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, 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
  34 struct 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
  41 struct 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  */
  55 static 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
  79 static 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
 101 static 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
 112 static ssize_t ab8500_show_name(struct device *dev,
 113                 struct device_attribute *devattr, char *buf)
 114 {
 115         return sprintf(buf, "ab8500\n");
 116 }
 117
 118 static 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
 145 static 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
 157 int 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 }
 202 EXPORT_SYMBOL(abx500_hwmon_init);
 203
 204 MODULE_AUTHOR("Hongbo Zhang <hongbo.zhang@linaro.org>");
 205 MODULE_DESCRIPTION("AB8500 temperature driver");
 206 MODULE_LICENSE("GPL");