hwmon: Add support for Lineage Compact Power Line PEM devices

This patch adds support for hardware monitoring of Lineage Compact Power Line
Power Entry Modules.

Reviewed-by: Tom Grennan <tom.grennan@ericsson.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

4 files changed, 678 insertions, 0 deletions

diff --git a/Documentation/hwmon/lineage-pem b/Documentation/hwmon/lineage-pem
new file mode 100644
index 0000000..2ba5ed1
--- /dev/null
+++ b/Documentation/hwmon/lineage-pem
@@ -0,0 +1,77 @@
+Kernel driver lineage-pem
+=========================
+
+Supported devices:
+  * Lineage Compact Power Line Power Entry Modules
+    Prefix: 'lineage-pem'
+    Addresses scanned: -
+    Documentation:
+        http://www.lineagepower.com/oem/pdf/CPLI2C.pdf
+
+Author: Guenter Roeck <guenter.roeck@ericsson.com>
+
+
+Description
+-----------
+
+This driver supports various Lineage Compact Power Line DC/DC and AC/DC
+converters such as CP1800, CP2000AC, CP2000DC, CP2100DC, and others.
+
+Lineage CPL power entry modules are nominally PMBus compliant. However, most
+standard PMBus commands are not supported. Specifically, all hardware monitoring
+and status reporting commands are non-standard. For this reason, a standard
+PMBus driver can not be used.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for Lineage CPL devices, since there is no register
+which can be safely used to identify the chip. You will have to instantiate
+the devices explicitly.
+
+Example: the following will load the driver for a Lineage PEM at address 0x40
+on I2C bus #1:
+$ modprobe lineage-pem
+$ echo lineage-pem 0x40 > /sys/bus/i2c/devices/i2c-1/new_device
+
+All Lineage CPL power entry modules have a built-in I2C bus master selector
+(PCA9541). To ensure device access, this driver should only be used as client
+driver to the pca9541 I2C master selector driver.
+
+
+Sysfs entries
+-------------
+
+All Lineage CPL devices report output voltage and device temperature as well as
+alarms for output voltage, temperature, input voltage, input current, input power,
+and fan status.
+
+Input voltage, input current, input power, and fan speed measurement is only
+supported on newer devices. The driver detects if those attributes are supported,
+and only creates respective sysfs entries if they are.
+
+in1_input		Output voltage (mV)
+in1_min_alarm		Output undervoltage alarm
+in1_max_alarm		Output overvoltage alarm
+in1_crit		Output voltage critical alarm
+
+in2_input		Input voltage (mV, optional)
+in2_alarm		Input voltage alarm
+
+curr1_input		Input current (mA, optional)
+curr1_alarm		Input overcurrent alarm
+
+power1_input		Input power (uW, optional)
+power1_alarm		Input power alarm
+
+fan1_input		Fan 1 speed (rpm, optional)
+fan2_input		Fan 2 speed (rpm, optional)
+fan3_input		Fan 3 speed (rpm, optional)
+
+temp1_input
+temp1_max
+temp1_crit
+temp1_alarm
+temp1_crit_alarm
+temp1_fault
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 3bd993b..d4ffc60 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -467,6 +467,17 @@ config SENSORS_JC42
 	  This driver can also be built as a module.  If so, the module
 	  will be called jc42.
 
+config SENSORS_LINEAGE
+	tristate "Lineage Compact Power Line Power Entry Module"
+	depends on I2C && EXPERIMENTAL
+	help
+	  If you say yes here you get support for the Lineage Compact Power Line
+	  series of DC/DC and AC/DC converters such as CP1800, CP2000AC,
+	  CP2000DC, CP2725, and others.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called lineage-pem.
+
 config SENSORS_LM63
 	tristate "National Semiconductor LM63 and LM64"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f697831..4681981 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
 obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o
 obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
 obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
+obj-$(CONFIG_SENSORS_LINEAGE)	+= lineage-pem.o
 obj-$(CONFIG_SENSORS_LIS3LV02D) += lis3lv02d.o hp_accel.o
 obj-$(CONFIG_SENSORS_LIS3_SPI)	+= lis3lv02d.o lis3lv02d_spi.o
 obj-$(CONFIG_SENSORS_LIS3_I2C)	+= lis3lv02d.o lis3lv02d_i2c.o
diff --git a/drivers/hwmon/lineage-pem.c b/drivers/hwmon/lineage-pem.c
new file mode 100644
index 0000000..d39ee24
--- /dev/null
+++ b/drivers/hwmon/lineage-pem.c
@@ -0,0 +1,589 @@
+/*
+ * Driver for Lineage Compact Power Line series of power entry modules.
+ *
+ * Copyright (C) 2010, 2011 Ericsson AB.
+ *
+ * Documentation:
+ *  http://www.lineagepower.com/oem/pdf/CPLI2C.pdf
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+/*
+ * This driver supports various Lineage Compact Power Line DC/DC and AC/DC
+ * converters such as CP1800, CP2000AC, CP2000DC, CP2100DC, and others.
+ *
+ * The devices are nominally PMBus compliant. However, most standard PMBus
+ * commands are not supported. Specifically, all hardware monitoring and
+ * status reporting commands are non-standard. For this reason, a standard
+ * PMBus driver can not be used.
+ *
+ * All Lineage CPL devices have a built-in I2C bus master selector (PCA9541).
+ * To ensure device access, this driver should only be used as client driver
+ * to the pca9541 I2C master selector driver.
+ */
+
+/* Command codes */
+#define PEM_OPERATION		0x01
+#define PEM_CLEAR_INFO_FLAGS	0x03
+#define PEM_VOUT_COMMAND	0x21
+#define PEM_VOUT_OV_FAULT_LIMIT	0x40
+#define PEM_READ_DATA_STRING	0xd0
+#define PEM_READ_INPUT_STRING	0xdc
+#define PEM_READ_FIRMWARE_REV	0xdd
+#define PEM_READ_RUN_TIMER	0xde
+#define PEM_FAN_HI_SPEED	0xdf
+#define PEM_FAN_NORMAL_SPEED	0xe0
+#define PEM_READ_FAN_SPEED	0xe1
+
+/* offsets in data string */
+#define PEM_DATA_STATUS_2	0
+#define PEM_DATA_STATUS_1	1
+#define PEM_DATA_ALARM_2	2
+#define PEM_DATA_ALARM_1	3
+#define PEM_DATA_VOUT_LSB	4
+#define PEM_DATA_VOUT_MSB	5
+#define PEM_DATA_CURRENT	6
+#define PEM_DATA_TEMP		7
+
+/* Virtual entries, to report constants */
+#define PEM_DATA_TEMP_MAX	10
+#define PEM_DATA_TEMP_CRIT	11
+
+/* offsets in input string */
+#define PEM_INPUT_VOLTAGE	0
+#define PEM_INPUT_POWER_LSB	1
+#define PEM_INPUT_POWER_MSB	2
+
+/* offsets in fan data */
+#define PEM_FAN_ADJUSTMENT	0
+#define PEM_FAN_FAN1		1
+#define PEM_FAN_FAN2		2
+#define PEM_FAN_FAN3		3
+
+/* Status register bits */
+#define STS1_OUTPUT_ON		(1 << 0)
+#define STS1_LEDS_FLASHING	(1 << 1)
+#define STS1_EXT_FAULT		(1 << 2)
+#define STS1_SERVICE_LED_ON	(1 << 3)
+#define STS1_SHUTDOWN_OCCURRED	(1 << 4)
+#define STS1_INT_FAULT		(1 << 5)
+#define STS1_ISOLATION_TEST_OK	(1 << 6)
+
+#define STS2_ENABLE_PIN_HI	(1 << 0)
+#define STS2_DATA_OUT_RANGE	(1 << 1)
+#define STS2_RESTARTED_OK	(1 << 1)
+#define STS2_ISOLATION_TEST_FAIL (1 << 3)
+#define STS2_HIGH_POWER_CAP	(1 << 4)
+#define STS2_INVALID_INSTR	(1 << 5)
+#define STS2_WILL_RESTART	(1 << 6)
+#define STS2_PEC_ERR		(1 << 7)
+
+/* Alarm register bits */
+#define ALRM1_VIN_OUT_LIMIT	(1 << 0)
+#define ALRM1_VOUT_OUT_LIMIT	(1 << 1)
+#define ALRM1_OV_VOLT_SHUTDOWN	(1 << 2)
+#define ALRM1_VIN_OVERCURRENT	(1 << 3)
+#define ALRM1_TEMP_WARNING	(1 << 4)
+#define ALRM1_TEMP_SHUTDOWN	(1 << 5)
+#define ALRM1_PRIMARY_FAULT	(1 << 6)
+#define ALRM1_POWER_LIMIT	(1 << 7)
+
+#define ALRM2_5V_OUT_LIMIT	(1 << 1)
+#define ALRM2_TEMP_FAULT	(1 << 2)
+#define ALRM2_OV_LOW		(1 << 3)
+#define ALRM2_DCDC_TEMP_HIGH	(1 << 4)
+#define ALRM2_PRI_TEMP_HIGH	(1 << 5)
+#define ALRM2_NO_PRIMARY	(1 << 6)
+#define ALRM2_FAN_FAULT		(1 << 7)
+
+#define FIRMWARE_REV_LEN	4
+#define DATA_STRING_LEN		9
+#define INPUT_STRING_LEN	5	/* 4 for most devices	*/
+#define FAN_SPEED_LEN		5
+
+struct pem_data {
+	struct device *hwmon_dev;
+
+	struct mutex update_lock;
+	bool valid;
+	bool fans_supported;
+	int input_length;
+	unsigned long last_updated;	/* in jiffies */
+
+	u8 firmware_rev[FIRMWARE_REV_LEN];
+	u8 data_string[DATA_STRING_LEN];
+	u8 input_string[INPUT_STRING_LEN];
+	u8 fan_speed[FAN_SPEED_LEN];
+};
+
+static int pem_read_block(struct i2c_client *client, u8 command, u8 *data,
+			  int data_len)
+{
+	u8 block_buffer[I2C_SMBUS_BLOCK_MAX];
+	int result;
+
+	result = i2c_smbus_read_block_data(client, command, block_buffer);
+	if (unlikely(result < 0))
+		goto abort;
+	if (unlikely(result == 0xff || result != data_len)) {
+		result = -EIO;
+		goto abort;
+	}
+	memcpy(data, block_buffer, data_len);
+	result = 0;
+abort:
+	return result;
+}
+
+static struct pem_data *pem_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pem_data *data = i2c_get_clientdata(client);
+	struct pem_data *ret = data;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+		int result;
+
+		/* Read data string */
+		result = pem_read_block(client, PEM_READ_DATA_STRING,
+					data->data_string,
+					sizeof(data->data_string));
+		if (unlikely(result < 0)) {
+			ret = ERR_PTR(result);
+			goto abort;
+		}
+
+		/* Read input string */
+		if (data->input_length) {
+			result = pem_read_block(client, PEM_READ_INPUT_STRING,
+						data->input_string,
+						data->input_length);
+			if (unlikely(result < 0)) {
+				ret = ERR_PTR(result);
+				goto abort;
+			}
+		}
+
+		/* Read fan speeds */
+		if (data->fans_supported) {
+			result = pem_read_block(client, PEM_READ_FAN_SPEED,
+						data->fan_speed,
+						sizeof(data->fan_speed));
+			if (unlikely(result < 0)) {
+				ret = ERR_PTR(result);
+				goto abort;
+			}
+		}
+
+		i2c_smbus_write_byte(client, PEM_CLEAR_INFO_FLAGS);
+
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static long pem_get_data(u8 *data, int len, int index)
+{
+	long val;
+
+	switch (index) {
+	case PEM_DATA_VOUT_LSB:
+		val = (data[index] + (data[index+1] << 8)) * 5 / 2;
+		break;
+	case PEM_DATA_CURRENT:
+		val = data[index] * 200;
+		break;
+	case PEM_DATA_TEMP:
+		val = data[index] * 1000;
+		break;
+	case PEM_DATA_TEMP_MAX:
+		val = 97 * 1000;	/* 97 degrees C per datasheet */
+		break;
+	case PEM_DATA_TEMP_CRIT:
+		val = 107 * 1000;	/* 107 degrees C per datasheet */
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		val = 0;
+	}
+	return val;
+}
+
+static long pem_get_input(u8 *data, int len, int index)
+{
+	long val;
+
+	switch (index) {
+	case PEM_INPUT_VOLTAGE:
+		if (len == INPUT_STRING_LEN)
+			val = (data[index] + (data[index+1] << 8) - 75) * 1000;
+		else
+			val = (data[index] - 75) * 1000;
+		break;
+	case PEM_INPUT_POWER_LSB:
+		if (len == INPUT_STRING_LEN)
+			index++;
+		val = (data[index] + (data[index+1] << 8)) * 1000000L;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		val = 0;
+	}
+	return val;
+}
+
+static long pem_get_fan(u8 *data, int len, int index)
+{
+	long val;
+
+	switch (index) {
+	case PEM_FAN_FAN1:
+	case PEM_FAN_FAN2:
+	case PEM_FAN_FAN3:
+		val = data[index] * 100;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		val = 0;
+	}
+	return val;
+}
+
+/*
+ * Show boolean, either a fault or an alarm.
+ * .nr points to the register, .index is the bit mask to check
+ */
+static ssize_t pem_show_bool(struct device *dev,
+			     struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
+	struct pem_data *data = pem_update_device(dev);
+	u8 status;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	status = data->data_string[attr->nr] & attr->index;
+	return snprintf(buf, PAGE_SIZE, "%d\n", !!status);
+}
+
+static ssize_t pem_show_data(struct device *dev, struct device_attribute *da,
+			     char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct pem_data *data = pem_update_device(dev);
+	long value;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	value = pem_get_data(data->data_string, sizeof(data->data_string),
+			     attr->index);
+
+	return snprintf(buf, PAGE_SIZE, "%ld\n", value);
+}
+
+static ssize_t pem_show_input(struct device *dev, struct device_attribute *da,
+			      char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct pem_data *data = pem_update_device(dev);
+	long value;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	value = pem_get_input(data->input_string, sizeof(data->input_string),
+			      attr->index);
+
+	return snprintf(buf, PAGE_SIZE, "%ld\n", value);
+}
+
+static ssize_t pem_show_fan(struct device *dev, struct device_attribute *da,
+			    char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct pem_data *data = pem_update_device(dev);
+	long value;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	value = pem_get_fan(data->fan_speed, sizeof(data->fan_speed),
+			    attr->index);
+
+	return snprintf(buf, PAGE_SIZE, "%ld\n", value);
+}
+
+/* Voltages */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, pem_show_data, NULL,
+			  PEM_DATA_VOUT_LSB);
+static SENSOR_DEVICE_ATTR_2(in1_min_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_2, ALRM2_OV_LOW);
+static SENSOR_DEVICE_ATTR_2(in1_max_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_VOUT_OUT_LIMIT);
+static SENSOR_DEVICE_ATTR_2(in1_crit_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_OV_VOLT_SHUTDOWN);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, pem_show_input, NULL,
+			  PEM_INPUT_VOLTAGE);
+static SENSOR_DEVICE_ATTR_2(in2_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1,
+			    ALRM1_VIN_OUT_LIMIT | ALRM1_PRIMARY_FAULT);
+
+/* Currents */
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, pem_show_data, NULL,
+			  PEM_DATA_CURRENT);
+static SENSOR_DEVICE_ATTR_2(curr1_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_VIN_OVERCURRENT);
+
+/* Power */
+static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, pem_show_input, NULL,
+			  PEM_INPUT_POWER_LSB);
+static SENSOR_DEVICE_ATTR_2(power1_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_POWER_LIMIT);
+
+/* Fans */
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, pem_show_fan, NULL,
+			  PEM_FAN_FAN1);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, pem_show_fan, NULL,
+			  PEM_FAN_FAN2);
+static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, pem_show_fan, NULL,
+			  PEM_FAN_FAN3);
+static SENSOR_DEVICE_ATTR_2(fan1_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_2, ALRM2_FAN_FAULT);
+
+/* Temperatures */
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, pem_show_data, NULL,
+			  PEM_DATA_TEMP);
+static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO, pem_show_data, NULL,
+			  PEM_DATA_TEMP_MAX);
+static SENSOR_DEVICE_ATTR(temp1_crit, S_IRUGO, pem_show_data, NULL,
+			  PEM_DATA_TEMP_CRIT);
+static SENSOR_DEVICE_ATTR_2(temp1_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_TEMP_WARNING);
+static SENSOR_DEVICE_ATTR_2(temp1_crit_alarm, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_1, ALRM1_TEMP_SHUTDOWN);
+static SENSOR_DEVICE_ATTR_2(temp1_fault, S_IRUGO, pem_show_bool, NULL,
+			    PEM_DATA_ALARM_2, ALRM2_TEMP_FAULT);
+
+static struct attribute *pem_attributes[] = {
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_in2_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_curr1_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_power1_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp1_max.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit.dev_attr.attr,
+	&sensor_dev_attr_temp1_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_fault.dev_attr.attr,
+
+	NULL,
+};
+
+static const struct attribute_group pem_group = {
+	.attrs = pem_attributes,
+};
+
+static struct attribute *pem_input_attributes[] = {
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+	&sensor_dev_attr_power1_input.dev_attr.attr,
+};
+
+static const struct attribute_group pem_input_group = {
+	.attrs = pem_input_attributes,
+};
+
+static struct attribute *pem_fan_attributes[] = {
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
+	&sensor_dev_attr_fan2_input.dev_attr.attr,
+	&sensor_dev_attr_fan3_input.dev_attr.attr,
+};
+
+static const struct attribute_group pem_fan_group = {
+	.attrs = pem_fan_attributes,
+};
+
+static int pem_probe(struct i2c_client *client,
+		     const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct pem_data *data;
+	int ret;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BLOCK_DATA
+				     | I2C_FUNC_SMBUS_WRITE_BYTE))
+		return -ENODEV;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	/*
+	 * We use the next two commands to determine if the device is really
+	 * there.
+	 */
+	ret = pem_read_block(client, PEM_READ_FIRMWARE_REV,
+			     data->firmware_rev, sizeof(data->firmware_rev));
+	if (ret < 0)
+		goto out_kfree;
+
+	ret = i2c_smbus_write_byte(client, PEM_CLEAR_INFO_FLAGS);
+	if (ret < 0)
+		goto out_kfree;
+
+	dev_info(&client->dev, "Firmware revision %d.%d.%d\n",
+		 data->firmware_rev[0], data->firmware_rev[1],
+		 data->firmware_rev[2]);
+
+	/* Register sysfs hooks */
+	ret = sysfs_create_group(&client->dev.kobj, &pem_group);
+	if (ret)
+		goto out_kfree;
+
+	/*
+	 * Check if input readings are supported.
+	 * This is the case if we can read input data,
+	 * and if the returned data is not all zeros.
+	 * Note that input alarms are always supported.
+	 */
+	ret = pem_read_block(client, PEM_READ_INPUT_STRING,
+			     data->input_string,
+			     sizeof(data->input_string) - 1);
+	if (!ret && (data->input_string[0] || data->input_string[1] ||
+		     data->input_string[2]))
+		data->input_length = sizeof(data->input_string) - 1;
+	else if (ret < 0) {
+		/* Input string is one byte longer for some devices */
+		ret = pem_read_block(client, PEM_READ_INPUT_STRING,
+				    data->input_string,
+				    sizeof(data->input_string));
+		if (!ret && (data->input_string[0] || data->input_string[1] ||
+			    data->input_string[2] || data->input_string[3]))
+			data->input_length = sizeof(data->input_string);
+	}
+	ret = 0;
+	if (data->input_length) {
+		ret = sysfs_create_group(&client->dev.kobj, &pem_input_group);
+		if (ret)
+			goto out_remove_groups;
+	}
+
+	/*
+	 * Check if fan speed readings are supported.
+	 * This is the case if we can read fan speed data,
+	 * and if the returned data is not all zeros.
+	 * Note that the fan alarm is always supported.
+	 */
+	ret = pem_read_block(client, PEM_READ_FAN_SPEED,
+			     data->fan_speed,
+			     sizeof(data->fan_speed));
+	if (!ret && (data->fan_speed[0] || data->fan_speed[1] ||
+		     data->fan_speed[2] || data->fan_speed[3])) {
+		data->fans_supported = true;
+		ret = sysfs_create_group(&client->dev.kobj, &pem_fan_group);
+		if (ret)
+			goto out_remove_groups;
+	}
+
+	data->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		ret = PTR_ERR(data->hwmon_dev);
+		goto out_remove_groups;
+	}
+
+	return 0;
+
+out_remove_groups:
+	sysfs_remove_group(&client->dev.kobj, &pem_input_group);
+	sysfs_remove_group(&client->dev.kobj, &pem_fan_group);
+	sysfs_remove_group(&client->dev.kobj, &pem_group);
+out_kfree:
+	kfree(data);
+	return ret;
+}
+
+static int pem_remove(struct i2c_client *client)
+{
+	struct pem_data *data = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(data->hwmon_dev);
+
+	sysfs_remove_group(&client->dev.kobj, &pem_input_group);
+	sysfs_remove_group(&client->dev.kobj, &pem_fan_group);
+	sysfs_remove_group(&client->dev.kobj, &pem_group);
+
+	kfree(data);
+	return 0;
+}
+
+static const struct i2c_device_id pem_id[] = {
+	{"lineage_pem", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, pem_id);
+
+static struct i2c_driver pem_driver = {
+	.driver = {
+		   .name = "lineage_pem",
+		   },
+	.probe = pem_probe,
+	.remove = pem_remove,
+	.id_table = pem_id,
+};
+
+static int __init pem_init(void)
+{
+	return i2c_add_driver(&pem_driver);
+}
+
+static void __exit pem_exit(void)
+{
+	i2c_del_driver(&pem_driver);
+}
+
+MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
+MODULE_DESCRIPTION("Lineage CPL PEM hardware monitoring driver");
+MODULE_LICENSE("GPL");
+
+module_init(pem_init);
+module_exit(pem_exit);