1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Nokia RX-51 battery driver
4 *
5 * Copyright (C) 2012 Pali Rohár <pali@kernel.org>
6 */
7
8#include <linux/module.h>
9#include <linux/param.h>
10#include <linux/platform_device.h>
11#include <linux/power_supply.h>
12#include <linux/slab.h>
13#include <linux/iio/consumer.h>
14#include <linux/of.h>
15
16struct rx51_device_info {
17 struct device *dev;
18 struct power_supply *bat;
19 struct power_supply_desc bat_desc;
20 struct iio_channel *channel_temp;
21 struct iio_channel *channel_bsi;
22 struct iio_channel *channel_vbat;
23};
24
25/*
26 * Read ADCIN channel value, code copied from maemo kernel
27 */
28static int rx51_battery_read_adc(struct iio_channel *channel)
29{
30 int val, err;
31 err = iio_read_channel_average_raw(chan: channel, val: &val);
32 if (err < 0)
33 return err;
34 return val;
35}
36
37/*
38 * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
39 * This conversion formula was extracted from maemo program bsi-read
40 */
41static int rx51_battery_read_voltage(struct rx51_device_info *di)
42{
43 int voltage = rx51_battery_read_adc(channel: di->channel_vbat);
44
45 if (voltage < 0) {
46 dev_err(di->dev, "Could not read ADC: %d\n", voltage);
47 return voltage;
48 }
49
50 return 1000 * (10000 * voltage / 1705);
51}
52
53/*
54 * Temperature look-up tables
55 * TEMP = (1/(t1 + 1/298) - 273.15)
56 * Where t1 = (1/B) * ln((RAW_ADC_U * 2.5)/(R * I * 255))
57 * Formula is based on experimental data, RX-51 CAL data, maemo program bme
58 * and formula from da9052 driver with values R = 100, B = 3380, I = 0.00671
59 */
60
61/*
62 * Table1 (temperature for first 25 RAW values)
63 * Usage: TEMP = rx51_temp_table1[RAW]
64 * RAW is between 1 and 24
65 * TEMP is between 201 C and 55 C
66 */
67static u8 rx51_temp_table1[] = {
68 255, 201, 159, 138, 124, 114, 106, 99, 94, 89, 85, 82, 78, 75,
69 73, 70, 68, 66, 64, 62, 61, 59, 57, 56, 55
70};
71
72/*
73 * Table2 (lowest RAW value for temperature)
74 * Usage: RAW = rx51_temp_table2[TEMP-rx51_temp_table2_first]
75 * TEMP is between 53 C and -32 C
76 * RAW is between 25 and 993
77 */
78#define rx51_temp_table2_first 53
79static u16 rx51_temp_table2[] = {
80 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39,
81 40, 41, 43, 44, 46, 48, 49, 51, 53, 55, 57, 59, 61, 64,
82 66, 69, 71, 74, 77, 80, 83, 86, 90, 94, 97, 101, 106, 110,
83 115, 119, 125, 130, 136, 141, 148, 154, 161, 168, 176, 184, 202, 211,
84 221, 231, 242, 254, 266, 279, 293, 308, 323, 340, 357, 375, 395, 415,
85 437, 460, 485, 511, 539, 568, 600, 633, 669, 706, 747, 790, 836, 885,
86 937, 993, 1024
87};
88
89/*
90 * Read ADCIN channel 0 (battery temp) and convert value to tenths of Celsius
91 * Use Temperature look-up tables for conversation
92 */
93static int rx51_battery_read_temperature(struct rx51_device_info *di)
94{
95 int min = 0;
96 int max = ARRAY_SIZE(rx51_temp_table2) - 1;
97 int raw = rx51_battery_read_adc(channel: di->channel_temp);
98
99 if (raw < 0)
100 dev_err(di->dev, "Could not read ADC: %d\n", raw);
101
102 /* Zero and negative values are undefined */
103 if (raw <= 0)
104 return INT_MAX;
105
106 /* ADC channels are 10 bit, higher value are undefined */
107 if (raw >= (1 << 10))
108 return INT_MIN;
109
110 /* First check for temperature in first direct table */
111 if (raw < ARRAY_SIZE(rx51_temp_table1))
112 return rx51_temp_table1[raw] * 10;
113
114 /* Binary search RAW value in second inverse table */
115 while (max - min > 1) {
116 int mid = (max + min) / 2;
117 if (rx51_temp_table2[mid] <= raw)
118 min = mid;
119 else
120 max = mid;
121 if (rx51_temp_table2[mid] == raw)
122 break;
123 }
124
125 return (rx51_temp_table2_first - min) * 10;
126}
127
128/*
129 * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
130 * This conversion formula was extracted from maemo program bsi-read
131 */
132static int rx51_battery_read_capacity(struct rx51_device_info *di)
133{
134 int capacity = rx51_battery_read_adc(channel: di->channel_bsi);
135
136 if (capacity < 0) {
137 dev_err(di->dev, "Could not read ADC: %d\n", capacity);
138 return capacity;
139 }
140
141 return 1280 * (1200 * capacity)/(1024 - capacity);
142}
143
144/*
145 * Return power_supply property
146 */
147static int rx51_battery_get_property(struct power_supply *psy,
148 enum power_supply_property psp,
149 union power_supply_propval *val)
150{
151 struct rx51_device_info *di = power_supply_get_drvdata(psy);
152
153 switch (psp) {
154 case POWER_SUPPLY_PROP_TECHNOLOGY:
155 val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
156 break;
157 case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
158 val->intval = 4200000;
159 break;
160 case POWER_SUPPLY_PROP_PRESENT:
161 val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
162 break;
163 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
164 val->intval = rx51_battery_read_voltage(di);
165 break;
166 case POWER_SUPPLY_PROP_TEMP:
167 val->intval = rx51_battery_read_temperature(di);
168 break;
169 case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
170 val->intval = rx51_battery_read_capacity(di);
171 break;
172 default:
173 return -EINVAL;
174 }
175
176 if (val->intval == INT_MAX || val->intval == INT_MIN)
177 return -EINVAL;
178
179 return 0;
180}
181
182static enum power_supply_property rx51_battery_props[] = {
183 POWER_SUPPLY_PROP_TECHNOLOGY,
184 POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
185 POWER_SUPPLY_PROP_PRESENT,
186 POWER_SUPPLY_PROP_VOLTAGE_NOW,
187 POWER_SUPPLY_PROP_TEMP,
188 POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
189};
190
191static int rx51_battery_probe(struct platform_device *pdev)
192{
193 struct power_supply_config psy_cfg = {};
194 struct rx51_device_info *di;
195
196 di = devm_kzalloc(dev: &pdev->dev, size: sizeof(*di), GFP_KERNEL);
197 if (!di)
198 return -ENOMEM;
199
200 di->dev = &pdev->dev;
201 di->bat_desc.name = "rx51-battery";
202 di->bat_desc.type = POWER_SUPPLY_TYPE_BATTERY;
203 di->bat_desc.properties = rx51_battery_props;
204 di->bat_desc.num_properties = ARRAY_SIZE(rx51_battery_props);
205 di->bat_desc.get_property = rx51_battery_get_property;
206
207 psy_cfg.drv_data = di;
208
209 di->channel_temp = devm_iio_channel_get(dev: di->dev, consumer_channel: "temp");
210 if (IS_ERR(ptr: di->channel_temp))
211 return PTR_ERR(ptr: di->channel_temp);
212
213 di->channel_bsi = devm_iio_channel_get(dev: di->dev, consumer_channel: "bsi");
214 if (IS_ERR(ptr: di->channel_bsi))
215 return PTR_ERR(ptr: di->channel_bsi);
216
217 di->channel_vbat = devm_iio_channel_get(dev: di->dev, consumer_channel: "vbat");
218 if (IS_ERR(ptr: di->channel_vbat))
219 return PTR_ERR(ptr: di->channel_vbat);
220
221 di->bat = devm_power_supply_register(parent: di->dev, desc: &di->bat_desc, cfg: &psy_cfg);
222 if (IS_ERR(ptr: di->bat))
223 return PTR_ERR(ptr: di->bat);
224
225 return 0;
226}
227
228#ifdef CONFIG_OF
229static const struct of_device_id n900_battery_of_match[] = {
230 {.compatible = "nokia,n900-battery", },
231 { },
232};
233MODULE_DEVICE_TABLE(of, n900_battery_of_match);
234#endif
235
236static struct platform_driver rx51_battery_driver = {
237 .probe = rx51_battery_probe,
238 .driver = {
239 .name = "rx51-battery",
240 .of_match_table = of_match_ptr(n900_battery_of_match),
241 },
242};
243module_platform_driver(rx51_battery_driver);
244
245MODULE_ALIAS("platform:rx51-battery");
246MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
247MODULE_DESCRIPTION("Nokia RX-51 battery driver");
248MODULE_LICENSE("GPL");
249

source code of linux/drivers/power/supply/rx51_battery.c