attr,
+	&sensor_dev_attr_pwm3_enable.dev_attr.attr,
+	&sensor_dev_attr_pwm4_enable.dev_attr.attr,
+	&sensor_dev_attr_pwm5_enable.dev_attr.attr,
+	&sensor_dev_attr_pwm6_enable.dev_attr.attr,
+	NULL
+};
+
+static umode_t max31785_attrs_visible(struct kobject *kobj,
+				     struct attribute *a, int n)
+{
+	return a->mode;
+}
+
+static const struct attribute_group max31785_group = {
+	.attrs = max31785_attrs,
+	.is_visible = max31785_attrs_visible,

drivers/hwmon/max31785.c line 583

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+};
+__ATTRIBUTE_GROUPS(max31785);
+
+static int max31785_init_client(struct i2c_client *client,
+				struct max31785_data *data)
+{
+	int i, rv;
+
+	dev_info(&client->dev, "Reading device state\n");
+

Noise; please drop.

drivers/hwmon/max31785.c line 585

Quoted 2 lines

drivers/hwmon/max31785.c new file +2 -0
+	mutex_lock(&data->device_lock);
+

This is only called from probe; setting the mutex is unnecessary.

Quoted 17 lines

drivers/hwmon/max31785.c new file +17 -0

+	for (i = 0; i < NR_CHANNEL; i++) {
+		rv = max31785_read_fan_data(client, i,
+				MAX31785_REG_FAN_CONFIG_1_2, 1);
+		if (rv < 0)
+			goto abort;
+		data->fan_config[i] = rv;
+
+		rv = max31785_read_fan_data(client, i,
+				MAX31785_REG_FAN_COMMAND_1, 0);
+		if (rv < 0)
+			goto abort;
+		data->fan_command[i] = rv;
+
+		rv = max31785_read_fan_data(client, i,
+				MAX31785_REG_MFR_FAN_CONFIG, 1);
+		if (rv < 0)
+			goto abort;

drivers/hwmon/max31785.c line 612

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+		data->mfr_fan_config[i] = rv;
+
+		if (!((data->fan_config[i]
+			& MAX31785_FAN_CFG_CONTROL_MODE_RPM)
+			|| is_automatic_control_mode(data, i))) {
+			data->pwm[i] = 0;
+		}
+	}
+
+	dev_info(&client->dev, "Driver initialized\n");

Noise; please drop.

Quoted 9 lines

drivers/hwmon/max31785.c new file +9 -0

+
+abort:
+	mutex_unlock(&data->device_lock);
+	return rv;
+}
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int max31785_detect(struct i2c_client *client,
+			  struct i2c_board_info *info)

drivers/hwmon/max31785.c line 631

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+{
+	struct i2c_adapter *adapter = client->adapter;
+	int rv, manufacturer, model;
+
+	if (!i2c_check_functionality(adapter,
+			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	 dev_info(&adapter->dev, "Probing for MAX31785\n");
+

Moise; please drop.

drivers/hwmon/max31785.c line 636

Quoted 5 lines

drivers/hwmon/max31785.c new file +5 -0

+	/* Probe manufacturer / model registers */
+	rv = i2c_smbus_read_byte_data(client, MAX31785_REG_MFR_ID);
+	if (rv < 0)
+		return -ENODEV;
+	manufacturer = rv;

The manufacturer variable is unnecessary. Also see below.

	rv = i2c_smbus_read_byte_data(client, MAX31785_REG_MFR_ID);
	if (rv < 0 || rv != 0x4d)
		return -ENODEV;

Quoted 6 lines

drivers/hwmon/max31785.c new file +6 -0

+
+	rv = i2c_smbus_read_byte_data(client, MAX31785_REG_MFR_MODEL);
+	if (rv < 0)
+		return -ENODEV;
+	model = rv;
+

drivers/hwmon/max31785.c line 652

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+	if (manufacturer != 0x4d)
+		return -ENODEV;
+	if (model != 0x53)
+		return -ENODEV;
+
+	dev_info(&adapter->dev,
+		"Detected MAX31785 at %d,0x%02x with"
+		" MANUFACTURER: 0x%02x MODEL: %02x\n",
+		i2c_adapter_id(client->adapter), client->addr,
+		manufacturer, model);

Output of manufacturer and model is unnecessary. It will always be 0x4d and 0x53.

Quoted 26 lines

drivers/hwmon/max31785.c new file +26 -0

+
+	strlcpy(info->type, "max31785", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static int max31785_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct max31785_data *data;
+	struct device *hwmon_dev;
+	int err;
+
+	if (!i2c_check_functionality(adapter,
+			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(dev, sizeof(struct max31785_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	mutex_init(&data->device_lock);
+

drivers/hwmon/max31785.c line 688

Quoted 10 lines

drivers/hwmon/max31785.c new file +10 -0

+	/*
+	 * Initialize the max31785 chip
+	 */
+	err = max31785_init_client(client, data);
+	if (err)
+		return err;
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
+			client->name, data, max31785_groups);
+

As mentioned above, please try using devm_hwmon_device_register_with_info(). You'll find the documentation and some converted drivers in -next.

Quoted 32 lines

drivers/hwmon/max31785.c new file +25 -0

+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max31785_id[] = {
+	{ "max31785", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max31785_id);
+
+static struct i2c_driver max31785_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.probe		= max31785_probe,
+	.driver = {
+		.name	= "max31785",
+	},
+	.id_table	= max31785_id,
+	.detect		= max31785_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(max31785_driver);
+
+MODULE_AUTHOR("Timothy Pearson <[email protected]>");
+MODULE_DESCRIPTION("MAX31785 sensor driver");
+MODULE_LICENSE("GPL");

Signature · 6 lines

1.7.9.5

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Timothy Pearson

2016-09-19 18:14 UTC #1 lore raw

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Quoted 11 lines · Guenter Roeck

Quoted 7 lines · Timothy Pearson
Add a basic driver for the MAX31785, focusing on the fan control features but ignoring the temperature and voltage monitoring features of the device.
This driver supports all fan control modes and tachometer / PWM readback where applicable.
Could you try using hwmon_device_register_with_info() as available in linux-next ? Hopefully that should reduce driver size (and give the new API some test coverage).

Ordinarily I'd be willing to try this, but in this case I wouldn't be able to test the module on real hardware; it's an embedded system and uses the 4.7 kernel at the moment. Would you be OK with merging a fixed version of this patch and I can throw together an untested variant using hwmon_device_register_with_info() for future work?

Quoted 8 lines

Please run the patch through checkpatch --strict. I don't expect you to fix all the problems is reports, but the following should be addressed.
CHECK: Prefer kernel type 'u8' over 'uint8_t'
CHECK: Prefer kernel type 'u16' over 'uint16_t'
CHECK: Alignment should match open parenthesis
CHECK: Logical continuations should be on the previous line
WARNING: quoted string split across lines

My fault, I completely forgot to run checkpatch. I'll get a V2 together shortly including addressing the inline comments.

- --
Timothy Pearson
Raptor Engineering
+1 (415) 727-8645 (direct line)
+1 (512) 690-0200 (switchboard)
https://www.raptorengineering.com
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Guenter Roeck

author maintainer

2016-09-19 20:05 UTC #2 lore raw

Quoted 13 lines · Timothy Pearson

Quoted 11 lines · Guenter Roeck
Quoted 7 lines · Timothy Pearson
Add a basic driver for the MAX31785, focusing on the fan control features but ignoring the temperature and voltage monitoring features of the device.
This driver supports all fan control modes and tachometer / PWM readback where applicable.
Could you try using hwmon_device_register_with_info() as available in linux-next ? Hopefully that should reduce driver size (and give the new API some test coverage).

Quoted 6 lines

Ordinarily I'd be willing to try this, but in this case I wouldn't be able to test the module on real hardware; it's an embedded system and uses the 4.7 kernel at the moment. Would you be OK with merging a fixed version of this patch and I can throw together an untested variant using hwmon_device_register_with_info() for future work?

After actually looking into the datasheet, I must admit that I don't understand why you did not model this as a PMBus driver.

Guenter

Timothy Pearson

2016-09-19 18:40 UTC #3 lore raw

In reply to Guenter Roeck

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Hash: SHA1

Quoted 10 lines · Guenter Roeck

Review

Quoted 7 lines

(quoted diff) +7 -0

+Sysfs entries
+-------------
+
+fan[1-6]_input           RO  fan tachometer speed in RPM
+fan[1-6]_fault           RO  fan experienced fault
+fan[1-6]_target          RW  desired fan speed in RPM
+fan[1-6]_control_mode    RW  desired control mode: rpm, pwm, or auto

Please use pwm[]_enable (see API)

Quoted 6 lines

Quoted 1 line
+pwm[1-6]_enable RW output enabled, 0=disabled, 1=enabled
Per API: 0 = no fan speed control (full speed), 1 = manual fan speed control enabled (using pwm[1-*]), 2+: automatic fan speed control
Quoted 1 line
+pwm[1-6] RW fan target duty cycle (0-255)

This particular device has a per-output PWM disable bit. How should this be handled? I don't want to globally enable outputs that are not connector or may possibly be incorrectly connected depending on hardware design.

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Guenter Roeck

author maintainer

2016-09-19 20:04 UTC #4 lore raw

Quoted 16 lines · Timothy Pearson

Quoted 15 lines · Guenter Roeck
Review
Quoted 7 lines
(quoted diff) +7 -0
+Sysfs entries
+-------------
+
+fan[1-6]_input           RO  fan tachometer speed in RPM
+fan[1-6]_fault           RO  fan experienced fault
+fan[1-6]_target          RW  desired fan speed in RPM
+fan[1-6]_control_mode    RW  desired control mode: rpm, pwm, or auto
Please use pwm[]_enable (see API)
Quoted 1 line
+pwm[1-6]_enable RW output enabled, 0=disabled, 1=enabled
Per API: 0 = no fan speed control (full speed), 1 = manual fan speed control enabled (using pwm[1-*]), 2+: automatic fan speed control

Quoted 7 lines

Quoted 1 line
Quoted 1 line
+pwm[1-6] RW fan target duty cycle (0-255)
This particular device has a per-output PWM disable bit. How should this be handled? I don't want to globally enable outputs that are not connector or may possibly be incorrectly connected depending on hardware design.

Not sure I understand. pwm[1-6]_enable = 0 means no fan speed control. Do you mean the (full speed) comment ?

Having said that, looking into the datasheet, I see that this is actually a PMBus device. Why don't you just write a PMBus extension driver for it ? AFAICS drivers/hwmon/pmbus/max34440.c would come pretty close and could possibly even be extended to support this chip.

Guenter

Timothy Pearson

2016-09-19 20:31 UTC #5 lore raw

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Hash: SHA1

Quoted 3 lines · Guenter Roeck

On Mon, Sep 19, 2016 at 01:40:36PM -0500, Timothy Pearson wrote:
Not sure I understand. pwm[1-6]_enable = 0 means no fan speed control. Do you mean the (full speed) comment ?

"no fan speed control (i.e. fan at full speed)". What I would like to see is "fan disabled (PWM turned off)".

Is that an acceptable use of the "0" value?

Quoted 6 lines

Having said that, looking into the datasheet, I see that this is actually a PMBus device. Why don't you just write a PMBus extension driver for it ? AFAICS drivers/hwmon/pmbus/max34440.c would come pretty close and could possibly even be extended to support this chip.
Guenter

The datasheet states that many functions are not available over PMBus. Rather than fight with potentially incomplete silicon support for PMBus it was easier to simply write this driver.

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Guenter Roeck

author maintainer

2016-09-20 00:54 UTC #6 lore raw

Quoted 15 lines · Timothy Pearson

Quoted 3 lines · Guenter Roeck
On Mon, Sep 19, 2016 at 01:40:36PM -0500, Timothy Pearson wrote:
Not sure I understand. pwm[1-6]_enable = 0 means no fan speed control. Do you mean the (full speed) comment ?
"no fan speed control (i.e. fan at full speed)". What I would like to see is "fan disabled (PWM turned off)".
Is that an acceptable use of the "0" value?
Quoted 5 lines
Having said that, looking into the datasheet, I see that this is actually a PMBus device. Why don't you just write a PMBus extension driver for it ? AFAICS drivers/hwmon/pmbus/max34440.c would come pretty close and could possibly even be extended to support this chip.

Quoted 6 lines

Quoted 1 line
Guenter
The datasheet states that many functions are not available over PMBus. Rather than fight with potentially incomplete silicon support for PMBus it was easier to simply write this driver.

And then you are using all pmbus commands ? Seems odd.

I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.

Guenter

Quoted 6 lines

Signature · 5 lines

Timothy Pearson
Raptor Engineering
+1 (415) 727-8645 (direct line)
+1 (512) 690-0200 (switchboard)
https://www.raptorengineering.com

Timothy Pearson

2016-09-20 01:41 UTC #7 lore raw

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Quoted 9 lines · Guenter Roeck

Quoted 1 line · Timothy Pearson
On 09/19/2016 03:04 PM, Guenter Roeck wrote:
And then you are using all pmbus commands ? Seems odd.
I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.
Guenter

Well, I went back over the datasheet and I may have misinterpreted some of the introductory text. In any case I'm not likely to go back and re-do this as a pmbus driver as the original was done in my free time and works well enough for our needs at the moment. When the patch no longer applies perhaps someone else can pick up the porting effort.

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Timothy Pearson

2016-09-20 19:41 UTC #8 lore raw

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Quoted 8 lines · Guenter Roeck

Quoted 2 lines · Guenter Roeck
And then you are using all pmbus commands ? Seems odd.
I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.
Guenter

Regarding the PMBus driver, I looked over the documentation available
here: https://www.kernel.org/doc/Documentation/hwmon/pmbus

- From what I can tell PMBus drivers do not support configuring the fan control parameters, only monitoring the fan status and speed. Is this correct, and if not where would I find the correct documentation?

Thank you,

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Guenter Roeck

author maintainer

2016-09-20 19:59 UTC #9 lore raw

Quoted 8 lines · Timothy Pearson

Quoted 7 lines · Guenter Roeck
Quoted 2 lines · Guenter Roeck
And then you are using all pmbus commands ? Seems odd.
I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.

Quoted 9 lines

Quoted 1 line
Guenter
Regarding the PMBus driver, I looked over the documentation available
here: https://www.kernel.org/doc/Documentation/hwmon/pmbus
From what I can tell PMBus drivers do not support configuring the fan control parameters, only monitoring the fan status and speed. Is this correct, and if not where would I find the correct documentation?

So far that wasn't needed. That doesn't mean it can not be added.

I orderd an evaluation board and will likely spend some time on it myself after I get it.

Guenter

Timothy Pearson

2016-09-20 20:01 UTC #10 lore raw

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Quoted 18 lines · Guenter Roeck

Quoted 8 lines · Timothy Pearson
Quoted 7 lines · Guenter Roeck
Quoted 2 lines · Guenter Roeck
And then you are using all pmbus commands ? Seems odd.
I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.
Quoted 9 lines
Quoted 1 line
Guenter
Regarding the PMBus driver, I looked over the documentation available
here: https://www.kernel.org/doc/Documentation/hwmon/pmbus
From what I can tell PMBus drivers do not support configuring the fan control parameters, only monitoring the fan status and speed. Is this correct, and if not where would I find the correct documentation?

Quoted 6 lines

So far that wasn't needed. That doesn't mean it can not be added.
I orderd an evaluation board and will likely spend some time on it myself after I get it.
Guenter

OK, sounds good. I looked back in the notes for this project and we had originally considered using a PMBus driver but ran into the kernel documentation, noted the missing control features, and I subsequently misinterpreted the datasheet using the kernel docs as a reference. This is why the hwmon driver was implemented.

Please let me know if I can be of any assistance.

Thanks!

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Guenter Roeck

author maintainer

2016-09-21 03:04 UTC #11 lore raw

Quoted 24 lines · Timothy Pearson

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Quoted 20 lines · Guenter Roeck
Quoted 8 lines · Timothy Pearson
Quoted 7 lines · Guenter Roeck
Quoted 2 lines · Guenter Roeck
And then you are using all pmbus commands ? Seems odd.
I guess I'l buy an evaluation board if one is available and check if your claim is correct. I am not inclined to accept a non-pmbus driver for a pmbus device without good reason.
Quoted 9 lines
Quoted 1 line
Guenter
Regarding the PMBus driver, I looked over the documentation available
here: https://www.kernel.org/doc/Documentation/hwmon/pmbus
From what I can tell PMBus drivers do not support configuring the fan control parameters, only monitoring the fan status and speed. Is this correct, and if not where would I find the correct documentation?
So far that wasn't needed. That doesn't mean it can not be added.

Quoted 8 lines

Quoted 4 lines
I orderd an evaluation board and will likely spend some time on it myself after I get it.
Guenter
OK, sounds good. I looked back in the notes for this project and we had originally considered using a PMBus driver but ran into the kernel documentation, noted the missing control features, and I subsequently

It is always useful to talk with the maintainer.

Quoted 3 lines

misinterpreted the datasheet using the kernel docs as a reference. This is why the hwmon driver was implemented.

I am still not sure I understand what irked you off in the datasheet. Is it the "supports a subset of the commands defined in the PMBus Specfication" ? If so, please keep in mind that every single chip supporting PMBus will only support a subset of PMBus commands.

Quoted 2 lines

Please let me know if I can be of any assistance.

Sure, I'll let you know.

Thanks,
Guenter

Timothy Pearson

2016-09-21 03:09 UTC #12 lore raw

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Quoted 10 lines · Guenter Roeck

Quoted 7 lines · Timothy Pearson
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On 09/20/2016 02:59 PM, Guenter Roeck wrote:
OK, sounds good. I looked back in the notes for this project and we had originally considered using a PMBus driver but ran into the kernel documentation, noted the missing control features, and I subsequently
It is always useful to talk with the maintainer.

I'll keep that in mind next time. This particular area of the kernel seems much more responsive than some of the others that we've had the misfortune of trying to work with; multiple weeks of delay for a response to a simple two line patch tends to turn one off of the mailing lists...

Quoted 8 lines

Quoted 3 lines
misinterpreted the datasheet using the kernel docs as a reference. This is why the hwmon driver was implemented.
I am still not sure I understand what irked you off in the datasheet. Is it the "supports a subset of the commands defined in the PMBus Specfication" ? If so, please keep in mind that every single chip supporting PMBus will only support a subset of PMBus commands.

Yes, I definitely understand that now. This was the line that, when taken out of context and compared against the kernel documentation, caused an incorrect assumption on my part.

Quoted 7 lines

Quoted 2 lines
Please let me know if I can be of any assistance.
Sure, I'll let you know.
Thanks,
Guenter

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Timothy Pearson

2016-10-11 14:39 UTC #13 lore raw

In reply to Guenter Roeck

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Quoted 18 lines · Guenter Roeck

Quoted 5 lines · Timothy Pearson
On 09/20/2016 02:59 PM, Guenter Roeck wrote:
OK, sounds good. I looked back in the notes for this project and we had originally considered using a PMBus driver but ran into the kernel documentation, noted the missing control features, and I subsequently
It is always useful to talk with the maintainer.
Quoted 3 lines
misinterpreted the datasheet using the kernel docs as a reference. This is why the hwmon driver was implemented.
I am still not sure I understand what irked you off in the datasheet. Is it the "supports a subset of the commands defined in the PMBus Specfication" ? If so, please keep in mind that every single chip supporting PMBus will only support a subset of PMBus commands.

Quoted 7 lines

Quoted 2 lines
Please let me know if I can be of any assistance.
Sure, I'll let you know.
Thanks,
Guenter

Just checking back in to see how things are going with this driver. I don't really know how involved the surgery to PMBus will be to get this device working; are we looking at weeks / months or something sooner?

Thanks again!

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