/*
 * Copyright (C) ST-Ericsson 2010 - 2013
 * Author: Martin Persson <martin.persson@stericsson.com>
 *         Hongbo Zhang <hongbo.zhang@linaro.org>
 * License Terms: GNU General Public License v2
 *
 * When the AB8500 thermal warning temperature is reached (threshold cannot
 * be changed by SW), an interrupt is set, and if no further action is taken
 * within a certain time frame, kernel_power_off will be called.
 *
 * When AB8500 thermal shutdown temperature is reached a hardware shutdown of
 * the AB8500 will occur.
 */

#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500-bm.h>
#include <linux/mfd/abx500/ab8500-gpadc.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/power/ab8500.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include "abx500.h"

#define DEFAULT_POWER_OFF_DELAY (HZ * 10)
#define THERMAL_VCC             1800
#define PULL_UP_RESISTOR        47000
/* Number of monitored sensors should not greater than NUM_SENSORS */
#define NUM_MONITORED_SENSORS   4

struct ab8500_gpadc_cfg {
        const struct abx500_res_to_temp *temp_tbl;
        int tbl_sz;
        int vcc;
        int r_up;
};

struct ab8500_temp {
        struct ab8500_gpadc *gpadc;
        struct ab8500_btemp *btemp;
        struct delayed_work power_off_work;
        struct ab8500_gpadc_cfg cfg;
        struct abx500_temp *abx500_data;
};

/*
 * The hardware connection is like this:
 * VCC----[ R_up ]-----[ NTC ]----GND
 * where R_up is pull-up resistance, and GPADC measures voltage on NTC.
 * and res_to_temp table is strictly sorted by falling resistance values.
 */
static int ab8500_voltage_to_temp(struct ab8500_gpadc_cfg *cfg,
                int v_ntc, int *temp)
{
        int r_ntc, i = 0, tbl_sz = cfg->tbl_sz;
        const struct abx500_res_to_temp *tbl = cfg->temp_tbl;

        if (cfg->vcc < 0 || v_ntc >= cfg->vcc)
                return -EINVAL;

        r_ntc = v_ntc * cfg->r_up / (cfg->vcc - v_ntc);
        if (r_ntc > tbl[0].resist || r_ntc < tbl[tbl_sz - 1].resist)
                return -EINVAL;

        while (!(r_ntc <= tbl[i].resist && r_ntc > tbl[i + 1].resist) &&
                        i < tbl_sz - 2)
                i++;

        /* return milli-Celsius */
        *temp = tbl[i].temp * 1000 + ((tbl[i + 1].temp - tbl[i].temp) * 1000 *
                (r_ntc - tbl[i].resist)) / (tbl[i + 1].resist - tbl[i].resist);

        return 0;
}

static int ab8500_read_sensor(struct abx500_temp *data, u8 sensor, int *temp)
{
        int voltage, ret;
        struct ab8500_temp *ab8500_data = data->plat_data;

        if (sensor == BAT_CTRL) {
                *temp = ab8500_btemp_get_batctrl_temp(ab8500_data->btemp);
        } else if (sensor == BTEMP_BALL) {
                *temp = ab8500_btemp_get_temp(ab8500_data->btemp);
        } else {
                voltage = ab8500_gpadc_convert(ab8500_data->gpadc, sensor);
                if (voltage < 0)
                        return voltage;

                ret = ab8500_voltage_to_temp(&ab8500_data->cfg, voltage, temp);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static void ab8500_thermal_power_off(struct work_struct *work)
{
        struct ab8500_temp *ab8500_data = container_of(work,
                                struct ab8500_temp, power_off_work.work);
        struct abx500_temp *abx500_data = ab8500_data->abx500_data;

        dev_warn(&abx500_data->pdev->dev, "Power off due to critical temp\n");

        kernel_power_off();
}

static ssize_t ab8500_show_name(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        return sprintf(buf, "ab8500\n");
}

static ssize_t ab8500_show_label(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        char *label;
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        int index = attr->index;

        switch (index) {
        case 1:
                label = "ext_adc1";
                break;
        case 2:
                label = "ext_adc2";
                break;
        case 3:
                label = "bat_temp";
                break;
        case 4:
                label = "bat_ctrl";
                break;
        default:
                return -EINVAL;
        }

        return sprintf(buf, "%s\n", label);
}

static int ab8500_temp_irq_handler(int irq, struct abx500_temp *data)
{
        struct ab8500_temp *ab8500_data = data->plat_data;

        dev_warn(&data->pdev->dev, "Power off in %d s\n",
                 DEFAULT_POWER_OFF_DELAY / HZ);

        schedule_delayed_work(&ab8500_data->power_off_work,
                DEFAULT_POWER_OFF_DELAY);
        return 0;
}

int abx500_hwmon_init(struct abx500_temp *data)
{
        struct ab8500_temp *ab8500_data;

        ab8500_data = devm_kzalloc(&data->pdev->dev, sizeof(*ab8500_data),
                GFP_KERNEL);
        if (!ab8500_data)
                return -ENOMEM;

        ab8500_data->gpadc = ab8500_gpadc_get("ab8500-gpadc.0");
        if (IS_ERR(ab8500_data->gpadc))
                return PTR_ERR(ab8500_data->gpadc);

        ab8500_data->btemp = ab8500_btemp_get();
        if (IS_ERR(ab8500_data->btemp))
                return PTR_ERR(ab8500_data->btemp);

        INIT_DELAYED_WORK(&ab8500_data->power_off_work,
                          ab8500_thermal_power_off);

        ab8500_data->cfg.vcc = THERMAL_VCC;
        ab8500_data->cfg.r_up = PULL_UP_RESISTOR;
        ab8500_data->cfg.temp_tbl = ab8500_temp_tbl_a_thermistor;
        ab8500_data->cfg.tbl_sz = ab8500_temp_tbl_a_size;

        data->plat_data = ab8500_data;

        /*
         * ADC_AUX1 and ADC_AUX2, connected to external NTC
         * BTEMP_BALL and BAT_CTRL, fixed usage
         */
        data->gpadc_addr[0] = ADC_AUX1;
        data->gpadc_addr[1] = ADC_AUX2;
        data->gpadc_addr[2] = BTEMP_BALL;
        data->gpadc_addr[3] = BAT_CTRL;
        data->monitored_sensors = NUM_MONITORED_SENSORS;

        data->ops.read_sensor = ab8500_read_sensor;
        data->ops.irq_handler = ab8500_temp_irq_handler;
        data->ops.show_name = ab8500_show_name;
        data->ops.show_label = ab8500_show_label;
        data->ops.is_visible = NULL;

        return 0;
}
EXPORT_SYMBOL(abx500_hwmon_init);

MODULE_AUTHOR("Hongbo Zhang <hongbo.zhang@linaro.org>");
MODULE_DESCRIPTION("AB8500 temperature driver");
MODULE_LICENSE("GPL");