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>

3 files changed, 259 insertions, 0 deletions

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 49a89397231..5c3237f601d 100644
--- a/drivers/power/Kconfig
+++ b/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
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index b949cf85590..bc81fe2112c 100644
--- a/drivers/power/Makefile
+++ b/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
diff --git a/drivers/power/rx51_battery.c b/drivers/power/rx51_battery.c
new file mode 100644
index 00000000000..ca49d6c0ee9
--- /dev/null
+++ b/drivers/power/rx51_battery.c
@@ -0,0 +1,251 @@
+/*
+ * 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: