1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
|
/*
* Battery driver for LEGO MINDSTORMS EV3
*
* Copyright (C) 2017 David Lechner <david@lechnology.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/iio/consumer.h>
#include <linux/iio/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
struct lego_ev3_battery {
struct iio_channel *iio_v;
struct iio_channel *iio_i;
struct gpio_desc *rechargeable_gpio;
struct power_supply *psy;
int technology;
int v_max;
int v_min;
};
static int lego_ev3_battery_get_property(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val)
{
struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
int ret, val2;
switch (psp) {
case POWER_SUPPLY_PROP_TECHNOLOGY:
val->intval = batt->technology;
break;
case POWER_SUPPLY_PROP_VOLTAGE_NOW:
/* battery voltage is iio channel * 2 + Vce of transistor */
ret = iio_read_channel_processed(batt->iio_v, &val->intval);
if (ret)
return ret;
val->intval *= 2000;
val->intval += 50000;
/* plus adjust for shunt resistor drop */
ret = iio_read_channel_processed(batt->iio_i, &val2);
if (ret)
return ret;
val2 *= 1000;
val2 /= 15;
val->intval += val2;
break;
case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
val->intval = batt->v_max;
break;
case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
val->intval = batt->v_min;
break;
case POWER_SUPPLY_PROP_CURRENT_NOW:
/* battery current is iio channel / 15 / 0.05 ohms */
ret = iio_read_channel_processed(batt->iio_i, &val->intval);
if (ret)
return ret;
val->intval *= 20000;
val->intval /= 15;
break;
case POWER_SUPPLY_PROP_SCOPE:
val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
break;
default:
return -EINVAL;
}
return 0;
}
static int lego_ev3_battery_set_property(struct power_supply *psy,
enum power_supply_property psp,
const union power_supply_propval *val)
{
struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
switch (psp) {
case POWER_SUPPLY_PROP_TECHNOLOGY:
/*
* Only allow changing technology from Unknown to NiMH. Li-ion
* batteries are automatically detected and should not be
* overridden. Rechargeable AA batteries, on the other hand,
* cannot be automatically detected, and so must be manually
* specified. This should only be set once during system init,
* so there is no mechanism to go back to Unknown.
*/
if (batt->technology != POWER_SUPPLY_TECHNOLOGY_UNKNOWN)
return -EINVAL;
switch (val->intval) {
case POWER_SUPPLY_TECHNOLOGY_NiMH:
batt->technology = POWER_SUPPLY_TECHNOLOGY_NiMH;
batt->v_max = 7800000;
batt->v_min = 5400000;
break;
default:
return -EINVAL;
}
break;
default:
return -EINVAL;
}
return 0;
}
static int lego_ev3_battery_property_is_writeable(struct power_supply *psy,
enum power_supply_property psp)
{
struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
return psp == POWER_SUPPLY_PROP_TECHNOLOGY &&
batt->technology == POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
}
static enum power_supply_property lego_ev3_battery_props[] = {
POWER_SUPPLY_PROP_TECHNOLOGY,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_SCOPE,
};
static const struct power_supply_desc lego_ev3_battery_desc = {
.name = "lego-ev3-battery",
.type = POWER_SUPPLY_TYPE_BATTERY,
.properties = lego_ev3_battery_props,
.num_properties = ARRAY_SIZE(lego_ev3_battery_props),
.get_property = lego_ev3_battery_get_property,
.set_property = lego_ev3_battery_set_property,
.property_is_writeable = lego_ev3_battery_property_is_writeable,
};
static int lego_ev3_battery_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct lego_ev3_battery *batt;
struct power_supply_config psy_cfg = {};
int err;
batt = devm_kzalloc(dev, sizeof(*batt), GFP_KERNEL);
if (!batt)
return -ENOMEM;
platform_set_drvdata(pdev, batt);
batt->iio_v = devm_iio_channel_get(dev, "voltage");
err = PTR_ERR_OR_ZERO(batt->iio_v);
if (err)
return dev_err_probe(dev, err,
"Failed to get voltage iio channel\n");
batt->iio_i = devm_iio_channel_get(dev, "current");
err = PTR_ERR_OR_ZERO(batt->iio_i);
if (err)
return dev_err_probe(dev, err,
"Failed to get current iio channel\n");
batt->rechargeable_gpio = devm_gpiod_get(dev, "rechargeable", GPIOD_IN);
err = PTR_ERR_OR_ZERO(batt->rechargeable_gpio);
if (err)
return dev_err_probe(dev, err,
"Failed to get rechargeable gpio\n");
/*
* The rechargeable battery indication switch cannot be changed without
* removing the battery, so we only need to read it once.
*/
if (gpiod_get_value(batt->rechargeable_gpio)) {
/* 2-cell Li-ion, 7.4V nominal */
batt->technology = POWER_SUPPLY_TECHNOLOGY_LION;
batt->v_max = 84000000;
batt->v_min = 60000000;
} else {
/* 6x AA Alkaline, 9V nominal */
batt->technology = POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
batt->v_max = 90000000;
batt->v_min = 48000000;
}
psy_cfg.of_node = pdev->dev.of_node;
psy_cfg.drv_data = batt;
batt->psy = devm_power_supply_register(dev, &lego_ev3_battery_desc,
&psy_cfg);
err = PTR_ERR_OR_ZERO(batt->psy);
if (err) {
dev_err(dev, "failed to register power supply\n");
return err;
}
return 0;
}
static const struct of_device_id of_lego_ev3_battery_match[] = {
{ .compatible = "lego,ev3-battery", },
{ }
};
MODULE_DEVICE_TABLE(of, of_lego_ev3_battery_match);
static struct platform_driver lego_ev3_battery_driver = {
.driver = {
.name = "lego-ev3-battery",
.of_match_table = of_lego_ev3_battery_match,
},
.probe = lego_ev3_battery_probe,
};
module_platform_driver(lego_ev3_battery_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Lechner <david@lechnology.com>");
MODULE_DESCRIPTION("LEGO MINDSTORMS EV3 Battery Driver");
|
