/*
* ntc_thermistor.c - NTC Thermistors
*
* Copyright (C) 2010 Samsung Electronics
* MyungJoo Ham <myungjoo.ham@samsung.com>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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
*
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/math64.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/platform_data/ntc_thermistor.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
struct ntc_compensation {
int temp_C;
unsigned int ohm;
};
/*
* A compensation table should be sorted by the values of .ohm
* in descending order.
* The following compensation tables are from the specification of Murata NTC
* Thermistors Datasheet
*/
static const struct ntc_compensation ncpXXwb473[] = {
{ .temp_C = -40, .ohm = 1747920 },
{ .temp_C = -35, .ohm = 1245428 },
{ .temp_C = -30, .ohm = 898485 },
{ .temp_C = -25, .ohm = 655802 },
{ .temp_C = -20, .ohm = 483954 },
{ .temp_C = -15, .ohm = 360850 },
{ .temp_C = -10, .ohm = 271697 },
{ .temp_C = -5, .ohm = 206463 },
{ .temp_C = 0, .ohm = 158214 },
{ .temp_C = 5, .ohm = 122259 },
{ .temp_C = 10, .ohm = 95227 },
{ .temp_C = 15, .ohm = 74730 },
{ .temp_C = 20, .ohm = 59065 },
{ .temp_C = 25, .ohm = 47000 },
{ .temp_C = 30, .ohm = 37643 },
{ .temp_C = 35, .ohm = 30334 },
{ .temp_C = 40, .ohm = 24591 },
{ .temp_C = 45, .ohm = 20048 },
{ .temp_C = 50, .ohm = 16433 },
{ .temp_C = 55, .ohm = 13539 },
{ .temp_C = 60, .ohm = 11209 },
{ .temp_C = 65, .ohm = 9328 },
{ .temp_C = 70, .ohm = 7798 },
{ .temp_C = 75, .ohm = 6544 },
{ .temp_C = 80, .ohm = 5518 },
{ .temp_C = 85, .ohm = 4674 },
{ .temp_C = 90, .ohm = 3972 },
{ .temp_C = 95, .ohm = 3388 },
{ .temp_C = 100, .ohm = 2902 },
{ .temp_C = 105, .ohm = 2494 },
{ .temp_C = 110, .ohm = 2150 },
{ .temp_C = 115, .ohm = 1860 },
{ .temp_C = 120, .ohm = 1615 },
{ .temp_C = 125, .ohm = 1406 },
};
static const struct ntc_compensation ncpXXwl333[] = {
{ .temp_C = -40, .ohm = 1610154 },
{ .temp_C = -35, .ohm = 1130850 },
{ .temp_C = -30, .ohm = 802609 },
{ .temp_C = -25, .ohm = 575385 },
{ .temp_C = -20, .ohm = 416464 },
{ .temp_C = -15, .ohm = 304219 },
{ .temp_C = -10, .ohm = 224193 },
{ .temp_C = -5, .ohm = 166623 },
{ .temp_C = 0, .ohm = 124850 },
{ .temp_C = 5, .ohm = 94287 },
{ .temp_C = 10, .ohm = 71747 },
{ .temp_C = 15, .ohm = 54996 },
{ .temp_C = 20, .ohm = 42455 },
{ .temp_C = 25, .ohm = 33000 },
{ .temp_C = 30, .ohm = 25822 },
{ .temp_C = 35, .ohm = 20335 },
{ .temp_C = 40, .ohm = 16115 },
{ .temp_C = 45, .ohm = 12849 },
{ .temp_C = 50, .ohm = 10306 },
{ .temp_C = 55, .ohm = 8314 },
{ .temp_C = 60, .ohm = 6746 },
{ .temp_C = 65, .ohm = 5503 },
{ .temp_C = 70, .ohm = 4513 },
{ .temp_C = 75, .ohm = 3721 },
{ .temp_C = 80, .ohm = 3084 },
{ .temp_C = 85, .ohm = 2569 },
{ .temp_C = 90, .ohm = 2151 },
{ .temp_C = 95, .ohm = 1809 },
{ .temp_C = 100, .ohm = 1529 },
{ .temp_C = 105, .ohm = 1299 },
{ .temp_C = 110, .ohm = 1108 },
{ .temp_C = 115, .ohm = 949 },
{ .temp_C = 120, .ohm = 817 },
{ .temp_C = 125, .ohm = 707 },
};
struct ntc_data {
struct device *hwmon_dev;
struct ntc_thermistor_platform_data *pdata;
const struct ntc_compensation *comp;
struct device *dev;
int n_comp;
char name[PLATFORM_NAME_SIZE];
};
static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
{
if (divisor == 0 && dividend == 0)
return 0;
if (divisor == 0)
return UINT_MAX;
return div64_u64(dividend, divisor);
}
static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uV)
{
struct ntc_thermistor_platform_data *pdata = data->pdata;
u64 mV = uV / 1000;
u64 pmV = pdata->pullup_uV / 1000;
u64 N, puO, pdO;
puO = pdata->pullup_ohm;
pdO = pdata->pulldown_ohm;
if (mV == 0) {
if (pdata->connect == NTC_CONNECTED_POSITIVE)
return INT_MAX;
return 0;
}
if (mV >= pmV)
return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
0 : INT_MAX;
if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
N = div64_u64_safe(pdO * (pmV - mV), mV);
else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
N = div64_u64_safe(puO * mV, pmV - mV);
else if (pdata->connect == NTC_CONNECTED_POSITIVE)
N = div64_u64_safe(pdO * puO * (pmV - mV),
puO * mV - pdO * (pmV - mV));
else
N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);
if (N > INT_MAX)
N = INT_MAX;
return N;
}
static void lookup_comp(struct ntc_data *data, unsigned int ohm,
int *i_low, int *i_high)
{
int start, end, mid;
/*
* Handle special cases: Resistance is higher than or equal to
* resistance in first table entry, or resistance is lower or equal
* to resistance in last table entry.
* In these cases, return i_low == i_high, either pointing to the
* beginning or to the end of the table depending on the condition.
*/
if (ohm >= data->comp[0].ohm) {
*i_low = 0;
*i_high = 0;
return;
}
if (ohm <= data->comp[data->n_comp - 1].ohm) {
*i_low = data->n_comp - 1;
*i_high = data->n_comp - 1;
return;
}
/* Do a binary search on compensation table */
start = 0;
end = data->n_comp;
while (start < end) {
mid = start + (end - start) / 2;
/*
* start <= mid < end
* data->comp[start].ohm > ohm >= data->comp[end].ohm
*
* We could check for "ohm == data->comp[mid].ohm" here, but
* that is a quite unlikely condition, and we would have to
* check again after updating start. Check it at the end instead
* for simplicity.
*/
if (ohm >= data->comp[mid].ohm) {
end = mid;
} else {
start = mid + 1;
/*
* ohm >= data->comp[start].ohm might be true here,
* since we set start to mid + 1. In that case, we are
* done. We could keep going, but the condition is quite
* likely to occur, so it is worth checking for it.
*/
if (ohm >= data->comp[start].ohm)
end = start;
}
/*
* start <= end
* data->comp[start].ohm >= ohm >= data->comp[end].ohm
*/
}
/*
* start == end
* ohm >= data->comp[end].ohm
*/
*i_low = end;
if (ohm == data->comp[end].ohm)
*i_high = end;
else
*i_high = end - 1;
}
static int get_temp_mC(struct ntc_data *data, unsigned int ohm)
{
int low, high;
int temp;
lookup_comp(data, ohm, &low, &high);
if (low == high) {
/* Unable to use linear approximation */
temp = data->comp[low].temp_C * 1000;
} else {
temp = data->comp[low].temp_C * 1000 +
((data->comp[high].temp_C - data->comp[low].temp_C) *
1000 * ((int)ohm - (int)data->comp[low].ohm)) /
((int)data->comp[high].ohm - (int)data->comp[low].ohm);
}
return temp;
}
static int ntc_thermistor_get_ohm(struct ntc_data *data)
{
int read_uV;
if (data->pdata->read_ohm)
return data->pdata->read_ohm();
if (data->pdata->read_uV) {
read_uV = data->pdata->read_uV();
if (read_uV < 0)
return read_uV;
return get_ohm_of_thermistor(data, read_uV);
}
return -EINVAL;
}
static ssize_t ntc_show_name(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ntc_data *data = dev_get_drvdata(dev);
return sprintf(buf, "%s\n", data->name);
}
static ssize_t ntc_show_type(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "4\n");
}
static ssize_t ntc_show_temp(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ntc_data *data = dev_get_drvdata(dev);
int ohm;
ohm = ntc_thermistor_get_ohm(data);
if (ohm < 0)
return ohm;
return sprintf(buf, "%d\n", get_temp_mC(data, ohm));
}
static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
static struct attribute *ntc_attributes[] = {
&dev_attr_name.attr,
&sensor_dev_attr_temp1_type.dev_attr.attr,
&sensor_dev_attr_temp1_input.dev_attr.attr,
NULL,
};
static const struct attribute_group ntc_attr_group = {
.attrs = ntc_attributes,
};
static int ntc_thermistor_probe(struct platform_device *pdev)
{
struct ntc_data *data;
struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
int ret = 0;
if (!pdata) {
dev_err(&pdev->dev, "No platform init data supplied.\n");
return -ENODEV;
}
/* Either one of the two is required. */
if (!pdata->read_uV && !pdata->read_ohm) {
dev_err(&pdev->dev,
"Both read_uV and read_ohm missing. Need either one of the two.\n");
return -EINVAL;
}
if (pdata->read_uV && pdata->read_ohm) {
dev_warn(&pdev->dev,
"Only one of read_uV and read_ohm is needed; ignoring read_uV.\n");
pdata->read_uV = NULL;
}
if (pdata->read_uV && (pdata->pullup_uV == 0 ||
(pdata->pullup_ohm == 0 && pdata->connect ==
NTC_CONNECTED_GROUND) ||
(pdata->pulldown_ohm == 0 && pdata->connect ==
NTC_CONNECTED_POSITIVE) ||
(pdata->connect != NTC_CONNECTED_POSITIVE &&
pdata->connect != NTC_CONNECTED_GROUND))) {
dev_err(&pdev->dev,
"Required data to use read_uV not supplied.\n");
return -EINVAL;
}
data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->dev = &pdev->dev;
data->pdata = pdata;
strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
switch (pdev->id_entry->driver_data) {
case TYPE_NCPXXWB473:
data->comp = ncpXXwb473;
data->n_comp = ARRAY_SIZE(ncpXXwb473);
break;
case TYPE_NCPXXWL333:
data->comp = ncpXXwl333;
data->n_comp = ARRAY_SIZE(ncpXXwl333);
break;
default:
dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
pdev->id_entry->driver_data,
pdev->id_entry->name);
return -EINVAL;
}
platform_set_drvdata(pdev, data);
ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
if (ret) {
dev_err(data->dev, "unable to create sysfs files\n");
return ret;
}
data->hwmon_dev = hwmon_device_register(data->dev);
if (IS_ERR(data->hwmon_dev)) {
dev_err(data->dev, "unable to register as hwmon device.\n");
ret = PTR_ERR(data->hwmon_dev);
goto err_after_sysfs;
}
dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
pdev->name, pdev->id, pdev->id_entry->name,
pdev->id_entry->driver_data);
return 0;
err_after_sysfs:
sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
return ret;
}
static int ntc_thermistor_remove(struct platform_device *pdev)
{
struct ntc_data *data = platform_get_drvdata(pdev);
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
platform_set_drvdata(pdev, NULL);
return 0;
}
static const struct platform_device_id ntc_thermistor_id[] = {
{ "ncp15wb473", TYPE_NCPXXWB473 },
{ "ncp18wb473", TYPE_NCPXXWB473 },
{ "ncp21wb473", TYPE_NCPXXWB473 },
{ "ncp03wb473", TYPE_NCPXXWB473 },
{ "ncp15wl333", TYPE_NCPXXWL333 },
{ },
};
static struct platform_driver ntc_thermistor_driver = {
.driver = {
.name = "ntc-thermistor",
.owner = THIS_MODULE,
},
.probe = ntc_thermistor_probe,
.remove = ntc_thermistor_remove,
.id_table = ntc_thermistor_id,
};
module_platform_driver(ntc_thermistor_driver);
MODULE_DESCRIPTION("NTC Thermistor Driver");
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ntc-thermistor");
