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kernel-fxtec-pro1x/drivers/hwmon/tmp102.c
Nishanth Menon 00917b5c55 hwmon: (tmp102) Force wait for conversion time for the first valid data 
TMP102 works based on conversions done periodically. However, as per
the TMP102 data sheet[1] the first conversion is triggered immediately
after we program the configuration register. The temperature data
registers do not reflect proper data until the first conversion is
complete (in our case HZ/4).

The driver currently sets the last_update to be jiffies - HZ, just
after the configuration is complete. When TMP102 driver registers
with the thermal framework, it immediately tries to read the sensor
temperature data. This takes place even before the conversion on the
TMP102 is complete and results in an invalid temperature read.

Depending on the value read, this may cause thermal framework to
assume that a critical temperature event has occurred and attempts to
shutdown the system.

Instead of causing an invalid mid-conversion value to be read
erroneously, we mark the last_update to be in-line with the current
jiffies. This allows the tmp102_update_device function to skip update
until the required conversion time is complete. Further, we ensure to
return -EAGAIN result instead of returning spurious temperature (such
as 0C) values to the caller to prevent any wrong decisions made with
such values. NOTE: this allows the read functions not to be blocking
and allows the callers to make the decision if they would like to
block or try again later. At least the current user(thermal) seems to
handle this by retrying later.

A simpler alternative approach could be to sleep in the probe for the
duration required, but that will result in latency that is undesirable
and delay boot sequence un-necessarily.

[1] http://www.ti.com/lit/ds/symlink/tmp102.pdf

Cc: Eduardo Valentin <edubezval@gmail.com>
Reported-by: Aparna Balasubramanian <aparnab@ti.com>
Reported-by: Elvita Lobo <elvita@ti.com>
Reported-by: Yan Liu <yan-liu@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2015-12-10 08:14:22 -08:00

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/* Texas Instruments TMP102 SMBus temperature sensor driver
*
* Copyright (C) 2010 Steven King <sfking@fdwdc.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., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/jiffies.h>
#include <linux/thermal.h>
#include <linux/of.h>
#define DRIVER_NAME "tmp102"
#define TMP102_TEMP_REG 0x00
#define TMP102_CONF_REG 0x01
/* note: these bit definitions are byte swapped */
#define TMP102_CONF_SD 0x0100
#define TMP102_CONF_TM 0x0200
#define TMP102_CONF_POL 0x0400
#define TMP102_CONF_F0 0x0800
#define TMP102_CONF_F1 0x1000
#define TMP102_CONF_R0 0x2000
#define TMP102_CONF_R1 0x4000
#define TMP102_CONF_OS 0x8000
#define TMP102_CONF_EM 0x0010
#define TMP102_CONF_AL 0x0020
#define TMP102_CONF_CR0 0x0040
#define TMP102_CONF_CR1 0x0080
#define TMP102_TLOW_REG 0x02
#define TMP102_THIGH_REG 0x03
struct tmp102 {
struct i2c_client *client;
struct device *hwmon_dev;
struct thermal_zone_device *tz;
struct mutex lock;
u16 config_orig;
unsigned long last_update;
int temp[3];
bool first_time;
};
/* convert left adjusted 13-bit TMP102 register value to milliCelsius */
static inline int tmp102_reg_to_mC(s16 val)
{
return ((val & ~0x01) * 1000) / 128;
}
/* convert milliCelsius to left adjusted 13-bit TMP102 register value */
static inline u16 tmp102_mC_to_reg(int val)
{
return (val * 128) / 1000;
}
static const u8 tmp102_reg[] = {
TMP102_TEMP_REG,
TMP102_TLOW_REG,
TMP102_THIGH_REG,
};
static struct tmp102 *tmp102_update_device(struct device *dev)
{
struct tmp102 *tmp102 = dev_get_drvdata(dev);
struct i2c_client *client = tmp102->client;
mutex_lock(&tmp102->lock);
if (time_after(jiffies, tmp102->last_update + HZ / 3)) {
int i;
for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) {
int status = i2c_smbus_read_word_swapped(client,
tmp102_reg[i]);
if (status > -1)
tmp102->temp[i] = tmp102_reg_to_mC(status);
}
tmp102->last_update = jiffies;
tmp102->first_time = false;
}
mutex_unlock(&tmp102->lock);
return tmp102;
}
static int tmp102_read_temp(void *dev, int *temp)
{
struct tmp102 *tmp102 = tmp102_update_device(dev);
/* Is it too early even to return a conversion? */
if (tmp102->first_time) {
dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
return -EAGAIN;
}
*temp = tmp102->temp[0];
return 0;
}
static ssize_t tmp102_show_temp(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
struct tmp102 *tmp102 = tmp102_update_device(dev);
/* Is it too early even to return a read? */
if (tmp102->first_time)
return -EAGAIN;
return sprintf(buf, "%d\n", tmp102->temp[sda->index]);
}
static ssize_t tmp102_set_temp(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
struct tmp102 *tmp102 = dev_get_drvdata(dev);
struct i2c_client *client = tmp102->client;
long val;
int status;
if (kstrtol(buf, 10, &val) < 0)
return -EINVAL;
val = clamp_val(val, -256000, 255000);
mutex_lock(&tmp102->lock);
tmp102->temp[sda->index] = val;
status = i2c_smbus_write_word_swapped(client, tmp102_reg[sda->index],
tmp102_mC_to_reg(val));
mutex_unlock(&tmp102->lock);
return status ? : count;
}
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, tmp102_show_temp, NULL , 0);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO, tmp102_show_temp,
tmp102_set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, tmp102_show_temp,
tmp102_set_temp, 2);
static struct attribute *tmp102_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
&sensor_dev_attr_temp1_max.dev_attr.attr,
NULL
};
ATTRIBUTE_GROUPS(tmp102);
#define TMP102_CONFIG (TMP102_CONF_TM | TMP102_CONF_EM | TMP102_CONF_CR1)
#define TMP102_CONFIG_RD_ONLY (TMP102_CONF_R0 | TMP102_CONF_R1 | TMP102_CONF_AL)
static const struct thermal_zone_of_device_ops tmp102_of_thermal_ops = {
.get_temp = tmp102_read_temp,
};
static int tmp102_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct tmp102 *tmp102;
int status;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WORD_DATA)) {
dev_err(dev,
"adapter doesn't support SMBus word transactions\n");
return -ENODEV;
}
tmp102 = devm_kzalloc(dev, sizeof(*tmp102), GFP_KERNEL);
if (!tmp102)
return -ENOMEM;
i2c_set_clientdata(client, tmp102);
tmp102->client = client;
status = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (status < 0) {
dev_err(dev, "error reading config register\n");
return status;
}
tmp102->config_orig = status;
status = i2c_smbus_write_word_swapped(client, TMP102_CONF_REG,
TMP102_CONFIG);
if (status < 0) {
dev_err(dev, "error writing config register\n");
goto fail_restore_config;
}
status = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (status < 0) {
dev_err(dev, "error reading config register\n");
goto fail_restore_config;
}
status &= ~TMP102_CONFIG_RD_ONLY;
if (status != TMP102_CONFIG) {
dev_err(dev, "config settings did not stick\n");
status = -ENODEV;
goto fail_restore_config;
}
tmp102->last_update = jiffies;
/* Mark that we are not ready with data until conversion is complete */
tmp102->first_time = true;
mutex_init(&tmp102->lock);
hwmon_dev = hwmon_device_register_with_groups(dev, client->name,
tmp102, tmp102_groups);
if (IS_ERR(hwmon_dev)) {
dev_dbg(dev, "unable to register hwmon device\n");
status = PTR_ERR(hwmon_dev);
goto fail_restore_config;
}
tmp102->hwmon_dev = hwmon_dev;
tmp102->tz = thermal_zone_of_sensor_register(hwmon_dev, 0, hwmon_dev,
&tmp102_of_thermal_ops);
if (IS_ERR(tmp102->tz))
tmp102->tz = NULL;
dev_info(dev, "initialized\n");
return 0;
fail_restore_config:
i2c_smbus_write_word_swapped(client, TMP102_CONF_REG,
tmp102->config_orig);
return status;
}
static int tmp102_remove(struct i2c_client *client)
{
struct tmp102 *tmp102 = i2c_get_clientdata(client);
thermal_zone_of_sensor_unregister(tmp102->hwmon_dev, tmp102->tz);
hwmon_device_unregister(tmp102->hwmon_dev);
/* Stop monitoring if device was stopped originally */
if (tmp102->config_orig & TMP102_CONF_SD) {
int config;
config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (config >= 0)
i2c_smbus_write_word_swapped(client, TMP102_CONF_REG,
config | TMP102_CONF_SD);
}
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int tmp102_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
int config;
config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (config < 0)
return config;
config |= TMP102_CONF_SD;
return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
}
static int tmp102_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
int config;
config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (config < 0)
return config;
config &= ~TMP102_CONF_SD;
return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
}
#endif /* CONFIG_PM */
static SIMPLE_DEV_PM_OPS(tmp102_dev_pm_ops, tmp102_suspend, tmp102_resume);
static const struct i2c_device_id tmp102_id[] = {
{ "tmp102", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, tmp102_id);
static struct i2c_driver tmp102_driver = {
.driver.name = DRIVER_NAME,
.driver.pm = &tmp102_dev_pm_ops,
.probe = tmp102_probe,
.remove = tmp102_remove,
.id_table = tmp102_id,
};
module_i2c_driver(tmp102_driver);
MODULE_AUTHOR("Steven King <sfking@fdwdc.com>");
MODULE_DESCRIPTION("Texas Instruments TMP102 temperature sensor driver");
MODULE_LICENSE("GPL");
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