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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
18struct 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
27struct scpi_thermal_zone {
28 int sensor_id;
29 struct scpi_sensors *scpi_sensors;
30};
31
32struct 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
41static 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
49static 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
57static 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
65static 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 */
85static ssize_t
86scpi_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
114static ssize_t
115scpi_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
124static const struct thermal_zone_of_device_ops scpi_sensor_ops = {
125 .get_temp = scpi_read_temp,
126};
127
128static 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};
133MODULE_DEVICE_TABLE(of, scpi_of_match);
134
135static 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
297static 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};
304module_platform_driver(scpi_hwmon_platdrv);
305
306MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
307MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
308MODULE_LICENSE("GPL v2");