linux/drivers/hwmon/ab8500.c
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   1/*
   2 * Copyright (C) ST-Ericsson 2010 - 2013
   3 * Author: Martin Persson <martin.persson@stericsson.com>
   4 *         Hongbo Zhang <hongbo.zhang@linaro.org>
   5 * License Terms: GNU General Public License v2
   6 *
   7 * When the AB8500 thermal warning temperature is reached (threshold cannot
   8 * be changed by SW), an interrupt is set, and if no further action is taken
   9 * within a certain time frame, pm_power off will be called.
  10 *
  11 * When AB8500 thermal shutdown temperature is reached a hardware shutdown of
  12 * the AB8500 will occur.
  13 */
  14
  15#include <linux/err.h>
  16#include <linux/hwmon.h>
  17#include <linux/hwmon-sysfs.h>
  18#include <linux/mfd/abx500.h>
  19#include <linux/mfd/abx500/ab8500-bm.h>
  20#include <linux/mfd/abx500/ab8500-gpadc.h>
  21#include <linux/module.h>
  22#include <linux/platform_device.h>
  23#include <linux/power/ab8500.h>
  24#include <linux/slab.h>
  25#include <linux/sysfs.h>
  26#include "abx500.h"
  27
  28#define DEFAULT_POWER_OFF_DELAY (HZ * 10)
  29#define THERMAL_VCC             1800
  30#define PULL_UP_RESISTOR        47000
  31/* Number of monitored sensors should not greater than NUM_SENSORS */
  32#define NUM_MONITORED_SENSORS   4
  33
  34struct ab8500_gpadc_cfg {
  35        const struct abx500_res_to_temp *temp_tbl;
  36        int tbl_sz;
  37        int vcc;
  38        int r_up;
  39};
  40
  41struct ab8500_temp {
  42        struct ab8500_gpadc *gpadc;
  43        struct ab8500_btemp *btemp;
  44        struct delayed_work power_off_work;
  45        struct ab8500_gpadc_cfg cfg;
  46        struct abx500_temp *abx500_data;
  47};
  48
  49/*
  50 * The hardware connection is like this:
  51 * VCC----[ R_up ]-----[ NTC ]----GND
  52 * where R_up is pull-up resistance, and GPADC measures voltage on NTC.
  53 * and res_to_temp table is strictly sorted by falling resistance values.
  54 */
  55static int ab8500_voltage_to_temp(struct ab8500_gpadc_cfg *cfg,
  56                int v_ntc, int *temp)
  57{
  58        int r_ntc, i = 0, tbl_sz = cfg->tbl_sz;
  59        const struct abx500_res_to_temp *tbl = cfg->temp_tbl;
  60
  61        if (cfg->vcc < 0 || v_ntc >= cfg->vcc)
  62                return -EINVAL;
  63
  64        r_ntc = v_ntc * cfg->r_up / (cfg->vcc - v_ntc);
  65        if (r_ntc > tbl[0].resist || r_ntc < tbl[tbl_sz - 1].resist)
  66                return -EINVAL;
  67
  68        while (!(r_ntc <= tbl[i].resist && r_ntc > tbl[i + 1].resist) &&
  69                        i < tbl_sz - 2)
  70                i++;
  71
  72        /* return milli-Celsius */
  73        *temp = tbl[i].temp * 1000 + ((tbl[i + 1].temp - tbl[i].temp) * 1000 *
  74                (r_ntc - tbl[i].resist)) / (tbl[i + 1].resist - tbl[i].resist);
  75
  76        return 0;
  77}
  78
  79static int ab8500_read_sensor(struct abx500_temp *data, u8 sensor, int *temp)
  80{
  81        int voltage, ret;
  82        struct ab8500_temp *ab8500_data = data->plat_data;
  83
  84        if (sensor == BAT_CTRL) {
  85                *temp = ab8500_btemp_get_batctrl_temp(ab8500_data->btemp);
  86        } else if (sensor == BTEMP_BALL) {
  87                *temp = ab8500_btemp_get_temp(ab8500_data->btemp);
  88        } else {
  89                voltage = ab8500_gpadc_convert(ab8500_data->gpadc, sensor);
  90                if (voltage < 0)
  91                        return voltage;
  92
  93                ret = ab8500_voltage_to_temp(&ab8500_data->cfg, voltage, temp);
  94                if (ret < 0)
  95                        return ret;
  96        }
  97
  98        return 0;
  99}
 100
 101static void ab8500_thermal_power_off(struct work_struct *work)
 102{
 103        struct ab8500_temp *ab8500_data = container_of(work,
 104                                struct ab8500_temp, power_off_work.work);
 105        struct abx500_temp *abx500_data = ab8500_data->abx500_data;
 106
 107        dev_warn(&abx500_data->pdev->dev, "Power off due to critical temp\n");
 108
 109        pm_power_off();
 110}
 111
 112static ssize_t ab8500_show_name(struct device *dev,
 113                struct device_attribute *devattr, char *buf)
 114{
 115        return sprintf(buf, "ab8500\n");
 116}
 117
 118static ssize_t ab8500_show_label(struct device *dev,
 119                struct device_attribute *devattr, char *buf)
 120{
 121        char *label;
 122        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 123        int index = attr->index;
 124
 125        switch (index) {
 126        case 1:
 127                label = "ext_adc1";
 128                break;
 129        case 2:
 130                label = "ext_adc2";
 131                break;
 132        case 3:
 133                label = "bat_temp";
 134                break;
 135        case 4:
 136                label = "bat_ctrl";
 137                break;
 138        default:
 139                return -EINVAL;
 140        }
 141
 142        return sprintf(buf, "%s\n", label);
 143}
 144
 145static int ab8500_temp_irq_handler(int irq, struct abx500_temp *data)
 146{
 147        struct ab8500_temp *ab8500_data = data->plat_data;
 148
 149        dev_warn(&data->pdev->dev, "Power off in %d s\n",
 150                 DEFAULT_POWER_OFF_DELAY / HZ);
 151
 152        schedule_delayed_work(&ab8500_data->power_off_work,
 153                DEFAULT_POWER_OFF_DELAY);
 154        return 0;
 155}
 156
 157int abx500_hwmon_init(struct abx500_temp *data)
 158{
 159        struct ab8500_temp *ab8500_data;
 160
 161        ab8500_data = devm_kzalloc(&data->pdev->dev, sizeof(*ab8500_data),
 162                GFP_KERNEL);
 163        if (!ab8500_data)
 164                return -ENOMEM;
 165
 166        ab8500_data->gpadc = ab8500_gpadc_get("ab8500-gpadc.0");
 167        if (IS_ERR(ab8500_data->gpadc))
 168                return PTR_ERR(ab8500_data->gpadc);
 169
 170        ab8500_data->btemp = ab8500_btemp_get();
 171        if (IS_ERR(ab8500_data->btemp))
 172                return PTR_ERR(ab8500_data->btemp);
 173
 174        INIT_DELAYED_WORK(&ab8500_data->power_off_work,
 175                          ab8500_thermal_power_off);
 176
 177        ab8500_data->cfg.vcc = THERMAL_VCC;
 178        ab8500_data->cfg.r_up = PULL_UP_RESISTOR;
 179        ab8500_data->cfg.temp_tbl = ab8500_temp_tbl_a_thermistor;
 180        ab8500_data->cfg.tbl_sz = ab8500_temp_tbl_a_size;
 181
 182        data->plat_data = ab8500_data;
 183
 184        /*
 185         * ADC_AUX1 and ADC_AUX2, connected to external NTC
 186         * BTEMP_BALL and BAT_CTRL, fixed usage
 187         */
 188        data->gpadc_addr[0] = ADC_AUX1;
 189        data->gpadc_addr[1] = ADC_AUX2;
 190        data->gpadc_addr[2] = BTEMP_BALL;
 191        data->gpadc_addr[3] = BAT_CTRL;
 192        data->monitored_sensors = NUM_MONITORED_SENSORS;
 193
 194        data->ops.read_sensor = ab8500_read_sensor;
 195        data->ops.irq_handler = ab8500_temp_irq_handler;
 196        data->ops.show_name = ab8500_show_name;
 197        data->ops.show_label = ab8500_show_label;
 198        data->ops.is_visible = NULL;
 199
 200        return 0;
 201}
 202EXPORT_SYMBOL(abx500_hwmon_init);
 203
 204MODULE_AUTHOR("Hongbo Zhang <hongbo.zhang@linaro.org>");
 205MODULE_DESCRIPTION("AB8500 temperature driver");
 206MODULE_LICENSE("GPL");
 207
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