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 
16 struct 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  */
28 static int rx51_battery_read_adc(struct iio_channel *channel)
29 {
30 	int val, err;
31 	err = iio_read_channel_average_raw(channel, &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  */
41 static int rx51_battery_read_voltage(struct rx51_device_info *di)
42 {
43 	int voltage = rx51_battery_read_adc(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  */
67 static 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
79 static 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  */
93 static 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(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 if (rx51_temp_table2[mid] > raw)
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  */
132 static int rx51_battery_read_capacity(struct rx51_device_info *di)
133 {
134 	int capacity = rx51_battery_read_adc(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  */
147 static 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 
182 static 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 
191 static int rx51_battery_probe(struct platform_device *pdev)
192 {
193 	struct power_supply_config psy_cfg = {};
194 	struct rx51_device_info *di;
195 	int ret;
196 
197 	di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
198 	if (!di)
199 		return -ENOMEM;
200 
201 	platform_set_drvdata(pdev, di);
202 
203 	di->dev = &pdev->dev;
204 	di->bat_desc.name = "rx51-battery";
205 	di->bat_desc.type = POWER_SUPPLY_TYPE_BATTERY;
206 	di->bat_desc.properties = rx51_battery_props;
207 	di->bat_desc.num_properties = ARRAY_SIZE(rx51_battery_props);
208 	di->bat_desc.get_property = rx51_battery_get_property;
209 
210 	psy_cfg.drv_data = di;
211 
212 	di->channel_temp = iio_channel_get(di->dev, "temp");
213 	if (IS_ERR(di->channel_temp)) {
214 		ret = PTR_ERR(di->channel_temp);
215 		goto error;
216 	}
217 
218 	di->channel_bsi  = iio_channel_get(di->dev, "bsi");
219 	if (IS_ERR(di->channel_bsi)) {
220 		ret = PTR_ERR(di->channel_bsi);
221 		goto error_channel_temp;
222 	}
223 
224 	di->channel_vbat = iio_channel_get(di->dev, "vbat");
225 	if (IS_ERR(di->channel_vbat)) {
226 		ret = PTR_ERR(di->channel_vbat);
227 		goto error_channel_bsi;
228 	}
229 
230 	di->bat = power_supply_register(di->dev, &di->bat_desc, &psy_cfg);
231 	if (IS_ERR(di->bat)) {
232 		ret = PTR_ERR(di->bat);
233 		goto error_channel_vbat;
234 	}
235 
236 	return 0;
237 
238 error_channel_vbat:
239 	iio_channel_release(di->channel_vbat);
240 error_channel_bsi:
241 	iio_channel_release(di->channel_bsi);
242 error_channel_temp:
243 	iio_channel_release(di->channel_temp);
244 error:
245 
246 	return ret;
247 }
248 
249 static int rx51_battery_remove(struct platform_device *pdev)
250 {
251 	struct rx51_device_info *di = platform_get_drvdata(pdev);
252 
253 	power_supply_unregister(di->bat);
254 
255 	iio_channel_release(di->channel_vbat);
256 	iio_channel_release(di->channel_bsi);
257 	iio_channel_release(di->channel_temp);
258 
259 	return 0;
260 }
261 
262 #ifdef CONFIG_OF
263 static const struct of_device_id n900_battery_of_match[] = {
264 	{.compatible = "nokia,n900-battery", },
265 	{ },
266 };
267 MODULE_DEVICE_TABLE(of, n900_battery_of_match);
268 #endif
269 
270 static struct platform_driver rx51_battery_driver = {
271 	.probe = rx51_battery_probe,
272 	.remove = rx51_battery_remove,
273 	.driver = {
274 		.name = "rx51-battery",
275 		.of_match_table = of_match_ptr(n900_battery_of_match),
276 	},
277 };
278 module_platform_driver(rx51_battery_driver);
279 
280 MODULE_ALIAS("platform:rx51-battery");
281 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
282 MODULE_DESCRIPTION("Nokia RX-51 battery driver");
283 MODULE_LICENSE("GPL");
284