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![Carlo Caione](/assets/img/avatar_default.png)
The implementation details for SCPI seems to suggest that the sensor readings must be reported by SCP using a well defined scale (millidegree Celsius for temperature, millivolts for voltage, milliamperes for current, microwatts for power and microjoules for energy). This is also important for the interaction with other subsystems: for example both the thermal sub-system and the hwmon sysfs interface expect the temperature expressed in millidegree Celsius. Unfortunately since this behaviour is dependent on the firmware implementation there are cases where the sensor readings are reported using a different scale. For example in the Amlogic SoCs the temperature is reported in degree and not millidegree Celsius. To take into account this discrepancy and fixup the values reported by SCP a new compatible 'amlogic,meson-gxbb-scpi-sensors' is introduced and used in this patch by the scpi-hwmon driver to convert the sensor readings to the expected scale. Signed-off-by: Carlo Caione <carlo@endlessm.com> Acked-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
309 lines
8.1 KiB
C
309 lines
8.1 KiB
C
/*
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* System Control and Power Interface(SCPI) based hwmon sensor driver
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*
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* Copyright (C) 2015 ARM Ltd.
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* Punit Agrawal <punit.agrawal@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/hwmon.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/scpi_protocol.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/thermal.h>
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struct sensor_data {
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unsigned int scale;
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struct scpi_sensor_info info;
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struct device_attribute dev_attr_input;
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struct device_attribute dev_attr_label;
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char input[20];
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char label[20];
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};
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struct scpi_thermal_zone {
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int sensor_id;
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struct scpi_sensors *scpi_sensors;
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};
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struct scpi_sensors {
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struct scpi_ops *scpi_ops;
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struct sensor_data *data;
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struct list_head thermal_zones;
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struct attribute **attrs;
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struct attribute_group group;
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const struct attribute_group *groups[2];
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};
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static const u32 gxbb_scpi_scale[] = {
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[TEMPERATURE] = 1, /* (celsius) */
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[VOLTAGE] = 1000, /* (millivolts) */
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[CURRENT] = 1000, /* (milliamperes) */
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[POWER] = 1000000, /* (microwatts) */
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[ENERGY] = 1000000, /* (microjoules) */
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};
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static const u32 scpi_scale[] = {
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[TEMPERATURE] = 1000, /* (millicelsius) */
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[VOLTAGE] = 1000, /* (millivolts) */
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[CURRENT] = 1000, /* (milliamperes) */
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[POWER] = 1000000, /* (microwatts) */
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[ENERGY] = 1000000, /* (microjoules) */
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};
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static void scpi_scale_reading(u64 *value, struct sensor_data *sensor)
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{
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if (scpi_scale[sensor->info.class] != sensor->scale) {
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*value *= scpi_scale[sensor->info.class];
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do_div(*value, sensor->scale);
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}
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}
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static int scpi_read_temp(void *dev, int *temp)
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{
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struct scpi_thermal_zone *zone = dev;
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struct scpi_sensors *scpi_sensors = zone->scpi_sensors;
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struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
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struct sensor_data *sensor = &scpi_sensors->data[zone->sensor_id];
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u64 value;
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int ret;
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ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
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if (ret)
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return ret;
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scpi_scale_reading(&value, sensor);
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*temp = value;
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return 0;
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}
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/* hwmon callback functions */
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static ssize_t
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scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct scpi_sensors *scpi_sensors = dev_get_drvdata(dev);
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struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
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struct sensor_data *sensor;
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u64 value;
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int ret;
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sensor = container_of(attr, struct sensor_data, dev_attr_input);
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ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
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if (ret)
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return ret;
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scpi_scale_reading(&value, sensor);
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return sprintf(buf, "%llu\n", value);
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}
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static ssize_t
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scpi_show_label(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct sensor_data *sensor;
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sensor = container_of(attr, struct sensor_data, dev_attr_label);
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return sprintf(buf, "%s\n", sensor->info.name);
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}
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static struct thermal_zone_of_device_ops scpi_sensor_ops = {
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.get_temp = scpi_read_temp,
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};
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static const struct of_device_id scpi_of_match[] = {
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{.compatible = "arm,scpi-sensors", .data = &scpi_scale},
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{.compatible = "amlogic,meson-gxbb-scpi-sensors", .data = &gxbb_scpi_scale},
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{},
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};
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MODULE_DEVICE_TABLE(of, scpi_of_match);
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static int scpi_hwmon_probe(struct platform_device *pdev)
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{
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u16 nr_sensors, i;
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const u32 *scale;
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int num_temp = 0, num_volt = 0, num_current = 0, num_power = 0;
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int num_energy = 0;
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struct scpi_ops *scpi_ops;
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struct device *hwdev, *dev = &pdev->dev;
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struct scpi_sensors *scpi_sensors;
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const struct of_device_id *of_id;
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int idx, ret;
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scpi_ops = get_scpi_ops();
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if (!scpi_ops)
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return -EPROBE_DEFER;
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ret = scpi_ops->sensor_get_capability(&nr_sensors);
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if (ret)
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return ret;
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if (!nr_sensors)
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return -ENODEV;
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scpi_sensors = devm_kzalloc(dev, sizeof(*scpi_sensors), GFP_KERNEL);
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if (!scpi_sensors)
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return -ENOMEM;
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scpi_sensors->data = devm_kcalloc(dev, nr_sensors,
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sizeof(*scpi_sensors->data), GFP_KERNEL);
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if (!scpi_sensors->data)
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return -ENOMEM;
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scpi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
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sizeof(*scpi_sensors->attrs), GFP_KERNEL);
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if (!scpi_sensors->attrs)
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return -ENOMEM;
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scpi_sensors->scpi_ops = scpi_ops;
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of_id = of_match_device(scpi_of_match, &pdev->dev);
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if (!of_id) {
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dev_err(&pdev->dev, "Unable to initialize scpi-hwmon data\n");
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return -ENODEV;
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}
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scale = of_id->data;
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for (i = 0, idx = 0; i < nr_sensors; i++) {
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struct sensor_data *sensor = &scpi_sensors->data[idx];
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ret = scpi_ops->sensor_get_info(i, &sensor->info);
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if (ret)
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return ret;
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switch (sensor->info.class) {
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case TEMPERATURE:
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snprintf(sensor->input, sizeof(sensor->input),
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"temp%d_input", num_temp + 1);
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snprintf(sensor->label, sizeof(sensor->input),
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"temp%d_label", num_temp + 1);
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num_temp++;
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break;
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case VOLTAGE:
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snprintf(sensor->input, sizeof(sensor->input),
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"in%d_input", num_volt);
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snprintf(sensor->label, sizeof(sensor->input),
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"in%d_label", num_volt);
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num_volt++;
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break;
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case CURRENT:
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snprintf(sensor->input, sizeof(sensor->input),
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"curr%d_input", num_current + 1);
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snprintf(sensor->label, sizeof(sensor->input),
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"curr%d_label", num_current + 1);
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num_current++;
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break;
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case POWER:
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snprintf(sensor->input, sizeof(sensor->input),
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"power%d_input", num_power + 1);
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snprintf(sensor->label, sizeof(sensor->input),
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"power%d_label", num_power + 1);
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num_power++;
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break;
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case ENERGY:
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snprintf(sensor->input, sizeof(sensor->input),
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"energy%d_input", num_energy + 1);
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snprintf(sensor->label, sizeof(sensor->input),
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"energy%d_label", num_energy + 1);
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num_energy++;
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break;
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default:
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continue;
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}
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sensor->scale = scale[sensor->info.class];
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sensor->dev_attr_input.attr.mode = S_IRUGO;
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sensor->dev_attr_input.show = scpi_show_sensor;
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sensor->dev_attr_input.attr.name = sensor->input;
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sensor->dev_attr_label.attr.mode = S_IRUGO;
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sensor->dev_attr_label.show = scpi_show_label;
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sensor->dev_attr_label.attr.name = sensor->label;
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scpi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
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scpi_sensors->attrs[(idx << 1) + 1] = &sensor->dev_attr_label.attr;
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sysfs_attr_init(scpi_sensors->attrs[idx << 1]);
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sysfs_attr_init(scpi_sensors->attrs[(idx << 1) + 1]);
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idx++;
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}
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scpi_sensors->group.attrs = scpi_sensors->attrs;
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scpi_sensors->groups[0] = &scpi_sensors->group;
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platform_set_drvdata(pdev, scpi_sensors);
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hwdev = devm_hwmon_device_register_with_groups(dev,
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"scpi_sensors", scpi_sensors, scpi_sensors->groups);
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if (IS_ERR(hwdev))
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return PTR_ERR(hwdev);
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/*
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* Register the temperature sensors with the thermal framework
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* to allow their usage in setting up the thermal zones from
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* device tree.
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*
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* NOTE: Not all temperature sensors maybe used for thermal
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* control
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*/
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INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
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for (i = 0; i < nr_sensors; i++) {
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struct sensor_data *sensor = &scpi_sensors->data[i];
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struct thermal_zone_device *z;
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struct scpi_thermal_zone *zone;
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if (sensor->info.class != TEMPERATURE)
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continue;
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zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
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if (!zone)
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return -ENOMEM;
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zone->sensor_id = i;
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zone->scpi_sensors = scpi_sensors;
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z = devm_thermal_zone_of_sensor_register(dev,
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sensor->info.sensor_id,
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zone,
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&scpi_sensor_ops);
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/*
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* The call to thermal_zone_of_sensor_register returns
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* an error for sensors that are not associated with
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* any thermal zones or if the thermal subsystem is
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* not configured.
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*/
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if (IS_ERR(z)) {
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devm_kfree(dev, zone);
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continue;
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}
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}
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return 0;
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}
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static struct platform_driver scpi_hwmon_platdrv = {
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.driver = {
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.name = "scpi-hwmon",
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.of_match_table = scpi_of_match,
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},
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.probe = scpi_hwmon_probe,
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};
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module_platform_driver(scpi_hwmon_platdrv);
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MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
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MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
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MODULE_LICENSE("GPL v2");
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