drivers/hwmon/ab8500.c

   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, kernel_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/reboot.h>
  25 #include <linux/slab.h>
  26 #include <linux/sysfs.h>
  27 #include "abx500.h"
  28
  29 #define DEFAULT_POWER_OFF_DELAY (HZ * 10)
  30 #define THERMAL_VCC             1800
  31 #define PULL_UP_RESISTOR        47000
  32 /* Number of monitored sensors should not greater than NUM_SENSORS */
  33 #define NUM_MONITORED_SENSORS   4
  34
  35 struct ab8500_gpadc_cfg {
  36         const struct abx500_res_to_temp *temp_tbl;
  37         int tbl_sz;
  38         int vcc;
  39         int r_up;
  40 };
  41
  42 struct ab8500_temp {
  43         struct ab8500_gpadc *gpadc;
  44         struct ab8500_btemp *btemp;
  45         struct delayed_work power_off_work;
  46         struct ab8500_gpadc_cfg cfg;
  47         struct abx500_temp *abx500_data;
  48 };
  49
  50 /*
  51  * The hardware connection is like this:
  52  * VCC----[ R_up ]-----[ NTC ]----GND
  53  * where R_up is pull-up resistance, and GPADC measures voltage on NTC.
  54  * and res_to_temp table is strictly sorted by falling resistance values.
  55  */
  56 static int ab8500_voltage_to_temp(struct ab8500_gpadc_cfg *cfg,
  57                 int v_ntc, int *temp)
  58 {
  59         int r_ntc, i = 0, tbl_sz = cfg->tbl_sz;
  60         const struct abx500_res_to_temp *tbl = cfg->temp_tbl;
  61
  62         if (cfg->vcc < 0 || v_ntc >= cfg->vcc)
  63                 return -EINVAL;
  64
  65         r_ntc = v_ntc * cfg->r_up / (cfg->vcc - v_ntc);
  66         if (r_ntc > tbl[0].resist || r_ntc < tbl[tbl_sz - 1].resist)
  67                 return -EINVAL;
  68
  69         while (!(r_ntc <= tbl[i].resist && r_ntc > tbl[i + 1].resist) &&
  70                         i < tbl_sz - 2)
  71                 i++;
  72
  73         /* return milli-Celsius */
  74         *temp = tbl[i].temp * 1000 + ((tbl[i + 1].temp - tbl[i].temp) * 1000 *
  75                 (r_ntc - tbl[i].resist)) / (tbl[i + 1].resist - tbl[i].resist);
  76
  77         return 0;
  78 }
  79
  80 static int ab8500_read_sensor(struct abx500_temp *data, u8 sensor, int *temp)
  81 {
  82         int voltage, ret;
  83         struct ab8500_temp *ab8500_data = data->plat_data;
  84
  85         if (sensor == BAT_CTRL) {
  86                 *temp = ab8500_btemp_get_batctrl_temp(ab8500_data->btemp);
  87         } else if (sensor == BTEMP_BALL) {
  88                 *temp = ab8500_btemp_get_temp(ab8500_data->btemp);
  89         } else {
  90                 voltage = ab8500_gpadc_convert(ab8500_data->gpadc, sensor);
  91                 if (voltage < 0)
  92                         return voltage;
  93
  94                 ret = ab8500_voltage_to_temp(&ab8500_data->cfg, voltage, temp);
  95                 if (ret < 0)
  96                         return ret;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static void ab8500_thermal_power_off(struct work_struct *work)
 103 {
 104         struct ab8500_temp *ab8500_data = container_of(work,
 105                                 struct ab8500_temp, power_off_work.work);
 106         struct abx500_temp *abx500_data = ab8500_data->abx500_data;
 107
 108         dev_warn(&abx500_data->pdev->dev, "Power off due to critical temp\n");
 109
 110         kernel_power_off();
 111 }
 112
 113 static ssize_t ab8500_show_name(struct device *dev,
 114                 struct device_attribute *devattr, char *buf)
 115 {
 116         return sprintf(buf, "ab8500\n");
 117 }
 118
 119 static ssize_t ab8500_show_label(struct device *dev,
 120                 struct device_attribute *devattr, char *buf)
 121 {
 122         char *label;
 123         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 124         int index = attr->index;
 125
 126         switch (index) {
 127         case 1:
 128                 label = "ext_adc1";
 129                 break;
 130         case 2:
 131                 label = "ext_adc2";
 132                 break;
 133         case 3:
 134                 label = "bat_temp";
 135                 break;
 136         case 4:
 137                 label = "bat_ctrl";
 138                 break;
 139         default:
 140                 return -EINVAL;
 141         }
 142
 143         return sprintf(buf, "%s\n", label);
 144 }
 145
 146 static int ab8500_temp_irq_handler(int irq, struct abx500_temp *data)
 147 {
 148         struct ab8500_temp *ab8500_data = data->plat_data;
 149
 150         dev_warn(&data->pdev->dev, "Power off in %d s\n",
 151                  DEFAULT_POWER_OFF_DELAY / HZ);
 152
 153         schedule_delayed_work(&ab8500_data->power_off_work,
 154                 DEFAULT_POWER_OFF_DELAY);
 155         return 0;
 156 }
 157
 158 int abx500_hwmon_init(struct abx500_temp *data)
 159 {
 160         struct ab8500_temp *ab8500_data;
 161
 162         ab8500_data = devm_kzalloc(&data->pdev->dev, sizeof(*ab8500_data),
 163                 GFP_KERNEL);
 164         if (!ab8500_data)
 165                 return -ENOMEM;
 166
 167         ab8500_data->gpadc = ab8500_gpadc_get("ab8500-gpadc.0");
 168         if (IS_ERR(ab8500_data->gpadc))
 169                 return PTR_ERR(ab8500_data->gpadc);
 170
 171         ab8500_data->btemp = ab8500_btemp_get();
 172         if (IS_ERR(ab8500_data->btemp))
 173                 return PTR_ERR(ab8500_data->btemp);
 174
 175         INIT_DELAYED_WORK(&ab8500_data->power_off_work,
 176                           ab8500_thermal_power_off);
 177
 178         ab8500_data->cfg.vcc = THERMAL_VCC;
 179         ab8500_data->cfg.r_up = PULL_UP_RESISTOR;
 180         ab8500_data->cfg.temp_tbl = ab8500_temp_tbl_a_thermistor;
 181         ab8500_data->cfg.tbl_sz = ab8500_temp_tbl_a_size;
 182
 183         data->plat_data = ab8500_data;
 184
 185         /*
 186          * ADC_AUX1 and ADC_AUX2, connected to external NTC
 187          * BTEMP_BALL and BAT_CTRL, fixed usage
 188          */
 189         data->gpadc_addr[0] = ADC_AUX1;
 190         data->gpadc_addr[1] = ADC_AUX2;
 191         data->gpadc_addr[2] = BTEMP_BALL;
 192         data->gpadc_addr[3] = BAT_CTRL;
 193         data->monitored_sensors = NUM_MONITORED_SENSORS;
 194
 195         data->ops.read_sensor = ab8500_read_sensor;
 196         data->ops.irq_handler = ab8500_temp_irq_handler;
 197         data->ops.show_name = ab8500_show_name;
 198         data->ops.show_label = ab8500_show_label;
 199         data->ops.is_visible = NULL;
 200
 201         return 0;
 202 }
 203 EXPORT_SYMBOL(abx500_hwmon_init);
 204
 205 MODULE_AUTHOR("Hongbo Zhang <hongbo.zhang@linaro.org>");
 206 MODULE_DESCRIPTION("AB8500 temperature driver");
 207 MODULE_LICENSE("GPL");