xref: /openbmc/linux/drivers/hwmon/scpi-hwmon.c (revision 39f03438)
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.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 
scpi_scale_reading(u64 * value,struct sensor_data * sensor)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 
scpi_read_temp(struct thermal_zone_device * tz,int * temp)65 static int scpi_read_temp(struct thermal_zone_device *tz, int *temp)
66 {
67 	struct scpi_thermal_zone *zone = thermal_zone_device_priv(tz);
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
scpi_show_sensor(struct device * dev,struct device_attribute * attr,char * buf)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
scpi_show_label(struct device * dev,struct device_attribute * attr,char * buf)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_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 
scpi_hwmon_probe(struct platform_device * pdev)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 	int idx, ret;
145 
146 	scpi_ops = get_scpi_ops();
147 	if (!scpi_ops)
148 		return -EPROBE_DEFER;
149 
150 	ret = scpi_ops->sensor_get_capability(&nr_sensors);
151 	if (ret)
152 		return ret;
153 
154 	if (!nr_sensors)
155 		return -ENODEV;
156 
157 	scpi_sensors = devm_kzalloc(dev, sizeof(*scpi_sensors), GFP_KERNEL);
158 	if (!scpi_sensors)
159 		return -ENOMEM;
160 
161 	scpi_sensors->data = devm_kcalloc(dev, nr_sensors,
162 				   sizeof(*scpi_sensors->data), GFP_KERNEL);
163 	if (!scpi_sensors->data)
164 		return -ENOMEM;
165 
166 	scpi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
167 				   sizeof(*scpi_sensors->attrs), GFP_KERNEL);
168 	if (!scpi_sensors->attrs)
169 		return -ENOMEM;
170 
171 	scpi_sensors->scpi_ops = scpi_ops;
172 
173 	scale = of_device_get_match_data(&pdev->dev);
174 	if (!scale) {
175 		dev_err(&pdev->dev, "Unable to initialize scpi-hwmon data\n");
176 		return -ENODEV;
177 	}
178 
179 	for (i = 0, idx = 0; i < nr_sensors; i++) {
180 		struct sensor_data *sensor = &scpi_sensors->data[idx];
181 
182 		ret = scpi_ops->sensor_get_info(i, &sensor->info);
183 		if (ret)
184 			return ret;
185 
186 		switch (sensor->info.class) {
187 		case TEMPERATURE:
188 			snprintf(sensor->input, sizeof(sensor->input),
189 				 "temp%d_input", num_temp + 1);
190 			snprintf(sensor->label, sizeof(sensor->input),
191 				 "temp%d_label", num_temp + 1);
192 			num_temp++;
193 			break;
194 		case VOLTAGE:
195 			snprintf(sensor->input, sizeof(sensor->input),
196 				 "in%d_input", num_volt);
197 			snprintf(sensor->label, sizeof(sensor->input),
198 				 "in%d_label", num_volt);
199 			num_volt++;
200 			break;
201 		case CURRENT:
202 			snprintf(sensor->input, sizeof(sensor->input),
203 				 "curr%d_input", num_current + 1);
204 			snprintf(sensor->label, sizeof(sensor->input),
205 				 "curr%d_label", num_current + 1);
206 			num_current++;
207 			break;
208 		case POWER:
209 			snprintf(sensor->input, sizeof(sensor->input),
210 				 "power%d_input", num_power + 1);
211 			snprintf(sensor->label, sizeof(sensor->input),
212 				 "power%d_label", num_power + 1);
213 			num_power++;
214 			break;
215 		case ENERGY:
216 			snprintf(sensor->input, sizeof(sensor->input),
217 				 "energy%d_input", num_energy + 1);
218 			snprintf(sensor->label, sizeof(sensor->input),
219 				 "energy%d_label", num_energy + 1);
220 			num_energy++;
221 			break;
222 		default:
223 			continue;
224 		}
225 
226 		sensor->scale = scale[sensor->info.class];
227 
228 		sensor->dev_attr_input.attr.mode = 0444;
229 		sensor->dev_attr_input.show = scpi_show_sensor;
230 		sensor->dev_attr_input.attr.name = sensor->input;
231 
232 		sensor->dev_attr_label.attr.mode = 0444;
233 		sensor->dev_attr_label.show = scpi_show_label;
234 		sensor->dev_attr_label.attr.name = sensor->label;
235 
236 		scpi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
237 		scpi_sensors->attrs[(idx << 1) + 1] = &sensor->dev_attr_label.attr;
238 
239 		sysfs_attr_init(scpi_sensors->attrs[idx << 1]);
240 		sysfs_attr_init(scpi_sensors->attrs[(idx << 1) + 1]);
241 		idx++;
242 	}
243 
244 	scpi_sensors->group.attrs = scpi_sensors->attrs;
245 	scpi_sensors->groups[0] = &scpi_sensors->group;
246 
247 	platform_set_drvdata(pdev, scpi_sensors);
248 
249 	hwdev = devm_hwmon_device_register_with_groups(dev,
250 			"scpi_sensors", scpi_sensors, scpi_sensors->groups);
251 
252 	if (IS_ERR(hwdev))
253 		return PTR_ERR(hwdev);
254 
255 	/*
256 	 * Register the temperature sensors with the thermal framework
257 	 * to allow their usage in setting up the thermal zones from
258 	 * device tree.
259 	 *
260 	 * NOTE: Not all temperature sensors maybe used for thermal
261 	 * control
262 	 */
263 	INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
264 	for (i = 0; i < nr_sensors; i++) {
265 		struct sensor_data *sensor = &scpi_sensors->data[i];
266 		struct thermal_zone_device *z;
267 		struct scpi_thermal_zone *zone;
268 
269 		if (sensor->info.class != TEMPERATURE)
270 			continue;
271 
272 		zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
273 		if (!zone)
274 			return -ENOMEM;
275 
276 		zone->sensor_id = i;
277 		zone->scpi_sensors = scpi_sensors;
278 		z = devm_thermal_of_zone_register(dev,
279 						  sensor->info.sensor_id,
280 						  zone,
281 						  &scpi_sensor_ops);
282 		/*
283 		 * The call to thermal_zone_of_sensor_register returns
284 		 * an error for sensors that are not associated with
285 		 * any thermal zones or if the thermal subsystem is
286 		 * not configured.
287 		 */
288 		if (IS_ERR(z))
289 			devm_kfree(dev, zone);
290 	}
291 
292 	return 0;
293 }
294 
295 static struct platform_driver scpi_hwmon_platdrv = {
296 	.driver = {
297 		.name	= "scpi-hwmon",
298 		.of_match_table = scpi_of_match,
299 	},
300 	.probe		= scpi_hwmon_probe,
301 };
302 module_platform_driver(scpi_hwmon_platdrv);
303 
304 MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
305 MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
306 MODULE_LICENSE("GPL v2");
307