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linux/drivers/hwmon/ntc_thermistor.c
Naveen Krishna Chatradhi 9e8269de10 hwmon: (ntc_thermistor) Add DT with IIO support to NTC thermistor driver 
This patch adds DT support to NTC driver to parse the
platform data.

Also adds the support to work as an iio device client.

During the probe ntc driver gets the respective channels of ADC
and uses iio_raw_read calls to get the ADC converted value.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
[Guenter Roeck: fixed Kconfig dependencies; use ERR_CAST]
Tested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2013-04-07 21:16:38 -07:00

539 lines
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/*
* 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/of.h>
#include <linux/of_device.h>
#include <linux/platform_data/ntc_thermistor.h>
#include <linux/iio/iio.h>
#include <linux/iio/machine.h>
#include <linux/iio/driver.h>
#include <linux/iio/consumer.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
struct ntc_compensation {
int temp_C;
unsigned int ohm;
};
static const struct platform_device_id ntc_thermistor_id[] = {
{ "ncp15wb473", TYPE_NCPXXWB473 },
{ "ncp18wb473", TYPE_NCPXXWB473 },
{ "ncp21wb473", TYPE_NCPXXWB473 },
{ "ncp03wb473", TYPE_NCPXXWB473 },
{ "ncp15wl333", TYPE_NCPXXWL333 },
{ },
};
/*
* 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];
};
#ifdef CONFIG_OF
static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
{
struct iio_channel *channel = pdata->chan;
unsigned int result;
int val, ret;
ret = iio_read_channel_raw(channel, &val);
if (ret < 0) {
pr_err("read channel() error: %d\n", ret);
return ret;
}
/* unit: mV */
result = pdata->pullup_uV * val;
result >>= 12;
return result;
}
static const struct of_device_id ntc_match[] = {
{ .compatible = "ntc,ncp15wb473",
.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
{ .compatible = "ntc,ncp18wb473",
.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
{ .compatible = "ntc,ncp21wb473",
.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
{ .compatible = "ntc,ncp03wb473",
.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
{ .compatible = "ntc,ncp15wl333",
.data = &ntc_thermistor_id[TYPE_NCPXXWL333] },
{ },
};
MODULE_DEVICE_TABLE(of, ntc_match);
static struct ntc_thermistor_platform_data *
ntc_thermistor_parse_dt(struct platform_device *pdev)
{
struct iio_channel *chan;
struct device_node *np = pdev->dev.of_node;
struct ntc_thermistor_platform_data *pdata;
if (!np)
return NULL;
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return ERR_PTR(-ENOMEM);
chan = iio_channel_get(&pdev->dev, NULL);
if (IS_ERR(chan))
return ERR_CAST(chan);
if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uV))
return ERR_PTR(-ENODEV);
if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
return ERR_PTR(-ENODEV);
if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
return ERR_PTR(-ENODEV);
if (of_find_property(np, "connected-positive", NULL))
pdata->connect = NTC_CONNECTED_POSITIVE;
else /* status change should be possible if not always on. */
pdata->connect = NTC_CONNECTED_GROUND;
pdata->chan = chan;
pdata->read_uV = ntc_adc_iio_read;
return pdata;
}
static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
{
if (pdata->chan)
iio_channel_release(pdata->chan);
}
#else
static struct ntc_thermistor_platform_data *
ntc_thermistor_parse_dt(struct platform_device *pdev)
{
return NULL;
}
static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
{ }
#endif
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(data->pdata);
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)
{
const struct of_device_id *of_id =
of_match_device(of_match_ptr(ntc_match), &pdev->dev);
const struct platform_device_id *pdev_id;
struct ntc_thermistor_platform_data *pdata;
struct ntc_data *data;
int ret;
pdata = ntc_thermistor_parse_dt(pdev);
if (IS_ERR(pdata))
return PTR_ERR(pdata);
else if (pdata == NULL)
pdata = pdev->dev.platform_data;
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;
pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
data->dev = &pdev->dev;
data->pdata = pdata;
strlcpy(data->name, pdev_id->name, sizeof(data->name));
switch (pdev_id->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->driver_data, pdev_id->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 type: %s successfully probed.\n",
pdev->name);
return 0;
err_after_sysfs:
sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
ntc_iio_channel_release(pdata);
return ret;
}
static int ntc_thermistor_remove(struct platform_device *pdev)
{
struct ntc_data *data = platform_get_drvdata(pdev);
struct ntc_thermistor_platform_data *pdata = data->pdata;
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
ntc_iio_channel_release(pdata);
platform_set_drvdata(pdev, NULL);
return 0;
}
static struct platform_driver ntc_thermistor_driver = {
.driver = {
.name = "ntc-thermistor",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(ntc_match),
},
.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");
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