power_supply: Add new Nokia RX-51 (N900) power supply battery driver

This driver exporting battery design capacity, temperature and voltage for
battery in Nokia RX-51. This driver is needed for open source battery
management on Nokia RX-51 (N900).
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

drivers/power/Kconfig

@@ -245,6 +245,13 @@ config BATTERY_INTEL_MID
 	  Say Y here to enable the battery driver on Intel MID
 	  platforms.
 
+config BATTERY_RX51
+	tristate "Nokia RX-51 (N900) battery driver"
+	depends on TWL4030_MADC
+	help
+	  Say Y here to enable support for battery information on Nokia
+	  RX-51, also known as N900 tablet.
+
 config CHARGER_ISP1704
 	tristate "ISP1704 USB Charger Detection"
 	depends on USB_OTG_UTILS

drivers/power/Makefile

@@ -37,6 +37,7 @@ obj-$(CONFIG_CHARGER_88PM860X)	+= 88pm860x_charger.o
 obj-$(CONFIG_CHARGER_PCF50633)	+= pcf50633-charger.o
 obj-$(CONFIG_BATTERY_JZ4740)	+= jz4740-battery.o
 obj-$(CONFIG_BATTERY_INTEL_MID)	+= intel_mid_battery.o
+obj-$(CONFIG_BATTERY_RX51)	+= rx51_battery.o
 obj-$(CONFIG_AB8500_BM)		+= ab8500_charger.o ab8500_btemp.o ab8500_fg.o abx500_chargalg.o
 obj-$(CONFIG_CHARGER_ISP1704)	+= isp1704_charger.o
 obj-$(CONFIG_CHARGER_MAX8903)	+= max8903_charger.o

drivers/power/rx51_battery.c

+/*
+ * Nokia RX-51 battery driver
+ *
+ * Copyright (C) 2012  Pali Rohár <pali.rohar@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/module.h>
+#include <linux/param.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+#include <linux/i2c/twl4030-madc.h>
+
+struct rx51_device_info {
+	struct device *dev;
+	struct power_supply bat;
+};
+
+/*
+ * Read ADCIN channel value, code copied from maemo kernel
+ */
+static int rx51_battery_read_adc(int channel)
+{
+	struct twl4030_madc_request req;
+
+	req.channels = 1 << channel;
+	req.do_avg = 1;
+	req.method = TWL4030_MADC_SW1;
+	req.func_cb = NULL;
+	req.type = TWL4030_MADC_WAIT;
+
+	if (twl4030_madc_conversion(&req) <= 0)
+		return -ENODATA;
+
+	return req.rbuf[channel];
+}
+
+/*
+ * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
+ * This conversion formula was extracted from maemo program bsi-read
+ */
+static int rx51_battery_read_voltage(struct rx51_device_info *di)
+{
+	int voltage = rx51_battery_read_adc(12);
+
+	if (voltage < 0)
+		return voltage;
+
+	return 1000 * (10000 * voltage / 1705);
+}
+
+/*
+ * Temperature look-up tables
+ * TEMP = (1/(t1 + 1/298) - 273.15)
+ * Where t1 = (1/B) * ln((RAW_ADC_U * 2.5)/(R * I * 255))
+ * Formula is based on experimental data, RX-51 CAL data, maemo program bme
+ * and formula from da9052 driver with values R = 100, B = 3380, I = 0.00671
+ */
+
+/*
+ * Table1 (temperature for first 25 RAW values)
+ * Usage: TEMP = rx51_temp_table1[RAW]
+ *   RAW is between 1 and 24
+ *   TEMP is between 201 C and 55 C
+ */
+static u8 rx51_temp_table1[] = {
+	255, 201, 159, 138, 124, 114, 106,  99,  94,  89,  85,  82,  78,  75,
+	 73,  70,  68,  66,  64,  62,  61,  59,  57,  56,  55
+};
+
+/*
+ * Table2 (lowest RAW value for temperature)
+ * Usage: RAW = rx51_temp_table2[TEMP-rx51_temp_table2_first]
+ *   TEMP is between 53 C and -32 C
+ *   RAW is between 25 and 993
+ */
+#define rx51_temp_table2_first 53
+static u16 rx51_temp_table2[] = {
+	 25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,  37,  39,
+	 40,  41,  43,  44,  46,  48,  49,  51,  53,  55,  57,  59,  61,  64,
+	 66,  69,  71,  74,  77,  80,  83,  86,  90,  94,  97, 101, 106, 110,
+	115, 119, 125, 130, 136, 141, 148, 154, 161, 168, 176, 184, 202, 211,
+	221, 231, 242, 254, 266, 279, 293, 308, 323, 340, 357, 375, 395, 415,
+	437, 460, 485, 511, 539, 568, 600, 633, 669, 706, 747, 790, 836, 885,
+	937, 993, 1024
+};
+
+/*
+ * Read ADCIN channel 0 (battery temp) and convert value to tenths of Celsius
+ * Use Temperature look-up tables for conversation
+ */
+static int rx51_battery_read_temperature(struct rx51_device_info *di)
+{
+	int min = 0;
+	int max = ARRAY_SIZE(rx51_temp_table2) - 1;
+	int raw = rx51_battery_read_adc(0);
+
+	/* Zero and negative values are undefined */
+	if (raw <= 0)
+		return INT_MAX;
+
+	/* ADC channels are 10 bit, higher value are undefined */
+	if (raw >= (1 << 10))
+		return INT_MIN;
+
+	/* First check for temperature in first direct table */
+	if (raw < ARRAY_SIZE(rx51_temp_table1))
+		return rx51_temp_table1[raw] * 100;
+
+	/* Binary search RAW value in second inverse table */
+	while (max - min > 1) {
+		int mid = (max + min) / 2;
+		if (rx51_temp_table2[mid] <= raw)
+			min = mid;
+		else if (rx51_temp_table2[mid] > raw)
+			max = mid;
+		if (rx51_temp_table2[mid] == raw)
+			break;
+	}
+
+	return (rx51_temp_table2_first - min) * 100;
+}
+
+/*
+ * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
+ * This conversion formula was extracted from maemo program bsi-read
+ */
+static int rx51_battery_read_capacity(struct rx51_device_info *di)
+{
+	int capacity = rx51_battery_read_adc(4);
+
+	if (capacity < 0)
+		return capacity;
+
+	return 1280 * (1200 * capacity)/(1024 - capacity);
+}
+
+/*
+ * Return power_supply property
+ */
+static int rx51_battery_get_property(struct power_supply *psy,
+					enum power_supply_property psp,
+					union power_supply_propval *val)
+{
+	struct rx51_device_info *di = container_of((psy),
+				struct rx51_device_info, bat);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
+		val->intval = 4200000;
+		break;
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		val->intval = rx51_battery_read_voltage(di);
+		break;
+	case POWER_SUPPLY_PROP_TEMP:
+		val->intval = rx51_battery_read_temperature(di);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		val->intval = rx51_battery_read_capacity(di);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (val->intval == INT_MAX || val->intval == INT_MIN)
+		return -EINVAL;
+
+	return 0;
+}
+
+static enum power_supply_property rx51_battery_props[] = {
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+};
+
+static int __devinit rx51_battery_probe(struct platform_device *pdev)
+{
+	struct rx51_device_info *di;
+	int ret;
+
+	di = kzalloc(sizeof(*di), GFP_KERNEL);
+	if (!di)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, di);
+
+	di->bat.name = dev_name(&pdev->dev);
+	di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
+	di->bat.properties = rx51_battery_props;
+	di->bat.num_properties = ARRAY_SIZE(rx51_battery_props);
+	di->bat.get_property = rx51_battery_get_property;
+
+	ret = power_supply_register(di->dev, &di->bat);
+	if (ret) {
+		platform_set_drvdata(pdev, NULL);
+		kfree(di);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __devexit rx51_battery_remove(struct platform_device *pdev)
+{
+	struct rx51_device_info *di = platform_get_drvdata(pdev);
+
+	power_supply_unregister(&di->bat);
+	platform_set_drvdata(pdev, NULL);
+	kfree(di);
+
+	return 0;
+}
+
+static struct platform_driver rx51_battery_driver = {
+	.probe = rx51_battery_probe,
+	.remove = __devexit_p(rx51_battery_remove),
+	.driver = {
+		.name = "rx51-battery",
+		.owner = THIS_MODULE,
+	},
+};
+module_platform_driver(rx51_battery_driver);
+
+MODULE_ALIAS("platform:rx51-battery");
+MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_DESCRIPTION("Nokia RX-51 battery driver");
+MODULE_LICENSE("GPL");