drivers/hwmon/scpi-hwmon.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * System Control and Power Interface(SCPI) based hwmon sensor driver
   4  *
   5  * Copyright (C) 2015 ARM Ltd.
   6  * Punit Agrawal <punit.agrawal@arm.com>
   7  */
   8
   9 #include <linux/hwmon.h>
  10 #include <linux/module.h>
  11 #include <linux/of_device.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/scpi_protocol.h>
  14 #include <linux/slab.h>
  15 #include <linux/sysfs.h>
  16 #include <linux/thermal.h>
  17
  18 struct sensor_data {
  19         unsigned int scale;
  20         struct scpi_sensor_info info;
  21         struct device_attribute dev_attr_input;
  22         struct device_attribute dev_attr_label;
  23         char input[20];
  24         char label[20];
  25 };
  26
  27 struct scpi_thermal_zone {
  28         int sensor_id;
  29         struct scpi_sensors *scpi_sensors;
  30 };
  31
  32 struct scpi_sensors {
  33         struct scpi_ops *scpi_ops;
  34         struct sensor_data *data;
  35         struct list_head thermal_zones;
  36         struct attribute **attrs;
  37         struct attribute_group group;
  38         const struct attribute_group *groups[2];
  39 };
  40
  41 static const u32 gxbb_scpi_scale[] = {
  42         [TEMPERATURE]   = 1,            /* (celsius)            */
  43         [VOLTAGE]       = 1000,         /* (millivolts)         */
  44         [CURRENT]       = 1000,         /* (milliamperes)       */
  45         [POWER]         = 1000000,      /* (microwatts)         */
  46         [ENERGY]        = 1000000,      /* (microjoules)        */
  47 };
  48
  49 static const u32 scpi_scale[] = {
  50         [TEMPERATURE]   = 1000,         /* (millicelsius)       */
  51         [VOLTAGE]       = 1000,         /* (millivolts)         */
  52         [CURRENT]       = 1000,         /* (milliamperes)       */
  53         [POWER]         = 1000000,      /* (microwatts)         */
  54         [ENERGY]        = 1000000,      /* (microjoules)        */
  55 };
  56
  57 static void scpi_scale_reading(u64 *value, struct sensor_data *sensor)
  58 {
  59         if (scpi_scale[sensor->info.class] != sensor->scale) {
  60                 *value *= scpi_scale[sensor->info.class];
  61                 do_div(*value, sensor->scale);
  62         }
  63 }
  64
  65 static int scpi_read_temp(void *dev, int *temp)
  66 {
  67         struct scpi_thermal_zone *zone = dev;
  68         struct scpi_sensors *scpi_sensors = zone->scpi_sensors;
  69         struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
  70         struct sensor_data *sensor = &scpi_sensors->data[zone->sensor_id];
  71         u64 value;
  72         int ret;
  73
  74         ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
  75         if (ret)
  76                 return ret;
  77
  78         scpi_scale_reading(&value, sensor);
  79
  80         *temp = value;
  81         return 0;
  82 }
  83
  84 /* hwmon callback functions */
  85 static ssize_t
  86 scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
  87 {
  88         struct scpi_sensors *scpi_sensors = dev_get_drvdata(dev);
  89         struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
  90         struct sensor_data *sensor;
  91         u64 value;
  92         int ret;
  93
  94         sensor = container_of(attr, struct sensor_data, dev_attr_input);
  95
  96         ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
  97         if (ret)
  98                 return ret;
  99
 100         scpi_scale_reading(&value, sensor);
 101
 102         /*
 103          * Temperature sensor values are treated as signed values based on
 104          * observation even though that is not explicitly specified, and
 105          * because an unsigned u64 temperature does not really make practical
 106          * sense especially when the temperature is below zero degrees Celsius.
 107          */
 108         if (sensor->info.class == TEMPERATURE)
 109                 return sprintf(buf, "%lld\n", (s64)value);
 110
 111         return sprintf(buf, "%llu\n", value);
 112 }
 113
 114 static ssize_t
 115 scpi_show_label(struct device *dev, struct device_attribute *attr, char *buf)
 116 {
 117         struct sensor_data *sensor;
 118
 119         sensor = container_of(attr, struct sensor_data, dev_attr_label);
 120
 121         return sprintf(buf, "%s\n", sensor->info.name);
 122 }
 123
 124 static const struct thermal_zone_of_device_ops scpi_sensor_ops = {
 125         .get_temp = scpi_read_temp,
 126 };
 127
 128 static const struct of_device_id scpi_of_match[] = {
 129         {.compatible = "arm,scpi-sensors", .data = &scpi_scale},
 130         {.compatible = "amlogic,meson-gxbb-scpi-sensors", .data = &gxbb_scpi_scale},
 131         {},
 132 };
 133 MODULE_DEVICE_TABLE(of, scpi_of_match);
 134
 135 static int scpi_hwmon_probe(struct platform_device *pdev)
 136 {
 137         u16 nr_sensors, i;
 138         const u32 *scale;
 139         int num_temp = 0, num_volt = 0, num_current = 0, num_power = 0;
 140         int num_energy = 0;
 141         struct scpi_ops *scpi_ops;
 142         struct device *hwdev, *dev = &pdev->dev;
 143         struct scpi_sensors *scpi_sensors;
 144         const struct of_device_id *of_id;
 145         int idx, ret;
 146
 147         scpi_ops = get_scpi_ops();
 148         if (!scpi_ops)
 149                 return -EPROBE_DEFER;
 150
 151         ret = scpi_ops->sensor_get_capability(&nr_sensors);
 152         if (ret)
 153                 return ret;
 154
 155         if (!nr_sensors)
 156                 return -ENODEV;
 157
 158         scpi_sensors = devm_kzalloc(dev, sizeof(*scpi_sensors), GFP_KERNEL);
 159         if (!scpi_sensors)
 160                 return -ENOMEM;
 161
 162         scpi_sensors->data = devm_kcalloc(dev, nr_sensors,
 163                                    sizeof(*scpi_sensors->data), GFP_KERNEL);
 164         if (!scpi_sensors->data)
 165                 return -ENOMEM;
 166
 167         scpi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
 168                                    sizeof(*scpi_sensors->attrs), GFP_KERNEL);
 169         if (!scpi_sensors->attrs)
 170                 return -ENOMEM;
 171
 172         scpi_sensors->scpi_ops = scpi_ops;
 173
 174         of_id = of_match_device(scpi_of_match, &pdev->dev);
 175         if (!of_id) {
 176                 dev_err(&pdev->dev, "Unable to initialize scpi-hwmon data\n");
 177                 return -ENODEV;
 178         }
 179         scale = of_id->data;
 180
 181         for (i = 0, idx = 0; i < nr_sensors; i++) {
 182                 struct sensor_data *sensor = &scpi_sensors->data[idx];
 183
 184                 ret = scpi_ops->sensor_get_info(i, &sensor->info);
 185                 if (ret)
 186                         return ret;
 187
 188                 switch (sensor->info.class) {
 189                 case TEMPERATURE:
 190                         snprintf(sensor->input, sizeof(sensor->input),
 191                                  "temp%d_input", num_temp + 1);
 192                         snprintf(sensor->label, sizeof(sensor->input),
 193                                  "temp%d_label", num_temp + 1);
 194                         num_temp++;
 195                         break;
 196                 case VOLTAGE:
 197                         snprintf(sensor->input, sizeof(sensor->input),
 198                                  "in%d_input", num_volt);
 199                         snprintf(sensor->label, sizeof(sensor->input),
 200                                  "in%d_label", num_volt);
 201                         num_volt++;
 202                         break;
 203                 case CURRENT:
 204                         snprintf(sensor->input, sizeof(sensor->input),
 205                                  "curr%d_input", num_current + 1);
 206                         snprintf(sensor->label, sizeof(sensor->input),
 207                                  "curr%d_label", num_current + 1);
 208                         num_current++;
 209                         break;
 210                 case POWER:
 211                         snprintf(sensor->input, sizeof(sensor->input),
 212                                  "power%d_input", num_power + 1);
 213                         snprintf(sensor->label, sizeof(sensor->input),
 214                                  "power%d_label", num_power + 1);
 215                         num_power++;
 216                         break;
 217                 case ENERGY:
 218                         snprintf(sensor->input, sizeof(sensor->input),
 219                                  "energy%d_input", num_energy + 1);
 220                         snprintf(sensor->label, sizeof(sensor->input),
 221                                  "energy%d_label", num_energy + 1);
 222                         num_energy++;
 223                         break;
 224                 default:
 225                         continue;
 226                 }
 227
 228                 sensor->scale = scale[sensor->info.class];
 229
 230                 sensor->dev_attr_input.attr.mode = 0444;
 231                 sensor->dev_attr_input.show = scpi_show_sensor;
 232                 sensor->dev_attr_input.attr.name = sensor->input;
 233
 234                 sensor->dev_attr_label.attr.mode = 0444;
 235                 sensor->dev_attr_label.show = scpi_show_label;
 236                 sensor->dev_attr_label.attr.name = sensor->label;
 237
 238                 scpi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
 239                 scpi_sensors->attrs[(idx << 1) + 1] = &sensor->dev_attr_label.attr;
 240
 241                 sysfs_attr_init(scpi_sensors->attrs[idx << 1]);
 242                 sysfs_attr_init(scpi_sensors->attrs[(idx << 1) + 1]);
 243                 idx++;
 244         }
 245
 246         scpi_sensors->group.attrs = scpi_sensors->attrs;
 247         scpi_sensors->groups[0] = &scpi_sensors->group;
 248
 249         platform_set_drvdata(pdev, scpi_sensors);
 250
 251         hwdev = devm_hwmon_device_register_with_groups(dev,
 252                         "scpi_sensors", scpi_sensors, scpi_sensors->groups);
 253
 254         if (IS_ERR(hwdev))
 255                 return PTR_ERR(hwdev);
 256
 257         /*
 258          * Register the temperature sensors with the thermal framework
 259          * to allow their usage in setting up the thermal zones from
 260          * device tree.
 261          *
 262          * NOTE: Not all temperature sensors maybe used for thermal
 263          * control
 264          */
 265         INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
 266         for (i = 0; i < nr_sensors; i++) {
 267                 struct sensor_data *sensor = &scpi_sensors->data[i];
 268                 struct thermal_zone_device *z;
 269                 struct scpi_thermal_zone *zone;
 270
 271                 if (sensor->info.class != TEMPERATURE)
 272                         continue;
 273
 274                 zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
 275                 if (!zone)
 276                         return -ENOMEM;
 277
 278                 zone->sensor_id = i;
 279                 zone->scpi_sensors = scpi_sensors;
 280                 z = devm_thermal_zone_of_sensor_register(dev,
 281                                                          sensor->info.sensor_id,
 282                                                          zone,
 283                                                          &scpi_sensor_ops);
 284                 /*
 285                  * The call to thermal_zone_of_sensor_register returns
 286                  * an error for sensors that are not associated with
 287                  * any thermal zones or if the thermal subsystem is
 288                  * not configured.
 289                  */
 290                 if (IS_ERR(z))
 291                         devm_kfree(dev, zone);
 292         }
 293
 294         return 0;
 295 }
 296
 297 static struct platform_driver scpi_hwmon_platdrv = {
 298         .driver = {
 299                 .name   = "scpi-hwmon",
 300                 .of_match_table = scpi_of_match,
 301         },
 302         .probe          = scpi_hwmon_probe,
 303 };
 304 module_platform_driver(scpi_hwmon_platdrv);
 305
 306 MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
 307 MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
 308 MODULE_LICENSE("GPL v2");