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
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(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 */
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_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	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
295static 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};
302module_platform_driver(scpi_hwmon_platdrv);
303
304MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
305MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
306MODULE_LICENSE("GPL v2");
307