/*
 * intel_mid_thermal.c - Intel MID platform thermal driver
 *
 * Copyright (C) 2011 Intel Corporation
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * 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; version 2 of the License.
 *
 * 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.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Author: Durgadoss R <durgadoss.r@intel.com>
 */

#define pr_fmt(fmt) "intel_mid_thermal: " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/param.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/pm.h>
#include <linux/thermal.h>
#include <linux/mfd/intel_msic.h>

/* Number of thermal sensors */
#define MSIC_THERMAL_SENSORS    4

/* ADC1 - thermal registers */
#define MSIC_ADC_ENBL           0x10
#define MSIC_ADC_START          0x08

#define MSIC_ADCTHERM_ENBL      0x04
#define MSIC_ADCRRDATA_ENBL     0x05
#define MSIC_CHANL_MASK_VAL     0x0F

#define MSIC_STOPBIT_MASK       16
#define MSIC_ADCTHERM_MASK      4
/* Number of ADC channels */
#define ADC_CHANLS_MAX          15
#define ADC_LOOP_MAX            (ADC_CHANLS_MAX - MSIC_THERMAL_SENSORS)

/* ADC channel code values */
#define SKIN_SENSOR0_CODE       0x08
#define SKIN_SENSOR1_CODE       0x09
#define SYS_SENSOR_CODE         0x0A
#define MSIC_DIE_SENSOR_CODE    0x03

#define SKIN_THERM_SENSOR0      0
#define SKIN_THERM_SENSOR1      1
#define SYS_THERM_SENSOR2       2
#define MSIC_DIE_THERM_SENSOR3  3

/* ADC code range */
#define ADC_MAX                 977
#define ADC_MIN                 162
#define ADC_VAL0C               887
#define ADC_VAL20C              720
#define ADC_VAL40C              508
#define ADC_VAL60C              315

/* ADC base addresses */
#define ADC_CHNL_START_ADDR     INTEL_MSIC_ADC1ADDR0    /* increments by 1 */
#define ADC_DATA_START_ADDR     INTEL_MSIC_ADC1SNS0H    /* increments by 2 */

/* MSIC die attributes */
#define MSIC_DIE_ADC_MIN        488
#define MSIC_DIE_ADC_MAX        1004

/* This holds the address of the first free ADC channel,
 * among the 15 channels
 */
static int channel_index;

struct platform_info {
        struct platform_device *pdev;
        struct thermal_zone_device *tzd[MSIC_THERMAL_SENSORS];
};

struct thermal_device_info {
        unsigned int chnl_addr;
        int direct;
        /* This holds the current temperature in millidegree celsius */
        long curr_temp;
};

/**
 * to_msic_die_temp - converts adc_val to msic_die temperature
 * @adc_val: ADC value to be converted
 *
 * Can sleep
 */
static int to_msic_die_temp(uint16_t adc_val)
{
        return (368 * (adc_val) / 1000) - 220;
}

/**
 * is_valid_adc - checks whether the adc code is within the defined range
 * @min: minimum value for the sensor
 * @max: maximum value for the sensor
 *
 * Can sleep
 */
static int is_valid_adc(uint16_t adc_val, uint16_t min, uint16_t max)
{
        return (adc_val >= min) && (adc_val <= max);
}

/**
 * adc_to_temp - converts the ADC code to temperature in C
 * @direct: true if ths channel is direct index
 * @adc_val: the adc_val that needs to be converted
 * @tp: temperature return value
 *
 * Linear approximation is used to covert the skin adc value into temperature.
 * This technique is used to avoid very long look-up table to get
 * the appropriate temp value from ADC value.
 * The adc code vs sensor temp curve is split into five parts
 * to achieve very close approximate temp value with less than
 * 0.5C error
 */
static int adc_to_temp(int direct, uint16_t adc_val, int *tp)
{
        int temp;

        /* Direct conversion for die temperature */
        if (direct) {
                if (is_valid_adc(adc_val, MSIC_DIE_ADC_MIN, MSIC_DIE_ADC_MAX)) {
                        *tp = to_msic_die_temp(adc_val) * 1000;
                        return 0;
                }
                return -ERANGE;
        }

        if (!is_valid_adc(adc_val, ADC_MIN, ADC_MAX))
                return -ERANGE;

        /* Linear approximation for skin temperature */
        if (adc_val > ADC_VAL0C)
                temp = 177 - (adc_val/5);
        else if ((adc_val <= ADC_VAL0C) && (adc_val > ADC_VAL20C))
                temp = 111 - (adc_val/8);
        else if ((adc_val <= ADC_VAL20C) && (adc_val > ADC_VAL40C))
                temp = 92 - (adc_val/10);
        else if ((adc_val <= ADC_VAL40C) && (adc_val > ADC_VAL60C))
                temp = 91 - (adc_val/10);
        else
                temp = 112 - (adc_val/6);

        /* Convert temperature in celsius to milli degree celsius */
        *tp = temp * 1000;
        return 0;
}

/**
 * mid_read_temp - read sensors for temperature
 * @temp: holds the current temperature for the sensor after reading
 *
 * reads the adc_code from the channel and converts it to real
 * temperature. The converted value is stored in temp.
 *
 * Can sleep
 */
static int mid_read_temp(struct thermal_zone_device *tzd, int *temp)
{
        struct thermal_device_info *td_info = tzd->devdata;
        uint16_t adc_val, addr;
        uint8_t data = 0;
        int ret;
        int curr_temp;

        addr = td_info->chnl_addr;

        /* Enable the msic for conversion before reading */
        ret = intel_msic_reg_write(INTEL_MSIC_ADC1CNTL3, MSIC_ADCRRDATA_ENBL);
        if (ret)
                return ret;

        /* Re-toggle the RRDATARD bit (temporary workaround) */
        ret = intel_msic_reg_write(INTEL_MSIC_ADC1CNTL3, MSIC_ADCTHERM_ENBL);
        if (ret)
                return ret;

        /* Read the higher bits of data */
        ret = intel_msic_reg_read(addr, &data);
        if (ret)
                return ret;

        /* Shift bits to accommodate the lower two data bits */
        adc_val = (data << 2);
        addr++;

        ret = intel_msic_reg_read(addr, &data);/* Read lower bits */
        if (ret)
                return ret;

        /* Adding lower two bits to the higher bits */
        data &= 03;
        adc_val += data;

        /* Convert ADC value to temperature */
        ret = adc_to_temp(td_info->direct, adc_val, &curr_temp);
        if (ret == 0)
                *temp = td_info->curr_temp = curr_temp;
        return ret;
}

/**
 * configure_adc - enables/disables the ADC for conversion
 * @val: zero: disables the ADC non-zero:enables the ADC
 *
 * Enable/Disable the ADC depending on the argument
 *
 * Can sleep
 */
static int configure_adc(int val)
{
        int ret;
        uint8_t data;

        ret = intel_msic_reg_read(INTEL_MSIC_ADC1CNTL1, &data);
        if (ret)
                return ret;

        if (val) {
                /* Enable and start the ADC */
                data |= (MSIC_ADC_ENBL | MSIC_ADC_START);
        } else {
                /* Just stop the ADC */
                data &= (~MSIC_ADC_START);
        }
        return intel_msic_reg_write(INTEL_MSIC_ADC1CNTL1, data);
}

/**
 * set_up_therm_channel - enable thermal channel for conversion
 * @base_addr: index of free msic ADC channel
 *
 * Enable all the three channels for conversion
 *
 * Can sleep
 */
static int set_up_therm_channel(u16 base_addr)
{
        int ret;

        /* Enable all the sensor channels */
        ret = intel_msic_reg_write(base_addr, SKIN_SENSOR0_CODE);
        if (ret)
                return ret;

        ret = intel_msic_reg_write(base_addr + 1, SKIN_SENSOR1_CODE);
        if (ret)
                return ret;

        ret = intel_msic_reg_write(base_addr + 2, SYS_SENSOR_CODE);
        if (ret)
                return ret;

        /* Since this is the last channel, set the stop bit
         * to 1 by ORing the DIE_SENSOR_CODE with 0x10 */
        ret = intel_msic_reg_write(base_addr + 3,
                        (MSIC_DIE_SENSOR_CODE | 0x10));
        if (ret)
                return ret;

        /* Enable ADC and start it */
        return configure_adc(1);
}

/**
 * reset_stopbit - sets the stop bit to 0 on the given channel
 * @addr: address of the channel
 *
 * Can sleep
 */
static int reset_stopbit(uint16_t addr)
{
        int ret;
        uint8_t data;
        ret = intel_msic_reg_read(addr, &data);
        if (ret)
                return ret;
        /* Set the stop bit to zero */
        return intel_msic_reg_write(addr, (data & 0xEF));
}

/**
 * find_free_channel - finds an empty channel for conversion
 *
 * If the ADC is not enabled then start using 0th channel
 * itself. Otherwise find an empty channel by looking for a
 * channel in which the stopbit is set to 1. returns the index
 * of the first free channel if succeeds or an error code.
 *
 * Context: can sleep
 *
 * FIXME: Ultimately the channel allocator will move into the intel_scu_ipc
 * code.
 */
static int find_free_channel(void)
{
        int ret;
        int i;
        uint8_t data;

        /* check whether ADC is enabled */
        ret = intel_msic_reg_read(INTEL_MSIC_ADC1CNTL1, &data);
        if (ret)
                return ret;

        if ((data & MSIC_ADC_ENBL) == 0)
                return 0;

        /* ADC is already enabled; Looking for an empty channel */
        for (i = 0; i < ADC_CHANLS_MAX; i++) {
                ret = intel_msic_reg_read(ADC_CHNL_START_ADDR + i, &data);
                if (ret)
                        return ret;

                if (data & MSIC_STOPBIT_MASK) {
                        ret = i;
                        break;
                }
        }
        return (ret > ADC_LOOP_MAX) ? (-EINVAL) : ret;
}

/**
 * mid_initialize_adc - initializing the ADC
 * @dev: our device structure
 *
 * Initialize the ADC for reading thermistor values. Can sleep.
 */
static int mid_initialize_adc(struct device *dev)
{
        u8  data;
        u16 base_addr;
        int ret;

        /*
         * Ensure that adctherm is disabled before we
         * initialize the ADC
         */
        ret = intel_msic_reg_read(INTEL_MSIC_ADC1CNTL3, &data);
        if (ret)
                return ret;

        data &= ~MSIC_ADCTHERM_MASK;
        ret = intel_msic_reg_write(INTEL_MSIC_ADC1CNTL3, data);
        if (ret)
                return ret;

        /* Index of the first channel in which the stop bit is set */
        channel_index = find_free_channel();
        if (channel_index < 0) {
                dev_err(dev, "No free ADC channels");
                return channel_index;
        }

        base_addr = ADC_CHNL_START_ADDR + channel_index;

        if (!(channel_index == 0 || channel_index == ADC_LOOP_MAX)) {
                /* Reset stop bit for channels other than 0 and 12 */
                ret = reset_stopbit(base_addr);
                if (ret)
                        return ret;

                /* Index of the first free channel */
                base_addr++;
                channel_index++;
        }

        ret = set_up_therm_channel(base_addr);
        if (ret) {
                dev_err(dev, "unable to enable ADC");
                return ret;
        }
        dev_dbg(dev, "ADC initialization successful");
        return ret;
}

/**
 * initialize_sensor - sets default temp and timer ranges
 * @index: index of the sensor
 *
 * Context: can sleep
 */
static struct thermal_device_info *initialize_sensor(int index)
{
        struct thermal_device_info *td_info =
                kzalloc(sizeof(struct thermal_device_info), GFP_KERNEL);

        if (!td_info)
                return NULL;

        /* Set the base addr of the channel for this sensor */
        td_info->chnl_addr = ADC_DATA_START_ADDR + 2 * (channel_index + index);
        /* Sensor 3 is direct conversion */
        if (index == 3)
                td_info->direct = 1;
        return td_info;
}

/**
 * mid_thermal_resume - resume routine
 * @dev: device structure
 *
 * mid thermal resume: re-initializes the adc. Can sleep.
 */
static int mid_thermal_resume(struct device *dev)
{
        return mid_initialize_adc(dev);
}

/**
 * mid_thermal_suspend - suspend routine
 * @dev: device structure
 *
 * mid thermal suspend implements the suspend functionality
 * by stopping the ADC. Can sleep.
 */
static int mid_thermal_suspend(struct device *dev)
{
        /*
         * This just stops the ADC and does not disable it.
         * temporary workaround until we have a generic ADC driver.
         * If 0 is passed, it disables the ADC.
         */
        return configure_adc(0);
}

static SIMPLE_DEV_PM_OPS(mid_thermal_pm,
                         mid_thermal_suspend, mid_thermal_resume);

/**
 * read_curr_temp - reads the current temperature and stores in temp
 * @temp: holds the current temperature value after reading
 *
 * Can sleep
 */
static int read_curr_temp(struct thermal_zone_device *tzd, int *temp)
{
        WARN_ON(tzd == NULL);
        return mid_read_temp(tzd, temp);
}

/* Can't be const */
static struct thermal_zone_device_ops tzd_ops = {
        .get_temp = read_curr_temp,
};

/**
 * mid_thermal_probe - mfld thermal initialize
 * @pdev: platform device structure
 *
 * mid thermal probe initializes the hardware and registers
 * all the sensors with the generic thermal framework. Can sleep.
 */
static int mid_thermal_probe(struct platform_device *pdev)
{
        static char *name[MSIC_THERMAL_SENSORS] = {
                "skin0", "skin1", "sys", "msicdie"
        };

        int ret;
        int i;
        struct platform_info *pinfo;

        pinfo = devm_kzalloc(&pdev->dev, sizeof(struct platform_info),
                             GFP_KERNEL);
        if (!pinfo)
                return -ENOMEM;

        /* Initializing the hardware */
        ret = mid_initialize_adc(&pdev->dev);
        if (ret) {
                dev_err(&pdev->dev, "ADC init failed");
                return ret;
        }

        /* Register each sensor with the generic thermal framework*/
        for (i = 0; i < MSIC_THERMAL_SENSORS; i++) {
                struct thermal_device_info *td_info = initialize_sensor(i);

                if (!td_info) {
                        ret = -ENOMEM;
                        goto err;
                }
                pinfo->tzd[i] = thermal_zone_device_register(name[i],
                                0, 0, td_info, &tzd_ops, NULL, 0, 0);
                if (IS_ERR(pinfo->tzd[i])) {
                        kfree(td_info);
                        ret = PTR_ERR(pinfo->tzd[i]);
                        goto err;
                }
        }

        pinfo->pdev = pdev;
        platform_set_drvdata(pdev, pinfo);
        return 0;

err:
        while (--i >= 0) {
                kfree(pinfo->tzd[i]->devdata);
                thermal_zone_device_unregister(pinfo->tzd[i]);
        }
        configure_adc(0);
        return ret;
}

/**
 * mid_thermal_remove - mfld thermal finalize
 * @dev: platform device structure
 *
 * MLFD thermal remove unregisters all the sensors from the generic
 * thermal framework. Can sleep.
 */
static int mid_thermal_remove(struct platform_device *pdev)
{
        int i;
        struct platform_info *pinfo = platform_get_drvdata(pdev);

        for (i = 0; i < MSIC_THERMAL_SENSORS; i++) {
                kfree(pinfo->tzd[i]->devdata);
                thermal_zone_device_unregister(pinfo->tzd[i]);
        }

        /* Stop the ADC */
        return configure_adc(0);
}

#define DRIVER_NAME "msic_thermal"

static const struct platform_device_id therm_id_table[] = {
        { DRIVER_NAME, 1 },
        { "msic_thermal", 1 },
        { }
};

static struct platform_driver mid_thermal_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .pm = &mid_thermal_pm,
        },
        .probe = mid_thermal_probe,
        .remove = mid_thermal_remove,
        .id_table = therm_id_table,
};

module_platform_driver(mid_thermal_driver);

MODULE_AUTHOR("Durgadoss R <durgadoss.r@intel.com>");
MODULE_DESCRIPTION("Intel Medfield Platform Thermal Driver");
MODULE_LICENSE("GPL");