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