rx51_battery.c

  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(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 */
 41static 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 */
 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(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(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(&pdev->dev, 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(di->dev, "temp");
210	if (IS_ERR(di->channel_temp))
211		return PTR_ERR(di->channel_temp);
212
213	di->channel_bsi  = devm_iio_channel_get(di->dev, "bsi");
214	if (IS_ERR(di->channel_bsi))
215		return PTR_ERR(di->channel_bsi);
216
217	di->channel_vbat = devm_iio_channel_get(di->dev, "vbat");
218	if (IS_ERR(di->channel_vbat))
219		return PTR_ERR(di->channel_vbat);
220
221	di->bat = devm_power_supply_register(di->dev, &di->bat_desc, &psy_cfg);
222	if (IS_ERR(di->bat))
223		return PTR_ERR(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");