hwmon: Add support for Lattice's POWR1220 power manager IC

This patch adds support for Lattice's POWR1220 power manager IC. Read
access to all the ADCs on the chip are supported through the hwmon
sysfs files.

Signed-off-by: Scott Kanowitz <[e-mail]>
[Guenter Roeck: Removed some extra ( )]
Signed-off-by: Guenter Roeck <[e-mail]>

Documentation/hwmon/powr1220

···
+Kernel driver powr1220
+==================
+
+Supported chips:
+  * Lattice POWR1220AT8
+    Prefix: 'powr1220'
+    Addresses scanned: none
+    Datasheet: Publicly available at the Lattice website
+               http://www.latticesemi.com/
+
+Author: Scott Kanowitz <[e-mail]>
+
+Description
+-----------
+
+This driver supports the Lattice POWR1220AT8 chip. The POWR1220
+includes voltage monitoring for 14 inputs as well as trim settings
+for output voltages and GPIOs. This driver implements the voltage
+monitoring portion of the chip.
+
+Voltages are sampled by a 12-bit ADC with a step size of 2 mV.
+An in-line attenuator allows measurements from 0 to 6 V. The
+attenuator is enabled or disabled depending on the setting of the
+input's max value. The driver will enable the attenuator for any
+value over the low measurement range maximum of 2 V.
+
+The input naming convention is as follows:
+
+driver name    pin name
+in0            VMON1
+in1            VMON2
+in2            VMON3
+in2            VMON4
+in4            VMON5
+in5            VMON6
+in6            VMON7
+in7            VMON8
+in8            VMON9
+in9            VMON10
+in10           VMON11
+in11           VMON12
+in12           VCCA
+in13           VCCINP
+
+The ADC readings are updated on request with a minimum period of 1s.

drivers/hwmon/Kconfig

···
 	  This driver can also be built as a module.  If so, the module
 	  will be called jc42.
 
+config SENSORS_POWR1220
+	tristate "Lattice POWR1220 Power Monitoring"
+	depends on I2C
+	default n
+	help
+	  If you say yes here you get access to the hardware monitoring
+	  functions of the Lattice POWR1220 isp Power Supply Monitoring,
+	  Sequencing and Margining Controller.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called powr1220.
+
 config SENSORS_LINEAGE
 	tristate "Lineage Compact Power Line Power Entry Module"
 	depends on I2C

drivers/hwmon/Makefile

···
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
 obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
+obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o

drivers/hwmon/powr1220.c

···
+/*
+ * powr1220.c - Driver for the Lattice POWR1220 programmable power supply
+ * and monitor. Users can read all ADC inputs along with their labels
+ * using the sysfs nodes.
+ *
+ * Copyright (c) 2014 Echo360 http://www.echo360.com
+ * Scott Kanowitz <[e-mail]> <[e-mail]>
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+
+#define ADC_STEP_MV			2
+#define ADC_MAX_LOW_MEASUREMENT_MV	2000
+
+enum powr1220_regs {
+	VMON_STATUS0,
+	VMON_STATUS1,
+	VMON_STATUS2,
+	OUTPUT_STATUS0,
+	OUTPUT_STATUS1,
+	OUTPUT_STATUS2,
+	INPUT_STATUS,
+	ADC_VALUE_LOW,
+	ADC_VALUE_HIGH,
+	ADC_MUX,
+	UES_BYTE0,
+	UES_BYTE1,
+	UES_BYTE2,
+	UES_BYTE3,
+	GP_OUTPUT1,
+	GP_OUTPUT2,
+	GP_OUTPUT3,
+	INPUT_VALUE,
+	RESET,
+	TRIM1_TRIM,
+	TRIM2_TRIM,
+	TRIM3_TRIM,
+	TRIM4_TRIM,
+	TRIM5_TRIM,
+	TRIM6_TRIM,
+	TRIM7_TRIM,
+	TRIM8_TRIM,
+	MAX_POWR1220_REGS
+};
+
+enum powr1220_adc_values {
+	VMON1,
+	VMON2,
+	VMON3,
+	VMON4,
+	VMON5,
+	VMON6,
+	VMON7,
+	VMON8,
+	VMON9,
+	VMON10,
+	VMON11,
+	VMON12,
+	VCCA,
+	VCCINP,
+	MAX_POWR1220_ADC_VALUES
+};
+
+struct powr1220_data {
+	struct i2c_client *client;
+	struct mutex update_lock;
+	bool adc_valid[MAX_POWR1220_ADC_VALUES];
+	 /* the next value is in jiffies */
+	unsigned long adc_last_updated[MAX_POWR1220_ADC_VALUES];
+
+	/* values */
+	int adc_maxes[MAX_POWR1220_ADC_VALUES];
+	int adc_values[MAX_POWR1220_ADC_VALUES];
+};
+
+static const char * const input_names[] = {
+	[VMON1]    = "vmon1",
+	[VMON2]    = "vmon2",
+	[VMON3]    = "vmon3",
+	[VMON4]    = "vmon4",
+	[VMON5]    = "vmon5",
+	[VMON6]    = "vmon6",
+	[VMON7]    = "vmon7",
+	[VMON8]    = "vmon8",
+	[VMON9]    = "vmon9",
+	[VMON10]   = "vmon10",
+	[VMON11]   = "vmon11",
+	[VMON12]   = "vmon12",
+	[VCCA]     = "vcca",
+	[VCCINP]   = "vccinp",
+};
+
+/* Reads the specified ADC channel */
+static int powr1220_read_adc(struct device *dev, int ch_num)
+{
+	struct powr1220_data *data = dev_get_drvdata(dev);
+	int reading;
+	int result;
+	int adc_range = 0;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->adc_last_updated[ch_num] + HZ) ||
+			!data->adc_valid[ch_num]) {
+		/*
+		 * figure out if we need to use the attenuator for
+		 * high inputs or inputs that we don't yet have a measurement
+		 * for. We dynamically set the attenuator depending on the
+		 * max reading.
+		 */
+		if (data->adc_maxes[ch_num] > ADC_MAX_LOW_MEASUREMENT_MV ||
+				data->adc_maxes[ch_num] == 0)
+			adc_range = 1 << 4;
+
+		/* set the attenuator and mux */
+		result = i2c_smbus_write_byte_data(data->client, ADC_MUX,
+				adc_range | ch_num);
+		if (result)
+			goto exit;
+
+		/*
+		 * wait at least Tconvert time (200 us) for the
+		 * conversion to complete
+		 */
+		udelay(200);
+
+		/* get the ADC reading */
+		result = i2c_smbus_read_byte_data(data->client, ADC_VALUE_LOW);
+		if (result < 0)
+			goto exit;
+
+		reading = result >> 4;
+
+		/* get the upper half of the reading */
+		result = i2c_smbus_read_byte_data(data->client, ADC_VALUE_HIGH);
+		if (result < 0)
+			goto exit;
+
+		reading |= result << 4;
+
+		/* now convert the reading to a voltage */
+		reading *= ADC_STEP_MV;
+		data->adc_values[ch_num] = reading;
+		data->adc_valid[ch_num] = true;
+		data->adc_last_updated[ch_num] = jiffies;
+		result = reading;
+
+		if (reading > data->adc_maxes[ch_num])
+			data->adc_maxes[ch_num] = reading;
+	} else {
+		result = data->adc_values[ch_num];
+	}
+
+exit:
+	mutex_unlock(&data->update_lock);
+
+	return result;
+}
+
+/* Shows the voltage associated with the specified ADC channel */
+static ssize_t powr1220_show_voltage(struct device *dev,
+	struct device_attribute *dev_attr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	int adc_val = powr1220_read_adc(dev, attr->index);
+
+	if (adc_val < 0)
+		return adc_val;
+
+	return sprintf(buf, "%d\n", adc_val);
+}
+
+/* Shows the maximum setting associated with the specified ADC channel */
+static ssize_t powr1220_show_max(struct device *dev,
+	struct device_attribute *dev_attr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	struct powr1220_data *data = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", data->adc_maxes[attr->index]);
+}
+
+/* Shows the label associated with the specified ADC channel */
+static ssize_t powr1220_show_label(struct device *dev,
+	struct device_attribute *dev_attr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	return sprintf(buf, "%s\n", input_names[attr->index]);
+}
+
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON1);
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON2);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON3);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON4);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON5);
+static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON6);
+static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON7);
+static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON8);
+static SENSOR_DEVICE_ATTR(in8_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON9);
+static SENSOR_DEVICE_ATTR(in9_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON10);
+static SENSOR_DEVICE_ATTR(in10_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON11);
+static SENSOR_DEVICE_ATTR(in11_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VMON12);
+static SENSOR_DEVICE_ATTR(in12_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VCCA);
+static SENSOR_DEVICE_ATTR(in13_input, S_IRUGO, powr1220_show_voltage, NULL,
+	VCCINP);
+
+static SENSOR_DEVICE_ATTR(in0_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON1);
+static SENSOR_DEVICE_ATTR(in1_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON2);
+static SENSOR_DEVICE_ATTR(in2_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON3);
+static SENSOR_DEVICE_ATTR(in3_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON4);
+static SENSOR_DEVICE_ATTR(in4_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON5);
+static SENSOR_DEVICE_ATTR(in5_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON6);
+static SENSOR_DEVICE_ATTR(in6_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON7);
+static SENSOR_DEVICE_ATTR(in7_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON8);
+static SENSOR_DEVICE_ATTR(in8_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON9);
+static SENSOR_DEVICE_ATTR(in9_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON10);
+static SENSOR_DEVICE_ATTR(in10_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON11);
+static SENSOR_DEVICE_ATTR(in11_highest, S_IRUGO, powr1220_show_max, NULL,
+	VMON12);
+static SENSOR_DEVICE_ATTR(in12_highest, S_IRUGO, powr1220_show_max, NULL,
+	VCCA);
+static SENSOR_DEVICE_ATTR(in13_highest, S_IRUGO, powr1220_show_max, NULL,
+	VCCINP);
+
+static SENSOR_DEVICE_ATTR(in0_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON1);
+static SENSOR_DEVICE_ATTR(in1_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON2);
+static SENSOR_DEVICE_ATTR(in2_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON3);
+static SENSOR_DEVICE_ATTR(in3_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON4);
+static SENSOR_DEVICE_ATTR(in4_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON5);
+static SENSOR_DEVICE_ATTR(in5_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON6);
+static SENSOR_DEVICE_ATTR(in6_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON7);
+static SENSOR_DEVICE_ATTR(in7_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON8);
+static SENSOR_DEVICE_ATTR(in8_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON9);
+static SENSOR_DEVICE_ATTR(in9_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON10);
+static SENSOR_DEVICE_ATTR(in10_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON11);
+static SENSOR_DEVICE_ATTR(in11_label, S_IRUGO, powr1220_show_label, NULL,
+	VMON12);
+static SENSOR_DEVICE_ATTR(in12_label, S_IRUGO, powr1220_show_label, NULL,
+	VCCA);
+static SENSOR_DEVICE_ATTR(in13_label, S_IRUGO, powr1220_show_label, NULL,
+	VCCINP);
+
+static struct attribute *powr1220_attrs[] = {
+	&sensor_dev_attr_in0_input.dev_attr.attr,
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+	&sensor_dev_attr_in3_input.dev_attr.attr,
+	&sensor_dev_attr_in4_input.dev_attr.attr,
+	&sensor_dev_attr_in5_input.dev_attr.attr,
+	&sensor_dev_attr_in6_input.dev_attr.attr,
+	&sensor_dev_attr_in7_input.dev_attr.attr,
+	&sensor_dev_attr_in8_input.dev_attr.attr,
+	&sensor_dev_attr_in9_input.dev_attr.attr,
+	&sensor_dev_attr_in10_input.dev_attr.attr,
+	&sensor_dev_attr_in11_input.dev_attr.attr,
+	&sensor_dev_attr_in12_input.dev_attr.attr,
+	&sensor_dev_attr_in13_input.dev_attr.attr,
+
+	&sensor_dev_attr_in0_highest.dev_attr.attr,
+	&sensor_dev_attr_in1_highest.dev_attr.attr,
+	&sensor_dev_attr_in2_highest.dev_attr.attr,
+	&sensor_dev_attr_in3_highest.dev_attr.attr,
+	&sensor_dev_attr_in4_highest.dev_attr.attr,
+	&sensor_dev_attr_in5_highest.dev_attr.attr,
+	&sensor_dev_attr_in6_highest.dev_attr.attr,
+	&sensor_dev_attr_in7_highest.dev_attr.attr,
+	&sensor_dev_attr_in8_highest.dev_attr.attr,
+	&sensor_dev_attr_in9_highest.dev_attr.attr,
+	&sensor_dev_attr_in10_highest.dev_attr.attr,
+	&sensor_dev_attr_in11_highest.dev_attr.attr,
+	&sensor_dev_attr_in12_highest.dev_attr.attr,
+	&sensor_dev_attr_in13_highest.dev_attr.attr,
+
+	&sensor_dev_attr_in0_label.dev_attr.attr,
+	&sensor_dev_attr_in1_label.dev_attr.attr,
+	&sensor_dev_attr_in2_label.dev_attr.attr,
+	&sensor_dev_attr_in3_label.dev_attr.attr,
+	&sensor_dev_attr_in4_label.dev_attr.attr,
+	&sensor_dev_attr_in5_label.dev_attr.attr,
+	&sensor_dev_attr_in6_label.dev_attr.attr,
+	&sensor_dev_attr_in7_label.dev_attr.attr,
+	&sensor_dev_attr_in8_label.dev_attr.attr,
+	&sensor_dev_attr_in9_label.dev_attr.attr,
+	&sensor_dev_attr_in10_label.dev_attr.attr,
+	&sensor_dev_attr_in11_label.dev_attr.attr,
+	&sensor_dev_attr_in12_label.dev_attr.attr,
+	&sensor_dev_attr_in13_label.dev_attr.attr,
+
+	NULL
+};
+
+ATTRIBUTE_GROUPS(powr1220);
+
+static int powr1220_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct powr1220_data *data;
+	struct device *hwmon_dev;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	mutex_init(&data->update_lock);
+	data->client = client;
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
+			client->name, data, powr1220_groups);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id powr1220_ids[] = {
+	{ "powr1220", 0, },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, powr1220_ids);
+
+static struct i2c_driver powr1220_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "powr1220",
+	},
+	.probe		= powr1220_probe,
+	.id_table	= powr1220_ids,
+};
+
+module_i2c_driver(powr1220_driver);
+
+MODULE_AUTHOR("Scott Kanowitz");
+MODULE_DESCRIPTION("POWR1220 driver");
+MODULE_LICENSE("GPL");